Myth, Music & Modernism: the Wagnerian dimension in Virginia Woolf's Mrs Dalloway and the waves and James Joyce’s Finnegans Wake
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
National identity and nation-building in post-apartheid South Africa
- Authors: Stinson, Andrew Todd
- Date: 2009
- Subjects: Post-apartheid era -- South Africa , South Africa -- Politics and government -- 1994- , Nationalism -- South Africa , Civil society -- South Africa , Democracy -- South Africa , South Africa -- Social policy , Ethnicity -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2832 , http://hdl.handle.net/10962/d1003042
- Description: Throughout South Africa’s post-Apartheid history, the ANC-led government has undertaken a distinct nation-building program in pursuit of “a truly united, democratic and prosperous South Africa” (ANC, 2007). This is reflected in a two-pronged approach, coupling political and socioeconomic transformation with the social-psychological aspect of forging a broad and inclusive national consciousness. The ANC’s “rainbow nation” approach embraces cultural diversity through what I shall call the practice of “interculturalism”. Interculturalism is a way of recognizing commonalities, reducing tensions and promoting the formation of social partnerships among different cultural groups. The ANC has also promoted a civic culture based on the principles of liberal democracy, non-racism, equality and the protection of individual rights. Interculturalism and civic nationalism are critically important factors to South African nation-building since together they foster a shared public culture and support meaningful participation in the creation of a truly just and democratic South Africa. Unfortunately, in many ways South African society remains deeply divided by race, ethnicity and economic inequality. This thesis analyses various theoretical approaches to national identity and nationbuilding with the aim of identifying several concepts which arguably throw light on the problems of South African nation-building and national identity formation. It is argued that interculturalism and civic nationalism are context appropriate approaches which have been adopted by the ANC to further an inclusive sense of shared public culture and promote participation in the creation of a shared public future. These approaches have led to the limited emergence of a broad South African national identity. However, South Africa’s commitment to socio-economic transformation has been less successful in generating widespread support for a broad national identity. While some of those previously disadvantaged under Apartheid have benefited from poverty alleviation schemes, service delivery initiatives and black economic empowerment programs, many continue to suffer from homelessness, unemployment and worsening economic conditions. Increasing economic marginalization has caused growing discontent among South Africa’s poor and constitutes the biggest threat to the formation of a cohesive national identity in South African society. Ultimately, it is argued that while interculturalism and civic nationalism have played an important role in fostering the growth of a broad national identity, true South African social cohesion will fail to emerge without a massive and sustained commitment to wide-ranging socio-economic transformation.
- Full Text:
- Date Issued: 2009
- Authors: Stinson, Andrew Todd
- Date: 2009
- Subjects: Post-apartheid era -- South Africa , South Africa -- Politics and government -- 1994- , Nationalism -- South Africa , Civil society -- South Africa , Democracy -- South Africa , South Africa -- Social policy , Ethnicity -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2832 , http://hdl.handle.net/10962/d1003042
- Description: Throughout South Africa’s post-Apartheid history, the ANC-led government has undertaken a distinct nation-building program in pursuit of “a truly united, democratic and prosperous South Africa” (ANC, 2007). This is reflected in a two-pronged approach, coupling political and socioeconomic transformation with the social-psychological aspect of forging a broad and inclusive national consciousness. The ANC’s “rainbow nation” approach embraces cultural diversity through what I shall call the practice of “interculturalism”. Interculturalism is a way of recognizing commonalities, reducing tensions and promoting the formation of social partnerships among different cultural groups. The ANC has also promoted a civic culture based on the principles of liberal democracy, non-racism, equality and the protection of individual rights. Interculturalism and civic nationalism are critically important factors to South African nation-building since together they foster a shared public culture and support meaningful participation in the creation of a truly just and democratic South Africa. Unfortunately, in many ways South African society remains deeply divided by race, ethnicity and economic inequality. This thesis analyses various theoretical approaches to national identity and nationbuilding with the aim of identifying several concepts which arguably throw light on the problems of South African nation-building and national identity formation. It is argued that interculturalism and civic nationalism are context appropriate approaches which have been adopted by the ANC to further an inclusive sense of shared public culture and promote participation in the creation of a shared public future. These approaches have led to the limited emergence of a broad South African national identity. However, South Africa’s commitment to socio-economic transformation has been less successful in generating widespread support for a broad national identity. While some of those previously disadvantaged under Apartheid have benefited from poverty alleviation schemes, service delivery initiatives and black economic empowerment programs, many continue to suffer from homelessness, unemployment and worsening economic conditions. Increasing economic marginalization has caused growing discontent among South Africa’s poor and constitutes the biggest threat to the formation of a cohesive national identity in South African society. Ultimately, it is argued that while interculturalism and civic nationalism have played an important role in fostering the growth of a broad national identity, true South African social cohesion will fail to emerge without a massive and sustained commitment to wide-ranging socio-economic transformation.
- Full Text:
- Date Issued: 2009
New platinum coordination compounds : their synthesis, characterization and anticancer application
- Authors: Oosthuizen, Lukas Marthinus
- Date: 2009
- Subjects: Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10430 , http://hdl.handle.net/10948/d1018795
- Description: The aim of this thesis was to investigate the properties of novel platinum compounds with possible potential as anticancer agents, and to determine how their behaviour could lead to a better understanding of the chemistry involved. The final criteria were improvement of their anticancer behaviour. Since many questions are still unanswered as to the role of sulfur in anticancer action, studies were undertaken to synthesize novel platinum(II) complexes having non-leaving groups consisting of a combination of an aromatic nitrogen and thioetherial sulfur capable of forming a five membered ring upon coordination. The structural unit was 1-methyl-2-methylthioalkyl/aryl. Numerous complexes formed by these ligands each having chloro, bromo, iodo and oxalato leaving groups were then fully characterized. The results obtained by the various synthetic methods were compared and explained in terms of the chemistry involved. The role of the sulfur donor was indicated in both the halo- and oxalato-complexes and proved to be strongly influenced by the nature of the leaving groups. Their differences are reflected in their anticancer behaviour. The study was extended to mononitroplatinum(IV) complexes, in view of the kinetically stable platinum(IV) compounds and advantages related to this. A specific mononitroplatinum(IV) complex which proved to have good anticancer and STAT 3 properties could according to the literature not be synthesized successfully in a good yield and a high degree of purity. The results of extensive studies showed that the main problem centred around the simultaneous reactions in equilibrium during the synthesis. A number of these species formed as a result of side reactions could be identified and their close separation factors indicated chromatographically. The mechanism of these reactions and the unstable intermediate species involved could be rationalized and compared to analogues in the literature. All the complexes studied were characterized by spectral and thermal methods both in solution as well as the solid state. Their anticancer behaviour towards three anticancer cell lines (Hela, MCF 7, Ht 29) were determined and acted as a guide towards possible structural modifications for their improved capability. Three crystal structures of platinum(II) complexes were determined. The extent of the ionization of the platinum(II) complexes as well the redox potentials (Pt(II) / Pt(IV)) of the platinum(IV) complexes were particularly important factors pertaining to their anticancer action.
- Full Text:
- Date Issued: 2009
- Authors: Oosthuizen, Lukas Marthinus
- Date: 2009
- Subjects: Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10430 , http://hdl.handle.net/10948/d1018795
- Description: The aim of this thesis was to investigate the properties of novel platinum compounds with possible potential as anticancer agents, and to determine how their behaviour could lead to a better understanding of the chemistry involved. The final criteria were improvement of their anticancer behaviour. Since many questions are still unanswered as to the role of sulfur in anticancer action, studies were undertaken to synthesize novel platinum(II) complexes having non-leaving groups consisting of a combination of an aromatic nitrogen and thioetherial sulfur capable of forming a five membered ring upon coordination. The structural unit was 1-methyl-2-methylthioalkyl/aryl. Numerous complexes formed by these ligands each having chloro, bromo, iodo and oxalato leaving groups were then fully characterized. The results obtained by the various synthetic methods were compared and explained in terms of the chemistry involved. The role of the sulfur donor was indicated in both the halo- and oxalato-complexes and proved to be strongly influenced by the nature of the leaving groups. Their differences are reflected in their anticancer behaviour. The study was extended to mononitroplatinum(IV) complexes, in view of the kinetically stable platinum(IV) compounds and advantages related to this. A specific mononitroplatinum(IV) complex which proved to have good anticancer and STAT 3 properties could according to the literature not be synthesized successfully in a good yield and a high degree of purity. The results of extensive studies showed that the main problem centred around the simultaneous reactions in equilibrium during the synthesis. A number of these species formed as a result of side reactions could be identified and their close separation factors indicated chromatographically. The mechanism of these reactions and the unstable intermediate species involved could be rationalized and compared to analogues in the literature. All the complexes studied were characterized by spectral and thermal methods both in solution as well as the solid state. Their anticancer behaviour towards three anticancer cell lines (Hela, MCF 7, Ht 29) were determined and acted as a guide towards possible structural modifications for their improved capability. Three crystal structures of platinum(II) complexes were determined. The extent of the ionization of the platinum(II) complexes as well the redox potentials (Pt(II) / Pt(IV)) of the platinum(IV) complexes were particularly important factors pertaining to their anticancer action.
