Parallel packet classification using GPU co-processors
- Nottingham, Alistair, Irwin, Barry V W
- Authors: Nottingham, Alistair , Irwin, Barry V W
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430250 , vital:72677 , https://doi.org/10.1145/1899503.1899529
- Description: In the domain of network security, packet filtering for classification pur-poses is of significant interest. Packet classification provides a mecha-nism for understanding the composition of packet streams arriving at distinct network interfaces, and is useful in diagnosing threats and un-covering vulnerabilities so as to maximise data integrity and system se-curity. Traditional packet classifiers, such as PCAP, have utilised Con-trol Flow Graphs (CFGs) in representing filter sets, due to both their amenability to optimisation, and their inherent structural applicability to the metaphor of decision-based classification. Unfortunately, CFGs do not map well to cooperative processing implementations, and single-threaded CPU-based implementations have proven too slow for real-time classification against multiple arbitrary filters on next generation networks. In this paper, we consider a novel multithreaded classification algorithm, optimised for execution on GPU co-processors, intended to accelerate classification throughput and maximise processing efficien-cy in a highly parallel execution context.
- Full Text:
- Date Issued: 2010
- Authors: Nottingham, Alistair , Irwin, Barry V W
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/430250 , vital:72677 , https://doi.org/10.1145/1899503.1899529
- Description: In the domain of network security, packet filtering for classification pur-poses is of significant interest. Packet classification provides a mecha-nism for understanding the composition of packet streams arriving at distinct network interfaces, and is useful in diagnosing threats and un-covering vulnerabilities so as to maximise data integrity and system se-curity. Traditional packet classifiers, such as PCAP, have utilised Con-trol Flow Graphs (CFGs) in representing filter sets, due to both their amenability to optimisation, and their inherent structural applicability to the metaphor of decision-based classification. Unfortunately, CFGs do not map well to cooperative processing implementations, and single-threaded CPU-based implementations have proven too slow for real-time classification against multiple arbitrary filters on next generation networks. In this paper, we consider a novel multithreaded classification algorithm, optimised for execution on GPU co-processors, intended to accelerate classification throughput and maximise processing efficien-cy in a highly parallel execution context.
- Full Text:
- Date Issued: 2010
Philosophers and the Poor
- Authors: Jones, Ward E
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275671 , vital:55068 , xlink:href="https://doi.org/10.3167/th.2010.5712506"
- Description: This is a programmatic paper, calling for the renewal andmodernisation of the therapeutic approach to philosophy found inEpicureans, Stoics, and Skeptics; and, in particular, for an applicationof the therapeutic approach to the life of poverty. The general assump-tion behind a therapeutic approach to philosophy is that it is possiblefor someone to be exposed to philosophical work which leads her toan improved understanding of herself and her situation, and for herlife to be improved by this understanding. After offering a sketch ofhow, given the current nature of academic philosophy, such work willbe carried out and disseminated, I suggest three areas in which philo-sophical discourse could have a therapeutic affect on the poor.
- Full Text:
- Date Issued: 2010
- Authors: Jones, Ward E
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/275671 , vital:55068 , xlink:href="https://doi.org/10.3167/th.2010.5712506"
- Description: This is a programmatic paper, calling for the renewal andmodernisation of the therapeutic approach to philosophy found inEpicureans, Stoics, and Skeptics; and, in particular, for an applicationof the therapeutic approach to the life of poverty. The general assump-tion behind a therapeutic approach to philosophy is that it is possiblefor someone to be exposed to philosophical work which leads her toan improved understanding of herself and her situation, and for herlife to be improved by this understanding. After offering a sketch ofhow, given the current nature of academic philosophy, such work willbe carried out and disseminated, I suggest three areas in which philo-sophical discourse could have a therapeutic affect on the poor.
- Full Text:
- Date Issued: 2010
Photoelectrochemical characterization of electrodeposited ZnO thin films sensitized by octacarboxymetallophthalocyanine derivatives
- Idowu, Mopelola, Loewenstein, Thomas, Hastall, Andreas, Nyokong, Tebello, Schlettwein, Derck
- Authors: Idowu, Mopelola , Loewenstein, Thomas , Hastall, Andreas , Nyokong, Tebello , Schlettwein, Derck
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262655 , vital:53541 , xlink:href="https://doi.org/10.1142/S1088424610001854"
- Description: Hybrid thin films of crystalline zinc oxide (ZnO) modified by different octacarboxymetallophthalocyanines (MOCPc) were prepared by the readsorption method. Homogeneously blue or green thin films were formed. The photoelectrochemical characteristics of the electrodes were studied by time-resolved photocurrent measurements. Zinc(II) 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine (ZnOCPc) showed considerably large quantum efficiency in sensitization of ZnO, one of the highest quantum efficiencies obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films.
