Using iterative learning to improve understanding during the informed consent process in a South African psychiatric genomics study
- Campbell, Megan M, Susser, Ezra, Mall, Sumaya, Mqulwana, Sibonile G, Mndini, Michael M, Ntola, Odwa A, Nagdee, Mohamed, Zingela, Zukiswa, Van Wyk, Stephanus, Stein, Dan J
- Authors: Campbell, Megan M , Susser, Ezra , Mall, Sumaya , Mqulwana, Sibonile G , Mndini, Michael M , Ntola, Odwa A , Nagdee, Mohamed , Zingela, Zukiswa , Van Wyk, Stephanus , Stein, Dan J
- Date: 2017
- Subjects: Informed consent (Medical law) , Patient education
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6114 , vital:45124 , https://doi.org/10.1371/journal.pone.0188466
- Description: Obtaining informed consent is a great challenge in global health research. There is a need for tools that can screen for and improve potential research participants’ understanding of the research study at the time of recruitment. Limited empirical research has been conducted in low and middle income countries, evaluating informed consent processes in genomics research. We sought to investigate the quality of informed consent obtained in a South African psychiatric genomics study. A Xhosa language version of the University of California, San Diego Brief Assessment of Capacity to Consent Questionnaire (UBACC) was used to screen for capacity to consent and improve understanding through iterative learning in a sample of 528 Xhosa people with schizophrenia and 528 controls. We address two questions: firstly, whether research participants’ understanding of the research study improved through iterative learning; and secondly, what were predictors for better understanding of the research study at the initial screening? During screening 290 (55%) cases and 172 (33%) controls scored below the 14.5 cut-off for acceptable understanding of the research study elements, however after iterative learning only 38 (7%) cases and 13 (2.5%) controls continued to score below this cut-off. Significant variables associated with increased understanding of the consent included the psychiatric nurse recruiter conducting the consent screening, higher participant level of education, and being a control. The UBACC proved an effective tool to improve understanding of research study elements during consent, for both cases and controls. The tool holds utility for complex studies such as those involving genomics, where iterative learning can be used to make significant improvements in understanding of research study elements. The UBACC may be particularly important in groups with severe mental illness and lower education levels. Study recruiters play a significant role in managing the quality of the informed consent process.
- Full Text:
- Date Issued: 2017
- Authors: Campbell, Megan M , Susser, Ezra , Mall, Sumaya , Mqulwana, Sibonile G , Mndini, Michael M , Ntola, Odwa A , Nagdee, Mohamed , Zingela, Zukiswa , Van Wyk, Stephanus , Stein, Dan J
- Date: 2017
- Subjects: Informed consent (Medical law) , Patient education
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6114 , vital:45124 , https://doi.org/10.1371/journal.pone.0188466
- Description: Obtaining informed consent is a great challenge in global health research. There is a need for tools that can screen for and improve potential research participants’ understanding of the research study at the time of recruitment. Limited empirical research has been conducted in low and middle income countries, evaluating informed consent processes in genomics research. We sought to investigate the quality of informed consent obtained in a South African psychiatric genomics study. A Xhosa language version of the University of California, San Diego Brief Assessment of Capacity to Consent Questionnaire (UBACC) was used to screen for capacity to consent and improve understanding through iterative learning in a sample of 528 Xhosa people with schizophrenia and 528 controls. We address two questions: firstly, whether research participants’ understanding of the research study improved through iterative learning; and secondly, what were predictors for better understanding of the research study at the initial screening? During screening 290 (55%) cases and 172 (33%) controls scored below the 14.5 cut-off for acceptable understanding of the research study elements, however after iterative learning only 38 (7%) cases and 13 (2.5%) controls continued to score below this cut-off. Significant variables associated with increased understanding of the consent included the psychiatric nurse recruiter conducting the consent screening, higher participant level of education, and being a control. The UBACC proved an effective tool to improve understanding of research study elements during consent, for both cases and controls. The tool holds utility for complex studies such as those involving genomics, where iterative learning can be used to make significant improvements in understanding of research study elements. The UBACC may be particularly important in groups with severe mental illness and lower education levels. Study recruiters play a significant role in managing the quality of the informed consent process.
- Full Text:
- Date Issued: 2017
A survey of South African crime fiction : critical analysis and publishing history
- Authors: Naidu, Samantha
- Date: 2017
- Language: English
- Type: Book , text
- Identifier: vital:26344 , http://hdl.handle.net/10962/53878 , https://www.isbs.com/products/9781869143558 , https://orcid.org/0000-0001-9456-8657
- Description: Is crime fiction the new 'political novel' in South Africa? Why did the apartheid censors disapprove of crime fiction more than any other genre? Crime fiction continues to be a burgeoning literary category in post-apartheid South Africa, with more new authors, titles and themes emerging every year. This book is the first comprehensive survey of South African crime fiction. It provides an overview of this phenomenally successful literary category, and places it within its wider social and historical context. The authors specialise in both literary studies and print culture, and this combination informs a critical analysis and publishing history of South African crime fiction from the nineteenth century to the present day. The book provides a literary lineage while considering different genres and sub-genres, as well as specific themes such as gender and eco-criticism. The inclusion of a detailed bibliography of crime fiction since the 1890s makes A Survey of South African Crime Fiction an indispensable teaching and study aid
- Full Text: false
- Date Issued: 2017
- Authors: Naidu, Samantha
- Date: 2017
- Language: English
- Type: Book , text
- Identifier: vital:26344 , http://hdl.handle.net/10962/53878 , https://www.isbs.com/products/9781869143558 , https://orcid.org/0000-0001-9456-8657
- Description: Is crime fiction the new 'political novel' in South Africa? Why did the apartheid censors disapprove of crime fiction more than any other genre? Crime fiction continues to be a burgeoning literary category in post-apartheid South Africa, with more new authors, titles and themes emerging every year. This book is the first comprehensive survey of South African crime fiction. It provides an overview of this phenomenally successful literary category, and places it within its wider social and historical context. The authors specialise in both literary studies and print culture, and this combination informs a critical analysis and publishing history of South African crime fiction from the nineteenth century to the present day. The book provides a literary lineage while considering different genres and sub-genres, as well as specific themes such as gender and eco-criticism. The inclusion of a detailed bibliography of crime fiction since the 1890s makes A Survey of South African Crime Fiction an indispensable teaching and study aid
- Full Text: false
- Date Issued: 2017
The photophysical studies of Pluronic F127/P123 micelle mixture system loaded with metal free and Zn 5, 10, 15, 20-tetrakis [4-(benzyloxy) phenyl] porphyrins
- Managa, Muthumuni, Ngoy, Bokolombe P, Nyokong, Tebello
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188932 , vital:44799 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.02.018"
- Description: Binary mixtures of Pluronics are studied as drug nanocarriers in this work. H2 and Zn 5,10,15,20-tetrakis[4-(benzyloxy) phenyl] porphyrin were encapsulated onto binary micelle mixture of Pluronic F127/P123. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence quantum yield for H2TBnOPP (ΦF = 0.034) was higher than that of ZnTBnOPP (ΦF = 0.023) and decreased when ZnTBnOPP or H2TBnOPP when in the presence of Pluronic F127/P123 binary mixtures. The kq values were 2.8 × 108 and 3.7 × 108 M−1 s−1, for H2TBnOPP + Pluronic F127/P123 and ZnTBnOPP + Pluronic F127/P123 in water, respectively. The binding constants (Kb) were 1.58 × 105 M−1 and 1.02 × 105 M−1 for ZnTBnOPP + Pluronic F127/P123 and H2TBnOPP + Pluronic F127/P123, respectively.
