Academic literacy in management education
- Pearse, Noel J, Amos, Trevor L
- Authors: Pearse, Noel J , Amos, Trevor L
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270065 , vital:54392 , xlink:href="https://hdl.handle.net/10520/EJC36783"
- Description: Although management education aims to equip students with relevant knowledge, skills and competencies, making explicit and developing the cognitive thought processes necessary for management students to deal effectively with the current and future demands of the world of work, have been neglected. This article argues for the development of "complicated understanding" (Bartunek, Gordon and Weathersby 1983) in management students, through cultivating academic literacy. Using mediation, reflective inquiry and reflective writing interactively, it is illustrated how academic literacy could be promoted at the post-graduate level.
- Full Text:
- Date Issued: 2000
- Authors: Pearse, Noel J , Amos, Trevor L
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/270065 , vital:54392 , xlink:href="https://hdl.handle.net/10520/EJC36783"
- Description: Although management education aims to equip students with relevant knowledge, skills and competencies, making explicit and developing the cognitive thought processes necessary for management students to deal effectively with the current and future demands of the world of work, have been neglected. This article argues for the development of "complicated understanding" (Bartunek, Gordon and Weathersby 1983) in management students, through cultivating academic literacy. Using mediation, reflective inquiry and reflective writing interactively, it is illustrated how academic literacy could be promoted at the post-graduate level.
- Full Text:
- Date Issued: 2000
An investigation into the neuroprotective properties of ibuprofen
- Lambat, Zaynab Y, Conrad, Natasha, Anoopkumar-Dukie, Shailendra, Walker, Roderick B, Daya, Santylal
- Authors: Lambat, Zaynab Y , Conrad, Natasha , Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184335 , vital:44209 , xlink:href="https://doi.org/10.1023/A:1011115006856"
- Description: There is increasing evidence suggesting a protective role for anti-inflammatory medications in neurological disorders such as Alzheimer's disease (AD). While there has not been any direct evidence for this, a number of clinical studies indicate that those patients who have had a history of nonsteroidal anti-inflammatory use, have a lower incidence of AD. Since there is currently no evidence on the mechanism by which these agents offer possible neuroprotection, we investigated the potential neuroprotective properties of the nonsteroidal anti-inflammatory drug, ibuprofen, by examining whether this agent could reduce lipid peroxidation and superoxide radical generation. Quinolinic acid and cyanide, known neurotoxins, were used to induce lipid peroxidation and superoxide anion formation respectively, in rat brain homogenate. The results show that ibuprofen significantly (p more than 0.05) reduced quinolinic acid-induced lipid peroxidation and cyanide-induced superoxide production. The results of the present report therefore suggest a possible mechanism for the neuroprotective effect of ibuprofen.
- Full Text: false
- Date Issued: 2000
- Authors: Lambat, Zaynab Y , Conrad, Natasha , Anoopkumar-Dukie, Shailendra , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184335 , vital:44209 , xlink:href="https://doi.org/10.1023/A:1011115006856"
- Description: There is increasing evidence suggesting a protective role for anti-inflammatory medications in neurological disorders such as Alzheimer's disease (AD). While there has not been any direct evidence for this, a number of clinical studies indicate that those patients who have had a history of nonsteroidal anti-inflammatory use, have a lower incidence of AD. Since there is currently no evidence on the mechanism by which these agents offer possible neuroprotection, we investigated the potential neuroprotective properties of the nonsteroidal anti-inflammatory drug, ibuprofen, by examining whether this agent could reduce lipid peroxidation and superoxide radical generation. Quinolinic acid and cyanide, known neurotoxins, were used to induce lipid peroxidation and superoxide anion formation respectively, in rat brain homogenate. The results show that ibuprofen significantly (p more than 0.05) reduced quinolinic acid-induced lipid peroxidation and cyanide-induced superoxide production. The results of the present report therefore suggest a possible mechanism for the neuroprotective effect of ibuprofen.
