The influence of a methylated-β-Cyclodextrin on the solubility and photostability of midazolam in aqueous solution
- Authors: Lebete, Mosimotsana Leah
- Date: 2001 , 2013-04-26
- Subjects: Midazolam -- Solubility
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3823 , http://hdl.handle.net/10962/d1005923 , Midazolam -- Solubility
- Description: Midazolam, used clinically as an anticonvulsant, anxiolytic, muscle relaxant and sedative is a photolabile imidazo-benzodiazepine which is marketed under the trade names Dormicum® and Hypnovel® as tablets and injectables. Because of an aqueous solubility of < 0.1 mg/ml above pH 4, the preparation of aqueous dosage formulations near physiological pH, requires a solubilizer. The aim of this study was thus to prepare a 10 mg/ml midazolam aqueous solution for topical application using randomly-methylated-pcyclodextrin (RAMEB), considered to be a suitable candidate as a solubilizer because of its absorption enhancing properties, and to investigate its effect on both the solubility and the photostability of midazolam. Solubility studies of midazolam (excess of 15 mg/ml) in the presence of 0, 5,10,20, 30% m/v of RAMEB at pH 5.0 and pH 5.8 (phosphate buffer) were undertaken and the results analyzed using a UV method validated for linearity, accuracy, precision and specificity. A stability-indicating HPLC method was developed and validated (precision and accuracy, linearity, range, limit of quantitation, specificity, robustness and ruggedness) for application to kinetic photostability studies and the identification of photodegradants by LC-MS. Forced degradation studies were carried out at concentrations of 0.5 mg/ml of midazolam instead of the target concentration of 10 mg/ml because of the acceleratory effect of the decreased concentration on the rate of photodegradation. The solutions of midazolam with and without RAMEB were irradiated at 550 W/m² for 12 hrs in order to degrade the drug to ± 10% of the original concentration. The UV method proved to be valid in terms of linearity with a correlation coefficient of 0.9998, precise and accurate, and specific for the determination of midazolam in the presence of RAMEB. The results of the phase solubility studies indicated that desired solubility of 10 mg/ml was achieved with 30% m/v RAMEB at pH 5.0. RAMEB slightly decreased the photostability of midazolam, the rate constants being 0.137 and 0.154 hr⁻¹ in the absence and presence of RAMEB, respectively. LC-MS analysis revealed that one of the major photoproducts in the presence and absence of RAMEB was N-desalkylflurazepam, a starting material in the synthesis of midazolam. RAMEB inhibited formation of some photoproducts and introduced two new photoproducts, a dimer and an addition product. The difference in the nature of these photoproducts formed may be attributed to the ability of RAMEB to provide conformational control and to stabilize free radicals. Although RAMEB improved the solubility of midazolam to the target concentration, photostability is decreased with the presence of different photoproducts. These studies have however provided information on the overall photostability of midazolam, the identity of its photodegradants and the photodegradation pathway in the presence and absence of RAMEB, and may be used for further method development and validation for the analysis of aqueous dosage forms containing RAMEB as a solubilizer. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2001
- Authors: Lebete, Mosimotsana Leah
- Date: 2001 , 2013-04-26
- Subjects: Midazolam -- Solubility
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3823 , http://hdl.handle.net/10962/d1005923 , Midazolam -- Solubility
- Description: Midazolam, used clinically as an anticonvulsant, anxiolytic, muscle relaxant and sedative is a photolabile imidazo-benzodiazepine which is marketed under the trade names Dormicum® and Hypnovel® as tablets and injectables. Because of an aqueous solubility of < 0.1 mg/ml above pH 4, the preparation of aqueous dosage formulations near physiological pH, requires a solubilizer. The aim of this study was thus to prepare a 10 mg/ml midazolam aqueous solution for topical application using randomly-methylated-pcyclodextrin (RAMEB), considered to be a suitable candidate as a solubilizer because of its absorption enhancing properties, and to investigate its effect on both the solubility and the photostability of midazolam. Solubility studies of midazolam (excess of 15 mg/ml) in the presence of 0, 5,10,20, 30% m/v of RAMEB at pH 5.0 and pH 5.8 (phosphate buffer) were undertaken and the results analyzed using a UV method validated for linearity, accuracy, precision and specificity. A stability-indicating HPLC method was developed and validated (precision and accuracy, linearity, range, limit of quantitation, specificity, robustness and ruggedness) for application to kinetic photostability studies and the identification of photodegradants by LC-MS. Forced degradation studies were carried out at concentrations of 0.5 mg/ml of midazolam instead of the target concentration of 10 mg/ml because of the acceleratory effect of the decreased concentration on the rate of photodegradation. The solutions of midazolam with and without RAMEB were irradiated at 550 W/m² for 12 hrs in order to degrade the drug to ± 10% of the original concentration. The UV method proved to be valid in terms of linearity with a correlation coefficient of 0.9998, precise and accurate, and specific for the determination of midazolam in the presence of RAMEB. The results of the phase solubility studies indicated that desired solubility of 10 mg/ml was achieved with 30% m/v RAMEB at pH 5.0. RAMEB slightly decreased the photostability of midazolam, the rate constants being 0.137 and 0.154 hr⁻¹ in the absence and presence of RAMEB, respectively. LC-MS analysis revealed that one of the major photoproducts in the presence and absence of RAMEB was N-desalkylflurazepam, a starting material in the synthesis of midazolam. RAMEB inhibited formation of some photoproducts and introduced two new photoproducts, a dimer and an addition product. The difference in the nature of these photoproducts formed may be attributed to the ability of RAMEB to provide conformational control and to stabilize free radicals. Although RAMEB improved the solubility of midazolam to the target concentration, photostability is decreased with the presence of different photoproducts. These studies have however provided information on the overall photostability of midazolam, the identity of its photodegradants and the photodegradation pathway in the presence and absence of RAMEB, and may be used for further method development and validation for the analysis of aqueous dosage forms containing RAMEB as a solubilizer. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2001
The identification of operations strategies based on business principles that will enhance the public sector's ability to retain its client departments
- Authors: Davids, Shahied
- Date: 2001
- Subjects: Eastern Cape (South Africa) -- Public Works Department , Customer services
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10941 , http://hdl.handle.net/10948/d1006192 , Eastern Cape (South Africa) -- Public Works Department , Customer services
- Description: The research problem addressed in this study was to identify operational strategies that will enhance the ability of National Public Works Department (NPWD) of the Eastern Cape to retain its Client Departments. Privatisation has lead to performance management becoming essential to satisfy the client departments needs and requirements. In order to identify operational strategies which will enhance NPWD’s operation’s performance, questionnaires with relevant operation questions were used as well as a brain-writing session. The findings of the literature survey clearly highlight the specific areas where attention is required for improvements.
- Full Text:
- Date Issued: 2001
- Authors: Davids, Shahied
- Date: 2001
- Subjects: Eastern Cape (South Africa) -- Public Works Department , Customer services
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10941 , http://hdl.handle.net/10948/d1006192 , Eastern Cape (South Africa) -- Public Works Department , Customer services
- Description: The research problem addressed in this study was to identify operational strategies that will enhance the ability of National Public Works Department (NPWD) of the Eastern Cape to retain its Client Departments. Privatisation has lead to performance management becoming essential to satisfy the client departments needs and requirements. In order to identify operational strategies which will enhance NPWD’s operation’s performance, questionnaires with relevant operation questions were used as well as a brain-writing session. The findings of the literature survey clearly highlight the specific areas where attention is required for improvements.
- Full Text:
- Date Issued: 2001
The goddess, the witch and the bitch : three studies in the perception of women
- Authors: Hare, Nicola Tracy
- Date: 2001
- Subjects: Feminism in literature , Women's rights in literature , Feminism and literature , Patriarchy in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10986 , http://hdl.handle.net/10948/278 , Feminism in literature , Women's rights in literature , Feminism and literature , Patriarchy in literature
- Description: In the minds of many people all over the world, women are ‘second class citizens’, standing accused of the downfall of mankind ever since Eve allegedly ate the apple. Even amongst those who do not openly denigrate women, there are many who do so in other, more subtle ways even if they are unaware of it. This study proposes to challenge such a view of women by exposing the ways in which perceptions of women are constructed by society, which frequently wants to maintain the status quo of male dominance. This study employs a feminist approach in examining this gynocentric theme, along with cultural studies which, with its focus on power relations and ways of decentring power structures, is also clearly of use. In addition, this multidisciplinary approach of cultural studies offers the possibility of studying literary texts as well as popular culture. Three specific time periods are examined, with a view to uncovering negative perceptions of women and ways that women can resist such attempts to control them. In chapter one, the focus turns to contemporary perceptions of prehistoric women and the ways that so-called ‘objective’ science has failed to represent women accurately. Similarly, ‘objective’ accounts of Goddess-worship – which frequently fail to examine this phenomenon adequately – are revisited. Alice Walker’s The Temple of My Familiar (1989) is discussed as a text which acts as a site of resistance to societally-informed perceptions. Chapter two continues this investigation by turning to the concept of the witch and its maligned association with women. Woman and witchcraft, having been associated for centuries, are investigated as a pairing which frequently results because iii of attempts to control women by androcentric society. In such situations, the practising of witchcraft can actually become a form of resistance to patriarchy. The pernicious effect of society’s need to purge itself – by witch hunts – of witches is also investigated. The Devil’s Chimney (1997) by Anne Landsman and “The prophetess” (1994) by Njabulo S. Ndebele are discussed as texts which examine fictionalised South African versions of this phenomenon. Sinead O’Connor, the Irish singer, is the ‘bitch’ discussed in chapter three. She is examined as a woman who offers strong and on-going resistance to patriarchal ways of thinking which would ‘box’ women in. This singer refuses to accept societal roles which are offered to women and so offers means of resistance to patriarchy, many of which are discussed in this chapter. This study concludes that it is the responsibility of women to resist patriarchy and to define roles for themselves. The three chapters examine various means of resistance and offer women insight into the forms of opposition they themselves can take.
