Design and evaluation of an electrochemical immunosensor for measles serodiagnosis using measles-specific Immunoglobulin G antibodies
- Mashazi, Philani N, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241705 , vital:50962 , xlink:href="https://doi.org/10.1016/j.talanta.2013.06.036"
- Description: The design of electrochemical immunosensors for the detection of measles-specific antibodies is reported. The measles-antigen modified surface was used as an antibody capture surface. The detection of measles-specific IgG antibodies was accomplished using the voltammetric method and horse-radish peroxidase (HRP) labeled secondary antibody (anti-IgG) as a detecting antibody. The potential applications of the designed immunosensor were evaluated in buffer and serum solutions. The immunosensor exhibited good linearity at concentrations less than 100 ng mL−1 with R2=0.997 and the limit of detection of 6.60 ng mL−1 at 3σ. The potential application of the immunosensor was evaluated in the deliberately infected human and newborn calf serum samples with measles-IgG antibody mimicking real-life samples. The designed electrochemical immunosensor could differentiate between infected and un-infected serum samples as higher catalytic currents were obtained for infected serum samples.
- Full Text:
- Date Issued: 2013
Design of Realistic Hybrid Marine Resource Management Programs in Oceania
- Aswani, Shankar, Ruddle, Kenneth
- Authors: Aswani, Shankar , Ruddle, Kenneth
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422721 , vital:71972 , xlink:href="https://doi.org/10.2984/67.3.11"
- Description: This review article synthesizes the authors' several decades of multidisciplinary natural and social science and applied marine resource management experience in the Asia-Pacific region to examine the strengthening of coastal and marine resource management and conservation using alliances between local communities and external institutions. The objective is to assist the design of resource management and conservation programs that enhance the capacity of coastal communities in Oceania to confront both diminishing marine resources and the effects of climate change by providing guidelines for protecting marine biodiversity and vulnerable ecosystem functions. This article describes a management framework that hybridizes local beliefs and institutions expressed in customary management (CM) with such modern management concepts as marine protected areas (MPAs) and ecosystem-based management (EBM). Hybrid management accommodates the social, political, economic, and cultural contexts of Oceanic communities and, compared with recent or conventional management approaches, can therefore better address fundamental local concerns such as coastal degradation, climate change, sea level rise, weak governance, corruption, limited resources and staff to manage and monitor marine resources, and increasing poverty. Research on the hybridization of management systems demonstrates opportunities to establish context-appropriate EBM and/or other managerial arrangements that include terrestrial and adjacent coastal-marine ecosystems. Formal and informal CM systems are widespread in Oceania and in some parts of Southeast Asia, and if appropriate strategies are employed rapid progress toward hybrid CM-EBM could be enabled.
- Full Text:
- Date Issued: 2013
- Authors: Aswani, Shankar , Ruddle, Kenneth
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/422721 , vital:71972 , xlink:href="https://doi.org/10.2984/67.3.11"
- Description: This review article synthesizes the authors' several decades of multidisciplinary natural and social science and applied marine resource management experience in the Asia-Pacific region to examine the strengthening of coastal and marine resource management and conservation using alliances between local communities and external institutions. The objective is to assist the design of resource management and conservation programs that enhance the capacity of coastal communities in Oceania to confront both diminishing marine resources and the effects of climate change by providing guidelines for protecting marine biodiversity and vulnerable ecosystem functions. This article describes a management framework that hybridizes local beliefs and institutions expressed in customary management (CM) with such modern management concepts as marine protected areas (MPAs) and ecosystem-based management (EBM). Hybrid management accommodates the social, political, economic, and cultural contexts of Oceanic communities and, compared with recent or conventional management approaches, can therefore better address fundamental local concerns such as coastal degradation, climate change, sea level rise, weak governance, corruption, limited resources and staff to manage and monitor marine resources, and increasing poverty. Research on the hybridization of management systems demonstrates opportunities to establish context-appropriate EBM and/or other managerial arrangements that include terrestrial and adjacent coastal-marine ecosystems. Formal and informal CM systems are widespread in Oceania and in some parts of Southeast Asia, and if appropriate strategies are employed rapid progress toward hybrid CM-EBM could be enabled.