- Full Text: false
- Date Issued: 2000
Comparative Spectroscopic and Electrochemical Properties of Bis (octakis (dodecylthio) naphthalocyaninato) europium (III) and Bis (tetra-tert-butylnaphthalocyaninato) europium (III) Complexes
- Nyokong, Tebello, Furuya, Fumio, Kobayashi, Nagao, Du, Daming, Liu, Wei, Jiang, Jianzhuang
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000
- Authors: Nyokong, Tebello , Furuya, Fumio , Kobayashi, Nagao , Du, Daming , Liu, Wei , Jiang, Jianzhuang
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293174 , vital:57062 , xlink:href="https://doi.org/10.1021/ic990483b"
- Description: Bis(substituted-2,3-naphthalocyaninato)europium(III) complexes: bis(octakis(dodecylthio)-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(SC12H25)8]2, 1} and bis(tetra-tert-butyl-2,3-naphthalocyaninato)europium(III) {Eu[2,3-Nc(t-Bu)4]2, 2} have been synthesized by cyclic tetramerization of naphthalonitriles with Eu(acac)3·H2O in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in refluxing n-octanol. These compounds were characterized by UV−visible, magnetic circular dichroism (MCD), near-IR, IR, EPR, and mass spectroscopies. The absorption and MCD spectra of 1 showed splitting of the Q band, with peaks at 700 and 784 nm, red shifted from the Q band of 2 at 763 nm. The absorption and MCD spectral band deconvolution calculations of complex 1 gave two A terms in the Q-band region. The A terms are assigned to 2A2 → 2E1 transitions. Cyclic voltammograms of 1 and 2 showed reversible oxidation couples at E1/2 = −0.28 V (for 2) and −0.25 V (for 1) vs ferrocenium/ferrocene (Fc+/Fc). The second oxidation exhibited a complicated behavior for both complexes. The reduction couples for 2 were observed at E1/2 = −0.61, −1.64, −1.97, and −2.42 V, and for 1 they were observed at E1/2 = −0.62, −1.60, −1.86, and −2.27 V vs Fc+/Fc. Spectral changes observed on chemical oxidation and reduction of the complexes are presented, and the behaviors of 1 and 2 are compared.
- Full Text:
- Date Issued: 2000
Comparison of plant diversity in protected and communal lands in the Bushbuckridge lowveld savanna, South Africa
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181885 , vital:43777 , xlink:href="https://doi.org/10.1016/S0006-3207(00)00001-X"
- Description: Patterns of higher plant species richness and beta diversity were assessed using standard Modified-Whittaker plots in relation to land use, slope position and mean annual rainfall across a rainfall gradient in the savanna areas of the Bushbuckridge lowveld, South Africa. In particular, comparison of communal areas with adjacent protected areas was important in showing the impacts of potential changes in land use within an overarching catchment management plan. Although most of the protected areas considered preservation of biodiversity as their primary goal, they were characterised by significantly fewer plant species than the adjacent, highly utilised, communal lands, at both the plot and point scale. Slope position also had a significant effect on plant species richness, with eutrophic bottomlands having c. 30% more species than the dystrophic toplands. This adds weight to the need for greater public awareness for the judicious use and management of the sensitive bottomlands, which fringe the primary drainage lines that are vital for sustained supplies of good quality surface water in this semi-arid environment. The total number of species increased with increasing mean annual rainfall across the rainfall gradient. This suggests that, if the catchment management plan aims to identify additional areas for conservation, the higher rainfall areas should be the first to be assessed. Species turnover was greater along the rainfall gradient than the catenal gradient between toplands and bottomlands.
- Full Text:
- Date Issued: 2000
- Authors: Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181885 , vital:43777 , xlink:href="https://doi.org/10.1016/S0006-3207(00)00001-X"
- Description: Patterns of higher plant species richness and beta diversity were assessed using standard Modified-Whittaker plots in relation to land use, slope position and mean annual rainfall across a rainfall gradient in the savanna areas of the Bushbuckridge lowveld, South Africa. In particular, comparison of communal areas with adjacent protected areas was important in showing the impacts of potential changes in land use within an overarching catchment management plan. Although most of the protected areas considered preservation of biodiversity as their primary goal, they were characterised by significantly fewer plant species than the adjacent, highly utilised, communal lands, at both the plot and point scale. Slope position also had a significant effect on plant species richness, with eutrophic bottomlands having c. 30% more species than the dystrophic toplands. This adds weight to the need for greater public awareness for the judicious use and management of the sensitive bottomlands, which fringe the primary drainage lines that are vital for sustained supplies of good quality surface water in this semi-arid environment. The total number of species increased with increasing mean annual rainfall across the rainfall gradient. This suggests that, if the catchment management plan aims to identify additional areas for conservation, the higher rainfall areas should be the first to be assessed. Species turnover was greater along the rainfall gradient than the catenal gradient between toplands and bottomlands.
