The reproductive biology and artificial breeding of ningu Labeo victorianus (Pisces: Cyprinidae)
- Authors: Rutaisire, Justus
- Date: 2004
- Subjects: Fishes -- Victoria, Lake , Cyprinidae -- Reproduction , Labeo -- Reproduction , Labeo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5317 , http://hdl.handle.net/10962/d1005162
- Description: Lake Victoria, the largest tropical lake, has faced an unprecedented assault on its ecosystem through a variety of anthropomorphic causes that include the introduction of Nile perch Lates niloticus and over-fishing. As a result there have been species extinctions and declining fish population trends. This thesis explores options for reversing these declining population trends and the restoration of collapsed fisheries based on indigenous non-cichlid species. A candidate species was chosen - the cyprinid fish Labeo victorianus. This thesis studied various aspects of L. victorianus' reproductive biology in two geographically distant populations. These included general reproductive patterns in relation to proximate environmental conditions, gonadal development and recrudescence, sex development, characterisation of genetic and morphological diversity, and induced spawning. Fish from both populations were found to be potamodrometic, and highly fecund, iteroparous spawners. L. victorianus was also shown to be an undifferentiated gonochorist, where all individuals pass through an intersexual juvenile stage prior to differentiation, and maturation to either sex. Sexual maturity was attained at a significantly larger size within the Kagera River than that of Sio River fish – possibly as a response to genotypic and/or phenotypic differences. Spawning seemed to be synchronised with rainfall in Kagera River - a pattern that was not strictly adhered to with the Sio River. Thorough microscopic investigation of recrudescence patterns indicated there was uninterrupted spawning in fish from the Kagera River followed by Type I oocyte atresia. In contrast, there was a 90% spawning failure, as characterised by Type II oocyte atresia, within the Sio River population. Aspects of spermatogenesis and sperm ultrastructure using light- and ultramicrotomic methods are described. Although the populations had varying reproductive biology parameters and were morphologically distinct, they remained undifferentiated at the mitochondrial level. Both populations were characterised by low nucleotide diversity – a feature attributed to a bottleneck event. The option of captive breeding was explored by conducting induced spawning experiments. Success was only achieved with a decapeptide Gonadotropic Releasing Hormone ([D-Arg⁶, Pro⁹-NEt])-sGnRH) in combination with a water-soluble dopamine receptor antagonist metoclopramide. This thesis stresses the importance of a research-oriented approach in the conservation of Lake Victoria's indigenous fish resources. It was concluded that information needed for the development of management policies can be generated within a reasonably short time period, of approximately three years, with modest levels of funding support.
- Full Text:
- Date Issued: 2004
- Authors: Rutaisire, Justus
- Date: 2004
- Subjects: Fishes -- Victoria, Lake , Cyprinidae -- Reproduction , Labeo -- Reproduction , Labeo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5317 , http://hdl.handle.net/10962/d1005162
- Description: Lake Victoria, the largest tropical lake, has faced an unprecedented assault on its ecosystem through a variety of anthropomorphic causes that include the introduction of Nile perch Lates niloticus and over-fishing. As a result there have been species extinctions and declining fish population trends. This thesis explores options for reversing these declining population trends and the restoration of collapsed fisheries based on indigenous non-cichlid species. A candidate species was chosen - the cyprinid fish Labeo victorianus. This thesis studied various aspects of L. victorianus' reproductive biology in two geographically distant populations. These included general reproductive patterns in relation to proximate environmental conditions, gonadal development and recrudescence, sex development, characterisation of genetic and morphological diversity, and induced spawning. Fish from both populations were found to be potamodrometic, and highly fecund, iteroparous spawners. L. victorianus was also shown to be an undifferentiated gonochorist, where all individuals pass through an intersexual juvenile stage prior to differentiation, and maturation to either sex. Sexual maturity was attained at a significantly larger size within the Kagera River than that of Sio River fish – possibly as a response to genotypic and/or phenotypic differences. Spawning seemed to be synchronised with rainfall in Kagera River - a pattern that was not strictly adhered to with the Sio River. Thorough microscopic investigation of recrudescence patterns indicated there was uninterrupted spawning in fish from the Kagera River followed by Type I oocyte atresia. In contrast, there was a 90% spawning failure, as characterised by Type II oocyte atresia, within the Sio River population. Aspects of spermatogenesis and sperm ultrastructure using light- and ultramicrotomic methods are described. Although the populations had varying reproductive biology parameters and were morphologically distinct, they remained undifferentiated at the mitochondrial level. Both populations were characterised by low nucleotide diversity – a feature attributed to a bottleneck event. The option of captive breeding was explored by conducting induced spawning experiments. Success was only achieved with a decapeptide Gonadotropic Releasing Hormone ([D-Arg⁶, Pro⁹-NEt])-sGnRH) in combination with a water-soluble dopamine receptor antagonist metoclopramide. This thesis stresses the importance of a research-oriented approach in the conservation of Lake Victoria's indigenous fish resources. It was concluded that information needed for the development of management policies can be generated within a reasonably short time period, of approximately three years, with modest levels of funding support.
- Full Text:
- Date Issued: 2004
The mentally retarded offender in a forensic setting: a South African study
- Authors: Solomons, Warren Stanley
- Date: 2004
- Subjects: Mentally ill offenders -- South Africa , Forensic psychology , People with mental disabilities and crime -- South Africa , People with mental disabilities -- Rehabilitation , Mental health laws -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3063 , http://hdl.handle.net/10962/d1002572 , Mentally ill offenders -- South Africa , Forensic psychology , People with mental disabilities and crime -- South Africa , People with mental disabilities -- Rehabilitation , Mental health laws -- South Africa
- Description: This study examined, within the South African context, the prevalence of mental retardation in a forensic observation setting, and the impediments of and successes to forensic rehabilitation. The results of the study indicated that a significant amount of forensic observation patients (25.16%) are ultimately diagnosed as being mentally retarded, with 39.24 percent of such offenders being found unfit to plead. Further 32.91 percent of the same sample was found to be not responsible for their actions. A link was also drawn between the mentally retarded offender and violent offenses. The advantages and disadvantages of a current rehabilitative process are discussed in light of alternate community-based forms of rehabilitation that are being implemented in other countries, for example the United States of America, with a view towards investigated their usefulness and adaptability to South African circumstances. The findings of the study have implications for mental health professionals working within forensic settings concerning the future management of mentally retarded offenders, particularly within the rehabilitative process .
- Full Text:
- Date Issued: 2004
- Authors: Solomons, Warren Stanley
- Date: 2004
- Subjects: Mentally ill offenders -- South Africa , Forensic psychology , People with mental disabilities and crime -- South Africa , People with mental disabilities -- Rehabilitation , Mental health laws -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3063 , http://hdl.handle.net/10962/d1002572 , Mentally ill offenders -- South Africa , Forensic psychology , People with mental disabilities and crime -- South Africa , People with mental disabilities -- Rehabilitation , Mental health laws -- South Africa
- Description: This study examined, within the South African context, the prevalence of mental retardation in a forensic observation setting, and the impediments of and successes to forensic rehabilitation. The results of the study indicated that a significant amount of forensic observation patients (25.16%) are ultimately diagnosed as being mentally retarded, with 39.24 percent of such offenders being found unfit to plead. Further 32.91 percent of the same sample was found to be not responsible for their actions. A link was also drawn between the mentally retarded offender and violent offenses. The advantages and disadvantages of a current rehabilitative process are discussed in light of alternate community-based forms of rehabilitation that are being implemented in other countries, for example the United States of America, with a view towards investigated their usefulness and adaptability to South African circumstances. The findings of the study have implications for mental health professionals working within forensic settings concerning the future management of mentally retarded offenders, particularly within the rehabilitative process .
- Full Text:
- Date Issued: 2004
Investigation of the larval parasitoids of the false codling moth, Cryptophlebia Leucotreta (Meyrick) (Lepidoptera: Tortricidae), on citrus in South Africa
- Authors: Sishuba, Nomahlubi
- Date: 2004
- Subjects: Cryptophlebia leucotreta , Tortricidae , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Parasitoids , Citrus -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5918 , http://hdl.handle.net/10962/d1016267
- Description: The study examined the larval parasitoids of Cryptophlebia leucotreta (Meyrick) on citrus in South Africa and aimed to improve the existing rearing techniques of C. leucotreta with a view to mass rearing of biological control agents. The biological characteristics of Agathis bishopi Nixon (Hymenoptera: Braconidae) were studied, with an emphasis on parasitism rates in the field, host stage preference, developmental rate, life span and offspring sex ratios. Two larval parasitoids, A. bishopi and Apophua leucotretae (Wilkinson) (Hymenoptera: Ichneumonidae), and an egg parasitoid, Trichogrammatoidea cryptophlebiae Nagaraja (Hymenoptera: Trichogrammatidae), were recorded on C. leucotreta on citrus. A. bishopi was the more abundant of the larval parasitoids and exhibited density dependent parasitism. The highest parasitism rates were observed in December with up to 38% in Sundays River Valley and 34% in Gamtoos River Valley, at a time when the highest false codling moth infestations were observed. Agathis bishopi was recorded only in the Eastern Cape Province. The sex ratio of A. bishopi was biased towards females throughout the study (77% in Gamtoos River Valley and 72% in Sundays River Valley). Agathis bishopi is a solitary, koinobiont, larval-pupal endoparasitoid. The species showed a preference for 1st and 2"d instar hosts. Females regulate the sex of their progeny according to the size and larval stage of the host, ovipositing unfertilised eggs in younger, smaller larvae (1st instars) and fertilised eggs in older, larger larvae (2nd instars). The developmental rate of A. bishopi is in synchrony with that of the moth and adults emerge when adult moths that have escaped parasitism emerge. Agathis bishopi and T. cryptophlebiae compliment each other because they have different niches and strategies of attack. Integrating A. bishopi and T. cryptophlebiae into the management of citrus orchards has potential to suppress false codling moth. Larger rearing containers seemed ideal for large-scale rearing of false codling moth. A higher percentage of adults was obtained from larvae reared in larger containers than in smaller ones. The width of the sponges used as stoppers prevented escape of the larvae. Media prepared in larger containers are easier and simpler to prepare than in smaller ones, thus eliminating many precautions otherwise necessary to prevent contamination. Moth production was greatly reduced by the high concentration of Sporekill used for egg decontamination.
