Cytotoxicity, phytochemical analysis and antioxidant activity of crude extracts from Rhizomes of Elephantorrhiza Elephantina and Pentanisia Prunelloides
- Mpofu, Smart J, Msagati, Titus A M, Krause, Rui W M
- Authors: Mpofu, Smart J , Msagati, Titus A M , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125097 , vital:35728 , https://doi.org/10.4314/ajtcam.v11i1.6
- Description: Background: Elephantorrhiza elephantina (Ee) and Pentanisia prunelloides (Pp) are two medicinal plants which are widely used to remedy various ailments including diarrhoea, dysentery, inflammation, fever, rheumatism, heartburn, tuberculosis, haemorrhoids, skin diseases, perforated peptic ulcers and sore joints in southern Africa (South Africa, Swaziland, Botswana and Zimbabwe). The following study was conducted to explore the in vitro cytotoxicity, antioxidant properties and phytochemical profile of the two medicinal plants. Materials and Methods: The cytotoxicity of the aqueous and methanol extracts and fractions of both species was studied using the brine shrimp lethality tests (BST) for the first time. Results: The results demonstrated that the lethality (LC50) for crude extracts for both plants ranged between 1.8 and 5.8 ppm and was relatively greater than that for the methanol, ethyl acetate and chloroform fractions of the extracts which ranged between 2.1 ppm and 27 ppm. This suggested that crude extracts were more potent than their respective fractions, further explaining that the different fractions of phytochemicals in these plant species work jointly (in synergy) to exert their therapeutic efficacy. Both aqueous and methanol extracts of the two medicinal plants demonstrated a high degree of antioxidant capacity against the DPPH radical with the Duh and Yen inhibition percentage ranging between 4.5% and 72%. Phytochemical studies of the rhizome extracts showed that the major compounds present include flavonoids, tannins, anthocyanidins, anthraquinones, triterpenoids (oleanolic acid), the steroidal saponin Diosgenin, the sugars, rhamnose, glucuronic acid, Arabinose and hexoses. Conclusion: This is the first report of the detection and isolation of diosgenin and oleanolic acid from the rhizome extracts of Ee and Pp. All structures were determined using spectroscopic/spectrometric techniques (1H NMR and 13C and LC-ESI-MS) and by comparison with literature data.
- Full Text:
- Date Issued: 2014
- Authors: Mpofu, Smart J , Msagati, Titus A M , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125097 , vital:35728 , https://doi.org/10.4314/ajtcam.v11i1.6
- Description: Background: Elephantorrhiza elephantina (Ee) and Pentanisia prunelloides (Pp) are two medicinal plants which are widely used to remedy various ailments including diarrhoea, dysentery, inflammation, fever, rheumatism, heartburn, tuberculosis, haemorrhoids, skin diseases, perforated peptic ulcers and sore joints in southern Africa (South Africa, Swaziland, Botswana and Zimbabwe). The following study was conducted to explore the in vitro cytotoxicity, antioxidant properties and phytochemical profile of the two medicinal plants. Materials and Methods: The cytotoxicity of the aqueous and methanol extracts and fractions of both species was studied using the brine shrimp lethality tests (BST) for the first time. Results: The results demonstrated that the lethality (LC50) for crude extracts for both plants ranged between 1.8 and 5.8 ppm and was relatively greater than that for the methanol, ethyl acetate and chloroform fractions of the extracts which ranged between 2.1 ppm and 27 ppm. This suggested that crude extracts were more potent than their respective fractions, further explaining that the different fractions of phytochemicals in these plant species work jointly (in synergy) to exert their therapeutic efficacy. Both aqueous and methanol extracts of the two medicinal plants demonstrated a high degree of antioxidant capacity against the DPPH radical with the Duh and Yen inhibition percentage ranging between 4.5% and 72%. Phytochemical studies of the rhizome extracts showed that the major compounds present include flavonoids, tannins, anthocyanidins, anthraquinones, triterpenoids (oleanolic acid), the steroidal saponin Diosgenin, the sugars, rhamnose, glucuronic acid, Arabinose and hexoses. Conclusion: This is the first report of the detection and isolation of diosgenin and oleanolic acid from the rhizome extracts of Ee and Pp. All structures were determined using spectroscopic/spectrometric techniques (1H NMR and 13C and LC-ESI-MS) and by comparison with literature data.
- Full Text:
- Date Issued: 2014
Activated carbon from lignocellulosic waste residues: effect of activating agent on porosity characteristics and use as adsorbents for organic species
- Olorundare, O F, Okonkwo, J O, Msagati, T A M, Mamba, Bhekie B, Krause, Rui W M
- Authors: Olorundare, O F , Okonkwo, J O , Msagati, T A M , Mamba, Bhekie B , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125233 , vital:35748 , https://doi.org/10.1007/s11270-014-1876-2
- Description: This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m2/g) and a large pore volume (1.592 cm3/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.
- Full Text:
- Date Issued: 2014
- Authors: Olorundare, O F , Okonkwo, J O , Msagati, T A M , Mamba, Bhekie B , Krause, Rui W M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125233 , vital:35748 , https://doi.org/10.1007/s11270-014-1876-2
- Description: This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m2/g) and a large pore volume (1.592 cm3/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.
