Data on microhardness and structural analysis of friction stir spot welded lap joints of AA5083-H116
- Esther T. Akinlabi, Ayuba S. Osinubi b, Nkosinathi Madushele b, Stephen A. Akinlabi c, Omolayo M. Ikumapayi d,∗
- Authors: Esther T. Akinlabi , Ayuba S. Osinubi b , Nkosinathi Madushele b , Stephen A. Akinlabi c , Omolayo M. Ikumapayi d,∗
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3260 , vital:43286 , https://www.sciencedirect.com/science/article/pii/S2352340920314669
- Description: Friction stir spot welding (FSSW) was established to compete reasonably with the reverting, bolting, adhesive bonding as well as resistance spot welding (RSW) which have been used in the past for lap joining in automobile, aerospace, marine, railways, defence and shipbuilding industries. The use of these ancient and conventional joining techniques had led to increasing material cost, installation labour, and additional weight in the aircraft, shipbuilding, and other areas of applications. All these are disadvantages that can be overcome using FSSW. This research work carried out friction stir spot welding on 5058-H116 aluminium alloy by employing rotational speed in the step of 300 rpm ranges from 600 rpm to 1200 rpm with a no travel speed. It was noted that the dwell times were in the step of 5 s varying from 5 s to 15 s while the tool plunge rate was maintained at 30 mm/min. In this dataset, a cylindrical tapered rotating H13 Hot-working steel tool was used with a probe length of 5 mm and probe diameter of 6 mm, it has a shoulder diameter of 18 mm. The tool penetration depth (plunge) was maintained at 0.2 mm and the tool tilt angle at 2°. Structural integrity was car-ried out using Rigaku ultima IV multifunctional X-ray diffractometer (XRD) with a scan voltage of 40 kV and scan current of 30 mA. This was used to determine crystallite sizes, peak intensity, d-spacing, full width at half maximum intensity (FWHM) of the diffraction peak. TH713 digital microhardness equipment with diamond indenter was used for microhardness data acquisition following ASTM E92–82 standard test. The average Vickers hardness data values at different zones of the spot-welds were captured and presented.
- Full Text:
- Date Issued: 2020
Data on microhardness and structural analysis of friction stir spot welded lap joints of AA5083-H116
- Authors: Esther T. Akinlabi , Ayuba S. Osinubi b , Nkosinathi Madushele b , Stephen A. Akinlabi c , Omolayo M. Ikumapayi d,∗
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3260 , vital:43286 , https://www.sciencedirect.com/science/article/pii/S2352340920314669
- Description: Friction stir spot welding (FSSW) was established to compete reasonably with the reverting, bolting, adhesive bonding as well as resistance spot welding (RSW) which have been used in the past for lap joining in automobile, aerospace, marine, railways, defence and shipbuilding industries. The use of these ancient and conventional joining techniques had led to increasing material cost, installation labour, and additional weight in the aircraft, shipbuilding, and other areas of applications. All these are disadvantages that can be overcome using FSSW. This research work carried out friction stir spot welding on 5058-H116 aluminium alloy by employing rotational speed in the step of 300 rpm ranges from 600 rpm to 1200 rpm with a no travel speed. It was noted that the dwell times were in the step of 5 s varying from 5 s to 15 s while the tool plunge rate was maintained at 30 mm/min. In this dataset, a cylindrical tapered rotating H13 Hot-working steel tool was used with a probe length of 5 mm and probe diameter of 6 mm, it has a shoulder diameter of 18 mm. The tool penetration depth (plunge) was maintained at 0.2 mm and the tool tilt angle at 2°. Structural integrity was car-ried out using Rigaku ultima IV multifunctional X-ray diffractometer (XRD) with a scan voltage of 40 kV and scan current of 30 mA. This was used to determine crystallite sizes, peak intensity, d-spacing, full width at half maximum intensity (FWHM) of the diffraction peak. TH713 digital microhardness equipment with diamond indenter was used for microhardness data acquisition following ASTM E92–82 standard test. The average Vickers hardness data values at different zones of the spot-welds were captured and presented.
- Full Text:
- Date Issued: 2020
Decolonisation as a spatial question: the student accommodation crisis and Higher Education transformation
- Mzileni, Pedro, Mkhize, Nomalanga
- Authors: Mzileni, Pedro , Mkhize, Nomalanga
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156378 , vital:39984 , DOI: 10.1080/21528586.2020.1733649
- Description: Debates on epistemological decolonisation have focused on curriculum issues. There has not been sufficient analysis of how questions of decolonisation are shaped by other factors, such as the very spatial location of universities. This article argues that the colonial nature of the university in South Africa is directly linked spatially to the historic land question of dispossession in South Africa. Historically, South African universities came to be fixed as physical and cultural elements of towns and cities based on the broader trajectory of settler-colonialism and apartheid urban development, segregation and the Group Areas logic of the apartheid state.
- Full Text:
- Date Issued: 2020
- Authors: Mzileni, Pedro , Mkhize, Nomalanga
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156378 , vital:39984 , DOI: 10.1080/21528586.2020.1733649
- Description: Debates on epistemological decolonisation have focused on curriculum issues. There has not been sufficient analysis of how questions of decolonisation are shaped by other factors, such as the very spatial location of universities. This article argues that the colonial nature of the university in South Africa is directly linked spatially to the historic land question of dispossession in South Africa. Historically, South African universities came to be fixed as physical and cultural elements of towns and cities based on the broader trajectory of settler-colonialism and apartheid urban development, segregation and the Group Areas logic of the apartheid state.
- Full Text:
- Date Issued: 2020
Detecting plant species in the field with deep learning and drone technology:
- James, Katherine M F, Bradshaw, Karen L
- Authors: James, Katherine M F , Bradshaw, Karen L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160445 , vital:40446 , https://0-doi.org.wam.seals.ac.za/10.1111/2041-210X.13473
- Description: Aerial drones are providing a new source of high‐resolution imagery for mapping of plant species of interest, amongst other applications. On‐board detection algorithms could open the door to allow for applications in which drones can intelligently interact with their environment. However, the majority of plant detection studies have focused on detection in post‐flight processed orthomosaics. Greater research into developing detection algorithms robust to real‐world variations in environmental conditions is necessary, such that they are suitable for deployment in the field under variable conditions. We outline the steps necessary to develop such a system, show by example how real‐world considerations can be addressed during model training and briefly illustrate the performance of our best performing model in the field when integrated with an aerial drone.