- Full Text:
- Date Issued: 2010
- Authors: Idowu, Mopelola , Loewenstein, Thomas , Hastall, Andreas , Nyokong, Tebello , Schlettwein, Derck
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262655 , vital:53541 , xlink:href="https://doi.org/10.1142/S1088424610001854"
- Description: Hybrid thin films of crystalline zinc oxide (ZnO) modified by different octacarboxymetallophthalocyanines (MOCPc) were prepared by the readsorption method. Homogeneously blue or green thin films were formed. The photoelectrochemical characteristics of the electrodes were studied by time-resolved photocurrent measurements. Zinc(II) 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine (ZnOCPc) showed considerably large quantum efficiency in sensitization of ZnO, one of the highest quantum efficiencies obtained so far with phthalocyanine-type sensitizers on nanocrystalline ZnO films.
- Full Text:
- Date Issued: 2010
Photophysical and photochemical parameters of octakis (benzylthio) phthalocyaninato zinc, aluminium and tin
- Akpe, Victor, Brismar, Hjalmar, Nyokong, Tebello, Osadebe, Patience Ogoamak
- Authors: Akpe, Victor , Brismar, Hjalmar , Nyokong, Tebello , Osadebe, Patience Ogoamak
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248472 , vital:51689 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.08.033"
- Description: This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)8 (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, RsI of the complexes tend to increase as the refractive index, nD, and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, ϕd measurements of these compounds show that they are highly photostable, ϕd (0.03–0.33 × 10−5). The triplet quantum yield, ϕT (0.40–0.53) and the triplet lifetime, τT (610–810 μs) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency, SΔ, is relatively high for all the molecules (0.74–0.90).
- Full Text:
- Date Issued: 2010
- Authors: Akpe, Victor , Brismar, Hjalmar , Nyokong, Tebello , Osadebe, Patience Ogoamak
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248472 , vital:51689 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.08.033"
- Description: This paper addresses the synthesis of octa-substituted benzylthio metallophthalocyanines (OBTMPcs) that contain the central metal ions of Zn2+, Al3+ and Sn4+. The ground state absorption of ZnPc(SR)8 (OBTZnPc) along with the ZnPc derivatives, well documented in literature were used to study a new concept called the red shift index (RsI). The concept is based on the empirical values of RsI of the different complexes in solvent media. Unequivocally, parameters used in this paper show strong correlations that are consistent with the results obtained. For instance, RsI of the complexes tend to increase as the refractive index, nD, and solvent donor, DN, of solvent increases. Photodegradation (photobleaching) quantum yield, ϕd measurements of these compounds show that they are highly photostable, ϕd (0.03–0.33 × 10−5). The triplet quantum yield, ϕT (0.40–0.53) and the triplet lifetime, τT (610–810 μs) are within the typical range for metallophthalocyanines in DMSO. The photosensitisation efficiency, SΔ, is relatively high for all the molecules (0.74–0.90).
- Full Text:
- Date Issued: 2010
Photophysical and photochemical properties of Ni (II), Pd (II) and Pt (II) aryloxo and alkylthio derivatised phthalocyanine
- Ogunbayo, Taofeek B, Nyokong, Tebello
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261511 , vital:53416 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.03.047"
- Description: Several aryloxo (3a–6a and 3b–6b) and alkylthio (3d and 3e) derivatised phthalocyanines were synthesized, characterized and the photochemical and photophysical properties investigated along with those of the previously reported (3c–5c, 4d, 5d, 4e and 5e) complexes. The effects of open-shell metals (Ni(II), Pd(II) and Pt(II)) on the photophysical and photochemical properties of the phthalocyanine ligands were investigated. Palladium and platinum improved the triplet quantum yield and singlet oxygen generation capacities of the unmetalated phthalocyanines (3a–3e) making their complexes candidates for further investigation in photocatalysis. Ni(II)Pc analogues gave poor results compared with their Pd(II)Pc and Pt(II)Pc counterparts.
