Cryptic variation in an ecological indicator organism: mitochondrial and nuclear DNA sequence data confirm distinct lineages of Baetis harrisoni Barnard (Ephemeroptera: Baetidae) in southern Africa
- Pereira-da-Conceicoa, L L, Price, Benjamin W, Barber-James, Helen M
- Authors: Pereira-da-Conceicoa, L L , Price, Benjamin W , Barber-James, Helen M
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7151 , http://hdl.handle.net/10962/d1011855
- Description: Baetis harrisoni Barnard is a mayfly frequently encountered in river studies across Africa, but the external morphological features used for identifying nymphs have been observed to vary subtly between different geographic locations. It has been associated with a wide range of ecological conditions, including pH extremes of pH 2.9–10.0 in polluted waters. We present a molecular study of the genetic variation within B. harrisoni across 21 rivers in its distribution range in southern Africa.
- Full Text:
- Date Issued: 2012
- Authors: Pereira-da-Conceicoa, L L , Price, Benjamin W , Barber-James, Helen M
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7151 , http://hdl.handle.net/10962/d1011855
- Description: Baetis harrisoni Barnard is a mayfly frequently encountered in river studies across Africa, but the external morphological features used for identifying nymphs have been observed to vary subtly between different geographic locations. It has been associated with a wide range of ecological conditions, including pH extremes of pH 2.9–10.0 in polluted waters. We present a molecular study of the genetic variation within B. harrisoni across 21 rivers in its distribution range in southern Africa.
- Full Text:
- Date Issued: 2012
Evaluation of a service-learning elective as an approach to enhancing the pharmacist's role in health promotion in South Africa
- Srinivas, Sunitha C, Wrench, Wendy W
- Authors: Srinivas, Sunitha C , Wrench, Wendy W
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6443 , http://hdl.handle.net/10962/d1006630
- Description: Background. A service-learning (SL) elective offered to final-year pharmacy students was introduced in 2007. The elective demonstrated a holistic approach to creating opportunities for future pharmacists to understand the current needs and future challenges of the burden of disease in developing countries such as South Africa and to foresee their key roles in health promotion. Methods. The 2007 Sasol National Festival of Science and Technology (SciFest) was chosen as the ideal platform to implement this elective. Evaluation of the elective was carried out in association with the Academic Development Centre using a web-based software tool known as the ADC evaluation assistant (ADCEA). The ADCEA consisted of a ‘question bank’ from which the course facilitators selected nine ranked closed questions as well as two open-ended questions. Results. SciFest participation, in the course of the service-learning elective, was acknowledged by students to have prepared them as responsible citizens to undertake health promotion in the public sector healthcare system. Conclusion. Students’ experiences of the learning opportunities provided in the SciFest elective highlight the strengths of this SL programme.
- Full Text:
- Date Issued: 2012
- Authors: Srinivas, Sunitha C , Wrench, Wendy W
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6443 , http://hdl.handle.net/10962/d1006630
- Description: Background. A service-learning (SL) elective offered to final-year pharmacy students was introduced in 2007. The elective demonstrated a holistic approach to creating opportunities for future pharmacists to understand the current needs and future challenges of the burden of disease in developing countries such as South Africa and to foresee their key roles in health promotion. Methods. The 2007 Sasol National Festival of Science and Technology (SciFest) was chosen as the ideal platform to implement this elective. Evaluation of the elective was carried out in association with the Academic Development Centre using a web-based software tool known as the ADC evaluation assistant (ADCEA). The ADCEA consisted of a ‘question bank’ from which the course facilitators selected nine ranked closed questions as well as two open-ended questions. Results. SciFest participation, in the course of the service-learning elective, was acknowledged by students to have prepared them as responsible citizens to undertake health promotion in the public sector healthcare system. Conclusion. Students’ experiences of the learning opportunities provided in the SciFest elective highlight the strengths of this SL programme.