- Full Text:
- Date Issued: 2013
Determinants of life satisfaction among race groups in South Africa
- Ebrahim, Amina, Botha, Ferdi, Snowball, Jeanette D
- Authors: Ebrahim, Amina , Botha, Ferdi , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69311 , vital:29497 , https://doi.org/10.1080/0376835x.2013.797227
- Description: Economic indicators, like gross domestic product per capita, are commonly used as indicators of welfare. However, they have a very limited and narrow scope, excluding many potentially important welfare determinants, such as health, relative income and religion – not surprising since they were not designed to fill this role. As a result, there is growing acceptance, and use of, subjective measures of well-being (called ‘happiness’ or ‘life satisfaction’, often used interchangeably) both worldwide and in South Africa. Happiness economics does not propose to replace income-based measures of well-being, but rather attempts to complement them with broader measures, which can be important in making policy decisions that optimise societal welfare. This paper tests for differences in subjective well-being between race groups in South Africa, and investigates the determinants of self-rated life satisfaction for each group. Using the 2008 National Income Dynamics Study data, descriptive methods (analysis of variance) and an ordered probit model are applied. Results indicate that reported life satisfaction differs substantially among race groups, with black South Africans being the least satisfied group despite changes since the advent of democracy in 1994. Higher levels of educational attainment increased satisfaction for the whole sample, and women (particularly black women) are generally less satisfied than men. As found in many other studies, unemployed people have lower levels of life satisfaction than the employed, even when controlling for income and relative income. The determinants of life satisfaction are also different for each race group: white South Africans attach greater importance to physical health, whereas employment status and absolute income matter greatly for black people. For coloured people and black people, positional status (as measured by relative income) is an important determinant of well-being, with religious involvement contributing significantly to the well-being of Indian people.
- Full Text: false
- Date Issued: 2013
- Authors: Ebrahim, Amina , Botha, Ferdi , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69311 , vital:29497 , https://doi.org/10.1080/0376835x.2013.797227
- Description: Economic indicators, like gross domestic product per capita, are commonly used as indicators of welfare. However, they have a very limited and narrow scope, excluding many potentially important welfare determinants, such as health, relative income and religion – not surprising since they were not designed to fill this role. As a result, there is growing acceptance, and use of, subjective measures of well-being (called ‘happiness’ or ‘life satisfaction’, often used interchangeably) both worldwide and in South Africa. Happiness economics does not propose to replace income-based measures of well-being, but rather attempts to complement them with broader measures, which can be important in making policy decisions that optimise societal welfare. This paper tests for differences in subjective well-being between race groups in South Africa, and investigates the determinants of self-rated life satisfaction for each group. Using the 2008 National Income Dynamics Study data, descriptive methods (analysis of variance) and an ordered probit model are applied. Results indicate that reported life satisfaction differs substantially among race groups, with black South Africans being the least satisfied group despite changes since the advent of democracy in 1994. Higher levels of educational attainment increased satisfaction for the whole sample, and women (particularly black women) are generally less satisfied than men. As found in many other studies, unemployed people have lower levels of life satisfaction than the employed, even when controlling for income and relative income. The determinants of life satisfaction are also different for each race group: white South Africans attach greater importance to physical health, whereas employment status and absolute income matter greatly for black people. For coloured people and black people, positional status (as measured by relative income) is an important determinant of well-being, with religious involvement contributing significantly to the well-being of Indian people.
