Crystallographic Analysis and Structural Revision of a Spiroterpenoid Rearrangement Product
- Lobb, Kevin A, Kaye, Perry T
- Authors: Lobb, Kevin A , Kaye, Perry T
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449335 , vital:74812 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/122435"
- Description: Single crystal X-ray analysis of a spiroterpenoid rearrangement product has revealed that its structure is, in fact, isomeric with the structure proposed previously – an observation that has significant mechanistic implications.
- Full Text:
- Date Issued: 2003
- Authors: Lobb, Kevin A , Kaye, Perry T
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/449335 , vital:74812 , xlink:href="https://www.ajol.info/index.php/sajc/article/view/122435"
- Description: Single crystal X-ray analysis of a spiroterpenoid rearrangement product has revealed that its structure is, in fact, isomeric with the structure proposed previously – an observation that has significant mechanistic implications.
- Full Text:
- Date Issued: 2003
Cyber crime affecting some businesses in South Africa
- Authors: Herselman, Martha Elizabeth
- Date: 2003
- Subjects: Computer crimes , Business enterprises -- South Africa
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10793 , http://hdl.handle.net/10948/212 , Computer crimes , Business enterprises -- South Africa
- Description: This study shows that cyber crime is a recent addition to the list of crimes that can adversely affect businesses directly of indirectly. This phenomenon was not directly prosecutable in South Africa until the enactment of the ECT Act in July 2002. However this Act also prevents businesses to fully prosecute a hacker due to incompleteness. Any kind of commercially related crime can be duplicated as cyber crime. Therefore very little research appears or has been documented about cyber crime in South African companies before 2003.11.21 The motivation to do this study was that businesses often loose millions in cyber attacks, not necessarily through direct theft but by the loss of service and damage to the image of the company. Most of the companies that were approached for interviews on cyber crime were reluctant to share the fact that they were hacked or that cyber crime occurred at their company as it violates their security policies and may expose their fragile security platforms. The purpose of this study was to attempt to get an overall view on how South African businesses are affected by cyber crime in the banking and short term insurance sector of the South African industry and also to determine what legislation exist in this country to protect them. The case study approach was used to determine the affect of cyber crime on businesses like banks and insurance companies. Each case was interviewed, monitored and was observed over a period of a year. This study discloses the evaluation of the results of how cyber crime affected the cases, which were part of this study. The banks felt that they were at an increased risk both externally and internally, which is likely to increase as the migration towards electronic commerce occurs. The insurance industry felt that they are not yet affected by external cyber crime attacks in this country.
- Full Text:
- Date Issued: 2003
- Authors: Herselman, Martha Elizabeth
- Date: 2003
- Subjects: Computer crimes , Business enterprises -- South Africa
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10793 , http://hdl.handle.net/10948/212 , Computer crimes , Business enterprises -- South Africa
- Description: This study shows that cyber crime is a recent addition to the list of crimes that can adversely affect businesses directly of indirectly. This phenomenon was not directly prosecutable in South Africa until the enactment of the ECT Act in July 2002. However this Act also prevents businesses to fully prosecute a hacker due to incompleteness. Any kind of commercially related crime can be duplicated as cyber crime. Therefore very little research appears or has been documented about cyber crime in South African companies before 2003.11.21 The motivation to do this study was that businesses often loose millions in cyber attacks, not necessarily through direct theft but by the loss of service and damage to the image of the company. Most of the companies that were approached for interviews on cyber crime were reluctant to share the fact that they were hacked or that cyber crime occurred at their company as it violates their security policies and may expose their fragile security platforms. The purpose of this study was to attempt to get an overall view on how South African businesses are affected by cyber crime in the banking and short term insurance sector of the South African industry and also to determine what legislation exist in this country to protect them. The case study approach was used to determine the affect of cyber crime on businesses like banks and insurance companies. Each case was interviewed, monitored and was observed over a period of a year. This study discloses the evaluation of the results of how cyber crime affected the cases, which were part of this study. The banks felt that they were at an increased risk both externally and internally, which is likely to increase as the migration towards electronic commerce occurs. The insurance industry felt that they are not yet affected by external cyber crime attacks in this country.
- Full Text:
- Date Issued: 2003
Cyclodepsipeptides from a Kenyan marine cyanobacterium
- Authors: Dzeha, Thomas Mwambire
- Date: 2003
- Subjects: Cyanobacteria , Stereochemistry , Natural products -- Kenya
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4303 , http://hdl.handle.net/10962/d1004961 , Cyanobacteria , Stereochemistry , Natural products -- Kenya
- Description: An examination of an organic extract of the cyanobacterium Lyngbya majuscula collected from Wasini Island off the southern Kenyan coast led to the isolation of the known cyclodepsipeptide antanapeptin A (7), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclodepsipeptide, homodolastatin 16 (42). Although L. majuscula is a common, pantropical cyanobacterium this study represents the first investigation of the natural product chemistry of a Kenyan population of L. majuscula. The structures of the two cyclodepsipeptides were determined from 2D NMR and mass spectrometry data. The L- stereochemistry of the proline, valine, and N-methylphenylalanine amino acids in 7 and the L – proline configuration in 42, was confirmed by Marfey’s HPLC method. Chiral GC was used to determine the absolute stereochemistry of the hydroxyisovaleric acid moiety in 7 and 42, the lactate residue in 42 and tentatively propose an L-stereochemistry for the Nmethylisoleucine amino acid in 42. Homodolastatin 16, a higher homologue of the potential anti-cancer agent, dolastatin 16, exhibited moderate activity against two oesophageal cancer cell lines.
