Formulation and evaluation of captopril loaded polymethacrylate and hydroxypropyl methycellulose microcapsules
- Khamanga, Sandile Maswazi Malungelo
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
Framework for local government to implement integrated water resource management linked to water service delivery
- Haigh, Eliria H, Fox, Helen E, Davies-Coleman, Heather D
- Authors: Haigh, Eliria H , Fox, Helen E , Davies-Coleman, Heather D
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7097 , http://hdl.handle.net/10962/d1012440
- Description: The Water Services Act (No. 8 of 1997) of South Africa states that water service delivery is the responsibility of local government as Water Services Authorities. The principal legal responsibility is to complete a Water Services Development Plan (WSDP) every 5 years with annual review. The WSDP encapsulates all the responsibilities and tasks required in water service delivery. However, it does not spell out local government’s role in water resource protection or its responsibilities as far as integrated water resource management is concerned. It is well known in South Africa that there is a challenging level of inadequate capacity in technical and administrative skills in local government to adequately fulfil water service delivery. This paper highlights the consequences of this incapacity for municipalities and their difficulties in fulfilling their responsibilities as service providers. A framework is provided within which improvements can be brought about, with guidance on how to engage in the practice of integrated water resource management (IWRM) in the context of the legal framework for water services. The additional tasks and changes required to practise IWRM are set in the context of the WSDP. The framework provides a guide for a municipality to first accomplish an adequate WSDP, and then to gradually implement IWRM. A discussion on the skills needed to accomplish, firstly, a comprehensive WSDP, and secondly, IWRM, is included.
- Full Text:
- Authors: Haigh, Eliria H , Fox, Helen E , Davies-Coleman, Heather D
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7097 , http://hdl.handle.net/10962/d1012440
- Description: The Water Services Act (No. 8 of 1997) of South Africa states that water service delivery is the responsibility of local government as Water Services Authorities. The principal legal responsibility is to complete a Water Services Development Plan (WSDP) every 5 years with annual review. The WSDP encapsulates all the responsibilities and tasks required in water service delivery. However, it does not spell out local government’s role in water resource protection or its responsibilities as far as integrated water resource management is concerned. It is well known in South Africa that there is a challenging level of inadequate capacity in technical and administrative skills in local government to adequately fulfil water service delivery. This paper highlights the consequences of this incapacity for municipalities and their difficulties in fulfilling their responsibilities as service providers. A framework is provided within which improvements can be brought about, with guidance on how to engage in the practice of integrated water resource management (IWRM) in the context of the legal framework for water services. The additional tasks and changes required to practise IWRM are set in the context of the WSDP. The framework provides a guide for a municipality to first accomplish an adequate WSDP, and then to gradually implement IWRM. A discussion on the skills needed to accomplish, firstly, a comprehensive WSDP, and secondly, IWRM, is included.
- Full Text:
Framing the foreigner : a close reading of readers' comments on Thought leader blogs on xenophobia published between May and June, 2008
- Authors: Mwilu, Lwanga Racheal
- Date: 2010
- Subjects: Xenophobia in mass media -- South Africa Immigrants in mass media -- South Africa Mail & Guardian Thought leader Blogs -- South Africa Online hate speech -- South Africa Freedom of expression -- South Africa Online journalism -- Moral and ethical aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3472 , http://hdl.handle.net/10962/d1002927
- Description: This study was conducted to identify and analyse Mail and Guardian Online moderation outputs which contradicted the platform‟s own stated policy on hate speech and other forms of problematic speech. The moderation outputs considered were a battery of readers‟ comments that were posted in response to Thought Leader blogs on xenophobia published between May and June, 2008. This was the same period a series of xenophobic attacks was taking place in some parts of South Africa, leaving an estimated 62 people dead, more than 30,000 displaced, and countless victims injured and robbed of their property. The attacks were a catalytic moment that enabled a whole range of discursive positions to be articulated, defended, contested and given form in the media. They also made visible the potential tensions between free speech on the one hand, and hate and other problematic speech on the other. Using qualitative methods of thematic content analysis, document review, individual interviews, and an eclectic approach of framing analysis and rhetorical argumentation, this study found instances of divergence between the M&G policy and practice on User Generated Content. It found that some moderator-approved content advocated hate, hatred, hostility, incitement to violence and/or harm, and unfair discrimination against foreign residents, contrary to the M&G policy which is informed by the constitutional provisions in both section 16 of the Bill of Rights and section 10 of the Equality Act. Based on examples in the readers‟ comments of how „the foreigner‟ was made to signify unemployment, poverty, disease, unfair competition, and all manner of deprivation, and bearing in mind how such individuals have also become a site for the violent convergence of different unresolved tensions in the country, the study‟s findings argue that the M&G – a progressive paper dealing with a potentially xenophobic readership (at least a portion of it) – should have implemented its policy on acceptable speech more effectively. The study also argues that the unjustifiable reference to foreigners as makwerekwere, illegals, illegal aliens, parasites, invaders and border jumpers, among other terms, assigned them a diminished place – that of unwanted foreigner – thereby reproducing the order of discourse that utilises nationality as a space for the expurgation of the „other‟. The study argues that the use of bogus (inflated) immigration statistics and repeated reference to the foreigners‟ supposedly parasitic relationship to the country‟s resources also unfairly constructed them as the „threatening other‟ and potentially justified action against them.