- Full Text: false
- Date Issued: 2013
Determinants of student satisfaction with campus residence life at a South African University
- Botha, Ferdi, Snowball, Jeanette D, De Klerk, Vivian A, Radloff, Sarah E
- Authors: Botha, Ferdi , Snowball, Jeanette D , De Klerk, Vivian A , Radloff, Sarah E
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68543 , vital:29281 , https://econrsa.org/publications/working-papers/determinants-student-satisfaction-campus-residence-life-south-african
- Description: Publisher version , Although there are a number of studies on the determinants of general quality of life among university students, these occur mainly in developed countries and do not focus specifically on campus-based residence life. It has long been accepted that factors outside the classroom (“the other curriculum”) can contribute to academic success, as well as the achievement of other important outcomes such as the appreciation of human diversity. Striving towards equality of residence life satisfaction across different racial and gender groups, for example, is thus important for academic outcomes and for the development of well-functioning citizens. This study is based on the 2011 Quality of Residence Life (QoRL) Survey, conducted at a South African university, comprising roughly 2 000 respondents. Based on descriptive analyses and ordered probit regressions, the study investigates the association between satisfaction with QoRL and (i) residence milieu and characteristics, (ii) direct and indirect discrimination, (iii) perceptions of drug and alcohol issues in residence, (iv) safety, and (v) individual student characteristics. One of the main findings is that there are no significant differences in satisfaction with QoRL across racial and gender groups; a finding that suggests significant progress in university transformation and equity goals. The general atmosphere and characteristics of residences are also important predictors of QoRL satisfaction. , Economic Research Southern Africa (ERSA) is a research programme funded by the National Treasury of South Africa.
- Full Text:
- Date Issued: 2013
- Authors: Botha, Ferdi , Snowball, Jeanette D , De Klerk, Vivian A , Radloff, Sarah E
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68543 , vital:29281 , https://econrsa.org/publications/working-papers/determinants-student-satisfaction-campus-residence-life-south-african
- Description: Publisher version , Although there are a number of studies on the determinants of general quality of life among university students, these occur mainly in developed countries and do not focus specifically on campus-based residence life. It has long been accepted that factors outside the classroom (“the other curriculum”) can contribute to academic success, as well as the achievement of other important outcomes such as the appreciation of human diversity. Striving towards equality of residence life satisfaction across different racial and gender groups, for example, is thus important for academic outcomes and for the development of well-functioning citizens. This study is based on the 2011 Quality of Residence Life (QoRL) Survey, conducted at a South African university, comprising roughly 2 000 respondents. Based on descriptive analyses and ordered probit regressions, the study investigates the association between satisfaction with QoRL and (i) residence milieu and characteristics, (ii) direct and indirect discrimination, (iii) perceptions of drug and alcohol issues in residence, (iv) safety, and (v) individual student characteristics. One of the main findings is that there are no significant differences in satisfaction with QoRL across racial and gender groups; a finding that suggests significant progress in university transformation and equity goals. The general atmosphere and characteristics of residences are also important predictors of QoRL satisfaction. , Economic Research Southern Africa (ERSA) is a research programme funded by the National Treasury of South Africa.
- Full Text:
- Date Issued: 2013
Developing a virtualised testbed environment in preparation for testing of network based attacks
- Van Heerden, Renier, Pieterse, Heloise, Burke, Ivan, Irwin, Barry V W
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
- Authors: Van Heerden, Renier , Pieterse, Heloise , Burke, Ivan , Irwin, Barry V W
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429648 , vital:72629 , 10.1109/ICASTech.2013.6707509
- Description: Computer network attacks are difficult to simulate due to the damage they may cause to live networks and the complexity required simulating a useful network. We constructed a virtualised network within a vSphereESXi environment which is able to simulate: thirty workstations, ten servers, three distinct network segments and the accompanying network traffic. The VSphere environment provided added benefits, such as the ability to pause, restart and snapshot virtual computers. These abilities enabled the authors to reset the simulation environment before each test and mitigated against the damage that an attack potentially inflicts on the test network. Without simulated network traffic, the virtualised network was too sterile. This resulted in any network event being a simple task to detect, making network traffic simulation a requirement for an event detection test bed. Five main kinds of traffic were simulated: Web browsing, File transfer, e-mail, version control and Intranet File traffic. The simulated traffic volumes were pseudo randomised to represent differing temporal patterns. By building a virtualised network with simulated traffic we were able to test IDS' and other network attack detection sensors in a much more realistic environment before moving it to a live network. The goal of this paper is to present a virtualised testbedenvironmentin which network attacks can safely be tested.
- Full Text:
- Date Issued: 2013
Digital multimedia network with latency control
- Gurdan, Robby, Foss, Richard
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427043 , vital:72410 , https://patentimages.storage.googleapis.com/59/e3/43/6b49b528623ea3/US8477812.pdf
- Description: The present invention relates to a digital multimedia network 1 with latency control comprising apparatuses for processing of data streams, wherein a borderline input apparatus providing a data stream generates a latency time stamp (LTS) which contains an absolute time indicating a creation time of said data stream and an accumulated delay time which is updated by each apparatus processing said data stream, wherein said latency time stamp (LTS) of said data stream is evaluated by a borderline output apparatus of said network which synchronizes said data stream.