- Full Text:
- Date Issued: 2000
Cyanide-induced free radical production and lipid peroxidation in rat brain homogenate is reduced by aspirin
- Daya, Santylal, Walker, Roderick B, Anoopkumar-Dukie, Shailendra
- Authors: Daya, Santylal , Walker, Roderick B , Anoopkumar-Dukie, Shailendra
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184346 , vital:44210 , xlink:href="https://doi.org/10.1007/BF02674529"
- Description: The neuroprotective properties of aspirin were investigated using cyanide-induced neurotoxicity as model. Cyanide, a known neurotoxic agent significantly increased lipid peroxidation and superoxide anion levels in rat brain homogenate in a concentration-dependent manner (0.25–1.0 mM). When homogenate, containing 1.0 mM KCN was cotreated with aspirin (1.0 mM) there was a significant decrease in lipid peroxidation. Aspirin (0.5 mM and 1.0 mM) also significantly reduced KCN-induced superoxide anion generation. The results of the present report therefore indicate a neuroprotective role for aspirin.
- Full Text:
- Date Issued: 2000
- Authors: Daya, Santylal , Walker, Roderick B , Anoopkumar-Dukie, Shailendra
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184346 , vital:44210 , xlink:href="https://doi.org/10.1007/BF02674529"
- Description: The neuroprotective properties of aspirin were investigated using cyanide-induced neurotoxicity as model. Cyanide, a known neurotoxic agent significantly increased lipid peroxidation and superoxide anion levels in rat brain homogenate in a concentration-dependent manner (0.25–1.0 mM). When homogenate, containing 1.0 mM KCN was cotreated with aspirin (1.0 mM) there was a significant decrease in lipid peroxidation. Aspirin (0.5 mM and 1.0 mM) also significantly reduced KCN-induced superoxide anion generation. The results of the present report therefore indicate a neuroprotective role for aspirin.
- Full Text:
- Date Issued: 2000
Direct use values of secondary resources harvested from communal savannas in the Bushbuckridge lowveld, South Africa
- Shackleton, Charlie M, Shackleton, Sheona E
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182798 , vital:43875 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20000614194"
- Description: This study reports on the direct use value of secondary resources harvested by rural communities in a savanna region of South Africa. Data pertaining to the use, amount and direct use value of 11 secondary resources were presented individually, along with a final composite value. Only five resources (fuelwood, construction wood, edible fruits, edible herbs, and medicinal plants), individually accounted for more than 10% of the total value per hectare (US$ 141), and together they represented over 94% of the total value per hectare. On a per household basis, only 3 of the 11 resources contributed 10% or more to the total direct use value (US$ 386 used at home and US$ 767 traded), and together contributed greater than 71% of the total direct use value per household. Two-thirds of the value per household was traded locally with other households or regionally, rather than consumed at home. The total value per hectare compared favourably with other land uses within the region, except for capital intensive enterprises. The returns to collecting and selling secondary resources were higher than those paid for local agricultural wage labour. The extraction rates of several of the secondary resources are probably sustainable but not for the more important ones such as fuelwood, construction wood and medicinal plants.
- Full Text:
- Date Issued: 2000
- Authors: Shackleton, Charlie M , Shackleton, Sheona E
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182798 , vital:43875 , xlink:href="https://www.cabdirect.org/cabdirect/abstract/20000614194"
- Description: This study reports on the direct use value of secondary resources harvested by rural communities in a savanna region of South Africa. Data pertaining to the use, amount and direct use value of 11 secondary resources were presented individually, along with a final composite value. Only five resources (fuelwood, construction wood, edible fruits, edible herbs, and medicinal plants), individually accounted for more than 10% of the total value per hectare (US$ 141), and together they represented over 94% of the total value per hectare. On a per household basis, only 3 of the 11 resources contributed 10% or more to the total direct use value (US$ 386 used at home and US$ 767 traded), and together contributed greater than 71% of the total direct use value per household. Two-thirds of the value per household was traded locally with other households or regionally, rather than consumed at home. The total value per hectare compared favourably with other land uses within the region, except for capital intensive enterprises. The returns to collecting and selling secondary resources were higher than those paid for local agricultural wage labour. The extraction rates of several of the secondary resources are probably sustainable but not for the more important ones such as fuelwood, construction wood and medicinal plants.
