Synthesis, spectroscopic and electrochemical properties of manganese, nickel and iron octakis-(2-diethylaminoethanethiol)-phthalocyanine
- Adebayo, A I, Nyokong, Tebello
- Authors: Adebayo, A I , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6563 , http://hdl.handle.net/10962/d1004122
- Description: The syntheses, spectroscopic and electrochemical properties of manganese (3), nickel (4) and iron (5) phthalocyanine complexes, octa-substituted at the peripheral positions with diethlyaminoethanethiol substituent, are reported. The electrochemistry of these complexes and the corresponding cobalt complex (6) are reported. Complex 3 showed two reversible reduction couples attributed to the MnIIIPc−2/MnIIPc−2 (E½ = −0.12 V versus Ag|AgCl) and MnIIPc−2/MnIIPc−3 (E½ = −0.82 V versus Ag|AgCl) species. Two ring-based reduction couples were also observed for complex 4. Two reduction couples, assigned to the FeIIPc−2/FeIPc−2 (E½ = −0.35 V versus Ag|AgCl) and FeIPc−2/FeIPc−3 (E½ = −0.96 V versus Ag|AgCl) species, and an oxidation couple, attributed to FeIIIPc−2/FeIIPc−2 (E½ = 0.26 V versus Ag|AgCl) species, were observed. For complex 6, two reductions and one oxidation were also observed with the potential range of 1.2 to −1.8 V versus Ag|AgCl Spectroelectrochemical studies were used to confirm some of the assigned processes.
- Full Text:
- Date Issued: 2009
- Authors: Adebayo, A I , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6563 , http://hdl.handle.net/10962/d1004122
- Description: The syntheses, spectroscopic and electrochemical properties of manganese (3), nickel (4) and iron (5) phthalocyanine complexes, octa-substituted at the peripheral positions with diethlyaminoethanethiol substituent, are reported. The electrochemistry of these complexes and the corresponding cobalt complex (6) are reported. Complex 3 showed two reversible reduction couples attributed to the MnIIIPc−2/MnIIPc−2 (E½ = −0.12 V versus Ag|AgCl) and MnIIPc−2/MnIIPc−3 (E½ = −0.82 V versus Ag|AgCl) species. Two ring-based reduction couples were also observed for complex 4. Two reduction couples, assigned to the FeIIPc−2/FeIPc−2 (E½ = −0.35 V versus Ag|AgCl) and FeIPc−2/FeIPc−3 (E½ = −0.96 V versus Ag|AgCl) species, and an oxidation couple, attributed to FeIIIPc−2/FeIIPc−2 (E½ = 0.26 V versus Ag|AgCl) species, were observed. For complex 6, two reductions and one oxidation were also observed with the potential range of 1.2 to −1.8 V versus Ag|AgCl Spectroelectrochemical studies were used to confirm some of the assigned processes.
- Full Text:
- Date Issued: 2009
The WHO UNESCO FIP Pharmacy Education Taskforce (commentary)
- Anderson, Claire, Bates, Ian, Beck, Diane, Penick Brock, Tina, Futter, William T, Mercer, Hugo, Rouse, Mike, Whitmarsh, Sarah, Wuliji, Tana, Yonemura, Akemi
- Authors: Anderson, Claire , Bates, Ian , Beck, Diane , Penick Brock, Tina , Futter, William T , Mercer, Hugo , Rouse, Mike , Whitmarsh, Sarah , Wuliji, Tana , Yonemura, Akemi
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6347 , http://hdl.handle.net/10962/d1006020
- Description: Pharmacists' roles are evolving from that of compounders and dispensers of medicines to that of experts on medicines within multidisciplinary health care teams. In the developing country context, the pharmacy is often the most accessible or even the sole point of access to health care advice and services. Because of their knowledge of medicines and clinical therapeutics, pharmacists are suitably placed for task shifting in health care and could be further trained to undertake functions such as clinical management and laboratory diagnostics. Indeed, pharmacists have been shown to be willing, competent, and cost-effective providers of what the professional literature calls "pharmaceutical care interventions"; however, internationally, there is an underuse of pharmacists for patient care and public health efforts. A coordinated and multifaceted effort to advance workforce planning, training and education is needed in order to prepare an adequate number of well-trained pharmacists for such roles. Acknowledging that health care needs can vary across geography and culture, an international group of key stakeholders in pharmacy education and global health has reached unanimous agreement that pharmacy education must be quality-driven and directed towards societal health care needs, the services required to meet those needs, the competences necessary to provide these services and the education needed to ensure those competences. Using that framework, this commentary describes the Pharmacy Education Taskforce of the World Health Organization, United Nations Educational, Scientific and Cultural Organization and the International Pharmaceutical Federation Global Pharmacy and the Education Action Plan 2008–2010, including the foundation, domains, objectives and outcome measures, and includes several examples of current activities within this scope.
- Full Text:
- Date Issued: 2009
- Authors: Anderson, Claire , Bates, Ian , Beck, Diane , Penick Brock, Tina , Futter, William T , Mercer, Hugo , Rouse, Mike , Whitmarsh, Sarah , Wuliji, Tana , Yonemura, Akemi
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6347 , http://hdl.handle.net/10962/d1006020
- Description: Pharmacists' roles are evolving from that of compounders and dispensers of medicines to that of experts on medicines within multidisciplinary health care teams. In the developing country context, the pharmacy is often the most accessible or even the sole point of access to health care advice and services. Because of their knowledge of medicines and clinical therapeutics, pharmacists are suitably placed for task shifting in health care and could be further trained to undertake functions such as clinical management and laboratory diagnostics. Indeed, pharmacists have been shown to be willing, competent, and cost-effective providers of what the professional literature calls "pharmaceutical care interventions"; however, internationally, there is an underuse of pharmacists for patient care and public health efforts. A coordinated and multifaceted effort to advance workforce planning, training and education is needed in order to prepare an adequate number of well-trained pharmacists for such roles. Acknowledging that health care needs can vary across geography and culture, an international group of key stakeholders in pharmacy education and global health has reached unanimous agreement that pharmacy education must be quality-driven and directed towards societal health care needs, the services required to meet those needs, the competences necessary to provide these services and the education needed to ensure those competences. Using that framework, this commentary describes the Pharmacy Education Taskforce of the World Health Organization, United Nations Educational, Scientific and Cultural Organization and the International Pharmaceutical Federation Global Pharmacy and the Education Action Plan 2008–2010, including the foundation, domains, objectives and outcome measures, and includes several examples of current activities within this scope.