- Full Text:
- Date Issued: 2001
- Authors: Hare, Nicola Tracy
- Date: 2001
- Subjects: Feminism in literature , Women's rights in literature , Feminism and literature , Patriarchy in literature
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:10986 , http://hdl.handle.net/10948/278 , Feminism in literature , Women's rights in literature , Feminism and literature , Patriarchy in literature
- Description: In the minds of many people all over the world, women are ‘second class citizens’, standing accused of the downfall of mankind ever since Eve allegedly ate the apple. Even amongst those who do not openly denigrate women, there are many who do so in other, more subtle ways even if they are unaware of it. This study proposes to challenge such a view of women by exposing the ways in which perceptions of women are constructed by society, which frequently wants to maintain the status quo of male dominance. This study employs a feminist approach in examining this gynocentric theme, along with cultural studies which, with its focus on power relations and ways of decentring power structures, is also clearly of use. In addition, this multidisciplinary approach of cultural studies offers the possibility of studying literary texts as well as popular culture. Three specific time periods are examined, with a view to uncovering negative perceptions of women and ways that women can resist such attempts to control them. In chapter one, the focus turns to contemporary perceptions of prehistoric women and the ways that so-called ‘objective’ science has failed to represent women accurately. Similarly, ‘objective’ accounts of Goddess-worship – which frequently fail to examine this phenomenon adequately – are revisited. Alice Walker’s The Temple of My Familiar (1989) is discussed as a text which acts as a site of resistance to societally-informed perceptions. Chapter two continues this investigation by turning to the concept of the witch and its maligned association with women. Woman and witchcraft, having been associated for centuries, are investigated as a pairing which frequently results because iii of attempts to control women by androcentric society. In such situations, the practising of witchcraft can actually become a form of resistance to patriarchy. The pernicious effect of society’s need to purge itself – by witch hunts – of witches is also investigated. The Devil’s Chimney (1997) by Anne Landsman and “The prophetess” (1994) by Njabulo S. Ndebele are discussed as texts which examine fictionalised South African versions of this phenomenon. Sinead O’Connor, the Irish singer, is the ‘bitch’ discussed in chapter three. She is examined as a woman who offers strong and on-going resistance to patriarchal ways of thinking which would ‘box’ women in. This singer refuses to accept societal roles which are offered to women and so offers means of resistance to patriarchy, many of which are discussed in this chapter. This study concludes that it is the responsibility of women to resist patriarchy and to define roles for themselves. The three chapters examine various means of resistance and offer women insight into the forms of opposition they themselves can take.
- Full Text:
- Date Issued: 2001
The gift of music
- Authors: Thomas, Cornelius
- Date: 2001
- Subjects: Maqhula, Abe Dludlu, Jimmy Guitarists -- South Africa Jazz musicians -- South Africa
- Type: article
- Identifier: http://hdl.handle.net/10962/32826 , vital:24085 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , MS 20 019
- Description: Photocopied article from the newspaper The Daily Dispatch about handing over of a guitar which was bought buy Jimmy Dludlu as a gift to Abe "Kruger" Maqhula
- Full Text:
- Date Issued: 2001
- Authors: Thomas, Cornelius
- Date: 2001
- Subjects: Maqhula, Abe Dludlu, Jimmy Guitarists -- South Africa Jazz musicians -- South Africa
- Type: article
- Identifier: http://hdl.handle.net/10962/32826 , vital:24085 , This image is held at the Cory Library for Humanities Research at Rhodes University. For further information contact cory@ru.ac.za. The digitisation of this image was made possible through a generous grant received from the Andrew W. Mellon Foundation 2014-2017. , MS 20 019
- Description: Photocopied article from the newspaper The Daily Dispatch about handing over of a guitar which was bought buy Jimmy Dludlu as a gift to Abe "Kruger" Maqhula
- Full Text:
- Date Issued: 2001
The garden as a metaphor for paradise
- Authors: Adlard, Michelle Catherine
- Date: 2001
- Subjects: Paradise in art , Garden of paradise , Gardens -- Design -- Early works to 1800
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2391 , http://hdl.handle.net/10962/d1002187 , Paradise in art , Garden of paradise , Gardens -- Design -- Early works to 1800
- Description: In this half thesis the use of the garden as a metaphor for paradise has been explored. The English word “ paradise“ was derived from the Greek word “ paradeisos” which in turn was derived from the Old Avestana “ pairi-daeza,” meaning an enclosure. In Ancient Persia the concept applied to an enclosed garden in the modern sense of the word. For this reason the thesis begins with an examination of the development of the garden in this desert region. A more-or-less continuous chain of development in both the physical and allegorical nature of the garden is traced through history from these Ancient Persian beginnings to the height of Mughal architecture (epitomised by the Taj Mahal), by way of the Muslim expansion through Central Asia and Europe. While the core elements of garden design were set in Ancient Persian times, and recur throughout the period studied, the impact of Islam on the local Persian culture brought about a new development of allegorical meaning associated with the garden. This allegorical development reached its apex, too, in the Taj Mahal in which, it is argued, the metaphorical representation of paradise in the garden tomb was made astonishingly explicit. The research for this mini thesis was gathered from secondary sources, including many published books and academic papers, photographic and diagrammatic evidence of extant ancient gardens, and reproductions of carpet designs.
- Full Text:
- Date Issued: 2001
- Authors: Adlard, Michelle Catherine
- Date: 2001
- Subjects: Paradise in art , Garden of paradise , Gardens -- Design -- Early works to 1800
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2391 , http://hdl.handle.net/10962/d1002187 , Paradise in art , Garden of paradise , Gardens -- Design -- Early works to 1800
- Description: In this half thesis the use of the garden as a metaphor for paradise has been explored. The English word “ paradise“ was derived from the Greek word “ paradeisos” which in turn was derived from the Old Avestana “ pairi-daeza,” meaning an enclosure. In Ancient Persia the concept applied to an enclosed garden in the modern sense of the word. For this reason the thesis begins with an examination of the development of the garden in this desert region. A more-or-less continuous chain of development in both the physical and allegorical nature of the garden is traced through history from these Ancient Persian beginnings to the height of Mughal architecture (epitomised by the Taj Mahal), by way of the Muslim expansion through Central Asia and Europe. While the core elements of garden design were set in Ancient Persian times, and recur throughout the period studied, the impact of Islam on the local Persian culture brought about a new development of allegorical meaning associated with the garden. This allegorical development reached its apex, too, in the Taj Mahal in which, it is argued, the metaphorical representation of paradise in the garden tomb was made astonishingly explicit. The research for this mini thesis was gathered from secondary sources, including many published books and academic papers, photographic and diagrammatic evidence of extant ancient gardens, and reproductions of carpet designs.