- Full Text:
- Date Issued: 2013
- Authors: Gurdan, Robby , Foss, Richard
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427043 , vital:72410 , https://patentimages.storage.googleapis.com/59/e3/43/6b49b528623ea3/US8477812.pdf
- Description: The present invention relates to a digital multimedia network 1 with latency control comprising apparatuses for processing of data streams, wherein a borderline input apparatus providing a data stream generates a latency time stamp (LTS) which contains an absolute time indicating a creation time of said data stream and an accumulated delay time which is updated by each apparatus processing said data stream, wherein said latency time stamp (LTS) of said data stream is evaluated by a borderline output apparatus of said network which synchronizes said data stream.
- Full Text:
- Date Issued: 2013
Does national sporting performance affect stock market returns in South Africa?
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
- Authors: Botha, Ferdi , De Beer, Carl
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396023 , vital:69144 , xlink:href="https://hdl.handle.net/10520/EJC135922"
- Description: This study explores whether South African national sporting performance can influence investors in such a way that it has the ability to impact on market returns. Using standard event study methodology, this study determines the constant mean return using the daily All-Share price index on the JSE for the period of 1 January 1990 to 31 December 2010. This study focuses on three of South Africa's most popular sports, namely soccer, cricket and rugby, and examines if these three sports have the ability to influence market returns. Although there is some evidence of a relationship between stock returns and sporting performance in the descriptive analysis, the regression results indicate that sporting performance in South Africa does not significantly explain abnormal market returns on the JSE. The study provides a number of possible reasons for this finding and concludes by suggesting areas for future research.
- Full Text:
- Date Issued: 2013
Dynamic geometry software as a dynamic tool for spatial exploration:
- Holzl, Reinhard, Schäfer, Marc
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
- Date Issued: 2013
- Authors: Holzl, Reinhard , Schäfer, Marc
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140871 , vital:37925 , https://hdl.handle.net/10520/EJC146065
- Description: Dynamic Geometry Software (DGS) such as GeoGebra, Geometer's Sketchpad and Cabri Geometry offer a wealth of opportunities for an exploratory style of teaching and learning Mathematics, particularly in the exploration of space and shape. The new Curriculum and Assessment Policy Statement (CAPS) foregrounds the use of spatial skills and properties of shapes and objects "to identify, pose and solve problems creatively and critically" (South Africa. DBE, 2011, p. 9). Although the South African Mathematics curriculum no longer places importance on traditional Euclidean construction by means of straightedge and compass, DGS can nonetheless be used to engage with fundamental ideas relating to geometric shapes, symmetry and transformations. This was the impetus behind encouraging the use of GeoGebra in four township schools in the Grahamstown Education District whose Mathematics teachers participate in an ongoing in-service research and development programme hosted by Rhodes University.
- Full Text:
- Date Issued: 2013
E-skills training on communal, fixed infrastructure as an activator of personal use of mobile internet
- Gumbo, Sibukelo, Terzoli, Alfredo
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
- Authors: Gumbo, Sibukelo , Terzoli, Alfredo
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430716 , vital:72710 , https://ieeexplore.ieee.org/abstract/document/6701781
- Description: In the second semester of 2012, training in computer literacy was of-fered in the Dwesa area, in deep rural South Africa, within the footprint of the Siyakhula Living Lab. Training of this nature is essential to make ICT access meaningful in such areas, and avoid wasteful `box drop-ping', unfortunately not uncommon. The training was done using com-munal fixed infrastructure located in schools but, interestingly, activated or deepened the use of mobile intemet among the people that attended the training. This paper contributes on the ongoing debate on whether mobile devices are the one and only solution to ICT access in rural (and peri-urban) poor settings in Africa.