- Full Text:
- Date Issued: 2004
- Authors: Sishuba, Nomahlubi
- Date: 2004
- Subjects: Cryptophlebia leucotreta , Tortricidae , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Parasitoids , Citrus -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5918 , http://hdl.handle.net/10962/d1016267
- Description: The study examined the larval parasitoids of Cryptophlebia leucotreta (Meyrick) on citrus in South Africa and aimed to improve the existing rearing techniques of C. leucotreta with a view to mass rearing of biological control agents. The biological characteristics of Agathis bishopi Nixon (Hymenoptera: Braconidae) were studied, with an emphasis on parasitism rates in the field, host stage preference, developmental rate, life span and offspring sex ratios. Two larval parasitoids, A. bishopi and Apophua leucotretae (Wilkinson) (Hymenoptera: Ichneumonidae), and an egg parasitoid, Trichogrammatoidea cryptophlebiae Nagaraja (Hymenoptera: Trichogrammatidae), were recorded on C. leucotreta on citrus. A. bishopi was the more abundant of the larval parasitoids and exhibited density dependent parasitism. The highest parasitism rates were observed in December with up to 38% in Sundays River Valley and 34% in Gamtoos River Valley, at a time when the highest false codling moth infestations were observed. Agathis bishopi was recorded only in the Eastern Cape Province. The sex ratio of A. bishopi was biased towards females throughout the study (77% in Gamtoos River Valley and 72% in Sundays River Valley). Agathis bishopi is a solitary, koinobiont, larval-pupal endoparasitoid. The species showed a preference for 1st and 2"d instar hosts. Females regulate the sex of their progeny according to the size and larval stage of the host, ovipositing unfertilised eggs in younger, smaller larvae (1st instars) and fertilised eggs in older, larger larvae (2nd instars). The developmental rate of A. bishopi is in synchrony with that of the moth and adults emerge when adult moths that have escaped parasitism emerge. Agathis bishopi and T. cryptophlebiae compliment each other because they have different niches and strategies of attack. Integrating A. bishopi and T. cryptophlebiae into the management of citrus orchards has potential to suppress false codling moth. Larger rearing containers seemed ideal for large-scale rearing of false codling moth. A higher percentage of adults was obtained from larvae reared in larger containers than in smaller ones. The width of the sponges used as stoppers prevented escape of the larvae. Media prepared in larger containers are easier and simpler to prepare than in smaller ones, thus eliminating many precautions otherwise necessary to prevent contamination. Moth production was greatly reduced by the high concentration of Sporekill used for egg decontamination.
- Full Text:
- Date Issued: 2004
Journeys of the learning soul: Plato to Descartes
- Authors: Hugo, Wayne
- Date: 2004
- Subjects: Education -- Philosophy Education -- History Education, Ancient Education, Greek
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1884 , http://hdl.handle.net/10962/d1005917
- Description: This thesis aims to build up a picture of what it has meant for us within the western canon to educate a human being through the depths and heights of existence. It uses narrative accounts of educational journeys from ancient, medieval and early modern sources to develop an integral picture of the spectrum of education along with the techniques and fore-structures needed to guide a student through the various stages and encounters. Key metaphors, journeys and relationships - Diotirna's ladder of beauty, Plato's cave, Philo's Abraham and Sarah, Origen's bride and Bridegroom, Plotinus' journey of the alone to the Alone, Augustine's Confessions, the tragic love of Abelard and Heloise, Dante's encounters in the infernal, purgatorial and paradisical realms of human experience, Shakespeare's great playing within the same realm, and Descartes' doubting genius provide a rich ensemble, each resonating with the next, opening out intellectual, affective, volitional, and imaginative paths through the full terrain of human existence. This multidimensional approach points towards a flexible and insightful pedagogics that works with the enormous variety and capacity of human learning rather than heavy-handedly insisting on one path, or, even worse, not recognizing and dealing with specific areas of human living that occur in the upper and lower reaches of our educational endeavours. Phenomenological, Hermeneutic and Integral methods suggested by Heidegger and Wilber amongst others were used to inform the process of research. The results of this thesis are not contained in its reconunendations but in the effects of its reading. It is itself a tool that embodies and encourages the principles of an educational tradition that has existed within the history of western learning, not seeking a return to ancient or medieval ways but to provide a backlight that assists current initiatives working with the full range of human potential.
- Full Text:
- Date Issued: 2004
- Authors: Hugo, Wayne
- Date: 2004
- Subjects: Education -- Philosophy Education -- History Education, Ancient Education, Greek
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1884 , http://hdl.handle.net/10962/d1005917
- Description: This thesis aims to build up a picture of what it has meant for us within the western canon to educate a human being through the depths and heights of existence. It uses narrative accounts of educational journeys from ancient, medieval and early modern sources to develop an integral picture of the spectrum of education along with the techniques and fore-structures needed to guide a student through the various stages and encounters. Key metaphors, journeys and relationships - Diotirna's ladder of beauty, Plato's cave, Philo's Abraham and Sarah, Origen's bride and Bridegroom, Plotinus' journey of the alone to the Alone, Augustine's Confessions, the tragic love of Abelard and Heloise, Dante's encounters in the infernal, purgatorial and paradisical realms of human experience, Shakespeare's great playing within the same realm, and Descartes' doubting genius provide a rich ensemble, each resonating with the next, opening out intellectual, affective, volitional, and imaginative paths through the full terrain of human existence. This multidimensional approach points towards a flexible and insightful pedagogics that works with the enormous variety and capacity of human learning rather than heavy-handedly insisting on one path, or, even worse, not recognizing and dealing with specific areas of human living that occur in the upper and lower reaches of our educational endeavours. Phenomenological, Hermeneutic and Integral methods suggested by Heidegger and Wilber amongst others were used to inform the process of research. The results of this thesis are not contained in its reconunendations but in the effects of its reading. It is itself a tool that embodies and encourages the principles of an educational tradition that has existed within the history of western learning, not seeking a return to ancient or medieval ways but to provide a backlight that assists current initiatives working with the full range of human potential.
- Full Text:
- Date Issued: 2004
A study of Ted Hughes's Birthday letters
- Authors: Highman, Kathryn Barbara
- Date: 2004
- Subjects: Hughes, Ted, 1930-1998 Criticism and interpretation Hughes, Ted, 1930-1998 Birthday Letters
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2193 , http://hdl.handle.net/10962/d1002235
- Description: This thesis focusses on the literary self-reflexivity of Birthday Letters, Ted Hughes's collection of poems addressed to his long-dead first wife, poet Sylvia Plath. By close attention to the language of select poems and a discussion of cross-referencing images and allusions across the volume, and intertextually, I argue that the collection is more self-consciously ordered and designed than the mainly biographical criticism the work has met with suggests. The thesis focusses on the poets' art rather than the biographical context of Birthday Letters, though it does not draw a neat distinction between their lives and their poetry - rather it demonstrates how Birthday Letters itself treats the relationship of art to life thematically. The introduction outlines the context of the volume's genesis and publication and the notions of poetry, myth and drama out of which Hughes works, and introduces the central metaphor of metamorphosis as figured in Ariel's song "Full Fathom Five" from The Tempest, as well as the importance of that play to Plath. Each of the chapters that follow focusses on a cluster of inter-related imagery through a discussion of four or five key poems. Chapter One examines Hughes's portrayal of himself as imprisoned by Plath's poetic portraits, and relates this to the recurring motifs of the snapshot and the Medusa myth. The poems discussed emphasize Hughes's consciousness of the metamorphic and "magical" relationship of art to life. The second chapter discusses Hughes's use of the myth of the labyrinth and the Minotaur, tracing it back to Plath's writings and reading, and pointing out its self-reflexivity: the labyrinth figures Hughes's own loss as well as the labyrinthine nature of writing. The third chapter considers the themes of possession and loss, and how they attach themselves to images of houses and jewels. Possession and loss tum, self-reflexively, upon issues of inheritance and remembrance, notably Hughes's inheritance of Plath's poetic legacy, and his remembrance of her and her poetry through his own poetry. The conclusion pursues connections between the observations made in the separate chapters, outlining the larger context out of which the poems emerge, and returning to the trope of metamorphosis as figured in "Full Fathom Five"
- Full Text:
- Date Issued: 2004
- Authors: Highman, Kathryn Barbara
- Date: 2004
- Subjects: Hughes, Ted, 1930-1998 Criticism and interpretation Hughes, Ted, 1930-1998 Birthday Letters
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2193 , http://hdl.handle.net/10962/d1002235
- Description: This thesis focusses on the literary self-reflexivity of Birthday Letters, Ted Hughes's collection of poems addressed to his long-dead first wife, poet Sylvia Plath. By close attention to the language of select poems and a discussion of cross-referencing images and allusions across the volume, and intertextually, I argue that the collection is more self-consciously ordered and designed than the mainly biographical criticism the work has met with suggests. The thesis focusses on the poets' art rather than the biographical context of Birthday Letters, though it does not draw a neat distinction between their lives and their poetry - rather it demonstrates how Birthday Letters itself treats the relationship of art to life thematically. The introduction outlines the context of the volume's genesis and publication and the notions of poetry, myth and drama out of which Hughes works, and introduces the central metaphor of metamorphosis as figured in Ariel's song "Full Fathom Five" from The Tempest, as well as the importance of that play to Plath. Each of the chapters that follow focusses on a cluster of inter-related imagery through a discussion of four or five key poems. Chapter One examines Hughes's portrayal of himself as imprisoned by Plath's poetic portraits, and relates this to the recurring motifs of the snapshot and the Medusa myth. The poems discussed emphasize Hughes's consciousness of the metamorphic and "magical" relationship of art to life. The second chapter discusses Hughes's use of the myth of the labyrinth and the Minotaur, tracing it back to Plath's writings and reading, and pointing out its self-reflexivity: the labyrinth figures Hughes's own loss as well as the labyrinthine nature of writing. The third chapter considers the themes of possession and loss, and how they attach themselves to images of houses and jewels. Possession and loss tum, self-reflexively, upon issues of inheritance and remembrance, notably Hughes's inheritance of Plath's poetic legacy, and his remembrance of her and her poetry through his own poetry. The conclusion pursues connections between the observations made in the separate chapters, outlining the larger context out of which the poems emerge, and returning to the trope of metamorphosis as figured in "Full Fathom Five"
- Full Text:
- Date Issued: 2004
Laboratory investigation of a simulated industrial task pre- and post-ergonomics intervention
- Authors: Renz, Miriam Christina
- Date: 2004
- Subjects: Human engineering , Musculoskeletal system -- Diseases , Occupational diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5162 , http://hdl.handle.net/10962/d1015806
- Description: The focus of the present study was on the investigation of the effects of an intervention strategy on an industrial task in situ and a simulation of the same task within a laboratory setting. The task of offloading crates from a truck at a local business was simulated in a laboratory setting for rigorous analysis. The effect of an ergonomically sound intervention on selected physical, physiological and perceptual variables was evaluated in a test - retest experimental set-up using 28 young, healthy male students. Each of the two experimental conditions lasted for 16 minutes. In the pre-intervention task subjects were required to transfer the crates from one point to another by sliding them along the floor. During the execution of the post-intervention task responses to reductions in the stacking height and modifications of the working method were evaluated. Results obtained for spinal kinematics during the simulated industrial task indicated a high biomechanical risk, due to large ranges of motion, high velocities and accelerations in the sagittal and transverse planes. The heavy workload of the task was also evident in elevated physiological responses (HR, RF, VT, VE, VO2, RQ, EE) and perceptual ratings (RPE, Body Discomfort). Assessment of the intervention strategy revealed that the high risk industrial task was reduced to moderate acceptable, with measurements of spinal kinematics, physiological and perceptual variables being significantly reduced. An in situ re-assessment of the workers responses to the intervention also elicited reductions in heart rates and perceptual ratings compared to the original task.