- Full Text:
- Date Issued: 2017
- Authors: Managa, Muthumuni , Ngoy, Bokolombe P , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188932 , vital:44799 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.02.018"
- Description: Binary mixtures of Pluronics are studied as drug nanocarriers in this work. H2 and Zn 5,10,15,20-tetrakis[4-(benzyloxy) phenyl] porphyrin were encapsulated onto binary micelle mixture of Pluronic F127/P123. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. The fluorescence quantum yield for H2TBnOPP (ΦF = 0.034) was higher than that of ZnTBnOPP (ΦF = 0.023) and decreased when ZnTBnOPP or H2TBnOPP when in the presence of Pluronic F127/P123 binary mixtures. The kq values were 2.8 × 108 and 3.7 × 108 M−1 s−1, for H2TBnOPP + Pluronic F127/P123 and ZnTBnOPP + Pluronic F127/P123 in water, respectively. The binding constants (Kb) were 1.58 × 105 M−1 and 1.02 × 105 M−1 for ZnTBnOPP + Pluronic F127/P123 and H2TBnOPP + Pluronic F127/P123, respectively.
- Full Text:
- Date Issued: 2017
Synthesis and biological evaluation of anti-HIV-I integrase agents
- Jesumoroti, Omobolanle Janet
- Authors: Jesumoroti, Omobolanle Janet
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59215 , vital:27479
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2017
- Authors: Jesumoroti, Omobolanle Janet
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59215 , vital:27479
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2017
Secrets, lies and redemption:
- Boshoff, Priscilla A, Prinsloo, Jeanne
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143381 , vital:38241 , DOI: 10.1080/00020184.2017.1285671
- Description: Confession is a central disciplining technology deployed in the second series of Intersexions, a popular South African TV series that seeks to change sexual and social behaviours that contribute to the risk of HIV infection. The article considers the ‘edu’ part of this edutainment programme, specifically with the nature of the lessons and with the form of ‘disciplining’ the narratives presuppose for gendered and sexual subjects. Central to this critical and constructivist exploration of the gender relationships that are validated and expurgated are Foucault’s notions of discourse and confession as a technology of self. We argue that the series presents a range of different gendered and sexual subjectivities but implicitly endorses a modern subjectivity and transformation at the level of the individual.
- Full Text:
- Date Issued: 2017
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143381 , vital:38241 , DOI: 10.1080/00020184.2017.1285671
- Description: Confession is a central disciplining technology deployed in the second series of Intersexions, a popular South African TV series that seeks to change sexual and social behaviours that contribute to the risk of HIV infection. The article considers the ‘edu’ part of this edutainment programme, specifically with the nature of the lessons and with the form of ‘disciplining’ the narratives presuppose for gendered and sexual subjects. Central to this critical and constructivist exploration of the gender relationships that are validated and expurgated are Foucault’s notions of discourse and confession as a technology of self. We argue that the series presents a range of different gendered and sexual subjectivities but implicitly endorses a modern subjectivity and transformation at the level of the individual.
- Full Text:
- Date Issued: 2017
Evidence for protandry in Polydactylus quadrifilis in the Kwanza Estuary, Angola, and its implications for local fisheries
- Butler, Edward C, Childs, Amber-Robyn, Winkler, Alexander C, Milner, Marianne V, Potts, Warren M
- Authors: Butler, Edward C , Childs, Amber-Robyn , Winkler, Alexander C , Milner, Marianne V , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124451 , vital:35614 , https://doi.10.1007/s10641-017-0699-6
- Description: A total of 141 Polydactylus quadrifilis were sampled from the Kwanza Estuary in Angola ranging in size from 436 to 1360 mm fork-length (FL). Of these, 124 were male, six intersex and 11 female. Female fish were significantly longer (mm, FL) and heavier (kg) than males and had significantly higher gonadosomatic indices (GSI’s) than those of males and intersex fish. Transitional (intersex) gonads were delimited, with testicular and ovarian regions separated by connective tissue. The first signs of ovarian tissue appeared on the outer ventral surface of the gonad. A second layer of ovarian tissue was first noticeable at either end of the initial ovarian region and developed back towards the centre of the ventral wall to form a luminal space. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. A loss of male function was noted with increased ovarian prevalence. Based on this evidence it is suggested that P. quadrifilis in the Kwanza Estuary are protandrous. Owing to the reliance of P. quadrifilis on large highly fecund females for egg production, it is likely that they will be sensitive to fishing practices that target larger individuals within the population.
- Full Text:
- Date Issued: 2018
- Authors: Butler, Edward C , Childs, Amber-Robyn , Winkler, Alexander C , Milner, Marianne V , Potts, Warren M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124451 , vital:35614 , https://doi.10.1007/s10641-017-0699-6
- Description: A total of 141 Polydactylus quadrifilis were sampled from the Kwanza Estuary in Angola ranging in size from 436 to 1360 mm fork-length (FL). Of these, 124 were male, six intersex and 11 female. Female fish were significantly longer (mm, FL) and heavier (kg) than males and had significantly higher gonadosomatic indices (GSI’s) than those of males and intersex fish. Transitional (intersex) gonads were delimited, with testicular and ovarian regions separated by connective tissue. The first signs of ovarian tissue appeared on the outer ventral surface of the gonad. A second layer of ovarian tissue was first noticeable at either end of the initial ovarian region and developed back towards the centre of the ventral wall to form a luminal space. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. A loss of male function was noted with increased ovarian prevalence. Based on this evidence it is suggested that P. quadrifilis in the Kwanza Estuary are protandrous. Owing to the reliance of P. quadrifilis on large highly fecund females for egg production, it is likely that they will be sensitive to fishing practices that target larger individuals within the population.