- Full Text:
- Date Issued: 2003
- Authors: Dzeha, Thomas Mwambire
- Date: 2003
- Subjects: Cyanobacteria , Stereochemistry , Natural products -- Kenya
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4303 , http://hdl.handle.net/10962/d1004961 , Cyanobacteria , Stereochemistry , Natural products -- Kenya
- Description: An examination of an organic extract of the cyanobacterium Lyngbya majuscula collected from Wasini Island off the southern Kenyan coast led to the isolation of the known cyclodepsipeptide antanapeptin A (7), recently isolated from a Madagascan collection of L. majuscula, and a new bioactive cyclodepsipeptide, homodolastatin 16 (42). Although L. majuscula is a common, pantropical cyanobacterium this study represents the first investigation of the natural product chemistry of a Kenyan population of L. majuscula. The structures of the two cyclodepsipeptides were determined from 2D NMR and mass spectrometry data. The L- stereochemistry of the proline, valine, and N-methylphenylalanine amino acids in 7 and the L – proline configuration in 42, was confirmed by Marfey’s HPLC method. Chiral GC was used to determine the absolute stereochemistry of the hydroxyisovaleric acid moiety in 7 and 42, the lactate residue in 42 and tentatively propose an L-stereochemistry for the Nmethylisoleucine amino acid in 42. Homodolastatin 16, a higher homologue of the potential anti-cancer agent, dolastatin 16, exhibited moderate activity against two oesophageal cancer cell lines.
- Full Text:
- Date Issued: 2003
Design and development of a remote reconfigurable internet embedded I/O controller
- Authors: Phillips, Grant
- Date: 2003
- Subjects: Embedded computer systems -- Design and construction , Computer input-output equipment , Programmable controllers , Electronic controllers -- Design and construction
- Language: English
- Type: Thesis , Masters , MTech (Electrical Engineering)
- Identifier: vital:10817 , http://hdl.handle.net/10948/116 , Embedded computer systems -- Design and construction , Computer input-output equipment , Programmable controllers , Electronic controllers -- Design and construction
- Description: The use of embedded Internet systems is growing rapidly in the manufacturing sector. These systems allow the monitoring and controlling of plant machinery and manufactured items from a remote location via a standard Web interface. In a manufacturing environment, it is inevitable that long running processes will require support for dynamic reconfiguration because, for example, machines may fail, services may be moved or withdrawn and user requirements may change. In such an environment it is essential that the operation and architecture of such processes can be modified to reflect such changes. This research project will present methods and ideas for establishing a reconfigurable remote system by using standard 8-bit microcontrollers and reconfigurable hardware. It will allow a manufacturing process to be modified and changed within minutes without even having to be physically present at the location where the process is running.
- Full Text:
- Date Issued: 2003
- Authors: Phillips, Grant
- Date: 2003
- Subjects: Embedded computer systems -- Design and construction , Computer input-output equipment , Programmable controllers , Electronic controllers -- Design and construction
- Language: English
- Type: Thesis , Masters , MTech (Electrical Engineering)
- Identifier: vital:10817 , http://hdl.handle.net/10948/116 , Embedded computer systems -- Design and construction , Computer input-output equipment , Programmable controllers , Electronic controllers -- Design and construction
- Description: The use of embedded Internet systems is growing rapidly in the manufacturing sector. These systems allow the monitoring and controlling of plant machinery and manufactured items from a remote location via a standard Web interface. In a manufacturing environment, it is inevitable that long running processes will require support for dynamic reconfiguration because, for example, machines may fail, services may be moved or withdrawn and user requirements may change. In such an environment it is essential that the operation and architecture of such processes can be modified to reflect such changes. This research project will present methods and ideas for establishing a reconfigurable remote system by using standard 8-bit microcontrollers and reconfigurable hardware. It will allow a manufacturing process to be modified and changed within minutes without even having to be physically present at the location where the process is running.