- Full Text:
- Date Issued: 2000
Electrocatalytic behavior of substituted cobalt phthalocyanines towards the oxidation of cysteine
- Maree, Suzanne, Nyokong, Tebello
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293268 , vital:57070 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293268 , vital:57070 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
Electrocatalytic behavior of substituted cobalt phthalocyanines towards the oxidation of cysteine
- Maree, Suzanne, Nyokong, Tebello
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293185 , vital:57063 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
- Authors: Maree, Suzanne , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293185 , vital:57063 , xlink:href="https://doi.org/10.1016/S0022-0728(00)00281-3"
- Description: Ring substituted cobalt phthalocyanine complexes of the form CoPc(X)4, (where X=NH2, NO2, C(CH3)3, SO3H and COOH) are compared for their catalytic activities towards the oxidation of cysteine. The potential for the electrocatalytic oxidation of cysteine is closely related to the CoIII/CoII couple of the CoPc(X)4 complexes in acidic media and to the CoII/CoI couple in basic media. The catalytic currents and the oxidation potential for cysteine are dependent on the pH of the solution, the potential becoming less positive as the pH increases and the catalytic currents decreasing with increase in pH, for the same concentration of cysteine. The magnitudes of the catalytic currents (after ten scans) for cysteine oxidation at pH 8.3 and on electrodes modified with the CoPc(X)4 complexes increased with the nature of the ring substituent as follows: NO2 less than NH2 less than SO3H less than C(CH3)3 less than COOH.
- Full Text:
- Date Issued: 2000
Electrocatalytic properties of vitamin B12 towards oxidation and reduction of nitric oxide
- Vilakazi, Sibulelo Lea, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo Lea , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293196 , vital:57064 , xlink:href="https://doi.org/10.1016/S0013-4686(00)00628-9"
- Description: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction and oxidation of nitric oxide. When VB12 is adsorbed on glassy carbon electrodes, it catalyses the reduction of nitric oxide (NO) in pH 4 and 9 buffers. In the absence of NO, cyclic voltammetry shows that VB12 is reduced by a one-step two-electron reduction from CoIII to the CoI species. Addition of NO at pH 9 to solutions of VB12 resulted in the splitting of the cyclic voltammetry peaks as a result of a consecutive one-electron reduction of the central CoIII metal in VB12 to CoII and finally to CoI. The catalytic peak for oxidation of NO on a glassy carbon electrode modified with VB12 was observed at 1.21 V versus Ag∣AgCl, at pH 9. The products of the catalytic reduction of nitric oxide include ammonia and hydroxylamine.
- Full Text:
- Date Issued: 2000
- Authors: Vilakazi, Sibulelo Lea , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293196 , vital:57064 , xlink:href="https://doi.org/10.1016/S0013-4686(00)00628-9"
- Description: This paper reports on the catalytic behaviour of cyanocobalamin (VB12) towards the reduction and oxidation of nitric oxide. When VB12 is adsorbed on glassy carbon electrodes, it catalyses the reduction of nitric oxide (NO) in pH 4 and 9 buffers. In the absence of NO, cyclic voltammetry shows that VB12 is reduced by a one-step two-electron reduction from CoIII to the CoI species. Addition of NO at pH 9 to solutions of VB12 resulted in the splitting of the cyclic voltammetry peaks as a result of a consecutive one-electron reduction of the central CoIII metal in VB12 to CoII and finally to CoI. The catalytic peak for oxidation of NO on a glassy carbon electrode modified with VB12 was observed at 1.21 V versus Ag∣AgCl, at pH 9. The products of the catalytic reduction of nitric oxide include ammonia and hydroxylamine.
- Full Text:
- Date Issued: 2000
From virtual to physical reality with paper folding
- Authors: Bangay, Shaun D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432669 , vital:72891 , https://doi.org/10.1016/S0925-7721(99)00048-6
- Description: Objects in a virtual world can be converted into hardcopy by per-pendicular projection of each face onto a sheet of paper, cutting and gluing. Previously, use of this technique was restricted to a limited class of polyhedral objects. This paper extends this process to realis-tic virtual objects, with the traditional origami restriction of using only a single sheet of paper. A number of algorithms are explored to achieve this goal. The use of heuristics allows solutions to be found without exhaustive search of all possible layouts. Approaches to deal with pathological cases are described. The techniques have al-ready been successfully applied to a number of complex models, selected from a number of model archives on the Internet.
- Full Text:
- Date Issued: 2000
- Authors: Bangay, Shaun D
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432669 , vital:72891 , https://doi.org/10.1016/S0925-7721(99)00048-6
- Description: Objects in a virtual world can be converted into hardcopy by per-pendicular projection of each face onto a sheet of paper, cutting and gluing. Previously, use of this technique was restricted to a limited class of polyhedral objects. This paper extends this process to realis-tic virtual objects, with the traditional origami restriction of using only a single sheet of paper. A number of algorithms are explored to achieve this goal. The use of heuristics allows solutions to be found without exhaustive search of all possible layouts. Approaches to deal with pathological cases are described. The techniques have al-ready been successfully applied to a number of complex models, selected from a number of model archives on the Internet.
- Full Text:
- Date Issued: 2000
Histological validation of gonadal macroscopic staging criteria for Labeo cylindricus (Pisces: Cyprinidae).