- Full Text:
- Date Issued: 2018
Ngomso 'special school': contestations of morality and education in the Eastern Cape
- Authors: Pattenden, Oliver
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/65200 , vital:28704
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
- Authors: Pattenden, Oliver
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/65200 , vital:28704
- Description: Expected release date-May 2019
- Full Text:
- Date Issued: 2017
Reimag [in] ing the village as a portrait of a nation-state in Uganda:
- Authors: Kakande, Angelo
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145642 , vital:38454 , https://doi.org/10.1162/AFAR_a_00343
- Description: In this article I reexamine the ways in which certain contemporary artists based in Uganda problematize the narrative that the ruling National Resistance Movement (the NRM) party is the party of the rural poor (Cheeseman, Lynch, and Willis 2016) in their work while using it as a metaphor to inform their visual expression. I focus on the contest between tradition (imagined as a village) and modernity (imagined as a modern state), as well as the dilemma such a contest causes for a contemporary artist. Cornelius Adepegba (1995) argues that this dilemma influenced the African novel. Agreeing with Adepegba, Freeborn Odiboh (2009) observes that the same dilemma has shaped African visual artists, such as Abayomi Barber, and formal art education institutions like the Barber School in Nigeria; Odiboh then assesses the historical context in which this dilemma evolved as African nationalists struggled to forge postcolonial states based on a national consciousness amid competing ethnic, religious, and ideological interests.
- Full Text:
- Date Issued: 2017
- Authors: Kakande, Angelo
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145642 , vital:38454 , https://doi.org/10.1162/AFAR_a_00343
- Description: In this article I reexamine the ways in which certain contemporary artists based in Uganda problematize the narrative that the ruling National Resistance Movement (the NRM) party is the party of the rural poor (Cheeseman, Lynch, and Willis 2016) in their work while using it as a metaphor to inform their visual expression. I focus on the contest between tradition (imagined as a village) and modernity (imagined as a modern state), as well as the dilemma such a contest causes for a contemporary artist. Cornelius Adepegba (1995) argues that this dilemma influenced the African novel. Agreeing with Adepegba, Freeborn Odiboh (2009) observes that the same dilemma has shaped African visual artists, such as Abayomi Barber, and formal art education institutions like the Barber School in Nigeria; Odiboh then assesses the historical context in which this dilemma evolved as African nationalists struggled to forge postcolonial states based on a national consciousness amid competing ethnic, religious, and ideological interests.
- Full Text:
- Date Issued: 2017
Synthesis and photophysical studies of asymmetric zinc phthalocyanine–magnetic nanoparticle conjugates
- Matlou, Gauta G, Kobayashi, Nagao, Kimura, Mutsumi, Nyokong, Tebello
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232895 , vital:50036 , xlink:href="https://doi.org/10.1039/C7NJ01716B"
- Description: This work reports on the synthesis and amide bond linkage of carboxylic acid functionalized asymmetric zinc phthalocyanine (ZnPc) complexes to amino magnetic nanoparticles (AMNPs). The work further compares the photophysical and photochemical parameters of the Pc complexes alone with those linked to form ZnPc–AMNPs with further relation to the type of the spacer between the Pc and the AMNPs. Infrared spectroscopy confirmed the presence of the amide bond formed between the Pc complexes and the AMNPs. The triplet quantum yields ranged from 0.62 to 0.87. However, low singlet oxygen quantum yields were obtained due to competing pathways and the insufficient energy transfer from the excited triplet state of the ZnPc molecules to the molecular oxygen.
- Full Text:
- Date Issued: 2017
- Authors: Matlou, Gauta G , Kobayashi, Nagao , Kimura, Mutsumi , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232895 , vital:50036 , xlink:href="https://doi.org/10.1039/C7NJ01716B"
- Description: This work reports on the synthesis and amide bond linkage of carboxylic acid functionalized asymmetric zinc phthalocyanine (ZnPc) complexes to amino magnetic nanoparticles (AMNPs). The work further compares the photophysical and photochemical parameters of the Pc complexes alone with those linked to form ZnPc–AMNPs with further relation to the type of the spacer between the Pc and the AMNPs. Infrared spectroscopy confirmed the presence of the amide bond formed between the Pc complexes and the AMNPs. The triplet quantum yields ranged from 0.62 to 0.87. However, low singlet oxygen quantum yields were obtained due to competing pathways and the insufficient energy transfer from the excited triplet state of the ZnPc molecules to the molecular oxygen.
- Full Text:
- Date Issued: 2017
Fluorescence behaviour of supramolecular hybrids containing graphene quantum dots and pyrene-derivatized phthalocyanines and porphyrins
- Achadu, Ojodomo John, Managa, Muthumuni, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Managa, Muthumuni , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188953 , vital:44801 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.10.029"
- Description: Novel pyrene-derivatized zinc and cobalt phthalocyanines (Pcs) and porphyrins (Ps) were immobilized on graphene quantum dots (GQDs) to form GQDs-Pcs and GQDs-Ps supramolecular hybrids via the π–π stacking interaction method. Spectroscopic evidence shows that the resultant hybrids were stable owing to the strong π–π stacking interaction between the GQDs and the respective Pcs and Ps, thus leading to the fabrication of interesting and functional supramolecular hybrids by taking advantage of the delocalized π electron systems of GQDs and the macrocycles. The conjugates showed increased fluorescence quantum yields for the Pcs/Ps, but decreased values for the GQDs in the conjugates. These novel hybrid materials could potentially be deployed for studies in both fundamental and applied perspectives due to the synergistic contributions resulting from the combination of their excellent electronic and optical properties.
- Full Text:
- Date Issued: 2017
- Authors: Achadu, Ojodomo John , Managa, Muthumuni , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188953 , vital:44801 , xlink:href="https://doi.org/10.1016/j.jphotochem.2016.10.029"
- Description: Novel pyrene-derivatized zinc and cobalt phthalocyanines (Pcs) and porphyrins (Ps) were immobilized on graphene quantum dots (GQDs) to form GQDs-Pcs and GQDs-Ps supramolecular hybrids via the π–π stacking interaction method. Spectroscopic evidence shows that the resultant hybrids were stable owing to the strong π–π stacking interaction between the GQDs and the respective Pcs and Ps, thus leading to the fabrication of interesting and functional supramolecular hybrids by taking advantage of the delocalized π electron systems of GQDs and the macrocycles. The conjugates showed increased fluorescence quantum yields for the Pcs/Ps, but decreased values for the GQDs in the conjugates. These novel hybrid materials could potentially be deployed for studies in both fundamental and applied perspectives due to the synergistic contributions resulting from the combination of their excellent electronic and optical properties.