- Full Text:
- Date Issued: 2012
Graviton n-point functions for UV-complete theories in Anti-de Sitter space
- Authors: Brustein, R , Medved, A J M
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6820 , http://hdl.handle.net/10962/d1004427
- Description: We calculate graviton n-point functions in an anti-de Sitter black brane background for effective gravity theories whose linearized equations of motion have at most two time derivatives. We compare the n-point functions in Einstein gravity to those in theories whose leading correction is quadratic in the Riemann tensor. The comparison is made for any number of gravitons and for all physical graviton modes in a kinematic region for which the leading correction can significantly modify the Einstein result. We find that the n-point functions of Einstein gravity depend on at most a single angle, whereas those of the corrected theories may depend on two angles. For the four-point functions, Einstein gravity exhibits linear dependence on the Mandelstam variable s versus a quadratic dependence on s for the corrected theory.
- Full Text:
- Date Issued: 2012
- Authors: Brustein, R , Medved, A J M
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6820 , http://hdl.handle.net/10962/d1004427
- Description: We calculate graviton n-point functions in an anti-de Sitter black brane background for effective gravity theories whose linearized equations of motion have at most two time derivatives. We compare the n-point functions in Einstein gravity to those in theories whose leading correction is quadratic in the Riemann tensor. The comparison is made for any number of gravitons and for all physical graviton modes in a kinematic region for which the leading correction can significantly modify the Einstein result. We find that the n-point functions of Einstein gravity depend on at most a single angle, whereas those of the corrected theories may depend on two angles. For the four-point functions, Einstein gravity exhibits linear dependence on the Mandelstam variable s versus a quadratic dependence on s for the corrected theory.
- Full Text:
- Date Issued: 2012
In vitro dissolution kinetics of Captopril from microspheres manufactured by solvent evaporation
- Khamanga, Sandile M, Walker, Roderick B
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
- Authors: Khamanga, Sandile M , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6390 , http://hdl.handle.net/10962/d1006311
- Description: The aim of this study was to develop and assess captopril-loaded microspheres in which Methocel and Eudragit RS were used as release-controlling factors and to evaluate captopril (CPT) release using kinetic models. Drug-excipient interactions were evaluated using infrared studies, and the physical appearance was characterized using scanning electron microscopy (SEM). A burst effect was observed during the first stage of dissolution for most batches of microspheres. SEM results reveal that this may be attributed to dissolution of captopril crystals that were present on the surface, embedded in the superficial layer of the matrix materials, trapped near the surface of the microspheres, or that may have diffused rapidly through the porous surface of the capsules. The release data generated during in vitro release studies were fitted to zero-order, first-order, Higuchi, Korsmeyer–Peppas, Kopcha, and Makoid–Banakar models. The release kinetics of captopril from most formulations followed a classical Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores located in the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed a predominance of diffusion relative to swelling or erosion throughout the entire test period. The drug release mechanism was also confirmed by the Makoid–Banakar and Korsmeyer–Peppas model exponents. This further supports a diffusion–release mechanism for most formulations. The models postulate that the total drug released is a summation of several mechanisms (viz., burst release, relaxation-induced controlled release, and diffusional release). These results also support the potential application of Eudragit/Methocel microspheres as a suitable sustained-release drug delivery system for captopril.
- Full Text:
- Date Issued: 2012
Prediction of water temperature metrics using spatial modelling in the Eastern and Western Cape, South Africa
- Rivers-Moore, N A, Mantel, S, Dallas, H F
- Authors: Rivers-Moore, N A , Mantel, S , Dallas, H F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
- Date Issued: 2012
- Authors: Rivers-Moore, N A , Mantel, S , Dallas, H F
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:7071 , http://hdl.handle.net/10962/d1003947 , http://www.scielo.org.za/scielo.php?pid=S1816-79502012000200002&script=sci_arttext
- Description: Key aspects of a river's temperature regime are described by magnitudes, timing and durations of thermal events, and frequencies of extreme exceedance events. To understand alterations to thermal regimes, it is necessary to describe thermal time series based on these statistics. Classification of sites based on their thermal metrics, and understanding of spatial patterns of these thermal statistics, provides a powerful approach for comparing study sites against reference sites. Water temperature regime dynamics should be viewed regionally, where regional divisions have an inherent underpinning by an understanding of natural thermal variability. The aim of this research was to link key water temperature metrics to readily-mapped environmental surrogates, and to produce spatial images of temperature metrics: 37 temperature metrics were derived for 12 months of sub-daily water temperatures at 90 sites in the Eastern Cape and Western Cape provinces, South Africa. These metrics were correlated with 16 environmental variables. Correlations enabled development of multiple regression models which facilitated mapping of temperature metrics over the study area. This approach has the potential to be applied at a national scale as more thermal time series are collected nationally. It is argued that the appropriateness of management decisions in rivers can be improved by including guidelines for thermal metrics at a regional scale. Such maps could facilitate incorporation of a temperature component into management guidelines for water resources.