- Full Text:
- Authors: Mwilu, Lwanga Racheal
- Date: 2010
- Subjects: Xenophobia in mass media -- South Africa Immigrants in mass media -- South Africa Mail & Guardian Thought leader Blogs -- South Africa Online hate speech -- South Africa Freedom of expression -- South Africa Online journalism -- Moral and ethical aspects
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3472 , http://hdl.handle.net/10962/d1002927
- Description: This study was conducted to identify and analyse Mail and Guardian Online moderation outputs which contradicted the platform‟s own stated policy on hate speech and other forms of problematic speech. The moderation outputs considered were a battery of readers‟ comments that were posted in response to Thought Leader blogs on xenophobia published between May and June, 2008. This was the same period a series of xenophobic attacks was taking place in some parts of South Africa, leaving an estimated 62 people dead, more than 30,000 displaced, and countless victims injured and robbed of their property. The attacks were a catalytic moment that enabled a whole range of discursive positions to be articulated, defended, contested and given form in the media. They also made visible the potential tensions between free speech on the one hand, and hate and other problematic speech on the other. Using qualitative methods of thematic content analysis, document review, individual interviews, and an eclectic approach of framing analysis and rhetorical argumentation, this study found instances of divergence between the M&G policy and practice on User Generated Content. It found that some moderator-approved content advocated hate, hatred, hostility, incitement to violence and/or harm, and unfair discrimination against foreign residents, contrary to the M&G policy which is informed by the constitutional provisions in both section 16 of the Bill of Rights and section 10 of the Equality Act. Based on examples in the readers‟ comments of how „the foreigner‟ was made to signify unemployment, poverty, disease, unfair competition, and all manner of deprivation, and bearing in mind how such individuals have also become a site for the violent convergence of different unresolved tensions in the country, the study‟s findings argue that the M&G – a progressive paper dealing with a potentially xenophobic readership (at least a portion of it) – should have implemented its policy on acceptable speech more effectively. The study also argues that the unjustifiable reference to foreigners as makwerekwere, illegals, illegal aliens, parasites, invaders and border jumpers, among other terms, assigned them a diminished place – that of unwanted foreigner – thereby reproducing the order of discourse that utilises nationality as a space for the expurgation of the „other‟. The study argues that the use of bogus (inflated) immigration statistics and repeated reference to the foreigners‟ supposedly parasitic relationship to the country‟s resources also unfairly constructed them as the „threatening other‟ and potentially justified action against them.
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Gaming culture: what lessons for pedagogy in South Africa?
- Kaschula, Russell H, Mostert, André M
- Authors: Kaschula, Russell H , Mostert, André M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175189 , vital:42551 , https://hdl.handle.net/10520/EJC30895
- Description: Gaming culture is becoming increasingly ubiquitous. Whereas before it was the reserve of those who were prepared to invest in the latest gaming hardware, increasingly powerful entry level machines coupled with more powerful mobile technologies are impacting on how young learners and students assimilate information. This evolving characteristic exhibited by the learners across South Africa must generate a serious reflection of education and training methodologies. Historically, education structures have been slow to embrace the changes that are imperative if the products of the process are to be adequately prepared for the future that faces them. One of the most telling realities of the modern era, or the planetary phase as it is now being tagged, is rapid change. The question that all educators need to ask is 'how is my pedagogic approach evolving'?.
- Full Text:
- Authors: Kaschula, Russell H , Mostert, André M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/175189 , vital:42551 , https://hdl.handle.net/10520/EJC30895
- Description: Gaming culture is becoming increasingly ubiquitous. Whereas before it was the reserve of those who were prepared to invest in the latest gaming hardware, increasingly powerful entry level machines coupled with more powerful mobile technologies are impacting on how young learners and students assimilate information. This evolving characteristic exhibited by the learners across South Africa must generate a serious reflection of education and training methodologies. Historically, education structures have been slow to embrace the changes that are imperative if the products of the process are to be adequately prepared for the future that faces them. One of the most telling realities of the modern era, or the planetary phase as it is now being tagged, is rapid change. The question that all educators need to ask is 'how is my pedagogic approach evolving'?.
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Gender and racial stereotyping in rape coverage: an analysis of rape coverage in Grocott's Mail
- Authors: Bonnes, Stephanie Marie
- Date: 2010
- Subjects: Grocott's Mail (Grahamstown, South Africa) Rape in mass media Rape -- South Africa Stereotypes (Social psychology) in mass media Sexism in mass media Racism in mass media Women -- Crimes against -- South Africa Violence in mass media Sex discrimination against women -- South Africa Journalism -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2762 , http://hdl.handle.net/10962/d1002972
- Description: This thesis analyzes rape coverage in a Grahamstown newspaper, Grocott’s Mail. Critical discourse analysis is used to discuss and analyze articles about rape that appear in Grocott’s Mail between October 14th 2008 and October 29th 2009. Drawing on existing literature on ‘rape myths’ in media coverage of rape, this thesis argues that Grocott’s Mail perpetuates racial and gender stereotypes through the way in which it reports on rape. While not all of the articles included in the analysis use rape myths, most use one or more when discussing rape incidents. Specifically, Grocott’s Mail tends to use rape myths that blame the victim for the rape and de-emphasize the role of the perpetrator in the rape. This is problematic as it sustains existing racial and gender inequalities.
- Full Text:
- Authors: Bonnes, Stephanie Marie
- Date: 2010
- Subjects: Grocott's Mail (Grahamstown, South Africa) Rape in mass media Rape -- South Africa Stereotypes (Social psychology) in mass media Sexism in mass media Racism in mass media Women -- Crimes against -- South Africa Violence in mass media Sex discrimination against women -- South Africa Journalism -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2762 , http://hdl.handle.net/10962/d1002972
- Description: This thesis analyzes rape coverage in a Grahamstown newspaper, Grocott’s Mail. Critical discourse analysis is used to discuss and analyze articles about rape that appear in Grocott’s Mail between October 14th 2008 and October 29th 2009. Drawing on existing literature on ‘rape myths’ in media coverage of rape, this thesis argues that Grocott’s Mail perpetuates racial and gender stereotypes through the way in which it reports on rape. While not all of the articles included in the analysis use rape myths, most use one or more when discussing rape incidents. Specifically, Grocott’s Mail tends to use rape myths that blame the victim for the rape and de-emphasize the role of the perpetrator in the rape. This is problematic as it sustains existing racial and gender inequalities.