- Full Text:
- Date Issued: 2017
Justin Davy of Burning Museum: an interview
- Authors: Dantas, Nancy
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147070 , vital:38590 , https://www.on-curating.org/issue-32-reader/justin-davy-of-the-burning-museum.html#.Xs0mCmgzbIU
- Description: The Burning Museum is an arts collective based in Cape Town, South Africa. This interview is the result of a three-part Skype conversation between Justin Davy of the Burning Museum and Nancy Dantas, an independent curator and researcher with an interest in recovering the neglected and overlooked exhibition histories and practices of the south.
- Full Text:
- Date Issued: 2017
- Authors: Dantas, Nancy
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147070 , vital:38590 , https://www.on-curating.org/issue-32-reader/justin-davy-of-the-burning-museum.html#.Xs0mCmgzbIU
- Description: The Burning Museum is an arts collective based in Cape Town, South Africa. This interview is the result of a three-part Skype conversation between Justin Davy of the Burning Museum and Nancy Dantas, an independent curator and researcher with an interest in recovering the neglected and overlooked exhibition histories and practices of the south.
- Full Text:
- Date Issued: 2017
Interrogating citizen journalism practices: a case study of Rhodes University’s Lindaba Ziyafika Project
- Nyathi, Sihle, Garman, Anthea
- Authors: Nyathi, Sihle , Garman, Anthea
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158915 , vital:40240 , https://doi.org/10.1080/23743670.2016.1259740
- Description: Several scholars have noted that citizen journalism in the West is essentially an online phenomenon, driven by the affordability of Internet technologies. In Africa, projects such as Ushahidi in Kenya have been enabled by platforms such as cell phones and social networks. Voices of Africa, based in southern Africa, publishes on the web only. Publishing on the Internet presumes a citizenry which is relatively well educated; has familiarity with, and access to, new media as a form of social communication; and is confident in their right to participate in newly developed public spheres – particularly those online.
- Full Text:
- Date Issued: 2017
- Authors: Nyathi, Sihle , Garman, Anthea
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158915 , vital:40240 , https://doi.org/10.1080/23743670.2016.1259740
- Description: Several scholars have noted that citizen journalism in the West is essentially an online phenomenon, driven by the affordability of Internet technologies. In Africa, projects such as Ushahidi in Kenya have been enabled by platforms such as cell phones and social networks. Voices of Africa, based in southern Africa, publishes on the web only. Publishing on the Internet presumes a citizenry which is relatively well educated; has familiarity with, and access to, new media as a form of social communication; and is confident in their right to participate in newly developed public spheres – particularly those online.
- Full Text:
- Date Issued: 2017
Stochastic models in finance
- Authors: Mazengera, Hassan
- Date: 2017
- Subjects: Finance -- Mathematical models , C++ (Computer program language) , GARCH model , Lebesgue-Radon-Nikodym theorems , Radon measures , Stochastic models , Stochastic processes , Stochastic processes -- Computer programs , Martingales (Mathematics) , Pricing -- Mathematical models
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/162724 , vital:40976
- Description: Stochastic models for pricing financial securities are developed. First, we consider the Black Scholes model, which is a classic example of a complete market model and finally focus on Lévy driven models. Jumps may render the market incomplete and are induced in a model by inclusion of a Poisson process. Lévy driven models are more realistic in modelling of asset price dynamics than the Black Scholes model. Martingales are central in pricing, especially of derivatives and we give them the desired attention in the context of pricing. There are an increasing number of important pricing models where analytical solutions are not available hence computational methods come in handy, see Broadie and Glasserman (1997). It is also important to note that computational methods are also applicable to models with analytical solutions. We computationally value selected stochastic financial models using C++. Computational methods are also used to value or price complex financial instruments such as path dependent derivatives. This pricing procedure is applied in the computational valuation of a stochastic (revenue based) loan contract. Derivatives with simple pay of functions and models with analytical solutions are considered for illustrative purposes. The Black-Scholes P.D.E is complex to solve analytically and finite difference methods are widely used. Explicit finite difference scheme is considered in this thesis for computational valuation of derivatives that are modelled by the Black-Scholes P.D.E. Stochastic modelling of asset prices is important for the valuation of derivatives: Gaussian, exponential and gamma variates are simulated for the valuation purposes.
- Full Text:
- Date Issued: 2017
- Authors: Mazengera, Hassan
- Date: 2017
- Subjects: Finance -- Mathematical models , C++ (Computer program language) , GARCH model , Lebesgue-Radon-Nikodym theorems , Radon measures , Stochastic models , Stochastic processes , Stochastic processes -- Computer programs , Martingales (Mathematics) , Pricing -- Mathematical models
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/162724 , vital:40976
- Description: Stochastic models for pricing financial securities are developed. First, we consider the Black Scholes model, which is a classic example of a complete market model and finally focus on Lévy driven models. Jumps may render the market incomplete and are induced in a model by inclusion of a Poisson process. Lévy driven models are more realistic in modelling of asset price dynamics than the Black Scholes model. Martingales are central in pricing, especially of derivatives and we give them the desired attention in the context of pricing. There are an increasing number of important pricing models where analytical solutions are not available hence computational methods come in handy, see Broadie and Glasserman (1997). It is also important to note that computational methods are also applicable to models with analytical solutions. We computationally value selected stochastic financial models using C++. Computational methods are also used to value or price complex financial instruments such as path dependent derivatives. This pricing procedure is applied in the computational valuation of a stochastic (revenue based) loan contract. Derivatives with simple pay of functions and models with analytical solutions are considered for illustrative purposes. The Black-Scholes P.D.E is complex to solve analytically and finite difference methods are widely used. Explicit finite difference scheme is considered in this thesis for computational valuation of derivatives that are modelled by the Black-Scholes P.D.E. Stochastic modelling of asset prices is important for the valuation of derivatives: Gaussian, exponential and gamma variates are simulated for the valuation purposes.
- Full Text:
- Date Issued: 2017
Improved nonlinear optical behaviour of ball type indium (III) phthalocyanine linked to glutathione capped nanoparticles
- Nwaji, Njemuwa, Oluwole, David O, Mack, John, Louzada, Marcel, Khene, Samson M, Britton, Jonathan, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
- Authors: Nwaji, Njemuwa , Oluwole, David O , Mack, John , Louzada, Marcel , Khene, Samson M , Britton, Jonathan , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239654 , vital:50752 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.01.066"
- Description: The synthesis of ball–type indium phthalocyanine (complex 4) and its covalent attachment to glutathione (GSH–) capped (Ag, Au, CdTeSe, CdTeSe/ZnO) nanoparticles are reported in this work. Furthermore, their photophysical and nonlinear optical behaviour were investigated. We observed a decrease in the fluorescence quantum yield with corresponding increase in the triplet quantum yield of the nanoconjugates in comparison to complex 4 alone. The reverse saturable absorption was found to be dependent on excited state absorption. The optical limiting threshold ranges from 0.40–0.78 (J/cm2). The nanoconjugate of the complex 4 with GSH–CdTeSe/ZnO (QD1) accounted for the most improved triplet state parameters and nonlinear optical behaviour in comparison to complex 4 and the other nanoconjugates studied in this work.
