A tale of two neglected systems-structure and function of the thin- and thick-walled sieve tubes in monocotyledonous leaves
- Authors: Botha, Christiaan E J
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:6499 , http://hdl.handle.net/10962/d1004514 , http://dx.doi.org/10.3389/fpls.2013.00297
- Description: There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer.
- Full Text:
- Authors: Botha, Christiaan E J
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:6499 , http://hdl.handle.net/10962/d1004514 , http://dx.doi.org/10.3389/fpls.2013.00297
- Description: There is a large body of information relating to the ontogeny, development and the vasculature of eudicotyledonous leaves. However, there is less information available concerning the vascular anatomy of monocotyledonous leaves. This is surprising, given that there are two uniquely different phloem systems present in large groups such as grasses and sedges. Monocotyledonous leaves contain marginal, large, intermediate, and small longitudinal veins that are interconnected by numerous transverse veins. The longitudinal veins contain two metaphloem sieve tube types, which, based upon their ontogeny and position within the phloem, are termed early (thin-walled) and late (thick-walled) sieve tubes. Early metaphloem comprises sieve tubes, companion cells and vascular parenchyma (VP) cells, whilst the late metaphloem, contains thick-walled sieve tubes (TSTs) that lack companion cells. TSTs are generally adjacent to, or no more than one cell removed from the metaxylem. Unlike thin-walled sieve tube (ST) -companion cell complexes, TSTs are connected to parenchyma by pore-plasmodesma units and are generally symplasmically isolated from the STs. This paper addresses key structural and functional differences between thin- and thick-walled sieve tubes and explores the unique advantages of alternate transport strategies that this 5–7 million years old dual system may offer. It would seem that these two systems may enhance, add to, or play a significant role in increasing the efficiency of solute retrieval as well as of assimilate transfer.
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Curriculum Vitae of Prof Tebello Nyokong (OMB)
- Authors: Nyokong, Tebello
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:7233 , http://hdl.handle.net/10962/d1006180
- Description: Department of Science and Technology (DST) and National Research Foundation (NRF) Professor of Medicinal Chemistry and Nanotechnology and Distinguished Professor of Chemistry at Rhodes University.
- Full Text:
- Authors: Nyokong, Tebello
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:7233 , http://hdl.handle.net/10962/d1006180
- Description: Department of Science and Technology (DST) and National Research Foundation (NRF) Professor of Medicinal Chemistry and Nanotechnology and Distinguished Professor of Chemistry at Rhodes University.
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Form over function? The practical application of the Recognition of Customary Marriages Act 1998 in South Africa
- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54094 , vital:26389 , http://journals.co.za/content/ju_jur/2013/1/EJC148455
- Description: The Recognition of Customary Marriages Act 120 of 1998 is a major legislative measure for the development of customary marriages in line with the constitutional principle of equality, specifically for women. The article explores the interactions between this ideal in the Act with empirical observations and the latest judicial decisions concerning its application. It considers various examples of the lack of protection of women in relationships of a customary nature, and it concludes that both the state and courts favour a formal or definitional approach to customary marriage. In considering alternative approaches that could adequately protect vulnerable parties, two conclusions emerge: First, the article recommends a wholesale revision of the South African family law approach from a focus on form to dependency. Second (and as a short-term measure), the article advocates for the putative marriage doctrine to be applied in the customary marriage context to protect many women who are denied access to 'customary marriage' as a form, and as a result, all of the benefits that flow from such marriage.
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- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54094 , vital:26389 , http://journals.co.za/content/ju_jur/2013/1/EJC148455
- Description: The Recognition of Customary Marriages Act 120 of 1998 is a major legislative measure for the development of customary marriages in line with the constitutional principle of equality, specifically for women. The article explores the interactions between this ideal in the Act with empirical observations and the latest judicial decisions concerning its application. It considers various examples of the lack of protection of women in relationships of a customary nature, and it concludes that both the state and courts favour a formal or definitional approach to customary marriage. In considering alternative approaches that could adequately protect vulnerable parties, two conclusions emerge: First, the article recommends a wholesale revision of the South African family law approach from a focus on form to dependency. Second (and as a short-term measure), the article advocates for the putative marriage doctrine to be applied in the customary marriage context to protect many women who are denied access to 'customary marriage' as a form, and as a result, all of the benefits that flow from such marriage.