- Full Text:
- Date Issued: 2001
The experiences of couples in relationships characterized by alcohol dependency
- Authors: Mgilane, Nomgcobo Eunice
- Date: 2001
- Subjects: Alcoholism -- South Africa Alcoholics -- Family relationships Alcoholics' spouses -- South Africa Alcoholics -- South Africa -- Conduct of life
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:702 , http://hdl.handle.net/10962/d1006461
- Description: The study focused on the expenences of Xhosa-speaking couples in relationships characterized by alcohol dependency. The goal was to generate greater understanding of the descriptions of relationship issues faced by alcohol dependent respondents and their partners. Specifically, the study focused on exploring how the alcohol dependent respondents relate to their partners, their behaviour at home when drinking prior to their admission for rehabilitation, the experiences of their partners in living with alcohol dependent partners and how they coped with the situation. In order to meet this goal, literature and empirical studies were conducted. The literature study focuses on the alcohol dependent individual's behaviour, his emotions, relapse, the family's coping strategies, alcohol and marital problems and the role of the social worker as part of the rehabilitation team. During the empirical research phase, a non-probability purposive sampling procedure was adopted. Fifteen alcohol dependent clients who were admitted for treatment and rehabilitation at Thembelitsha Rehabilitation Centre (TRC) were selected. These clients were admitted to TRC during the period starting from January 1997 to June 1999 and were discharged to their homes during the research study. To collect data, interviews were conducted separately to a total of thirty respondents. Two interview schedules were used, one for the alcohol dependent respondents (Appendix A) and the other for their partners (Appendix B). This study revealed a remarkable consistency in the descriptions of relationship issues faced by alcohol dependent respondents and their partners. These are abusive behaviours by alcohol dependent respondents. The partners were reluctant and feared challenging the behaviour. The way in which partners responded to drinking and the reactions of alcohol dependent respondents are indicative of the difficult issues faced by the couples. The study also revealed that couples experience communication, financial and sexual relationship problems. The study concludes with recommendations based on the research findings
- Full Text:
- Date Issued: 2001
- Authors: Mgilane, Nomgcobo Eunice
- Date: 2001
- Subjects: Alcoholism -- South Africa Alcoholics -- Family relationships Alcoholics' spouses -- South Africa Alcoholics -- South Africa -- Conduct of life
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:702 , http://hdl.handle.net/10962/d1006461
- Description: The study focused on the expenences of Xhosa-speaking couples in relationships characterized by alcohol dependency. The goal was to generate greater understanding of the descriptions of relationship issues faced by alcohol dependent respondents and their partners. Specifically, the study focused on exploring how the alcohol dependent respondents relate to their partners, their behaviour at home when drinking prior to their admission for rehabilitation, the experiences of their partners in living with alcohol dependent partners and how they coped with the situation. In order to meet this goal, literature and empirical studies were conducted. The literature study focuses on the alcohol dependent individual's behaviour, his emotions, relapse, the family's coping strategies, alcohol and marital problems and the role of the social worker as part of the rehabilitation team. During the empirical research phase, a non-probability purposive sampling procedure was adopted. Fifteen alcohol dependent clients who were admitted for treatment and rehabilitation at Thembelitsha Rehabilitation Centre (TRC) were selected. These clients were admitted to TRC during the period starting from January 1997 to June 1999 and were discharged to their homes during the research study. To collect data, interviews were conducted separately to a total of thirty respondents. Two interview schedules were used, one for the alcohol dependent respondents (Appendix A) and the other for their partners (Appendix B). This study revealed a remarkable consistency in the descriptions of relationship issues faced by alcohol dependent respondents and their partners. These are abusive behaviours by alcohol dependent respondents. The partners were reluctant and feared challenging the behaviour. The way in which partners responded to drinking and the reactions of alcohol dependent respondents are indicative of the difficult issues faced by the couples. The study also revealed that couples experience communication, financial and sexual relationship problems. The study concludes with recommendations based on the research findings
- Full Text:
- Date Issued: 2001
The evaluation of pharmaceutical pictograms in a low-literate South African population
- Dowse, Roslind, Ehlers, Martina S
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6362 , http://hdl.handle.net/10962/d1006058
- Description: An inability to read and understand written medication instructions may be a major contributory factor to non-compliance in certain patient populations, particularly in countries with a high illiteracy rate such as South Africa. Twenty three pictograms from the USP-DI and a corresponding set of 23 locally developed, culturally sensitive pictograms for conveying medication instructions were evaluated in 46 Xhosa respondents who had attended school for a maximum of 7 years. Respondents were tested for their interpretation of all 46 pictograms at the first interview and again 3 weeks later. The correct meaning of each pictogram was explained at the end of the first interview. Preference for either the Local or USP pictograms was determined. At the follow-up interview, 20 of the Local pictograms complied with the ANSI criterion of ≥85% comprehension, compared with 11 of the USP pictograms. Respondents indicated an overwhelming preference for the Local pictograms.
- Full Text:
- Date Issued: 2001
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:6362 , http://hdl.handle.net/10962/d1006058
- Description: An inability to read and understand written medication instructions may be a major contributory factor to non-compliance in certain patient populations, particularly in countries with a high illiteracy rate such as South Africa. Twenty three pictograms from the USP-DI and a corresponding set of 23 locally developed, culturally sensitive pictograms for conveying medication instructions were evaluated in 46 Xhosa respondents who had attended school for a maximum of 7 years. Respondents were tested for their interpretation of all 46 pictograms at the first interview and again 3 weeks later. The correct meaning of each pictogram was explained at the end of the first interview. Preference for either the Local or USP pictograms was determined. At the follow-up interview, 20 of the Local pictograms complied with the ANSI criterion of ≥85% comprehension, compared with 11 of the USP pictograms. Respondents indicated an overwhelming preference for the Local pictograms.
- Full Text:
- Date Issued: 2001
The evaluation of autoxidation procedures for the selective oxidation of aliphatic alcohols
- Authors: Bacela, Siyabulela Mawande
- Date: 2001
- Subjects: Oxidation , Aliphatic compounds
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10950 , http://hdl.handle.net/10948/59 , Oxidation , Aliphatic compounds
- Description: The homogeneously catalyzed oxidation of 1-propanol by dioxygen in glacial acetic acid using cobalt(II)acetate and sodium bromide as the catalyst system has been investigated with the view of determining the significance of various experimental variables during the oxidation. The results of this investigation show unequivocally that a number of reaction variables have a direct influence upon catalytic activity and hence the reaction products. It is quite evident that the major product of this autoxidation reaction is propionic acid with the respective esters as side-products. This is an indication that the autoxidation mechanism occurs via a two-stage pathway, namely, the oxidation of 1-propanol to propionaldehyde as the primary product and, subsequently, the further oxidation of the propionaldehyde to propionic acid as the major product. Thus the esterification process of the propionic acid with the substrate 1-propanol could be termed as a side-reaction because its not facilitated by the catalyst system and it consumes the formed product. The catalyst activity has been demonstrated to depend on a number of factors, including the bromide concentration, the cobalt(II)acetate concentration, the water concentration, reaction temperature, and the presence of metal acetates as co-catalysts. There is an observed decrease in catalytic activity at high bromide concentration, which may be explained in terms of cobalt bromide complexes that form at these high concentrations. Subsequently, the same trend of catalyst activity reduction at high cobalt(II)acetate concentration may be ascribed to the “inactive” metal complexes that are susceptible to form at high metal ion concentrations. The catalytic activity increases with increase in total concentration and rapidly decreases at very high concentrations. This can be explained in terms of the observations made during the investigation of the effect of cobalt(II)acetate and bromide concentrations. The high increase in catalytic activity with increasing temperature is ascribed to the Arrhenius law, which relates the rate constant for a particular reaction to temperature. However, there is an observed loss of catalyst selectivity at high temperatures which maybe due to two possible factors. The first is simply related to an increased loss of volatile material from the reactor in the oxygen gas stream as the temperature is increased. The second relates to the increasing activity of the catalyst system for the selective decarboxylation of the carboxylic acid product. The addition of water to the reaction system rapidly reduces the catalyst activity. This detrimental effect is an indication that there is an effective competition by water with bromide for coordination sites on cobalt(II), thereby preventing the formation of the active catalyst species. The introduction of metal acetates as co-catalyst reduces the catalyst activity quite dramatically. This inhibition effect is suggested to relate to the redox potential of the respective metal ions. The results of statistical analysis of the experimentally derived response surface during the oxidation of 1-propanol, show no significant lack of fit, and the residuals obtained by applying the response surface to the design settings show that the data is normally distributed. The response surface is therefore reliable, but keeping in mind that the central composite design used is not rotatable so that its predictive power, especially outside the experimental domain investigated, is quite limited. However, several interesting observations were still possible The oxidative dehydrogenation of ethanol over supported noble-metal catalysts has been investigated with the view of identifying the most active supported noble-metal and also to compare this oxidation procedure with the autoxidation procedure. Secondly, the effect of an acidic resin as a co-catalyst was also investigated during the said oxidation. On the basis of results presented in this study during oxidative dehydrogenation of ethanol, catalysts no.2 (10% Pd/C), 8 (2% Pd/Al – Pb-promoted) and 9 (2% Pt/8% Pd/C) appear to be the most active in terms of relative rates, while catalysts 6 (10% Pd/C- Pbpromoted), 7 (5% Pd/C-shell reduced-Pb -promoted) and 10 (5% Pt 5% Pd on C) are more active based on the comparison of average rates. Two other observations are of interest. Firstly, the promotion of the Pd catalysts with lead appears to improve catalyst activity to some extent as shown by the comparisons between catalysts 1 and 5, 4 and 8, 2 and 6 and 3 and 7. Secondly, the introduction of Pt up to equal amounts with palladium seems to produce the most active catalysts. On its own, platinum appears to be a better catalyst than Pd when supported on activated carbon (catalysts 1 and 12). In comparison with the homogeneous, cobalt-bromide catalyzed oxidation of 1- propanol in the liquid-phase, oxidations over noble-metal catalysts in the liquid-phase appear to be significantly less active. The presence of the resin promoted the formation of ethyl acetate to some extent, the improvements are not as dramatic as expected.