- Full Text:
- Date Issued: 2017
Assessing the potential role of microorganisms in the production of seedlings for the restoration of Albany Thicket
- Authors: Mpama, Nelisa
- Date: 2017
- Subjects: Vesicular-arbuscular mycorrhizas , Rhizobacteria , Restoration ecology South Africa Albany , Microorganisms
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64555 , vital:28558
- Description: The role of microorganisms in restoration of the Albany Thicket has not been well documented, although the benefits to plants of these various interactions has been well documented. Microorganisms are chief ecological engineers and assist in resolving environmental problems and act to restore degraded ecosystem function by forming mutual relationships with the roots of the plants. The aim of this study was to assess the potential of microorganisms for the improved biomass production of selected woody and succulent seedlings used in mesic thicket restoration. Three tree species were selected for propagation in this study namely; Mystroxylon aethiopicum Scutia myrtina and Aloe ferox. Soil samples were collected from a degraded and intact thicket site from Bathurst, South Africa. Soils were evaluated for number of arbuscular mycorrhizal (AM) spores, mycorrhizal infectivity potential and nutrient availability both before and after seedling propagation. Pasteurized soil from the degraded site was used in a pot trial. Ten replicates seedling for plant species were planted and subjected to four treatments which included inoculation with AM fungi and the rhizobacterium, Enterobacter sp., alone and in combination; the fourth treatment was an un-inouclated control. Plant growth parameters were recorded at regular intervals where appropriate and seedlings were harvested after 24 weeks for biomass measurements and AM colonisation assessments. Although generally low (< 1 spore per gram) the density of AM fungal spores was significantly higher in soils from the intact site when compared with soils from the degraded site. The mycorrhizal potential of the soils was however not significantly different. Mystroxylon aethiopicum seedling shoot height, canopy diameter and shoot biomass showed a significant increase when inoculated with AM fungi while S. myrtina seedlings showed increased shoot height when inoculated with both AM fungi and Enterobacter sp. Aloe ferox seedlings did not respond to microbial inoculation. The concentration of soil P and Na increased in treatments with Enterobacter sp. alone and in combination with AM fungi. Mystroxylon aethiopicum and S. myrtina seedlings showed a dependency on microbial inoculants indicating the importance of inoculation in the nursery before planting out into the field. Overall AM fungal inoculants applied to seedlings can be used to compensate for nutrient deficiency in soils. Although the Enterobacter isolate used was known to have various plant growth promoting capabilities. It is recommended that other rhizobacterial isolates be investigated. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2017
- Full Text:
- Date Issued: 2017
- Authors: Mpama, Nelisa
- Date: 2017
- Subjects: Vesicular-arbuscular mycorrhizas , Rhizobacteria , Restoration ecology South Africa Albany , Microorganisms
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64555 , vital:28558
- Description: The role of microorganisms in restoration of the Albany Thicket has not been well documented, although the benefits to plants of these various interactions has been well documented. Microorganisms are chief ecological engineers and assist in resolving environmental problems and act to restore degraded ecosystem function by forming mutual relationships with the roots of the plants. The aim of this study was to assess the potential of microorganisms for the improved biomass production of selected woody and succulent seedlings used in mesic thicket restoration. Three tree species were selected for propagation in this study namely; Mystroxylon aethiopicum Scutia myrtina and Aloe ferox. Soil samples were collected from a degraded and intact thicket site from Bathurst, South Africa. Soils were evaluated for number of arbuscular mycorrhizal (AM) spores, mycorrhizal infectivity potential and nutrient availability both before and after seedling propagation. Pasteurized soil from the degraded site was used in a pot trial. Ten replicates seedling for plant species were planted and subjected to four treatments which included inoculation with AM fungi and the rhizobacterium, Enterobacter sp., alone and in combination; the fourth treatment was an un-inouclated control. Plant growth parameters were recorded at regular intervals where appropriate and seedlings were harvested after 24 weeks for biomass measurements and AM colonisation assessments. Although generally low (< 1 spore per gram) the density of AM fungal spores was significantly higher in soils from the intact site when compared with soils from the degraded site. The mycorrhizal potential of the soils was however not significantly different. Mystroxylon aethiopicum seedling shoot height, canopy diameter and shoot biomass showed a significant increase when inoculated with AM fungi while S. myrtina seedlings showed increased shoot height when inoculated with both AM fungi and Enterobacter sp. Aloe ferox seedlings did not respond to microbial inoculation. The concentration of soil P and Na increased in treatments with Enterobacter sp. alone and in combination with AM fungi. Mystroxylon aethiopicum and S. myrtina seedlings showed a dependency on microbial inoculants indicating the importance of inoculation in the nursery before planting out into the field. Overall AM fungal inoculants applied to seedlings can be used to compensate for nutrient deficiency in soils. Although the Enterobacter isolate used was known to have various plant growth promoting capabilities. It is recommended that other rhizobacterial isolates be investigated. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2017
- Full Text:
- Date Issued: 2017
Effects of symmetry and the number of positive charges on the photocatalytic activity of indium phthalocyanines when embedded in electrospun fibers
- Chakona, Gamuchirai, Nyokong, Tebello
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
- Authors: Chakona, Gamuchirai , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188304 , vital:44743 , xlink:href="https://doi.org/10.1016/j.ica.2016.12.025"
- Description: Photooxidations of bisphenol A and 4-chlorophenol were carried out in this study using two asymmetric indium(III) phthalocyanines photosensitizers: the first consisting of one quaternized 4-pyridyloxyl and no other substituents (complex 1) and the second containing three quaternized 4-pyridylsulfanyl units and one aminophenoxy (complex 3). The asymmetry of complex 3 is additionally caused by the presence of two linking atoms (O and S). The symmetrically substituted indium(III) phthalocyanine containing four quaternized 4-pyridyloxyl units (complex 2) was also studied. The complexes were embedded in electrospun polystyrene fiber for heterogeneous photocatalytic transformation of 4-chlorophenol and bisphenol A. When immobilized on electrospun fibers, complexes 1, 2 and 3 gave singlet oxygen values of 0.31, 0.39 and 0.50 in water, respectively. Complex 3 showed the best photocatalytic behavior with observed rate constants of 2.8 × 10−3 min−1 for bisphenol A and 3.8 × 10−3 min−1 for 4-chlorophenol.