- Full Text:
- Date Issued: 2003
Development of a language policy in a rural school
- Authors: Fumba, Zamumzi Norman
- Date: 2003
- Subjects: Language policy -- South Africa Language and education -- South Africa Education, Rural -- South Africa -- Peddie Black people -- Education -- South Africa Native language and education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1940 , http://hdl.handle.net/10962/d1007798
- Description: The study was undertaken to observe and participate in the process and development of a language policy for a rural secondary school in Peddie in the Eastern Cape. This was done in collaboration with parents, learners, and teachers. The researcher acted as a researcher, facilitator and learner in the process that Iead to the final product. Twenty four learners were selected from Grade 8 to Grade 10. These learners formed three focus groups. A questionnaire and lesson observation were used to establish what was taking place in the school with regard to language practices and preferences by learners, teachers and parents. Lesson observations were recorded by a tape recorder. Outcomes are that Xhosa is the dominant language to which the learners are exposed. They only have the exposure to 'chunks' of English in class and when they read magazines, newspapers and listening to radio and TV. Teachers code switch. This is supported by both learners and their parents. Parents want their children to improve performance by being taught in the medium of a language they understand well enough. The study shows different perceptions about the language that should be used as LOLT. Parents in the study favour English as LOLT, while parents in general favour Xhosa. This view is also held by both teachers and learners. At a conscious level when teachers and learners talk about the language to be used as LOLT, they favour English, but when they are faced with the reality of the class they are ambivalent, hence they code switch. The study finally reports on the divergent views of the parents, on one hand, and those of the teachers and the learners on the other hand. The divergence will be resolved in a workshop, part of the broader process of school language policy research, which is beyond the scope of the research reported in the thesis. The final product, in the form of the school language policy, will then be drafted for presentation to the School Governing Body (SGB) for ratification and writing up process.
- Full Text:
- Date Issued: 2003
- Authors: Fumba, Zamumzi Norman
- Date: 2003
- Subjects: Language policy -- South Africa Language and education -- South Africa Education, Rural -- South Africa -- Peddie Black people -- Education -- South Africa Native language and education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1940 , http://hdl.handle.net/10962/d1007798
- Description: The study was undertaken to observe and participate in the process and development of a language policy for a rural secondary school in Peddie in the Eastern Cape. This was done in collaboration with parents, learners, and teachers. The researcher acted as a researcher, facilitator and learner in the process that Iead to the final product. Twenty four learners were selected from Grade 8 to Grade 10. These learners formed three focus groups. A questionnaire and lesson observation were used to establish what was taking place in the school with regard to language practices and preferences by learners, teachers and parents. Lesson observations were recorded by a tape recorder. Outcomes are that Xhosa is the dominant language to which the learners are exposed. They only have the exposure to 'chunks' of English in class and when they read magazines, newspapers and listening to radio and TV. Teachers code switch. This is supported by both learners and their parents. Parents want their children to improve performance by being taught in the medium of a language they understand well enough. The study shows different perceptions about the language that should be used as LOLT. Parents in the study favour English as LOLT, while parents in general favour Xhosa. This view is also held by both teachers and learners. At a conscious level when teachers and learners talk about the language to be used as LOLT, they favour English, but when they are faced with the reality of the class they are ambivalent, hence they code switch. The study finally reports on the divergent views of the parents, on one hand, and those of the teachers and the learners on the other hand. The divergence will be resolved in a workshop, part of the broader process of school language policy research, which is beyond the scope of the research reported in the thesis. The final product, in the form of the school language policy, will then be drafted for presentation to the School Governing Body (SGB) for ratification and writing up process.
- Full Text:
- Date Issued: 2003
Development of integrated algal ponding systems in the treatment of wine distillery wastewaters
- Authors: Dekker, Leendert Gideon
- Date: 2003
- Subjects: Sewage -- Purification -- Anaerobic treatment Wine and wine making -- Waste disposal -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4062 , http://hdl.handle.net/10962/d1004530
- Description: In South Africa, wastewater disposal in the wine and distilling industry is undergoing a profound transformation as a result of fundamental changes in regulations and license requirements. To deal with this problem conventional Waste Stabilisation Ponding systems have been used by the industry together with irrigation and evaporation disposal practises. Although effective in the evaporation and containment disposal functions, these pond systems are generally not properly designed and/or managed, resulting in overloading and, at times, the generation of seriously offensive odour problems. Preliminary studies on the feasibility of utilising the Advanced Integrated Wastewater Ponding System as a core treatment technology in winery wastewater treatment were conducted. Results indicated that specific problems had to be addressed before successful ponding treatment could be achieved. This research programme undertook an investigation of the performance of a demonstration ponding system treating household sewage, which formed the basis of the research due to limited experience reported on ponds treating wine industry wastewaters. Malfunctions identified were in correlation with the preliminary winery waste ponding survey, which included unstable fermentation pit functions and inadequate nutrient removal. Retrofitting the fermentation pit with a nylon net across the rising water column resulted in improved retention of active anaerobic sludge, especially during periods of system start-up and/or organic overloading. An investigation into nutrient removal utilising algal biomass provided a valuable contribution towards development of an independent nutrient removal system. Harvested algal biomass was passively manipulated to release polysaccharides under anoxic conditions, with subsequent use as a carbon source by denitrifying organisms. Following denitrification, the still viable algal cells were introduced into a High Rate Algal Pond raceway for photosynthetically produced alkalinity. This high pH environment resulted in induced calcium phosphate mineral formation and subsequent precipitation, as well as effective ammonia stripping from the water. Based on the novel positive research outcomes a decision was made to proceed to the construction of a pilot-scale integrated ponding system treating wastewater from a wine lees factory. The system linked the Anaerobic Baffle Reactor, for pre-treatment, with the improved Advanced Integrated Wastewater Ponding System. The potential of this system has shown that a Waste Stabilisation Ponding system can be engineered to treat wine industry wastewaters and thereby effectively reduce the organic and nutrient loads, by using low-cost retrofitted upgrading unit operations. Valuable algal biomass may also be recovered as a by-product of the treatment process.