- Full Text:
- Date Issued: 2004
- Authors: Renz, Miriam Christina
- Date: 2004
- Subjects: Human engineering , Musculoskeletal system -- Diseases , Occupational diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5162 , http://hdl.handle.net/10962/d1015806
- Description: The focus of the present study was on the investigation of the effects of an intervention strategy on an industrial task in situ and a simulation of the same task within a laboratory setting. The task of offloading crates from a truck at a local business was simulated in a laboratory setting for rigorous analysis. The effect of an ergonomically sound intervention on selected physical, physiological and perceptual variables was evaluated in a test - retest experimental set-up using 28 young, healthy male students. Each of the two experimental conditions lasted for 16 minutes. In the pre-intervention task subjects were required to transfer the crates from one point to another by sliding them along the floor. During the execution of the post-intervention task responses to reductions in the stacking height and modifications of the working method were evaluated. Results obtained for spinal kinematics during the simulated industrial task indicated a high biomechanical risk, due to large ranges of motion, high velocities and accelerations in the sagittal and transverse planes. The heavy workload of the task was also evident in elevated physiological responses (HR, RF, VT, VE, VO2, RQ, EE) and perceptual ratings (RPE, Body Discomfort). Assessment of the intervention strategy revealed that the high risk industrial task was reduced to moderate acceptable, with measurements of spinal kinematics, physiological and perceptual variables being significantly reduced. An in situ re-assessment of the workers responses to the intervention also elicited reductions in heart rates and perceptual ratings compared to the original task.
- Full Text:
- Date Issued: 2004
Cleaning of fouled membranes using enzymes from a sulphidogenic bioreactor
- Authors: Melamane, Xolisa
- Date: 2004
- Subjects: Membrane filters , Membrane filters -- Fouling , Enzymes -- Biotechnology , Enzymes -- Purification , Water -- Purification -- Membrane filtration , Ultrafiltration
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4133 , http://hdl.handle.net/10962/d1015764
- Description: Maintenance of membrane performance requires inevitable cleaning or defouling of fouled membranes. Membrane cleaning using enzymes such as proteases, lipases, α-glucosidases from a sulphidogenic bioreactor was investigated. At first, dilute and concentrated enzyme extract were prepared form the sulphidogenic pellet. Enzyme assays on 0.5 % azocaisen, 1 % triacetin and 1 mg/ml ρ-nitrophenyl-α-D-glucopyranoside were performed using the concentrated enzyme extract (0 – 200 mg/ml). For membrane fouling, an abattoir effluent was obtained from Ostritech Pty (Ltd), Grahamstown, South Africa. The effluent was characterised for presence of potential foulants such as lipids, proteins, amino acids and carbohydrates. Static fouling of polysulphone membranes (0.22 μm, 47 mm) was then performed using the abattoir effluent. Cleaning of the fouled membranes was also performed using at first the dilute and then the concentrated form (200 mg/ml) of enzyme extracts. Qualitative and quantitative biochemical analysis for proteins, lipids and carbohydrates was performed to ascertain the presence of foulants on polysulphone membranes and their removal by dilute or concentrated enzyme extracts. The ability of dilute enzyme extracts to remove proteins lipids, and carbohydrates fouling capillary UF membrane module; their ability to restore permeate fluxes and transmembrane pressure after cleaning/defouling was also investigated. Permeate volumes from this UF membrane module were analysed for protein, amino acids, lipids, and carbohydrates concentrations after fouling and defouling. Fouling was further characterized by standard blocking, cake filtration and pore blocking models using stirred UF cell and polyethersulphone membranes with MWCO of 30 000, 100 000 and 300 000. After characterization of fouling, polyethersulphone membranes with MWCO of 30 000 and 300 000 were defouled using the concentrated enzyme extract (100 mg ml). Enzyme activities at 200 mg/ml of enzyme concentration were 8.071 IU, 86.71 IU and 789.02 IU for proteases, lipases and α-glucosidases. The abattoir effluent contained 553 μg/ml of lipid, 301 μg/ml of protein, 141 μg/ml of total carbohydrate, and 0.63 μg/ml of total reducing sugars. Proteins, lipids and carbohydrates fouling polysulphone membranes after a day were removed by 23.4 %, when a dilute enzyme was used. A concentrated enzyme extract of 200 mg/ml was able to remove proteins, lipids and carbohydrates up to 5 days of fouling by 100 %, 82 %, 71 %, 68 % and 76 % respectively. Defouling of dynamically fouled capillary ultrafiltration membranes using sulphidogenic proteases was successful at pH 10, 37°C, within 1 hour. Sulphidogenic proteases activity was 2.1 U/ml and flux Recovery (FR %) was 64. Characterization of fouling revealed that proteins and lipids were major foulants while low concentration of carbohydrates fouled polyethersulphone membranes. Fouling followed standard blocking for 10 minutes in all the membranes; afterwards fouling adopted cake filtration model for membranes with 30 000 MWCO and pore blocking model for membranes with 300 000 MWCO. A concentration of 100 mg/ml of enzyme extract was able to remove fouling from membranes with MWCO of 30 000. Defouling membranes that followed pore blocking model i.e. 300 000 MWCO was not successful due to a mass transfer problem. From the results of defouling of 30 000 and 300 000 MWCO it was concluded that defouling of cake layer fouling (30 000 MWCO) was successful while defouling of pore blocking fouling was unsuccessful due to a mass transfer problem. The ratio of enzymes present in the enzyme extract when calculated based on enzymatic activity for proteases, lipases and α-glucosidases was 1.1 %, 11 % and 87.9 %. It was hypothesized that apart from proteases, lipases, α and β-glucosidases; phosphatases, sulphatases, amonipeptidases etc. from a sulphidogenic bioreactor clean or defoul cake layer fouling by organic foulants and pore blocking fouling provided the mass transfer problem is solved. However, concentration of enzymes from a sulphidogenic bioreactor has not been optimized yet. Other methods of concentrating the enzyme extract can be investigated for example use of organic solvents.