- Full Text:
- Date Issued: 2012
The use of response surface methodology to evaluate the impact of level 2 SUPAC–IR changes on the in vitro release of metronidazole and ranitidine from a fixed-dose combination tablet
- King’ori, Loti D, Walker, Roderick B
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
- Authors: King’ori, Loti D , Walker, Roderick B
- Date: 2012
- Language: English
- Type: text , Article
- Identifier: vital:6391 , http://hdl.handle.net/10962/d1006313
- Description: The purpose of this study was to evaluate the effect of different levels of disintegrant (croscarmellose sodium, CCS), binder (polyvinylprrolidone K30, PVP–K30), and lubricant (magnesium stearate) on the in vitro release of metronidazole (MTZ) and rantidine (RTD) from a solid oral fixed-dose combination tablet. The excipient levels investigated were Level 2 changes in component and composition described in the Scale-Up and Post Approval Changes for Immediate Release (SUPAC–IR) guidance (1). Batches of tablets (1000 units) were manufactured by wet granulation using a Saral high-shear mixer granulator and a Manesty B3B rotary tablet press. Weight uniformity, friability, and disintegration of all tablets were assessed, and all batches complied with compendial specifications. The amount of drug released (Q) at ten minutes was dependent on the levels of CCS in the formulation, and the effect of PVP–K30 and magnesium stearate was dependent on the levels of CCS. Synergistic interactions between independent variables were observed for the Q10 value for RTD, whereas PVP–K30 and magnesium stearate exhibited an antagonistic effect on the Q10 values for MTZ and RTD. The use of response surface methodology facilitated an investigation into the effect of Level 2 component and composition changes, as described in SUPAC–IR, on the in vitro release of MTZ and RTD from a fixed-dose combination (FDC) solid oral dosage form (SODF).
- Full Text:
- Date Issued: 2012
Three tales of Theal: biography, history and ethnography on the Eastern Frontier
- Authors: Naidu, Samantha
- Date: 2012
- Language: English
- Type: Article , text
- Identifier: vital:24529 , http://hdl.handle.net/10962/36216 , https://www.jstor.org/stable/23267873?seq=1#page_scan_tab_contents , https://orcid.org/0000-0001-9456-8657
- Full Text:
- Date Issued: 2012
- Authors: Naidu, Samantha
- Date: 2012
- Language: English
- Type: Article , text
- Identifier: vital:24529 , http://hdl.handle.net/10962/36216 , https://www.jstor.org/stable/23267873?seq=1#page_scan_tab_contents , https://orcid.org/0000-0001-9456-8657
- Full Text:
- Date Issued: 2012
Western alumnae influencing the world
- Authors: Steyaert, Marcia
- Date: 2012
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7168 , http://hdl.handle.net/10962/d1006069 , Nyokong, Tebello
- Description: In September 2011, IT News Africa, named two Western alumnae, Uche Eze, HBA'06, and Tebello Nyokong, PhD1987 (Chemistry) in their list of top 10 most influential women in science and technology in Africa. Nyokong is a professor of medicinal chemistry and nanotechnology at Rhodes University and is recognized as one of the top three publishing scientists in South Africa.
- Full Text:
- Date Issued: 2012
- Authors: Steyaert, Marcia
- Date: 2012
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7168 , http://hdl.handle.net/10962/d1006069 , Nyokong, Tebello
- Description: In September 2011, IT News Africa, named two Western alumnae, Uche Eze, HBA'06, and Tebello Nyokong, PhD1987 (Chemistry) in their list of top 10 most influential women in science and technology in Africa. Nyokong is a professor of medicinal chemistry and nanotechnology at Rhodes University and is recognized as one of the top three publishing scientists in South Africa.