- Full Text:
- Date Issued: 2001
- Authors: Bacela, Siyabulela Mawande
- Date: 2001
- Subjects: Oxidation , Aliphatic compounds
- Language: English
- Type: Thesis , Masters , MTech (Chemistry)
- Identifier: vital:10950 , http://hdl.handle.net/10948/59 , Oxidation , Aliphatic compounds
- Description: The homogeneously catalyzed oxidation of 1-propanol by dioxygen in glacial acetic acid using cobalt(II)acetate and sodium bromide as the catalyst system has been investigated with the view of determining the significance of various experimental variables during the oxidation. The results of this investigation show unequivocally that a number of reaction variables have a direct influence upon catalytic activity and hence the reaction products. It is quite evident that the major product of this autoxidation reaction is propionic acid with the respective esters as side-products. This is an indication that the autoxidation mechanism occurs via a two-stage pathway, namely, the oxidation of 1-propanol to propionaldehyde as the primary product and, subsequently, the further oxidation of the propionaldehyde to propionic acid as the major product. Thus the esterification process of the propionic acid with the substrate 1-propanol could be termed as a side-reaction because its not facilitated by the catalyst system and it consumes the formed product. The catalyst activity has been demonstrated to depend on a number of factors, including the bromide concentration, the cobalt(II)acetate concentration, the water concentration, reaction temperature, and the presence of metal acetates as co-catalysts. There is an observed decrease in catalytic activity at high bromide concentration, which may be explained in terms of cobalt bromide complexes that form at these high concentrations. Subsequently, the same trend of catalyst activity reduction at high cobalt(II)acetate concentration may be ascribed to the “inactive” metal complexes that are susceptible to form at high metal ion concentrations. The catalytic activity increases with increase in total concentration and rapidly decreases at very high concentrations. This can be explained in terms of the observations made during the investigation of the effect of cobalt(II)acetate and bromide concentrations. The high increase in catalytic activity with increasing temperature is ascribed to the Arrhenius law, which relates the rate constant for a particular reaction to temperature. However, there is an observed loss of catalyst selectivity at high temperatures which maybe due to two possible factors. The first is simply related to an increased loss of volatile material from the reactor in the oxygen gas stream as the temperature is increased. The second relates to the increasing activity of the catalyst system for the selective decarboxylation of the carboxylic acid product. The addition of water to the reaction system rapidly reduces the catalyst activity. This detrimental effect is an indication that there is an effective competition by water with bromide for coordination sites on cobalt(II), thereby preventing the formation of the active catalyst species. The introduction of metal acetates as co-catalyst reduces the catalyst activity quite dramatically. This inhibition effect is suggested to relate to the redox potential of the respective metal ions. The results of statistical analysis of the experimentally derived response surface during the oxidation of 1-propanol, show no significant lack of fit, and the residuals obtained by applying the response surface to the design settings show that the data is normally distributed. The response surface is therefore reliable, but keeping in mind that the central composite design used is not rotatable so that its predictive power, especially outside the experimental domain investigated, is quite limited. However, several interesting observations were still possible The oxidative dehydrogenation of ethanol over supported noble-metal catalysts has been investigated with the view of identifying the most active supported noble-metal and also to compare this oxidation procedure with the autoxidation procedure. Secondly, the effect of an acidic resin as a co-catalyst was also investigated during the said oxidation. On the basis of results presented in this study during oxidative dehydrogenation of ethanol, catalysts no.2 (10% Pd/C), 8 (2% Pd/Al – Pb-promoted) and 9 (2% Pt/8% Pd/C) appear to be the most active in terms of relative rates, while catalysts 6 (10% Pd/C- Pbpromoted), 7 (5% Pd/C-shell reduced-Pb -promoted) and 10 (5% Pt 5% Pd on C) are more active based on the comparison of average rates. Two other observations are of interest. Firstly, the promotion of the Pd catalysts with lead appears to improve catalyst activity to some extent as shown by the comparisons between catalysts 1 and 5, 4 and 8, 2 and 6 and 3 and 7. Secondly, the introduction of Pt up to equal amounts with palladium seems to produce the most active catalysts. On its own, platinum appears to be a better catalyst than Pd when supported on activated carbon (catalysts 1 and 12). In comparison with the homogeneous, cobalt-bromide catalyzed oxidation of 1- propanol in the liquid-phase, oxidations over noble-metal catalysts in the liquid-phase appear to be significantly less active. The presence of the resin promoted the formation of ethyl acetate to some extent, the improvements are not as dramatic as expected.
- Full Text:
- Date Issued: 2001
The Etendeka Igneous Province: magma types and their stratigraphic distribution with implications for the evolution of the Paraná-Etendeka flood basalt province
- Marsh, Julian S, Ewart, A, Milner, Simon C, Duncan, Andrew R, Miller, R McG
- Authors: Marsh, Julian S , Ewart, A , Milner, Simon C , Duncan, Andrew R , Miller, R McG
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149762 , vital:38882 , https://doi.org/10.1007/s004450000115
- Description: Detailed geochemical and field data for the volcanic sequence and intrusions of the Etendeka Igneous Province are used to construct a stratigraphic framework for petrogenetic interpretation of the evolution of the Etendeka-Paraná continental flood volcanic event. Geochemical and petrographic characterization of over 1,000 analyzed samples allows 8 mafic and 17 silicic magma types to be recognized.
- Full Text: false
- Date Issued: 2017
- Authors: Marsh, Julian S , Ewart, A , Milner, Simon C , Duncan, Andrew R , Miller, R McG
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149762 , vital:38882 , https://doi.org/10.1007/s004450000115
- Description: Detailed geochemical and field data for the volcanic sequence and intrusions of the Etendeka Igneous Province are used to construct a stratigraphic framework for petrogenetic interpretation of the evolution of the Etendeka-Paraná continental flood volcanic event. Geochemical and petrographic characterization of over 1,000 analyzed samples allows 8 mafic and 17 silicic magma types to be recognized.
- Full Text: false
- Date Issued: 2017
The effects of melatonin on the testis, epididymis and sperm physiology of the Wistar rat
- Authors: Gwayi, Noluzuko
- Date: 2001
- Subjects: Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5681 , http://hdl.handle.net/10962/d1005366 , Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Description: Melatonin is a product of the pineal gland and is postulated to play an antigonadotropic role in the reproductive system of mammals. The reproductive system of non-seasonally breeding mammals is believed to be not as responsive to melatonin treatment as that of seasonally breeding mammals. Recently, there has been increasing support from in vivo and in vitro studies, for the hypothesis that melatonin has negative effects on sperm physiology, especially on sperm motility. High and/or low seminal concentrations of melatonin have been associated with abnormalities in human sperm motility and concentration. In this study, I examined the effects of melatonin on the testis, epididymis and sperm physiology, using in vivo and in vitro experiments, in a non-seasonally breeding mammal. Treatment, in vivo, with exogenous melatonin for six weeks did not inhibit testosterone production or spermatogenesis, nor did it affect the mass of the testes and epididymides at dissection, the concentration the morphology of speimatozoa. However, melatonin in vivo had a small, but significant negative effect on sperm motility and sperm motility index. In vitro incubation of spermatozoa Fith melatonin reduced the percentage (%) of forward progressive movement (fpm), increased the % reduction in fpm, reduced the vigor or quality of sperm motility, reduced the sperm motility index, and delayed and/or prolonged the transition of one pattern of sperm motility to the subsequent patterns. Melatonin increased the pH of the culture medium, and the increased pH, and the ethanol utilized as a solvent for melatonin, both negatively affected all the sperm motility parameters that were assessed in my study. The effects of ethanol increased with time, and the effects of pH increased with both time and increasing pH. Melatonin in vitro did not inhibit capacitation and the acrosome reaction, but it delayed the onset and the progression of capacitation and the acrosome reaction. These results suggest that while melatonin did not inhibit spermatogenesis in the Wistar rat, it may influence sperm motility. Therefore, the presence of high concentrations of melatonin in the reproductive fluids may inhibit sperm motility. With further detailed research, melatonin may have a potential use as a contraceptive drug.
- Full Text:
- Date Issued: 2001
- Authors: Gwayi, Noluzuko
- Date: 2001
- Subjects: Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5681 , http://hdl.handle.net/10962/d1005366 , Rats as laboratory animals , Rats -- physiology , Spermatozoa , Melatonin , Testis , Epididymis
- Description: Melatonin is a product of the pineal gland and is postulated to play an antigonadotropic role in the reproductive system of mammals. The reproductive system of non-seasonally breeding mammals is believed to be not as responsive to melatonin treatment as that of seasonally breeding mammals. Recently, there has been increasing support from in vivo and in vitro studies, for the hypothesis that melatonin has negative effects on sperm physiology, especially on sperm motility. High and/or low seminal concentrations of melatonin have been associated with abnormalities in human sperm motility and concentration. In this study, I examined the effects of melatonin on the testis, epididymis and sperm physiology, using in vivo and in vitro experiments, in a non-seasonally breeding mammal. Treatment, in vivo, with exogenous melatonin for six weeks did not inhibit testosterone production or spermatogenesis, nor did it affect the mass of the testes and epididymides at dissection, the concentration the morphology of speimatozoa. However, melatonin in vivo had a small, but significant negative effect on sperm motility and sperm motility index. In vitro incubation of spermatozoa Fith melatonin reduced the percentage (%) of forward progressive movement (fpm), increased the % reduction in fpm, reduced the vigor or quality of sperm motility, reduced the sperm motility index, and delayed and/or prolonged the transition of one pattern of sperm motility to the subsequent patterns. Melatonin increased the pH of the culture medium, and the increased pH, and the ethanol utilized as a solvent for melatonin, both negatively affected all the sperm motility parameters that were assessed in my study. The effects of ethanol increased with time, and the effects of pH increased with both time and increasing pH. Melatonin in vitro did not inhibit capacitation and the acrosome reaction, but it delayed the onset and the progression of capacitation and the acrosome reaction. These results suggest that while melatonin did not inhibit spermatogenesis in the Wistar rat, it may influence sperm motility. Therefore, the presence of high concentrations of melatonin in the reproductive fluids may inhibit sperm motility. With further detailed research, melatonin may have a potential use as a contraceptive drug.