- Full Text:
- Date Issued: 2004
- Authors: Melamane, Xolisa
- Date: 2004
- Subjects: Membrane filters , Membrane filters -- Fouling , Enzymes -- Biotechnology , Enzymes -- Purification , Water -- Purification -- Membrane filtration , Ultrafiltration
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4133 , http://hdl.handle.net/10962/d1015764
- Description: Maintenance of membrane performance requires inevitable cleaning or defouling of fouled membranes. Membrane cleaning using enzymes such as proteases, lipases, α-glucosidases from a sulphidogenic bioreactor was investigated. At first, dilute and concentrated enzyme extract were prepared form the sulphidogenic pellet. Enzyme assays on 0.5 % azocaisen, 1 % triacetin and 1 mg/ml ρ-nitrophenyl-α-D-glucopyranoside were performed using the concentrated enzyme extract (0 – 200 mg/ml). For membrane fouling, an abattoir effluent was obtained from Ostritech Pty (Ltd), Grahamstown, South Africa. The effluent was characterised for presence of potential foulants such as lipids, proteins, amino acids and carbohydrates. Static fouling of polysulphone membranes (0.22 μm, 47 mm) was then performed using the abattoir effluent. Cleaning of the fouled membranes was also performed using at first the dilute and then the concentrated form (200 mg/ml) of enzyme extracts. Qualitative and quantitative biochemical analysis for proteins, lipids and carbohydrates was performed to ascertain the presence of foulants on polysulphone membranes and their removal by dilute or concentrated enzyme extracts. The ability of dilute enzyme extracts to remove proteins lipids, and carbohydrates fouling capillary UF membrane module; their ability to restore permeate fluxes and transmembrane pressure after cleaning/defouling was also investigated. Permeate volumes from this UF membrane module were analysed for protein, amino acids, lipids, and carbohydrates concentrations after fouling and defouling. Fouling was further characterized by standard blocking, cake filtration and pore blocking models using stirred UF cell and polyethersulphone membranes with MWCO of 30 000, 100 000 and 300 000. After characterization of fouling, polyethersulphone membranes with MWCO of 30 000 and 300 000 were defouled using the concentrated enzyme extract (100 mg ml). Enzyme activities at 200 mg/ml of enzyme concentration were 8.071 IU, 86.71 IU and 789.02 IU for proteases, lipases and α-glucosidases. The abattoir effluent contained 553 μg/ml of lipid, 301 μg/ml of protein, 141 μg/ml of total carbohydrate, and 0.63 μg/ml of total reducing sugars. Proteins, lipids and carbohydrates fouling polysulphone membranes after a day were removed by 23.4 %, when a dilute enzyme was used. A concentrated enzyme extract of 200 mg/ml was able to remove proteins, lipids and carbohydrates up to 5 days of fouling by 100 %, 82 %, 71 %, 68 % and 76 % respectively. Defouling of dynamically fouled capillary ultrafiltration membranes using sulphidogenic proteases was successful at pH 10, 37°C, within 1 hour. Sulphidogenic proteases activity was 2.1 U/ml and flux Recovery (FR %) was 64. Characterization of fouling revealed that proteins and lipids were major foulants while low concentration of carbohydrates fouled polyethersulphone membranes. Fouling followed standard blocking for 10 minutes in all the membranes; afterwards fouling adopted cake filtration model for membranes with 30 000 MWCO and pore blocking model for membranes with 300 000 MWCO. A concentration of 100 mg/ml of enzyme extract was able to remove fouling from membranes with MWCO of 30 000. Defouling membranes that followed pore blocking model i.e. 300 000 MWCO was not successful due to a mass transfer problem. From the results of defouling of 30 000 and 300 000 MWCO it was concluded that defouling of cake layer fouling (30 000 MWCO) was successful while defouling of pore blocking fouling was unsuccessful due to a mass transfer problem. The ratio of enzymes present in the enzyme extract when calculated based on enzymatic activity for proteases, lipases and α-glucosidases was 1.1 %, 11 % and 87.9 %. It was hypothesized that apart from proteases, lipases, α and β-glucosidases; phosphatases, sulphatases, amonipeptidases etc. from a sulphidogenic bioreactor clean or defoul cake layer fouling by organic foulants and pore blocking fouling provided the mass transfer problem is solved. However, concentration of enzymes from a sulphidogenic bioreactor has not been optimized yet. Other methods of concentrating the enzyme extract can be investigated for example use of organic solvents.
- Full Text:
- Date Issued: 2004
Justifiability as grounds for the review of labour arbitration proceedings
- Authors: Young, Kirsty Leigh
- Date: 2004
- Subjects: South Africa. Commission for Conciliation, Mediation and Arbitration Mediation and conciliation, Industrial -- South Africa Arbitration, Industrial -- South Africa Arbitration, Industrial -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3666 , http://hdl.handle.net/10962/d1003070
- Description: This thesis focuses on the review of labour arbitration awards given under the auspices of the following bodies: the Commission for Conciliation, Mediation and Arbitration ("CCMA"), bargaining councils, statutory councils, accredited private agencies and private arbitration tribunals. The general grounds of review applicable to the arbitration awards of each body are set out. Against this background, the case of Carephone (Pty) Ltd v Marcus NO & Others (1998) 19 ILJ 1425 (LAC) is analysed and the principles pertaining to the justifiability test are clarified. The judicial rationale for the application of the test to CCMA arbitration proceedings and criticisms of the test are then examined. Currently the justifiability test applies in the review of CCMA proceedings only, so the judicial reasoning for the rejection of justifiability as a ground for private arbitration review is examined. Three approaches are suggested for the application of the justifiability test in private arbitration review. First it is proposed that the Arbitration Act could be interpreted to include the justifiability test under the statutory review grounds. Failing the acceptance of this approach, the second submission is that arbitration agreements could be interpreted to include an implied term that the arbitrator is under a duty to give justifiable awards. A third suggestion is that the law should be developed by attaching an ex lege term to all arbitration agreements requiring arbitrators to give justifiable awards. In the final chapter, the requirement of justifiability in awards given under the auspices of collective bargaining agents and accredited private agencies highlights the incongruity in applying the justifiability test in CCMA arbitration review and in rejecting this test in private arbitration review.
- Full Text:
- Date Issued: 2004
- Authors: Young, Kirsty Leigh
- Date: 2004
- Subjects: South Africa. Commission for Conciliation, Mediation and Arbitration Mediation and conciliation, Industrial -- South Africa Arbitration, Industrial -- South Africa Arbitration, Industrial -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3666 , http://hdl.handle.net/10962/d1003070
- Description: This thesis focuses on the review of labour arbitration awards given under the auspices of the following bodies: the Commission for Conciliation, Mediation and Arbitration ("CCMA"), bargaining councils, statutory councils, accredited private agencies and private arbitration tribunals. The general grounds of review applicable to the arbitration awards of each body are set out. Against this background, the case of Carephone (Pty) Ltd v Marcus NO & Others (1998) 19 ILJ 1425 (LAC) is analysed and the principles pertaining to the justifiability test are clarified. The judicial rationale for the application of the test to CCMA arbitration proceedings and criticisms of the test are then examined. Currently the justifiability test applies in the review of CCMA proceedings only, so the judicial reasoning for the rejection of justifiability as a ground for private arbitration review is examined. Three approaches are suggested for the application of the justifiability test in private arbitration review. First it is proposed that the Arbitration Act could be interpreted to include the justifiability test under the statutory review grounds. Failing the acceptance of this approach, the second submission is that arbitration agreements could be interpreted to include an implied term that the arbitrator is under a duty to give justifiable awards. A third suggestion is that the law should be developed by attaching an ex lege term to all arbitration agreements requiring arbitrators to give justifiable awards. In the final chapter, the requirement of justifiability in awards given under the auspices of collective bargaining agents and accredited private agencies highlights the incongruity in applying the justifiability test in CCMA arbitration review and in rejecting this test in private arbitration review.
- Full Text:
- Date Issued: 2004
An empirical investigation of the extension of servqual to measure internal service quality in a motor vehicle manufacturing setting
- Authors: Booi, Arthur Mzwandile
- Date: 2004
- Subjects: Automobile industry and trade -- Quality control -- South Africa -- Eastern Cape Automobile industry and trade -- Customer services -- South Africa -- Eastern Cape Automobile industry and trade -- Quality control -- Statistical methods Customer services -- Quality control Automobile industry and trade -- Quality assurance -- South Africa -- Eastern Cape Consumer satisfaction Industrial productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:801 , http://hdl.handle.net/10962/d1006139
- Description: This research explores the role, which the construct, service quality plays in an internal marketing setting. This is achieved by evaluating the perceptions and expectations of the production department with regards to the service quality provided by the maintenance department of a South African motor vehicle manufacturer. This was done using the INTSERVQUAL instrument, which was found to be a reliable instrument for measuring internal service quality within this context. A positivist approach has been adopted in conducting this research. There are two main hypotheses for this study: the first hypothesis is concerned with the relationship between the overall internal service quality and the five dimensions of service quality namely: tangibles, empathy, reliability, responsiveness and reliability. The second hypothesis focuses on the relationship between the front line staff segments of the production department and the five dimensions of internal service quality. The results of this research suggest that the perceptions and expectations of internal service customer segments plays a major role in achieving internal service quality. In addition, the importance of the INTSERVQUAL instrument in measuring internal service quality within the motor vehicle manufacturing environment is confirmed.
- Full Text:
- Date Issued: 2004
- Authors: Booi, Arthur Mzwandile
- Date: 2004
- Subjects: Automobile industry and trade -- Quality control -- South Africa -- Eastern Cape Automobile industry and trade -- Customer services -- South Africa -- Eastern Cape Automobile industry and trade -- Quality control -- Statistical methods Customer services -- Quality control Automobile industry and trade -- Quality assurance -- South Africa -- Eastern Cape Consumer satisfaction Industrial productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:801 , http://hdl.handle.net/10962/d1006139
- Description: This research explores the role, which the construct, service quality plays in an internal marketing setting. This is achieved by evaluating the perceptions and expectations of the production department with regards to the service quality provided by the maintenance department of a South African motor vehicle manufacturer. This was done using the INTSERVQUAL instrument, which was found to be a reliable instrument for measuring internal service quality within this context. A positivist approach has been adopted in conducting this research. There are two main hypotheses for this study: the first hypothesis is concerned with the relationship between the overall internal service quality and the five dimensions of service quality namely: tangibles, empathy, reliability, responsiveness and reliability. The second hypothesis focuses on the relationship between the front line staff segments of the production department and the five dimensions of internal service quality. The results of this research suggest that the perceptions and expectations of internal service customer segments plays a major role in achieving internal service quality. In addition, the importance of the INTSERVQUAL instrument in measuring internal service quality within the motor vehicle manufacturing environment is confirmed.