- Full Text:
Generation of polyclonal antibodies against Theiler's Murine Encephalomyelitis virus protein 2C, and their use in investigating localisation of the protein in infected cells
- Authors: Jauka, Tembisa Innocencia
- Date: 2010
- Subjects: Picornaviruses , RNA viruses , Immunoglobulins , Encephalomyelitis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3959 , http://hdl.handle.net/10962/d1004018 , Picornaviruses , RNA viruses , Immunoglobulins , Encephalomyelitis
- Description: The Picornavirus family of positive sense RNA viruses includes some significant human and animal pathogens including Poliovirus (PV), Foot-and-Mouth disease virus (FMDV) and Human Rhinovirus (HRV). The genome is translated within the host cell into a polyprotein that is proteolytically cleaved into the structural and nonstructural proteins. The highly conserved, non-structural protein 2C has numerous roles during the virus life cycle and is essential for virus replication. Although the protein has been well studied in the case of PV, its interactions with the host cell during picornavirus infection is poorly understood. Theiler’s Encephalomyelitis virus (TMEV) is a picornavirus that infects mice, and is being used in our laboratory as a model in which to study the 2C protein. In this study, polyclonal antibodies against the TMEV 2C protein were generated and used to localise the protein in infected cells by indirect immunofluorescence. To produce antigen for immunisation purposes, the TMEV-2C protein sequence was analysed to identify hydrophilic and antigenic regions. An internal region of the 2C representing amino acid residues 31-210 was selected, expressed in bacteria and purified by nickel NTA affinity chromatography. Time course analysis of 2C (31-210) showed that the peptide was maximally expressed at 5 hours post induction. The peptide was solubilised using a mild detergent and 1.5 mg of purified antigen was used for immunisation of rabbits. Western blot analysis confirmed that the antibodies could detect both bacteriallyexpressed antigen, and virally-expressed 2C. Examination of virus-infected baby hamster kidney cells by immunofluorescence and confocal microscopy using the antiserum (anti-TMEV 2C antibodies) showed that the protein had a diffuse distribution upon early infection and at later stages it was located in a large perinuclear structure representing the viral replication complex. Furthermore, 2C localised to the Golgi apparatus as revealed by dual-label immunofluorescence using anti-TMEV 2C antibodies and wheat germ agglutinin (WGA). Furthermore, it was shown that TMEV infection results in changes in cell morphology and a redistribution of the cytoskeletal protein, β-actin. The successful production of antibodies that recognise TMEV 2C opens the way for further studies to investigate interactions between 2C and hostencoded factors.
- Full Text:
- Authors: Jauka, Tembisa Innocencia
- Date: 2010
- Subjects: Picornaviruses , RNA viruses , Immunoglobulins , Encephalomyelitis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3959 , http://hdl.handle.net/10962/d1004018 , Picornaviruses , RNA viruses , Immunoglobulins , Encephalomyelitis
- Description: The Picornavirus family of positive sense RNA viruses includes some significant human and animal pathogens including Poliovirus (PV), Foot-and-Mouth disease virus (FMDV) and Human Rhinovirus (HRV). The genome is translated within the host cell into a polyprotein that is proteolytically cleaved into the structural and nonstructural proteins. The highly conserved, non-structural protein 2C has numerous roles during the virus life cycle and is essential for virus replication. Although the protein has been well studied in the case of PV, its interactions with the host cell during picornavirus infection is poorly understood. Theiler’s Encephalomyelitis virus (TMEV) is a picornavirus that infects mice, and is being used in our laboratory as a model in which to study the 2C protein. In this study, polyclonal antibodies against the TMEV 2C protein were generated and used to localise the protein in infected cells by indirect immunofluorescence. To produce antigen for immunisation purposes, the TMEV-2C protein sequence was analysed to identify hydrophilic and antigenic regions. An internal region of the 2C representing amino acid residues 31-210 was selected, expressed in bacteria and purified by nickel NTA affinity chromatography. Time course analysis of 2C (31-210) showed that the peptide was maximally expressed at 5 hours post induction. The peptide was solubilised using a mild detergent and 1.5 mg of purified antigen was used for immunisation of rabbits. Western blot analysis confirmed that the antibodies could detect both bacteriallyexpressed antigen, and virally-expressed 2C. Examination of virus-infected baby hamster kidney cells by immunofluorescence and confocal microscopy using the antiserum (anti-TMEV 2C antibodies) showed that the protein had a diffuse distribution upon early infection and at later stages it was located in a large perinuclear structure representing the viral replication complex. Furthermore, 2C localised to the Golgi apparatus as revealed by dual-label immunofluorescence using anti-TMEV 2C antibodies and wheat germ agglutinin (WGA). Furthermore, it was shown that TMEV infection results in changes in cell morphology and a redistribution of the cytoskeletal protein, β-actin. The successful production of antibodies that recognise TMEV 2C opens the way for further studies to investigate interactions between 2C and hostencoded factors.
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Geology of the Kroonstad kimberlite cluster, South Africa
- Authors: Howarth, Geoffrey H
- Date: 2010
- Subjects: Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4961 , http://hdl.handle.net/10962/d1005573 , Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Description: The Cretaceous (133Ma) Kroonstad Group II Kimberlite Cluster is located approximately 200km south west of Johannesburg on the Kaapvaal Craton. The cluster is made up of six kimberlite pipes and numerous other intrusive dike/sill bodies. Three of the pipes are analysed in this study, which includes the: Voorspoed, Lace (Crown) and Besterskraal North pipes. These pipes were emplaced at surface into the Karoo Supergroup, which is comprised of older sedimentary rocks (300-185Ma) overlain by flood basalts (185Ma). At depth the pipes have intruded the Transvaal (2100-2600Ma) and Ventersdorp (2700Ma) Supergroups, which are comprised dominantly of carbonates and various volcanic units respectively. The pipes have typical morphology of South African pipes with circular to sub-circular plan views and steep 82o pipe margins. The Voorspoed pipe is 12ha in size and is characterised by the presence of a large block of Karoo basalt approximately 6ha in size at the current land surface. This large basalt block extends to a maximum of 300m below the current land surface. The main Lace pipe is 2ha is size with a smaller (<0.5ha) satellite pipe approximately 50m to the west. No information is available on the morphology of the Besterskraal North pipe as it is sub-economic and no mining has occurred. Samples from the Besterskraal North pipe were collected from the De Beers archives. The Kroonstad Cluster has been subjected to approximately 1750m of erosion post-emplacement, which has been calculated by the analysis of the crustal xenoliths with the pipe infill. The hypabyssal kimberlite from the three pipes shows a gradational evolution in magma compositions, indicated by the mineralogy and geochemistry. The Lace pipe is the least evolved and has characteristics more similar to Group I kimberlites. The Voorspoed and Besterskraal North kimberlite are intermediately and highly evolved respectively. The gradational evolution is marked by an increase in SiO2 and Na2O contents. Furthermore the occurrence of abundant primary diopside, aegirine, sanidine, K-richterite and leucite indicates evolution of the magma. The root zones of the pipes are characterised by globular segregationary transitional kimberlite, which is interpreted to be hypabyssal and not the result of pyroclastic welding/agglutination. The hypabyssal transitional kimberlite (HKt) is characterised