- Full Text:
- Date Issued: 2014
Composite polyester membranes with embedded dendrimer hosts and bimetallic Fe/Ni nanoparticles: synthesis, characterisation and application to water treatment
- Malinga, S P, Arotiba, O A, Mapolie, S F, Krause, Rui W M, Mamba, Bhekie B, Diallo, M S
- Authors: Malinga, S P , Arotiba, O A , Mapolie, S F , Krause, Rui W M , Mamba, Bhekie B , Diallo, M S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125086 , vital:35727 , https://doi.org/10.1007/s11051-013-1698-y
- Description: This study describes the preparation, characterization and evaluation of new composite membranes with embedded dendrimer hosts and Fe/Ni nanoparticles. These new reactive membranes consist of films of cyclodextrin–poly(propyleneimine) dendrimers (β-CD–PPI) that are deposited onto commercial polysulfone microporous supports and crosslinked with trimesoyl chloride (TMC). The membranes were subsequently loaded with Fe/Ni nanoparticles and evaluated as separation/reactive media in aqueous solutions using 2,4,6-trichlorophenol as model pollutant. The morphology and physicochemical properties of the composite membranes were characterised using high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy and measurements of contact angle, water intake, porosity and water permeability. The sorption capacity and catalytic activity of the membranes were evaluated using ion chromatography, atmospheric pressure chemical ionisation-mass spectrometry and UV–Vis spectroscopy (UV–Vis). The sizes of the embedded Fe/Ni nanoparticles in the membranes ranged from 40 to 66 nm as confirmed by HR-TEM. The reaction rates for the dechlorination of 2,4,6-trichlorophenol ranged from 0.00148 to 0.00250 min−1. In all cases, we found that the reaction by-products consisted of chloride ions and mixtures of compounds including phenol (m/z = 93), 2,4-dichlorophenol (m/z = 163) and 4-chlorophenol (m/z = 128). The overall results of this study suggest that β-CD–PPI dendrimers are promising building blocks for the synthesis of composite and reactive membranes for the efficient removal of chlorinated organic pollutants from water.
- Full Text:
- Date Issued: 2013
- Authors: Malinga, S P , Arotiba, O A , Mapolie, S F , Krause, Rui W M , Mamba, Bhekie B , Diallo, M S
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125086 , vital:35727 , https://doi.org/10.1007/s11051-013-1698-y
- Description: This study describes the preparation, characterization and evaluation of new composite membranes with embedded dendrimer hosts and Fe/Ni nanoparticles. These new reactive membranes consist of films of cyclodextrin–poly(propyleneimine) dendrimers (β-CD–PPI) that are deposited onto commercial polysulfone microporous supports and crosslinked with trimesoyl chloride (TMC). The membranes were subsequently loaded with Fe/Ni nanoparticles and evaluated as separation/reactive media in aqueous solutions using 2,4,6-trichlorophenol as model pollutant. The morphology and physicochemical properties of the composite membranes were characterised using high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy and measurements of contact angle, water intake, porosity and water permeability. The sorption capacity and catalytic activity of the membranes were evaluated using ion chromatography, atmospheric pressure chemical ionisation-mass spectrometry and UV–Vis spectroscopy (UV–Vis). The sizes of the embedded Fe/Ni nanoparticles in the membranes ranged from 40 to 66 nm as confirmed by HR-TEM. The reaction rates for the dechlorination of 2,4,6-trichlorophenol ranged from 0.00148 to 0.00250 min−1. In all cases, we found that the reaction by-products consisted of chloride ions and mixtures of compounds including phenol (m/z = 93), 2,4-dichlorophenol (m/z = 163) and 4-chlorophenol (m/z = 128). The overall results of this study suggest that β-CD–PPI dendrimers are promising building blocks for the synthesis of composite and reactive membranes for the efficient removal of chlorinated organic pollutants from water.
- Full Text:
- Date Issued: 2013
Human DNAJ in cancer and stem cells:
- Sterrenberg, Jason N, Edkins, Adrienne L, Blatch, Gregory L
- Authors: Sterrenberg, Jason N , Edkins, Adrienne L , Blatch, Gregory L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165118 , vital:41210 , DOI: 10.1016/j.canlet.2011.08.019
- Description: The heat shock protein 40 kDa (HSP40/DNAJ) co-chaperones constitute the largest and most diverse sub-group of the heat shock protein (HSP) family. DNAJ are widely accepted as regulators of HSP70 function, but also have roles as co-chaperones for the HSP90 chaperone machine, and a growing number of biological functions that may be independent of either of these chaperones. The DNAJ proteins are differentially expressed in human tissues and demonstrate the capacity to function to both promote and suppress cancer development by acting as chaperones for tumour suppressors or oncoproteins. We review the current literature on the function and expression of DNAJ in cancer, stem cells and cancer stem cells. Combining data from gene expression, proteomics and studies in other systems, we propose that DNAJ will be key regulators of cancer, stem cell and possibly cancer stem cell function. The diversity of DNAJ and their assorted roles in a range of biological functions means that selected DNAJ, provided there is limited redundancy and that a specific link to malignancy can be established, may yet provide an attractive target for specific and selective drug design for the development of anti-cancer treatments.
- Full Text:
- Date Issued: 2011
- Authors: Sterrenberg, Jason N , Edkins, Adrienne L , Blatch, Gregory L
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165118 , vital:41210 , DOI: 10.1016/j.canlet.2011.08.019
- Description: The heat shock protein 40 kDa (HSP40/DNAJ) co-chaperones constitute the largest and most diverse sub-group of the heat shock protein (HSP) family. DNAJ are widely accepted as regulators of HSP70 function, but also have roles as co-chaperones for the HSP90 chaperone machine, and a growing number of biological functions that may be independent of either of these chaperones. The DNAJ proteins are differentially expressed in human tissues and demonstrate the capacity to function to both promote and suppress cancer development by acting as chaperones for tumour suppressors or oncoproteins. We review the current literature on the function and expression of DNAJ in cancer, stem cells and cancer stem cells. Combining data from gene expression, proteomics and studies in other systems, we propose that DNAJ will be key regulators of cancer, stem cell and possibly cancer stem cell function. The diversity of DNAJ and their assorted roles in a range of biological functions means that selected DNAJ, provided there is limited redundancy and that a specific link to malignancy can be established, may yet provide an attractive target for specific and selective drug design for the development of anti-cancer treatments.