- Full Text:
- Date Issued: 2020
- Authors: James, Katherine M F , Bradshaw, Karen L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160445 , vital:40446 , https://0-doi.org.wam.seals.ac.za/10.1111/2041-210X.13473
- Description: Aerial drones are providing a new source of high‐resolution imagery for mapping of plant species of interest, amongst other applications. On‐board detection algorithms could open the door to allow for applications in which drones can intelligently interact with their environment. However, the majority of plant detection studies have focused on detection in post‐flight processed orthomosaics. Greater research into developing detection algorithms robust to real‐world variations in environmental conditions is necessary, such that they are suitable for deployment in the field under variable conditions. We outline the steps necessary to develop such a system, show by example how real‐world considerations can be addressed during model training and briefly illustrate the performance of our best performing model in the field when integrated with an aerial drone.
- Full Text:
- Date Issued: 2020
Detection of the in vitro modulation of Plasmodium falciparum Arf1 by Sec7 and ArfGAP domains using a colorimetric plate-based assay:
- Swart, Tarryn, Khan, Farrah D, Ntlantsana, Apelele, Laming, Dustin, Veale, Clinton G L, Przyborski, Jude M, Edkins, Adrienne L, Hoppe, Heinrich C
- Authors: Swart, Tarryn , Khan, Farrah D , Ntlantsana, Apelele , Laming, Dustin , Veale, Clinton G L , Przyborski, Jude M , Edkins, Adrienne L , Hoppe, Heinrich C
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165418 , vital:41242 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-020-61101-3
- Description: The regulation of human Arf1 GTPase activity by ArfGEFs that stimulate GDP/GTP exchange and ArfGAPs that mediate GTP hydrolysis has attracted attention for the discovery of Arf1 inhibitors as potential anti-cancer agents. The malaria parasite Plasmodium falciparum encodes a Sec7 domain-containing protein - presumably an ArfGEF - and two putative ArfGAPs, as well as an Arf1 homologue (PfArf1) that is essential for blood-stage parasite viability. However, ArfGEF and ArfGAP-mediated activation/deactivation of PfArf1 has not been demonstrated.
- Full Text:
- Date Issued: 2020
- Authors: Swart, Tarryn , Khan, Farrah D , Ntlantsana, Apelele , Laming, Dustin , Veale, Clinton G L , Przyborski, Jude M , Edkins, Adrienne L , Hoppe, Heinrich C
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165418 , vital:41242 , https://0-doi.org.wam.seals.ac.za/10.1038/s41598-020-61101-3
- Description: The regulation of human Arf1 GTPase activity by ArfGEFs that stimulate GDP/GTP exchange and ArfGAPs that mediate GTP hydrolysis has attracted attention for the discovery of Arf1 inhibitors as potential anti-cancer agents. The malaria parasite Plasmodium falciparum encodes a Sec7 domain-containing protein - presumably an ArfGEF - and two putative ArfGAPs, as well as an Arf1 homologue (PfArf1) that is essential for blood-stage parasite viability. However, ArfGEF and ArfGAP-mediated activation/deactivation of PfArf1 has not been demonstrated.
- Full Text:
- Date Issued: 2020
Enhanced photodynamic antimicrobial activity of surface modified SiNPs doped with zinc (II) phthalocyanines: the effect of antimicrobial ampicillin and extra charges from a sultone
- Magadla, Aviwe, Nyokong, Tebello
- Authors: Magadla, Aviwe , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160511 , vital:40452 , https://doi.org/10.1016/j.pdpdt.2020.101996
- Description: 1-(2-Methoxyethyl)piperidine sustituted Zn phthalocyanine complex (2) is synthesised and quartenised (3). These complexes are loaded into silica nanoparticles (SiNPs) that are futher surface modified with ampicillin and 1.3-propanesultone. The photophysical and photochemical properties of the complexes and their doped conjugates were investigated in dimethylsulfoxide. The cationic complex (3) is used for photodynamic antimicrobial activity. Log reduction values of above 9 are obtained towards the photoiactivation of Staphyloccocus aureus.
- Full Text:
- Date Issued: 2020
- Authors: Magadla, Aviwe , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/160511 , vital:40452 , https://doi.org/10.1016/j.pdpdt.2020.101996
- Description: 1-(2-Methoxyethyl)piperidine sustituted Zn phthalocyanine complex (2) is synthesised and quartenised (3). These complexes are loaded into silica nanoparticles (SiNPs) that are futher surface modified with ampicillin and 1.3-propanesultone. The photophysical and photochemical properties of the complexes and their doped conjugates were investigated in dimethylsulfoxide. The cationic complex (3) is used for photodynamic antimicrobial activity. Log reduction values of above 9 are obtained towards the photoiactivation of Staphyloccocus aureus.
- Full Text:
- Date Issued: 2020
Implementing prolonged exposure therapy for PTSD in a context of ongoing adversity: a clinical case study
- Booysen, Duane D, Kagee, Ashraf
- Authors: Booysen, Duane D , Kagee, Ashraf
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149275 , vital:38821 , https://0-doi.org.wam.seals.ac.za/10.1177/1534650120925918
- Description: Obstacles regarding the implementation of empirically supported treatments (ESTs) for mental disorders such as post-traumatic stress disorder (PTSD) still require further investigation. One notable obstacle is whether persons in low- and middle-income countries (LMICs) residing in a context of ongoing adversity would benefit from an EST for PTSD. We reflect on the utility of a brief prolonged exposure intervention at a primary care community-counseling center in South Africa. “Sam,” a 45-year-old, female was assessed at baseline, during treatment, postassessment, and at 3-month follow-up. At the beginning of treatment, Sam had a positive diagnosis for PTSD (PSSI-5 = 55, and cutoff is 23) and at the end of treatment (PSSI-5 = 17), and 3-month follow-up (PSSI-5 = 21), she had a negative diagnosis for PTSD. We reflect on the mediating effects that contextual factors such as gang violence had on the treatment process and the feasibility of implementing ESTs for PTSD in LMICs under conditions of ongoing adversity.