- Booth, Anthony J, Weyl, Olaf L F
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446824 , vital:74563 , https://hdl.handle.net/10520/EJC17754
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2000
- Authors: Booth, Anthony J , Weyl, Olaf L F
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446824 , vital:74563 , https://hdl.handle.net/10520/EJC17754
- Description: Histological examination of gametogenesis revealed that the current staging criteria used to assess gonadal recrudescence of the redeye labeo, Labeo cylindricus, were adequate. Gametogenesis was qualitatively similar to that of freshwater teleosts with a clearly defined seasonal reproductive cycle. L. cylindricus undergoes seasonal gross morphological and cytological gonadal changes with previtellogenesis dominating during the winter, vitellogenic development during spring and summer culminating in large-scale spawning at the end of summer. Post-spawning mass atresia of oocytes was evident in autumn. The histological data presented support macroscopical evidence that L. cylindricus is a synchronous iteroparous spawner, reproducing over a short period each year throughout its life-span.
- Full Text:
- Date Issued: 2000
Impact of fire frequency on woody community structure and soil nutrients in the Kruger National Park
- Shackleton, Charlie M, Scholes, Robert J
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181874 , vital:43776 , xlink:href="https://doi.org/10.4102/koedoe.v43i1.210"
- Description: Although fire is recognised as an important determinant of the structure and function of South African savannas, there are few studies of long-term impacts. Controlled burning blocks of contrasting fire season and frequency have been maintained throughout the Kruger National Park for almost 50 years. This paper reports on a quantitative study of the Satara plots to determine the long-term impacts of fire frequency on woody community structure and soil nutrients. Increasing fire frequency significantly decreased woody plant basal area, biomass, density, height, and mean stem circumference. The number of stems per plant and the proportion of regenerative stems increased with increasing fire frequency. Effects on species richness of woody plants were inconsistent. There were no significant differences attributable to fire frequency for any of the soil variables except organic matter and magnesium. Organic carbon was highest in the fire exclusion treatment and lowest in soils from plots burnt triennially. Magnesium levels were greatest in the annually burnt soils and least in the triennial plots.
- Full Text:
- Date Issued: 2000
Impact of fire frequency on woody community structure and soil nutrients in the Kruger National Park
- Authors: Shackleton, Charlie M , Scholes, Robert J
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181874 , vital:43776 , xlink:href="https://doi.org/10.4102/koedoe.v43i1.210"
- Description: Although fire is recognised as an important determinant of the structure and function of South African savannas, there are few studies of long-term impacts. Controlled burning blocks of contrasting fire season and frequency have been maintained throughout the Kruger National Park for almost 50 years. This paper reports on a quantitative study of the Satara plots to determine the long-term impacts of fire frequency on woody community structure and soil nutrients. Increasing fire frequency significantly decreased woody plant basal area, biomass, density, height, and mean stem circumference. The number of stems per plant and the proportion of regenerative stems increased with increasing fire frequency. Effects on species richness of woody plants were inconsistent. There were no significant differences attributable to fire frequency for any of the soil variables except organic matter and magnesium. Organic carbon was highest in the fire exclusion treatment and lowest in soils from plots burnt triennially. Magnesium levels were greatest in the annually burnt soils and least in the triennial plots.
- Full Text:
- Date Issued: 2000
Interaction between iron (II) tetrasulfophthalocyanine and the neurotransmitters, serotonin and dopamine
- Oni, Joshua, Nyokong, Tebello
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293223 , vital:57066 , xlink:href="https://doi.org/10.1016/S0277-5387(00)00421-6"
- Description: This work reports on the kinetics of interaction of iron(II) tetrasulfophthalocyanine, [FeTSPc]4−, with dopamine (DA) and serotonin (5-HT). The interaction results in the coordination of dopamine and serotonin to [FeTSPc]4−, followed by internal electron transfer and the formation of [(DA+)FeITSPc]4− and [(5-HT+) FeITSPc]4− complexes, respectively. The rate constants for the coordination of dopamine or serotonin to [FeTSPc]4− and the formation of the FeITSPc species were found to be kf=6.8 and 9.3 dm3 mol−1 s−1, respectively. The equilibrium constants were 2.2×103 and 1.5×103 dm3 mol−1, respectively, for the interaction of dopamine or serotonin to [FeTSPc]4−.