- Full Text:
- Date Issued: 2011
Cancer stem cells in breast cancer and metastasis:
- Lawson, Jessica C, Blatch, Gregory L, Edkins, Adrienne L
- Authors: Lawson, Jessica C , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165057 , vital:41205 , DOI: 10.1007/s10549-009-0524-9
- Description: The cancer stem cell theory poses that cancers develop from a subset of malignant cells that possess stem cell characteristics and has been proposed to account for the development of a variety of malignancies, including breast cancer. These cancer stem cells (CSC) possess characteristics of both stem cells and cancer cells, in that they have the properties of self-renewal, asymmetric cell division, resistance to apoptosis, independent growth, tumourigenicity and metastatic potential. A CSC origin for breast cancer can neatly explain both the heterogeneity of breast cancers and the relapse of the tumours after treatment. However, many reports on CSC in the breast are contradictory. There is variation with respect to how breast cancer stem cells should be identified, their characteristics and a possible lack of correlation between clinical outcome and breast cancer stem cell status of a tumour. These combined factors have made breast cancer stem cells a highly contentious issue. In this review, we highlight the progress in the analysis of cancer stem cells, with an emphasis on breast cancer.
- Full Text:
- Date Issued: 2009
- Authors: Lawson, Jessica C , Blatch, Gregory L , Edkins, Adrienne L
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165057 , vital:41205 , DOI: 10.1007/s10549-009-0524-9
- Description: The cancer stem cell theory poses that cancers develop from a subset of malignant cells that possess stem cell characteristics and has been proposed to account for the development of a variety of malignancies, including breast cancer. These cancer stem cells (CSC) possess characteristics of both stem cells and cancer cells, in that they have the properties of self-renewal, asymmetric cell division, resistance to apoptosis, independent growth, tumourigenicity and metastatic potential. A CSC origin for breast cancer can neatly explain both the heterogeneity of breast cancers and the relapse of the tumours after treatment. However, many reports on CSC in the breast are contradictory. There is variation with respect to how breast cancer stem cells should be identified, their characteristics and a possible lack of correlation between clinical outcome and breast cancer stem cell status of a tumour. These combined factors have made breast cancer stem cells a highly contentious issue. In this review, we highlight the progress in the analysis of cancer stem cells, with an emphasis on breast cancer.
- Full Text:
- Date Issued: 2009
Aesthetic and spiritual ecosystem services provided by urban sacred sites
- De Lacy, Peter J G, Shackleton, Charlie M
- Authors: De Lacy, Peter J G , Shackleton, Charlie M
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60919 , vital:27891 , http://dx.doi.org/10.3390/su9091628
- Description: The range and use of ecosystem services provided by urban sacred sites has hardly been considered in studies of urban ecology, sustainability and human wellbeing. This paper examines the perceived ecosystem services supplied by green spaces or gardens associated with places of religious worship and appreciated by worshippers in a mid-sized town in South Africa. A questionnaire with open, closed and Likert scale questions was administered at 30 places of worship (25 with gardens and five without). Respondents identified a wide diversity of ecosystem services provided by gardens, with social ones being more recognized than ecological, and economic services the least. Approximately two-thirds of respondents visited a sacred site garden weekly or more often. The majority of respondents (96%) felt that a garden was necessary because it added to their feelings of connection with God, or helped them relax and so be better able to concentrate, and 54% stated that a garden enhanced their overall spiritual experience. Regression analysis revealed that aesthetic appreciation of a garden was significantly related to woody plant species richness, number and basal area in the garden. On the other hand, spiritual experience was positively related to woody plant basal area, but not species richness nor tree number. Neither size of the garden, nor number of years the respondents had been vising a particular sacred site had any influence on the rated spiritual or aesthetic experiences. These results reveal the widely appreciated ecosystem services provided by urban sacred spaces and their centrality in enhancing spiritual satisfaction for some.
- Full Text:
- Date Issued: 2017
- Authors: De Lacy, Peter J G , Shackleton, Charlie M
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60919 , vital:27891 , http://dx.doi.org/10.3390/su9091628
- Description: The range and use of ecosystem services provided by urban sacred sites has hardly been considered in studies of urban ecology, sustainability and human wellbeing. This paper examines the perceived ecosystem services supplied by green spaces or gardens associated with places of religious worship and appreciated by worshippers in a mid-sized town in South Africa. A questionnaire with open, closed and Likert scale questions was administered at 30 places of worship (25 with gardens and five without). Respondents identified a wide diversity of ecosystem services provided by gardens, with social ones being more recognized than ecological, and economic services the least. Approximately two-thirds of respondents visited a sacred site garden weekly or more often. The majority of respondents (96%) felt that a garden was necessary because it added to their feelings of connection with God, or helped them relax and so be better able to concentrate, and 54% stated that a garden enhanced their overall spiritual experience. Regression analysis revealed that aesthetic appreciation of a garden was significantly related to woody plant species richness, number and basal area in the garden. On the other hand, spiritual experience was positively related to woody plant basal area, but not species richness nor tree number. Neither size of the garden, nor number of years the respondents had been vising a particular sacred site had any influence on the rated spiritual or aesthetic experiences. These results reveal the widely appreciated ecosystem services provided by urban sacred spaces and their centrality in enhancing spiritual satisfaction for some.