- Full Text:
- Date Issued: 2009
Normative indicators for a black, Xhosa speaking population without tertiary education on four tests used to access malingering
- Authors: Wong, Andrea Jane
- Date: 2009
- Subjects: Malingering Neuropsychological tests Language and languages -- Ability testing Educational tests and measurements Education evaluation Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3088 , http://hdl.handle.net/10962/d1002597
- Description: Malingering has become an increasing concern in neuropsychological assessment in recent years, and a wide range of tests have been designed and examined for the purpose of detecting malingering. Cut-off scores have been recommended for these tests in order to provide indications of malingering performances. However, the derived scores have been in respect of westernised populations of people with relatively high levels of education who speak English as their first language. Accordingly, the current study aimed to attain normative data and cut-off scores for four commonly employed neuropsychological tools, administered in English, on a population of black, South African, Xhosa-speaking people (N = 33), who attended a former DET-type school in the Eastern Cape, with a Grade 11-12 level of education, in the age range of 18 - 40 years. The targeted measures included the TOMM, the Rey-15 Item Memory Test, the Digit Span subtest of the WAIS-III, and the Trail Making Test. The obtained scores were poorer than the previously published cut-offs for at least one component of each of the tests investigated, except the TOMM. The fmdings of this study highlight the important role that the factors of culture, quality of education, and language play in neuropsychological test performance.
- Full Text:
- Date Issued: 2009
- Authors: Wong, Andrea Jane
- Date: 2009
- Subjects: Malingering Neuropsychological tests Language and languages -- Ability testing Educational tests and measurements Education evaluation Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3088 , http://hdl.handle.net/10962/d1002597
- Description: Malingering has become an increasing concern in neuropsychological assessment in recent years, and a wide range of tests have been designed and examined for the purpose of detecting malingering. Cut-off scores have been recommended for these tests in order to provide indications of malingering performances. However, the derived scores have been in respect of westernised populations of people with relatively high levels of education who speak English as their first language. Accordingly, the current study aimed to attain normative data and cut-off scores for four commonly employed neuropsychological tools, administered in English, on a population of black, South African, Xhosa-speaking people (N = 33), who attended a former DET-type school in the Eastern Cape, with a Grade 11-12 level of education, in the age range of 18 - 40 years. The targeted measures included the TOMM, the Rey-15 Item Memory Test, the Digit Span subtest of the WAIS-III, and the Trail Making Test. The obtained scores were poorer than the previously published cut-offs for at least one component of each of the tests investigated, except the TOMM. The fmdings of this study highlight the important role that the factors of culture, quality of education, and language play in neuropsychological test performance.
- Full Text:
- Date Issued: 2009
Obstacles faced by news journalists in investigative reporting: analysis of four Botswana newspapers, June 2008 - October 2008
- Authors: Pule, Kediretswe
- Date: 2009
- Subjects: Investigative reporting , Journalism -- Political aspects , Journalists -- Legal status, laws, etc
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8398 , http://hdl.handle.net/10948/869 , Investigative reporting , Journalism -- Political aspects , Journalists -- Legal status, laws, etc
- Description: In this research study, the researcher investigates obstacles faced by news journalists in investigative journalism in a democracy as experienced in Botswana. Investigative journalism and democracy have a symbiotic relationship. This relationship serves to make the public sensitive about, and aware of, injustices and undemocratic practices and it could, ultimately, contribute significantly to the process of democratization (Faure 2005: 155). Unfortunately, in their endeavor to keep up with the ethos of investigative journalism, journalists meet obstacles that range from legal to financial issues. The author investigates those factors that reporters in Botswana rate as having the greatest impact on their investigative efforts. The study also assesses the attitudes of journalists in the country towards the roles and responsibilities of the fourth estate, which supports investigative reporting. Investigative journalism is centered on disclosure, described by six elements: public interest, theme, accuracy, follow-up reports, consequences and questioning the status quo (Faure 2005:160; Marron 1995:1). The researcher interrogated the current practice of investigative journalism in newsrooms in the Botswana context, by means of a self-administered questionnaire. A cumulative sum of scores of each rank order for each obstacle was used to observe the one rated the most impeding by Botswana journalists. Elementary descriptive statistics in the form of percentages were used to assess attitudes of Botswana journalists towards investigative journalism. The same method was used to assess the proportion of investigative stories in four sampled Botswana newspapers. The contents of the respective newspapers were assessed against the five elements of investigative reporting that include: theme, public interest, questioning the status quo, accuracy, follow-up reports and consequences.
- Full Text:
- Date Issued: 2009
- Authors: Pule, Kediretswe
- Date: 2009
- Subjects: Investigative reporting , Journalism -- Political aspects , Journalists -- Legal status, laws, etc
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8398 , http://hdl.handle.net/10948/869 , Investigative reporting , Journalism -- Political aspects , Journalists -- Legal status, laws, etc
- Description: In this research study, the researcher investigates obstacles faced by news journalists in investigative journalism in a democracy as experienced in Botswana. Investigative journalism and democracy have a symbiotic relationship. This relationship serves to make the public sensitive about, and aware of, injustices and undemocratic practices and it could, ultimately, contribute significantly to the process of democratization (Faure 2005: 155). Unfortunately, in their endeavor to keep up with the ethos of investigative journalism, journalists meet obstacles that range from legal to financial issues. The author investigates those factors that reporters in Botswana rate as having the greatest impact on their investigative efforts. The study also assesses the attitudes of journalists in the country towards the roles and responsibilities of the fourth estate, which supports investigative reporting. Investigative journalism is centered on disclosure, described by six elements: public interest, theme, accuracy, follow-up reports, consequences and questioning the status quo (Faure 2005:160; Marron 1995:1). The researcher interrogated the current practice of investigative journalism in newsrooms in the Botswana context, by means of a self-administered questionnaire. A cumulative sum of scores of each rank order for each obstacle was used to observe the one rated the most impeding by Botswana journalists. Elementary descriptive statistics in the form of percentages were used to assess attitudes of Botswana journalists towards investigative journalism. The same method was used to assess the proportion of investigative stories in four sampled Botswana newspapers. The contents of the respective newspapers were assessed against the five elements of investigative reporting that include: theme, public interest, questioning the status quo, accuracy, follow-up reports and consequences.
- Full Text:
- Date Issued: 2009
On the evaluation of spectral effects on photovoltaic modules performance parameters and hotspots in solar cells
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
- Date Issued: 2009
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
- Date Issued: 2009
Optimizing the recovery rate of Mycobacterium species from gastric lavages in children at an urban Zambian hospital
- Authors: Lubasi, David
- Date: 2009
- Subjects: Mycobacterium , Tuberculosis in children -- Diagnosis -- Zambia
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10118 , http://hdl.handle.net/10948/1440 , Mycobacterium , Tuberculosis in children -- Diagnosis -- Zambia
- Description: Tuberculosis (TB) has re-emerged as a major worldwide public health hazard with increasing incidence among adults and children. Although cases among children represent a small percentage of all TB cases, they are a reservoir from which many adult cases will arise. Estimates indicate that 9 million people develop TB annually, out of which 1 million (11 percent) occur in children less than 15 years old. Childhood tuberculosis is on the increase worldwide because of persisting inability to conform the diagnosis, leading to a large number of children dying of undiagnosed tuberculosis. Diagnosis of pulmonary tuberculosis has depended on bacteriological examination of sputum. In most of the developing countries sputum smear microscopy has been used as it has been found to be cheap and relative efficient. As a result of the high TB burden, there is an urgent need for improved methods of laboratory diagnosis of TB. This is especially needed in children were diagnosis is more challenging as mycobacteria is being detected in fewer than 50 percent of the cases. Children cannot produce adequate sputum samples for examination. Their sputum samples, if produced, has a low bacterial yield and making detection of mycobacteria by using the smear microscopy difficult. Therefore, gastric lavages from children are being recommended as the best specimen for culture. In this study, gastric lavages from 408 children suspected of having tuberculosis were examined for the recovery of mycobacteria. Recovery was optimized by the use of the relatively new non-radiometric fully automated BACTEC MGIT 960. BACTEC MGIT 960 produced a positivity rate of 27.2 percent against 17.2 percent that of Lowenstein-Jensen (L-J) media, which is a conventional culture method used widely. The direct microscopy which is the cheapest traditional method used in diagnosis of tuberculosis (TB) yielded a 5.6 percent positive rate. The BACTEC MGIT 960 had also a very high isolate detection rate of 98.2 percent compared to that of L-J media of 61.9 percent, and only 20.4 percent were detected with the direct microscopy. On time taken to detection or mean time to detection (TTD) of v isolates, the BACTEC MGIT 960 technique had a shorter mean time to detection, 12.5 days as compared to 34.3 days shown by the L-J media technique. The study showed that children normally get tuberculosis from adult members of the household. A positive TB case was found in the households of 55.4 percent of the suspects. The study has found that 46.4 percent of the children below the age of 4 years developed the disease, compared to 10.5 percent the older children in the age group 10 to 14 years. The study found that tuberculosis in children is mainly caused by Mycobacterium tuberculosis. Out of the 113 isolates detected, 110 (97.3 percent) were M. tuberculosis. The remaining 2.7 percent were the non-tuberculous M. avium complex and M. kansasii. It was inconclusive whether the 2.7 percent of other species were causing tuberculosis and this need to be studied further.