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Graviton multipoint functions at the AdS boundary
- Authors: Brustein, R , Medved, A J M
- Date: 2013
- Language: English
- Type: text , Article
- Identifier: vital:6819 , http://hdl.handle.net/10962/d1004425
- Description: The gauge-gravity duality can be used to relate connected multipoint graviton functions to connected multipoint correlation functions of the stress tensor of a strongly coupled fluid. Here, we show how to construct the connected graviton functions for a particular kinematic regime that is ideal for discriminating between different gravitational theories, in particular between Einstein theory and its leading-order string theory correction. Our analysis begins with the one-particle irreducible graviton amplitudes in an anti-de Sitter black brane background.We show how these can be used to calculate the connected graviton functions and demonstrate that the two types of amplitudes agree in some cases. It is then asserted on physical grounds that this agreement persists in all cases for both Einstein gravity and its leading-order correction. This outcome implies that the corresponding field-theory correlation functions can be read off directly from the bulk Lagrangian, just as can be done for the ratio of the shear viscosity to the entropy density.
- Full Text:
- Authors: Brustein, R , Medved, A J M
- Date: 2013
- Language: English
- Type: text , Article
- Identifier: vital:6819 , http://hdl.handle.net/10962/d1004425
- Description: The gauge-gravity duality can be used to relate connected multipoint graviton functions to connected multipoint correlation functions of the stress tensor of a strongly coupled fluid. Here, we show how to construct the connected graviton functions for a particular kinematic regime that is ideal for discriminating between different gravitational theories, in particular between Einstein theory and its leading-order string theory correction. Our analysis begins with the one-particle irreducible graviton amplitudes in an anti-de Sitter black brane background.We show how these can be used to calculate the connected graviton functions and demonstrate that the two types of amplitudes agree in some cases. It is then asserted on physical grounds that this agreement persists in all cases for both Einstein gravity and its leading-order correction. This outcome implies that the corresponding field-theory correlation functions can be read off directly from the bulk Lagrangian, just as can be done for the ratio of the shear viscosity to the entropy density.
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Obituary: John Mayne English 1922-2013
- Authors: Lewis, Colin A
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:6162 , http://hdl.handle.net/10962/d1004782
- Description: In 1962 John moved south to Johannesburg, but that bustling city held few attractions for him and he moved further south, to the cathedral city of Grahamstown. Grahamstown, with its nineteenth century Gothic cathedral, elegant Georgian buildings, and distinctive grandeur of Rhodes University, St Andrew's College and other buildings designed by Herbert Baker and his colleagues, suited John. He particularly enjoyed the academic, social, artistic and dramatic life of the community, where many older members of society were distinguished old-Africa hands. John thoroughly enjoyed Grahamstown where, in the partnership of Hoskins and English, he made his mark in the restoration and extension of many significant buildings. His addition to the Anglican chapel at Hog's Back is a masterpiece, as is his incorporation of the old fayade into the rebuilding and extension of the Magistrates' Court.
- Full Text:
- Authors: Lewis, Colin A
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:6162 , http://hdl.handle.net/10962/d1004782
- Description: In 1962 John moved south to Johannesburg, but that bustling city held few attractions for him and he moved further south, to the cathedral city of Grahamstown. Grahamstown, with its nineteenth century Gothic cathedral, elegant Georgian buildings, and distinctive grandeur of Rhodes University, St Andrew's College and other buildings designed by Herbert Baker and his colleagues, suited John. He particularly enjoyed the academic, social, artistic and dramatic life of the community, where many older members of society were distinguished old-Africa hands. John thoroughly enjoyed Grahamstown where, in the partnership of Hoskins and English, he made his mark in the restoration and extension of many significant buildings. His addition to the Anglican chapel at Hog's Back is a masterpiece, as is his incorporation of the old fayade into the rebuilding and extension of the Magistrates' Court.