- Full Text:
- Date Issued: 2009
Curiosity first, applications later
- Berold, Robert, Limson, Janice L
- Authors: Berold, Robert , Limson, Janice L
- Date: 2009
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7188 , http://hdl.handle.net/10962/d1006281 , http://www.sajs.co.za/sites/default/files/publications/pdf/1-4-1-PB.pdf , Nyokong, Tebello
- Description: Tebello Nyokong speaks to Robert Berold and Janice Limson about her career as a chemist. Tebello Nyokong, who holds a research chair in medicinal chemistry and nanotechnology at Rhodes University, has become the first South African scientist to win the L’Oreal-UNESCO award for women in science, in the physical sciences. Only one laureate is selected from each of five world regions, and Nyokong is the 2009 laureate for Africa and the Arab states. She and the winners from the other four regions travel to Paris in March to each accept the award and a generous prize of close to R1 million. Nyokong now heads the new Nanotechnology Innovation Centre for medical sensors: the biggest single research investment in the history of Rhodes. Linked to other nanotechnology centres in the country, it is designed to bridge the gap between research and the market.
- Full Text:
- Date Issued: 2009
- Authors: Berold, Robert , Limson, Janice L
- Date: 2009
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7188 , http://hdl.handle.net/10962/d1006281 , http://www.sajs.co.za/sites/default/files/publications/pdf/1-4-1-PB.pdf , Nyokong, Tebello
- Description: Tebello Nyokong speaks to Robert Berold and Janice Limson about her career as a chemist. Tebello Nyokong, who holds a research chair in medicinal chemistry and nanotechnology at Rhodes University, has become the first South African scientist to win the L’Oreal-UNESCO award for women in science, in the physical sciences. Only one laureate is selected from each of five world regions, and Nyokong is the 2009 laureate for Africa and the Arab states. She and the winners from the other four regions travel to Paris in March to each accept the award and a generous prize of close to R1 million. Nyokong now heads the new Nanotechnology Innovation Centre for medical sensors: the biggest single research investment in the history of Rhodes. Linked to other nanotechnology centres in the country, it is designed to bridge the gap between research and the market.
- Full Text:
- Date Issued: 2009
Possible trace fossils of putative termite origin in the Lower Jurassic (Karoo Supergroup) of South Africa and Lesotho
- Bordy, Emese M, Bumby, A J, Catuneanu, O, Eriksson, P G
- Authors: Bordy, Emese M , Bumby, A J , Catuneanu, O , Eriksson, P G
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6732 , http://hdl.handle.net/10962/d1007541
- Description: Complex structures in the sandstones of the Lower Jurassic aeolian Clarens Formation (Karoo Supergroup) are found at numerous localities throughout southern Africa, and can be assigned to five distinct architectural groups: (1) up to 3.3-m high, free-standing, slab-shaped forms of bioturbated sandstones with elliptical bases, orientated buttresses and an interconnecting large burrow system; (2) up to 1.2-m high, free-standing, irregular forms of bioturbated sandstones with 2-cm to 4-cm thick, massive walls, empty chambers and vertical shafts; (3) about 0.15-m to 0.25-m high, mainly bulbous, multiple forms with thin walls (<2 cm), hollow chambers with internal pillars and bridges; (4) about 0.15-m to 0.2-m (maximum 1-m) high, free-standing forms of aggregated solitary spheres associated with massive horizontal, orientated capsules or tubes, and meniscate tubes; and (5) about 5 cmin diameter, ovoid forms with weak internal shelving in a close-fitting cavity. Based on size, wall thickness, orientation and the presence of internal chambers, these complex structures are tentatively interpreted as ichnofossils of an Early Jurassic social organism; the different architectures are reflective of the different behaviours of more than one species, the history of structural change in architectural forms (ontogenetic series) or an architectural adaptation to local palaeoclimatic variability. While exact modern equivalents are unknown, some of these ichnofossils are comparable to nests (or parts of nests) constructed by extant termites, and thus these Jurassic structures are very tentatively interpreted here as having been made by a soil-dwelling social organism, probably of termite origin. This southern African discovery, along with reported Triassic and Jurassic termite ichnofossils from North America, supports previous hypotheses that sociality in insects, particularity in termites, likely evolved prior to the Pangea breakup in the Early Mesozoic.
- Full Text:
- Date Issued: 2009
- Authors: Bordy, Emese M , Bumby, A J , Catuneanu, O , Eriksson, P G
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6732 , http://hdl.handle.net/10962/d1007541
- Description: Complex structures in the sandstones of the Lower Jurassic aeolian Clarens Formation (Karoo Supergroup) are found at numerous localities throughout southern Africa, and can be assigned to five distinct architectural groups: (1) up to 3.3-m high, free-standing, slab-shaped forms of bioturbated sandstones with elliptical bases, orientated buttresses and an interconnecting large burrow system; (2) up to 1.2-m high, free-standing, irregular forms of bioturbated sandstones with 2-cm to 4-cm thick, massive walls, empty chambers and vertical shafts; (3) about 0.15-m to 0.25-m high, mainly bulbous, multiple forms with thin walls (<2 cm), hollow chambers with internal pillars and bridges; (4) about 0.15-m to 0.2-m (maximum 1-m) high, free-standing forms of aggregated solitary spheres associated with massive horizontal, orientated capsules or tubes, and meniscate tubes; and (5) about 5 cmin diameter, ovoid forms with weak internal shelving in a close-fitting cavity. Based on size, wall thickness, orientation and the presence of internal chambers, these complex structures are tentatively interpreted as ichnofossils of an Early Jurassic social organism; the different architectures are reflective of the different behaviours of more than one species, the history of structural change in architectural forms (ontogenetic series) or an architectural adaptation to local palaeoclimatic variability. While exact modern equivalents are unknown, some of these ichnofossils are comparable to nests (or parts of nests) constructed by extant termites, and thus these Jurassic structures are very tentatively interpreted here as having been made by a soil-dwelling social organism, probably of termite origin. This southern African discovery, along with reported Triassic and Jurassic termite ichnofossils from North America, supports previous hypotheses that sociality in insects, particularity in termites, likely evolved prior to the Pangea breakup in the Early Mesozoic.