- Full Text:
- Date Issued: 2009
- Authors: Lubasi, David
- Date: 2009
- Subjects: Mycobacterium , Tuberculosis in children -- Diagnosis -- Zambia
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:10118 , http://hdl.handle.net/10948/1440 , Mycobacterium , Tuberculosis in children -- Diagnosis -- Zambia
- Description: Tuberculosis (TB) has re-emerged as a major worldwide public health hazard with increasing incidence among adults and children. Although cases among children represent a small percentage of all TB cases, they are a reservoir from which many adult cases will arise. Estimates indicate that 9 million people develop TB annually, out of which 1 million (11 percent) occur in children less than 15 years old. Childhood tuberculosis is on the increase worldwide because of persisting inability to conform the diagnosis, leading to a large number of children dying of undiagnosed tuberculosis. Diagnosis of pulmonary tuberculosis has depended on bacteriological examination of sputum. In most of the developing countries sputum smear microscopy has been used as it has been found to be cheap and relative efficient. As a result of the high TB burden, there is an urgent need for improved methods of laboratory diagnosis of TB. This is especially needed in children were diagnosis is more challenging as mycobacteria is being detected in fewer than 50 percent of the cases. Children cannot produce adequate sputum samples for examination. Their sputum samples, if produced, has a low bacterial yield and making detection of mycobacteria by using the smear microscopy difficult. Therefore, gastric lavages from children are being recommended as the best specimen for culture. In this study, gastric lavages from 408 children suspected of having tuberculosis were examined for the recovery of mycobacteria. Recovery was optimized by the use of the relatively new non-radiometric fully automated BACTEC MGIT 960. BACTEC MGIT 960 produced a positivity rate of 27.2 percent against 17.2 percent that of Lowenstein-Jensen (L-J) media, which is a conventional culture method used widely. The direct microscopy which is the cheapest traditional method used in diagnosis of tuberculosis (TB) yielded a 5.6 percent positive rate. The BACTEC MGIT 960 had also a very high isolate detection rate of 98.2 percent compared to that of L-J media of 61.9 percent, and only 20.4 percent were detected with the direct microscopy. On time taken to detection or mean time to detection (TTD) of v isolates, the BACTEC MGIT 960 technique had a shorter mean time to detection, 12.5 days as compared to 34.3 days shown by the L-J media technique. The study showed that children normally get tuberculosis from adult members of the household. A positive TB case was found in the households of 55.4 percent of the suspects. The study has found that 46.4 percent of the children below the age of 4 years developed the disease, compared to 10.5 percent the older children in the age group 10 to 14 years. The study found that tuberculosis in children is mainly caused by Mycobacterium tuberculosis. Out of the 113 isolates detected, 110 (97.3 percent) were M. tuberculosis. The remaining 2.7 percent were the non-tuberculous M. avium complex and M. kansasii. It was inconclusive whether the 2.7 percent of other species were causing tuberculosis and this need to be studied further.
- Full Text:
- Date Issued: 2009
Organisational restructuring and its impact on job satisfaction, career moblity and stress levels of employees at Lesotho Highlands Development Authority
- Authors: Mahloane, Katiso William
- Date: 2009
- Subjects: Employee morale , Organizational change , Employees -- Attitudes -- Evaluation , Job satisfaction , Stress management
- Language: English
- Type: Thesis , Masters , M Admin
- Identifier: vital:11648 , http://hdl.handle.net/10353/188 , Employee morale , Organizational change , Employees -- Attitudes -- Evaluation , Job satisfaction , Stress management
- Description: Organisations today are in a state of ever accelerating rate of change. Globalisation of the economy, increasing competition, technological innovation as well as global competition are seen to bring about the ever-accelerating pace of change in the working environment worldwide (Christen 2005:241). For this reason, employees are challenged by changes in their careers that they never anticipated, changes which in the long-run, result in stress conditions that bring negative consequences for both employees and the organisation in their wake. This chapter will provide the background to the topic of the study and survey what other studies have revealed about it. The objectives of the study, the research questions, the research objectives over and above the necessary hypotheses will also be mentioned and to conclude, the chapter will provide the theoretical framework in support of this study.As we may be aware, we live in a world of change, where everything constantly has reformed. Organisations are also part of that big change especially in the new millennium where re-engineering, downsizing, outsourcing and restructuring have become common terms associated with many organisations. Although a number of studies have tried to determine how organisational restructuring benefits the organisation, little has been done to find out how the welfare of employees is affected by the restructuring initiatives. This study investigates the perceptions that employees have of organisational restructuring. It investigates how their job satisfaction, career mobility and their stress levels are affected by restructuring process after the restructuring process as well the stress that such employees experience due to restructuring. A survey was conducted at Lesotho Highlands Development Authority, where data was obtained from 121 respondents and statistically analysed. The findings reflect a negative association between restructuring and stress levels and career mobility. The findings show that job satisfaction was still experienced by the employees at LHDA and that most respondents see organisational restructuring as something that benefits the organisation and has little to do with the interests of the workers.
- Full Text:
- Date Issued: 2009
- Authors: Mahloane, Katiso William
- Date: 2009
- Subjects: Employee morale , Organizational change , Employees -- Attitudes -- Evaluation , Job satisfaction , Stress management
- Language: English
- Type: Thesis , Masters , M Admin
- Identifier: vital:11648 , http://hdl.handle.net/10353/188 , Employee morale , Organizational change , Employees -- Attitudes -- Evaluation , Job satisfaction , Stress management
- Description: Organisations today are in a state of ever accelerating rate of change. Globalisation of the economy, increasing competition, technological innovation as well as global competition are seen to bring about the ever-accelerating pace of change in the working environment worldwide (Christen 2005:241). For this reason, employees are challenged by changes in their careers that they never anticipated, changes which in the long-run, result in stress conditions that bring negative consequences for both employees and the organisation in their wake. This chapter will provide the background to the topic of the study and survey what other studies have revealed about it. The objectives of the study, the research questions, the research objectives over and above the necessary hypotheses will also be mentioned and to conclude, the chapter will provide the theoretical framework in support of this study.As we may be aware, we live in a world of change, where everything constantly has reformed. Organisations are also part of that big change especially in the new millennium where re-engineering, downsizing, outsourcing and restructuring have become common terms associated with many organisations. Although a number of studies have tried to determine how organisational restructuring benefits the organisation, little has been done to find out how the welfare of employees is affected by the restructuring initiatives. This study investigates the perceptions that employees have of organisational restructuring. It investigates how their job satisfaction, career mobility and their stress levels are affected by restructuring process after the restructuring process as well the stress that such employees experience due to restructuring. A survey was conducted at Lesotho Highlands Development Authority, where data was obtained from 121 respondents and statistically analysed. The findings reflect a negative association between restructuring and stress levels and career mobility. The findings show that job satisfaction was still experienced by the employees at LHDA and that most respondents see organisational restructuring as something that benefits the organisation and has little to do with the interests of the workers.
- Full Text:
- Date Issued: 2009
Organizational culture and innovation: the case of the Namibian National Institute for Educational Development
- Piepmeyer, Gernot Maximilian
- Authors: Piepmeyer, Gernot Maximilian
- Date: 2009
- Subjects: National Institute for Educational Development (Namibia) Corporate culture -- Namibia Organizational behavior -- Namibia Technological innovations -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1685 , http://hdl.handle.net/10962/d1003568
- Description: The purpose of my research is to diagnose the organizational culture of the National Institute for Educational Development [NIED] , in particular to determine whether it is conducive to innovation, as was envisaged at the time of its inception. The diagnosis of NIED's organizational culture was done by using a hybrid qualitative and quantitative case study. A questionnaire, the Cameron and Quinn's Organizational Culture Assessment Instrument [OCAI], was given to all professional members at NIED, while six members of the NIED organization were interviewed. It emerged from the data, first, that the characteristics of the dominant NIED culture, using Cameron and Quinn's six dimensions of culture that produced an "overall culture profile" of NIED, are not likely to enhance innovativeness. Nevertheless, there is a strong preference towards a culture type favourable to innovation. Second, there are cultural factors antithetical to an innovative organizational culture. These include poor information flow and a lack of communication, negligible crossfunction interaction and freedom, and constraining hierarchical and bureaucratic structures. Third, NIED has, in the form of a "green paper," a set of critical norms, values and assumptions that characterize the culture of innovative organizations. Finally, there is evidence of the presence of cultural characteristics conducive to an innovative organizational culture. These include: learning how to learn; being pro-active in initiating change and innovativeness; and sustaining momentum, consistency and perseverance. The discrepancy between the existing organizational culture and the preferred organizational culture revealed by the overall cultural profile can be explained by the fact that the norms, values and assumptions that characterize the culture of innovative organizations and the cultural characteristics conducive to an innovative organizational culture are not fully infused into the whole organization. There is a tension between NIED's bureaucratic nature and its innovative mission. Organizational culture change, where NIED's structures and processes are aligned with its espoused vision and mission, is needed in order for it to be better placed to achieve its original pioneering mandate.