- Full Text:
- Date Issued: 2000
- Authors: Oni, Joshua , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293223 , vital:57066 , xlink:href="https://doi.org/10.1016/S0277-5387(00)00421-6"
- Description: This work reports on the kinetics of interaction of iron(II) tetrasulfophthalocyanine, [FeTSPc]4−, with dopamine (DA) and serotonin (5-HT). The interaction results in the coordination of dopamine and serotonin to [FeTSPc]4−, followed by internal electron transfer and the formation of [(DA+)FeITSPc]4− and [(5-HT+) FeITSPc]4− complexes, respectively. The rate constants for the coordination of dopamine or serotonin to [FeTSPc]4− and the formation of the FeITSPc species were found to be kf=6.8 and 9.3 dm3 mol−1 s−1, respectively. The equilibrium constants were 2.2×103 and 1.5×103 dm3 mol−1, respectively, for the interaction of dopamine or serotonin to [FeTSPc]4−.
- Full Text:
- Date Issued: 2000
Interaction of nitric oxide with cobalt (II) tetrasulfophthalocyanine
- Vilakazi, Sibulelo, Nyokong, Tebello
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
- Full Text:
- Date Issued: 2000
- Authors: Vilakazi, Sibulelo , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293235 , vital:57067 , xlink:href="https://doi.org/10.1016/S0277-5387(99)00373-3"
- Description: The interaction of nitric oxide (NO) with cobalt(II) tetrasulfophthalocyanine [Co(II)TSPc]4−) has been studied. Coordination of NO is accompanied by electron transfer from the central metal in [Co(II)TSPc]4−, the resulting complex being represented as [(NO−)Co(III)TSPc]4−. The rate constant for the formation of this species is kf=142±7 dm3 mol−1 s−1 and an equilibrium constant of 3.0±0.5×105 dm3 mol−1 was obtained. When adsorbed to a glassy carbon electrode, [Co(II)TSPc]4− catalyses the oxidation and reduction of NO, with a detection limit of the order of 10−9 mol dm−3. Ammonia and hydroxylamine are some of the reduction products obtained for the reduction of NO on [Co(II)TSPc]4−-modified glassy carbon electrodes.
- Full Text:
- Date Issued: 2000
Interaction of the neurotransmitter acetylcholine with aluminium, calcium and sodium
- Matlaba, Pulane M, Daya, Santy, Nyokong, Tebello
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
- Authors: Matlaba, Pulane M , Daya, Santy , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/293246 , vital:57068 , xlink:href="https://doi.org/10.1211/146080800128735890"
- Description: Binding of aluminium to acetylcholine has important biological implications particularly in Alzheimer's disease. An electrochemical technique, adsorptive cathodic stripping voltammetry, has been employed in this study to investigate the in-situ formation of a complex between aluminium and acetylcholine. The stability of the resulting complex was compared with that of the in-situ complexes formed between acetylcholine and sodium or calcium. From the shifts in the reduction potential of the metals on addition of acetylcholine it is concluded that a strong complex is formed between acetylcholine and aluminium. Much weaker complexes are formed between calcium or sodium and acetylcholine. These results have important implications in the aetiology of Alzheimer's disease-in which brain aluminium concentrations are known to be high and brain cholinergic function is lower than normal.
- Full Text:
- Date Issued: 2000
Intertidal population structure of the edible mollusc Turbo sarmaticus (Vetigastropoda) at an unexploited and exploited sites along the coast of the Eastern Cape Province, South Africa
- Foster, Gregory G, Hodgson, Alan N
- Authors: Foster, Gregory G , Hodgson, Alan N
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447403 , vital:74622 , https://doi.org/10.1080/15627020.2000.11657088
- Description: The intertidal population structure of the large edible gastropod Turbo sarmaticus was examined at four sites along the Eastern Cape Province of South Africa. One site was free from exploitation, two were subjected to low levels of exploitationand one was heavily exploited. Within the intertidal zone at all sites there was a size-related distribution, with smalleranimals being found towards the upper mid-shore and larger animals occurring in a downshore direction. The mean shore densities (1.2–animals/m2) and biomass (4.4–9.4 g/m2) of T. sarmaticus at the sites where there was no, or minimal, exploitation of animals were not significantly different (P0.001). However, the largest animals (up to 110mmshell length) were found at the unexploited site, an offshore island. The lowest density (0.2 animals/m2) and biomass (0.4 g/m2) of T. sarmaticus was recorded at the site where the exploitation of this gastropod was intense. In addition, no animals of a legally exploitable size (>70 mm shell length) were found. It is suggested that intense over-exploitation is threatening the population at this site.