- Full Text:
- Date Issued: 2017
The Legacy Effects of Colonial and Apartheid Imprints on Urban Greening in South Africa: Spaces, Species, and Suitability
- Shackleton, Charlie M, Gwedla, Nanamhla
- Authors: Shackleton, Charlie M , Gwedla, Nanamhla
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176296 , vital:42682 , https://doi.org/10.3389/fevo.2020.579813
- Description: Colonialism is a significant legacy across most aspects of urban form, the nature and distribution of public green spaces, and tree species composition in many cities of the Global South. However, the legacy effects of colonialism on urban green infrastructure and the uses thereof have only recently come under scrutiny. Here we collate information from South Africa on urban greening and interpret it through a colonial and apartheid legacy lens in relation to the distribution and types of urban nature found and their resonance with contemporary needs as an African country.
- Full Text:
- Date Issued: 2020
- Authors: Shackleton, Charlie M , Gwedla, Nanamhla
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/176296 , vital:42682 , https://doi.org/10.3389/fevo.2020.579813
- Description: Colonialism is a significant legacy across most aspects of urban form, the nature and distribution of public green spaces, and tree species composition in many cities of the Global South. However, the legacy effects of colonialism on urban green infrastructure and the uses thereof have only recently come under scrutiny. Here we collate information from South Africa on urban greening and interpret it through a colonial and apartheid legacy lens in relation to the distribution and types of urban nature found and their resonance with contemporary needs as an African country.
- Full Text:
- Date Issued: 2020
Establishment of translocated populations of smallmouth yellowfish, Labeobarbus aeneus (Pisces: Cyprinidae), in lentic and lotic habitats in the Great Fish River system, South Africa
- Weyl, Olaf L F, Stadtlander, Timo, Booth, Anthony J
- Authors: Weyl, Olaf L F , Stadtlander, Timo , Booth, Anthony J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124418 , vital:35607 , https://doi.org/10.3377/004.044.0109
- Description: As a result of numerous introductions and translocations of fishes, South Africa has recently been identified as a fish invasion hotspot (Leprieur et al. 2008). In freshwater ecosystems invasion by alien species is considered a leading mechanism driving environmental change (Clavero & Garcia- Berthou 2005; Garcia-Berthou et al. 2005). In South Africa, documented effects of fish invasions include the extirpation of indigenous fishes through predation (Cambray 2003), changes in invertebrate community structure (Lowe et al. 2008) and hybridization (Canonico et al. 2005). As a result, the management of alien species is a high national priority (National Environmental Management: Biodiversity Act 2004). Such management requires an understanding of the biology, ecology and establishment success of fishes outside their native range.
- Full Text:
- Date Issued: 2009
- Authors: Weyl, Olaf L F , Stadtlander, Timo , Booth, Anthony J
- Date: 2009
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124418 , vital:35607 , https://doi.org/10.3377/004.044.0109
- Description: As a result of numerous introductions and translocations of fishes, South Africa has recently been identified as a fish invasion hotspot (Leprieur et al. 2008). In freshwater ecosystems invasion by alien species is considered a leading mechanism driving environmental change (Clavero & Garcia- Berthou 2005; Garcia-Berthou et al. 2005). In South Africa, documented effects of fish invasions include the extirpation of indigenous fishes through predation (Cambray 2003), changes in invertebrate community structure (Lowe et al. 2008) and hybridization (Canonico et al. 2005). As a result, the management of alien species is a high national priority (National Environmental Management: Biodiversity Act 2004). Such management requires an understanding of the biology, ecology and establishment success of fishes outside their native range.
- Full Text:
- Date Issued: 2009
Shark fishing effort and catch of the ragged-tooth shark Carcharias taurus in the South African competitive shore-angling fishery
- Dicken, Matthew L, Booth, Anthony J, Smale, Malcolm J
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126944 , vital:35937 , https://doi.10.2989/18142320609504209
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126944 , vital:35937 , https://doi.10.2989/18142320609504209
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
Spatial patterns in the biology of the chokka squid, Loligo reynaudii on the Agulhas Bank, South Africa
- Olyott, L J H, Sauer, Warwick H H, Booth, Anthony J
- Authors: Olyott, L J H , Sauer, Warwick H H , Booth, Anthony J
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127053 , vital:35947 , https://doi.10.1007/s11160-006-9027-5
- Description: Although migration patterns for various life history stages of the chokka squid (Loligo reynaudii) have been previously presented, there has been limited comparison of spatial variation in biological parameters. Based on data from research surveys; size ranges of juveniles, subadults and adults on the Agulhas Bank were estimated and presented spatially. The bulk of the results appear to largely support the current acceptance of the life cycle with an annual pattern of squid hatching in the east, migrating westwards to offshore feeding grounds on the Central and Western Agulhas Bank and the west coast and subsequent return migration to the eastern inshore areas to spawn. The number of adult animals in deeper water, particularly in autumn in the central study area probably represents squid spawning in deeper waters and over a greater area than is currently targeted by the fishery. The distribution of life history stages and different feeding areas does not rule out the possibility that discrete populations of L. reynaudii with different biological characteristics inhabit the western and eastern regions of the Agulhas Bank. In this hypothesis, some mixing of the populations does occur but generally squid from the western Agulhas Bank may occur in smaller numbers, grow more slowly and mature at a larger size. Spawning occurs on the western portion of the Agulhas Bank, and juveniles grow and mature on the west coast and the central Agulhas Bank. Future research requirements include the elucidation of the age structure of chokka squid both spatially and temporally, and a comparison of the statolith chemistry and genetic characterization between adults from different spawning areas across the Agulhas Bank.