- Full Text:
- Date Issued: 2004
The effect of commercialisation, privatisation and liberalisation on universal access in South Africa
- Gardner, Sean Patrick Newell
- Authors: Gardner, Sean Patrick Newell
- Date: 2004
- Subjects: Telkom (Firm : South Africa) , Telecommunication , Telecommunication -- South Africa , Privatization -- South Africa , Trade regulation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3431 , http://hdl.handle.net/10962/d1002885 , Telkom (Firm : South Africa) , Telecommunication , Telecommunication -- South Africa , Privatization -- South Africa , Trade regulation -- South Africa
- Description: From the 1990s onwards, significant developments have occurred in the international telecommunications sector that have affected the South African telecommunications industry and peoples’ access to the network. Rapid developments in Information and Communication Technologies and the reorganisation of telecommunications operators through commercialisation, privatisation and the effects of market liberalisation have resulted in monopoly operators moving away from their public service mandates. Globalisation and adherence to World Trade Organisation rules are causing operators to rebalance their tariffs closer to cost. Long-distance rates are decreasing while the cost of local calls is increasing. High-end users of telecommunications services are benefiting while low-end, largely residential users are being priced off the network. The end result is a negative effect on universal access to telecommunications services. This study examines the extent to which commercialisation, privatisation and liberalization are affecting the provision of telecommunications services and the government’s goal of achieving universal access in South Africa. Qualitative research methods were utilised to establish that the state owned operator, Telkom, has transformed itself from a public service operator to one that is fully commercialised and prepared for an Initial Public Offering and competition. Telkom no longer attempts to ensure that its tariffs are affordable for all people. However, positive developments presented themselves in the form of an increasingly competent regulator, a reorganised and dedicated Universal Service Agency, and the popularity of cellular telephony. The primary discovery of this study is that the liberalisation of the South African telecommunications sector cannot be assumed to have a negative effect on the provision of service. This study finds that liberalisation will most likely benefit the country through the role out of new infrastructure, the provision of new services and ultimately the reduction of those services themselves. In order for universal access to be achieved in this country the study recommends that the resources of the Independent Communications Authority of South Africa be enhanced to enable the regulator oversee the industry effectively. Secondly, the Universal Service Agency must provide clear definitions of universal access and universal service as well as manage the Universal Service Fund with greater efficiency. Lastly, the two bodies mentioned above must ensure that services are affordable for all people of this country.
- Full Text:
- Date Issued: 2004
- Authors: Gardner, Sean Patrick Newell
- Date: 2004
- Subjects: Telkom (Firm : South Africa) , Telecommunication , Telecommunication -- South Africa , Privatization -- South Africa , Trade regulation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3431 , http://hdl.handle.net/10962/d1002885 , Telkom (Firm : South Africa) , Telecommunication , Telecommunication -- South Africa , Privatization -- South Africa , Trade regulation -- South Africa
- Description: From the 1990s onwards, significant developments have occurred in the international telecommunications sector that have affected the South African telecommunications industry and peoples’ access to the network. Rapid developments in Information and Communication Technologies and the reorganisation of telecommunications operators through commercialisation, privatisation and the effects of market liberalisation have resulted in monopoly operators moving away from their public service mandates. Globalisation and adherence to World Trade Organisation rules are causing operators to rebalance their tariffs closer to cost. Long-distance rates are decreasing while the cost of local calls is increasing. High-end users of telecommunications services are benefiting while low-end, largely residential users are being priced off the network. The end result is a negative effect on universal access to telecommunications services. This study examines the extent to which commercialisation, privatisation and liberalization are affecting the provision of telecommunications services and the government’s goal of achieving universal access in South Africa. Qualitative research methods were utilised to establish that the state owned operator, Telkom, has transformed itself from a public service operator to one that is fully commercialised and prepared for an Initial Public Offering and competition. Telkom no longer attempts to ensure that its tariffs are affordable for all people. However, positive developments presented themselves in the form of an increasingly competent regulator, a reorganised and dedicated Universal Service Agency, and the popularity of cellular telephony. The primary discovery of this study is that the liberalisation of the South African telecommunications sector cannot be assumed to have a negative effect on the provision of service. This study finds that liberalisation will most likely benefit the country through the role out of new infrastructure, the provision of new services and ultimately the reduction of those services themselves. In order for universal access to be achieved in this country the study recommends that the resources of the Independent Communications Authority of South Africa be enhanced to enable the regulator oversee the industry effectively. Secondly, the Universal Service Agency must provide clear definitions of universal access and universal service as well as manage the Universal Service Fund with greater efficiency. Lastly, the two bodies mentioned above must ensure that services are affordable for all people of this country.
- Full Text:
- Date Issued: 2004
Research portfolio
- Authors: Bock, L J
- Date: 2004
- Subjects: Education -- Namibia Educational change -- Namibia Curriculum change -- Namibia College teachers -- Training of -- Namibia Geography -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1895 , http://hdl.handle.net/10962/d1006128
- Full Text:
- Date Issued: 2004
- Authors: Bock, L J
- Date: 2004
- Subjects: Education -- Namibia Educational change -- Namibia Curriculum change -- Namibia College teachers -- Training of -- Namibia Geography -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1895 , http://hdl.handle.net/10962/d1006128
- Full Text:
- Date Issued: 2004
Thermal and photostability studies of triprolidine hydrochloride and its mixtures with cyclodextrin and glucose
- Authors: Ndlebe, Vuyelwa Jacqueline
- Date: 2004
- Subjects: Antihistamines , Glucose , Cyclodextrins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4387 , http://hdl.handle.net/10962/d1005052 , Antihistamines , Glucose , Cyclodextrins
- Description: Triprolidine hydrochloride (C₁₉H₂₂N₂.HCl.H₂O) (TPH) is a well-known antihistamine drug. It melts between 118°C and 122°C and the amount of water present is 4.5 mass percent. TPH is reported as being photosensitive and must be stored in sealed, light-tight containers. The thermal stabilities of TPH and of 1:1 molar and 1:1 mass ratio physical mixtures of TPH with beta-cyclodextrin (BCD) and with glucose have been examined using DSC, TG and TG-FTIR, complemented by X-ray powder diffraction (XRD) and infrared spectroscopic (IR) studies. Thermal studies of the solid TPH/BCD mixtures indicated that interaction between the components occurs and it is possible that the TPH molecule may be least partially accommodated in the cavity of the BCD host molecule. XRD results support this indication of inclusion. The results for mixtures of TPH/glucose also suggest that there is interaction between the two components. The results of molecular modelling suggest that TPH is most likely to be accommodated in the BCD cavity as a neutral triprolidine molecule with the toluene portion of the molecule entering first. There is also an indication that the Z-isomer should be accommodated slightly more readily than the E-isomer. Photostability studies were done by irradiating thin layers of solid samples of TPH and its mixtures for various times at 40°C using an Atlas Sun test CPS lamp operating at 550 W h m⁻². An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants. The results obtained illustrate the general stability of TPH, especially in the solid state. Although the potential for isomerization to the pharmaceutically inactive Z-isomer exists, this transformation would require extreme light conditions. The study has also shown TPH to be compatible with both glucose and BCD, which are potential excipients both in solid and liquid dosage forms. The presents of these excipients in dosage forms will thus not adversely affect the stability and the therapeutic efficacy of TPH. . An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants.
- Full Text:
- Date Issued: 2004
- Authors: Ndlebe, Vuyelwa Jacqueline
- Date: 2004
- Subjects: Antihistamines , Glucose , Cyclodextrins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4387 , http://hdl.handle.net/10962/d1005052 , Antihistamines , Glucose , Cyclodextrins
- Description: Triprolidine hydrochloride (C₁₉H₂₂N₂.HCl.H₂O) (TPH) is a well-known antihistamine drug. It melts between 118°C and 122°C and the amount of water present is 4.5 mass percent. TPH is reported as being photosensitive and must be stored in sealed, light-tight containers. The thermal stabilities of TPH and of 1:1 molar and 1:1 mass ratio physical mixtures of TPH with beta-cyclodextrin (BCD) and with glucose have been examined using DSC, TG and TG-FTIR, complemented by X-ray powder diffraction (XRD) and infrared spectroscopic (IR) studies. Thermal studies of the solid TPH/BCD mixtures indicated that interaction between the components occurs and it is possible that the TPH molecule may be least partially accommodated in the cavity of the BCD host molecule. XRD results support this indication of inclusion. The results for mixtures of TPH/glucose also suggest that there is interaction between the two components. The results of molecular modelling suggest that TPH is most likely to be accommodated in the BCD cavity as a neutral triprolidine molecule with the toluene portion of the molecule entering first. There is also an indication that the Z-isomer should be accommodated slightly more readily than the E-isomer. Photostability studies were done by irradiating thin layers of solid samples of TPH and its mixtures for various times at 40°C using an Atlas Sun test CPS lamp operating at 550 W h m⁻². An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants. The results obtained illustrate the general stability of TPH, especially in the solid state. Although the potential for isomerization to the pharmaceutically inactive Z-isomer exists, this transformation would require extreme light conditions. The study has also shown TPH to be compatible with both glucose and BCD, which are potential excipients both in solid and liquid dosage forms. The presents of these excipients in dosage forms will thus not adversely affect the stability and the therapeutic efficacy of TPH. . An analytical method using HPLC was developed and validated to determine the amounts of any photodegradants. DSC, TG, FTIR, XRD and IR were also used examine the irradiated samples. XRD results showed that changes in the TPH crystal structure occurred during irradiation and that these changes increased with the time of irradiation. Irradiation for 20 hours with UV or exposure to sunlight showed the presence of degradants.
- Full Text:
- Date Issued: 2004
A phenological and bioclimatic analysis of honey yield in South Africa
- Authors: Illgner, Peter Mark
- Date: 2004
- Subjects: Bee culture -- South Africa -- Statistics Honeybee -- South Africa Bee culture -- South Africa -- Management Honey plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5813 , http://hdl.handle.net/10962/d1007153
- Description: This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.
- Full Text:
- Date Issued: 2004
- Authors: Illgner, Peter Mark
- Date: 2004
- Subjects: Bee culture -- South Africa -- Statistics Honeybee -- South Africa Bee culture -- South Africa -- Management Honey plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5813 , http://hdl.handle.net/10962/d1007153
- Description: This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.