- Full Text:
- Date Issued: 2000
- Authors: Foster, Gregory G , Hodgson, Alan N
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447403 , vital:74622 , https://doi.org/10.1080/15627020.2000.11657088
- Description: The intertidal population structure of the large edible gastropod Turbo sarmaticus was examined at four sites along the Eastern Cape Province of South Africa. One site was free from exploitation, two were subjected to low levels of exploitationand one was heavily exploited. Within the intertidal zone at all sites there was a size-related distribution, with smalleranimals being found towards the upper mid-shore and larger animals occurring in a downshore direction. The mean shore densities (1.2–animals/m2) and biomass (4.4–9.4 g/m2) of T. sarmaticus at the sites where there was no, or minimal, exploitation of animals were not significantly different (P0.001). However, the largest animals (up to 110mmshell length) were found at the unexploited site, an offshore island. The lowest density (0.2 animals/m2) and biomass (0.4 g/m2) of T. sarmaticus was recorded at the site where the exploitation of this gastropod was intense. In addition, no animals of a legally exploitable size (>70 mm shell length) were found. It is suggested that intense over-exploitation is threatening the population at this site.
- Full Text:
- Date Issued: 2000
Melatonin alters the photodegradation of paracetamol
- Anoopkumar-Dukie, Shailendra, Glass, Beverley D, Walker, Roderick B, Daya, Santylal
- Authors: Anoopkumar-Dukie, Shailendra , Glass, Beverley D , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184357 , vital:44211 , xlink:href="https://doi.org/10.1211/146080800128735755"
- Description: The effects of melatonin, a known free-radical scavenger, on paracetamol in the presence of UV irradiation was studied by use of HPLC. The experiments were performed in air and nitrogen. The results show that the rate of photodegradation of melatonin is faster in air than in nitrogen whereas that of paracetamol is similar in air and nitrogen. When the two drugs were combined, melatonin retarded the degradation of paracetamol for up to 6h in the presence of nitrogen. However, in the presence of air melatonin rapidly enhances the photodegradation of paracetamol. This study shows that a combination of melatonin and paracetamol in the presence of air and UV irradiation can lead to rapid inactivation of both agents, thus raising important concerns about the possible use of melatonin as sunscreen
- Full Text:
- Date Issued: 2000
- Authors: Anoopkumar-Dukie, Shailendra , Glass, Beverley D , Walker, Roderick B , Daya, Santylal
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184357 , vital:44211 , xlink:href="https://doi.org/10.1211/146080800128735755"
- Description: The effects of melatonin, a known free-radical scavenger, on paracetamol in the presence of UV irradiation was studied by use of HPLC. The experiments were performed in air and nitrogen. The results show that the rate of photodegradation of melatonin is faster in air than in nitrogen whereas that of paracetamol is similar in air and nitrogen. When the two drugs were combined, melatonin retarded the degradation of paracetamol for up to 6h in the presence of nitrogen. However, in the presence of air melatonin rapidly enhances the photodegradation of paracetamol. This study shows that a combination of melatonin and paracetamol in the presence of air and UV irradiation can lead to rapid inactivation of both agents, thus raising important concerns about the possible use of melatonin as sunscreen
- Full Text:
- Date Issued: 2000
Nigrobaetis Novikova and Kluge (Ephemeroptera Baetidae): first record and new species from southern Africa, with reassignment of one northern African species.
- Lugo-Ortiz, C R, de Moor, Ferdy C
- Authors: Lugo-Ortiz, C R , de Moor, Ferdy C
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452159 , vital:75108 , https://hdl.handle.net/10520/AJA10213589_279
- Description: Nigrobaetis bethuneae sp. n. (Ephemeroptera: Baetidae) is descriptionbed from larvae collected from the Cunene (Kunene) River between Angola and Namibia. The new species represents the first record of Nigrobaetis Novikova and Kluge from southern Africa and a considerable extension of the distribution range for the genus. Nigrobaetis bethuneae is characterized by the presence of a small interantennal carina, arrangement of dorsal setae on the labrum, mandibular denticulation and setation, apicolaterally bluntly pointed labial palp segment 3, absence of hind-wing pads, presence of the first pair of gills, and general abdominal coloration. Ecological data on the new species are provided. The Algerian species Baetis rhithralis Soldan, previously considered to belong in Diphetor Waltz and McCafferty, is transferred to Nigrobaetis, and the biogeographic implications of the new assignment are discussed.