- Full Text:
- Date Issued: 2017
Factors influencing the shape of CW-OSL signal obtained by stimulation of very deep traps in carbon-doped aluminium oxide: an experimental study
- Nyirenda, Angel N, Chithambo, Makaiko L
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115493 , vital:34149 , https://doi.org/10.1016/j.jlumin.2017.07.016
- Description: The optically stimulated luminescence from carbon-doped aluminium oxide (α-Al2O3:C) displays a peak with time under certain measurement conditions. In this paper, we present factors that influence the peak-like shape of continuous-wave optically stimulated luminescence (CW-OSL) signal. The report is based on the experimental study of OSL signals obtained by stimulation of very deep traps in α-Al2O3:C. Methods exploiting post-irradiation annealing, variable dose and temperature dependent OSL measurements were used in the investigation. It is found that the rising part of the CW-OSL peak is obtained when the rate of retrapping at the most optically active trap (main trap) exceeds the rate of direct radiative recombination following optical release of charges from all optically active traps. This is possible if, during optical stimulation, the primary trap responsible for OSL i.e. the main trap, is substantially unoccupied and the very deep, donor traps are substantially filled up. The rate of charge retrapping itself is deduced to depend on the occupancy of the acceptor traps i.e. shallow, main and secondary traps; concentration of charge carriers in the very deep, donor traps; the post-irradiation annealing temperature and the temperature at which the OSL is measured.
- Full Text: false
- Date Issued: 2017
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115493 , vital:34149 , https://doi.org/10.1016/j.jlumin.2017.07.016
- Description: The optically stimulated luminescence from carbon-doped aluminium oxide (α-Al2O3:C) displays a peak with time under certain measurement conditions. In this paper, we present factors that influence the peak-like shape of continuous-wave optically stimulated luminescence (CW-OSL) signal. The report is based on the experimental study of OSL signals obtained by stimulation of very deep traps in α-Al2O3:C. Methods exploiting post-irradiation annealing, variable dose and temperature dependent OSL measurements were used in the investigation. It is found that the rising part of the CW-OSL peak is obtained when the rate of retrapping at the most optically active trap (main trap) exceeds the rate of direct radiative recombination following optical release of charges from all optically active traps. This is possible if, during optical stimulation, the primary trap responsible for OSL i.e. the main trap, is substantially unoccupied and the very deep, donor traps are substantially filled up. The rate of charge retrapping itself is deduced to depend on the occupancy of the acceptor traps i.e. shallow, main and secondary traps; concentration of charge carriers in the very deep, donor traps; the post-irradiation annealing temperature and the temperature at which the OSL is measured.
- Full Text: false
- Date Issued: 2017
Chemical composition of leaf essential oils of Lantana camara varieties in South Africa and their effect on the behavioural preference of Falconia intermedia
- Authors: Ngxande-Koza, Samella W
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4877 , vital:20739
- Description: Lantana camara L. (Verbenaceae) is one the most problematic invaders in South Africa invading forest edges, sand dunes, and shorelines by forming impenetrable thickets. Lantana camara invasions degrade natural biodiversity, reduce the value of land and consequently it has been a target for biological control, over the last 50 years in South Africa. Studies that have reported on chemical profile of Lantana camara have been conducted around the world but not in South Africa. Hence, the first aim of the current study was to identify the chemical baseline of L. camara varieties in the Eastern Cape, South Africa. Recent studies have shown that feeding by one of the agents released against L. camara, Falconia intermedia (Distant) (Hemiptera: Miridae), induces anti-herbivory response through increased leaf toughness and trichome density. A preliminary study conducted also reported the production of volatile chemicals by one variety, Whitney Farm, due to feeding by the mirids. Therefore, the second aim was to determine the induced changes in chemical compounds of L. camara varieties after feeding by F. intermedia. A third aim was to determine the effect these chemical compounds have on the behaviour of F. intermedia. To identify the chemical baseline of L. camara varieties, the essential oils of four L. camara varieties (East London, Port Alfred, Whitney Farm and Heather Glen) were analysed using gas chromatography mass spectrometry (GC-MS) and that resulted to the identification of 163 constitutive and 75 induced chemicals across the varieties tested. Lantana camara varieties showed different chemical classes but were highly dominated by terpenes. A great variation in the number of constitutive chemical compounds was found in all the varieties. There were 56 constitutive chemical compounds in the Whitney Farm variety, 41 in the East London variety, 36 in the Heather Glen variety and 30 in the Port Alfred variety. The Whitney Farm variety had the highest number (22) of unique constitutive chemicals identified when compared with other varieties. This indicates the chemical distinctiveness of the Whitney Farm variety from the other varieties. In the varieties tested, there were common chemical compounds identified in constitutive and induced (discussed below) states of the plants such as caryophyllene, hexane, naphthalene, copaene and a-caryophyllene. Besides naphthalene, the majority of chemical compounds in South African L. camara varieties were similar to compounds that have been identified across the world, suggesting that they are closely related. The expression of naphthalene in these varieties may be due to changes in the chemicals expressed over evolutionary time as predicted by the Novel Weapons Hypothesis. Amongst the varieties, a great variation in chemical compounds and their concentrations was shown in the induced states of the plants. The concentration of constitutive caryophyllene ranged from (3.13 - 15.7) %, to (4.02 - 11.10) % after feeding. The concentration of constitutive hexane ranged from (6.13 - 71.19) %, to (33.3 - 75.8) % after feeding. The concentration of constitutive naphthalene ranged from (0.21 - 4.79) %, to (0.92 - 2.11) % after feeding. The concentration of constitutive copaene ranged from (0.57 - 1.57) %, to (1.20 - 2.72) %. Lastly, the concentration of constitutive a-caryophyllene ranged from (1.18 - 9.03) %, to (0.78 - 5.48) % after feeding. The changes in chemical concentrations in lantana varieties indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. To determine the effect of the identified compounds on the behaviour of F. intermedia adults, olfactometer bioassays were conducted using a Y-tube technique. A significantly higher proportion of F. intermedia were attracted to undamaged leaves over damaged leaves and purified air. Undamaged leaves attracted 52 % of F. intermedia from the East London variety, 62.5 % from the Port Alfred variety, 56 % from the Whitney Farm variety, 58 % from the Lyndhurst variety and 54.5 % from the Heather Glen variety in dual choice trials versus damaged leaves. Furthermore, a significantly higher proportion of F. intermedia were attracted to damaged leaves over purified air. Damaged leaves attracted 67 % of F. intermedia from the East London variety, 67 % from the Port Alfred variety, 65.9 % from the Whitney Farm variety, 65.3 % from the Heather Glen variety and 64.5 % from the Lyndhurst variety. Olfactometer bioassays were also conducted using purified standard compounds of four chemical compounds identified from essential oils, hexane was used as a positive control as it is reported to be an insect attractant in literature. Hexane was highly attractive to the mirids compared to three standard compounds caryophyllene, caryophyllene oxide and naphthalene at the rate of 80 %, 73 % and 80 %, respectively. The standard compounds tested against F. intermedia are major compounds contained by L. camara varieties and they have proven to have a repellent effect. This may indicate that after feeding by F. intermedia, the major compounds expressed by the plant varieties repel F. intermedia contributing to the invasiveness of this weed. The increased expression of hexane and caryophyllene after feeding may also indicate increased attraction to some insects, opening up the potential for third trophic level interactions in varieties where this is the case. This is the first study on the chemical composition of essential oils of L. camara in South Africa. Therefore, we recommend that where appropriate chemical profile studies of the invasive alien plants should be considered during host specificity testing, and the vital role of chemical compounds on agent-weed interactions must be taken into consideration with other factors before and after the biological control agents are released.