- Full Text:
- Date Issued: 2020
- Authors: Booysen, Duane D , Kagee, Ashraf
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149275 , vital:38821 , https://0-doi.org.wam.seals.ac.za/10.1177/1534650120925918
- Description: Obstacles regarding the implementation of empirically supported treatments (ESTs) for mental disorders such as post-traumatic stress disorder (PTSD) still require further investigation. One notable obstacle is whether persons in low- and middle-income countries (LMICs) residing in a context of ongoing adversity would benefit from an EST for PTSD. We reflect on the utility of a brief prolonged exposure intervention at a primary care community-counseling center in South Africa. “Sam,” a 45-year-old, female was assessed at baseline, during treatment, postassessment, and at 3-month follow-up. At the beginning of treatment, Sam had a positive diagnosis for PTSD (PSSI-5 = 55, and cutoff is 23) and at the end of treatment (PSSI-5 = 17), and 3-month follow-up (PSSI-5 = 21), she had a negative diagnosis for PTSD. We reflect on the mediating effects that contextual factors such as gang violence had on the treatment process and the feasibility of implementing ESTs for PTSD in LMICs under conditions of ongoing adversity.
- Full Text:
- Date Issued: 2020
Integrative taxonomy reveals hidden diversity in the southern African darters genus Nannocharax Günther 1867 (Characiformes: Distichodontidae):
- Bragança, Pedro H N, Smith, Timothy G, Vreven, Emmanuel J W M N, Chakona, Albert
- Authors: Bragança, Pedro H N , Smith, Timothy G , Vreven, Emmanuel J W M N , Chakona, Albert
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163510 , vital:41044 , https://0-doi.org.wam.seals.ac.za/10.1111/jfb.14535
- Description: The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species.
- Full Text:
- Date Issued: 2020
- Authors: Bragança, Pedro H N , Smith, Timothy G , Vreven, Emmanuel J W M N , Chakona, Albert
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163510 , vital:41044 , https://0-doi.org.wam.seals.ac.za/10.1111/jfb.14535
- Description: The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species.
- Full Text:
- Date Issued: 2020
Integrative taxonomy reveals hidden diversity in the southern African darters genus Nannocharax Günther 1867 (Characiformes: Distichodontidae):
- Bragança, Pedro H N, Smith, Timothy G, Vreven, Emmanuel J W M N, Chakona, Albert
- Authors: Bragança, Pedro H N , Smith, Timothy G , Vreven, Emmanuel J W M N , Chakona, Albert
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163543 , vital:41047 , https://0-doi.org.wam.seals.ac.za/10.1111/jfb.14535
- Description: The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species.
- Full Text:
- Date Issued: 2020
- Authors: Bragança, Pedro H N , Smith, Timothy G , Vreven, Emmanuel J W M N , Chakona, Albert
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163543 , vital:41047 , https://0-doi.org.wam.seals.ac.za/10.1111/jfb.14535
- Description: The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species.
- Full Text:
- Date Issued: 2020
Intermediate disturbance promotes diversity and the conservation of dung beetles (Scarabaeoidea: Scarabaeidae and Aphodiidae) in the Eastern Cape, South Africa
- Tocco, Claudia, Midgley, John M, Villet, Martin H
- Authors: Tocco, Claudia , Midgley, John M , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442195 , vital:73966 , https://doi.org/10.1016/j.baae.2020.10.005
- Description: Environmental fluctuations, such as changes in climate, agricultural management and anthropogenic land-use patterns can affect the diversity of organisms inhabiting an area. Losses of biodiversity alter ecosystems processes, eroding their capacity to deliver ecosystem services. Dung beetles are critical ecosystem service providers, making them an ideal ecological indicator to explore the effects of land-use change on biodiversity. Dung beetles were sampled across three land-use types, in the summers of 2015 and 2016 in the Eastern Cape province, South Africa. Game ranching is regarded as a relatively low-intensity land use type. It was compared with cattle ranching (medium intensity) and dairy farming (high intensity) to examine their effect on dung beetle assemblage metrics (abundance, species richness and true Shannon diversity index), guild diversity (as nesting guilds) and spatial turnover. The intermediate grazing intensity of cattle ranching supported a higher abundance and diversity of both whole dung beetle assemblage and the nesting guilds, followed by the game ranches and then dairy farms. Differences between the sampling years were dependent on the beetle nesting guild, and largely correlated with rainfall and temperature. Cattle and game ranches shared a higher number of species than either shared with dairy farms. Whittaker's Beta-diversity index showed the highest species turnover between game ranches and dairy farms. A mix of game and cattle ranching, minimising dairy farming or restricting it to already ecological degraded sites, appears the best alternative for maintenance of dung beetle diversity and their ecosystem services. The year-to-year trends of the data were in general consistent, confirming that dung beetles are reliable ecological indicators; but also suggest that climate change that affects rainfall will result in the reduction of the abundance and diversity of this key ecological group.
- Full Text:
- Date Issued: 2020
- Authors: Tocco, Claudia , Midgley, John M , Villet, Martin H
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442195 , vital:73966 , https://doi.org/10.1016/j.baae.2020.10.005
- Description: Environmental fluctuations, such as changes in climate, agricultural management and anthropogenic land-use patterns can affect the diversity of organisms inhabiting an area. Losses of biodiversity alter ecosystems processes, eroding their capacity to deliver ecosystem services. Dung beetles are critical ecosystem service providers, making them an ideal ecological indicator to explore the effects of land-use change on biodiversity. Dung beetles were sampled across three land-use types, in the summers of 2015 and 2016 in the Eastern Cape province, South Africa. Game ranching is regarded as a relatively low-intensity land use type. It was compared with cattle ranching (medium intensity) and dairy farming (high intensity) to examine their effect on dung beetle assemblage metrics (abundance, species richness and true Shannon diversity index), guild diversity (as nesting guilds) and spatial turnover. The intermediate grazing intensity of cattle ranching supported a higher abundance and diversity of both whole dung beetle assemblage and the nesting guilds, followed by the game ranches and then dairy farms. Differences between the sampling years were dependent on the beetle nesting guild, and largely correlated with rainfall and temperature. Cattle and game ranches shared a higher number of species than either shared with dairy farms. Whittaker's Beta-diversity index showed the highest species turnover between game ranches and dairy farms. A mix of game and cattle ranching, minimising dairy farming or restricting it to already ecological degraded sites, appears the best alternative for maintenance of dung beetle diversity and their ecosystem services. The year-to-year trends of the data were in general consistent, confirming that dung beetles are reliable ecological indicators; but also suggest that climate change that affects rainfall will result in the reduction of the abundance and diversity of this key ecological group.