- Full Text:
- Date Issued: 2009
Fluorescence studies of quantum dots and zinc tetraamino phthalocyanine conjugates
- Britton, Jonathan, Antunes, Edith M, Nyokong, Tebello
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6565 , http://hdl.handle.net/10962/d1004124
- Description: CdTe Qds capped with mercapto propionic acid (MPA) were covalently linked to zinc tetraamino phthalocyanine (ZnTAPc) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of the formation of an amide bond between ZnTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and a mixture of QDs and ZnTAPc (i.e. without chemical linking) showed Förster resonance energy transfer (FRET). ZnTAPc quenched the QDs emission, giving quenching constants in the order of 103 M−1.
- Full Text:
- Date Issued: 2009
- Authors: Britton, Jonathan , Antunes, Edith M , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6565 , http://hdl.handle.net/10962/d1004124
- Description: CdTe Qds capped with mercapto propionic acid (MPA) were covalently linked to zinc tetraamino phthalocyanine (ZnTAPc) using N-ethyl-N(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) as the coupling agents. The results presented give evidence in favour of the formation of an amide bond between ZnTAPc and CdTe QDs. Both the linked ZnTAPc–QD complexes and a mixture of QDs and ZnTAPc (i.e. without chemical linking) showed Förster resonance energy transfer (FRET). ZnTAPc quenched the QDs emission, giving quenching constants in the order of 103 M−1.
- Full Text:
- Date Issued: 2009
Luminescence lifetime components in quartz: influence of irradiation and annealing
- Chithambo, Makaiko L, Ogundare, F O
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6811 , http://hdl.handle.net/10962/d1004304
- Description: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900 °C, beta irradiation dose as high as 1700 Gy, and temperature of stimulation up to 200 °C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200 Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of 35 μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18 μs when the annealing temperature is changed from 600 to 900 °C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing.
- Full Text:
- Date Issued: 2009
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6811 , http://hdl.handle.net/10962/d1004304
- Description: Pulsed optically stimulated luminescence measured from quartz under certain combinations of annealing and measurement temperature can be resolved into multiple lifetime components. We have studied the influence on these lifetime components of annealing temperature up to 900 °C, beta irradiation dose as high as 1700 Gy, and temperature of stimulation up to 200 °C. Although the time-resolved spectra from which the lifetimes are determined may be measured without heating between irradiation and measurement, a necessary protocol in steady-state optical stimulation applications, studies reported in this paper have been augmented with investigations on the effect of temperature and duration of preheating on the principal and secondary lifetimes. Luminescence spectra for measurements up to 200 Gy consist of a single lifetime but two components occur thereafter, both are independent of radiation dose. The principal lifetime of 35 μs is not affected by temperature of anneal whereas the secondary lifetime increases from 9 to 18 μs when the annealing temperature is changed from 600 to 900 °C. The dependence of both the principal and secondary luminescence lifetimes on measurement temperature can be explained by thermal quenching of the associated luminescence. However, the influence of irradiation, preheating, and annealing on the lifetimes can be explained with reference to an energy band scheme in which the primary mechanism in the processes leading up to luminescence emission is the change in concentration of holes at various luminescence centres caused by annealing.
- Full Text:
- Date Issued: 2009
Plants for health, life and spirit in Africa : implications for biodiversity and cultural diversity conservation
- Cocks, Michelle L, Dold, Anthony P
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6617 , http://hdl.handle.net/10962/d1016225
- Description: [From Introduction] Natural resources are often only perceived as contributing to rural livelihoods through food production and household welfare. There is a growing wealth of information capturing the direct-use values of the environment and consequent recognition of natural resources as being “the poor man's overcoat”. These approaches, however, have failed to fully account for the various ways in which different groups of people make use of, and find value in biodiversity. New developments within the field of anthropology have begun to explore the relationship between biodiversity and human diversity. This view has largely come about because many of the areas of highest biological diversity are inhabited by indigenous and traditional people, providing what the Declaration of Belem (1988) calls an 'inextricable link' between biological and cultural diversity (Posey 1999). The term bio-cultural diversity was introduced by Posey in 1999 to describe the concept denoting this link. , Funding was received from the South Africa-Netherlands Programme on Alternatives in Development (SANPAD) and the International Foundation of Science (IFS)
- Full Text:
- Date Issued: 2009
- Authors: Cocks, Michelle L , Dold, Anthony P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6617 , http://hdl.handle.net/10962/d1016225
- Description: [From Introduction] Natural resources are often only perceived as contributing to rural livelihoods through food production and household welfare. There is a growing wealth of information capturing the direct-use values of the environment and consequent recognition of natural resources as being “the poor man's overcoat”. These approaches, however, have failed to fully account for the various ways in which different groups of people make use of, and find value in biodiversity. New developments within the field of anthropology have begun to explore the relationship between biodiversity and human diversity. This view has largely come about because many of the areas of highest biological diversity are inhabited by indigenous and traditional people, providing what the Declaration of Belem (1988) calls an 'inextricable link' between biological and cultural diversity (Posey 1999). The term bio-cultural diversity was introduced by Posey in 1999 to describe the concept denoting this link. , Funding was received from the South Africa-Netherlands Programme on Alternatives in Development (SANPAD) and the International Foundation of Science (IFS)
- Full Text:
- Date Issued: 2009
A test for Allee effects in the self-incompatible wasp-pollinated milkweed Gomphocarpus physocarpus
- Coombs, Gareth, Peter, Craig I, Johnson, Steven D
- Authors: Coombs, Gareth , Peter, Craig I , Johnson, Steven D
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6511 , http://hdl.handle.net/10962/d1005938 , http://dx.doi.org/10.1111/j.1442-9993.2009.01976.x
- Description: It has been suggested that plants which are good colonizers will generally have either an ability to self-fertilize or a generalist pollination system. This prediction is based on the idea that these reproductive traits should confer resistance to Allee effects in founder populations and was tested using Gomphocarpus physocarpus (Asclepiadoideae; Apocynaceae), a species native to South Africa that is invasive in other parts of the world. We found no significant relationships between the size of G. physocarpus populations and various measures of pollination success (pollen deposition, pollen removal, and pollen transfer efficiency) and fruit set. A breeding system experiment showed that plants in a South African population are genetically self-incompatible and thus obligate outcrossers. Out-crossing is further enhanced by mechanical reconfiguration of removed pollinaria before the pollinia can be deposited. Selfpollination is reduced when such reconfiguration exceeds the average duration of pollinator visits to a plant. Observations suggest that a wide variety of wasp species in the genera Belonogaster and Polistes (Vespidae) are the primary pollinators. We conclude that efficient pollination of plants in small founding populations, resulting from their generalist wasp-pollination system, contributes in part to the colonizing success of G. physocarpus. The presence of similar wasps in other parts of the world has evidently facilitated the expansion of the range of this milkweed.