- Full Text:
- Date Issued: 2000
- Authors: Lugo-Ortiz, C R , de Moor, Ferdy C
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452159 , vital:75108 , https://hdl.handle.net/10520/AJA10213589_279
- Description: Nigrobaetis bethuneae sp. n. (Ephemeroptera: Baetidae) is descriptionbed from larvae collected from the Cunene (Kunene) River between Angola and Namibia. The new species represents the first record of Nigrobaetis Novikova and Kluge from southern Africa and a considerable extension of the distribution range for the genus. Nigrobaetis bethuneae is characterized by the presence of a small interantennal carina, arrangement of dorsal setae on the labrum, mandibular denticulation and setation, apicolaterally bluntly pointed labial palp segment 3, absence of hind-wing pads, presence of the first pair of gills, and general abdominal coloration. Ecological data on the new species are provided. The Algerian species Baetis rhithralis Soldan, previously considered to belong in Diphetor Waltz and McCafferty, is transferred to Nigrobaetis, and the biogeographic implications of the new assignment are discussed.
- Full Text:
- Date Issued: 2000
Photocatalytic properties of neodymium diphthalocyanine towards the transformation of 4-chlorophenol
- Nensala, Ngudiankama, Nyokong, Tebello
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:58491 , xlink:href="https://doi.org/10.1016/S1381-1169(00)00283-1"
- Description: Photolysis of aqueous solutions of 4-chlorophenol (4-Cp) in the presence of solid neodymium diphthalocyanine ([Pc(−2)NdPc(−2)]−) and oxygen using visible and ultraviolet (UV) radiation resulted in the formation of a number of products. For photolysis in the visible region, phenol, benzoquinone, hydroquinone were observed as intermediates and 4-chlorocatechol (4-CC) as the main product; intermediates similar to those observed for visible photolysis were obtained. Langmuir–Hinshelwood kinetic model was used for treatment of photochemical data.
- Full Text:
- Date Issued: 2000
Photocatalytic properties of neodymium diphthalocyanine towards the transformation of 4-chlorophenol
- Authors: Nensala, Ngudiankama , Nyokong, Tebello
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/${Handle} , vital:58491 , xlink:href="https://doi.org/10.1016/S1381-1169(00)00283-1"
- Description: Photolysis of aqueous solutions of 4-chlorophenol (4-Cp) in the presence of solid neodymium diphthalocyanine ([Pc(−2)NdPc(−2)]−) and oxygen using visible and ultraviolet (UV) radiation resulted in the formation of a number of products. For photolysis in the visible region, phenol, benzoquinone, hydroquinone were observed as intermediates and 4-chlorocatechol (4-CC) as the main product; intermediates similar to those observed for visible photolysis were obtained. Langmuir–Hinshelwood kinetic model was used for treatment of photochemical data.
- Full Text:
- Date Issued: 2000
Review of policies and legislation influencing the sustainable use of South Africa's indigenous Woodlands
- Willis, Carla B, Geach, Bev S, Versfeld, Dirk, Shackleton, Charlie M
- Authors: Willis, Carla B , Geach, Bev S , Versfeld, Dirk , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182810 , vital:43881 , xlink:href="https://hdl.handle.net/10520/AJA10231765_60"
- Description: The recent completion of the South African National Land-Cover Database and the Vegetation Map of South Africa, Swaziland and Lesotho, allows for the first time a comparison to be made on a national scale between the current and potential distribution of 'natural' vegetation resources. This article compares the distribution and location of woodland-type vegetation categories defined within the National Land-Cover data and the equivalent 'Savanna-thicket Biomes' class defined within the Vegetation Mapdata. Significant differences were found, both in terms of the total areal extent, as well as the actual spatial distribution of these two data sets. These differences are a measure of the inherent mapping accuracies of each source, but rather an illustration of boundary delineation distinctions that are a result of different data sources, mapping objectives and information classes, that must be noted when comparing two essentially similar information sets.
- Full Text:
- Date Issued: 2000
- Authors: Willis, Carla B , Geach, Bev S , Versfeld, Dirk , Shackleton, Charlie M
- Date: 2000
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182810 , vital:43881 , xlink:href="https://hdl.handle.net/10520/AJA10231765_60"
- Description: The recent completion of the South African National Land-Cover Database and the Vegetation Map of South Africa, Swaziland and Lesotho, allows for the first time a comparison to be made on a national scale between the current and potential distribution of 'natural' vegetation resources. This article compares the distribution and location of woodland-type vegetation categories defined within the National Land-Cover data and the equivalent 'Savanna-thicket Biomes' class defined within the Vegetation Mapdata. Significant differences were found, both in terms of the total areal extent, as well as the actual spatial distribution of these two data sets. These differences are a measure of the inherent mapping accuracies of each source, but rather an illustration of boundary delineation distinctions that are a result of different data sources, mapping objectives and information classes, that must be noted when comparing two essentially similar information sets.
- Full Text:
- Date Issued: 2000