- Full Text:
- Date Issued: 2020
Misconceptions and misapplications of student-centered approaches
- Authors: McKenna, Sioux , Quinn, Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453507 , vital:75259 , ISBN 9780429259371 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780429259371-8/misconceptions-misapplications-student-centered-approaches-sioux-mckenna-lynn-quinn
- Description: A 1967 cartoon strip by Bud Blake shows a young boy, Tiger, telling his friend that he has taught his dog, Stripe, to whistle. “I don’t hear him whistling,” says the friend. Tiger explains “I said I taught him. I didn’t say he learned it.” Understanding education in terms of what it is that teachers do at the expense of a focus on how students learn has long been criticized. In 1916, Dewey was calling for more democratic approaches to education which took the student’s context into account. In 1968, Freire called for a major shift away from the “banking model” of education to one that recognized the student’s role in co-constructing knowledge. Despite the long history of such calls, transmission modes of teaching endure. It is thus unsurprising that calls for student-centered learning (SCL) are widespread.
- Full Text:
- Date Issued: 2020
- Authors: McKenna, Sioux , Quinn, Lynn
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453507 , vital:75259 , ISBN 9780429259371 , https://www.taylorfrancis.com/chapters/edit/10.4324/9780429259371-8/misconceptions-misapplications-student-centered-approaches-sioux-mckenna-lynn-quinn
- Description: A 1967 cartoon strip by Bud Blake shows a young boy, Tiger, telling his friend that he has taught his dog, Stripe, to whistle. “I don’t hear him whistling,” says the friend. Tiger explains “I said I taught him. I didn’t say he learned it.” Understanding education in terms of what it is that teachers do at the expense of a focus on how students learn has long been criticized. In 1916, Dewey was calling for more democratic approaches to education which took the student’s context into account. In 1968, Freire called for a major shift away from the “banking model” of education to one that recognized the student’s role in co-constructing knowledge. Despite the long history of such calls, transmission modes of teaching endure. It is thus unsurprising that calls for student-centered learning (SCL) are widespread.
- Full Text:
- Date Issued: 2020
New insights into the taxonomic status, distribution and natural history of De Witte's Clicking Frog (Kassinula wittei Laurent, 1940)
- Conradie, Werner C, Keates, Chad, Lobón-Rovira, Javier, Vaz Pinto, Pedro, Verburgt, Luke, Baptista, Ninda L, Harvey, James, Júlio, Timóteo
- Authors: Conradie, Werner C , Keates, Chad , Lobón-Rovira, Javier , Vaz Pinto, Pedro , Verburgt, Luke , Baptista, Ninda L , Harvey, James , Júlio, Timóteo
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443572 , vital:74134 , https://hdl.handle.net/10520/ejc-afzoo-v55-n4-a6
- Description: Kassinula is a monotypic genus of small frog in the family Hyperoliidae, only represented by Kassinula wittei. This species morphologically resembles both Kassina Girard, 1853 and Afrixalus Laurent, 1944, and its taxonomic status has been debated for decades. It has previously been subsumed within Kassina, and is currently placed as a sister genus to Afrixalus, although it has not been included in any phylogenetic studies until now. This species is poorly represented in museum collections and is only known from fewer than 35 specimens from southern Democratic Republic of the Congo and adjacent Zambia. Newly collected material from central Angola, a range extension of 400-800 km west of previously known localities, allowed us to revisit the taxonomic placement of the genus with the aid of phylogenetic analysis and shed light on its geographic distribution, morphology and natural history. Although our phylogenetic analysis is limited to a single mitochondrial gene (16S), we place Kassinula in the subfamily Hyperoliinae and closely related to Afrixalus, with a high degree of confidence. Further phylogenetic studies are needed before formally synonymising Afrixalus with Kassinula.
- Full Text:
- Date Issued: 2020
- Authors: Conradie, Werner C , Keates, Chad , Lobón-Rovira, Javier , Vaz Pinto, Pedro , Verburgt, Luke , Baptista, Ninda L , Harvey, James , Júlio, Timóteo
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/443572 , vital:74134 , https://hdl.handle.net/10520/ejc-afzoo-v55-n4-a6
- Description: Kassinula is a monotypic genus of small frog in the family Hyperoliidae, only represented by Kassinula wittei. This species morphologically resembles both Kassina Girard, 1853 and Afrixalus Laurent, 1944, and its taxonomic status has been debated for decades. It has previously been subsumed within Kassina, and is currently placed as a sister genus to Afrixalus, although it has not been included in any phylogenetic studies until now. This species is poorly represented in museum collections and is only known from fewer than 35 specimens from southern Democratic Republic of the Congo and adjacent Zambia. Newly collected material from central Angola, a range extension of 400-800 km west of previously known localities, allowed us to revisit the taxonomic placement of the genus with the aid of phylogenetic analysis and shed light on its geographic distribution, morphology and natural history. Although our phylogenetic analysis is limited to a single mitochondrial gene (16S), we place Kassinula in the subfamily Hyperoliinae and closely related to Afrixalus, with a high degree of confidence. Further phylogenetic studies are needed before formally synonymising Afrixalus with Kassinula.