- Full Text:
- Date Issued: 2010
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261511 , vital:53416 , xlink:href="https://doi.org/10.1016/j.molstruc.2010.03.047"
- Description: Several aryloxo (3a–6a and 3b–6b) and alkylthio (3d and 3e) derivatised phthalocyanines were synthesized, characterized and the photochemical and photophysical properties investigated along with those of the previously reported (3c–5c, 4d, 5d, 4e and 5e) complexes. The effects of open-shell metals (Ni(II), Pd(II) and Pt(II)) on the photophysical and photochemical properties of the phthalocyanine ligands were investigated. Palladium and platinum improved the triplet quantum yield and singlet oxygen generation capacities of the unmetalated phthalocyanines (3a–3e) making their complexes candidates for further investigation in photocatalysis. Ni(II)Pc analogues gave poor results compared with their Pd(II)Pc and Pt(II)Pc counterparts.
- Full Text:
- Date Issued: 2010
Photophysical properties of newly synthesized fluorinated zinc phthalocyanines in the presence of CdTe quantum dots and the accompanying energy transfer processes
- Erdoğmuş, Ali, Moeno, Sharon, Litwinski, Christian, Nyokong, Tebello
- Authors: Erdoğmuş, Ali , Moeno, Sharon , Litwinski, Christian , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262671 , vital:53543 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.12.014"
- Description: The photophysical properties of two newly synthesized phthalocyanines (Pcs) were studied in the presence and the absence of 3-mercaptopropionic acid (MPA) capped quantum dots (QDs). Energy transfer processes resulting from the combination of QDs and the Pcs: 4-(tetrakis-5-(trifluoromethyl)-2-mercaptopyridinephthalocyaninato)zinc(II) (TtfmMPyZnPc, 3) and 4-(tetrakis-5-(trifluoromethyl)-2-pyridyloxyphthalocyaninato) zinc(II) (TtfmPyZnPc, 4) were also studied. The photophysical properties of the Pcs in the presence of QDs were enhanced and Förster resonance energy transfer (FRET) was observed with the phthalocyanines used. The efficiency of FRET between the QDs and TtfmMPyZnPc and TtfmPyZnPc was found to be 0.31% and 0.45% in DMSO and 0.24% and 0.32% in pyridine, respectively. The triplet state quantum yields for TtfmMPyZnPc and TtfmPyZnPc were found to be 0.86 and 0.74 in DMSO and 0.83 and 0.76 in pyridine.
- Full Text:
- Date Issued: 2010
- Authors: Erdoğmuş, Ali , Moeno, Sharon , Litwinski, Christian , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/262671 , vital:53543 , xlink:href="https://doi.org/10.1016/j.jphotochem.2009.12.014"
- Description: The photophysical properties of two newly synthesized phthalocyanines (Pcs) were studied in the presence and the absence of 3-mercaptopropionic acid (MPA) capped quantum dots (QDs). Energy transfer processes resulting from the combination of QDs and the Pcs: 4-(tetrakis-5-(trifluoromethyl)-2-mercaptopyridinephthalocyaninato)zinc(II) (TtfmMPyZnPc, 3) and 4-(tetrakis-5-(trifluoromethyl)-2-pyridyloxyphthalocyaninato) zinc(II) (TtfmPyZnPc, 4) were also studied. The photophysical properties of the Pcs in the presence of QDs were enhanced and Förster resonance energy transfer (FRET) was observed with the phthalocyanines used. The efficiency of FRET between the QDs and TtfmMPyZnPc and TtfmPyZnPc was found to be 0.31% and 0.45% in DMSO and 0.24% and 0.32% in pyridine, respectively. The triplet state quantum yields for TtfmMPyZnPc and TtfmPyZnPc were found to be 0.86 and 0.74 in DMSO and 0.83 and 0.76 in pyridine.
- Full Text:
- Date Issued: 2010
Photophysical study of a covalently linked quantum dot–low symmetry phthalocyanine conjugate
- Chidawanyika, Wadzanai J U, Litwinski, Christian, Antunes, Edith M, Nyokong, Tebello
- Authors: Chidawanyika, Wadzanai J U , Litwinski, Christian , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261641 , vital:53430 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.03.008"
- Description: The linkage of a low symmetry phthalocyanine, ZnttbIPc to mercaptopropionic acid (MPA) capped CdTe quantum dots has been achieved using a coupling agent, dicyclohexylcarbodiimide (DCC), to facilitate formation of an amide bond. UV–vis, Raman and IR spectroscopic studies on the linked (QD:ZnttbIPc-linked) conjugate suggest the reaction was a success. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnttbIPc in both the linked (QD:ZnttbIPc-linked) and mixed (QD:ZnttbIPc-mixed) conjugates. The linked complex (QD:ZnttbIPc-linked) gave the largest FRET efficiency hence showing the advantages of covalent linking. Photophysicochemical properties of the phthalocyanine were improved in the presence of the QDs i.e. for QD:ZnttbIPc-mixed. Fluorescence lifetimes of QDs were unchanged in QD:ZnttbIPc-mixed and decreased for QD:ZnttbIPc-linked.