- Full Text:
- Date Issued: 2009
- Authors: Coombs, Gareth , Peter, Craig I , Johnson, Steven D
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6511 , http://hdl.handle.net/10962/d1005938 , http://dx.doi.org/10.1111/j.1442-9993.2009.01976.x
- Description: It has been suggested that plants which are good colonizers will generally have either an ability to self-fertilize or a generalist pollination system. This prediction is based on the idea that these reproductive traits should confer resistance to Allee effects in founder populations and was tested using Gomphocarpus physocarpus (Asclepiadoideae; Apocynaceae), a species native to South Africa that is invasive in other parts of the world. We found no significant relationships between the size of G. physocarpus populations and various measures of pollination success (pollen deposition, pollen removal, and pollen transfer efficiency) and fruit set. A breeding system experiment showed that plants in a South African population are genetically self-incompatible and thus obligate outcrossers. Out-crossing is further enhanced by mechanical reconfiguration of removed pollinaria before the pollinia can be deposited. Selfpollination is reduced when such reconfiguration exceeds the average duration of pollinator visits to a plant. Observations suggest that a wide variety of wasp species in the genera Belonogaster and Polistes (Vespidae) are the primary pollinators. We conclude that efficient pollination of plants in small founding populations, resulting from their generalist wasp-pollination system, contributes in part to the colonizing success of G. physocarpus. The presence of similar wasps in other parts of the world has evidently facilitated the expansion of the range of this milkweed.
- Full Text:
- Date Issued: 2009
Don Maclennan (1929-2009): obituary
- Authors: Cornwell, Gareth D N
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6118 , http://hdl.handle.net/10962/d1004620
- Description: Donald Alasdair Calum Maclennan, the South African playwright, poet and critic, died in Port Elizabeth on February 9, 2009, at the age of 79. He will be remembered chiefly for the poetry that he published in the last three decades of his life.
- Full Text:
- Date Issued: 2009
- Authors: Cornwell, Gareth D N
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6118 , http://hdl.handle.net/10962/d1004620
- Description: Donald Alasdair Calum Maclennan, the South African playwright, poet and critic, died in Port Elizabeth on February 9, 2009, at the age of 79. He will be remembered chiefly for the poetry that he published in the last three decades of his life.
- Full Text:
- Date Issued: 2009
A common framework for lattice-valued uniform spaces and probabilistic uniform limit spaces
- Craig, Andrew P K, Jäger, Gunter
- Authors: Craig, Andrew P K , Jäger, Gunter
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6784 , http://hdl.handle.net/10962/d1006927
- Description: We study a category of lattice-valued uniform convergence spaces where the lattice is enriched by two algebraic operations. This general setting allows us to view the category of lattice-valued uniform spaces as a reflective subcategory of our category, and the category of probabilistic uniform limit spaces as a coreflective subcategory.
- Full Text:
- Date Issued: 2009
- Authors: Craig, Andrew P K , Jäger, Gunter
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6784 , http://hdl.handle.net/10962/d1006927
- Description: We study a category of lattice-valued uniform convergence spaces where the lattice is enriched by two algebraic operations. This general setting allows us to view the category of lattice-valued uniform spaces as a reflective subcategory of our category, and the category of probabilistic uniform limit spaces as a coreflective subcategory.
- Full Text:
- Date Issued: 2009
Municipal commonage policy and livestock owners : findings from the Eastern Cape, South Africa
- Davenport, Nicholas A, Gambiza, James
- Authors: Davenport, Nicholas A , Gambiza, James
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6628 , http://hdl.handle.net/10962/d1006820
- Description: The new African National Congress government announced after 1994 that municipal commonage would be a pillar of their land reform programme. The Department of Land Affairs spearheaded this by acquiring new land to complement the existing ‘old’ commonages. The aim of old commonage was to supplement the income of poor urban residents through the subsistence user system whereas new commonage was intended as a ‘stepping stone’ for emergent farmers. We investigated the differences between old and new commonage farmers as well as how they perceived the Makana local municipality's capacity to manage the commonage. The results showed that local institutions were weak. Only 46% of the old commonage farmers were members of a local livestock association whereas 74% of the new commonage farmers were members. Most old commonage farmers (59%) were dissatisfied with local government's management of the commonage. In contrast, only 37% of the new commonage farmers were dissatisfied with the management of the commonage. There were no differences between old and new commonage farmers in terms of livestock owners’ characteristics and mean annual net direct-use value of livestock. There were also no differences in the age of the two types of commonage farmers. Furthermore, there was no association between the type of commonage and level of education. The mean annual net direct-use value of livestock on old commonage was R6308 compared with R9707 on new commonage. Although the income from livestock for new commonage farmers varied slightly from that of old commonage farmers, the annual productive output per farmer on old commonage was R473 ha−1, three times higher than that of new commonage farmers which was R134 ha−1. We suggest that new land policy legislation is needed in which poverty as well as the legal arrangements between all stakeholders is clearly defined. Furthermore, national departments need to be more involved with local municipalities to increase local management capacity.