- Full Text:
- Date Issued: 2020
Photodynamic antimicrobial chemotherapy of a dimethylamino-functionalized asymmetric zinc (II) phthalocyanine and its quaternized derivative against Staphylococcus aureus when supported on asymmetric polystyrene polymer membranes:
- Mafukidze, Donovan Musizvinoda Chidyamurimi, Nyokong, Tebello
- Authors: Mafukidze, Donovan Musizvinoda Chidyamurimi , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148595 , vital:38753 , https://doi.org/10.1016/j.reactfunctpolym.2020.104634
- Description: Membrane applications are hindered by fouling. Photoactive membranes (containing photosensitizers) show photodynamic antimicrobial chemotherapy (PACT) activity which reduces biological fouling. In this work we use phthalocyanines (Pcs) as photosensitizers. The Pcs used are: 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(dimethylamino) phthalocyaninato zinc(II) (1) and the quaternized 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(trimethylamino) phthalocyanine zinc(II) methyl sulfate (2). Complex 2 showed an enhanced singlet oxygen quantum yield (ΦΔ) of 0.76 compared to 0.53 for 1. Complex 2 showed enhanced PACT activity against Staphylococcus aureus giving a log reduction value of 9.4, while its precursor (complex 1) gave 0.08. The complexes were then conjugated to amine-functionalized polystyrene and embedded into polystyrene to form membranes resulting in ΦΔ values of 0.24 and 0.27 for complexes 1 and 2 respectively in water. The latter membrane showed better PACT activity.
- Full Text:
- Date Issued: 2020
- Authors: Mafukidze, Donovan Musizvinoda Chidyamurimi , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148595 , vital:38753 , https://doi.org/10.1016/j.reactfunctpolym.2020.104634
- Description: Membrane applications are hindered by fouling. Photoactive membranes (containing photosensitizers) show photodynamic antimicrobial chemotherapy (PACT) activity which reduces biological fouling. In this work we use phthalocyanines (Pcs) as photosensitizers. The Pcs used are: 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(dimethylamino) phthalocyaninato zinc(II) (1) and the quaternized 2-(4-carboxyphenoxy)-9(10), 16(17), 23(24)-tris(trimethylamino) phthalocyanine zinc(II) methyl sulfate (2). Complex 2 showed an enhanced singlet oxygen quantum yield (ΦΔ) of 0.76 compared to 0.53 for 1. Complex 2 showed enhanced PACT activity against Staphylococcus aureus giving a log reduction value of 9.4, while its precursor (complex 1) gave 0.08. The complexes were then conjugated to amine-functionalized polystyrene and embedded into polystyrene to form membranes resulting in ΦΔ values of 0.24 and 0.27 for complexes 1 and 2 respectively in water. The latter membrane showed better PACT activity.
- Full Text:
- Date Issued: 2020
Regularly drinking desert birds have greater evaporative cooling capacity and higher heat tolerance limits than non‐drinking species
- Czenze, Zenon J, Kemp, Ryno, van Jaarsveld, Barry, Freeman, Marc T, Smit, Ben, Wolf, Blair O, McKechnie, Andrew E
- Authors: Czenze, Zenon J , Kemp, Ryno , van Jaarsveld, Barry , Freeman, Marc T , Smit, Ben , Wolf, Blair O , McKechnie, Andrew E
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441585 , vital:73900 , https://doi.org/10.1111/1365-2435.13573
- Description: Surface water is a critical resource for many birds inhabiting arid re-gions, but the implications of regular drinking and dependence on sur-face water for the evolution of thermal physiology remain largely unex-plored. We hypothesized that avian thermoregulation in the heat has evolved in tandem with the use of surface water and predicted that (a) regularly drinking species have a greater capacity to elevate rates of evaporative water loss (EWL) compared to non‐drinking species, and (b) heat tolerance limits (HTLs) are higher among drinking species. To test these predictions, we quantified thermoregulatory responses to high air temperature (Ta) in 12 species of passerines from the South African arid zone and combined these with values for an additional five species. We categorized each species as either: (a) water‐dependent, regularly drinking, or (b) water‐independent, occasional‐/non‐drinking.
- Full Text:
- Date Issued: 2020
- Authors: Czenze, Zenon J , Kemp, Ryno , van Jaarsveld, Barry , Freeman, Marc T , Smit, Ben , Wolf, Blair O , McKechnie, Andrew E
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441585 , vital:73900 , https://doi.org/10.1111/1365-2435.13573
- Description: Surface water is a critical resource for many birds inhabiting arid re-gions, but the implications of regular drinking and dependence on sur-face water for the evolution of thermal physiology remain largely unex-plored. We hypothesized that avian thermoregulation in the heat has evolved in tandem with the use of surface water and predicted that (a) regularly drinking species have a greater capacity to elevate rates of evaporative water loss (EWL) compared to non‐drinking species, and (b) heat tolerance limits (HTLs) are higher among drinking species. To test these predictions, we quantified thermoregulatory responses to high air temperature (Ta) in 12 species of passerines from the South African arid zone and combined these with values for an additional five species. We categorized each species as either: (a) water‐dependent, regularly drinking, or (b) water‐independent, occasional‐/non‐drinking.
- Full Text:
- Date Issued: 2020
Rejection of the genetic implications of the “Abundant Centre Hypothesis” in marine mussels
- Ntuli, Noxolo N, Nicastro, Katy R, Zardi, Gerardo I, Assis, Jorge, McQuaid, Christopher D, Teske, Peter R
- Authors: Ntuli, Noxolo N , Nicastro, Katy R , Zardi, Gerardo I , Assis, Jorge , McQuaid, Christopher D , Teske, Peter R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444839 , vital:74302 , https://www.nature.com/articles/s41598-020-57474-0
- Description: The ‘Abundant-Centre Hypothesis’ is a well-established but controversial hypothesis stating that the abundance of a species is highest at the centre of its range and decreases towards the edges, where conditions are unfavourable. As genetic diversity depends on population size, edge populations are expected to show lower intra-population genetic diversity than core populations, while showing high inter-population genetic divergence. Here, the genetic implications of the Abundant-Centre Hypothesis were tested on two coastal mussels from South Africa that disperse by means of planktonic larvae, the native Perna perna and the invasive Mytilus galloprovincialis. Genetic structure was found within P. perna, which, together with evidence from Lagrangian particle simulations, points to significant reductions in gene flow between sites. Despite this, the expected diversity pattern between centre and edge populations was not found for either species. We conclude that the genetic predictions of the Abundant-Centre Hypothesis are unlikely to be met by high-dispersal species with large population sizes, and may only become evident in species with much lower levels of connectivity.