- Full Text:
- Date Issued: 2001
The effects of level and quality of education on a South African sample of English and African first language speakers, for WAIS-III digit symbol-incidental learning
- Donnelly, Martin Joseph Rhodes
- Authors: Donnelly, Martin Joseph Rhodes
- Date: 2001
- Subjects: Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2965 , http://hdl.handle.net/10962/d1002474 , Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Description: This study examined the effects of level and quality of education on WAIS-III Digit Symbol-Incidental Learning performance. The Pairing and Free Recall measures were administered to a South African sample (N = 68, age range 19-30), which was stratified for English and African language, level of education attained (Grade 12s and Graduates) and quality of education (advantaged and disadvantaged schooling). Results yielded no significant main or interaction effects between acculturation factors of level and quality of education. Normative guidelines of 13 or more pairs and 8 or more free recall symbols, appropriate to a non-clinical sample in a multicultural setting, are provided. Digit Symbol-Incidental Learning proved to be a culture-fair test, which contributes to its clinical utility as a sensitive memory screening tool.
- Full Text:
- Date Issued: 2001
- Authors: Donnelly, Martin Joseph Rhodes
- Date: 2001
- Subjects: Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2965 , http://hdl.handle.net/10962/d1002474 , Wechsler Adult Intelligence Scale , Intelligence tests -- South Africa , Wechsler Adult Intelligence Scale -- South Africa
- Description: This study examined the effects of level and quality of education on WAIS-III Digit Symbol-Incidental Learning performance. The Pairing and Free Recall measures were administered to a South African sample (N = 68, age range 19-30), which was stratified for English and African language, level of education attained (Grade 12s and Graduates) and quality of education (advantaged and disadvantaged schooling). Results yielded no significant main or interaction effects between acculturation factors of level and quality of education. Normative guidelines of 13 or more pairs and 8 or more free recall symbols, appropriate to a non-clinical sample in a multicultural setting, are provided. Digit Symbol-Incidental Learning proved to be a culture-fair test, which contributes to its clinical utility as a sensitive memory screening tool.
- Full Text:
- Date Issued: 2001
The effects of assembly line-side supply on individuals employed in satellite operations within automotive manufacturers
- Authors: Bocchi, Carlo
- Date: 2001
- Subjects: Faurecia East London (Firm) , Job satisfaction , Employee motivation , Automobile industry and trade -- Management , Automobile industry and trade -- Case studies
- Language: English
- Type: Thesis , Masters , MTech (Business Administration)
- Identifier: vital:10849 , http://hdl.handle.net/10948/56 , Faurecia East London (Firm) , Job satisfaction , Employee motivation , Automobile industry and trade -- Management , Automobile industry and trade -- Case studies
- Description: The adoption of just-in-time in satellite operations within an automotive manufacturer, is rapidly becoming a trend within motor industry clusters. This type of organisation within an organisation adopts a lean structure to operate effectively and efficiently. The objective of this paper is to unveil factors which influence this type of workplace, particularly focusing on which factors which are relevant to Faurecia East London Plant. The literature study was used to illustrate the various theories relevant to manufacturing techniques, employee motivational and job satisfaction theories. The empirical study tested factors illustrated in the literature study. The empirical study was also to develop a specific model suitable for satellite organisations. The model presented together with the literature and empirical study was used to formulate findings and solve the main and sub-problems.
- Full Text:
- Date Issued: 2001
- Authors: Bocchi, Carlo
- Date: 2001
- Subjects: Faurecia East London (Firm) , Job satisfaction , Employee motivation , Automobile industry and trade -- Management , Automobile industry and trade -- Case studies
- Language: English
- Type: Thesis , Masters , MTech (Business Administration)
- Identifier: vital:10849 , http://hdl.handle.net/10948/56 , Faurecia East London (Firm) , Job satisfaction , Employee motivation , Automobile industry and trade -- Management , Automobile industry and trade -- Case studies
- Description: The adoption of just-in-time in satellite operations within an automotive manufacturer, is rapidly becoming a trend within motor industry clusters. This type of organisation within an organisation adopts a lean structure to operate effectively and efficiently. The objective of this paper is to unveil factors which influence this type of workplace, particularly focusing on which factors which are relevant to Faurecia East London Plant. The literature study was used to illustrate the various theories relevant to manufacturing techniques, employee motivational and job satisfaction theories. The empirical study tested factors illustrated in the literature study. The empirical study was also to develop a specific model suitable for satellite organisations. The model presented together with the literature and empirical study was used to formulate findings and solve the main and sub-problems.
- Full Text:
- Date Issued: 2001
The effect of variations in pH and temperature on stability of melatonin in aqueous solution
- Daya, Santylal, Walker, Roderick B, Glass, Beverley D, Anoopkumar-Dukie, Shailendra
- Authors: Daya, Santylal , Walker, Roderick B , Glass, Beverley D , Anoopkumar-Dukie, Shailendra
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184314 , vital:44207 , xlink:href="https://doi.org/10.1034/j.1600-079x.2001.310209.x"
- Description: Melatonin (N-acetyl-5-methoxytryptamine) has a diverse range of functions, including the control of neuroendocrine events. A number of studies have shown that melatonin may be of potential benefit for the treatment of insomnia, as well as neurodegenerative disorders. At present, there are numerous dosage forms of melatonin, with the oral route of administration being most popular. Presently, there is little information on the stability of melatonin over a pH range. With the changes in pH in the gastro-intestinal tract, as well as in different experimental conditions, information on the stability of melatonin would be important. We used a high-performance liquid chromatography method to determine the stability of melatonin solutions over a pH range (1.2–12) at room temperature and at 37°C over a period of 21 days. The results show that no melatonin degradation occurred in the first 2 days. From days 3 to 21, there was a gradual decline in melatonin at all pHs, with the decline not exceeding 30%. No decline in melatonin levels occurred in the first 2 days at 37°C. From days 3 to 21, melatonin levels declined gradually, with the decline not exceeding 29%.
- Full Text:
- Date Issued: 2001
- Authors: Daya, Santylal , Walker, Roderick B , Glass, Beverley D , Anoopkumar-Dukie, Shailendra
- Date: 2001
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184314 , vital:44207 , xlink:href="https://doi.org/10.1034/j.1600-079x.2001.310209.x"
- Description: Melatonin (N-acetyl-5-methoxytryptamine) has a diverse range of functions, including the control of neuroendocrine events. A number of studies have shown that melatonin may be of potential benefit for the treatment of insomnia, as well as neurodegenerative disorders. At present, there are numerous dosage forms of melatonin, with the oral route of administration being most popular. Presently, there is little information on the stability of melatonin over a pH range. With the changes in pH in the gastro-intestinal tract, as well as in different experimental conditions, information on the stability of melatonin would be important. We used a high-performance liquid chromatography method to determine the stability of melatonin solutions over a pH range (1.2–12) at room temperature and at 37°C over a period of 21 days. The results show that no melatonin degradation occurred in the first 2 days. From days 3 to 21, there was a gradual decline in melatonin at all pHs, with the decline not exceeding 30%. No decline in melatonin levels occurred in the first 2 days at 37°C. From days 3 to 21, melatonin levels declined gradually, with the decline not exceeding 29%.
- Full Text:
- Date Issued: 2001
The effect of photoperiod on some aspects of reproduction in a Southern African rodent : the pouched mouse (Saccostomus Campestris)
- Authors: Gray, Janine
- Date: 2001
- Subjects: Mice -- Reproduction Antechinus -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5676 , http://hdl.handle.net/10962/d1005361
- Description: The pouched mouse, Saccostomus campestris is widely distributed south of the Sahara, inhabiting both subtropical and tropical latitudes and a number of different biotic zones, where it breeds seasonally. In North temperate latitudes, reproduction in small mammals is controlled by photoperiod however this cue becomes less influential as latitude decreases towards the equator. The aim of the present study is to establish the role of photoperiod in the environmental control of reproduction in a seasonally breeding small mammal at low latitudes in a highly unpredictable environment. Spermatogenesis of domesticated and Fl-generation pouched mice was not inhibited by short daylength while decreasing daylength significantly affected the oestrous cycle of adult domesticated female pouched mice. Photoperiod had little effect on the oestrous cycle of F I-generation females while a possible inherent circannual endogenous rhythm controlled inhibition of reproduction in these females. Body mass of male and female juvenile pouched mice was consistently lower in short daylength and in juvenile female pouched mice the onset of fertility may be weight-dependent. The attainment of sexual maturity of domesticated and FIlF2-generation females was retarded but not halted in short daylength and females in long daylength reached puberty 7.8 - 10.2 days earlier. Short daylength also lengthened the interval between vaginal perforation and first oestrus. Puberty in juvenile females was age-dependent as both domesticated and FIlF2-generation males attained puberty at 50 days of age, although fewer males were fertile in long daylength than short daylength. Although litter size of pouched mice was smaller in short daylength for both domesticated and wildcaught females this was not due to a reduction in the ovulation rate. Domesticated females had significantly larger litters than wild-caught females. Male and female pouched mice have evolved different reproductive strategies as males become sexually mature at the same age irrespective of photoperiod and remain fertile throughout the year. In contrast, females tend to be more complex as juveniles delay reproductive maturity and adults become nonreproductive in short daylength. However, in the presence of a fertile male and if environmental conditions are favourable, in short daylength, females can become reproductively active within approximately 3 days. Thus, although the pouched mouse has adopted a purely opportunistic reproductive strategy, vestiges of photoresponsiveness are still present in the female. The seasonality exhibited in the wild is therefore due to the female. Pouched mice live in a highly unpredictable environment so the sole use of photoperiod to regulate reproduction would be disadvantageous.