- Full Text:
- Date Issued: 2003
- Authors: Dekker, Leendert Gideon
- Date: 2003
- Subjects: Sewage -- Purification -- Anaerobic treatment Wine and wine making -- Waste disposal -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4062 , http://hdl.handle.net/10962/d1004530
- Description: In South Africa, wastewater disposal in the wine and distilling industry is undergoing a profound transformation as a result of fundamental changes in regulations and license requirements. To deal with this problem conventional Waste Stabilisation Ponding systems have been used by the industry together with irrigation and evaporation disposal practises. Although effective in the evaporation and containment disposal functions, these pond systems are generally not properly designed and/or managed, resulting in overloading and, at times, the generation of seriously offensive odour problems. Preliminary studies on the feasibility of utilising the Advanced Integrated Wastewater Ponding System as a core treatment technology in winery wastewater treatment were conducted. Results indicated that specific problems had to be addressed before successful ponding treatment could be achieved. This research programme undertook an investigation of the performance of a demonstration ponding system treating household sewage, which formed the basis of the research due to limited experience reported on ponds treating wine industry wastewaters. Malfunctions identified were in correlation with the preliminary winery waste ponding survey, which included unstable fermentation pit functions and inadequate nutrient removal. Retrofitting the fermentation pit with a nylon net across the rising water column resulted in improved retention of active anaerobic sludge, especially during periods of system start-up and/or organic overloading. An investigation into nutrient removal utilising algal biomass provided a valuable contribution towards development of an independent nutrient removal system. Harvested algal biomass was passively manipulated to release polysaccharides under anoxic conditions, with subsequent use as a carbon source by denitrifying organisms. Following denitrification, the still viable algal cells were introduced into a High Rate Algal Pond raceway for photosynthetically produced alkalinity. This high pH environment resulted in induced calcium phosphate mineral formation and subsequent precipitation, as well as effective ammonia stripping from the water. Based on the novel positive research outcomes a decision was made to proceed to the construction of a pilot-scale integrated ponding system treating wastewater from a wine lees factory. The system linked the Anaerobic Baffle Reactor, for pre-treatment, with the improved Advanced Integrated Wastewater Ponding System. The potential of this system has shown that a Waste Stabilisation Ponding system can be engineered to treat wine industry wastewaters and thereby effectively reduce the organic and nutrient loads, by using low-cost retrofitted upgrading unit operations. Valuable algal biomass may also be recovered as a by-product of the treatment process.
- Full Text:
- Date Issued: 2003
Direct-use value of smallholder crop production in a semi-arid rural South African village
- Dovie, Delali B K, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181595 , vital:43750 , xlink:href="https://doi.org/10.1016/S0308-521X(02)00124-5"
- Description: The monetary value of natural resources used by rural communities for subsistence is important when addressing issues affecting the livelihoods of impoverished rural households. There is therefore the need to attribute monetary values to non-marketed products from smallholder production systems in order to reliably account for resource availability and usage to further sound policy decisions. The objective of this paper is to present an empirical analysis of the direct-use and traded values of crop production by households, and to discuss the implications for policy development. The study was undertaken in combination with an evaluation of other livelihood sectors in Thorndale, a semi-arid rural village in the Limpopo province of South Africa. The net direct-use value of crops was estimated at $443.4 per household per annum across the village. Maize (Zea mays), watermelon (Citrullus, vulgaris), peanuts (Arachis hypogaea) and common beans (Phaseolus vulgaris) contributed over 90% to the total direct-use value of crops. Maize alone contributed 40% of this value per household at an estimated $652/ha. Marketing of resources was not a common practice, limited to only maize and peanuts. Farming was basically a rain-fed–mixed cropping system with low production inputs. Farmer support services, human capital development and tenure security were major areas identified for policy development.
- Full Text:
- Date Issued: 2003
- Authors: Dovie, Delali B K , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181595 , vital:43750 , xlink:href="https://doi.org/10.1016/S0308-521X(02)00124-5"
- Description: The monetary value of natural resources used by rural communities for subsistence is important when addressing issues affecting the livelihoods of impoverished rural households. There is therefore the need to attribute monetary values to non-marketed products from smallholder production systems in order to reliably account for resource availability and usage to further sound policy decisions. The objective of this paper is to present an empirical analysis of the direct-use and traded values of crop production by households, and to discuss the implications for policy development. The study was undertaken in combination with an evaluation of other livelihood sectors in Thorndale, a semi-arid rural village in the Limpopo province of South Africa. The net direct-use value of crops was estimated at $443.4 per household per annum across the village. Maize (Zea mays), watermelon (Citrullus, vulgaris), peanuts (Arachis hypogaea) and common beans (Phaseolus vulgaris) contributed over 90% to the total direct-use value of crops. Maize alone contributed 40% of this value per household at an estimated $652/ha. Marketing of resources was not a common practice, limited to only maize and peanuts. Farming was basically a rain-fed–mixed cropping system with low production inputs. Farmer support services, human capital development and tenure security were major areas identified for policy development.