- Full Text:
- Date Issued: 2020
- Authors: Ntuli, Noxolo N , Nicastro, Katy R , Zardi, Gerardo I , Assis, Jorge , McQuaid, Christopher D , Teske, Peter R
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/444839 , vital:74302 , https://www.nature.com/articles/s41598-020-57474-0
- Description: The ‘Abundant-Centre Hypothesis’ is a well-established but controversial hypothesis stating that the abundance of a species is highest at the centre of its range and decreases towards the edges, where conditions are unfavourable. As genetic diversity depends on population size, edge populations are expected to show lower intra-population genetic diversity than core populations, while showing high inter-population genetic divergence. Here, the genetic implications of the Abundant-Centre Hypothesis were tested on two coastal mussels from South Africa that disperse by means of planktonic larvae, the native Perna perna and the invasive Mytilus galloprovincialis. Genetic structure was found within P. perna, which, together with evidence from Lagrangian particle simulations, points to significant reductions in gene flow between sites. Despite this, the expected diversity pattern between centre and edge populations was not found for either species. We conclude that the genetic predictions of the Abundant-Centre Hypothesis are unlikely to be met by high-dispersal species with large population sizes, and may only become evident in species with much lower levels of connectivity.
- Full Text:
- Date Issued: 2020
Sustainable conflict resolution through community based Water, Sanitation and Hygiene (WASH) Planning in fragile and conflict situations: the case of Somalia
- Mafuta, Wonder, Zuwarimwe, Jethro, Kamuzhanje, Joseph, Mwale, Marizvikuru, Chipaike, Ronald
- Authors: Mafuta, Wonder , Zuwarimwe, Jethro , Kamuzhanje, Joseph , Mwale, Marizvikuru , Chipaike, Ronald
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150241 , vital:38952 , https://0-doi.org.wam.seals.ac.za/10.1177/0021909620928104
- Description: The study examines the nature of disputes, which are prevalent in water, sanitation and hygiene (WASH) programming and suggests possible conflict management and resolution mechanisms. An online web-based survey, hosted on the popular Survey Monkey platform, was conducted through the Somalia WASH Cluster to 40 ‘active’ member organisations. A response rate of 73% was achieved. Thematic analysis was conducted using NVivo 12. The type of conflicts identified are as follows: visible versus non-visible benefits, emergency versus development focus, the young and the old, insiders versus outsiders, local versus donor priorities and men versus women. The article goes on to suggest possible conflict resolution mechanisms, which include: planning together with communities, continuum programming, setting up early warning systems, harmonisation of institutions managing WASH resources and the development of localised Memorandums of Understanding. It is recommended that the complexities of conflict and fragility require different approaches. The approaches would apply to both relief and developmental WASH programming.
- Full Text:
- Date Issued: 2020
- Authors: Mafuta, Wonder , Zuwarimwe, Jethro , Kamuzhanje, Joseph , Mwale, Marizvikuru , Chipaike, Ronald
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150241 , vital:38952 , https://0-doi.org.wam.seals.ac.za/10.1177/0021909620928104
- Description: The study examines the nature of disputes, which are prevalent in water, sanitation and hygiene (WASH) programming and suggests possible conflict management and resolution mechanisms. An online web-based survey, hosted on the popular Survey Monkey platform, was conducted through the Somalia WASH Cluster to 40 ‘active’ member organisations. A response rate of 73% was achieved. Thematic analysis was conducted using NVivo 12. The type of conflicts identified are as follows: visible versus non-visible benefits, emergency versus development focus, the young and the old, insiders versus outsiders, local versus donor priorities and men versus women. The article goes on to suggest possible conflict resolution mechanisms, which include: planning together with communities, continuum programming, setting up early warning systems, harmonisation of institutions managing WASH resources and the development of localised Memorandums of Understanding. It is recommended that the complexities of conflict and fragility require different approaches. The approaches would apply to both relief and developmental WASH programming.
- Full Text:
- Date Issued: 2020
The roles of phonological awareness, rapid automatised naming and morphological awareness in isiXhosa:
- Schaefer, Maxine, Probert, Tracy N, Rees, Siȃn
- Authors: Schaefer, Maxine , Probert, Tracy N , Rees, Siȃn
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159950 , vital:40359 , https://doi.org/10.5785/36-1-878
- Description: The current paper examines the unique contributions of phonological awareness (PA), rapid automatised naming (RAN) and morphological awareness (MA) to oral reading fluency (ORF) in isiXhosa. No published study has yet explored the individual contributions of these three cognitive-linguistic skills to reading in isiXhosa. Sixty-six grade 3 home language isiXhosa learners were assessed on these cognitive-linguistic skills. Results from a linear regression analysis showed that only RAN and MA, but not PA, were significant concurrent predictors of ORF. These results suggest that the role of PA in reading in grade 3 learners in isiXhosa may have been overestimated because other important predictors of reading have not been controlled. Our data also suggest that grade 3 isiXhosa learners may make use of the morpheme as a grain size in reading. Our study highlights the need for longitudinal research which explores the roles of PA, MA and RAN in reading development in order to inform reading pedagogy in isiXhosa and other Southern Bantu languages.
- Full Text:
- Date Issued: 2020
- Authors: Schaefer, Maxine , Probert, Tracy N , Rees, Siȃn
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/159950 , vital:40359 , https://doi.org/10.5785/36-1-878
- Description: The current paper examines the unique contributions of phonological awareness (PA), rapid automatised naming (RAN) and morphological awareness (MA) to oral reading fluency (ORF) in isiXhosa. No published study has yet explored the individual contributions of these three cognitive-linguistic skills to reading in isiXhosa. Sixty-six grade 3 home language isiXhosa learners were assessed on these cognitive-linguistic skills. Results from a linear regression analysis showed that only RAN and MA, but not PA, were significant concurrent predictors of ORF. These results suggest that the role of PA in reading in grade 3 learners in isiXhosa may have been overestimated because other important predictors of reading have not been controlled. Our data also suggest that grade 3 isiXhosa learners may make use of the morpheme as a grain size in reading. Our study highlights the need for longitudinal research which explores the roles of PA, MA and RAN in reading development in order to inform reading pedagogy in isiXhosa and other Southern Bantu languages.