by incipient globular segregationary textures only and the typical tuffisitic transitional kimberlite (TKt) end member (Hetman et al. 2004) is not observed. The HKt contact with the overlying volcaniclastic kimberlite (VK) infill is sharp and not gradational. The presence of HKt in the satellite blind pipe at Lace further indicates that the distinct kimberlite rock type must be forming sub-volcanically. The HKt is distinctly different at the Voorspoed and Lace pipes, which is likely a result of differing compositions of the late stage magmatic liquid. Microlitic clinopyroxene is only observed at the Lace HKt and is interpreted to form as a result of both crustal xenolith contamination and CO2 degassing. Furthermore the HKt is intimately associated with contact breccias in the sidewall. The root zones of the Kroonstad pipes are interpreted to form through the development of a sub-volcanic embryonic pipe. The volcaniclastic kimberlite (VK) infill of the Kroonstad pipes is not typical of South African tuffisitic Class 1 kimberlite pipes. The VK at Voorspoed is characterised by numerous horizontally layered massive volcaniclastic kimberlite (MVK) units, which are interpreted to have formed in a deep open vent through primary pyroclastic deposition. MVK is the dominant rock type infilling the Voorspoed pipe, however numerous other minor units occur. Normally graded units are interpreted to form through gravitational collapse of the tuff ring. MVK units rich in Karoo basalt and/or Karoo sandstone are interpreted to form through gravitational sidewall failure deep within an open vent. Magmaclasts are interpreted to form in the HKt during the development of an embryonic pipe and therefore the term autolith or nucleated autolith may be applied. Debate on the validity of the term nucleated autolith is beyond this study and therefore the term nucleated magmaclast is used to refer to spherical magmaclasts in the VK. The emplacement of the Kroonstad pipes is particularly complex and is not similar to typical Class 1 tuffisitic kimberlites. However the initial stage of pipe emplacement is similar to typical South African kimberlites and is interpreted to be through the development of an embryonic pipe as described by Clement (1982). The vent clearing eruption is interpreted to be from the bottom up through the exsolution of juvenile volatiles and the pipe shape is controlled by the depth of the eruption (+/-2km) (Skinner, 2008). The initial embryonic pipe development and explosive eruption is similar to other South African kimberlites, however the vent is cleared and left open, which is typical of Class 2 Prairies type and Class 3 Lac de Gras type pipes. The latter vent infilling processes are similar to Class 3 kimberlites from Lac de Gras and are dominated at the current level by primary pyroclastic deposition.
- Full Text:
- Authors: Howarth, Geoffrey H
- Date: 2010
- Subjects: Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4961 , http://hdl.handle.net/10962/d1005573 , Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Description: The Cretaceous (133Ma) Kroonstad Group II Kimberlite Cluster is located approximately 200km south west of Johannesburg on the Kaapvaal Craton. The cluster is made up of six kimberlite pipes and numerous other intrusive dike/sill bodies. Three of the pipes are analysed in this study, which includes the: Voorspoed, Lace (Crown) and Besterskraal North pipes. These pipes were emplaced at surface into the Karoo Supergroup, which is comprised of older sedimentary rocks (300-185Ma) overlain by flood basalts (185Ma). At depth the pipes have intruded the Transvaal (2100-2600Ma) and Ventersdorp (2700Ma) Supergroups, which are comprised dominantly of carbonates and various volcanic units respectively. The pipes have typical morphology of South African pipes with circular to sub-circular plan views and steep 82o pipe margins. The Voorspoed pipe is 12ha in size and is characterised by the presence of a large block of Karoo basalt approximately 6ha in size at the current land surface. This large basalt block extends to a maximum of 300m below the current land surface. The main Lace pipe is 2ha is size with a smaller (<0.5ha) satellite pipe approximately 50m to the west. No information is available on the morphology of the Besterskraal North pipe as it is sub-economic and no mining has occurred. Samples from the Besterskraal North pipe were collected from the De Beers archives. The Kroonstad Cluster has been subjected to approximately 1750m of erosion post-emplacement, which has been calculated by the analysis of the crustal xenoliths with the pipe infill. The hypabyssal kimberlite from the three pipes shows a gradational evolution in magma compositions, indicated by the mineralogy and geochemistry. The Lace pipe is the least evolved and has characteristics more similar to Group I kimberlites. The Voorspoed and Besterskraal North kimberlite are intermediately and highly evolved respectively. The gradational evolution is marked by an increase in SiO2 and Na2O contents. Furthermore the occurrence of abundant primary diopside, aegirine, sanidine, K-richterite and leucite indicates evolution of the magma. The root zones of the pipes are characterised by globular segregationary transitional kimberlite, which is interpreted to be hypabyssal and not the result of pyroclastic welding/agglutination. The hypabyssal transitional kimberlite (HKt) is characterised by incipient globular segregationary textures only and the typical tuffisitic transitional kimberlite (TKt) end member (Hetman et al. 2004) is not observed. The HKt contact with the overlying volcaniclastic kimberlite (VK) infill is sharp and not gradational. The presence of HKt in the satellite blind pipe at Lace further indicates that the distinct kimberlite rock type must be forming sub-volcanically. The HKt is distinctly different at the Voorspoed and Lace pipes, which is likely a result of differing compositions of the late stage magmatic liquid. Microlitic clinopyroxene is only observed at the Lace HKt and is interpreted to form as a result of both crustal xenolith contamination and CO2 degassing. Furthermore the HKt is intimately associated with contact breccias in the sidewall. The root zones of the Kroonstad pipes are interpreted to form through the development of a sub-volcanic embryonic pipe. The volcaniclastic kimberlite (VK) infill of the Kroonstad pipes is not typical of South African tuffisitic Class 1 kimberlite pipes. The VK at Voorspoed is characterised by numerous horizontally layered massive volcaniclastic kimberlite (MVK) units, which are interpreted to have formed in a deep open vent through primary pyroclastic deposition. MVK is the dominant rock type infilling the Voorspoed pipe, however numerous other minor units occur. Normally graded units are interpreted to form through gravitational collapse of the tuff ring. MVK units rich in Karoo basalt and/or Karoo sandstone are interpreted to form through gravitational sidewall failure deep within an open vent. Magmaclasts are interpreted to form in the HKt during the development of an embryonic pipe and therefore the term autolith or nucleated autolith may be applied. Debate on the validity of the term nucleated autolith is beyond this study and therefore the term nucleated magmaclast is used to refer to spherical magmaclasts in the VK. The emplacement of the Kroonstad pipes is particularly complex and is not similar to typical Class 1 tuffisitic kimberlites. However the initial stage of pipe emplacement is similar to typical South African kimberlites and is interpreted to be through the development of an embryonic pipe as described by Clement (1982). The vent clearing eruption is interpreted to be from the bottom up through the exsolution of juvenile volatiles and the pipe shape is controlled by the depth of the eruption (+/-2km) (Skinner, 2008). The initial embryonic pipe development and explosive eruption is similar to other South African kimberlites, however the vent is cleared and left open, which is typical of Class 2 Prairies type and Class 3 Lac de Gras type pipes. The latter vent infilling processes are similar to Class 3 kimberlites from Lac de Gras and are dominated at the current level by primary pyroclastic deposition.