- Full Text:
- Date Issued: 2009
- Authors: Piepmeyer, Gernot Maximilian
- Date: 2009
- Subjects: National Institute for Educational Development (Namibia) Corporate culture -- Namibia Organizational behavior -- Namibia Technological innovations -- Namibia Education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1685 , http://hdl.handle.net/10962/d1003568
- Description: The purpose of my research is to diagnose the organizational culture of the National Institute for Educational Development [NIED] , in particular to determine whether it is conducive to innovation, as was envisaged at the time of its inception. The diagnosis of NIED's organizational culture was done by using a hybrid qualitative and quantitative case study. A questionnaire, the Cameron and Quinn's Organizational Culture Assessment Instrument [OCAI], was given to all professional members at NIED, while six members of the NIED organization were interviewed. It emerged from the data, first, that the characteristics of the dominant NIED culture, using Cameron and Quinn's six dimensions of culture that produced an "overall culture profile" of NIED, are not likely to enhance innovativeness. Nevertheless, there is a strong preference towards a culture type favourable to innovation. Second, there are cultural factors antithetical to an innovative organizational culture. These include poor information flow and a lack of communication, negligible crossfunction interaction and freedom, and constraining hierarchical and bureaucratic structures. Third, NIED has, in the form of a "green paper," a set of critical norms, values and assumptions that characterize the culture of innovative organizations. Finally, there is evidence of the presence of cultural characteristics conducive to an innovative organizational culture. These include: learning how to learn; being pro-active in initiating change and innovativeness; and sustaining momentum, consistency and perseverance. The discrepancy between the existing organizational culture and the preferred organizational culture revealed by the overall cultural profile can be explained by the fact that the norms, values and assumptions that characterize the culture of innovative organizations and the cultural characteristics conducive to an innovative organizational culture are not fully infused into the whole organization. There is a tension between NIED's bureaucratic nature and its innovative mission. Organizational culture change, where NIED's structures and processes are aligned with its espoused vision and mission, is needed in order for it to be better placed to achieve its original pioneering mandate.
- Full Text:
- Date Issued: 2009
Patterns and determinants of species richness in mesic temparate grasslands of South Africa
- Authors: Hoare, David Barry
- Date: 2009
- Subjects: Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10613 , http://hdl.handle.net/10948/1275 , Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Description: The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.
- Full Text:
- Date Issued: 2009
- Authors: Hoare, David Barry
- Date: 2009
- Subjects: Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10613 , http://hdl.handle.net/10948/1275 , Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Description: The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.
- Full Text:
- Date Issued: 2009
Phases of sustainable development in small and medium enterprise (SME) retail outlets
- Authors: Brower, Marlon
- Date: 2009
- Subjects: Sustainable development -- South Africa -- Nelson Mandela Bay Municipality , Small business -- South Africa -- Nelson Mandela Bay Municipality , Outlet stores -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8806 , http://hdl.handle.net/10948/d1018506
- Description: SMEs play a vital role in the country. For the purpose of the study the focus was on SMEs in the Nelson Mandela Bay Municipality Jurisdiction. Businesses which met the SME criteria (refer to Chapter 1, Section 1.7.1), (Du Plessis, 1996: 162; Marx et al., 1998: 728) were included in this study. The study is formed around the aspects of business which contribute to the growth of the business in the long term. A specific study was conducted on the ethnic entrepreneur and the aspects that influence business growth. There are many factors which influence the growth of the business; for the purpose of this study, a specific focus was placed on: (1) knowledge with regard to business; (2) entrepreneurial culture; (3) brand management; (4) location of the business; (5) business relationships; and (6) cultural influences. These variables will determine how the growth of the business is ultimately influenced. The research can also discover from respondents what they view as important in their lives. The study then goes further to analyse whether the independent variables, as reacted to by the respondents, have a significant or non-significant effect on growth.
- Full Text:
- Date Issued: 2009
- Authors: Brower, Marlon
- Date: 2009
- Subjects: Sustainable development -- South Africa -- Nelson Mandela Bay Municipality , Small business -- South Africa -- Nelson Mandela Bay Municipality , Outlet stores -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8806 , http://hdl.handle.net/10948/d1018506
- Description: SMEs play a vital role in the country. For the purpose of the study the focus was on SMEs in the Nelson Mandela Bay Municipality Jurisdiction. Businesses which met the SME criteria (refer to Chapter 1, Section 1.7.1), (Du Plessis, 1996: 162; Marx et al., 1998: 728) were included in this study. The study is formed around the aspects of business which contribute to the growth of the business in the long term. A specific study was conducted on the ethnic entrepreneur and the aspects that influence business growth. There are many factors which influence the growth of the business; for the purpose of this study, a specific focus was placed on: (1) knowledge with regard to business; (2) entrepreneurial culture; (3) brand management; (4) location of the business; (5) business relationships; and (6) cultural influences. These variables will determine how the growth of the business is ultimately influenced. The research can also discover from respondents what they view as important in their lives. The study then goes further to analyse whether the independent variables, as reacted to by the respondents, have a significant or non-significant effect on growth.
- Full Text:
- Date Issued: 2009
Phenolic compounds in water and the implications for rapid detection of indicator micro-organisms using ß-D-Galactosidase and ß-D-Glucuronidase
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
Photophysical and photochemical behaviour of metallophthalocyanines effect of nanoparticles and molecules of biological importance
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
- Full Text:
- Date Issued: 2009
- Authors: Idowu, Mopelola Abidemi
- Date: 2009
- Subjects: Electrochemistry Phthalocyanines Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4329 , http://hdl.handle.net/10962/d1004990
- Description: Syntheses, spectral, photophysical and photochemical studies of some neutral, anionic and cationic metallophthalocyanine derivatives are presented. The effects of central metal ions, solvents, aggregation, surfactant, nanoparticles and bovine serum albumin on the photophysical and photochemical behaviour are investigated. Mercaptocarboxylic acid stabilized CdTe quantum dots (QDs) were used as energy donors to anionic water-soluble MPcs through Förster resonance energy transfer (FRET). Energy transfer (ET) from the QDs to the MPcs occurred upon photoexcitation of the QDs. An enhancement in efficiency of ET with the nature of the cappings on the QDs was observed with few occurrences of a non-Förster type ET. QDs were found to improve the photophysicochemical behaviour of the MPcs, with the possibility of indirect production of singlet oxygen (Φ[subscript Δ]) via FRET mechanism. Interaction of the QDs with cationic water-souble MPcs produced ion-pair complexes resulting in aggregates due to strong electronic coupling. The stoichiometry of the reaction and association constants are evaluated by the continuous variation method. Improved photophysicochemical behaviour with no spectral alterations was observed in MPcs in the presence of magnetic fluid. Complexes showed high triplet quantum yields with corresponding long lifetimes and high photostability. Elucidation of the results of the interaction of bovine serum albumin (BSA) with MPcs or QDs is presented. Increased efficiency of Φ[subscript Δ] generation of MPcs in the presence of BSA coupled with large binding constants, suggesting strong interaction of the MPcs with BSA was observed. Enhanced emission intensity of QDs when linked to or in a mixture with BSA due to radiationless recombination at the surface vacancies was also observed. The study revealed positive deviation from Stern-Volmer relationship suggesting the occurrence of static and dynamic mechanisms of quenching together. Fluorescence quenching of the MPcs by benzoquinone, analysed by Stern-Volmer relationship is also presented; the results were employed in determining fluorescence lifetimes of the complexes. Photoelectrochemical characteristics of MPc-sensitized electrodeposited ZnO thin films were studied; ZnOCPc / ZnO films have been improved to an incident photon-to-currentconversion (IPCE) value of 31.1 % with an absorbed photon-to-current conversion (APCE) of 59.6 %. The best obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films. Fluorescent-magnetic nanocomposite with excellent photophysical properties which can be exploited for combined photodynamic and hyperthermia therapies is also presented.