- Full Text:
- Date Issued: 2010
- Authors: Chidawanyika, Wadzanai J U , Litwinski, Christian , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261641 , vital:53430 , xlink:href="https://doi.org/10.1016/j.jphotochem.2010.03.008"
- Description: The linkage of a low symmetry phthalocyanine, ZnttbIPc to mercaptopropionic acid (MPA) capped CdTe quantum dots has been achieved using a coupling agent, dicyclohexylcarbodiimide (DCC), to facilitate formation of an amide bond. UV–vis, Raman and IR spectroscopic studies on the linked (QD:ZnttbIPc-linked) conjugate suggest the reaction was a success. Förster resonance energy transfer (FRET) resulted in stimulated emission of ZnttbIPc in both the linked (QD:ZnttbIPc-linked) and mixed (QD:ZnttbIPc-mixed) conjugates. The linked complex (QD:ZnttbIPc-linked) gave the largest FRET efficiency hence showing the advantages of covalent linking. Photophysicochemical properties of the phthalocyanine were improved in the presence of the QDs i.e. for QD:ZnttbIPc-mixed. Fluorescence lifetimes of QDs were unchanged in QD:ZnttbIPc-mixed and decreased for QD:ZnttbIPc-linked.
- Full Text:
- Date Issued: 2010
Population structure and growth of polydorid polychaetes that infest cultured abalone Haliotis midae
- Simon, Carol A, Booth, Anthony J
- Authors: Simon, Carol A , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125731 , vital:35812 , https://doi.10.2989/AJMS.2007.29.3.16.346
- Description: Polydorid polychaetes can infest cultured abalone thereby reducing productivity. In order to effectively control these pests, their reproductive biology must be understood. The population dynamics and reproduction of polydorids infesting abalone Haliotis midae from two farms in South Africa is described using a length-based, age-structured model. Shells were infested mainly by introduced Boccardia proboscidea. Polydora hoplura and Dipolydora capensis were also present but in numbers too few to identify factors influencing infestation. At both farms, B. proboscidea lived for a minimum of 12 months. Growth rate, size at maturity, maximum size, infestation intensity, recruitment, percentage of the population brooding and mortality appear to be affected by abalone feeding regime and water temperature, and these factors need to be considered in controlling infestation. Brooders and recruits were present throughout the year, but increased significantly during mid- to late winter/early spring when water temperature and day length increased. Treatment measures should therefore be implemented throughout the year but with increased effort when water temperature increases.
- Full Text:
- Date Issued: 2010
Population structure and growth of polydorid polychaetes that infest cultured abalone Haliotis midae
- Authors: Simon, Carol A , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125731 , vital:35812 , https://doi.10.2989/AJMS.2007.29.3.16.346
- Description: Polydorid polychaetes can infest cultured abalone thereby reducing productivity. In order to effectively control these pests, their reproductive biology must be understood. The population dynamics and reproduction of polydorids infesting abalone Haliotis midae from two farms in South Africa is described using a length-based, age-structured model. Shells were infested mainly by introduced Boccardia proboscidea. Polydora hoplura and Dipolydora capensis were also present but in numbers too few to identify factors influencing infestation. At both farms, B. proboscidea lived for a minimum of 12 months. Growth rate, size at maturity, maximum size, infestation intensity, recruitment, percentage of the population brooding and mortality appear to be affected by abalone feeding regime and water temperature, and these factors need to be considered in controlling infestation. Brooders and recruits were present throughout the year, but increased significantly during mid- to late winter/early spring when water temperature and day length increased. Treatment measures should therefore be implemented throughout the year but with increased effort when water temperature increases.