- Full Text:
- Date Issued: 2001
- Authors: Gray, Janine
- Date: 2001
- Subjects: Mice -- Reproduction Antechinus -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5676 , http://hdl.handle.net/10962/d1005361
- Description: The pouched mouse, Saccostomus campestris is widely distributed south of the Sahara, inhabiting both subtropical and tropical latitudes and a number of different biotic zones, where it breeds seasonally. In North temperate latitudes, reproduction in small mammals is controlled by photoperiod however this cue becomes less influential as latitude decreases towards the equator. The aim of the present study is to establish the role of photoperiod in the environmental control of reproduction in a seasonally breeding small mammal at low latitudes in a highly unpredictable environment. Spermatogenesis of domesticated and Fl-generation pouched mice was not inhibited by short daylength while decreasing daylength significantly affected the oestrous cycle of adult domesticated female pouched mice. Photoperiod had little effect on the oestrous cycle of F I-generation females while a possible inherent circannual endogenous rhythm controlled inhibition of reproduction in these females. Body mass of male and female juvenile pouched mice was consistently lower in short daylength and in juvenile female pouched mice the onset of fertility may be weight-dependent. The attainment of sexual maturity of domesticated and FIlF2-generation females was retarded but not halted in short daylength and females in long daylength reached puberty 7.8 - 10.2 days earlier. Short daylength also lengthened the interval between vaginal perforation and first oestrus. Puberty in juvenile females was age-dependent as both domesticated and FIlF2-generation males attained puberty at 50 days of age, although fewer males were fertile in long daylength than short daylength. Although litter size of pouched mice was smaller in short daylength for both domesticated and wildcaught females this was not due to a reduction in the ovulation rate. Domesticated females had significantly larger litters than wild-caught females. Male and female pouched mice have evolved different reproductive strategies as males become sexually mature at the same age irrespective of photoperiod and remain fertile throughout the year. In contrast, females tend to be more complex as juveniles delay reproductive maturity and adults become nonreproductive in short daylength. However, in the presence of a fertile male and if environmental conditions are favourable, in short daylength, females can become reproductively active within approximately 3 days. Thus, although the pouched mouse has adopted a purely opportunistic reproductive strategy, vestiges of photoresponsiveness are still present in the female. The seasonality exhibited in the wild is therefore due to the female. Pouched mice live in a highly unpredictable environment so the sole use of photoperiod to regulate reproduction would be disadvantageous.
- Full Text:
- Date Issued: 2001
The effect of increased propolis production on the productivity of a honeybee farming system
- Authors: De Jager, Andries Johannes
- Date: 2001
- Subjects: Propolis
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10952 , http://hdl.handle.net/10948/d1001743 , Propolis
- Description: This study was conducted to investigate a method for stimulating increased propolis production in Cape honeybee hives. The study took place near George situated in the Southern Cape region of South Africa. Standard Langstroth hives were used (n = 12) containing honeybee colonies of equal strength from the species Apis mellifera capensis. Propolis production in colonies equipped with commercial propolis traps (n = 6) was compared to propolis production in control colonies (n = 6). The strength of the colonies was determined by calculating the area of worker brood cells and the number of frames containing bees. For a ninemonth period propolis production, honey production, brood area, resin percentage, frames containing bees and income generated were measured on a monthly basis with the removal of the traps. There were no significant difference (p > 0.5) in honey production (24.66 ± 1.19 kg and 26.53 ± 1.31 kg), worker brood area (1967.3 ± 258.61 cm2 and 1085.4 ± 312.99 cm2) and frames containing bees (10 ± 1.13 frames and 9.8 ± 1.2 frames) between the hives with traps and hives without traps. However, propolis production was significantly influenced (p < 0.01) by the propolis traps, with the hives containing traps producing 361.87 ± 8.78g propolis compared to 38.2 ± 2.17g propolis in the control group. Propolis production in both control (28 g) and treatment groups (260.2 g) was significantly influenced by honey flow (p = 0.027). From December to March the production of honey was 22.12 (control) and 24.25 kg (treatment). A positive correlation was also found between frames containing bees and worker brood area (R = 0.73). Hives containing propolis traps were more profitable than the control group when honey and propolis income were pooled (467.17 ± 19.47 Rand vs. 353.8 ± 17.03 Rand). Therefore, the increased propolis production significantly improved profitability of the hive without affecting overall hive productivity.
- Full Text:
- Date Issued: 2001
- Authors: De Jager, Andries Johannes
- Date: 2001
- Subjects: Propolis
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10952 , http://hdl.handle.net/10948/d1001743 , Propolis
- Description: This study was conducted to investigate a method for stimulating increased propolis production in Cape honeybee hives. The study took place near George situated in the Southern Cape region of South Africa. Standard Langstroth hives were used (n = 12) containing honeybee colonies of equal strength from the species Apis mellifera capensis. Propolis production in colonies equipped with commercial propolis traps (n = 6) was compared to propolis production in control colonies (n = 6). The strength of the colonies was determined by calculating the area of worker brood cells and the number of frames containing bees. For a ninemonth period propolis production, honey production, brood area, resin percentage, frames containing bees and income generated were measured on a monthly basis with the removal of the traps. There were no significant difference (p > 0.5) in honey production (24.66 ± 1.19 kg and 26.53 ± 1.31 kg), worker brood area (1967.3 ± 258.61 cm2 and 1085.4 ± 312.99 cm2) and frames containing bees (10 ± 1.13 frames and 9.8 ± 1.2 frames) between the hives with traps and hives without traps. However, propolis production was significantly influenced (p < 0.01) by the propolis traps, with the hives containing traps producing 361.87 ± 8.78g propolis compared to 38.2 ± 2.17g propolis in the control group. Propolis production in both control (28 g) and treatment groups (260.2 g) was significantly influenced by honey flow (p = 0.027). From December to March the production of honey was 22.12 (control) and 24.25 kg (treatment). A positive correlation was also found between frames containing bees and worker brood area (R = 0.73). Hives containing propolis traps were more profitable than the control group when honey and propolis income were pooled (467.17 ± 19.47 Rand vs. 353.8 ± 17.03 Rand). Therefore, the increased propolis production significantly improved profitability of the hive without affecting overall hive productivity.
- Full Text:
- Date Issued: 2001
The ecology and physiology of the springhare (Pedetes capensis) in the Eastern Cape Province of South Africa
- Authors: Peinke, Dean Michael
- Date: 2001
- Subjects: Hares -- South Africa -- Eastern Cape Hares -- Breeding -- South Africa -- Eastern Cape Hares -- Ecology -- South Africa -- Eastern Cape Hares -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5670 , http://hdl.handle.net/10962/d1005355
- Description: Springhare are large, bipedal, nocturnal, herbivorous, burrowing rodents that are found in arid and semi-arid parts of southern and eastern Africa. In this thesis I examine the general ecology, biology and physiology of these animals in the Eastern Cape Province of South Africa. An investigation of their distribution and activity in the study site showed that springhare exhibit a preference for flat, open, recently disturbed habitat that is dominated by the grass Cynodon dactylon and the sedge Cyperus esculentus. These two species constitute a major proportion of their diet. The impact of spring hare on chicory and grazing is also discussed. Nightly activity generally peaks soon after dark and decreases in the 2-4 hour period before sunrise. This pattern is, however, modified by moonlight. Springhare typically respond to moonlight by reducing aboveground activity, shifting their activity to dark moonless periods of the night, and by reducing their use of open space. Contrary to earlier reports, springhare utilise several different burrow systems spread over large areas. They regularly change burrow systems and seldom spend more than a few consecutive days in each. Springhare do not appear to defend territories but recently used burrows appear to be avoided by conspecifics. Males and females on average use a similar number of burrows, scattered over similar sized areas. Burrows are shown to provide a stable microclimate of moderate temperature and high humidity throughout the year. Reproduction is continuous and there is no synchronised breeding season. The ability to reproduce throughout the year is attributed primarily to their ability to utilise subterranean food stores. The overall reproductive strategy of springhare (a single young with long gestation and weaning) is unusual for a mammal of this size but may be linked to low levels of adult and juvenile mortality. Physiologically, springhare are reasonably well adapted to life in hot, arid environments. They produce a concentrated urine, exhibit a high tolerance to dehydration, are good osmoregulators capable of maintaining plasma volume, osmolality and ion balance over long periods of water deprivation, and are able to produce dry faeces. They are also good thermoregulators at low ambient temperatures, which are usually encountered at night, but are poor thermoregulators at high ambient temperatures, which they avoid behaviourally.