- Full Text:
- Date Issued: 2007
- Authors: Olyott, L J H , Sauer, Warwick H H , Booth, Anthony J
- Date: 2007
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127053 , vital:35947 , https://doi.10.1007/s11160-006-9027-5
- Description: Although migration patterns for various life history stages of the chokka squid (Loligo reynaudii) have been previously presented, there has been limited comparison of spatial variation in biological parameters. Based on data from research surveys; size ranges of juveniles, subadults and adults on the Agulhas Bank were estimated and presented spatially. The bulk of the results appear to largely support the current acceptance of the life cycle with an annual pattern of squid hatching in the east, migrating westwards to offshore feeding grounds on the Central and Western Agulhas Bank and the west coast and subsequent return migration to the eastern inshore areas to spawn. The number of adult animals in deeper water, particularly in autumn in the central study area probably represents squid spawning in deeper waters and over a greater area than is currently targeted by the fishery. The distribution of life history stages and different feeding areas does not rule out the possibility that discrete populations of L. reynaudii with different biological characteristics inhabit the western and eastern regions of the Agulhas Bank. In this hypothesis, some mixing of the populations does occur but generally squid from the western Agulhas Bank may occur in smaller numbers, grow more slowly and mature at a larger size. Spawning occurs on the western portion of the Agulhas Bank, and juveniles grow and mature on the west coast and the central Agulhas Bank. Future research requirements include the elucidation of the age structure of chokka squid both spatially and temporally, and a comparison of the statolith chemistry and genetic characterization between adults from different spawning areas across the Agulhas Bank.
- Full Text:
- Date Issued: 2007
Should I stay or should I go?: Intra-population variability in movement behaviour of wide-ranging and resident coastal fishes
- Maggs, Jade Q, Cowley, Paul D, Porter, S N, Childs, Amber-Robyn
- Authors: Maggs, Jade Q , Cowley, Paul D , Porter, S N , Childs, Amber-Robyn
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158290 , vital:40170 , https://doi.org/10.3354/meps12953
- Description: Life-cycle diversity is the existence of alternative strategies among coexisting individuals within the same population and is an important factor in the structuring and connectivity of fish stocks. Mark-recapture data, collected along the coastline of southern Africa from 1984-2015, were used to investigate the occurrence of different movement behaviours (resident vs. wide-ranging) in 5 fishery species with contrasting life histories. A total of 88245 individuals was tagged, with recapture rates ranging from 4-27% for the 5 species. Individuals were considered resident if recaptured within 0-5 km of the release site after 365 d at liberty or wide-ranging if recaptured more than 50 km from the release site within 365 d.
- Full Text:
- Date Issued: 2019
- Authors: Maggs, Jade Q , Cowley, Paul D , Porter, S N , Childs, Amber-Robyn
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/158290 , vital:40170 , https://doi.org/10.3354/meps12953
- Description: Life-cycle diversity is the existence of alternative strategies among coexisting individuals within the same population and is an important factor in the structuring and connectivity of fish stocks. Mark-recapture data, collected along the coastline of southern Africa from 1984-2015, were used to investigate the occurrence of different movement behaviours (resident vs. wide-ranging) in 5 fishery species with contrasting life histories. A total of 88245 individuals was tagged, with recapture rates ranging from 4-27% for the 5 species. Individuals were considered resident if recaptured within 0-5 km of the release site after 365 d at liberty or wide-ranging if recaptured more than 50 km from the release site within 365 d.
- Full Text:
- Date Issued: 2019
Understanding the medicines information-seeking behaviour and information needs of South African long-term patients with limited literacy skills:
- Patel, Sonal, Dowse, Roslind
- Authors: Patel, Sonal , Dowse, Roslind
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156676 , vital:40037 , doi: 10.1111/hex.12131
- Description: Although much health information‐seeking behaviour (HISB) research has been reported in patients with good literacy skills, little is known about HISB in patients with limited literacy skills served by under‐resourced health‐care systems. To investigate medicine information‐seeking behaviour and information needs in patients with limited literacy.
- Full Text:
- Date Issued: 2013
- Authors: Patel, Sonal , Dowse, Roslind
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/156676 , vital:40037 , doi: 10.1111/hex.12131
- Description: Although much health information‐seeking behaviour (HISB) research has been reported in patients with good literacy skills, little is known about HISB in patients with limited literacy skills served by under‐resourced health‐care systems. To investigate medicine information‐seeking behaviour and information needs in patients with limited literacy.
- Full Text:
- Date Issued: 2013
Film production incentives, employment transformation and domestic expenditure in South Africa: visualizing subsidy effectiveness
- Collins, Alan, Ishizaka, Alessio, Snowball, Jeanette D
- Authors: Collins, Alan , Ishizaka, Alessio , Snowball, Jeanette D
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67456 , vital:29094 , https://doi.org/10.1080/10286632.2016.1255206
- Description: Publisher version , In 2004 the South African Department of Trade and Industry (DTI) introduced a Film and Television Production Rebate Programme. In order to qualify for the rebate, certain criteria have to be met including success in job creation and skills development within the industry, alongside a particular focus on the percentage of ‘historically disadvantaged individuals’ employed. This study sets out the issues associated with evaluating success in meeting these various criteria and is, to the best of our knowledge, the first study to apply multi-criteria visualization techniques to inform the evaluation of public subsidy effectiveness. The ‘PROMETHEE’ method is applied and apart from presenting project performance in a visually intuitive manner, the approach helps to clarify patterns of relative success, show where policy objectives are competing, and to identify project exemplars for more efficiently guiding future public support in the sector.