- Full Text:
- Date Issued: 2010
Probing electrochemical and electrocatalytic properties of cobalt (II) and manganese (III) octakis (hexylthio) phthalocyanine as self-assembled monolayers
- Mashazi, Philani N, Antunes, Edith M, Nyokong, Tebello
- Authors: Mashazi, Philani N , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249115 , vital:51779 , xlink:href="https://doi.org/10.1142/S108842461000277X"
- Description: New peripherally (β) and non-peripherally (α) substituted metal octakis(hexylthio)phthalocyanines (β- and α-MOcHexTPc) containing cobalt and manganese as metal centers were synthesized. Their characterization using electrochemical methods showed that these complexes exhibit several redox processes at E1/2 (mV vs. Ag∣AgCl) = 380 (212) (I), 1140 (864) (II), -450 (-460) (III) and -1170 (-1304) (IV) for β- (α-) CoOcHexTPc. These redox processes were assigned to CoIIIPc-2/CoIIPc-2 (I), CoIIIPc-1/CoIIIPc-2 (II), CoIIPc-2/CoIPc-2 (III) and CoIPc-2/CoIPc-3 (IV) using spectroelectrochemistry. For the β- (α-) MnOcHexTPc complex the redox processes were observed at E1/2 (mV vs. Ag∣AgCl) = -20 (5) (I), -530 (-640) (II) and -1270 (-1380) (III) and were assigned to MnIIIPc-2/MnIIPc-2 (I), MnIIPc-2/MnIIPc-3 (II) and MnIIPc-3/MnIIPc-4 (III). Electrochemical and microscopic characterization using AFM showed that the self-assembled monolayers (SAMs) are formed on the gold surface using these complexes. The electrochemical characterization showed the blocking of the Faradaic processes at SAMs modified electrodes and these reactions are well-known to easily occur at unmodified gold electrodes. The AFM characterization showed an increase in surface roughness upon modifying the gold surface with MOcHexTPc SAMs, further confirming the presence of the monolayers on the gold surface. The MOcHexTPc SAMs were investigated for their electrocatalytic application towards H2O2 detection. The MOcHexTPc SAMs modified gold electrodes gave excellent currents for H2O2 detection. The observed H2O2 electrocatalytic reduction peaks were close to where the metal redox processes from the MOcHexTPc occurred, showing the involvement of the metal redox processes in the electrocatalytic mediation reactions.
- Full Text:
- Date Issued: 2010
- Authors: Mashazi, Philani N , Antunes, Edith M , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/249115 , vital:51779 , xlink:href="https://doi.org/10.1142/S108842461000277X"
- Description: New peripherally (β) and non-peripherally (α) substituted metal octakis(hexylthio)phthalocyanines (β- and α-MOcHexTPc) containing cobalt and manganese as metal centers were synthesized. Their characterization using electrochemical methods showed that these complexes exhibit several redox processes at E1/2 (mV vs. Ag∣AgCl) = 380 (212) (I), 1140 (864) (II), -450 (-460) (III) and -1170 (-1304) (IV) for β- (α-) CoOcHexTPc. These redox processes were assigned to CoIIIPc-2/CoIIPc-2 (I), CoIIIPc-1/CoIIIPc-2 (II), CoIIPc-2/CoIPc-2 (III) and CoIPc-2/CoIPc-3 (IV) using spectroelectrochemistry. For the β- (α-) MnOcHexTPc complex the redox processes were observed at E1/2 (mV vs. Ag∣AgCl) = -20 (5) (I), -530 (-640) (II) and -1270 (-1380) (III) and were assigned to MnIIIPc-2/MnIIPc-2 (I), MnIIPc-2/MnIIPc-3 (II) and MnIIPc-3/MnIIPc-4 (III). Electrochemical and microscopic characterization using AFM showed that the self-assembled monolayers (SAMs) are formed on the gold surface using these complexes. The electrochemical characterization showed the blocking of the Faradaic processes at SAMs modified electrodes and these reactions are well-known to easily occur at unmodified gold electrodes. The AFM characterization showed an increase in surface roughness upon modifying the gold surface with MOcHexTPc SAMs, further confirming the presence of the monolayers on the gold surface. The MOcHexTPc SAMs were investigated for their electrocatalytic application towards H2O2 detection. The MOcHexTPc SAMs modified gold electrodes gave excellent currents for H2O2 detection. The observed H2O2 electrocatalytic reduction peaks were close to where the metal redox processes from the MOcHexTPc occurred, showing the involvement of the metal redox processes in the electrocatalytic mediation reactions.