- Full Text:
- Date Issued: 2003
Disgraceland: history and the humanities in frontier country
- Authors: Cornwell, Gareth D N
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6117 , http://hdl.handle.net/10962/d1004618
- Description: This paper explores the significance of Coetzee's choice of Salem in the Eastern Cape as the (part) setting for his novel Disgrace. A determinedly local and historical reading of the text suggests that Lucy's conduct represents an "ideal" solution to the historical issues of wrong and reparation raised in the novel. This finding is scrutinized through a reading of "The Humanities in Africa" from Elizabeth Costello, and it is concluded that whatever hope for rehabilitation or redemption the novel holds out for white South Africans necessarily exists beyond the discourse of the humanities, indeed, outside of history itself.
- Full Text:
- Date Issued: 2003
- Authors: Cornwell, Gareth D N
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6117 , http://hdl.handle.net/10962/d1004618
- Description: This paper explores the significance of Coetzee's choice of Salem in the Eastern Cape as the (part) setting for his novel Disgrace. A determinedly local and historical reading of the text suggests that Lucy's conduct represents an "ideal" solution to the historical issues of wrong and reparation raised in the novel. This finding is scrutinized through a reading of "The Humanities in Africa" from Elizabeth Costello, and it is concluded that whatever hope for rehabilitation or redemption the novel holds out for white South Africans necessarily exists beyond the discourse of the humanities, indeed, outside of history itself.
- Full Text:
- Date Issued: 2003
Disturbances of attitudes and behaviours related to eating in black and white females at high school and university in South Africa
- Edwards, David J A, d'Agrela, A, Geach, M, Welman, Mark
- Authors: Edwards, David J A , d'Agrela, A , Geach, M , Welman, Mark
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6246 , http://hdl.handle.net/10962/d1007864
- Description: This paper reports two studies, which contribute to the increasing evidence that the attitudes and behaviours associated with eating disorders, are encountered among both black and white females in South Africa. In Study One, the Eating Disorders Inventory EDI was administered to black (n=39) and white (n=41) female students in Natal. There were no significant differences between black and white on the sub-scales which measure disturbed eating behaviour directly (Drive for Thinness, Bulimia, Body Dissatisfaction). However black respondents scrored higher on Perfectionism, Interpersonal Distrust and Maturity Fears, variables believed to predispose individuals to eating disorders. In Study Two, the Bulimia Test (BULIT) was administered to black and white females at three educational levels. There was no significant effect of Ethnicity, but there was a significant effect of Age: Standard 6 respondents had significantly higher scores than University students. In both studies, Body mass index (BMI) was significantly higher among blacks than whites. In Study One there was no significant correlation between BMI and Drive for Thinness in either blacks or whites. However in Study Two, the correlation between BMI and BULIT full scale was significant in the case of both blacks (r = 0,39; p <,01) and whites (r = 0,38; p<,05). These findings are consistent with those of other recent studies, which find disturbances in eating-related attitudes and behaviour in all ethnic groups in South Africa.
- Full Text:
- Date Issued: 2003
- Authors: Edwards, David J A , d'Agrela, A , Geach, M , Welman, Mark
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6246 , http://hdl.handle.net/10962/d1007864
- Description: This paper reports two studies, which contribute to the increasing evidence that the attitudes and behaviours associated with eating disorders, are encountered among both black and white females in South Africa. In Study One, the Eating Disorders Inventory EDI was administered to black (n=39) and white (n=41) female students in Natal. There were no significant differences between black and white on the sub-scales which measure disturbed eating behaviour directly (Drive for Thinness, Bulimia, Body Dissatisfaction). However black respondents scrored higher on Perfectionism, Interpersonal Distrust and Maturity Fears, variables believed to predispose individuals to eating disorders. In Study Two, the Bulimia Test (BULIT) was administered to black and white females at three educational levels. There was no significant effect of Ethnicity, but there was a significant effect of Age: Standard 6 respondents had significantly higher scores than University students. In both studies, Body mass index (BMI) was significantly higher among blacks than whites. In Study One there was no significant correlation between BMI and Drive for Thinness in either blacks or whites. However in Study Two, the correlation between BMI and BULIT full scale was significant in the case of both blacks (r = 0,39; p <,01) and whites (r = 0,38; p<,05). These findings are consistent with those of other recent studies, which find disturbances in eating-related attitudes and behaviour in all ethnic groups in South Africa.
- Full Text:
- Date Issued: 2003
Dynamic run-time application development using CORBA objects and XML in the field of distributed GIS
- Preston, Michael, Clayton, Peter G, Wells, George C
- Authors: Preston, Michael , Clayton, Peter G , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430500 , vital:72695 , https://doi.org/10.1080/1365881021000026557
- Description: The research presented describes our approach to enabling content developers and end-users to create and/or customise distributed GIS applications dynamical-ly at run-time through the incorporation of GIS services, implemented as stand-alone components or CORBA Objects, with a specialised XML descriptor. It also looks at some of the design considerations that must be dealt with by both the client-application developer as well as the service developer, including the GIS service description, associated GUI and help system.