- Full Text: false
- Date Issued: 2016
- Authors: Collins, Alan , Ishizaka, Alessio , Snowball, Jeanette D
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67456 , vital:29094 , https://doi.org/10.1080/10286632.2016.1255206
- Description: Publisher version , In 2004 the South African Department of Trade and Industry (DTI) introduced a Film and Television Production Rebate Programme. In order to qualify for the rebate, certain criteria have to be met including success in job creation and skills development within the industry, alongside a particular focus on the percentage of ‘historically disadvantaged individuals’ employed. This study sets out the issues associated with evaluating success in meeting these various criteria and is, to the best of our knowledge, the first study to apply multi-criteria visualization techniques to inform the evaluation of public subsidy effectiveness. The ‘PROMETHEE’ method is applied and apart from presenting project performance in a visually intuitive manner, the approach helps to clarify patterns of relative success, show where policy objectives are competing, and to identify project exemplars for more efficiently guiding future public support in the sector.
- Full Text: false
- Date Issued: 2016
Is economic impact a good way of justifying the inclusion of foreign students at local universities?
- Snowball, Jeanette D, Antrobus, Geoffrey G
- Authors: Snowball, Jeanette D , Antrobus, Geoffrey G
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67470 , vital:29098 , http://dx.doi.org/10.4314/sajhe.v20i3.25593
- Description: Pre-print , In the debate surrounding the costs and benefits of having foreign students at South African universities, the financial contributions of foreign students to their host economies is sometimes cited. This article reports the results of a comparison between the economic impact on the Grahamstown economy of the spending of foreign and local students at Rhodes University. It finds that the spending patterns of both types of students are remarkably similar and that the somewhat higher economic impact of foreign students is largely as a result of their propensity to choose the more expensive residence accommodation, rather than as a result of greater average spending generally. We suggest that economic impact studies should be used with caution when making the case for continued public subsidy of goods with significant non-market values and that opportunity costs should also be considered.
- Full Text:
- Date Issued: 2006
Is economic impact a good way of justifying the inclusion of foreign students at local universities?
- Authors: Snowball, Jeanette D , Antrobus, Geoffrey G
- Date: 2006
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67470 , vital:29098 , http://dx.doi.org/10.4314/sajhe.v20i3.25593
- Description: Pre-print , In the debate surrounding the costs and benefits of having foreign students at South African universities, the financial contributions of foreign students to their host economies is sometimes cited. This article reports the results of a comparison between the economic impact on the Grahamstown economy of the spending of foreign and local students at Rhodes University. It finds that the spending patterns of both types of students are remarkably similar and that the somewhat higher economic impact of foreign students is largely as a result of their propensity to choose the more expensive residence accommodation, rather than as a result of greater average spending generally. We suggest that economic impact studies should be used with caution when making the case for continued public subsidy of goods with significant non-market values and that opportunity costs should also be considered.
- Full Text:
- Date Issued: 2006
Where angels fear to tread: online peer-assessment in a large first-year class
- Mostert, Markus, Snowball, Jeanette D
- Authors: Mostert, Markus , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68845 , vital:29330 , https://doi.org/10.1080/02602938.2012.683770
- Description: Publisher version , In the context of widening participation, large classes and increased diversity, assessment of student learning is becoming increasingly problematic in that providing formative feedback aimed at developing student writing proves to be particularly laborious. Although the potential value of peer assessment has been well documented in the literature, the associated administrative burden, also in relation to managing anonymity and intellectual ownership, makes this option less attractive, particularly in large classes. A potential solution involves the use of information and communication technologies to automate the logistics associated with peer assessment in a time-efficient way. However, uptake of such systems in the higher education community is limited, and research in this area is only beginning. This case study reports on the use of the Moodle Workshop module for formative peer assessment of students’ individual work in a first-year introductory macro-economics class of over 800 students. Data were collected through an end-of-course evaluation survey of students. The study found that using the feature-rich Workshop module not only addressed many of the practical challenges associated with paper-based peer assessments, but also provided a range of additional options for enhancing validity and reliability of peer assessments that would not be possible with paper-based systems.
- Full Text: false
- Date Issued: 2013
- Authors: Mostert, Markus , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68845 , vital:29330 , https://doi.org/10.1080/02602938.2012.683770
- Description: Publisher version , In the context of widening participation, large classes and increased diversity, assessment of student learning is becoming increasingly problematic in that providing formative feedback aimed at developing student writing proves to be particularly laborious. Although the potential value of peer assessment has been well documented in the literature, the associated administrative burden, also in relation to managing anonymity and intellectual ownership, makes this option less attractive, particularly in large classes. A potential solution involves the use of information and communication technologies to automate the logistics associated with peer assessment in a time-efficient way. However, uptake of such systems in the higher education community is limited, and research in this area is only beginning. This case study reports on the use of the Moodle Workshop module for formative peer assessment of students’ individual work in a first-year introductory macro-economics class of over 800 students. Data were collected through an end-of-course evaluation survey of students. The study found that using the feature-rich Workshop module not only addressed many of the practical challenges associated with paper-based peer assessments, but also provided a range of additional options for enhancing validity and reliability of peer assessments that would not be possible with paper-based systems.
- Full Text: false
- Date Issued: 2013
Dancing with the devil: formative peer assessment and academic performance
- Mostert, Markus, Snowball, Jeanette D
- Authors: Mostert, Markus , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69301 , vital:29483 , https://doi.org/10.1080/07294360.2012.705262
- Description: Peer assessment can be important in developing active and independent learners, as well as providing more and faster feedback in large classes, compared to marking done by tutors. In addition, the evaluative, critical stance required by students in order to assess their peers' work encourages the development of higher-order cognitive skills. Changing roles from being assessed to being an assessor can also improve students' ability to judge and improve on their own work. However, peer assessment does have potential problems and there is some debate as to the appropriate academic level at which to implement it, the kinds of feedback that are given and the ways in which students respond. In addition, there is little evidence that peer assessment has an impact on academic performance. This research reports the results of an online peer assessment exercise for a macroeconomics essay conducted in a large Economics 1 class at Rhodes University. Of the 800 students, about half participated in the peer assessment exercise. Data were collected from students via a formal course evaluation. In addition, a sample of 50 essays was evaluated in terms of the relationship between peer marks and final (tutor) marks received and the impact that peer assessment had on the quality of the final essay submitted. An Ordinary Least Squares regression was used to investigate the impact of peer assessment participation on marks. Results showed that peer marks tended to ‘bunch’ in the 60–68% range, indicating the reluctance of peers to give very high or low marks. In general, peers gave more useful feedback on technical aspects, such as presentation and referencing (which were also the categories in which students most often made improvements), than on content. Regression analysis showed that peer assessment participation was not a significant determinant of final essay mark, but that economics ability and English language proficiency were.