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Prof Nyokong wins NRF Lifetime Achievement Award
- Date: 2013
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7215 , http://hdl.handle.net/10962/d1006511 , Nyokong, Tebello
- Description: Professor Tebello Nyokong of Rhodes University was presented with the Lifetime Achievement Award at this year’s NRF Awards, held in Port Elizabeth, 2013. She is currently a Distinguished Professor of Chemistry at Rhodes University and holder of the DST-NRF Research Chair in Medicinal Chemistry and Nanotechnology, as well as Director of the DST-Mintek Nanotechnology Innovation Centre focussing on sensors.
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- Date: 2013
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7215 , http://hdl.handle.net/10962/d1006511 , Nyokong, Tebello
- Description: Professor Tebello Nyokong of Rhodes University was presented with the Lifetime Achievement Award at this year’s NRF Awards, held in Port Elizabeth, 2013. She is currently a Distinguished Professor of Chemistry at Rhodes University and holder of the DST-NRF Research Chair in Medicinal Chemistry and Nanotechnology, as well as Director of the DST-Mintek Nanotechnology Innovation Centre focussing on sensors.
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Vrou is gif : the representation of violence against women in Margie Orford’s Clare Hart novels
- Authors: Naidu, Samantha
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:26372 , http://hdl.handle.net/10962/53997 , https://www.ajol.info/index.php/asp/article/view/136092 , https://orcid.org/0000-0001-9456-8657
- Description: This article takes as its starting point that crime fiction is a public and political response to gender-based violence. Using the methods of both discourse analysis and literary analysis of the crime fiction genre, the novels of Margie Orford, internationally acclaimed crime author and patron of Rape Crisis, are examined for their representations of violence against women, and the role played by these representations in Orford’s overall feminist project in the Clare Hart series. The article also considers theories about gender-based violence which link male violence to a purported crisis in the established gender order of South Africa. An attempt is made to understand the relationship between fictionalised representations of violence and the ‘banality’ of real-life violence. Finally, Hart, Orford’s hard-boiled female detective figure, is assessed to determine whether this character constitutes a significant feminist achievement that contributes to discourses which counter gender-based violence
- Full Text: false
- Authors: Naidu, Samantha
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: vital:26372 , http://hdl.handle.net/10962/53997 , https://www.ajol.info/index.php/asp/article/view/136092 , https://orcid.org/0000-0001-9456-8657
- Description: This article takes as its starting point that crime fiction is a public and political response to gender-based violence. Using the methods of both discourse analysis and literary analysis of the crime fiction genre, the novels of Margie Orford, internationally acclaimed crime author and patron of Rape Crisis, are examined for their representations of violence against women, and the role played by these representations in Orford’s overall feminist project in the Clare Hart series. The article also considers theories about gender-based violence which link male violence to a purported crisis in the established gender order of South Africa. An attempt is made to understand the relationship between fictionalised representations of violence and the ‘banality’ of real-life violence. Finally, Hart, Orford’s hard-boiled female detective figure, is assessed to determine whether this character constitutes a significant feminist achievement that contributes to discourses which counter gender-based violence
- Full Text: false
You reap what you sow : regulating marriages and intimate partnerships in a diverse post-apartheid society
- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54152 , vital:26396 , https://tinyurl.com/yaughtn2
- Description: South Africa does not have a particularly proud history. Marred by the politics of separate but (un)equal treatment of its people, the country's past political system has had a damaging effect in all spheres, but specifically on that of the family. In the context of relationships, it is fair to say that the apartheid system was replicated in family law, with the Western 'white' monogamous marriage receiving the state's stamp of approval - leaving other relationships (customary, Muslim, homosexual, cohabiting etc) largely out in the cold.
- Full Text:
- Authors: Kruuse, Helen
- Date: 2013
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54152 , vital:26396 , https://tinyurl.com/yaughtn2
- Description: South Africa does not have a particularly proud history. Marred by the politics of separate but (un)equal treatment of its people, the country's past political system has had a damaging effect in all spheres, but specifically on that of the family. In the context of relationships, it is fair to say that the apartheid system was replicated in family law, with the Western 'white' monogamous marriage receiving the state's stamp of approval - leaving other relationships (customary, Muslim, homosexual, cohabiting etc) largely out in the cold.
- Full Text:
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