- Full Text:
Global Climate Change, Adaptation and Abatement in a Context of Risk and Vulnerability
- Lotz-Sisitka, Heila, Le Grange, Lesley
- Authors: Lotz-Sisitka, Heila , Le Grange, Lesley
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/437338 , vital:73371 , ISBN 9780826440655 , https://www.bloomsbury.com/us/climate-change-and-philosophy-9780826440655/
- Description: Climate Change and Philosophy presents ten original es-says by an international team of expert contributors, ex-ploring the important contribution philosophical inquiry can make to contemporary debates to do with climate change and the global environment. Examining this hugely topical issue through the lens of environmental philosophy, political theory, philosophy of technology, philosophy of education and feminist theory, these es-says interrogate some of the presumptions that inform modernity and our interaction with natural processes. The book asks fundamental questions about human na-ture and, more importantly, the concept of 'nature' itself. The conceptual frameworks presented here contribute to an understanding of the processes of change, of social transformation, and the means of adapting to the con-straints that problems such as climate change pose. The book proposes a way of beginning the important task of rethinking the relationship between humanity and the natural environment. Through enquiry into the basic philosophical principles that inform modern society, each author asserts that reflection informs change and that change is both required and possible in the context of the environmental crisis facing us today.
- Full Text:
- Authors: Lotz-Sisitka, Heila , Le Grange, Lesley
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/437338 , vital:73371 , ISBN 9780826440655 , https://www.bloomsbury.com/us/climate-change-and-philosophy-9780826440655/
- Description: Climate Change and Philosophy presents ten original es-says by an international team of expert contributors, ex-ploring the important contribution philosophical inquiry can make to contemporary debates to do with climate change and the global environment. Examining this hugely topical issue through the lens of environmental philosophy, political theory, philosophy of technology, philosophy of education and feminist theory, these es-says interrogate some of the presumptions that inform modernity and our interaction with natural processes. The book asks fundamental questions about human na-ture and, more importantly, the concept of 'nature' itself. The conceptual frameworks presented here contribute to an understanding of the processes of change, of social transformation, and the means of adapting to the con-straints that problems such as climate change pose. The book proposes a way of beginning the important task of rethinking the relationship between humanity and the natural environment. Through enquiry into the basic philosophical principles that inform modern society, each author asserts that reflection informs change and that change is both required and possible in the context of the environmental crisis facing us today.
- Full Text:
Global resonance, local amplification: Antjie Krog on a world stage
- Authors: Garman, Anthea
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159736 , vital:40338 , https://doi.org/10.1080/02533950903562468
- Description: As a result of the publication of Country of my Skull, an extraordinary literary enactment of witness and confession, Antjie Krog has become internationally known as a writer profoundly engaged with the events and human drama uncovered by the South African Truth and Reconciliation Commission. Her voice is read as that of an expert witness of trauma, forgiveness and the means by which the horrors of the past may be addressed. In seeking to understand how Krog came to be taken up internationally as a representative voice of the South African transition, I focus on a particular global–local nexus for an explanation. I theorise that dealing with the past via truth commissions, a global publishing context and the work of a local writer with a record of excellent literary output and political action enabled a fit which resulted in Krog coming to prominence on a world stage.
- Full Text:
- Authors: Garman, Anthea
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159736 , vital:40338 , https://doi.org/10.1080/02533950903562468
- Description: As a result of the publication of Country of my Skull, an extraordinary literary enactment of witness and confession, Antjie Krog has become internationally known as a writer profoundly engaged with the events and human drama uncovered by the South African Truth and Reconciliation Commission. Her voice is read as that of an expert witness of trauma, forgiveness and the means by which the horrors of the past may be addressed. In seeking to understand how Krog came to be taken up internationally as a representative voice of the South African transition, I focus on a particular global–local nexus for an explanation. I theorise that dealing with the past via truth commissions, a global publishing context and the work of a local writer with a record of excellent literary output and political action enabled a fit which resulted in Krog coming to prominence on a world stage.
- Full Text:
Goat production in the Northern Cape: what are the impacts of farmer training?
- Authors: Burgess, Roberta
- Date: 2010
- Subjects: Northern Cape (South Africa) Animal culture -- South Africa -- Northern Cape -- Management Animal culture -- Economic aspects -- South Africa -- Northern Cape Goat farmers -- South Africa -- Northern Cape -- Education
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:747 , http://hdl.handle.net/10962/d1003868
- Description: The main millennium development goal is to eradicate extreme poverty and hunger in the world by 2015. South Africa is one of the countries that signed this pledge at the millennium summit in 2000. The Department of Agriculture, has initiated a number of projects to assist farmers and communities with reaching this goal. In the Northern Cape, the commercialization of goats is one such anchor project. The major activities of this project is to train farmers in applied and appropriate production practices, assist them with accessing markets and supporting them with improved livestock. The main aim of this research was to evaluate whether the project has achieved its outcome and whether this outcome, is having an impact on the livelihoods of the farmers involved in the project. After reviewing the literature on evaluation research and programme evaluation across time, the different paradigms and approaches, participatory methodology was used in this study. A case study approach was applied to evaluate the outcomes and effects of the training received by farmers, as part of the commercialization of goats programme. The results of the study proved that the training received by members of the Campbell Agricultural Co-operative Enterprises, changed their goat production practices. The training also had a secondary impact. Trained farmers were imparting (technology transfer) their acquired knowledge to other members of the co-operative. This appeared very effective as all members of the cooperative were farming more scientifically. These changes to the production practices had a positive impact on the livelihoods of the farmers, as their animals were of a better quality and they were able to sell their animals at different markets and for better prices. This has however not commercialized their farming operations as they are still faced with many challenges. These challenges are the lack of a proper marketing structure, access to financial assistance, proper infrastructure and adequate transport for the animals to mention a few. If the Department of Agriculture and Land Affairs is serious about assisting these farmers to move from the status of “emerging farmer” to “commercial farmer” they will have to look at addressing the problems experienced with financial access and access to adequate and appropriate transport.