- Full Text:
- Date Issued: 2004
A democratising South Africa?: an analysis of the 2004 national election
- Authors: Prudhomme, Leah Shianne
- Date: 2004
- Subjects: African National Congress , Elections -- South Africa , Voting -- South Africa , Democracy -- South Africa , Political parties -- South Africa , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2823 , http://hdl.handle.net/10962/d1003033 , African National Congress , Elections -- South Africa , Voting -- South Africa , Democracy -- South Africa , Political parties -- South Africa , South Africa -- Politics and government -- 1994-
- Description: Two of the post apartheid elections held in South Africa (1994, 1999) have been used as mechanisms to analyse and assess the extent to which the country’s transition from apartheid to a democratic dispensation is succeeding or not. The primary analytical focus of the 1994 and 1999 elections has revolved around the nature of the party system and voting behaviour. Basically, contestation has arisen over two primary and related issues: the dominance of the African National Congress (ANC) weighed against the weakness of opposition parties and the implications that this development has for effective democratic consolidation. Also, whether voting decisions based on divisive racial and ethnic identities that underlie electoral contests are pervasive enough to derail the process of democratisation. Generally, the primary conclusion has been that the unfolding pattern of South African electoral politics indicates sufficient grounds on which to doubt the prospects for effective democratic consolidation. This dissertation engages these debates with particular reference to the 2004 elections. In contrast to this pessimistic view of the prospects of successful democratisation in South Africa it upholds through an analysis of the 2004 elections the view that there is insufficient empirical evidence, to conclude that South Africa’s democratisation process is imperiled. It maintains that although there are problems related to the to the nature of the party system and some elements of voting behaviour there is enough countervailing evidence revealed by the 2004 election results that this does not present a substantially serious threat to the prospects of South Africa attaining a democratic society.
- Full Text:
- Date Issued: 2004
- Authors: Prudhomme, Leah Shianne
- Date: 2004
- Subjects: African National Congress , Elections -- South Africa , Voting -- South Africa , Democracy -- South Africa , Political parties -- South Africa , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2823 , http://hdl.handle.net/10962/d1003033 , African National Congress , Elections -- South Africa , Voting -- South Africa , Democracy -- South Africa , Political parties -- South Africa , South Africa -- Politics and government -- 1994-
- Description: Two of the post apartheid elections held in South Africa (1994, 1999) have been used as mechanisms to analyse and assess the extent to which the country’s transition from apartheid to a democratic dispensation is succeeding or not. The primary analytical focus of the 1994 and 1999 elections has revolved around the nature of the party system and voting behaviour. Basically, contestation has arisen over two primary and related issues: the dominance of the African National Congress (ANC) weighed against the weakness of opposition parties and the implications that this development has for effective democratic consolidation. Also, whether voting decisions based on divisive racial and ethnic identities that underlie electoral contests are pervasive enough to derail the process of democratisation. Generally, the primary conclusion has been that the unfolding pattern of South African electoral politics indicates sufficient grounds on which to doubt the prospects for effective democratic consolidation. This dissertation engages these debates with particular reference to the 2004 elections. In contrast to this pessimistic view of the prospects of successful democratisation in South Africa it upholds through an analysis of the 2004 elections the view that there is insufficient empirical evidence, to conclude that South Africa’s democratisation process is imperiled. It maintains that although there are problems related to the to the nature of the party system and some elements of voting behaviour there is enough countervailing evidence revealed by the 2004 election results that this does not present a substantially serious threat to the prospects of South Africa attaining a democratic society.
- Full Text:
- Date Issued: 2004
Price discovery, price behaviour, and efficiency of selected grain commodities traded on the agricultural products division of the JSE securities exchange
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
- Authors: Viljoen, Christo
- Date: 2004
- Subjects: Johannesburg Stock Exchange Stock exchanges -- South Africa International economic relations Primary commodities -- South Africa Grain trade -- South Africa Financial futures -- South Africa Price regulation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:952 , http://hdl.handle.net/10962/d1002686
- Description: Agricultural commodity derivatives were first introduced in South Africa in 1996 after the deregulation of the former marketing system. In the context of its proposed functions, namely price discovery and risk management, the question arose as to whether the futures market developed over time to performed its role efficiently. According to the Efficient Markets Hypothesis (EMH) an efficient market is one that accurately incorporates all information available at any point in time. The purpose of the research was to address the issue of price discovery efficiency, firstly, focusing on the weak-form methodology. Secondly, considering the behaviour of futures prices over time, the study addressed the concern of anomalies in daily returns – phenomena contradictory to the EMH by implication. Thirdly, as a means of defining the sources of inefficiency, the role of scheduled public information and its impact on futures prices was examined. Therefore, the primary objective of the research was to investigate and identify the main components of agricultural futures market inefficiency within the unique price formation structure of South African grain markets. The assessment of this problem is important in terms of evaluating the growth and development of the futures market for different grain commodities to date. The Exchange needs to review rules and regulations on a frequent basis in order to ensure proper functioning at all times especially in the case of a relatively new and fast growing market. The study contributed to the knowledge of understanding the price adjustment process and its implications for market efficiency in the context of the three grain markets considered. The weak-form efficiency was tested using a co-integration based model. Analysing daily spot and futures prices of white maize, yellow maize, and wheat, results indicated that all three markets were efficient and unbiased. Non-parametric tests revealed the significant presence of day-of-the-week and turn-of-the-month effects in the futures returns of the three commodities. Further non-parametric analyses suggested a high degree of uncertainty in futures returns around scheduled agricultural and macroeconomic information release dates also contributing significantly to the identified anomalies. It was concluded that (1) the markets’ ability to anticipate the contents of future information to be released, (2) the current skewed size distribution of broking members, (3) the significant role of the R/$ exchange rate in the price formation process of South African grains and, therefore, (4) the relationship to and influence of the broader economy enhanced the return effects (anomalies) creating opportunity for profitable arbitrage. This conclusion was mainly attributed to South Africa’s status as a price-taker in the world grain complex as well as the relatively short existence of the local agricultural futures markets.
- Full Text:
- Date Issued: 2004
Age, growth and yield-per-recruit analysis of ndunduma Diplotaxodon limnothrissa (Teleostei: Cichlidae), in the southeastern arm of Lake Malawi
- Authors: Kanyerere, Geoffrey Zantute
- Date: 2004
- Subjects: Fishes -- Nyasa, Lake , Cichlids -- Nyasa, Lake , Fishes -- Growth -- Nyasa, Lake , Fishes -- Age -- Nyasa, Lake , Fishery resources -- Malawi , Fishery management -- Malawi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5214 , http://hdl.handle.net/10962/d1005057 , Fishes -- Nyasa, Lake , Cichlids -- Nyasa, Lake , Fishes -- Growth -- Nyasa, Lake , Fishes -- Age -- Nyasa, Lake , Fishery resources -- Malawi , Fishery management -- Malawi
- Description: Diplotaxodon limnothrissa Turner (1995) is a widely distributed species occurring throughout Lake Malawi, extending from the surface to a depth of at least 220m. It is probably the most abundant cichlid in the lake with biomass estimates of around 87 000 tonnes in the pelagic zone alone. The species is exploited commercially in the southern part of the lake but since its inception the fishery has never been assessed. As such this study investigates some aspects of age and growth of the species besides applying a yield-per-recruit analysis to assess the status of the fishery. Analysis of sectioned sagittal otoliths revealed that D. limnothrissa is fast growing and relatively long-lived species, attaining ages in excess of 10 years. Growth in length was rapid in immature fish, with fish attaining almost half of their maximum size within their first year. Le ngth-at-age was described by the von Bertalanffy growth model with combined-sex growth described as Lt = 211.21(1-exp(- 0.24(t+1.36))) mm TL. Total, natural and fishing mortalities were estimated at 0.76 yr⁻¹, 0.31 yr⁻¹ and 0.45 yr⁻¹ respectively. Per-recruit analysis indicated that the D. limnothrissa stock in the southeast arm of the lake is fully exploited as indicated by the current spawner biomass-per-recruit ratios of 31-55% (SB/R)F=0. Modelling indicated that the current age-at-capture (2.67 years) is lower than the age at which yield is optimised (> 5 years) based on the F₀·₁ harvesting strategy. It is, therefore, recommended that the age-at-capture should be increased from 2.67 to 5 years to optimise yield.
- Full Text:
- Date Issued: 2004
- Authors: Kanyerere, Geoffrey Zantute
- Date: 2004
- Subjects: Fishes -- Nyasa, Lake , Cichlids -- Nyasa, Lake , Fishes -- Growth -- Nyasa, Lake , Fishes -- Age -- Nyasa, Lake , Fishery resources -- Malawi , Fishery management -- Malawi
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5214 , http://hdl.handle.net/10962/d1005057 , Fishes -- Nyasa, Lake , Cichlids -- Nyasa, Lake , Fishes -- Growth -- Nyasa, Lake , Fishes -- Age -- Nyasa, Lake , Fishery resources -- Malawi , Fishery management -- Malawi
- Description: Diplotaxodon limnothrissa Turner (1995) is a widely distributed species occurring throughout Lake Malawi, extending from the surface to a depth of at least 220m. It is probably the most abundant cichlid in the lake with biomass estimates of around 87 000 tonnes in the pelagic zone alone. The species is exploited commercially in the southern part of the lake but since its inception the fishery has never been assessed. As such this study investigates some aspects of age and growth of the species besides applying a yield-per-recruit analysis to assess the status of the fishery. Analysis of sectioned sagittal otoliths revealed that D. limnothrissa is fast growing and relatively long-lived species, attaining ages in excess of 10 years. Growth in length was rapid in immature fish, with fish attaining almost half of their maximum size within their first year. Le ngth-at-age was described by the von Bertalanffy growth model with combined-sex growth described as Lt = 211.21(1-exp(- 0.24(t+1.36))) mm TL. Total, natural and fishing mortalities were estimated at 0.76 yr⁻¹, 0.31 yr⁻¹ and 0.45 yr⁻¹ respectively. Per-recruit analysis indicated that the D. limnothrissa stock in the southeast arm of the lake is fully exploited as indicated by the current spawner biomass-per-recruit ratios of 31-55% (SB/R)F=0. Modelling indicated that the current age-at-capture (2.67 years) is lower than the age at which yield is optimised (> 5 years) based on the F₀·₁ harvesting strategy. It is, therefore, recommended that the age-at-capture should be increased from 2.67 to 5 years to optimise yield.