- Full Text:
- Date Issued: 2013
Ecological niche modeling of the invasive potential of Nile tilapia Oreochromis niloticus in African river systems: concerns and implications for the conservation of indigenous congenerics
- Zengeya, Tsungai A, Robertson, Mark P, Booth, Anthony J, Chimimba, Christian T
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
- Date Issued: 2013
- Authors: Zengeya, Tsungai A , Robertson, Mark P , Booth, Anthony J , Chimimba, Christian T
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124341 , vital:35596 , https://doi.10.1007/s10530-012-0386-7
- Description: This study applied ecological niche models to determine the potential invasive range of Nile tilapia, Oreochromis niloticus, with a particular focus on river systems in southern Africa where it is now established and spreading. Computational tools such as niche models are useful in predicting the potential range of invasive species, but there are limitations to their application. In particular, models trained on native records may fail to predict the full extent of an invasion. This failure is often attributed to changes in either the niche of the invading species or the variables used to develop the models. In this study, we therefore evaluated the differences in the predictive power of models trained with different environmental variables, the effect of species range (native vs. introduced) on model performance and assessed whether or not there is evidence suggestive of a niche shift in Nile tilapia following its introduction. Niche models were constructed using Maxent and the degree of niche similarity was assessed using Schoener‘s index. Null models were used to test for significance. Model performance and niche conservatism varied significantly with variable selection and species range. This indicates that the environmental conditions available to Nile tilapia in its native and introduced ranges are not congruent. Nile tilapia exhibited broad invasive potential over most of southern Africa that overlaps the natural range of endemic congenerics. Of particular concern are areas which are free of exotic species but are now vulnerable due to the promotion of fish introductions mainly for aquaculture and sport fishing.
- Full Text:
- Date Issued: 2013
Editorial. Methodology, Context and Quality
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387220 , vital:68216 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122254"
- Description: This edition of the Southern African Journal of Environmental Education (SAJEE) is a ‘double volume’ and contains papers submitted in 2012 and 2013. The production of a double volume has been necessitated by administrative problems experienced by the journal production team in 2012, which affected the successful publication of a 2012 edition. However, the Council of the Environmental Education Association of Southern Africa (EEASA) agreed to respond by producing a double-volume edition for 2012/2013. Journal readers are reminded that the production of this journal is voluntary and depends heavily on voluntary administration and other systems. The patience of authors and readers in the 2012/2013 years of production is much appreciated.
- Full Text:
- Date Issued: 2013
Editorial:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158840 , vital:40233 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Date Issued: 2013
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158840 , vital:40233 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Date Issued: 2013
Editorial:
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158851 , vital:40234 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Date Issued: 2013
- Authors: Garman, Anthea
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158851 , vital:40234 , https://hdl.handle.net/10520/EJC141608
- Description: If you've been a Rhodes Journalism Review reader for a while, you'll be surprised by the smaller magazine you are holding in your hands right now. RJR started off life as an A4 but has been big since no 9, December 1994, and the size I inherited when I started as editor in 1997. It's a format I've always loved; it stands (er, stood) out among the wash of pamphlets at international conferences, it gave designers and photographers a fantastic sweep of canvas, and it was distinctive in the world of magazines, a true original.
- Full Text:
- Date Issued: 2013
Effect of the relative humidity on the fibre morphology of polyamide 4.6 and polyamide 6.9 nanofibres
- De Schoenmaker, Bert, Van de Schueren, Lien, Zugle, Ruphino, Goethals, Annelies, Westbroek, Philippe, Kiekens, Paul, Nyokong, Tebello, De Clerck, Karen
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
- Authors: De Schoenmaker, Bert , Van de Schueren, Lien , Zugle, Ruphino , Goethals, Annelies , Westbroek, Philippe , Kiekens, Paul , Nyokong, Tebello , De Clerck, Karen
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/242131 , vital:51004 , xlink:href="https://doi.org/10.1007/s10853-012-6934-9"
- Description: To obtain uniform and reproducible nanofibres, it is important to understand the effect of the different electrospinning parameters on the nanofibre morphology. Even though a lot of literature is available on the electrospinning of nanofibres, only minor research has been performed on the effect of the relative humidity (RH). This paper investigates the influence of this parameter on the electrospinning process and fibre morphology of the hydrophilic polyamide 4.6 and the less hydrophilic polyamide 6.9. First, the electrospinning process and deposition area of the nanofibres is examined at 10, 50 and 70 % RH. Subsequently, the effect of the polyamide concentration and solvent ratio on the fibre morphology is investigated using scanning electron microscopy and differential scanning calorimetry. It was found that the nanofibre diameter decreased with increasing RH. This resulted in less stable crystals for polyamide 4.6 while electrospinning of polyamide 6.9 at higher RH led to slightly more stable crystals. In conclusion, the water affinity of a polymer is an important factor in predicting the nanofibre morphology at different humidities.