- Full Text:
- Date Issued: 2017
- Authors: Ngxande-Koza, Samella W
- Date: 2017
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4877 , vital:20739
- Description: Lantana camara L. (Verbenaceae) is one the most problematic invaders in South Africa invading forest edges, sand dunes, and shorelines by forming impenetrable thickets. Lantana camara invasions degrade natural biodiversity, reduce the value of land and consequently it has been a target for biological control, over the last 50 years in South Africa. Studies that have reported on chemical profile of Lantana camara have been conducted around the world but not in South Africa. Hence, the first aim of the current study was to identify the chemical baseline of L. camara varieties in the Eastern Cape, South Africa. Recent studies have shown that feeding by one of the agents released against L. camara, Falconia intermedia (Distant) (Hemiptera: Miridae), induces anti-herbivory response through increased leaf toughness and trichome density. A preliminary study conducted also reported the production of volatile chemicals by one variety, Whitney Farm, due to feeding by the mirids. Therefore, the second aim was to determine the induced changes in chemical compounds of L. camara varieties after feeding by F. intermedia. A third aim was to determine the effect these chemical compounds have on the behaviour of F. intermedia. To identify the chemical baseline of L. camara varieties, the essential oils of four L. camara varieties (East London, Port Alfred, Whitney Farm and Heather Glen) were analysed using gas chromatography mass spectrometry (GC-MS) and that resulted to the identification of 163 constitutive and 75 induced chemicals across the varieties tested. Lantana camara varieties showed different chemical classes but were highly dominated by terpenes. A great variation in the number of constitutive chemical compounds was found in all the varieties. There were 56 constitutive chemical compounds in the Whitney Farm variety, 41 in the East London variety, 36 in the Heather Glen variety and 30 in the Port Alfred variety. The Whitney Farm variety had the highest number (22) of unique constitutive chemicals identified when compared with other varieties. This indicates the chemical distinctiveness of the Whitney Farm variety from the other varieties. In the varieties tested, there were common chemical compounds identified in constitutive and induced (discussed below) states of the plants such as caryophyllene, hexane, naphthalene, copaene and a-caryophyllene. Besides naphthalene, the majority of chemical compounds in South African L. camara varieties were similar to compounds that have been identified across the world, suggesting that they are closely related. The expression of naphthalene in these varieties may be due to changes in the chemicals expressed over evolutionary time as predicted by the Novel Weapons Hypothesis. Amongst the varieties, a great variation in chemical compounds and their concentrations was shown in the induced states of the plants. The concentration of constitutive caryophyllene ranged from (3.13 - 15.7) %, to (4.02 - 11.10) % after feeding. The concentration of constitutive hexane ranged from (6.13 - 71.19) %, to (33.3 - 75.8) % after feeding. The concentration of constitutive naphthalene ranged from (0.21 - 4.79) %, to (0.92 - 2.11) % after feeding. The concentration of constitutive copaene ranged from (0.57 - 1.57) %, to (1.20 - 2.72) %. Lastly, the concentration of constitutive a-caryophyllene ranged from (1.18 - 9.03) %, to (0.78 - 5.48) % after feeding. The changes in chemical concentrations in lantana varieties indicated that feeding by the mirid on L. camara varieties causes an induction by either reducing or increasing the chemical concentrations. To determine the effect of the identified compounds on the behaviour of F. intermedia adults, olfactometer bioassays were conducted using a Y-tube technique. A significantly higher proportion of F. intermedia were attracted to undamaged leaves over damaged leaves and purified air. Undamaged leaves attracted 52 % of F. intermedia from the East London variety, 62.5 % from the Port Alfred variety, 56 % from the Whitney Farm variety, 58 % from the Lyndhurst variety and 54.5 % from the Heather Glen variety in dual choice trials versus damaged leaves. Furthermore, a significantly higher proportion of F. intermedia were attracted to damaged leaves over purified air. Damaged leaves attracted 67 % of F. intermedia from the East London variety, 67 % from the Port Alfred variety, 65.9 % from the Whitney Farm variety, 65.3 % from the Heather Glen variety and 64.5 % from the Lyndhurst variety. Olfactometer bioassays were also conducted using purified standard compounds of four chemical compounds identified from essential oils, hexane was used as a positive control as it is reported to be an insect attractant in literature. Hexane was highly attractive to the mirids compared to three standard compounds caryophyllene, caryophyllene oxide and naphthalene at the rate of 80 %, 73 % and 80 %, respectively. The standard compounds tested against F. intermedia are major compounds contained by L. camara varieties and they have proven to have a repellent effect. This may indicate that after feeding by F. intermedia, the major compounds expressed by the plant varieties repel F. intermedia contributing to the invasiveness of this weed. The increased expression of hexane and caryophyllene after feeding may also indicate increased attraction to some insects, opening up the potential for third trophic level interactions in varieties where this is the case. This is the first study on the chemical composition of essential oils of L. camara in South Africa. Therefore, we recommend that where appropriate chemical profile studies of the invasive alien plants should be considered during host specificity testing, and the vital role of chemical compounds on agent-weed interactions must be taken into consideration with other factors before and after the biological control agents are released.