- Full Text:
- Date Issued: 2004
Equity in the South African legal system a critical ethnography
- Authors: Leiper, Jonathan
- Date: 2004
- Subjects: Court interpreting and translating -- South Africa , Language and languages -- Law and legislation -- South Africa , Translators -- Training of -- South Africa , Translators -- Legal status, laws, etc. -- South Africa , Law -- Translating -- South Africa , Law -- South Africa -- Language
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2355 , http://hdl.handle.net/10962/d1002637 , Court interpreting and translating -- South Africa , Language and languages -- Law and legislation -- South Africa , Translators -- Training of -- South Africa , Translators -- Legal status, laws, etc. -- South Africa , Law -- Translating -- South Africa , Law -- South Africa -- Language
- Description: This thesis focuses on the process of interpreting and the difficulties faced by interpreters in the Magistrates' Court in Grahamstown, South Africa. More particularly, the thesis seeks to establish whether the constitutional guarantee of language equity can be applied to the courts - given the numerous problems with interpreting. Respondents from different spheres of the legal profession were interviewed in order to ascertain their perspectives on the state of interpreting, problems that are encountered by interpreters and attitudes displayed by other members of the legal profession towards interpreters. The methodology used in the thesis is that of a critical ethnography. As such, the research also has a critical focus, seeking to determine the ideologies and interests of different ):articipants in the legal process. On the basis of the data collected, a number of conclusions are drawn. The first is that interpreting in South Africa is in trouble. The system of interpreting is beset by a number of different problems. This study describes four different types of problems that are faced by interpreters: linguistic problems, environmental problems, training and administrative issues, and poor status in the eyes of the other participants in the legal process. Together the cumulative effect of these problems is the undermining of the principle of equity in the justice system. Finally, the thesis provides various practical and achievable solutions to the problems outlined above, specifically those faced by interpreters. The researcher also critically evaluates the efforts and motives of the Department of Justice and Constitutional Development.
- Full Text:
- Date Issued: 2004
- Authors: Leiper, Jonathan
- Date: 2004
- Subjects: Court interpreting and translating -- South Africa , Language and languages -- Law and legislation -- South Africa , Translators -- Training of -- South Africa , Translators -- Legal status, laws, etc. -- South Africa , Law -- Translating -- South Africa , Law -- South Africa -- Language
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2355 , http://hdl.handle.net/10962/d1002637 , Court interpreting and translating -- South Africa , Language and languages -- Law and legislation -- South Africa , Translators -- Training of -- South Africa , Translators -- Legal status, laws, etc. -- South Africa , Law -- Translating -- South Africa , Law -- South Africa -- Language
- Description: This thesis focuses on the process of interpreting and the difficulties faced by interpreters in the Magistrates' Court in Grahamstown, South Africa. More particularly, the thesis seeks to establish whether the constitutional guarantee of language equity can be applied to the courts - given the numerous problems with interpreting. Respondents from different spheres of the legal profession were interviewed in order to ascertain their perspectives on the state of interpreting, problems that are encountered by interpreters and attitudes displayed by other members of the legal profession towards interpreters. The methodology used in the thesis is that of a critical ethnography. As such, the research also has a critical focus, seeking to determine the ideologies and interests of different ):articipants in the legal process. On the basis of the data collected, a number of conclusions are drawn. The first is that interpreting in South Africa is in trouble. The system of interpreting is beset by a number of different problems. This study describes four different types of problems that are faced by interpreters: linguistic problems, environmental problems, training and administrative issues, and poor status in the eyes of the other participants in the legal process. Together the cumulative effect of these problems is the undermining of the principle of equity in the justice system. Finally, the thesis provides various practical and achievable solutions to the problems outlined above, specifically those faced by interpreters. The researcher also critically evaluates the efforts and motives of the Department of Justice and Constitutional Development.
- Full Text:
- Date Issued: 2004
Over-expression, purification and biochemical characterization of DOXP reductoisomerase and the rational design of novel anti-malarial drugs
- Authors: Tanner, Delia Caroline
- Date: 2004
- Subjects: Malaria -- Prevention , Malaria -- Drug therapy , Antimalarials -- Therapeutic use , Proteins -- Purification , Amino acids -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3931 , http://hdl.handle.net/10962/d1003990 , Malaria -- Prevention , Malaria -- Drug therapy , Antimalarials -- Therapeutic use , Proteins -- Purification , Amino acids -- Analysis
- Description: Malaria poses the greatest threat of all parasites to human life. Current vaccines and efficacious drugs are available however their use is limited due to toxicity, emergence of drug resistance, and cost. The discovery of an alternative pathway of isoprenoid biosynthesis, the non-mevalonate pathway, within the malarial parasite has resulted in development of novel anti-malarial drugs. 1-Deoxy-D-xylulose-5-phosphate (DOXP) reductoisomerase, the second enzyme in this pathway, is responsible for the synthesis of 2-C-methyl-D-erythritol 4-phosphate (MEP) in an intramolecular rearrangement step followed by a reduction process involving NADPH as a hydrogen donor and divalent cations as co-factors. Fosmidomycin and FR900098 have been identified as inhibitors of DOXP reductoisomerase. However, they lack clinical efficacy. In this investigation recombinant DOXP reductoisomerase from Escherichia coli (EcDXR) and Plasmodium falciparum (pfDXR) were biochemically characterized as potential targets for inhibition. (His)6-EcDXR was successfully purified using nickel-chelate affinity chromatography with a specific activity of 1.77 μmoles/min/mg and Km value 282 μM. Utilizing multiple sequence alignment, previous structural data predictions and homology modeling approaches, critical active site amino acid residues were identified and their role in the catalytic activity investigated utilizing site-directed mutagenesis techniques. We have shown evidence that suggests that Trp212 and Met214 interact to maintain the active site architecture and hydrophobic interactions necessary for substrate binding, cofactor binding and enzyme activity. Replacement of Trp212 with Tyr, Phe, and Leu reduced specific activity relative to EcDXR. EcDXR(W212F) and EcDXR(W212Y) had an increased Km relative to EcDXR indicative of loss in affinity toward DOXP, whereas EcDXR(W212L) had a lower Km of ~8 μM indicative of increased affinity for DOXP. The W212L substitution possibly removed contacts necessary for full catalytic activity, but could be considered a non-disruptive substitution in that it maintained active site architecture sufficient for DOXP reductoisomerase activity. EcDXR(M214I) had 36-fold reduced enzyme activity relative to EcDXR, while its Km (~8 μM) was found to be lower than that of EcDXR. This suggested that the M214I substitution had maintained (perhaps improved) substrate and active site architecture, but may have perturbed interactions with NADPH. Rational drug design strategies and docking methods have been utilized in the development of furan derivatives as DOXP reductoisomerase inhibitors, and the synthesis of phosphorylated derivatives (5) and (6) has been achieved. Future inhibitor studies using these novel potential DOXP reductoisomerase inhibitors may lead to the development of effective anti-malarial drug candidates.
- Full Text:
- Date Issued: 2004
- Authors: Tanner, Delia Caroline
- Date: 2004
- Subjects: Malaria -- Prevention , Malaria -- Drug therapy , Antimalarials -- Therapeutic use , Proteins -- Purification , Amino acids -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3931 , http://hdl.handle.net/10962/d1003990 , Malaria -- Prevention , Malaria -- Drug therapy , Antimalarials -- Therapeutic use , Proteins -- Purification , Amino acids -- Analysis
- Description: Malaria poses the greatest threat of all parasites to human life. Current vaccines and efficacious drugs are available however their use is limited due to toxicity, emergence of drug resistance, and cost. The discovery of an alternative pathway of isoprenoid biosynthesis, the non-mevalonate pathway, within the malarial parasite has resulted in development of novel anti-malarial drugs. 1-Deoxy-D-xylulose-5-phosphate (DOXP) reductoisomerase, the second enzyme in this pathway, is responsible for the synthesis of 2-C-methyl-D-erythritol 4-phosphate (MEP) in an intramolecular rearrangement step followed by a reduction process involving NADPH as a hydrogen donor and divalent cations as co-factors. Fosmidomycin and FR900098 have been identified as inhibitors of DOXP reductoisomerase. However, they lack clinical efficacy. In this investigation recombinant DOXP reductoisomerase from Escherichia coli (EcDXR) and Plasmodium falciparum (pfDXR) were biochemically characterized as potential targets for inhibition. (His)6-EcDXR was successfully purified using nickel-chelate affinity chromatography with a specific activity of 1.77 μmoles/min/mg and Km value 282 μM. Utilizing multiple sequence alignment, previous structural data predictions and homology modeling approaches, critical active site amino acid residues were identified and their role in the catalytic activity investigated utilizing site-directed mutagenesis techniques. We have shown evidence that suggests that Trp212 and Met214 interact to maintain the active site architecture and hydrophobic interactions necessary for substrate binding, cofactor binding and enzyme activity. Replacement of Trp212 with Tyr, Phe, and Leu reduced specific activity relative to EcDXR. EcDXR(W212F) and EcDXR(W212Y) had an increased Km relative to EcDXR indicative of loss in affinity toward DOXP, whereas EcDXR(W212L) had a lower Km of ~8 μM indicative of increased affinity for DOXP. The W212L substitution possibly removed contacts necessary for full catalytic activity, but could be considered a non-disruptive substitution in that it maintained active site architecture sufficient for DOXP reductoisomerase activity. EcDXR(M214I) had 36-fold reduced enzyme activity relative to EcDXR, while its Km (~8 μM) was found to be lower than that of EcDXR. This suggested that the M214I substitution had maintained (perhaps improved) substrate and active site architecture, but may have perturbed interactions with NADPH. Rational drug design strategies and docking methods have been utilized in the development of furan derivatives as DOXP reductoisomerase inhibitors, and the synthesis of phosphorylated derivatives (5) and (6) has been achieved. Future inhibitor studies using these novel potential DOXP reductoisomerase inhibitors may lead to the development of effective anti-malarial drug candidates.