- Full Text:
- Date Issued: 2013
Effects of gold nanoparticle shape on the aggregation and fluorescence behaviour of water soluble zinc phthalocyanines
- D'Souza, Sarah, Moeno, Sharon, Antunes, Edith M, Nyokong, Tebello
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
- Date Issued: 2013
- Authors: D'Souza, Sarah , Moeno, Sharon , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/232500 , vital:49997 , xlink:href="https://doi.org/10.1039/C3NJ00146F"
- Description: The absorption and fluorescence response as well as the fluorescence quantum yields and lifetimes of sulfonated phthalocyanines and alkyl carboxylic acid substituted zinc phthalocyanines in the presence of differently shaped water soluble gold nanoparticles were studied. The respective phthalocyanines are known to be highly aggregated in water, which is reported to markedly reduce the excited state lifetimes. This paper shows that in the presence of star shaped gold nanoparticles, the degree of phthalocyanine aggregation in water is greatly reduced, but the aggregation status of the phthalocyanines does not change for spherical Au nanoparticles. Since gold nanoparticles have already proven to be useful in numerous nanomedicinal and nanomedical applications, the disaggregation of phthalocyanines is an added advantage.
- Full Text:
- Date Issued: 2013
Electrochemical impedimetric immunosensor for the detection of measles-specific IgG antibodies after measles infections
- Mashazi, Philani N, Tetyana, Phumlani, Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
- Authors: Mashazi, Philani N , Tetyana, Phumlani , Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241677 , vital:50960 , xlink:href="https://doi.org/10.1016/j.bios.2013.04.028"
- Description: The detection of measles-specific primary antibodies (IgG) using electrochemical impedimetric immunosensors is reported. The optimum conditions for electrode saturation were reached after 40 min for 1 μg ml−1 antibody concentrations. Surface roughness using AFM increased with each immobilization or antigen-antibody reaction step clearly confirming the surface modification and recognition between antigen and antibody. The human serum (HS) and new-born calf serum (NCS) spiked with antigen-specific antibody were studied to mimic the real sample analysis. The HS and NCS sera containing antibodies due to measles exhibited correlation between the increasing antibody serum concentrations and the charge-transfer resistance (electrochemically measured). This work clearly showed the potential use of impedance as the preferred electrochemical method for detecting measles-antibodies in label-free manner.
- Full Text:
- Date Issued: 2013
Electrospun fibers functionalized with phthalocyanine-gold nanoparticle conjugates for photocatalytic applications
- Tombe, Sekai, Antunes, Edith M, Nyokong, Tebello
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
- Full Text:
- Date Issued: 2013
- Authors: Tombe, Sekai , Antunes, Edith M , Nyokong, Tebello
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193769 , vital:45394 , xlink:href="https://doi.org/10.1016/j.molcata.2013.01.033"
- Description: The heterogeneous photocatalytic activity of Zn(II) phthalocyanine-gold nanoparticle conjugates immobilized on electrospun polystyrene fibers was investigated using 4-chlorophenol and Orange G as model pollutants. The phthalocyanine-gold nanoparticle conjugates were synthesized via a ligand exchange reaction and characterized using spectroscopic and microscopic techniques. The interaction between the gold nanoparticles and phthalocyanines did not restrict the formation of excited singlet states, triplet states and hence the formation of singlet oxygen required for photocatalysis. The conjugates showed significantly higher singlet oxygen quantum yields and enhanced photocatalytic activity compared to the phthalocyanines. It was concluded that hybrid electrospun fibers provide great potential as active photocatalysts for oxidizing organic pollutants using singlet oxygen as an oxidant.