- Full Text:
- Date Issued: 2009
Photosynthetic and evolutionary determinants of the response of selected C3 and C4 (NADP-ME) grasses to fire
- Authors: Martin, Tarryn
- Date: 2009
- Subjects: Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4211 , http://hdl.handle.net/10962/d1003780 , Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Description: Species possess characteristics that are considered adapted to burning and these allow them to outcompete species and dominate in fire prone environments. It has therefore been proposed that fire might have played a critical role in the observed expansion of the grasslands, during the late Miocene. The aim of this study was (i) to investigate whether plant response to fire was a result of physiology or (ii) whether it was due to phylogenetic history. This was achieved by doing a pair-wise comparison between Panicoideae (and Panicoideae) and non-Panicoideae (Danthonioideae and Aristidoideae) species. Pre-fire characteristics, that would enhance fire frequency and assist with plant recovery after burning, were compared across phylogenies and photosynthetic type. Post fire plant recovery was then followed in a field and pot comparison which examined the re-growth of the leaf canopy area, leaf mass, above-ground biomass and the cost of this to the below-ground biomass. The pre-fire characteristics showed both a photosynthetic and phylogenetic response. It was found that the species showed a greater canopy death during winter and had a lower moisture content than the species. These characteristics would potentially contribute towards a larger fuel load in the species. However, the comparison of the dead standing biomass at the end of winter and the below-ground biomass, showed a phylogenetic response with the Panicoideae having a proportionally larger dead standing biomass and below-ground biomass than the non-Panicoideae. These results suggest that not only did the Panicoideae have a larger potential fuel load but that they also shunted carbon below-ground, enabling a fast recovery after being burned. The post-fire results were more strongly determined by phylogeny than by photosynthetic type. The Panicoideae recovered faster and more completely than the non-Panicoideae grasses, possibly contributing to their success and expansion under conditions of increased fire frequency. Although recovery of the and Panicoideae were similar, frequently burnt grasslands are dominated by the Panicoideae. Hence, this dominance cannot be explained by differences in their fire responses and may be determined by the post-fire environmental conditions that potentially advantage species possessing the photosynthetic pathway. Panicoideae dominance is limited to mesic environments where fire is the likely driver of grassland expansion while more arid environments are dominated by non-Panicoideae species. Representative species from these non-Panicoid subfamilies showed poor recovery after fire. This suggests that factors other than fire were the likely drivers of these xeric grassland expansions. The ability of these subfamilies, and particularly the species, to cope with drought remains a likely selective mechanism that requires further research.
- Full Text:
- Date Issued: 2009
- Authors: Martin, Tarryn
- Date: 2009
- Subjects: Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4211 , http://hdl.handle.net/10962/d1003780 , Photosynthesis , Carbon -- Metabolism , Grasses -- Adaptation , Plants -- Effect of fires on , Grasses -- Research , Grasses -- Physiology , Grasses -- Evolution , Grasslands -- Research
- Description: Species possess characteristics that are considered adapted to burning and these allow them to outcompete species and dominate in fire prone environments. It has therefore been proposed that fire might have played a critical role in the observed expansion of the grasslands, during the late Miocene. The aim of this study was (i) to investigate whether plant response to fire was a result of physiology or (ii) whether it was due to phylogenetic history. This was achieved by doing a pair-wise comparison between Panicoideae (and Panicoideae) and non-Panicoideae (Danthonioideae and Aristidoideae) species. Pre-fire characteristics, that would enhance fire frequency and assist with plant recovery after burning, were compared across phylogenies and photosynthetic type. Post fire plant recovery was then followed in a field and pot comparison which examined the re-growth of the leaf canopy area, leaf mass, above-ground biomass and the cost of this to the below-ground biomass. The pre-fire characteristics showed both a photosynthetic and phylogenetic response. It was found that the species showed a greater canopy death during winter and had a lower moisture content than the species. These characteristics would potentially contribute towards a larger fuel load in the species. However, the comparison of the dead standing biomass at the end of winter and the below-ground biomass, showed a phylogenetic response with the Panicoideae having a proportionally larger dead standing biomass and below-ground biomass than the non-Panicoideae. These results suggest that not only did the Panicoideae have a larger potential fuel load but that they also shunted carbon below-ground, enabling a fast recovery after being burned. The post-fire results were more strongly determined by phylogeny than by photosynthetic type. The Panicoideae recovered faster and more completely than the non-Panicoideae grasses, possibly contributing to their success and expansion under conditions of increased fire frequency. Although recovery of the and Panicoideae were similar, frequently burnt grasslands are dominated by the Panicoideae. Hence, this dominance cannot be explained by differences in their fire responses and may be determined by the post-fire environmental conditions that potentially advantage species possessing the photosynthetic pathway. Panicoideae dominance is limited to mesic environments where fire is the likely driver of grassland expansion while more arid environments are dominated by non-Panicoideae species. Representative species from these non-Panicoid subfamilies showed poor recovery after fire. This suggests that factors other than fire were the likely drivers of these xeric grassland expansions. The ability of these subfamilies, and particularly the species, to cope with drought remains a likely selective mechanism that requires further research.
- Full Text:
- Date Issued: 2009
Phylogeography and epifauna of two intertidal seaweeds on the coast of South Africa
- Authors: Mmonwa, Lucas Kolobe
- Date: 2009
- Subjects: Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5738 , http://hdl.handle.net/10962/d1005424 , Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Description: Southern African biogeographic boundaries delimit the phylogeographic distribution of some coastal and estuarine invertebrates. This study investigated the impact of these boundaries on the phylogeographic distribution of two intertidal red seaweeds, Gelidium pristoides and Hypnea spicifera using the mitochondrial Cox2-3 spacer and the nuclear ITS1 regions. G. pristoides spores have short distance-dispersal, while long distance-dispersal is more likely in H. spicifera via spores and drifting fertile thallus fragments. Both markers revealed a south-western and south-eastern lineage within G. pristoides but the breaks between lineages do not coincide with any recognised biogeographic limits. The Cox2-3 spacer revealed a boundary between the two lineages at the Alexandria Coastal Dunefield (ACD) and ITS1 at the Gamtoos-Van Stadens Dunefields (GVD) which is approximately 80km west of the ACD. The minor difference between the two markers regarding location of the phylogeographic boundary is probably due to the dating differences between the two dunefields. The ACD as developed currently is superimposed on the ancient dunefields which formed during the Pleistocene, coinciding with the Cox2-3 spacer sequences divergence which dates back 500,000 - 580,000 years. The GVD formed during the Holocene (6,500 - 4,000 years ago), coinciding with the ITS1 sequences divergence which dates 4,224 - 4,928 years ago. Thus, these phylogeographic boundaries probably appeared without the influence of biogeographic boundaries, but rather due to the lack of suitable habitat in the dunefields, coupled with short dispersal-distances of the spores. Analysis of the ITS1 and Cox2-3 spacer regions in H. spicifera revealed that the species is characterized by uniform genetic structure along the coastline. This reflects the species`s potential for long range expansion as it inhabits both the intertidal and subtidal zones; and this presumably leads to high gene flow among populations. The ITS1 sequences showed minimal genetic variation of one substitution between the gametophyte and tetrasporophyte generations within H. spicifera. This suggests the predominance of asexual reproduction, which reduces gene flow and fixes alleles between generations. ANOSIM and Bray-Curtis cluster analyses showed scale-dependant variation in the abundances of epifauna (mainly amphipod, isopod, mollusc and polychaete species) on G. pristoides. At small local (within site) and large (among sites) scales, there were weak and no structure in epifaunal abundances respectively. However, at larger, biogeographic scales, samples from the same biogeographic region tended to be clustered together. Thus, there was a group containing predominantly south coast samples and a group containing east coast samples mixed with the remaining south coast samples. Such scale-dependant variation in epifaunal abundances is probably due to the effects of factors driving species richness at small local (within site) scales (e.g. wave exposure, seaweed biomass) and at larger, biogeographic scales (e.g. surface sea temperature). Moreover, at very small (individual samples) scales; there was no correlation between epifauna composition and genotype of the seaweed. Seaweed samples characterized by distinct ITS1 or Cox2-3 spacer sequences did not show any significant differences in epifaunal composition. Although the distributional pattern of the epifaunal community observed at large biogeographic scale is not clear, it seems to be associated with the biogeographic regions. However, phylogeographic distribution of Gelidium pristoides is not connected to biogeographic regions. Thus, at larger, biogeographic scales, there is no correlation between phylogeographic distribution of G. pristoides and distribution of the associated fauna
- Full Text:
- Date Issued: 2009
- Authors: Mmonwa, Lucas Kolobe
- Date: 2009
- Subjects: Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5738 , http://hdl.handle.net/10962/d1005424 , Phylogeography -- South Africa , Marine algae -- South Africa , Red algae -- South Africa , Gelidium -- South Africa