- Full Text: false
- Date Issued: 2013
- Authors: Mostert, Markus , Snowball, Jeanette D
- Date: 2013
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69301 , vital:29483 , https://doi.org/10.1080/07294360.2012.705262
- Description: Peer assessment can be important in developing active and independent learners, as well as providing more and faster feedback in large classes, compared to marking done by tutors. In addition, the evaluative, critical stance required by students in order to assess their peers' work encourages the development of higher-order cognitive skills. Changing roles from being assessed to being an assessor can also improve students' ability to judge and improve on their own work. However, peer assessment does have potential problems and there is some debate as to the appropriate academic level at which to implement it, the kinds of feedback that are given and the ways in which students respond. In addition, there is little evidence that peer assessment has an impact on academic performance. This research reports the results of an online peer assessment exercise for a macroeconomics essay conducted in a large Economics 1 class at Rhodes University. Of the 800 students, about half participated in the peer assessment exercise. Data were collected from students via a formal course evaluation. In addition, a sample of 50 essays was evaluated in terms of the relationship between peer marks and final (tutor) marks received and the impact that peer assessment had on the quality of the final essay submitted. An Ordinary Least Squares regression was used to investigate the impact of peer assessment participation on marks. Results showed that peer marks tended to ‘bunch’ in the 60–68% range, indicating the reluctance of peers to give very high or low marks. In general, peers gave more useful feedback on technical aspects, such as presentation and referencing (which were also the categories in which students most often made improvements), than on content. Regression analysis showed that peer assessment participation was not a significant determinant of final essay mark, but that economics ability and English language proficiency were.
- Full Text: false
- Date Issued: 2013
Introducing a learning management system in a large first year class: impact on lecturers and students
- Snowball, Jeanette D, Mostert, Markus
- Authors: Snowball, Jeanette D , Mostert, Markus
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68631 , vital:29297 , https://hdl.handle.net/10520/EJC37639
- Description: Publisher version , The challenges of teaching large classes are well documented in the literature on teaching in higher education. Information and communication technologies (ICTs) have the potential to address some of these challenges, but, used inappropriately, technology can perpetuate entrenched practices and simply support performance models of teaching that encourage transmission approaches to learning. This article reports on the impact of implementing a learning management system (LMS) in a first year introductory macroeconomics course with 600 students in a blended learning context. Experiences of the course coordinator, lecturers and an educational technologist are discussed and data was also collected on student perceptions via a course evaluation questionnaire. Results show that the LMS was successful in a number of areas, particularly in improving the lecturers' accessibility to students and in encouraging interaction and participations in online discussion forums.
- Full Text: false
- Date Issued: 2010
- Authors: Snowball, Jeanette D , Mostert, Markus
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68631 , vital:29297 , https://hdl.handle.net/10520/EJC37639
- Description: Publisher version , The challenges of teaching large classes are well documented in the literature on teaching in higher education. Information and communication technologies (ICTs) have the potential to address some of these challenges, but, used inappropriately, technology can perpetuate entrenched practices and simply support performance models of teaching that encourage transmission approaches to learning. This article reports on the impact of implementing a learning management system (LMS) in a first year introductory macroeconomics course with 600 students in a blended learning context. Experiences of the course coordinator, lecturers and an educational technologist are discussed and data was also collected on student perceptions via a course evaluation questionnaire. Results show that the LMS was successful in a number of areas, particularly in improving the lecturers' accessibility to students and in encouraging interaction and participations in online discussion forums.
- Full Text: false
- Date Issued: 2010
Exploring intermolecular contacts in multi-substituted benzaldehyde derivatives: X-ray, Hirshfeld surface and lattice energy analyses
- Hulushe, Siya T, Manyeruke, Meloddy H, Louzada, Marcel, Rigin, Sergei, Hosten, Eric C, Watkins, Gareth M
- Authors: Hulushe, Siya T , Manyeruke, Meloddy H , Louzada, Marcel , Rigin, Sergei , Hosten, Eric C , Watkins, Gareth M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148483 , vital:38743 , DOI: 10.1039/C9RA10752E
- Description: Crystal structures of six benzaldehyde derivatives (1–6) have been determined and their supramolecular networks were established by an X-ray crystallographic study. The study has shown that the compounds are linked by various intermolecular interactions such as weak C–H⋯O hydrogen bonding, and C–H⋯π, π–π and halogen bonding interactions which consolidate and strengthen the formation of these molecular assemblies. The carbonyl group generates diverse synthons in 1–6 via intermolecular C–H⋯O hydrogen bonds. An interplay of C–H⋯O hydrogen bonds, and C–H⋯π and π–π stacking interactions facilitates the formation of multi-dimensional supramolecular networks. Crystal packings in 4 and 5 are further generated by type I halogen⋯halogen bonding interactions. The differences in crystal packing are represented by variation of substitution positions in the compounds. Structure 3 is isomorphous with 4 but there are subtle differences in their crystal packing.