- Full Text:
- Date Issued: 2013
Engineering Education Research for educational change: the possibilities of critical realism for conceptualising causal mechanicsms in education
- Case, Jennifer, Blackie, Margaret A
- Authors: Case, Jennifer , Blackie, Margaret A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
- Date Issued: 2013
- Authors: Case, Jennifer , Blackie, Margaret A
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426637 , vital:72374 , xlink:href="https://doi.org/10.1016/j.biocontrol.2013.07.023"
- Description: Engineering Education Research (EER) grew in prominence from the late 1990s as purposes for this field were espoused in relation to the necessity of change for engineering education in the newly globalising world. Arguments centred on overall challenges with recruitment to engineering, specifically in relation to historically underrepresented populations, as well as with the forms of education (both in terms of quality of teaching and relevance of curricula) offered to students, and the needs of employers as reflected in newly-emerged global accreditation systems. In a field that is at least partly directed towards educational change, there is a need to understand how change typically happens in education systems. This article first draws on findings from the sociology of education to show that causality in relation to educational change is complex. It then turns to the philosophy of critical realism for a way of thinking about change that can inform EER, and concludes by outlining how this might change the research questions that drive the field, and how these might be approached.
- Full Text:
- Date Issued: 2013
Epidemic transmission of intestinal schistosomiasis in the seasonal part of the Okavango Delta, Botswana:
- Appleton, C C, Ellery, William F N, Byskov, Jens, Mogkweetsinyana, S S
- Authors: Appleton, C C , Ellery, William F N , Byskov, Jens , Mogkweetsinyana, S S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144364 , vital:38339 , DOI: 10.1179/136485908X311867
- Description: A well documented epidemic of human intestinal schistosomiasis caused by Schistosoma mansoni occurred at Maun in the seasonal part of the Okavango Delta, Botswana, building from very few cases in the 1950s and early 1960s to a peak prevalence of greater than80% in the 1980s. A retrospective analysis was performed on all available records of the prevalence of S. mansoni in the Maun area and the corresponding flow records of the Thamalakane River. These revealed a statistically significant correlation between prevalence and flow, but only when a lag period was introduced. The correlation was greatest with a lag period of 5–6 years between the rise and fall of discharge and the rise and fall of transmission. Since the hydrological events in the delta follow a cyclical pattern, another epidemic around 2020 appears likely.
- Full Text:
- Date Issued: 2013
- Authors: Appleton, C C , Ellery, William F N , Byskov, Jens , Mogkweetsinyana, S S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144364 , vital:38339 , DOI: 10.1179/136485908X311867
- Description: A well documented epidemic of human intestinal schistosomiasis caused by Schistosoma mansoni occurred at Maun in the seasonal part of the Okavango Delta, Botswana, building from very few cases in the 1950s and early 1960s to a peak prevalence of greater than80% in the 1980s. A retrospective analysis was performed on all available records of the prevalence of S. mansoni in the Maun area and the corresponding flow records of the Thamalakane River. These revealed a statistically significant correlation between prevalence and flow, but only when a lag period was introduced. The correlation was greatest with a lag period of 5–6 years between the rise and fall of discharge and the rise and fall of transmission. Since the hydrological events in the delta follow a cyclical pattern, another epidemic around 2020 appears likely.
- Full Text:
- Date Issued: 2013
Exploring a systems approach to mainstreaming sustainability in universities: A case study of Rhodes University in South Africa
- Togo, Muchaiteyi, Lotz-Sisitka, Heila
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013
- Authors: Togo, Muchaiteyi , Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182857 , vital:43886 , xlink:href="https://doi.org/10.1080/13504622.2012.749974"
- Description: This paper explores the use of systems theory to inform the mainstreaming of sustainability in a university’s functions as it responds to sustainable development challenges in its local context. Offering a case study of Rhodes University, the paper shows how the use of systems models and concepts, underpinned by a critical realist ontology and an understanding of morphogenetic change processes, have the potential to enable universities to mobilise their operations to respond to local sustainability challenges. In this instance, the success of such an approach is shown to depend on commitments from the university community and the availability of enabling inputs, such as financial and human resources. The paper concludes with reflections and recommendations to inform further development of a newly emerging systems approach in sustainability mainstreaming at Rhodes University, and other institutions pursuing similar approaches and goals.
- Full Text:
- Date Issued: 2013