- Full Text:
- Date Issued: 2003
Dynamic run-time application development using CORBA objects and XML in the field of distributed GIS
- Authors: Preston, Michael , Clayton, Peter G , Wells, George C
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430500 , vital:72695 , https://doi.org/10.1080/1365881021000026557
- Description: The research presented describes our approach to enabling content developers and end-users to create and/or customise distributed GIS applications dynamical-ly at run-time through the incorporation of GIS services, implemented as stand-alone components or CORBA Objects, with a specialised XML descriptor. It also looks at some of the design considerations that must be dealt with by both the client-application developer as well as the service developer, including the GIS service description, associated GUI and help system.
- Full Text:
- Date Issued: 2003
Editorial: the policy-in-practice nexus
- Lotz-Sisitka, Heila, Obol, Charles, Nhamo, Godwell
- Authors: Lotz-Sisitka, Heila , Obol, Charles , Nhamo, Godwell
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67389 , vital:29083 , https://www.ajol.info/index.php/sajee/article/view/122661/112205
- Description: publisher version , Environmental policy development and implementation has become a ‘hot topic’ in southern Africa, following global imperatives for countries around the world to articulate their intentions to become more sustainable through public policy. Many policies in the region have been developed with the support of large scale donor funding. Much of the funding is often allocated to policy development processes rather than policy implementation processes, and many countries have experienced ‘gaps’ between policy intention and policy playing out in the field. Recently the Southern African Development Community’s Regional Environmental Education Programme (SADC REEP) appointed an environmental education policy advisor to influence regional policy (our Guest Editor, Charles Obol).This edition of the journal, funded by SADC REEP, aims to provide perspective on the policy-in-practice nexus in southern Africa.
- Full Text:
- Date Issued: 2003
- Authors: Lotz-Sisitka, Heila , Obol, Charles , Nhamo, Godwell
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67389 , vital:29083 , https://www.ajol.info/index.php/sajee/article/view/122661/112205
- Description: publisher version , Environmental policy development and implementation has become a ‘hot topic’ in southern Africa, following global imperatives for countries around the world to articulate their intentions to become more sustainable through public policy. Many policies in the region have been developed with the support of large scale donor funding. Much of the funding is often allocated to policy development processes rather than policy implementation processes, and many countries have experienced ‘gaps’ between policy intention and policy playing out in the field. Recently the Southern African Development Community’s Regional Environmental Education Programme (SADC REEP) appointed an environmental education policy advisor to influence regional policy (our Guest Editor, Charles Obol).This edition of the journal, funded by SADC REEP, aims to provide perspective on the policy-in-practice nexus in southern Africa.
- Full Text:
- Date Issued: 2003
Education, ethics and values : A response to Peter Blaze Corcoran’s keynote address, EEASA 2003
- Authors: van Harmelen, Ursula
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6099 , http://hdl.handle.net/10962/d1008663
- Description: This paper is written in response to the Keynote Adress on the Earth Charter presented by Peter Blaze Corcoran at the EEASA 2003 Conference in Namibia. It draws attention to the significance of ethical debates in education and emphasises the need for careful attention to the way in which educators approach values education. In particular the paper considers the Earth Charter critically, and notes that while there is much value in the principles of the Earth Charter for guiding educational practice, educators should also consider some of the dilemmas of simply appropriating univeral ethical frameworks to guide practice.
- Full Text:
- Date Issued: 2003
- Authors: van Harmelen, Ursula
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6099 , http://hdl.handle.net/10962/d1008663
- Description: This paper is written in response to the Keynote Adress on the Earth Charter presented by Peter Blaze Corcoran at the EEASA 2003 Conference in Namibia. It draws attention to the significance of ethical debates in education and emphasises the need for careful attention to the way in which educators approach values education. In particular the paper considers the Earth Charter critically, and notes that while there is much value in the principles of the Earth Charter for guiding educational practice, educators should also consider some of the dilemmas of simply appropriating univeral ethical frameworks to guide practice.
- Full Text:
- Date Issued: 2003
Effect of photoperiod on sexual development, growth and production of quail (coturnix coturnix japonica)
- Authors: De Jager, Pieter Herodes
- Date: 2003
- Subjects: Quails , Quails -- Growth , Quails -- Effect of light on , Photoperiodism
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10969 , http://hdl.handle.net/10948/227 , Quails , Quails -- Growth , Quails -- Effect of light on , Photoperiodism
- Description: The aim of the study was to determine the effect of photoperiod on production of quail in South Africa. Day old chicks were randomly divided into two groups. One group (n=74) received continuous light (LL) while the other group (n=77) received 13 h of light (LD) per day. Traits measured were sexual characteristics (age at sexual maturity and testis weight, egg production and egg weight) and growth (body weight) development in males and females respectively. Significant differences in growth existed between sexes; females were 171.44±17.15 and 182.91±17.75 g compared to the 151.77±13.20 and 155.00±16.86 g for males in both LL and LD groups respectively. Both males and females in the LL group initially outperformed the LD group in growth rate but, by day 72 the LD group had compensated and were 4.6% heavier than the LL group. A similar trend was observed for sexual maturity between the LL and LD groups. However, photoperiod did significantly influence initial egg production in favour of the LL group. The LL group had 80% of the females in production by day 44 compared to the 60% of the LD group. The initial egg weight of the LL group was 14 % higher than those of the LD group. Quail subjected to continuous light attained earlier sexual maturity and production with lower final weight compared to quail subjected to an intermediate photoperiod. The application of a longer photoperiod would therefore favour an egg production system.