- Full Text:
- Date Issued: 2001
- Authors: Peinke, Dean Michael
- Date: 2001
- Subjects: Hares -- South Africa -- Eastern Cape Hares -- Breeding -- South Africa -- Eastern Cape Hares -- Ecology -- South Africa -- Eastern Cape Hares -- Physiology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5670 , http://hdl.handle.net/10962/d1005355
- Description: Springhare are large, bipedal, nocturnal, herbivorous, burrowing rodents that are found in arid and semi-arid parts of southern and eastern Africa. In this thesis I examine the general ecology, biology and physiology of these animals in the Eastern Cape Province of South Africa. An investigation of their distribution and activity in the study site showed that springhare exhibit a preference for flat, open, recently disturbed habitat that is dominated by the grass Cynodon dactylon and the sedge Cyperus esculentus. These two species constitute a major proportion of their diet. The impact of spring hare on chicory and grazing is also discussed. Nightly activity generally peaks soon after dark and decreases in the 2-4 hour period before sunrise. This pattern is, however, modified by moonlight. Springhare typically respond to moonlight by reducing aboveground activity, shifting their activity to dark moonless periods of the night, and by reducing their use of open space. Contrary to earlier reports, springhare utilise several different burrow systems spread over large areas. They regularly change burrow systems and seldom spend more than a few consecutive days in each. Springhare do not appear to defend territories but recently used burrows appear to be avoided by conspecifics. Males and females on average use a similar number of burrows, scattered over similar sized areas. Burrows are shown to provide a stable microclimate of moderate temperature and high humidity throughout the year. Reproduction is continuous and there is no synchronised breeding season. The ability to reproduce throughout the year is attributed primarily to their ability to utilise subterranean food stores. The overall reproductive strategy of springhare (a single young with long gestation and weaning) is unusual for a mammal of this size but may be linked to low levels of adult and juvenile mortality. Physiologically, springhare are reasonably well adapted to life in hot, arid environments. They produce a concentrated urine, exhibit a high tolerance to dehydration, are good osmoregulators capable of maintaining plasma volume, osmolality and ion balance over long periods of water deprivation, and are able to produce dry faeces. They are also good thermoregulators at low ambient temperatures, which are usually encountered at night, but are poor thermoregulators at high ambient temperatures, which they avoid behaviourally.
- Full Text:
- Date Issued: 2001
The distinction between a contract of employment and a contract with an independent contractor
- Authors: Slater, Henry John
- Date: 2001
- Subjects: Labor contract -- South Africa , Independent contractors -- South Africa , Contracts -- South Africa -- Cases , Liability (Law) -- South Africa , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11060 , http://hdl.handle.net/10948/276 , Labor contract -- South Africa , Independent contractors -- South Africa , Contracts -- South Africa -- Cases , Liability (Law) -- South Africa , Labor laws and legislation -- South Africa
- Description: The purpose of this treatise was to determine the distinction between the contract of service (employment) and the contract of work (independent contractor). A comprehensive literary survey was undertaken so as to establish if such a distinction does indeed exist. A logical point of departure was to study the contract of service and determine how the employment relationship is established by it. It is also necessary to establish under what circumstances a contract may be terminated and what the rights and obligations of the parties to the contract were. The contract between the parties will determine remedies to the breach of contract or applicability of labour legislation. It is also necessary to establish the definition of an employee under various statutes so as to understand what remedies exist should rights be infringed upon. Statutes considered include the Constitution of the Republic of South Africa, Labour Relations Act, Basic Conditions of Employment Act, Employment Equity Act, Unemployment Insurance Act, Compensation for Occupational Injuries and Diseases Act, Skills Development Act and the Income Tax Act. The effect of insolvency of the employer on the employee is also discussed. Outsourcing has played a major role in the emergence of the independent contractor. This phenomenon is considered from the point of the employer in terms of the reasons for choosing the option of outsourcing and the associated risks. The employee perspective is also dealt with in terms of why an employee would change his/her employment status. The various tests historically applied to determine the status of a worker is also discussed. These include the control, organisation, dominant impression and economic tests. Currently the dominant impression test is the one that is being applied to determine the employment relationship. Extensive reference was made to case law. United States of America cases are referred to with specific reference to the 20 Factor Test applied by the Internal Revenue Service. South African case law is dealt wit in terms of enforcement of Bargaining Council agreements, commission-earning persons, payment for services rendered, the intention of the parties and the identity of the true employer. The emergence of the dependent contractor is also addressed. This form of worker normally falls outside of the protection of labour legislation and social security. Amendments have been proposed to various statutes to remedy the situation in South Africa. A final aspect that is dealt with is that of vicarious liability. The applicability of this aspect lies in the liability of the employer for damages inflicted by the employee.
- Full Text:
- Date Issued: 2001
- Authors: Slater, Henry John
- Date: 2001
- Subjects: Labor contract -- South Africa , Independent contractors -- South Africa , Contracts -- South Africa -- Cases , Liability (Law) -- South Africa , Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:11060 , http://hdl.handle.net/10948/276 , Labor contract -- South Africa , Independent contractors -- South Africa , Contracts -- South Africa -- Cases , Liability (Law) -- South Africa , Labor laws and legislation -- South Africa
- Description: The purpose of this treatise was to determine the distinction between the contract of service (employment) and the contract of work (independent contractor). A comprehensive literary survey was undertaken so as to establish if such a distinction does indeed exist. A logical point of departure was to study the contract of service and determine how the employment relationship is established by it. It is also necessary to establish under what circumstances a contract may be terminated and what the rights and obligations of the parties to the contract were. The contract between the parties will determine remedies to the breach of contract or applicability of labour legislation. It is also necessary to establish the definition of an employee under various statutes so as to understand what remedies exist should rights be infringed upon. Statutes considered include the Constitution of the Republic of South Africa, Labour Relations Act, Basic Conditions of Employment Act, Employment Equity Act, Unemployment Insurance Act, Compensation for Occupational Injuries and Diseases Act, Skills Development Act and the Income Tax Act. The effect of insolvency of the employer on the employee is also discussed. Outsourcing has played a major role in the emergence of the independent contractor. This phenomenon is considered from the point of the employer in terms of the reasons for choosing the option of outsourcing and the associated risks. The employee perspective is also dealt with in terms of why an employee would change his/her employment status. The various tests historically applied to determine the status of a worker is also discussed. These include the control, organisation, dominant impression and economic tests. Currently the dominant impression test is the one that is being applied to determine the employment relationship. Extensive reference was made to case law. United States of America cases are referred to with specific reference to the 20 Factor Test applied by the Internal Revenue Service. South African case law is dealt wit in terms of enforcement of Bargaining Council agreements, commission-earning persons, payment for services rendered, the intention of the parties and the identity of the true employer. The emergence of the dependent contractor is also addressed. This form of worker normally falls outside of the protection of labour legislation and social security. Amendments have been proposed to various statutes to remedy the situation in South Africa. A final aspect that is dealt with is that of vicarious liability. The applicability of this aspect lies in the liability of the employer for damages inflicted by the employee.
- Full Text:
- Date Issued: 2001
The development of the common fraction concept in grade three learners
- Authors: Fraser, Claire Anne
- Date: 2001
- Subjects: Mathematics -- Study and teaching (Elementary) Mathematics Problems, exercises, etc Fractions -- Study and teaching (Elementary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1497 , http://hdl.handle.net/10962/d1003379
- Description: Over a period of nine months in 1999, a longitudinal teaching intervention was undertaken with Grade 3 learners in the Fort Beaufort district, Eastern Cape. Working in the interpretive paradigm, the intervention focussed on: - the development of the common fraction concept, - the relevance of the hierarchy of Murray and Olivier’s Four Levels of Development in common fractions and - whether learners’ informal knowledge could be utilised in developing this concept. Using the Problem-centred approach to teaching mathematics, problems set in reallife contexts were used as vehicles for learning. Learners were required to discuss, reflect and make sense of the mathematics they were doing. Participant observation, completed worksheets and unstructured interviews with learners, formed the primary method of data collection. Learners’ work was analysed and classified according to the method used and manner in which the solution was notated. Results showed that learners were able to achieve a significant degree of success in developing a stable common fraction concept. Learners were afforded opportunities to construct their own ideas and to develop a deeper understanding of the concept. Many methods used were based on their informal knowledge of sharing. Learners made sense of realistic problems using drawings, and invented their own procedures. Apart from Level One, Phase Three, all Murray and Olivier’s Levels of Development could be identified during the research. This study will provide educators with valuable information on how learners solve mathematical problems involving fractions and how informal knowledge can be used as a foundation on which to build.