- Full Text:
- Date Issued: 2009
- Authors: Davenport, Nicholas A , Gambiza, James
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6628 , http://hdl.handle.net/10962/d1006820
- Description: The new African National Congress government announced after 1994 that municipal commonage would be a pillar of their land reform programme. The Department of Land Affairs spearheaded this by acquiring new land to complement the existing ‘old’ commonages. The aim of old commonage was to supplement the income of poor urban residents through the subsistence user system whereas new commonage was intended as a ‘stepping stone’ for emergent farmers. We investigated the differences between old and new commonage farmers as well as how they perceived the Makana local municipality's capacity to manage the commonage. The results showed that local institutions were weak. Only 46% of the old commonage farmers were members of a local livestock association whereas 74% of the new commonage farmers were members. Most old commonage farmers (59%) were dissatisfied with local government's management of the commonage. In contrast, only 37% of the new commonage farmers were dissatisfied with the management of the commonage. There were no differences between old and new commonage farmers in terms of livestock owners’ characteristics and mean annual net direct-use value of livestock. There were also no differences in the age of the two types of commonage farmers. Furthermore, there was no association between the type of commonage and level of education. The mean annual net direct-use value of livestock on old commonage was R6308 compared with R9707 on new commonage. Although the income from livestock for new commonage farmers varied slightly from that of old commonage farmers, the annual productive output per farmer on old commonage was R473 ha−1, three times higher than that of new commonage farmers which was R134 ha−1. We suggest that new land policy legislation is needed in which poverty as well as the legal arrangements between all stakeholders is clearly defined. Furthermore, national departments need to be more involved with local municipalities to increase local management capacity.
- Full Text:
- Date Issued: 2009
Pointfree pseudocompactness revisited
- Authors: Dube, T , Matutu, Phethiwe P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6781 , http://hdl.handle.net/10962/d1006924
- Description: We give several internal and external characterizations of pseudocompactness in frames which extend (and transcend) analogous characterizations in topological spaces. In the case of internal characterizations we do not make reference (explicitly or implicitly) to the reals.
- Full Text:
- Date Issued: 2009
- Authors: Dube, T , Matutu, Phethiwe P
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6781 , http://hdl.handle.net/10962/d1006924
- Description: We give several internal and external characterizations of pseudocompactness in frames which extend (and transcend) analogous characterizations in topological spaces. In the case of internal characterizations we do not make reference (explicitly or implicitly) to the reals.
- Full Text:
- Date Issued: 2009
Treating posttraumatic stress disorder in South Africa : an integrative model grounded in case-based research
- Authors: Edwards, David J A
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6232 , http://hdl.handle.net/10962/d1007782
- Description: The article presents a model for formulating and planning treatment for post-traumatic stress disorder (PTSD) in South Africa derived from the existing literature and in conjunction with a review of a series of studies of cases treated using the guidelines of Ehlers and Clark's cognitive therapy. It is argued that the construction of psychotherapies (or even components of psychotherapy) for PTSD in terms of traditional categories ("psychodynamic", "cognitive-behavioural", "narrative" etc.) is misleading and unhelpful. Instead, superordinate concepts derived from thinking about evidence-based practice provide a more grounded focus on the practical issues faced by therapists treating PTSD. These concepts, which include competences and metcacompetences, therapist responsiveness, stages of therapy and case formulation, provide a basis for a genuinely integrative approach. The proposed model suggests seven broad areas of clinical focus for work with PTSD which can be arranged at three levels of priority: level 1 crisis intervention and stabilization; level 2 promoting engagement with treatment, and level 3 selection, sequencing and timing of active treatment interventions. Material from the case series is used to illustrate the application of the model.
- Full Text:
- Date Issued: 2009
- Authors: Edwards, David J A
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6232 , http://hdl.handle.net/10962/d1007782
- Description: The article presents a model for formulating and planning treatment for post-traumatic stress disorder (PTSD) in South Africa derived from the existing literature and in conjunction with a review of a series of studies of cases treated using the guidelines of Ehlers and Clark's cognitive therapy. It is argued that the construction of psychotherapies (or even components of psychotherapy) for PTSD in terms of traditional categories ("psychodynamic", "cognitive-behavioural", "narrative" etc.) is misleading and unhelpful. Instead, superordinate concepts derived from thinking about evidence-based practice provide a more grounded focus on the practical issues faced by therapists treating PTSD. These concepts, which include competences and metcacompetences, therapist responsiveness, stages of therapy and case formulation, provide a basis for a genuinely integrative approach. The proposed model suggests seven broad areas of clinical focus for work with PTSD which can be arranged at three levels of priority: level 1 crisis intervention and stabilization; level 2 promoting engagement with treatment, and level 3 selection, sequencing and timing of active treatment interventions. Material from the case series is used to illustrate the application of the model.