- Description: Southern African biogeographic boundaries delimit the phylogeographic distribution of some coastal and estuarine invertebrates. This study investigated the impact of these boundaries on the phylogeographic distribution of two intertidal red seaweeds, Gelidium pristoides and Hypnea spicifera using the mitochondrial Cox2-3 spacer and the nuclear ITS1 regions. G. pristoides spores have short distance-dispersal, while long distance-dispersal is more likely in H. spicifera via spores and drifting fertile thallus fragments. Both markers revealed a south-western and south-eastern lineage within G. pristoides but the breaks between lineages do not coincide with any recognised biogeographic limits. The Cox2-3 spacer revealed a boundary between the two lineages at the Alexandria Coastal Dunefield (ACD) and ITS1 at the Gamtoos-Van Stadens Dunefields (GVD) which is approximately 80km west of the ACD. The minor difference between the two markers regarding location of the phylogeographic boundary is probably due to the dating differences between the two dunefields. The ACD as developed currently is superimposed on the ancient dunefields which formed during the Pleistocene, coinciding with the Cox2-3 spacer sequences divergence which dates back 500,000 - 580,000 years. The GVD formed during the Holocene (6,500 - 4,000 years ago), coinciding with the ITS1 sequences divergence which dates 4,224 - 4,928 years ago. Thus, these phylogeographic boundaries probably appeared without the influence of biogeographic boundaries, but rather due to the lack of suitable habitat in the dunefields, coupled with short dispersal-distances of the spores. Analysis of the ITS1 and Cox2-3 spacer regions in H. spicifera revealed that the species is characterized by uniform genetic structure along the coastline. This reflects the species`s potential for long range expansion as it inhabits both the intertidal and subtidal zones; and this presumably leads to high gene flow among populations. The ITS1 sequences showed minimal genetic variation of one substitution between the gametophyte and tetrasporophyte generations within H. spicifera. This suggests the predominance of asexual reproduction, which reduces gene flow and fixes alleles between generations. ANOSIM and Bray-Curtis cluster analyses showed scale-dependant variation in the abundances of epifauna (mainly amphipod, isopod, mollusc and polychaete species) on G. pristoides. At small local (within site) and large (among sites) scales, there were weak and no structure in epifaunal abundances respectively. However, at larger, biogeographic scales, samples from the same biogeographic region tended to be clustered together. Thus, there was a group containing predominantly south coast samples and a group containing east coast samples mixed with the remaining south coast samples. Such scale-dependant variation in epifaunal abundances is probably due to the effects of factors driving species richness at small local (within site) scales (e.g. wave exposure, seaweed biomass) and at larger, biogeographic scales (e.g. surface sea temperature). Moreover, at very small (individual samples) scales; there was no correlation between epifauna composition and genotype of the seaweed. Seaweed samples characterized by distinct ITS1 or Cox2-3 spacer sequences did not show any significant differences in epifaunal composition. Although the distributional pattern of the epifaunal community observed at large biogeographic scale is not clear, it seems to be associated with the biogeographic regions. However, phylogeographic distribution of Gelidium pristoides is not connected to biogeographic regions. Thus, at larger, biogeographic scales, there is no correlation between phylogeographic distribution of G. pristoides and distribution of the associated fauna
- Full Text:
- Date Issued: 2009
Planning and managing curriculum implementation in rural schools: an investigation
- Authors: Labane, Nokubonga
- Date: 2009
- Subjects: Curriculum planning -- South Africa , Teacher participation in curriculum planning , Education -- South Africa -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9522 , http://hdl.handle.net/10948/998 , Curriculum planning -- South Africa , Teacher participation in curriculum planning , Education -- South Africa -- Curricula
- Description: Fleisch (2002) and Jansen and Christie (1999) hold that implementation of the national school curriculum in post-apartheid South Africa was riddled with uncertainties, ineffective classroom management and a general lack of academic performance by learners, mainly as a result of inadequate training and support (SMTs) to support the implementation process through proper planning and subsequent management of the implementation (Rogan and Grayson, 2003:1172-1195). Middlewood (2003a: 66- 68) thus assigns the primary responsibility of planning, managing and overseeing the curriculum implementation process to the SMT. Research problem and question 1 In the context of this study, the School Management Team (SMT) includes the school principal, the deputy-principal and the head(s) of department(s) or senior teachers. 4 for teachers in the classroom. Having considered the above essential aspects related to curriculum implementation, there is thus reason to be concerned about the effectiveness of curriculum implementation in South African schools, specifically in rural schools. Due to their remoteness, limited resources, and fluctuating quality of teacher expertise, these schools are often more challenged in terms of curriculum implementation (Delport and Mangwaya, 2008:224). Although there are many factors affecting the (in)effectiveness of implementation, this study regards a school’s curriculum implementation plans and the subsequent management of these implementation plans as crucial to ensuring successful implementation of a new curriculum. The central research problem that guided this study thus relates to the planning and subsequent management of curriculum implementation at school level. The above problem has culminated in the formulation of the following research question: How do selected rural schools plan and manage curriculum implementation?.
- Full Text:
- Date Issued: 2009
- Authors: Labane, Nokubonga
- Date: 2009
- Subjects: Curriculum planning -- South Africa , Teacher participation in curriculum planning , Education -- South Africa -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9522 , http://hdl.handle.net/10948/998 , Curriculum planning -- South Africa , Teacher participation in curriculum planning , Education -- South Africa -- Curricula
- Description: Fleisch (2002) and Jansen and Christie (1999) hold that implementation of the national school curriculum in post-apartheid South Africa was riddled with uncertainties, ineffective classroom management and a general lack of academic performance by learners, mainly as a result of inadequate training and support (SMTs) to support the implementation process through proper planning and subsequent management of the implementation (Rogan and Grayson, 2003:1172-1195). Middlewood (2003a: 66- 68) thus assigns the primary responsibility of planning, managing and overseeing the curriculum implementation process to the SMT. Research problem and question 1 In the context of this study, the School Management Team (SMT) includes the school principal, the deputy-principal and the head(s) of department(s) or senior teachers. 4 for teachers in the classroom. Having considered the above essential aspects related to curriculum implementation, there is thus reason to be concerned about the effectiveness of curriculum implementation in South African schools, specifically in rural schools. Due to their remoteness, limited resources, and fluctuating quality of teacher expertise, these schools are often more challenged in terms of curriculum implementation (Delport and Mangwaya, 2008:224). Although there are many factors affecting the (in)effectiveness of implementation, this study regards a school’s curriculum implementation plans and the subsequent management of these implementation plans as crucial to ensuring successful implementation of a new curriculum. The central research problem that guided this study thus relates to the planning and subsequent management of curriculum implementation at school level. The above problem has culminated in the formulation of the following research question: How do selected rural schools plan and manage curriculum implementation?.
- Full Text:
- Date Issued: 2009
Polarization mode dispersion emulation and the impact of high first-order PMD segments in optical telecommunication systems
- Authors: Musara, Vitalis
- Date: 2009
- Subjects: Optical communications , Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10519 , http://hdl.handle.net/10948/1138 , Optical communications , Fiber optics , Polarization (Light)
- Description: In this study, focus is centred on the measurement and emulation of first-order (FO-) and second-order (SO-) polarization mode dispersion (PMD). PMD has deleterious effects on the performance of high speed optical transmission network systems from 10 Gb/s and above. The first step was characterising deployed fibres for PMD and monitoring the state of polarization (SOP) light experiences as it propagates through the fibre. The PMD and SOP changes in deployed fibres were stochastic due to varying intrinsic and extrinsic perturbation changes. To fully understand the PMD phenomenon in terms of measurement accuracy, its complex behaviour, its implications, mitigation and compensation, PMD emulation is crucial. This thesis presents emulator designs which fall into different emulator categories. The key to these designs were the PMD equations and background on the PMD phenomenon. The cross product from the concatenation equation was applied in order to determine the coupling angle β (between 0o and 180o) that results in the SO-PMD of the emulator designs to be either adjustable or fixed. The digital delay line (DDL) or single polarization maintaining fibre (PMF) section was used to give a certain amount of FO-PMD but negligible SO-PMD. PMF sections (birefringent sections) were concatenated together to ensure FO- and SO-PMD coexist, emulating deployed fibres. FO- and SO-PMD can be controlled by altering mode coupling (coupling angles) and birefringence distribution. Emulators with PMD statistics approaching the theoretical distributions had high random coupling and several numbers of randomly distributed PMF sections. In addition, the lengths of their PMF sections lie within 20% standard deviation of the mean emulator length. Those emulators with PMD statistics that did not approach the theoretical distributions had limited numbers of randomly distributed PMF sections and mode coupling. Results also show that even when an emulator has high random mode coupling and several numbers of randomly distributed PMFs, its PMD statistics deviates away from expected theoretical distributions in the presence of polarization dependent loss (PDL). The emulators showed that the background autocorrelation function (BACF) approaches zero with increasing number of randomly mode coupled fibre sections. A zero BACF signifies that an emulator has large numbers of randomly distributed PMF sections and its presence means the opposite. The availability of SO-PMD in the emulators made the autocorrelation function (ACF) x asymmetric. In the absence of SO-PMD the ACF for a PMD emulator is symmetric. SO-PMD has no effect on the BACF. Polarization-optical time domain reflectometry (P-OTDR) measurements have shown that certain fibre sections along fibre link lengths have higher FO-PMD (HiFO-PMD) than other sections. This study investigates the impact of a HiFO-PMD section on the overall FO- and SO-PMD, the output state of polarization (SOP) and system performance on deployed fibres (through emulation). Results show that when the wavelength-independent FO-PMD vector of the HiFO-PMD section is greater than the FO-PMD contributions from the rest of the fibre link, the mean FO-PMD of the entire link is biased towards that of the HiFO-PMD section and the SO-PMD increases (β ≠ 0o or 180o) or remains fixed (β = 0o or 180o) depending on the coupling angle β between the HiFO-PMD section and the rest of the fibre link. In addition, the FO-PMD statistics deviates away from the theoretical Maxwellian distribution. However, experimental results show that the HiFO-PMD section has negligible influence on the SOPMD statistical distribution. An increase in the amount of FO-PMD on a HiFO-PMD section reduces the output SOP spread to a given minimum, in this study the minimum was reached when the HiFO-PMD ≥ 35 ps. However, the outcome of the output SOP spread depends on the location of the HiFO-PMD section along the fibre link length. It was found that when the HiFO-PMD section introduces SO-PMD, the bit error rate (BER) is much higher compared to when it does not introduce SO-PMD.