- Full Text:
- Date Issued: 2020
An Illustration of a Deductive Pattern Matching Procedure in Qualitative Leadership Research:
- Authors: Pearse, Noel J
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149895 , vital:38911 , DOI: 10.34190/JBRM.17.3.004
- Description: Most qualitative studies in business-related research have adopted an inductive approach, in that they explore specific cases and then extract themes, or statements that are more general, from this data. This approach has its shortcomings, including not developing a more systematic body of knowledge of behavioural and social processes that take place in organisations. In contrast, in deductive qualitative research, the theoretical propositions derived from a review of the literature serve as its departure point, informing how the data is collected. Later on in the analysis of data, the researcher uses the propositions to determine if the literature explains the case that was being investigated. Unfortunately, given the relative neglect of deductive qualitative research approaches, there is little guidance and few examples offered that illustrate the application of these techniques. This poses a challenge for researchers, who often need a greater level of structure when it comes to designing and conducting their research. Therefore, the aim of this paper is to illustrate the design of a research protocol that integrates two deductive approaches that are suitable for explanatory case study research, namely deductive thematic analysis and pattern matching. This paper develops a sevenstep process that researchers can follow, for carrying out this type of deductive qualitative research. Using extracts from a research study investigating the leading of organisational change, the steps in this process are illustrated.
- Full Text:
- Date Issued: 2019
- Authors: Pearse, Noel J
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149895 , vital:38911 , DOI: 10.34190/JBRM.17.3.004
- Description: Most qualitative studies in business-related research have adopted an inductive approach, in that they explore specific cases and then extract themes, or statements that are more general, from this data. This approach has its shortcomings, including not developing a more systematic body of knowledge of behavioural and social processes that take place in organisations. In contrast, in deductive qualitative research, the theoretical propositions derived from a review of the literature serve as its departure point, informing how the data is collected. Later on in the analysis of data, the researcher uses the propositions to determine if the literature explains the case that was being investigated. Unfortunately, given the relative neglect of deductive qualitative research approaches, there is little guidance and few examples offered that illustrate the application of these techniques. This poses a challenge for researchers, who often need a greater level of structure when it comes to designing and conducting their research. Therefore, the aim of this paper is to illustrate the design of a research protocol that integrates two deductive approaches that are suitable for explanatory case study research, namely deductive thematic analysis and pattern matching. This paper develops a sevenstep process that researchers can follow, for carrying out this type of deductive qualitative research. Using extracts from a research study investigating the leading of organisational change, the steps in this process are illustrated.
- Full Text:
- Date Issued: 2019
Comparative study of skipjack tuna Katsuwonus pelamis (Scombridae) fishery stocks from the South Atlantic and western Indian oceans
- Dahlet, Lol I, Downey-Breedt, Nicola, Arce, Gabriel, Sauer, Warwick H H, Gasalla, Maria A
- Authors: Dahlet, Lol I , Downey-Breedt, Nicola , Arce, Gabriel , Sauer, Warwick H H , Gasalla, Maria A
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123988 , vital:35523 , https://doi.org/10.3989/scimar.04804.22C
- Description: Temporal and spatial fluctuations in the abundance of oceanic pelagic populations spread geographically around the globe are common (Cushing 1975). The causes of these fluctuations may be exogenous (environmental or anthropogenic) or endogenous to the organism (e.g. ontogenetic drivers) (Ricker 1954). This scenario applies to some tuna stocks, including the skipjack tuna, Katsuwonus pelamis (Linnaeus, 1758), known as bonito-listrado in Brazil, katunkel, or ocean bonito in South Africa, and godhaa (bigger) or kadumas (smaller) skipjack in the Maldives. The skipjack belongs to the family Scombridae and inhabits tropical and subtropical areas of the globe. On average, 85% of skipjack catch occurs in waters warmer than 24°C (Fonteneau 2003). This resource is of particular importance, accounting for 57% of the global industrial tuna catch in 2016, and is mainly processed by the canning industry. Skipjack catches totaled 2.79 million t in 2016 (ISSF 2018), and currently 8.5% of worldwide catches are made by the pole-and line fleet. In Brazil and the Maldives, the resource is well-known. Catches in Brazil were seen to increase until 2014, while in the Maldives, 2006 marked the beginning of a strong and unsettling decline that continued until recent years. Off South Africa, skipjack catches are 1000 to 10000 times lower than those from Brazil and the Maldives, and the highest catches were recorded in 2012.
- Full Text:
- Date Issued: 2019
- Authors: Dahlet, Lol I , Downey-Breedt, Nicola , Arce, Gabriel , Sauer, Warwick H H , Gasalla, Maria A
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123988 , vital:35523 , https://doi.org/10.3989/scimar.04804.22C
- Description: Temporal and spatial fluctuations in the abundance of oceanic pelagic populations spread geographically around the globe are common (Cushing 1975). The causes of these fluctuations may be exogenous (environmental or anthropogenic) or endogenous to the organism (e.g. ontogenetic drivers) (Ricker 1954). This scenario applies to some tuna stocks, including the skipjack tuna, Katsuwonus pelamis (Linnaeus, 1758), known as bonito-listrado in Brazil, katunkel, or ocean bonito in South Africa, and godhaa (bigger) or kadumas (smaller) skipjack in the Maldives. The skipjack belongs to the family Scombridae and inhabits tropical and subtropical areas of the globe. On average, 85% of skipjack catch occurs in waters warmer than 24°C (Fonteneau 2003). This resource is of particular importance, accounting for 57% of the global industrial tuna catch in 2016, and is mainly processed by the canning industry. Skipjack catches totaled 2.79 million t in 2016 (ISSF 2018), and currently 8.5% of worldwide catches are made by the pole-and line fleet. In Brazil and the Maldives, the resource is well-known. Catches in Brazil were seen to increase until 2014, while in the Maldives, 2006 marked the beginning of a strong and unsettling decline that continued until recent years. Off South Africa, skipjack catches are 1000 to 10000 times lower than those from Brazil and the Maldives, and the highest catches were recorded in 2012.