- Full Text:
- Authors: Burgess, Roberta
- Date: 2010
- Subjects: Northern Cape (South Africa) Animal culture -- South Africa -- Northern Cape -- Management Animal culture -- Economic aspects -- South Africa -- Northern Cape Goat farmers -- South Africa -- Northern Cape -- Education
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:747 , http://hdl.handle.net/10962/d1003868
- Description: The main millennium development goal is to eradicate extreme poverty and hunger in the world by 2015. South Africa is one of the countries that signed this pledge at the millennium summit in 2000. The Department of Agriculture, has initiated a number of projects to assist farmers and communities with reaching this goal. In the Northern Cape, the commercialization of goats is one such anchor project. The major activities of this project is to train farmers in applied and appropriate production practices, assist them with accessing markets and supporting them with improved livestock. The main aim of this research was to evaluate whether the project has achieved its outcome and whether this outcome, is having an impact on the livelihoods of the farmers involved in the project. After reviewing the literature on evaluation research and programme evaluation across time, the different paradigms and approaches, participatory methodology was used in this study. A case study approach was applied to evaluate the outcomes and effects of the training received by farmers, as part of the commercialization of goats programme. The results of the study proved that the training received by members of the Campbell Agricultural Co-operative Enterprises, changed their goat production practices. The training also had a secondary impact. Trained farmers were imparting (technology transfer) their acquired knowledge to other members of the co-operative. This appeared very effective as all members of the cooperative were farming more scientifically. These changes to the production practices had a positive impact on the livelihoods of the farmers, as their animals were of a better quality and they were able to sell their animals at different markets and for better prices. This has however not commercialized their farming operations as they are still faced with many challenges. These challenges are the lack of a proper marketing structure, access to financial assistance, proper infrastructure and adequate transport for the animals to mention a few. If the Department of Agriculture and Land Affairs is serious about assisting these farmers to move from the status of “emerging farmer” to “commercial farmer” they will have to look at addressing the problems experienced with financial access and access to adequate and appropriate transport.
- Full Text:
Google docs and skype for a low bandwidth virtual classroom for developing countries
- Thinyane, Hannah, Mufeti, Tulimevava K, Terzoli, Alfredo, Wright, Madeleine
- Authors: Thinyane, Hannah , Mufeti, Tulimevava K , Terzoli, Alfredo , Wright, Madeleine
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430757 , vital:72713 , https://ieeexplore.ieee.org/abstract/document/5753006
- Description: There has been much attention recently on the use of virtual class-rooms to support distance learning. However, the required real-time and high-rate transfers for multimedia contents such as video and audio that comprise most off-the-shelf virtual classrooms make them infeasible for developing countries where bandwidth is typically more restricted. This paper describes the findings of an ongoing investigation to develop a low bandwidth virtual classroom that can provide the necessary func-tionality to deliver courses to distant students. By combining Google Docs and Skype, we realised a low bandwidth virtual classroom alterna-tive that could provide adequate functionality within our teaching con-text.
- Full Text:
- Authors: Thinyane, Hannah , Mufeti, Tulimevava K , Terzoli, Alfredo , Wright, Madeleine
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430757 , vital:72713 , https://ieeexplore.ieee.org/abstract/document/5753006
- Description: There has been much attention recently on the use of virtual class-rooms to support distance learning. However, the required real-time and high-rate transfers for multimedia contents such as video and audio that comprise most off-the-shelf virtual classrooms make them infeasible for developing countries where bandwidth is typically more restricted. This paper describes the findings of an ongoing investigation to develop a low bandwidth virtual classroom that can provide the necessary func-tionality to deliver courses to distant students. By combining Google Docs and Skype, we realised a low bandwidth virtual classroom alterna-tive that could provide adequate functionality within our teaching con-text.
- Full Text:
Government failure and state incapacity: the South African public sector in the 1990s
- Dollery, Brian, Snowball, Jeanette D
- Authors: Dollery, Brian , Snowball, Jeanette D
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71343 , vital:29835 , https://doi.org/10.1080/10113430309511164
- Description: In their editorial introduction to the 1994 Special Issue of the South African Journal of Economic History devoted to a sectoral analysis of the South African economy during the 1980s, Stuart Jones and Jon Inggs described this period as a "lost decade", with per capita incomes even lower in 1990 than they had been in 1980. Moreover, "no other Western country experienced a comparable decline in the 1980s and South Africa herself had never experienced anything like it since the formation of Union in 1910". Thus, from the perspective of economic growth, the decade of the 1990s could not have had a less auspicious beginning.
- Full Text: false
- Authors: Dollery, Brian , Snowball, Jeanette D
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71343 , vital:29835 , https://doi.org/10.1080/10113430309511164
- Description: In their editorial introduction to the 1994 Special Issue of the South African Journal of Economic History devoted to a sectoral analysis of the South African economy during the 1980s, Stuart Jones and Jon Inggs described this period as a "lost decade", with per capita incomes even lower in 1990 than they had been in 1980. Moreover, "no other Western country experienced a comparable decline in the 1980s and South Africa herself had never experienced anything like it since the formation of Union in 1910". Thus, from the perspective of economic growth, the decade of the 1990s could not have had a less auspicious beginning.