- Full Text:
- Date Issued: 2009
- Authors: Musara, Vitalis
- Date: 2009
- Subjects: Optical communications , Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10519 , http://hdl.handle.net/10948/1138 , Optical communications , Fiber optics , Polarization (Light)
- Description: In this study, focus is centred on the measurement and emulation of first-order (FO-) and second-order (SO-) polarization mode dispersion (PMD). PMD has deleterious effects on the performance of high speed optical transmission network systems from 10 Gb/s and above. The first step was characterising deployed fibres for PMD and monitoring the state of polarization (SOP) light experiences as it propagates through the fibre. The PMD and SOP changes in deployed fibres were stochastic due to varying intrinsic and extrinsic perturbation changes. To fully understand the PMD phenomenon in terms of measurement accuracy, its complex behaviour, its implications, mitigation and compensation, PMD emulation is crucial. This thesis presents emulator designs which fall into different emulator categories. The key to these designs were the PMD equations and background on the PMD phenomenon. The cross product from the concatenation equation was applied in order to determine the coupling angle β (between 0o and 180o) that results in the SO-PMD of the emulator designs to be either adjustable or fixed. The digital delay line (DDL) or single polarization maintaining fibre (PMF) section was used to give a certain amount of FO-PMD but negligible SO-PMD. PMF sections (birefringent sections) were concatenated together to ensure FO- and SO-PMD coexist, emulating deployed fibres. FO- and SO-PMD can be controlled by altering mode coupling (coupling angles) and birefringence distribution. Emulators with PMD statistics approaching the theoretical distributions had high random coupling and several numbers of randomly distributed PMF sections. In addition, the lengths of their PMF sections lie within 20% standard deviation of the mean emulator length. Those emulators with PMD statistics that did not approach the theoretical distributions had limited numbers of randomly distributed PMF sections and mode coupling. Results also show that even when an emulator has high random mode coupling and several numbers of randomly distributed PMFs, its PMD statistics deviates away from expected theoretical distributions in the presence of polarization dependent loss (PDL). The emulators showed that the background autocorrelation function (BACF) approaches zero with increasing number of randomly mode coupled fibre sections. A zero BACF signifies that an emulator has large numbers of randomly distributed PMF sections and its presence means the opposite. The availability of SO-PMD in the emulators made the autocorrelation function (ACF) x asymmetric. In the absence of SO-PMD the ACF for a PMD emulator is symmetric. SO-PMD has no effect on the BACF. Polarization-optical time domain reflectometry (P-OTDR) measurements have shown that certain fibre sections along fibre link lengths have higher FO-PMD (HiFO-PMD) than other sections. This study investigates the impact of a HiFO-PMD section on the overall FO- and SO-PMD, the output state of polarization (SOP) and system performance on deployed fibres (through emulation). Results show that when the wavelength-independent FO-PMD vector of the HiFO-PMD section is greater than the FO-PMD contributions from the rest of the fibre link, the mean FO-PMD of the entire link is biased towards that of the HiFO-PMD section and the SO-PMD increases (β ≠ 0o or 180o) or remains fixed (β = 0o or 180o) depending on the coupling angle β between the HiFO-PMD section and the rest of the fibre link. In addition, the FO-PMD statistics deviates away from the theoretical Maxwellian distribution. However, experimental results show that the HiFO-PMD section has negligible influence on the SOPMD statistical distribution. An increase in the amount of FO-PMD on a HiFO-PMD section reduces the output SOP spread to a given minimum, in this study the minimum was reached when the HiFO-PMD ≥ 35 ps. However, the outcome of the output SOP spread depends on the location of the HiFO-PMD section along the fibre link length. It was found that when the HiFO-PMD section introduces SO-PMD, the bit error rate (BER) is much higher compared to when it does not introduce SO-PMD.
- Full Text:
- Date Issued: 2009
Polymers, catalysts and nanostructures a hybrid approach to biomolecule detection
- Authors: Frith, Kelly-Anne
- Date: 2009
- Subjects: Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3980 , http://hdl.handle.net/10962/d1004039 , Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Description: The main goals in electroanalytical sensing are towards improved sensitivity and selectivity, or specificity, of an analyte. There are several approaches to achieving these goals with the main approach being modification of an electrode surface with synthetic or natural catalysts (enzymes), polymers and also utilisation of nanostructured materials. At present, there is a strong movement towards hybrid sensing which couple different properties of two or more surface modification approaches. In this thesis, a range of these surface modifications were explored for analysis and detection of two main analytes: the amino acid, tryptophan (Trp); and, the neurotransmitter, dopamine (DA). Specifically, this thesis aimed to utilise these methods to enhance the sensitivity and selectivity for Trp over an interferent, the indoleamine, melatonin (Mel); and, DA over the vitamin, ascorbic acid (AA). For Trp detection, immobilisation of an enzyme, Tryptophanase (Trpase) resulted in poor selectivity for the analyte. However, enhanced sensitivity and selectivity was achieved through pH manipulation of the electrolyte medium at a Nafion®-modified electrode surface for both Trp and Mel. At pH 3.0, the Mel and Trp anodic peak potentials were sufficiently resolved allowing for an LOD of 1.60 and 1.62 nM,respectively, and permitting the accurate analysis of Trp in a dietary supplement containing Mel. Multi-walled carbon nanotubes (MWCNTs) suspended in Nafion® exhibited further increases in the signal responses of these analytes at pH 3.0 and 7.4 with minimal change in the resolution of the anodic peaks. A lower sensitivity was, therefore, observed at the Nafion® and MWCNT modified electrode compared to the Nafion®-modified electrode at pH 3.0 with LODs of 0.59 and 0.80 nM exhibited for Trp and Mel, respectively. Enhanced selectivity for Trp in the presence of Mel can be achieved with MWCNTs in the presence of metallotetrasulphonated phthalocyanines (MTSPcs) particularly at pH 3.0, owing to cation exchange effects. However, the lack of sensitivity towards Trp, and even Mel, at this CoTSPc and MWCNT modified electrode remains a drawback. For DA, detection at the MWCNT and Nafion® surface resulted in improved sensitivity over that of both the bare electrode (613.0 nM) and the Nafion® modified electrode (1045.1 nM) with a calculated LOD of 133.9 nM at this layer. Furthermore, improvements in the selectivity of DA were achieved at the Nafion® and MWCNT modified electrode as exclusion of AA (150 μM) was achieved. At the MWCNT and CoTSPc surface, AA was excluded up to 130 μM with sensitivity for DA extending as low as 14.3 nM, far greater than observed for Trp and Mel. These concentrations are well within physiological concentration ranges and represent the most significant solution yet in terms of AA exclusion and enhanced sensitivity for DA. An examination of the surface layering by impedance spectroscopy and atomic force microscopy indicates that the success of the hybrid sensor utilising CoTSPc and MWCNTs lay in improved dispersion of MWCNTs and improved electron transfer kinetics, facilitated by the net charge of the materials present. This thesis, thus, showed the utility of a judicious selection of synthetic and biological catalysts, polymers and carbon nanomaterials towards a hybrid approach to the electrochemical sensing of Trp, Mel, DA and AA with focus on sensitivity and selectivity of these analytes.