- Full Text:
- Date Issued: 2012
The Educational Journal
- Date: 2011-09
- Subjects: Education – South Africa , South Africa – Economic conditions , South Africa – Social conditions
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/41687 , vital:36555 , Bulk File 7
- Description: The Educational Journal was the official organ of the Teachers' League of South Africa and focussed on education within the context of a racialized South Africa. From the 2000s, the journal was published by the National Union of Public Service and Allied Workers (NUPSAW), a trade union formed in August 1998 from the amalgamation of militant and moderate trade unions and also operated in the education sphere.
- Full Text: false
- Date Issued: 2011-09
- Date: 2011-09
- Subjects: Education – South Africa , South Africa – Economic conditions , South Africa – Social conditions
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/41687 , vital:36555 , Bulk File 7
- Description: The Educational Journal was the official organ of the Teachers' League of South Africa and focussed on education within the context of a racialized South Africa. From the 2000s, the journal was published by the National Union of Public Service and Allied Workers (NUPSAW), a trade union formed in August 1998 from the amalgamation of militant and moderate trade unions and also operated in the education sphere.
- Full Text: false
- Date Issued: 2011-09
APDUSA Views
- Date: 2011- 06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33536 , vital:32884 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011- 06
- Date: 2011- 06
- Subjects: Government, Resistance to -- South Africa , South Africa -- History -- 20th century , South Africa -- Politics and government
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/10948/33536 , vital:32884 , Bulk File 7
- Description: APDUSA Views was published by the African People’s Democratic Union of Southern Africa (Natal), an affiliate of the New Unity Movement.
- Full Text: false
- Date Issued: 2011- 06
A South African response to ethics in legal education
- Authors: Kruuse, Helen
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54174 , vital:26399 , https://www.routledge.com/The-Ethics-Project-in-Legal-Education/Robertson-Corbin-Tranter-Bartlett/p/book/9780415546515
- Description: The contributions in this volume suggest that "the ethics project in legal education" is increasingly an international one. Even though the strength of commitment by both the profession and the legal academy to "ethics learning" within law schools varies, two fundamental questions confront all who work in this area. First, what is it that we want our students to learn (or, perhaps, in what manner do we want our students to develop) from the teaching of "legal ethics"? Second, how can we create a learning environment that will encourage the nature and quality of learning we think is important?.
- Full Text: false
- Date Issued: 2011
- Authors: Kruuse, Helen
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54174 , vital:26399 , https://www.routledge.com/The-Ethics-Project-in-Legal-Education/Robertson-Corbin-Tranter-Bartlett/p/book/9780415546515
- Description: The contributions in this volume suggest that "the ethics project in legal education" is increasingly an international one. Even though the strength of commitment by both the profession and the legal academy to "ethics learning" within law schools varies, two fundamental questions confront all who work in this area. First, what is it that we want our students to learn (or, perhaps, in what manner do we want our students to develop) from the teaching of "legal ethics"? Second, how can we create a learning environment that will encourage the nature and quality of learning we think is important?.
- Full Text: false
- Date Issued: 2011
Evaluation of the kinetics and mechanism of drug release from Econazole nitrate nanosponge loaded Carbapol Hydrogel
- Sharma, Renuka, Walker, Roderick B, Pathak, Kamla
- Authors: Sharma, Renuka , Walker, Roderick B , Pathak, Kamla
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6437 , http://hdl.handle.net/10962/d1006614
- Description: The objective of this study was to investigate the mechanism of release of econazole nitrate (EN) nanosponges loaded hydrogel and to compare it with EN hydrogel so as to develop an extended release topical drug delivery system of EN. Nanosponges of EN were prepared using ethyl cellulose and PVA by emulsion solvent evaporation method. On the basis of pharmacotechnical evaluation nanosponges with least particle size of 230.1 nm and good rheological properties were formulated as hydrogel (F1 – F7). In vitro drug release data of EN nanosponges loaded hydrogels in phosphate buffer pH 6.8 and 7.4 when analysed by GraphPad Prism software version 4.0 San Diego, USA best fitted the Makoid-2 Banakar model (R value greater than 0.98). The Korsmeyer-Peppas release exponent (n) ranged between 0.331 – 0.418, which confirmed diffusion as the principle mechanism of drug release. The release mechanism was further confirmed by calculating the ratio of exponents A/B ratio derived from the Kopcha model.