- Full Text:
- Date Issued: 2009
Who uses the fishery resources in South Africa’s largest impoundment? Characterising subsistence and recreational fishing sectors on Lake Gariep
- Ellender, Bruce R, Weyl, Olaf L F, Winker, A Henning
- Authors: Ellender, Bruce R , Weyl, Olaf L F , Winker, A Henning
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6778 , http://hdl.handle.net/10962/d1008088
- Description: The African Union’s prioritisation of inland fisheries as an investment area for poverty alleviation and regional economic development will require the development of management plans. These should be based on sound knowledge of the social dynamics of the resource users. In South Africa the social dynamics of resource users of inland fisheries have never been assessed. The purpose of this study was to assess the human dimensions of the anglers utilising the fishery in Lake Gariep, South Africa’s largest impoundment. The study was based on 357 first-time interviews conducted on the lakeshore between October 2006 and December 2007. Anglers were categorised as recreational (39%) or subsistence (61%) based on their residency, occupation, primary motivation for angling, mode of transport and gear use. Subsistence anglers were local (99%), residing within 10 km of the place where they were interviewed, while recreational anglers included both local resident and non-resident members. The racial composition of anglers was dependent on user group and differed significantly (p ≤ 0.05) from the demographic composition of the regional population. Recreational anglers were predominantly White (≥ 60% of interviews) and Coloured (≥ 25%), while 84% of subsistence anglers were Coloured and 16% Black African. Most recreational anglers had permanent employment or were pensioners while <30% of subsistence anglers were permanently employed. Most recreational users (82%) accessed the lake with their own vehicle while subsistence anglers mainly walked (63%) or used a bicycle (28%). Recreational interviewees either consumed (59%), sold (11%), gave away (10%) or released (20%) some of their catch. Subsistence anglers either ate their catch (53%) and/or sold (41%) their catch. Within the subsistence sector no anglers released fish after capture or gave some of the catch away. We conclude that this inland fishery contributes to the livelihood of the rural poor who use the lake on a subsistence basis and that recreational-angler based tourism may contribute to increased income and employment opportunities through related service industries.
- Full Text:
- Date Issued: 2009
- Authors: Ellender, Bruce R , Weyl, Olaf L F , Winker, A Henning
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6778 , http://hdl.handle.net/10962/d1008088
- Description: The African Union’s prioritisation of inland fisheries as an investment area for poverty alleviation and regional economic development will require the development of management plans. These should be based on sound knowledge of the social dynamics of the resource users. In South Africa the social dynamics of resource users of inland fisheries have never been assessed. The purpose of this study was to assess the human dimensions of the anglers utilising the fishery in Lake Gariep, South Africa’s largest impoundment. The study was based on 357 first-time interviews conducted on the lakeshore between October 2006 and December 2007. Anglers were categorised as recreational (39%) or subsistence (61%) based on their residency, occupation, primary motivation for angling, mode of transport and gear use. Subsistence anglers were local (99%), residing within 10 km of the place where they were interviewed, while recreational anglers included both local resident and non-resident members. The racial composition of anglers was dependent on user group and differed significantly (p ≤ 0.05) from the demographic composition of the regional population. Recreational anglers were predominantly White (≥ 60% of interviews) and Coloured (≥ 25%), while 84% of subsistence anglers were Coloured and 16% Black African. Most recreational anglers had permanent employment or were pensioners while <30% of subsistence anglers were permanently employed. Most recreational users (82%) accessed the lake with their own vehicle while subsistence anglers mainly walked (63%) or used a bicycle (28%). Recreational interviewees either consumed (59%), sold (11%), gave away (10%) or released (20%) some of their catch. Subsistence anglers either ate their catch (53%) and/or sold (41%) their catch. Within the subsistence sector no anglers released fish after capture or gave some of the catch away. We conclude that this inland fishery contributes to the livelihood of the rural poor who use the lake on a subsistence basis and that recreational-angler based tourism may contribute to increased income and employment opportunities through related service industries.
- Full Text:
- Date Issued: 2009
New soluble methylendioxy-phenoxy-substituted zinc phthalocyanine derivatives : synthesis, photophysical and photochemical studies
- Erdoğmuş, Ali, Nyokong, Tebello
- Authors: Erdoğmuş, Ali , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6572 , http://hdl.handle.net/10962/d1004135
- Description: The syntheses of new three phthalonitriles (1, 2 and 3), together with photophysical and photochemical properties of the resulting peripherally and non-peripherally tetrakis- and octakis 3,4-(methylendioxy)-phenoxy-substituted zinc phthalocyanines (4, 5 and 6) are described for the first time. Complexes 4, 5 and 6 have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. Complexes 4, 5 and 6 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are mainly not aggregated (except for complex 6 in DMSO) within a wide concentration range. General trends are described for singlet oxygen, photodegradation, fluorescence quantum yields, triplet quantum yields and triplet life times of these complexes in DMSO and toluene. Complex 4 has higher singlet oxygen quantum yields, fluorescence quantum yields, triplet quantum yields and triplet life times than complexes 5 and 6. The effect of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (4, 5 and 6) are also reported.
- Full Text:
- Date Issued: 2009
- Authors: Erdoğmuş, Ali , Nyokong, Tebello
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6572 , http://hdl.handle.net/10962/d1004135
- Description: The syntheses of new three phthalonitriles (1, 2 and 3), together with photophysical and photochemical properties of the resulting peripherally and non-peripherally tetrakis- and octakis 3,4-(methylendioxy)-phenoxy-substituted zinc phthalocyanines (4, 5 and 6) are described for the first time. Complexes 4, 5 and 6 have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. Complexes 4, 5 and 6 have good solubility in organic solvents such as CHCl3, DCM, DMSO, DMF, THF and toluene and are mainly not aggregated (except for complex 6 in DMSO) within a wide concentration range. General trends are described for singlet oxygen, photodegradation, fluorescence quantum yields, triplet quantum yields and triplet life times of these complexes in DMSO and toluene. Complex 4 has higher singlet oxygen quantum yields, fluorescence quantum yields, triplet quantum yields and triplet life times than complexes 5 and 6. The effect of the solvents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (4, 5 and 6) are also reported.
- Full Text:
- Date Issued: 2009
Effect of laundry activities on in-stream concentrations of linear alkylbenzene sulfonate in a small rural South African river
- Gordon, Andrew K, Muller, Wilhelmine J, Gysman, N, Marshall, S J, Sparham, C J, O'Connor, S M, Whelan, M J
- Authors: Gordon, Andrew K , Muller, Wilhelmine J , Gysman, N , Marshall, S J , Sparham, C J , O'Connor, S M , Whelan, M J
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7094 , http://hdl.handle.net/10962/d1012427
- Description: In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L− 1) but were generally very low (< 11 µg L− 1) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.