- Full Text:
- Date Issued: 2019
Developing Namibian Grade 8 Learners’ Conceptions of Fractions Using Visual Models
- Albin, Simon, Brown, Bruce J L
- Authors: Albin, Simon , Brown, Bruce J L
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/483706 , vital:78788 , https://doi.org/10.1080/18117295.2019.1658443
- Description: Learning rational number concepts is acknowledged as an important task but many learners find it difficult to make sense of them. This paper reports on a case study of the learning in a short (nine-lesson) learning programme for Grade 8 learners in a Namibian school, which sought to use visual models (circle area, bar area and number line) to deepen learners’ understanding of fractions as a means to represent rational quantities. The initial benchmark test indicated a number of ways of working with fraction representations, many of which were inappropriate to the rational quantity presented. Although most learners were able to use a fraction to appropriately describe a part–whole area diagram with a single whole, few were able to appropriately label a similar diagram with multiple wholes, or a quantity greater than 1 on the number line. In the learning programme learners worked with visual models that incorporated multiple reference wholes, to explicitly identify the reference whole, to quantify the size of appropriately subdivided units using unit fraction names and to use these units in a measurement process to quantify the quantities these models indicated. A final test showed a sound conceptualisation of the use of fractions to represent rational quantities less than and greater than 1, in such models.
- Full Text:
- Date Issued: 2019
- Authors: Albin, Simon , Brown, Bruce J L
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/483706 , vital:78788 , https://doi.org/10.1080/18117295.2019.1658443
- Description: Learning rational number concepts is acknowledged as an important task but many learners find it difficult to make sense of them. This paper reports on a case study of the learning in a short (nine-lesson) learning programme for Grade 8 learners in a Namibian school, which sought to use visual models (circle area, bar area and number line) to deepen learners’ understanding of fractions as a means to represent rational quantities. The initial benchmark test indicated a number of ways of working with fraction representations, many of which were inappropriate to the rational quantity presented. Although most learners were able to use a fraction to appropriately describe a part–whole area diagram with a single whole, few were able to appropriately label a similar diagram with multiple wholes, or a quantity greater than 1 on the number line. In the learning programme learners worked with visual models that incorporated multiple reference wholes, to explicitly identify the reference whole, to quantify the size of appropriately subdivided units using unit fraction names and to use these units in a measurement process to quantify the quantities these models indicated. A final test showed a sound conceptualisation of the use of fractions to represent rational quantities less than and greater than 1, in such models.
- Full Text:
- Date Issued: 2019
Development of high yielding strain of Pleurotus tuber-regium fructification, nutritional and phylogenetic studies
- Bamigboye, Comfort O, Oloke, Julius K, Dames, Joanna F
- Authors: Bamigboye, Comfort O , Oloke, Julius K , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448595 , vital:74745 , https://doi.org/10.1007/s13197-019-03786-7
- Description: Mushrooms are nutritionally rich, healthy and medicinal. Pleurotus tuber-regium (Fr.) is one of the nutritious medicinal mushroom found in the tropics and subtropics, but with history of slow growth and low sclerotia yield. In this study, mutants were created by mycelia exposure to ultraviolet irradiation (at a wavelength of 254 nm and a distance of 45 cm), for 3 h and sub-cultured at 30 min interval. The DNA from the wild and mutant strains were extracted, PCR amplified and sequenced. A phylogenetic tree was constructed to show the degree of similarity and differences between the wild and the mutant strains. Fructification studies were conducted on Rhodes grass straw and sawdust to determine the viability of the mutant strains and any nutritional improvement. The wild strain of P. tuber-regium and mutant produced at 30 min (Pt30) cultivated on sawdust and Rhodes straw, yielded sclerotia with biological efficiency of 8.8 and 47.6% respectively. Proximate analysis of the sclerotium showed that the mutant, Pt30, had improved nutritional compositions compared to the wild strain with a total non-structural carbohydrate concentration of 2.41 g as against 0.93 g. Conclusively in this study, better strains of P. tuber-regium were produced with faster growth rate, higher mycelia ramification rate on lignocellulosic substrate and a higher sclerotia yield than the wild P. tuber-regium. It was also established that mutagenesis is capable of improving P. tuber-regium for a successful commercial venture in sclerotia production.
- Full Text:
- Date Issued: 2019
- Authors: Bamigboye, Comfort O , Oloke, Julius K , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448595 , vital:74745 , https://doi.org/10.1007/s13197-019-03786-7
- Description: Mushrooms are nutritionally rich, healthy and medicinal. Pleurotus tuber-regium (Fr.) is one of the nutritious medicinal mushroom found in the tropics and subtropics, but with history of slow growth and low sclerotia yield. In this study, mutants were created by mycelia exposure to ultraviolet irradiation (at a wavelength of 254 nm and a distance of 45 cm), for 3 h and sub-cultured at 30 min interval. The DNA from the wild and mutant strains were extracted, PCR amplified and sequenced. A phylogenetic tree was constructed to show the degree of similarity and differences between the wild and the mutant strains. Fructification studies were conducted on Rhodes grass straw and sawdust to determine the viability of the mutant strains and any nutritional improvement. The wild strain of P. tuber-regium and mutant produced at 30 min (Pt30) cultivated on sawdust and Rhodes straw, yielded sclerotia with biological efficiency of 8.8 and 47.6% respectively. Proximate analysis of the sclerotium showed that the mutant, Pt30, had improved nutritional compositions compared to the wild strain with a total non-structural carbohydrate concentration of 2.41 g as against 0.93 g. Conclusively in this study, better strains of P. tuber-regium were produced with faster growth rate, higher mycelia ramification rate on lignocellulosic substrate and a higher sclerotia yield than the wild P. tuber-regium. It was also established that mutagenesis is capable of improving P. tuber-regium for a successful commercial venture in sclerotia production.
- Full Text:
- Date Issued: 2019