- Full Text:
- Date Issued: 2011
- Authors: Sharma, Renuka , Walker, Roderick B , Pathak, Kamla
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6437 , http://hdl.handle.net/10962/d1006614
- Description: The objective of this study was to investigate the mechanism of release of econazole nitrate (EN) nanosponges loaded hydrogel and to compare it with EN hydrogel so as to develop an extended release topical drug delivery system of EN. Nanosponges of EN were prepared using ethyl cellulose and PVA by emulsion solvent evaporation method. On the basis of pharmacotechnical evaluation nanosponges with least particle size of 230.1 nm and good rheological properties were formulated as hydrogel (F1 – F7). In vitro drug release data of EN nanosponges loaded hydrogels in phosphate buffer pH 6.8 and 7.4 when analysed by GraphPad Prism software version 4.0 San Diego, USA best fitted the Makoid-2 Banakar model (R value greater than 0.98). The Korsmeyer-Peppas release exponent (n) ranged between 0.331 – 0.418, which confirmed diffusion as the principle mechanism of drug release. The release mechanism was further confirmed by calculating the ratio of exponents A/B ratio derived from the Kopcha model.
- Full Text:
- Date Issued: 2011
Good Chemistry
- Authors: Grange, Helen
- Date: 2011
- Subjects: Nyokong, Tebello , Africa-Arab State 2009 Unesco-L'Oreal Award for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7185 , http://hdl.handle.net/10962/d1006276 , Nyokong, Tebello , Africa-Arab State 2009 Unesco-L'Oreal Award for Women in Science
- Description: Helen Grange profiles four women who've fearlessly taken on the complex predominantly male-dominated field of science.
- Full Text:
- Date Issued: 2011
- Authors: Grange, Helen
- Date: 2011
- Subjects: Nyokong, Tebello , Africa-Arab State 2009 Unesco-L'Oreal Award for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7185 , http://hdl.handle.net/10962/d1006276 , Nyokong, Tebello , Africa-Arab State 2009 Unesco-L'Oreal Award for Women in Science
- Description: Helen Grange profiles four women who've fearlessly taken on the complex predominantly male-dominated field of science.
- Full Text:
- Date Issued: 2011
I love laser : it's my guiding light
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7184 , http://hdl.handle.net/10962/d1006274 , http://unesdoc.unesco.org/images/0019/001906/190645e.pdf#190680 , Nyokong, Tebello
- Description: What is the common thread that could possibly link denim jeans, cancer and pesticides? None is evident. Yet when South African chemist Tebello Nyokong describes her fascinating research, the link that emerges is light. Nyokong, a specialist in nanochemistry, loves laser, and is using it in ways that could have a revolutionary impact on medicine and the environment.
- Full Text:
- Date Issued: 2011
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7184 , http://hdl.handle.net/10962/d1006274 , http://unesdoc.unesco.org/images/0019/001906/190645e.pdf#190680 , Nyokong, Tebello
- Description: What is the common thread that could possibly link denim jeans, cancer and pesticides? None is evident. Yet when South African chemist Tebello Nyokong describes her fascinating research, the link that emerges is light. Nyokong, a specialist in nanochemistry, loves laser, and is using it in ways that could have a revolutionary impact on medicine and the environment.
- Full Text:
- Date Issued: 2011
Non-perturbative unitarity constraints on the ratio of shear viscosity to entropy density in ultraviolet-complete theories with a gravity dual
- Authors: Brustein, R , Medved, A J M
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6817 , http://hdl.handle.net/10962/d1004327
- Description: We reconsider, from a novel perspective, how unitarity constrains the corrections to the ratio of shear viscosity η to entropy density s. We start with higher-derivative extensions of Einstein gravity in asymptotically anti-de Sitter spacetimes. It is assumed that these theories are derived from string theory and thus have a unitary UV completion that is dual to a unitary, UV-complete boundary gauge theory. We then propose that the gravitational perturbations about a solution of the UV-complete theory are described by an effective theory whose linearized equations of motion have at most two time derivatives. Our proposal leads to a concrete prescription for the calculation of η/s for theories of gravity with arbitrary higher-derivative corrections. The resulting ratio can take on values above or below 1/4π and is consistent with all the previous calculations, even though our reasoning is substantially different. For the purpose of calculating η/s, our proposal also leads to only two possible candidates for the effective two-derivative theory: Einstein and Gauss-Bonnet gravity. The distinction between the two is that Einstein gravity satisfies the equivalence principle, and so its graviton correlation functions are polarization-independent, whereas the Gauss-Bonnet theory has polarization-dependent correlation functions. We discuss the graviton three-point functions in this context and explain how these can provide additional information on the value of η/s.