- Full Text: false
Growth and longevity of Exosphaeroma hylocoetes (Isopoda) under varying conditions of salinity and temperature
- Henninger, Tony O, Froneman, P William, Booth, Anthony J, Hodgson, Alan N
- Authors: Henninger, Tony O , Froneman, P William , Booth, Anthony J , Hodgson, Alan N
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124571 , vital:35630 , https://doi.org/10.3377/004.045.0118
- Description: Numerous studies have documented the importance of both temperature and salinity in influencing aquatic crustacean metabolic processes such as respiration and growth. For example, increased water temperatures have been shown to increase respiration rates in various species of shrimp (Chen & Nan 1993; Spanonopoulos-Hernándeza et al. 2005; Allan et al. 2006), and copepods (Isla & Perissinotto 2004). The response of invertebrates to changes in salinity is more complex, largely reflecting their evolutionary origins (Kinne 1966). For example, juvenile blue swimming crabs, Portunus pelagicus, displayed significantly faster growth and higher survival in response to increasingsalinity (Romano & Zeng 2006). Additional factors that may influence the growth rates of crustaceans include photoperiod (Gambardella et al. 1997), food availability (Shuster & Guthrie 1999) and sex (Newman et al. 2007).
- Full Text:
- Authors: Henninger, Tony O , Froneman, P William , Booth, Anthony J , Hodgson, Alan N
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124571 , vital:35630 , https://doi.org/10.3377/004.045.0118
- Description: Numerous studies have documented the importance of both temperature and salinity in influencing aquatic crustacean metabolic processes such as respiration and growth. For example, increased water temperatures have been shown to increase respiration rates in various species of shrimp (Chen & Nan 1993; Spanonopoulos-Hernándeza et al. 2005; Allan et al. 2006), and copepods (Isla & Perissinotto 2004). The response of invertebrates to changes in salinity is more complex, largely reflecting their evolutionary origins (Kinne 1966). For example, juvenile blue swimming crabs, Portunus pelagicus, displayed significantly faster growth and higher survival in response to increasingsalinity (Romano & Zeng 2006). Additional factors that may influence the growth rates of crustaceans include photoperiod (Gambardella et al. 1997), food availability (Shuster & Guthrie 1999) and sex (Newman et al. 2007).
- Full Text:
Growth, reproduction and population structure of Diplotaxodon limnothrissa in the southeast arm of Lake Malawi
- Kanyerere, Geoffrey Z, Weyl, Olaf L F, Booth, Anthony J
- Authors: Kanyerere, Geoffrey Z , Weyl, Olaf L F , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124583 , vital:35633 , https://doi.org/10.2989/16085910509503832
- Description: With a surface area of ca 28 800km2, Lake Malawi (9°30’S–14°30’S) is the second largest of the African Rift Valley lakes, supporting at least 500, and possibly 2 000, fish species (Turner 1995). The ichthyofauna is dominated by haplochomine cichlids, most of which are confined to the demersal and littoral zones. As a result of over-fishing, the abundance of many of these species has declined (Turner 1994a, 1995, Bulirani et al. 1999, Allison et al. 2002). In contrast, the lake’s offshore fish stocks are considered to be unexploited or only lightly exploited (Thompson and Allison 1997, Turner et al. 2000) and the redirection of fishing effort to these stocks is a high priority (Thompson and Allison 1997, Turner et al. 2000, Allison et al. 2002). Consequently, the Malawi government is currently collaborating with the African Development Bank to develop the deepwater/ offshore fishery in order to increase yields by an estimated 11 000 tons (MC Banda, National Research co-ordinator, pers. comm.). The most abundant cichlid species in the pelagic zone is the small (<210mm TL) zooplanktivorous Diplotaxodon limnothrissa (Turner 1994, Thompson and Allison 1997). It has been recorded throughout the lake at depths ranging from 20 metres down to the anoxic zone at ca 220 metres (Turner 1994b, Thompson et al. 1996, Duponchelle et al. 2000a) and it makes up ca 52% to the total fish biomass (Thompson and Allison 1997). Diplotaxodon limnothrissa will therefore be a major target species in the pelagic fishery, and already comprises in excess of 50% of the mid-water trawl fishery in the southeast arm (SEA) of the lake (Turner 1996).
- Full Text:
- Authors: Kanyerere, Geoffrey Z , Weyl, Olaf L F , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124583 , vital:35633 , https://doi.org/10.2989/16085910509503832
- Description: With a surface area of ca 28 800km2, Lake Malawi (9°30’S–14°30’S) is the second largest of the African Rift Valley lakes, supporting at least 500, and possibly 2 000, fish species (Turner 1995). The ichthyofauna is dominated by haplochomine cichlids, most of which are confined to the demersal and littoral zones. As a result of over-fishing, the abundance of many of these species has declined (Turner 1994a, 1995, Bulirani et al. 1999, Allison et al. 2002). In contrast, the lake’s offshore fish stocks are considered to be unexploited or only lightly exploited (Thompson and Allison 1997, Turner et al. 2000) and the redirection of fishing effort to these stocks is a high priority (Thompson and Allison 1997, Turner et al. 2000, Allison et al. 2002). Consequently, the Malawi government is currently collaborating with the African Development Bank to develop the deepwater/ offshore fishery in order to increase yields by an estimated 11 000 tons (MC Banda, National Research co-ordinator, pers. comm.). The most abundant cichlid species in the pelagic zone is the small (<210mm TL) zooplanktivorous Diplotaxodon limnothrissa (Turner 1994, Thompson and Allison 1997). It has been recorded throughout the lake at depths ranging from 20 metres down to the anoxic zone at ca 220 metres (Turner 1994b, Thompson et al. 1996, Duponchelle et al. 2000a) and it makes up ca 52% to the total fish biomass (Thompson and Allison 1997). Diplotaxodon limnothrissa will therefore be a major target species in the pelagic fishery, and already comprises in excess of 50% of the mid-water trawl fishery in the southeast arm (SEA) of the lake (Turner 1996).
- Full Text:
Handspring Puppet Company, Jane Taylor (Ed.)
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229658 , vital:49697 , xlink:href="https://0hdl.handle.net.wam.seals.ac.za/10520/EJC31088"
- Description: Handspring Puppet Company recently won three prestigious London awards (including the Olivier) for their design of the production War Horse, which is still running to great acclaim in the West End. This beautiful book has been released at exactly the right time, at a highpoint of an extraordinary company which has been producing astonishing work for 28 years already. It is an appropriate celebration of their many marvellous designs for 11 plays and two operas.