- Full Text:
- Date Issued: 2001
- Authors: Fraser, Claire Anne
- Date: 2001
- Subjects: Mathematics -- Study and teaching (Elementary) Mathematics Problems, exercises, etc Fractions -- Study and teaching (Elementary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1497 , http://hdl.handle.net/10962/d1003379
- Description: Over a period of nine months in 1999, a longitudinal teaching intervention was undertaken with Grade 3 learners in the Fort Beaufort district, Eastern Cape. Working in the interpretive paradigm, the intervention focussed on: - the development of the common fraction concept, - the relevance of the hierarchy of Murray and Olivier’s Four Levels of Development in common fractions and - whether learners’ informal knowledge could be utilised in developing this concept. Using the Problem-centred approach to teaching mathematics, problems set in reallife contexts were used as vehicles for learning. Learners were required to discuss, reflect and make sense of the mathematics they were doing. Participant observation, completed worksheets and unstructured interviews with learners, formed the primary method of data collection. Learners’ work was analysed and classified according to the method used and manner in which the solution was notated. Results showed that learners were able to achieve a significant degree of success in developing a stable common fraction concept. Learners were afforded opportunities to construct their own ideas and to develop a deeper understanding of the concept. Many methods used were based on their informal knowledge of sharing. Learners made sense of realistic problems using drawings, and invented their own procedures. Apart from Level One, Phase Three, all Murray and Olivier’s Levels of Development could be identified during the research. This study will provide educators with valuable information on how learners solve mathematical problems involving fractions and how informal knowledge can be used as a foundation on which to build.
- Full Text:
- Date Issued: 2001
The development of a technique to establish the security requirements of an organization
- Authors: Gerber, Mariana
- Date: 2001
- Subjects: Computer security -- Management , Electronic data processing departments -- Security measures , Businesses -- Data processing -- Security measures , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MTech (Information Technology)
- Identifier: vital:10789 , http://hdl.handle.net/10948/89 , Computer security -- Management , Electronic data processing departments -- Security measures , Businesses -- Data processing -- Security measures , Computers -- Access control
- Description: To perform their business activities effectively, organizations rely heavily on the use of information (ISO/IEC TR 13335-2, 1996, p 1). Owens (1998) reiterates this by claiming that all organizations depend on information for their everyday operation and without it business will fail to operate (Owens, 1998, p 1-2). For an organization it means that if the right information is not available at the right time, it can make the difference between profit and loss or success and failure (Royds, 2000, p 2). Information is an asset and just like other important business assets within the organization, it has extreme value to an organization (BS 7799-1, 1999, p 1; Humphreys, Moses & Plate, 1998, p 8). For this reason it has become very important that business information is sufficiently protected. There are many different ways in which information can exist. Information can be printed or written on paper, stored electronically, transmitted electronically or by post, even spoken in conversation or any other way in which knowledge and ideas can be conveyed (URN 99/703, 1999, p. 2; Humphreys, Moses & Plate, 1998, p 8; URN 96/702, 1996, p 3).It is, therefore, critical to protect information, and to ensure that the security of IT (Information Technology) systems within organizations is properly managed. This requirement to protect information is even more important today, since many organizations are internally and externally connected by networks of IT systems (ISO/IEC TR 13335-2, 1996, p 1). Information security is therefore required to assist in the process of controlling and securing of information from accidental or malicious changes, deletions or unauthorized disclosure (Royds, 2000, p 2; URN 96/702, 1996, p 3). By preventing and minimizing the impact of security incidents, information security can ensure business continuity and reduce business damage (Owens, 1998, p 7). Information security in an organization can be regarded as a management opportunity and should become an integral part of the whole management activity of the organization. Obtaining commitment from management is therefore extremely important for effective information security. One way in which management can show their commitment to ensuring information security, is to adopt and enforce a security policy. A security policy ensures that people understand exactly what important role they play in securing information assets.
- Full Text:
- Date Issued: 2001
- Authors: Gerber, Mariana
- Date: 2001
- Subjects: Computer security -- Management , Electronic data processing departments -- Security measures , Businesses -- Data processing -- Security measures , Computers -- Access control
- Language: English
- Type: Thesis , Masters , MTech (Information Technology)
- Identifier: vital:10789 , http://hdl.handle.net/10948/89 , Computer security -- Management , Electronic data processing departments -- Security measures , Businesses -- Data processing -- Security measures , Computers -- Access control
- Description: To perform their business activities effectively, organizations rely heavily on the use of information (ISO/IEC TR 13335-2, 1996, p 1). Owens (1998) reiterates this by claiming that all organizations depend on information for their everyday operation and without it business will fail to operate (Owens, 1998, p 1-2). For an organization it means that if the right information is not available at the right time, it can make the difference between profit and loss or success and failure (Royds, 2000, p 2). Information is an asset and just like other important business assets within the organization, it has extreme value to an organization (BS 7799-1, 1999, p 1; Humphreys, Moses & Plate, 1998, p 8). For this reason it has become very important that business information is sufficiently protected. There are many different ways in which information can exist. Information can be printed or written on paper, stored electronically, transmitted electronically or by post, even spoken in conversation or any other way in which knowledge and ideas can be conveyed (URN 99/703, 1999, p. 2; Humphreys, Moses & Plate, 1998, p 8; URN 96/702, 1996, p 3).It is, therefore, critical to protect information, and to ensure that the security of IT (Information Technology) systems within organizations is properly managed. This requirement to protect information is even more important today, since many organizations are internally and externally connected by networks of IT systems (ISO/IEC TR 13335-2, 1996, p 1). Information security is therefore required to assist in the process of controlling and securing of information from accidental or malicious changes, deletions or unauthorized disclosure (Royds, 2000, p 2; URN 96/702, 1996, p 3). By preventing and minimizing the impact of security incidents, information security can ensure business continuity and reduce business damage (Owens, 1998, p 7). Information security in an organization can be regarded as a management opportunity and should become an integral part of the whole management activity of the organization. Obtaining commitment from management is therefore extremely important for effective information security. One way in which management can show their commitment to ensuring information security, is to adopt and enforce a security policy. A security policy ensures that people understand exactly what important role they play in securing information assets.
- Full Text:
- Date Issued: 2001
The development of a scale to measure sexual orientation and an examination of its psychometric properties
- Authors: Heath, Lance Julien
- Date: 2001
- Subjects: Sexual orientation , Sexual orientation -- Research -- Psychological aspects , Psychometrics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3145 , http://hdl.handle.net/10962/d1007408 , Sexual orientation , Sexual orientation -- Research -- Psychological aspects , Psychometrics
- Description: The purpose of the study was to develop a scale to measure sexual orientation and to examine its psychometric properties. Previous scales were critically examined and compared and the need for a scale which simultaneously measures same and opposite sex responsiveness independently, and accounts for dynamic changes over time, while testing a number of overt and covert dimensions of sexual orientations, was established. A 48-item scale was designed to tap self-reported intensity and frequency of Emotional Attachment, Sexual Fantasy, Sexual Attraction and Sexual Contact towards males and females in the Past, Present and Future. An initial study was conducted with 13 undergraduate university students of both genders, representing a variety of sexual orientations and nationalities, and qualitative feedback was obtained and utilized to make appropriate adjustments and refinements to the scale. The scale was then administered to 133 Rhodes University undergraduate psychology students to obtain quantitative data with regard to its internal structure. The scale was found to have a good internal consistency reliability Cronbach alpha coefficient of 0.8106. Existing sub-scales had lower alpha coefficients. Factor analysis, a form of construct validation, was performed and four factors emerged. These had very good internal consistency reliability alpha coefficients: Sexual Responsiveness to Females (0.9894), Sexual Responsiveness to Males (0.9741), Emotional Attachment to Females (0.8403) and Emotional Attachment to Males (0.8372). These factors were further statistically analysed to ascertain how they relate to one another and to the demographics of gender, age, relational status and sexual orientation identity. Future research will need to assess other forms of reliability and validity and focus on larger and more varied samples.
- Full Text:
- Date Issued: 2001
- Authors: Heath, Lance Julien
- Date: 2001
- Subjects: Sexual orientation , Sexual orientation -- Research -- Psychological aspects , Psychometrics
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3145 , http://hdl.handle.net/10962/d1007408 , Sexual orientation , Sexual orientation -- Research -- Psychological aspects , Psychometrics
- Description: The purpose of the study was to develop a scale to measure sexual orientation and to examine its psychometric properties. Previous scales were critically examined and compared and the need for a scale which simultaneously measures same and opposite sex responsiveness independently, and accounts for dynamic changes over time, while testing a number of overt and covert dimensions of sexual orientations, was established. A 48-item scale was designed to tap self-reported intensity and frequency of Emotional Attachment, Sexual Fantasy, Sexual Attraction and Sexual Contact towards males and females in the Past, Present and Future. An initial study was conducted with 13 undergraduate university students of both genders, representing a variety of sexual orientations and nationalities, and qualitative feedback was obtained and utilized to make appropriate adjustments and refinements to the scale. The scale was then administered to 133 Rhodes University undergraduate psychology students to obtain quantitative data with regard to its internal structure. The scale was found to have a good internal consistency reliability Cronbach alpha coefficient of 0.8106. Existing sub-scales had lower alpha coefficients. Factor analysis, a form of construct validation, was performed and four factors emerged. These had very good internal consistency reliability alpha coefficients: Sexual Responsiveness to Females (0.9894), Sexual Responsiveness to Males (0.9741), Emotional Attachment to Females (0.8403) and Emotional Attachment to Males (0.8372). These factors were further statistically analysed to ascertain how they relate to one another and to the demographics of gender, age, relational status and sexual orientation identity. Future research will need to assess other forms of reliability and validity and focus on larger and more varied samples.
- Full Text:
- Date Issued: 2001