- Full Text:
- Date Issued: 2004
Spirituality in the fiction of Henry Rider Haggard
- Authors: Senior, John
- Date: 2004
- Subjects: Haggard, H. Rider (Henry Rider), 1856-1925 -- Religion Haggard, H. Rider (Henry Rider), 1856-1925 -- Criticism and interpretation Religion in literature Spirituality in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2209 , http://hdl.handle.net/10962/d1002252
- Description: Neither an unquestioning support for British imperialism nor a personal pre-Jungian philosophy were the driving forces behind Rider Haggard’s beliefs or his literature. These two concerns were secondary to the author’s fascination with the supernatural, a theme prominent in his era, but less so in our own. A declining faith in European religion provided the dominant focal point in Haggard’s work. Although there are important overtones of imperial concern and indeed points of Jungian significance in the texts, these are generally subservient to an intensive wide-ranging spiritual discourse. The place of Haggard’s work in history and its literary merit are thus misunderstood when his spiritualism is not taken into account. No analysis of the author’s work can be complete without first coming to terms with his spiritual ideas and then with their impact on other topics of significance to both the author and audiences of his day. The spiritual or religious aspect of his writing has been largely ignored because of its subtle nature and its relative unfashionability throughout most of the twentieth century in the critical and intellectual climate of the Western world. However, in the Victorian era, under the materialist impact of Darwin, Marx and industrialization, Europe's Christian God was pushed from centre stage, creating widespread spiritual hunger and anguish. In the resulting religious vacuum Haggard's overtures were of particular significance to his audience. In fact, when considered in terms of his immense contemporary popularity, the pervasive presence of spirituality throughout Haggard's works and in his personal writing gives some indication of the subject's enormous importance not only to the author, but to late Victorian society as a whole. In light of this Victorian significance, the spiritual element rises, by its constant presence and persistent foregrounding, to subvert not only the imperial and the Jungian, but even Haggard's overt adventure text by dealing directly with the underlying metaphysical crisis in Western society.
- Full Text:
- Date Issued: 2004
- Authors: Senior, John
- Date: 2004
- Subjects: Haggard, H. Rider (Henry Rider), 1856-1925 -- Religion Haggard, H. Rider (Henry Rider), 1856-1925 -- Criticism and interpretation Religion in literature Spirituality in literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2209 , http://hdl.handle.net/10962/d1002252
- Description: Neither an unquestioning support for British imperialism nor a personal pre-Jungian philosophy were the driving forces behind Rider Haggard’s beliefs or his literature. These two concerns were secondary to the author’s fascination with the supernatural, a theme prominent in his era, but less so in our own. A declining faith in European religion provided the dominant focal point in Haggard’s work. Although there are important overtones of imperial concern and indeed points of Jungian significance in the texts, these are generally subservient to an intensive wide-ranging spiritual discourse. The place of Haggard’s work in history and its literary merit are thus misunderstood when his spiritualism is not taken into account. No analysis of the author’s work can be complete without first coming to terms with his spiritual ideas and then with their impact on other topics of significance to both the author and audiences of his day. The spiritual or religious aspect of his writing has been largely ignored because of its subtle nature and its relative unfashionability throughout most of the twentieth century in the critical and intellectual climate of the Western world. However, in the Victorian era, under the materialist impact of Darwin, Marx and industrialization, Europe's Christian God was pushed from centre stage, creating widespread spiritual hunger and anguish. In the resulting religious vacuum Haggard's overtures were of particular significance to his audience. In fact, when considered in terms of his immense contemporary popularity, the pervasive presence of spirituality throughout Haggard's works and in his personal writing gives some indication of the subject's enormous importance not only to the author, but to late Victorian society as a whole. In light of this Victorian significance, the spiritual element rises, by its constant presence and persistent foregrounding, to subvert not only the imperial and the Jungian, but even Haggard's overt adventure text by dealing directly with the underlying metaphysical crisis in Western society.
- Full Text:
- Date Issued: 2004
An empirical study of client satisfaction with service recovery within a South African banking institution
- Authors: Davies, Gareth M
- Date: 2004
- Subjects: First National Bank of Southern Africa Banks and banking -- South Africa Bank management -- South Africa Financial services industry -- South Africa Banks and banking -- Customer services -- South Africa Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:725 , http://hdl.handle.net/10962/d1003845
- Description: In many industries, service is the critical determinant of success or failure. Service failure is almost inevitable, and this has the potential for the organisation to lose its customer. However, if implemented successfully, Service Recovery can rectify the breakdown in service, and turn angry, frustrated customers into loyal ones. Service Recovery is vital for profitability, especially for companies operating in the services market, like First National Bank (FNB). Unfortunately, few service firms know how satisfied customers are with their Service Recovery efforts, and FNB is no exception. This study attempted to rectify the situation, to ensure that the bank does not fail its customers a second time. The major focus of the study is to assess client satisfaction with Service Recovery (SR) from FNB. By using the RECOVSAT instrument (developed by Boshoff in 1999), the study aims to establish how effective FNB was in terms of the six dimensions of SR, namely communication, empowerment, feedback, atonement, explanation, and tangibles. The relationship between each of the dimensions and customer satisfaction, as well as between customer satisfaction and loyalty, was measured, and a hypothesis for each relationship rejected or accepted. The empirical results show that, from 702 complainants, a RECOVSAT score of 68% was computed, which could be regarded as only satisfactory. The dimensions of communication, explanation, atonement, and empowerment, had the strongest positive correlation with customer satisfaction, while feedback and tangibles, although positively correlated, were not statistically significant, and thus not as important as the first four dimensions. FNB performed best on tangibles (81%), then communication (75%), explanation (70%), atonement (68%), empowerment (62%), and lastly feedback (51%). The study reinforced the view that customer satisfaction is positively related to loyalty. Other findings were that, administration and errors were the most frequent complaints, followed by pricing, fees, and interest, while time delays/waiting were the third most numerous. Over 54% of complainants had been with the bank for over 10 years, which could be a problem if the customers had left the bank, as the profitability of a customer generally increases with time. Age and gender did not appear to be factors that influenced behaviour of complainants. In terms of the managerial implications, it is recommended that FNB implement a Customer-Complaint-Handling (CCH) system that is both national and inter-group. The bank should also focus on empowering employees, improving communication skills, explaining to customers why the problem occurred, apologising, and offering some atonement. By adopting the recommendations, FNB should improve their service recovery, and as a consequence, their customer satisfaction and loyalty, and profitability should also increase.
- Full Text:
- Date Issued: 2004
- Authors: Davies, Gareth M
- Date: 2004
- Subjects: First National Bank of Southern Africa Banks and banking -- South Africa Bank management -- South Africa Financial services industry -- South Africa Banks and banking -- Customer services -- South Africa Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:725 , http://hdl.handle.net/10962/d1003845
- Description: In many industries, service is the critical determinant of success or failure. Service failure is almost inevitable, and this has the potential for the organisation to lose its customer. However, if implemented successfully, Service Recovery can rectify the breakdown in service, and turn angry, frustrated customers into loyal ones. Service Recovery is vital for profitability, especially for companies operating in the services market, like First National Bank (FNB). Unfortunately, few service firms know how satisfied customers are with their Service Recovery efforts, and FNB is no exception. This study attempted to rectify the situation, to ensure that the bank does not fail its customers a second time. The major focus of the study is to assess client satisfaction with Service Recovery (SR) from FNB. By using the RECOVSAT instrument (developed by Boshoff in 1999), the study aims to establish how effective FNB was in terms of the six dimensions of SR, namely communication, empowerment, feedback, atonement, explanation, and tangibles. The relationship between each of the dimensions and customer satisfaction, as well as between customer satisfaction and loyalty, was measured, and a hypothesis for each relationship rejected or accepted. The empirical results show that, from 702 complainants, a RECOVSAT score of 68% was computed, which could be regarded as only satisfactory. The dimensions of communication, explanation, atonement, and empowerment, had the strongest positive correlation with customer satisfaction, while feedback and tangibles, although positively correlated, were not statistically significant, and thus not as important as the first four dimensions. FNB performed best on tangibles (81%), then communication (75%), explanation (70%), atonement (68%), empowerment (62%), and lastly feedback (51%). The study reinforced the view that customer satisfaction is positively related to loyalty. Other findings were that, administration and errors were the most frequent complaints, followed by pricing, fees, and interest, while time delays/waiting were the third most numerous. Over 54% of complainants had been with the bank for over 10 years, which could be a problem if the customers had left the bank, as the profitability of a customer generally increases with time. Age and gender did not appear to be factors that influenced behaviour of complainants. In terms of the managerial implications, it is recommended that FNB implement a Customer-Complaint-Handling (CCH) system that is both national and inter-group. The bank should also focus on empowering employees, improving communication skills, explaining to customers why the problem occurred, apologising, and offering some atonement. By adopting the recommendations, FNB should improve their service recovery, and as a consequence, their customer satisfaction and loyalty, and profitability should also increase.
- Full Text:
- Date Issued: 2004