- Full Text:
- Date Issued: 2009
- Authors: Frith, Kelly-Anne
- Date: 2009
- Subjects: Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3980 , http://hdl.handle.net/10962/d1004039 , Polymers , Nanostructured materials , Biomolecules , Tryptophan , Melatonin , Electrodes , Electrochemistry , Tryptophan oxygenase
- Description: The main goals in electroanalytical sensing are towards improved sensitivity and selectivity, or specificity, of an analyte. There are several approaches to achieving these goals with the main approach being modification of an electrode surface with synthetic or natural catalysts (enzymes), polymers and also utilisation of nanostructured materials. At present, there is a strong movement towards hybrid sensing which couple different properties of two or more surface modification approaches. In this thesis, a range of these surface modifications were explored for analysis and detection of two main analytes: the amino acid, tryptophan (Trp); and, the neurotransmitter, dopamine (DA). Specifically, this thesis aimed to utilise these methods to enhance the sensitivity and selectivity for Trp over an interferent, the indoleamine, melatonin (Mel); and, DA over the vitamin, ascorbic acid (AA). For Trp detection, immobilisation of an enzyme, Tryptophanase (Trpase) resulted in poor selectivity for the analyte. However, enhanced sensitivity and selectivity was achieved through pH manipulation of the electrolyte medium at a Nafion®-modified electrode surface for both Trp and Mel. At pH 3.0, the Mel and Trp anodic peak potentials were sufficiently resolved allowing for an LOD of 1.60 and 1.62 nM,respectively, and permitting the accurate analysis of Trp in a dietary supplement containing Mel. Multi-walled carbon nanotubes (MWCNTs) suspended in Nafion® exhibited further increases in the signal responses of these analytes at pH 3.0 and 7.4 with minimal change in the resolution of the anodic peaks. A lower sensitivity was, therefore, observed at the Nafion® and MWCNT modified electrode compared to the Nafion®-modified electrode at pH 3.0 with LODs of 0.59 and 0.80 nM exhibited for Trp and Mel, respectively. Enhanced selectivity for Trp in the presence of Mel can be achieved with MWCNTs in the presence of metallotetrasulphonated phthalocyanines (MTSPcs) particularly at pH 3.0, owing to cation exchange effects. However, the lack of sensitivity towards Trp, and even Mel, at this CoTSPc and MWCNT modified electrode remains a drawback. For DA, detection at the MWCNT and Nafion® surface resulted in improved sensitivity over that of both the bare electrode (613.0 nM) and the Nafion® modified electrode (1045.1 nM) with a calculated LOD of 133.9 nM at this layer. Furthermore, improvements in the selectivity of DA were achieved at the Nafion® and MWCNT modified electrode as exclusion of AA (150 μM) was achieved. At the MWCNT and CoTSPc surface, AA was excluded up to 130 μM with sensitivity for DA extending as low as 14.3 nM, far greater than observed for Trp and Mel. These concentrations are well within physiological concentration ranges and represent the most significant solution yet in terms of AA exclusion and enhanced sensitivity for DA. An examination of the surface layering by impedance spectroscopy and atomic force microscopy indicates that the success of the hybrid sensor utilising CoTSPc and MWCNTs lay in improved dispersion of MWCNTs and improved electron transfer kinetics, facilitated by the net charge of the materials present. This thesis, thus, showed the utility of a judicious selection of synthetic and biological catalysts, polymers and carbon nanomaterials towards a hybrid approach to the electrochemical sensing of Trp, Mel, DA and AA with focus on sensitivity and selectivity of these analytes.
- Full Text:
- Date Issued: 2009
Potential of sorghum and finger millet to enhance household food security in Zimbabwe's semi-arid regions: a case study of communal areas in Masvingo Province
- Authors: Mukarumbwa, Peter
- Date: 2009
- Subjects: Food security -- Zimbabwe Case studies , Food supply -- Zimbabwe Case studies , Crops -- Zimbabwe Case studies , Sorghum -- Zimbabwe , Poverty -- Zimbabwe , Millets -- Economic aspects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11186 , http://hdl.handle.net/10353/368 , Food security -- Zimbabwe Case studies , Food supply -- Zimbabwe Case studies , Crops -- Zimbabwe Case studies , Sorghum -- Zimbabwe , Poverty -- Zimbabwe , Millets -- Economic aspects -- Zimbabwe
- Description: Successive droughts, in Zimbabwe compounded by other economic shocks in recent years have resulted in decreased maize productivity amongst the communal farmers most of whom reside in regions IV and V which are considered semi-arid. This has given rise to the need to find alternative food crops, which may be suitable for these areas. Generally, research in the world indicates that sorghum and millet have the potential to end chronic food insecurity in semi-arid areas because of their drought tolerance. Whilst this might be the case, research, government policy and assistance from non-governmental organizations on food crop production in Zimbabwe have shown a continual inclination to maize production in semi-arid areas. However, maize is regarded as a high risk crop in these regions. The main objective of the study was to investigate major factors affecting smallholder farmers in semi-arid areas, from increased production of small grains, specifically sorghum and finger millet. The study was conducted in two rural districts of Masvingo and Gutu, which lie in natural region IV in Masvingo Province. The questionnaire was used as the main tool of inquiry to gather data from households in selected villages within these districts. Questionnaires were administered through face-to-face interviews. The total sample size was 120. The logistic regression model was used to analyze data. The results revealed that, at the 5% level, labour, cattle ownership, farm size, age, extension, yields and access to credit significantly influence sorghum and finger millet production. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of participation in small grain production. In view of these research findings, a policy shift that encourages increased production of finger millet and sorghum in Zimbabwe‟s semi-arid regions is proposed. It is suggested that this may increase household food security in these regions.
- Full Text:
- Date Issued: 2009
- Authors: Mukarumbwa, Peter
- Date: 2009
- Subjects: Food security -- Zimbabwe Case studies , Food supply -- Zimbabwe Case studies , Crops -- Zimbabwe Case studies , Sorghum -- Zimbabwe , Poverty -- Zimbabwe , Millets -- Economic aspects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11186 , http://hdl.handle.net/10353/368 , Food security -- Zimbabwe Case studies , Food supply -- Zimbabwe Case studies , Crops -- Zimbabwe Case studies , Sorghum -- Zimbabwe , Poverty -- Zimbabwe , Millets -- Economic aspects -- Zimbabwe
- Description: Successive droughts, in Zimbabwe compounded by other economic shocks in recent years have resulted in decreased maize productivity amongst the communal farmers most of whom reside in regions IV and V which are considered semi-arid. This has given rise to the need to find alternative food crops, which may be suitable for these areas. Generally, research in the world indicates that sorghum and millet have the potential to end chronic food insecurity in semi-arid areas because of their drought tolerance. Whilst this might be the case, research, government policy and assistance from non-governmental organizations on food crop production in Zimbabwe have shown a continual inclination to maize production in semi-arid areas. However, maize is regarded as a high risk crop in these regions. The main objective of the study was to investigate major factors affecting smallholder farmers in semi-arid areas, from increased production of small grains, specifically sorghum and finger millet. The study was conducted in two rural districts of Masvingo and Gutu, which lie in natural region IV in Masvingo Province. The questionnaire was used as the main tool of inquiry to gather data from households in selected villages within these districts. Questionnaires were administered through face-to-face interviews. The total sample size was 120. The logistic regression model was used to analyze data. The results revealed that, at the 5% level, labour, cattle ownership, farm size, age, extension, yields and access to credit significantly influence sorghum and finger millet production. These findings suggest that an adjustment in each one of the significant variables can significantly influence the probability of participation in small grain production. In view of these research findings, a policy shift that encourages increased production of finger millet and sorghum in Zimbabwe‟s semi-arid regions is proposed. It is suggested that this may increase household food security in these regions.
- Full Text:
- Date Issued: 2009
Precooling strategies for passenger vehicles
- Wachsmuth, Carsten Ulrich Harro
- Authors: Wachsmuth, Carsten Ulrich Harro
- Date: 2009
- Subjects: Automobiles -- Air conditioning , Air conditioning
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9643 , http://hdl.handle.net/10948/930 , Automobiles -- Air conditioning , Air conditioning
- Description: By ventilating the vehicle’s interior during a soak, the peak cooling load is reduced and therefore the air-conditioning needs less power. This in turn translates to a smaller air-conditioning unit which would consume less power, be lighter and more compact. This solar driven ventilation of the vehicle’s interior during a soak is defined as precooling. During this project the best precooling strategy for passenger vehicles was found by investigating and testing different precooling strategies and evaluating them according to their thermodynamic performance, their potential implementation and their influence on the required cooling performance of the airconditioning cycle. The best performances were achieved by strategies with a high air flow rate and a relatively low air inlet temperature. Two categories of precooling strategies were examined: natural convection and forced convection strategies. Openings in the vehicle’s body that fit to all strategies had to be found; with a big potential concerning their thermodynamic performance and other aspects like prevention against water penetration. The best investigated precooling strategies proved to be the one which used the design outlet as an inlet and the opening of the HVAC as an outlet. With these openings a good air flow through the whole cabin can be guaranteed. In addition to that the strategy only uses existing openings of the body which prevent against water penetration. The required installation space for this strategy already exists and can be considered for the package of next generation vehicles.
- Full Text:
- Date Issued: 2009
- Authors: Wachsmuth, Carsten Ulrich Harro
- Date: 2009
- Subjects: Automobiles -- Air conditioning , Air conditioning
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9643 , http://hdl.handle.net/10948/930 , Automobiles -- Air conditioning , Air conditioning
- Description: By ventilating the vehicle’s interior during a soak, the peak cooling load is reduced and therefore the air-conditioning needs less power. This in turn translates to a smaller air-conditioning unit which would consume less power, be lighter and more compact. This solar driven ventilation of the vehicle’s interior during a soak is defined as precooling. During this project the best precooling strategy for passenger vehicles was found by investigating and testing different precooling strategies and evaluating them according to their thermodynamic performance, their potential implementation and their influence on the required cooling performance of the airconditioning cycle. The best performances were achieved by strategies with a high air flow rate and a relatively low air inlet temperature. Two categories of precooling strategies were examined: natural convection and forced convection strategies. Openings in the vehicle’s body that fit to all strategies had to be found; with a big potential concerning their thermodynamic performance and other aspects like prevention against water penetration. The best investigated precooling strategies proved to be the one which used the design outlet as an inlet and the opening of the HVAC as an outlet. With these openings a good air flow through the whole cabin can be guaranteed. In addition to that the strategy only uses existing openings of the body which prevent against water penetration. The required installation space for this strategy already exists and can be considered for the package of next generation vehicles.
- Full Text:
- Date Issued: 2009