- Full Text:
- Date Issued: 2020
- Authors: Hulushe, Siya T , Manyeruke, Meloddy H , Louzada, Marcel , Rigin, Sergei , Hosten, Eric C , Watkins, Gareth M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148483 , vital:38743 , DOI: 10.1039/C9RA10752E
- Description: Crystal structures of six benzaldehyde derivatives (1–6) have been determined and their supramolecular networks were established by an X-ray crystallographic study. The study has shown that the compounds are linked by various intermolecular interactions such as weak C–H⋯O hydrogen bonding, and C–H⋯π, π–π and halogen bonding interactions which consolidate and strengthen the formation of these molecular assemblies. The carbonyl group generates diverse synthons in 1–6 via intermolecular C–H⋯O hydrogen bonds. An interplay of C–H⋯O hydrogen bonds, and C–H⋯π and π–π stacking interactions facilitates the formation of multi-dimensional supramolecular networks. Crystal packings in 4 and 5 are further generated by type I halogen⋯halogen bonding interactions. The differences in crystal packing are represented by variation of substitution positions in the compounds. Structure 3 is isomorphous with 4 but there are subtle differences in their crystal packing.
- Full Text:
- Date Issued: 2020
Teacher education in post-apartheid South Africa: navigating a way through competing state and global imperatives for change
- Schäfer, Marc, Wilmot, P Dianne
- Authors: Schäfer, Marc , Wilmot, P Dianne
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140905 , vital:37928 , DOI: 10.1007/s11125-012-9220-3
- Description: This article focuses on teacher education in post-apartheid South Africa. It argues that the restructuring and reorganization of teacher education is at the nexus of the axes of tension created by national and global imperatives for change. Along with the dismantling of apartheid and the transition to a free and democratic state in 1994 came the urgent need for social reconstruction, democratization, redress, social justice, and equity. At the same time, and as part of a global context, the country needed global competitiveness, human capital development, global skills, international standards, and accountability. These competing modernist discourses have informed the design and orientation of the National Qualifications Framework and national curriculum that took place in parallel with, and simultaneous to, the restructuring and reform of teacher education. This article reviews literature pertinent to understanding the post-apartheid transformation in South African education in general and teacher education in particular. It concludes that policy makers have managed to navigate a way through the axis of tension created by opposed orientations to transformation. A more equitable and improved system of teacher education has been achieved but critical issues of teacher quality and quantity have emerged which urgently need resolution.
- Full Text:
- Date Issued: 2012
- Authors: Schäfer, Marc , Wilmot, P Dianne
- Date: 2012
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140905 , vital:37928 , DOI: 10.1007/s11125-012-9220-3
- Description: This article focuses on teacher education in post-apartheid South Africa. It argues that the restructuring and reorganization of teacher education is at the nexus of the axes of tension created by national and global imperatives for change. Along with the dismantling of apartheid and the transition to a free and democratic state in 1994 came the urgent need for social reconstruction, democratization, redress, social justice, and equity. At the same time, and as part of a global context, the country needed global competitiveness, human capital development, global skills, international standards, and accountability. These competing modernist discourses have informed the design and orientation of the National Qualifications Framework and national curriculum that took place in parallel with, and simultaneous to, the restructuring and reform of teacher education. This article reviews literature pertinent to understanding the post-apartheid transformation in South African education in general and teacher education in particular. It concludes that policy makers have managed to navigate a way through the axis of tension created by opposed orientations to transformation. A more equitable and improved system of teacher education has been achieved but critical issues of teacher quality and quantity have emerged which urgently need resolution.
- Full Text:
- Date Issued: 2012
Potential Gaps during the Transition from the Embodied through Symbolic to Formal Worlds of Reflective Symmetry:
- Mhlolo, Michael K, Schäfer, Marc
- Authors: Mhlolo, Michael K , Schäfer, Marc
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141117 , vital:37945 , https://doi.org/10.1080/10288457.2014.925269
- Description: Even though reflective symmetry is heavily embedded in the everyday, learners continue to experience challenges when they mathematize concepts from this informal/everyday context. In this article we argue that symmetry exists in nature, it can also be symbolized algebraically and it can be abstracted into the world of axioms and theorems. We problematize this multiple nature of symmetry which on one hand is supportive and on the other acts as a contributory factor to learners' gaps in knowledge. Tall's three worlds of mathematics helped us to show the transition of symmetry from the embodied through symbolic to the formal world and the inherent gaps attributed to the shifts in thinking thereof. We then used this same framework to analyse learners' responses to a reflective symmetry task. The results show that many learner responses could be explained explicitly by the lack of flexibility in the applicability of experiences in the embodied world of reflective symmetry.
- Full Text:
- Date Issued: 2014
- Authors: Mhlolo, Michael K , Schäfer, Marc
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141117 , vital:37945 , https://doi.org/10.1080/10288457.2014.925269
- Description: Even though reflective symmetry is heavily embedded in the everyday, learners continue to experience challenges when they mathematize concepts from this informal/everyday context. In this article we argue that symmetry exists in nature, it can also be symbolized algebraically and it can be abstracted into the world of axioms and theorems. We problematize this multiple nature of symmetry which on one hand is supportive and on the other acts as a contributory factor to learners' gaps in knowledge. Tall's three worlds of mathematics helped us to show the transition of symmetry from the embodied through symbolic to the formal world and the inherent gaps attributed to the shifts in thinking thereof. We then used this same framework to analyse learners' responses to a reflective symmetry task. The results show that many learner responses could be explained explicitly by the lack of flexibility in the applicability of experiences in the embodied world of reflective symmetry.
- Full Text:
- Date Issued: 2014