- Full Text:
- Date Issued: 2009
- Authors: Gordon, Andrew K , Muller, Wilhelmine J , Gysman, N , Marshall, S J , Sparham, C J , O'Connor, S M , Whelan, M J
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7094 , http://hdl.handle.net/10962/d1012427
- Description: In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L− 1) but were generally very low (< 11 µg L− 1) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.
- Full Text:
- Date Issued: 2009
Hydrology, sediment transport dynamics and geomorphology of a variable flow river : the Mfolozi River, South Africa
- Grenfell, Suzanne E, Ellery, William F N
- Authors: Grenfell, Suzanne E , Ellery, William F N
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6632 , http://hdl.handle.net/10962/d1006826
- Description: The co-efficient of variation for inter-annual streamflow of the Mfolozi River is extremely high at 79%. An analysis of flow frequency indicated that streamflow is skewed towards low-flow values, with a number of extremely large flood events occurring as outliers on the histogram. Streamflow variability in the Mfolozi River may be linked to multiple factors including a large catchment size, a seasonal climate of a dry winter and wet summer, evergreen vegetation in the catchment, variable precipitation and the occurrence of regionally pervasive climatic oscillations. This research aimed to address how streamflow variability impacted upon sediment transport and thus, geomorphology. It was found that sediment transport variability occurred at the intra-and inter-annual scale. Analysis of mean monthly sediment concentration and discharge showed a hysteresis effect, such that sediment concentration peaked prior to discharge in the early wet season. During the late wet season, peak discharges often had unexpectedly low sediment concentrations. Furthermore, data suggested the existence of long-term hysteresis that may be related to decadal-scale climatic oscillations that alter sediment availability and stream capacity, resulting in discharge peaking in 2000 and sediment concentration in 2005. However, more data are required to confirm this relationship. Variability in streamflow appears to share a causal relationship with sediment transport variability, as both are linked to variation in precipitation and the resultant impacts on vegetation growth and evapotranspiration rates. The variability of streamflow and sediment transport has implications for stream and floodplain geomorphology, and the hydrology of variable rivers should be considered when interpreting their geomorphology.
- Full Text:
- Date Issued: 2009
- Authors: Grenfell, Suzanne E , Ellery, William F N
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6632 , http://hdl.handle.net/10962/d1006826
- Description: The co-efficient of variation for inter-annual streamflow of the Mfolozi River is extremely high at 79%. An analysis of flow frequency indicated that streamflow is skewed towards low-flow values, with a number of extremely large flood events occurring as outliers on the histogram. Streamflow variability in the Mfolozi River may be linked to multiple factors including a large catchment size, a seasonal climate of a dry winter and wet summer, evergreen vegetation in the catchment, variable precipitation and the occurrence of regionally pervasive climatic oscillations. This research aimed to address how streamflow variability impacted upon sediment transport and thus, geomorphology. It was found that sediment transport variability occurred at the intra-and inter-annual scale. Analysis of mean monthly sediment concentration and discharge showed a hysteresis effect, such that sediment concentration peaked prior to discharge in the early wet season. During the late wet season, peak discharges often had unexpectedly low sediment concentrations. Furthermore, data suggested the existence of long-term hysteresis that may be related to decadal-scale climatic oscillations that alter sediment availability and stream capacity, resulting in discharge peaking in 2000 and sediment concentration in 2005. However, more data are required to confirm this relationship. Variability in streamflow appears to share a causal relationship with sediment transport variability, as both are linked to variation in precipitation and the resultant impacts on vegetation growth and evapotranspiration rates. The variability of streamflow and sediment transport has implications for stream and floodplain geomorphology, and the hydrology of variable rivers should be considered when interpreting their geomorphology.
- Full Text:
- Date Issued: 2009
Geomorphology and dynamics of the Mfolozi River floodplain, KwaZulu-Natal, South Africa
- Grenfell, Suzanne E, Ellery, William F N, Grenfell, Michael C
- Authors: Grenfell, Suzanne E , Ellery, William F N , Grenfell, Michael C
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6633 , http://hdl.handle.net/10962/d1006827
- Description: The geomorphology and dynamics of the Mfolozi River floodplain and estuary, located in the subtropical region of northern KwaZulu-Natal, South Africa, were considered with respect to existing models of avulsion and alluvial stratigraphy. The Mfolozi River floodplain may be divided into regions based on longitudinal slope and dominant geomorphic processes. Confinement of the Mfolozi River above the floodplain has led to the development of an alluvial fan at the floodplain head, characterized by a relatively high sedimentation rate and avulsion frequency, at a gradient of 0.10%. The lower floodplain is controlled by sea level, with an average gradient of 0.05%. Between the two lies an extremely flat region with an average gradient of 0.02%, which may be controlled by faulting of the underlying bedrock. Avulsion occurrences on the Mfolozi floodplain are linked to the two main zones of aggradation, the alluvial fan at the floodplain head, and toward the river mouth in the lower floodplain. On the alluvial fan, normal flow conditions result in scour from local steepening. During infrequent, large flood events, the channel becomes overwhelmed with sediment and stream flow, and avulses. The resulting avulsion is regional, and affects the location of the channel from the floodplain head to the river mouth. Deposits resulting from such avulsions contribute significantly to the total volume of sediment stored in the floodplain, and tend to persist for long periods after the avulsion. Contrastingly, on the lower floodplain, reaching of the avulsion threshold is not necessarily linked to large flood events, but rather to long-term aggradation on the channel that decreases the existing channels gradient while increasing its elevation above the surrounding floodplain. Resultant avulsions tend to be local and do not contribute significantly to the overall volume of floodplain alluvium.