- Full Text:
- Date Issued: 2017
An analysis of flood activity over the past century based on the sedimentary deposits in the Mfolozi floodplain
- Authors: Mbao, Chabala
- Date: 2017
- Subjects: Floodplain morphology -- South Africa -- Mfolozi River , Floodplains -- South Africa -- Kwazulu-Natal , Sedimentation and deposition -- South Africa -- Kwazulu-Natal , Floods -- South Africa -- Kwazulu-Natal -- Measurement , Hydrology -- Research -- South Africa -- Kwazulu-Natal , Stream measurements -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/53711 , vital:26312
- Description: Floods are natural phenomena that are of widespread interest to the scientific community, particularly in the context of understanding the impact of climate change as well as changing land use patterns and the security of infrastructure such as towns and roads. In northern KwaZulu-Natal, large flood events have been a reoccurring feature over the past century. The geographical position and extent of the region means that is affected by both inland and coastal weather phenomena, each with the potential to cause large flood events. While information pertaining to large floods in the region in the form of flow data is readily available, flow data is often incomplete and limited in terms of how far back in time the records extend. The Mfolozi River floodplain itself also houses a record of flood activity in the region in the form of sedimentary deposits, which have the potential to reveal flood activity over a much longer timescale, even when monitoring of flood activity in the region was not present. Establishing a link between the hydrological and sedimentary features of floods may be useful in establishing a record of flood activity extending beyond the limits of historical records. The aim of this project was to construct a record of major flood events on the Mfolozi River floodplain over the last century and determine their source. The first objective involved establishing the history of flood events in the Mfolozi River catchment utilising hydrological data recorded throughout the catchment. Thirty nine different large floods (defined as being over 800 m3.s-1) were recorded on the floodplain over the past century. The data also highlighted differences in the extent of known coastal and inland systems (tropical cyclones and cut-off lows respectively), allowing for inferences to be made about the area of the catchment most likely affected by each event; some flood events were identified as having mostly affected the upper reaches of the catchment, while others mostly affected the lower reaches, closer to the coast. The second objective was to identify the various physical, mineralogical and geochemical features of the sediment deposited on the Mfolozi floodplain. Multiple individual flood deposits were identified in the sedimentary record, with sediment tracing analysis providing insight into the source of the deposits within the catchment; no traces of igneous or metamorphic material could be found within the sediment. The source rocks were identified as mostly quartzite, with minor shale and sandstone deposits as well. This put the source of the sediment in the upper to middle reaches of the catchment. The sedimentary analysis was combined with the hydrological records to establish a chronology of flood events extending back to the 1960's. Unfortunately, this record could not be extended further due to the limited amount of sediment collected as well the limits of readily available analytical techniques; radionuclide dating methods were unsuccessful due to the low amounts of fallout radionuclides present in the sediment. The study has however successfully established a history of flood events in the region, as well as providing a link between the hydrological and sedimentary features of flood events that could potentially be useful for current and future research.
- Full Text:
- Date Issued: 2017
- Authors: Mbao, Chabala
- Date: 2017
- Subjects: Floodplain morphology -- South Africa -- Mfolozi River , Floodplains -- South Africa -- Kwazulu-Natal , Sedimentation and deposition -- South Africa -- Kwazulu-Natal , Floods -- South Africa -- Kwazulu-Natal -- Measurement , Hydrology -- Research -- South Africa -- Kwazulu-Natal , Stream measurements -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/53711 , vital:26312
- Description: Floods are natural phenomena that are of widespread interest to the scientific community, particularly in the context of understanding the impact of climate change as well as changing land use patterns and the security of infrastructure such as towns and roads. In northern KwaZulu-Natal, large flood events have been a reoccurring feature over the past century. The geographical position and extent of the region means that is affected by both inland and coastal weather phenomena, each with the potential to cause large flood events. While information pertaining to large floods in the region in the form of flow data is readily available, flow data is often incomplete and limited in terms of how far back in time the records extend. The Mfolozi River floodplain itself also houses a record of flood activity in the region in the form of sedimentary deposits, which have the potential to reveal flood activity over a much longer timescale, even when monitoring of flood activity in the region was not present. Establishing a link between the hydrological and sedimentary features of floods may be useful in establishing a record of flood activity extending beyond the limits of historical records. The aim of this project was to construct a record of major flood events on the Mfolozi River floodplain over the last century and determine their source. The first objective involved establishing the history of flood events in the Mfolozi River catchment utilising hydrological data recorded throughout the catchment. Thirty nine different large floods (defined as being over 800 m3.s-1) were recorded on the floodplain over the past century. The data also highlighted differences in the extent of known coastal and inland systems (tropical cyclones and cut-off lows respectively), allowing for inferences to be made about the area of the catchment most likely affected by each event; some flood events were identified as having mostly affected the upper reaches of the catchment, while others mostly affected the lower reaches, closer to the coast. The second objective was to identify the various physical, mineralogical and geochemical features of the sediment deposited on the Mfolozi floodplain. Multiple individual flood deposits were identified in the sedimentary record, with sediment tracing analysis providing insight into the source of the deposits within the catchment; no traces of igneous or metamorphic material could be found within the sediment. The source rocks were identified as mostly quartzite, with minor shale and sandstone deposits as well. This put the source of the sediment in the upper to middle reaches of the catchment. The sedimentary analysis was combined with the hydrological records to establish a chronology of flood events extending back to the 1960's. Unfortunately, this record could not be extended further due to the limited amount of sediment collected as well the limits of readily available analytical techniques; radionuclide dating methods were unsuccessful due to the low amounts of fallout radionuclides present in the sediment. The study has however successfully established a history of flood events in the region, as well as providing a link between the hydrological and sedimentary features of flood events that could potentially be useful for current and future research.
- Full Text:
- Date Issued: 2017
Cosmopolitanism and the unfollowable routines and rituals in Ishtiyaq Shukri’s The Silent Minaret:
- Authors: Dass, Minesh
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142531 , vital:38088 , DOI: 10.1080/02564718.2017.1290382
- Description: This article explores how Ishtiyaq Shukri’s The Silent Minaret critiques the limited and severely uneven forms of hospitality that characterise post-9/11 Britain. It also examines how the text gestures towards the possibility of a non-violent, inclusive cosmopolitanism. The piece begins by relating recent debates surrounding the “War on Terror”, as well as Britain’s decision to leave the European Union to the novel’s major concerns. It then turns to the novel, and summarises incidents in which the principal character, Issa Shamshuddin, is traumatised and harmed by the Islamophobia and anti-immigration policies evident in the London portrayed in the text. Next, it turns to an analysis of the strange and irreproducible rituals of Issa’s neighbour, Frances. The article concludes that that these unfollowable rituals posit how a truly cosmopolitan society would function.
- Full Text:
- Date Issued: 2017
- Authors: Dass, Minesh
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/142531 , vital:38088 , DOI: 10.1080/02564718.2017.1290382
- Description: This article explores how Ishtiyaq Shukri’s The Silent Minaret critiques the limited and severely uneven forms of hospitality that characterise post-9/11 Britain. It also examines how the text gestures towards the possibility of a non-violent, inclusive cosmopolitanism. The piece begins by relating recent debates surrounding the “War on Terror”, as well as Britain’s decision to leave the European Union to the novel’s major concerns. It then turns to the novel, and summarises incidents in which the principal character, Issa Shamshuddin, is traumatised and harmed by the Islamophobia and anti-immigration policies evident in the London portrayed in the text. Next, it turns to an analysis of the strange and irreproducible rituals of Issa’s neighbour, Frances. The article concludes that that these unfollowable rituals posit how a truly cosmopolitan society would function.
- Full Text:
- Date Issued: 2017