- Full Text:
- Authors: Krueger, Anton
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229658 , vital:49697 , xlink:href="https://0hdl.handle.net.wam.seals.ac.za/10520/EJC31088"
- Description: Handspring Puppet Company recently won three prestigious London awards (including the Olivier) for their design of the production War Horse, which is still running to great acclaim in the West End. This beautiful book has been released at exactly the right time, at a highpoint of an extraordinary company which has been producing astonishing work for 28 years already. It is an appropriate celebration of their many marvellous designs for 11 plays and two operas.
- Full Text:
Hipper redacted:
- Authors: Jamal, Ashraf
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147902 , vital:38683 , DOI: 10.1080/02560046.2010.511888
- Description: The work of contemporary South African artist, mark Hipper, has been dogged by controversy.
- Full Text:
- Authors: Jamal, Ashraf
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147902 , vital:38683 , DOI: 10.1080/02560046.2010.511888
- Description: The work of contemporary South African artist, mark Hipper, has been dogged by controversy.
- Full Text:
Hippocampus: seahorse; brain-structure; spatial map; concept
- Authors: Armstrong, Beth Diane
- Date: 2010
- Subjects: Hippocampus (Brain) Sea horses -- Symbolic representation Meaning (Philosophy) Deleuze, Gilles, 1925-1995 Escher, M C (Maurits Cornelis), 1898-1972 Visual perception Space perception Optical art Art -- Themes, motives
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2427 , http://hdl.handle.net/10962/d1002224
- Description: Through an exploration of both sculptural and thought processes undertaken in making my Masters exhibition, ‘Hippocampus’, I unpack some possibilities, instabilities, and limitations inherent in representation and visual perception. This thesis explores the Hippocampus as image (seahorse) and concept (brain-structure involved in cognitive mapping of space). Looking at Gilles Deleuze’s writings on representation, I will expand on the notion of the map as being that which does not define and fix a structure or meaning, but rather is open, extendable and experimental. I explore the becoming, rather than the being, of image and concept. The emphasis here is on process, non-representation, and fluidity of meaning. This is supportive of my personal affirmation of the practice and process of art-making as research. I will refer to the graphic prints of Maurits Cornelis Escher as a means to elucidate a visual contextualization of my practical work, particularly with regard to the play with two- and three-dimensional space perception. Through precisely calculated ‘experiments’ that show up the partiality of our visual perception of space, Escher alludes to things that either cannot actually exist as spatial objects or do exist, but resist representation. Similarly I will explore how my own sculptures, although existing in space resist a fixed representation and suggest ideas of other spaces, non-spaces; an in-between space that does not pin itself down and become fixed to any particular image, idea, objector representation.
- Full Text:
- Authors: Armstrong, Beth Diane
- Date: 2010
- Subjects: Hippocampus (Brain) Sea horses -- Symbolic representation Meaning (Philosophy) Deleuze, Gilles, 1925-1995 Escher, M C (Maurits Cornelis), 1898-1972 Visual perception Space perception Optical art Art -- Themes, motives
- Language: English
- Type: Thesis , Masters , MFA
- Identifier: vital:2427 , http://hdl.handle.net/10962/d1002224
- Description: Through an exploration of both sculptural and thought processes undertaken in making my Masters exhibition, ‘Hippocampus’, I unpack some possibilities, instabilities, and limitations inherent in representation and visual perception. This thesis explores the Hippocampus as image (seahorse) and concept (brain-structure involved in cognitive mapping of space). Looking at Gilles Deleuze’s writings on representation, I will expand on the notion of the map as being that which does not define and fix a structure or meaning, but rather is open, extendable and experimental. I explore the becoming, rather than the being, of image and concept. The emphasis here is on process, non-representation, and fluidity of meaning. This is supportive of my personal affirmation of the practice and process of art-making as research. I will refer to the graphic prints of Maurits Cornelis Escher as a means to elucidate a visual contextualization of my practical work, particularly with regard to the play with two- and three-dimensional space perception. Through precisely calculated ‘experiments’ that show up the partiality of our visual perception of space, Escher alludes to things that either cannot actually exist as spatial objects or do exist, but resist representation. Similarly I will explore how my own sculptures, although existing in space resist a fixed representation and suggest ideas of other spaces, non-spaces; an in-between space that does not pin itself down and become fixed to any particular image, idea, objector representation.
- Full Text:
Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae)
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124593 , vital:35634 , https://doi.org/10.1080/15627020.2000.11657094
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
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Historical biogeography of the tribe Platypleurini Schmidt, 1918 (Hemiptera: Cicadidae) with a focus on Southern Africa
- Authors: Price, Benjamin Wills
- Date: 2010
- Subjects: Biogeography -- History -- Africa, Southern Cicadas -- Africa, Southern Cicada (Genus) -- Africa, Southern Biodiversity -- Africa, Southern Cicadas -- Variation -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5708 , http://hdl.handle.net/10962/d1005394
- Description: With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.
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- Authors: Price, Benjamin Wills
- Date: 2010
- Subjects: Biogeography -- History -- Africa, Southern Cicadas -- Africa, Southern Cicada (Genus) -- Africa, Southern Biodiversity -- Africa, Southern Cicadas -- Variation -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5708 , http://hdl.handle.net/10962/d1005394
- Description: With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.
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How the leopard has changed its spots: past dynamics and future opportunities
- Authors: Fraser, Gavin C G
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/472988 , vital:77596 , https://hdl.handle.net/10520/EJC18437
- Description: I feel very humbled being afforded the opportunity to present the FR Tomlinson Commemorative Lecture. In the process of preparing this lecture, I looked up the previous presenters of the lecture and saw the names of eminent agricultural economists who have made major contributions to the subject in South Africa. I feel extremely proud to be included in such a prominent group and it made me to feel somewhat of an interloper amongst the likes of, inter alia, FR Tomlinson, Eckart Kassier, Lieb Nieuwoudt and Johan van Zyl.
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- Authors: Fraser, Gavin C G
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/472988 , vital:77596 , https://hdl.handle.net/10520/EJC18437
- Description: I feel very humbled being afforded the opportunity to present the FR Tomlinson Commemorative Lecture. In the process of preparing this lecture, I looked up the previous presenters of the lecture and saw the names of eminent agricultural economists who have made major contributions to the subject in South Africa. I feel extremely proud to be included in such a prominent group and it made me to feel somewhat of an interloper amongst the likes of, inter alia, FR Tomlinson, Eckart Kassier, Lieb Nieuwoudt and Johan van Zyl.
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