- Full Text:
- Date Issued: 2009
- Authors: Grenfell, Suzanne E , Ellery, William F N , Grenfell, Michael C
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:6633 , http://hdl.handle.net/10962/d1006827
- Description: The geomorphology and dynamics of the Mfolozi River floodplain and estuary, located in the subtropical region of northern KwaZulu-Natal, South Africa, were considered with respect to existing models of avulsion and alluvial stratigraphy. The Mfolozi River floodplain may be divided into regions based on longitudinal slope and dominant geomorphic processes. Confinement of the Mfolozi River above the floodplain has led to the development of an alluvial fan at the floodplain head, characterized by a relatively high sedimentation rate and avulsion frequency, at a gradient of 0.10%. The lower floodplain is controlled by sea level, with an average gradient of 0.05%. Between the two lies an extremely flat region with an average gradient of 0.02%, which may be controlled by faulting of the underlying bedrock. Avulsion occurrences on the Mfolozi floodplain are linked to the two main zones of aggradation, the alluvial fan at the floodplain head, and toward the river mouth in the lower floodplain. On the alluvial fan, normal flow conditions result in scour from local steepening. During infrequent, large flood events, the channel becomes overwhelmed with sediment and stream flow, and avulses. The resulting avulsion is regional, and affects the location of the channel from the floodplain head to the river mouth. Deposits resulting from such avulsions contribute significantly to the total volume of sediment stored in the floodplain, and tend to persist for long periods after the avulsion. Contrastingly, on the lower floodplain, reaching of the avulsion threshold is not necessarily linked to large flood events, but rather to long-term aggradation on the channel that decreases the existing channels gradient while increasing its elevation above the surrounding floodplain. Resultant avulsions tend to be local and do not contribute significantly to the overall volume of floodplain alluvium.
- Full Text:
- Date Issued: 2009
A change of the seaward boundary of Goukamma Marine Protected Area could increase conservation and fishery benefits
- Götz, Albrecht, Kerwath, S E, Attwood, Colin G
- Authors: Götz, Albrecht , Kerwath, S E , Attwood, Colin G
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:7147 , http://hdl.handle.net/10962/d1011846 , https://doi.org/10.4102/sajs.v105i9/10.102
- Description: Goukamma Marine Protected Area (MPA) on the South African temperate South Coast has been shown to be effective in maintaining a spawning stock of roman, Chrysoblephus laticeps (Sparidae). The larval ecology and the oceanographic conditions in the area suggest a good potential for the enhancement of roman stocks outside the reserve through larval dispersal. A high rate of illegal fishing just inside the seaward boundary of the MPA could severely compromise its function.We suggest that a change of the seaward boundary of the reserve to coincide with a latitudinal line could increase its function as a harvest refuge for resident reef fishes such as roman, facilitate voluntary compliance and monitoring and prosecution of illegal fishing without a significant negative impact on the commercial linefishing fleet in the area. Simple adjustments such as the one proposed here could be attempted at a number of South African MPAs as they would be beneficial to achieve fishery and conservation goals alike.
- Full Text:
- Date Issued: 2009
- Authors: Götz, Albrecht , Kerwath, S E , Attwood, Colin G
- Date: 2009
- Language: English
- Type: Article
- Identifier: vital:7147 , http://hdl.handle.net/10962/d1011846 , https://doi.org/10.4102/sajs.v105i9/10.102
- Description: Goukamma Marine Protected Area (MPA) on the South African temperate South Coast has been shown to be effective in maintaining a spawning stock of roman, Chrysoblephus laticeps (Sparidae). The larval ecology and the oceanographic conditions in the area suggest a good potential for the enhancement of roman stocks outside the reserve through larval dispersal. A high rate of illegal fishing just inside the seaward boundary of the MPA could severely compromise its function.We suggest that a change of the seaward boundary of the reserve to coincide with a latitudinal line could increase its function as a harvest refuge for resident reef fishes such as roman, facilitate voluntary compliance and monitoring and prosecution of illegal fishing without a significant negative impact on the commercial linefishing fleet in the area. Simple adjustments such as the one proposed here could be attempted at a number of South African MPAs as they would be beneficial to achieve fishery and conservation goals alike.
- Full Text:
- Date Issued: 2009
Towards a GPS-based TEC prediction model for Southern Africa with feed forward networks
- Habarulema, John B, McKinnell, Lee-Anne, Opperman, Ben D L
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6806 , http://hdl.handle.net/10962/d1004192
- Description: In this paper, first results from a national Global Positioning System (GPS) based total electron content (TEC) prediction model over South Africa are presented. Data for 10 GPS receiver stations distributed through out the country were used to train a feed forward neural network (NN) over an interval of at most five years. In the NN training, validating and testing processes, five factors which are well known to influence TEC variability namely diurnal variation, seasonal variation, magnetic activity, solar activity and the geographic position of the GPS receivers were included in the NN model. The database consisted of 1-min data and therefore the NN model developed can be used to forecast TEC values 1 min in advance. Results from the NN national model (NM) were compared with hourly TEC values generated by the earlier developed NN single station models (SSMs) at Sutherland (32.38°S, 20.81°E) and Springbok (29.67°S, 17.88°E), to predict TEC variations over the Cape Town (33.95°S, 18.47°E) and Upington (28.41°S, 21.26°E) stations, respectively, during equinoxes and solstices. This revealed that, on average, the NM led to an improvement in TEC prediction accuracy compared to the SSMs for the considered testing periods.
- Full Text:
- Date Issued: 2009
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6806 , http://hdl.handle.net/10962/d1004192
- Description: In this paper, first results from a national Global Positioning System (GPS) based total electron content (TEC) prediction model over South Africa are presented. Data for 10 GPS receiver stations distributed through out the country were used to train a feed forward neural network (NN) over an interval of at most five years. In the NN training, validating and testing processes, five factors which are well known to influence TEC variability namely diurnal variation, seasonal variation, magnetic activity, solar activity and the geographic position of the GPS receivers were included in the NN model. The database consisted of 1-min data and therefore the NN model developed can be used to forecast TEC values 1 min in advance. Results from the NN national model (NM) were compared with hourly TEC values generated by the earlier developed NN single station models (SSMs) at Sutherland (32.38°S, 20.81°E) and Springbok (29.67°S, 17.88°E), to predict TEC variations over the Cape Town (33.95°S, 18.47°E) and Upington (28.41°S, 21.26°E) stations, respectively, during equinoxes and solstices. This revealed that, on average, the NM led to an improvement in TEC prediction accuracy compared to the SSMs for the considered testing periods.
- Full Text:
- Date Issued: 2009