- Full Text:
- Date Issued: 2011
- Authors: Brustein, R , Medved, A J M
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6817 , http://hdl.handle.net/10962/d1004327
- Description: We reconsider, from a novel perspective, how unitarity constrains the corrections to the ratio of shear viscosity η to entropy density s. We start with higher-derivative extensions of Einstein gravity in asymptotically anti-de Sitter spacetimes. It is assumed that these theories are derived from string theory and thus have a unitary UV completion that is dual to a unitary, UV-complete boundary gauge theory. We then propose that the gravitational perturbations about a solution of the UV-complete theory are described by an effective theory whose linearized equations of motion have at most two time derivatives. Our proposal leads to a concrete prescription for the calculation of η/s for theories of gravity with arbitrary higher-derivative corrections. The resulting ratio can take on values above or below 1/4π and is consistent with all the previous calculations, even though our reasoning is substantially different. For the purpose of calculating η/s, our proposal also leads to only two possible candidates for the effective two-derivative theory: Einstein and Gauss-Bonnet gravity. The distinction between the two is that Einstein gravity satisfies the equivalence principle, and so its graviton correlation functions are polarization-independent, whereas the Gauss-Bonnet theory has polarization-dependent correlation functions. We discuss the graviton three-point functions in this context and explain how these can provide additional information on the value of η/s.
- Full Text:
- Date Issued: 2011
Prof Nyokong receives another Science award
- Authors: Matiwana, Zamuxolo
- Date: 2011
- Subjects: Nyokong, Tebello , International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM)
- Language: English
- Type: Article , text
- Identifier: vital:7182 , http://hdl.handle.net/10962/d1006267 , Nyokong, Tebello
- Description: The Rhodes University professor of Medicinal Chemistry and Nanotechnology, Tebello Nyokong, says the Award for her Scientific Achievements by the International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM) is an honour, especially since it is awarded in memory of the centenary of the first Nobel Prize in Chemistry awarded to a woman: Marie Curie.
- Full Text:
- Date Issued: 2011
- Authors: Matiwana, Zamuxolo
- Date: 2011
- Subjects: Nyokong, Tebello , International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM)
- Language: English
- Type: Article , text
- Identifier: vital:7182 , http://hdl.handle.net/10962/d1006267 , Nyokong, Tebello
- Description: The Rhodes University professor of Medicinal Chemistry and Nanotechnology, Tebello Nyokong, says the Award for her Scientific Achievements by the International Conference on Frontiers of Polymers and Advanced Materiel (ICFPAM) is an honour, especially since it is awarded in memory of the centenary of the first Nobel Prize in Chemistry awarded to a woman: Marie Curie.
- Full Text:
- Date Issued: 2011
Tebello Nyokong "As chemists, we are designers"
- Authors: Nolan, Cathy
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: vital:7201 , http://hdl.handle.net/10962/d1006385
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification.
- Full Text:
- Date Issued: 2011
- Authors: Nolan, Cathy
- Date: 2011
- Language: English
- Type: Article , text
- Identifier: vital:7201 , http://hdl.handle.net/10962/d1006385
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification.
- Full Text:
- Date Issued: 2011
Tebello Nyokong 'As chemists, we are designers'
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7183 , http://hdl.handle.net/10962/d1006272 , Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification. Born in Lesotho, Tebello Nyokong is Professor of Medicinal Chemistry and Nanotechnology at Rhodes University in South Africa and Director of the Nanotechnology Innovation Centre for Sensors (Mintek). In 2009, she was one of the five Laureates of the 2009 L’Oreal–UNESCO Awards for Women in Science.