- Full Text:
- Date Issued: 2003
- Authors: De Jager, Pieter Herodes
- Date: 2003
- Subjects: Quails , Quails -- Growth , Quails -- Effect of light on , Photoperiodism
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10969 , http://hdl.handle.net/10948/227 , Quails , Quails -- Growth , Quails -- Effect of light on , Photoperiodism
- Description: The aim of the study was to determine the effect of photoperiod on production of quail in South Africa. Day old chicks were randomly divided into two groups. One group (n=74) received continuous light (LL) while the other group (n=77) received 13 h of light (LD) per day. Traits measured were sexual characteristics (age at sexual maturity and testis weight, egg production and egg weight) and growth (body weight) development in males and females respectively. Significant differences in growth existed between sexes; females were 171.44±17.15 and 182.91±17.75 g compared to the 151.77±13.20 and 155.00±16.86 g for males in both LL and LD groups respectively. Both males and females in the LL group initially outperformed the LD group in growth rate but, by day 72 the LD group had compensated and were 4.6% heavier than the LL group. A similar trend was observed for sexual maturity between the LL and LD groups. However, photoperiod did significantly influence initial egg production in favour of the LL group. The LL group had 80% of the females in production by day 44 compared to the 60% of the LD group. The initial egg weight of the LL group was 14 % higher than those of the LD group. Quail subjected to continuous light attained earlier sexual maturity and production with lower final weight compared to quail subjected to an intermediate photoperiod. The application of a longer photoperiod would therefore favour an egg production system.
- Full Text:
- Date Issued: 2003
Effect of pictograms on readability of patient information materials:
- Mansoor, Leila E, Dowse, Roslind
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157003 , vital:40078 , https://0-doi.org.wam.seals.ac.za/10.1345/aph.1C449
- Description: To design, develop, and evaluate a simple, understandable medicine label and patient information leaflet (PIL) for nystatin suspension, and to assess the effect of incorporating pictograms on understanding in low-literate participants.
- Full Text:
- Date Issued: 2003
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157003 , vital:40078 , https://0-doi.org.wam.seals.ac.za/10.1345/aph.1C449
- Description: To design, develop, and evaluate a simple, understandable medicine label and patient information leaflet (PIL) for nystatin suspension, and to assess the effect of incorporating pictograms on understanding in low-literate participants.
- Full Text:
- Date Issued: 2003
Effects of small-scale water movement on the settlement and growth rates of the brown mussel Perna perna, on the south-east coast of South Africa
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
Effects of sustained Russian wheat aphid (Diuraphis noxia Mordvilko) feeding on leaf blades of wheat (Triticum aestivum L. cv Adamtas)
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
Electrochemical behavior and detection of dopamine and ascorbic acid at an iron (II) tetrasulfophthalocyanine modified carbon paste microelectrode
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
- Date Issued: 2003
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
- Date Issued: 2003
Electrochemical behaviour of thiol-derivatised zinc (II) phthalocyanine complexes and their self-immobilised films at gold electrodes
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
- Full Text:
- Date Issued: 2003
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
- Full Text:
- Date Issued: 2003
Email security policy implementation in multinational organisations with special reference to privacy laws
- Authors: Dixon, Henry George
- Date: 2003
- Subjects: Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10790 , http://hdl.handle.net/10948/229 , Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Description: In 1971, scientist Ray Tomlinson sent what is now considered the first email message. It was considered as “nothing short of revolutionary … deserv[ing] a spot in the list of great communication inventions such as the printing press, telegraph and telephone” (Festa, 2001). Whereas email was first used exclusively in the military (Arpanet) and in academic circles, it has now become almost ubiquitous, used widely for private, as well as for business correspondence. According to a Berkeley study (Berkeley, 2000), there were approximately 440 million corporate and personal [e-] mailboxes worldwide in 2001, of which more than a third was corporate mailboxes. As a result of the extensive use of email in the corporate environment, Information Officers have to ensure that the use of email adds business value. In an “always on” market place, the efficiency, immediacy and cost effectiveness of email communication are immediately evident. A study by Ferris Research, quoted by Nchor (2001), shows that there is “an overall productivity gain of US$9000 per employee as they send and receive emails to get projects done.” However, the use of email in the corporate envi-ronment also poses business risks that need to be uniquely addressed. Among these “key business risks” (Surfcontrol, 2001) are security risks, viruses, legal liability, pro-ductivity loss and bandwidth abuse. To address the risks mentioned above and to protect the business value of email, spe-cific policies have to be implemented that address email usage. Information Security Policies are defined in most corporate environments. In a study done by Elron Soft-ware (2001), 83% of respondents who have abused email have company policies regu-lating email usage. There appears to be a gap between policy conception and policy implementation. Various factors inhibit effective policy implementation – ethical, legal and cultural. The implementation of corporate policy becomes especially complex in multinational environments where differing information law Email usage is ubiquitous in the modern business environment, but few companies adequately manage the risks associated with email.
- Full Text:
- Date Issued: 2003
- Authors: Dixon, Henry George
- Date: 2003
- Subjects: Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10790 , http://hdl.handle.net/10948/229 , Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Description: In 1971, scientist Ray Tomlinson sent what is now considered the first email message. It was considered as “nothing short of revolutionary … deserv[ing] a spot in the list of great communication inventions such as the printing press, telegraph and telephone” (Festa, 2001). Whereas email was first used exclusively in the military (Arpanet) and in academic circles, it has now become almost ubiquitous, used widely for private, as well as for business correspondence. According to a Berkeley study (Berkeley, 2000), there were approximately 440 million corporate and personal [e-] mailboxes worldwide in 2001, of which more than a third was corporate mailboxes. As a result of the extensive use of email in the corporate environment, Information Officers have to ensure that the use of email adds business value. In an “always on” market place, the efficiency, immediacy and cost effectiveness of email communication are immediately evident. A study by Ferris Research, quoted by Nchor (2001), shows that there is “an overall productivity gain of US$9000 per employee as they send and receive emails to get projects done.” However, the use of email in the corporate envi-ronment also poses business risks that need to be uniquely addressed. Among these “key business risks” (Surfcontrol, 2001) are security risks, viruses, legal liability, pro-ductivity loss and bandwidth abuse. To address the risks mentioned above and to protect the business value of email, spe-cific policies have to be implemented that address email usage. Information Security Policies are defined in most corporate environments. In a study done by Elron Soft-ware (2001), 83% of respondents who have abused email have company policies regu-lating email usage. There appears to be a gap between policy conception and policy implementation. Various factors inhibit effective policy implementation – ethical, legal and cultural. The implementation of corporate policy becomes especially complex in multinational environments where differing information law Email usage is ubiquitous in the modern business environment, but few companies adequately manage the risks associated with email.
- Full Text:
- Date Issued: 2003
Endothermy and chorusing behaviour in the African platypleurine cicada Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae)
- Villet, Martin H, Sanborn, Allen F, Phillips, Polly K F
- Authors: Villet, Martin H , Sanborn, Allen F , Phillips, Polly K F
- Date: 2003
- Language: English
- Type: text , Article
- Identifier: vital:6892 , http://hdl.handle.net/10962/d1011652 , http://dx.doi.org/10.1139/z03-119
- Description: Cicadas use acoustic signals to find mates and therefore offer a phylogenetically independent opportunity to test the generality of ideas about acoustic communication that were developed from studies of other animals. Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae) is a forest-dwelling platypleurine cicada that uses its calling song to form choruses and attract mates. Additionally, P. semiclara produces an encounter call that is involved in courtship and also in spacing males within choruses. Males generally call from exposed trunks and branches within the understory but clear of the undergrowth and fight with other males that call within about 50 cm of them. Choruses sing sporadically throughout the day but focus most of their calling activity into half-hour bouts at dawn and dusk. Body size and ambient temperature had no significant effect on spectral or temporal characteristics of the calling song. Body temperature measurements indicate that P. semiclara thermoregulates endothermically, with a body temperature of more than 22 °C above ambient temperature being measured during calling activity at dusk. Such endothermy provides an advantage to the cicadas by allowing them to call during crepuscular hours when atmospheric conditions are most optimal for acoustic communication and predation risks are minimal. Coincidentally, endogenously regulating body temperature allows the temporal characteristics of the call to be unaffected by ambient temperature changes.
- Full Text:
- Date Issued: 2003
- Authors: Villet, Martin H , Sanborn, Allen F , Phillips, Polly K F
- Date: 2003
- Language: English
- Type: text , Article
- Identifier: vital:6892 , http://hdl.handle.net/10962/d1011652 , http://dx.doi.org/10.1139/z03-119
- Description: Cicadas use acoustic signals to find mates and therefore offer a phylogenetically independent opportunity to test the generality of ideas about acoustic communication that were developed from studies of other animals. Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae) is a forest-dwelling platypleurine cicada that uses its calling song to form choruses and attract mates. Additionally, P. semiclara produces an encounter call that is involved in courtship and also in spacing males within choruses. Males generally call from exposed trunks and branches within the understory but clear of the undergrowth and fight with other males that call within about 50 cm of them. Choruses sing sporadically throughout the day but focus most of their calling activity into half-hour bouts at dawn and dusk. Body size and ambient temperature had no significant effect on spectral or temporal characteristics of the calling song. Body temperature measurements indicate that P. semiclara thermoregulates endothermically, with a body temperature of more than 22 °C above ambient temperature being measured during calling activity at dusk. Such endothermy provides an advantage to the cicadas by allowing them to call during crepuscular hours when atmospheric conditions are most optimal for acoustic communication and predation risks are minimal. Coincidentally, endogenously regulating body temperature allows the temporal characteristics of the call to be unaffected by ambient temperature changes.
- Full Text:
- Date Issued: 2003