- Full Text:
- Date Issued: 2011
- Authors: Nolan, Cathy
- Date: 2011
- Subjects: Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Language: English
- Type: Article , text
- Identifier: vital:7183 , http://hdl.handle.net/10962/d1006272 , Nyokong, Tebello , L’Oreal–UNESCO Awards for Women in Science
- Description: What is the common thread running through denim jeans, cancer and pesticides? None springs to mind, yet when chemist Tebello Nyokong describes her fascinating research, a link begins to emerge: light. A specialist in nanochemistry, Nyokong is using laser in ways that could revolutionize not only the diagnosis and treatment of cancer but also water purification. Born in Lesotho, Tebello Nyokong is Professor of Medicinal Chemistry and Nanotechnology at Rhodes University in South Africa and Director of the Nanotechnology Innovation Centre for Sensors (Mintek). In 2009, she was one of the five Laureates of the 2009 L’Oreal–UNESCO Awards for Women in Science.
- Full Text:
- Date Issued: 2011
Unitarity constraints on the ratio of shear viscosity to entropy density in higher derivative gravity
- Authors: Brustein, R , Medved, A J M
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6815 , http://hdl.handle.net/10962/d1004325
- Description: We discuss corrections to the ratio of shear viscosity to entropy density η/s in higher-derivative gravity theories. Generically, these theories contain ghost modes with Planck-scale masses. Motivated by general considerations about unitarity, we propose new boundary conditions for the equations of motion of the graviton perturbations that force the amplitude of the ghosts modes to vanish. We analyze explicitly four-derivative perturbative corrections to Einstein gravity which generically lead to four-derivative equations of motion, compare our choice of boundary conditions to previous proposals and show that, with our new prescription, the ratio η/s remains at the Einstein-gravity value of 1/4π to leading order in the corrections. It is argued that, when the new boundary conditions are imposed on six and higher-derivative equations of motion, η/s can only increase from the Einstein-gravity value. We also recall some general arguments that support the validity of our results to all orders in the strength of the corrections to Einstein gravity. We then discuss the particular case of Gauss-Bonnet gravity, for which the equations of motion are only of two-derivative order and the value of η/s can decrease below 1/4π when treated in a nonperturbative way. Our findings provide further evidence for the validity of the KSS bound for theories that can be viewed as perturbative corrections to Einstein gravity.
- Full Text:
- Date Issued: 2011
- Authors: Brustein, R , Medved, A J M
- Date: 2011
- Language: English
- Type: text , Article
- Identifier: vital:6815 , http://hdl.handle.net/10962/d1004325
- Description: We discuss corrections to the ratio of shear viscosity to entropy density η/s in higher-derivative gravity theories. Generically, these theories contain ghost modes with Planck-scale masses. Motivated by general considerations about unitarity, we propose new boundary conditions for the equations of motion of the graviton perturbations that force the amplitude of the ghosts modes to vanish. We analyze explicitly four-derivative perturbative corrections to Einstein gravity which generically lead to four-derivative equations of motion, compare our choice of boundary conditions to previous proposals and show that, with our new prescription, the ratio η/s remains at the Einstein-gravity value of 1/4π to leading order in the corrections. It is argued that, when the new boundary conditions are imposed on six and higher-derivative equations of motion, η/s can only increase from the Einstein-gravity value. We also recall some general arguments that support the validity of our results to all orders in the strength of the corrections to Einstein gravity. We then discuss the particular case of Gauss-Bonnet gravity, for which the equations of motion are only of two-derivative order and the value of η/s can decrease below 1/4π when treated in a nonperturbative way. Our findings provide further evidence for the validity of the KSS bound for theories that can be viewed as perturbative corrections to Einstein gravity.
- Full Text:
- Date Issued: 2011
A South African response to ethics in legal education
- Authors: Kruuse, Helen
- Date: 2010
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54201 , vital:26403 , https://www.lehmanns.de/shop/recht-steuern/17056480-9780195985818-the-law-of-persons-in-south-africa?PHPSESSID=ogicv1k4dkbpi03lq53elurqh2
- Description: This book reflects the legislative change and consequent changes in common law that fundamentally affect the law of persons, in particular the Children's Act of 2007 and the application of the constitution.
- Full Text: false
- Date Issued: 2010
- Authors: Kruuse, Helen
- Date: 2010
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54201 , vital:26403 , https://www.lehmanns.de/shop/recht-steuern/17056480-9780195985818-the-law-of-persons-in-south-africa?PHPSESSID=ogicv1k4dkbpi03lq53elurqh2
- Description: This book reflects the legislative change and consequent changes in common law that fundamentally affect the law of persons, in particular the Children's Act of 2007 and the application of the constitution.
- Full Text: false
- Date Issued: 2010