- Full Text:
- Date Issued: 2010
Production of and trade in African indigenous vegetables in the urban and peri-urban areas of Durban, South Africa
- Shackleton, Charlie M, Paumgartner, Fiona, Mthembu, Thami, Ernst, Lisa, Pasquini, Margaret W, Pichop, Germain
- Authors: Shackleton, Charlie M , Paumgartner, Fiona , Mthembu, Thami , Ernst, Lisa , Pasquini, Margaret W , Pichop, Germain
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181134 , vital:43701 , xlink:href="https://doi.org/10.1080/0376835X.2010.498937"
- Description: This paper reports on the farming and trade of lesser known crops, here termed African indigenous vegetables (AIVs), in the Durban metropole. Most households grow AIVs, and collect them from the wild, primarily for home consumption. Modal income from sale was approximately R30 per month per farmer, most of whom were middle-aged to elderly females, with limited education, who had been cultivating AIVs here for many years. The main constraints to greater sales were deemed to be low market demand and adverse climate. The commonest AIVs grown were pumpkin leaves, taro and amaranth. Although most farmers sold very little, there is a thriving retail trade in AIVs. Generally, retailers were females, but younger and more educated than the farmers. The majority viewed retailing as a full-time occupation. Modal income for retailers was R450 per month, but included non-AIV produce. Most of the traders thought there was insufficient market demand for AIVs.
- Full Text:
- Date Issued: 2010
- Authors: Shackleton, Charlie M , Paumgartner, Fiona , Mthembu, Thami , Ernst, Lisa , Pasquini, Margaret W , Pichop, Germain
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181134 , vital:43701 , xlink:href="https://doi.org/10.1080/0376835X.2010.498937"
- Description: This paper reports on the farming and trade of lesser known crops, here termed African indigenous vegetables (AIVs), in the Durban metropole. Most households grow AIVs, and collect them from the wild, primarily for home consumption. Modal income from sale was approximately R30 per month per farmer, most of whom were middle-aged to elderly females, with limited education, who had been cultivating AIVs here for many years. The main constraints to greater sales were deemed to be low market demand and adverse climate. The commonest AIVs grown were pumpkin leaves, taro and amaranth. Although most farmers sold very little, there is a thriving retail trade in AIVs. Generally, retailers were females, but younger and more educated than the farmers. The majority viewed retailing as a full-time occupation. Modal income for retailers was R450 per month, but included non-AIV produce. Most of the traders thought there was insufficient market demand for AIVs.
- Full Text:
- Date Issued: 2010
Promoting entrepreneurship in agriculture in the Eastern Cape:
- Antrobus, Geoffrey G, Fraser, Gavin C G
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143067 , vital:38198 , DOI: 10.1080/03031853.1994.9524779
- Description: Selected cases in developing entrepreneurship in small-scale subsistence and commercial agriculture in the Eastern Cape are examined, including the provision of marketing facilities, the training programme of the Africa Cooperative Action Trust (ACAT) in Ciskei, government sponsored irrigation projects and the farmer support programme. An attempt is made to draw general conclusions about the necessary ingredients for successful entrepreneurship and the formulation of proposals for further promoting entrepreneurship in agriculture in South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Antrobus, Geoffrey G , Fraser, Gavin C G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143067 , vital:38198 , DOI: 10.1080/03031853.1994.9524779
- Description: Selected cases in developing entrepreneurship in small-scale subsistence and commercial agriculture in the Eastern Cape are examined, including the provision of marketing facilities, the training programme of the Africa Cooperative Action Trust (ACAT) in Ciskei, government sponsored irrigation projects and the farmer support programme. An attempt is made to draw general conclusions about the necessary ingredients for successful entrepreneurship and the formulation of proposals for further promoting entrepreneurship in agriculture in South Africa.
- Full Text:
- Date Issued: 2010
Quantifying commercial catch and effort of monkfish Lophius vomerinus and L. vaillanti off Namibia
- Maartens, Lima, Booth, Anthony J
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
- Date Issued: 2010
- Authors: Maartens, Lima , Booth, Anthony J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125786 , vital:35817 , https://doi.10.2989/025776101784528999
- Description: Mark-recapture models do not distinguish how ‘‘deaths’’ accrue to marked animals in the population. If animals lose their tags, then recaptures will be fewer than expected and estimates of survival will be underestimated (Arnason and Mills, 1981; McDonald et al., 2003). Similarly, if the non-reporting rate is unknown and assumed to be negligible, as is the case in some tagging studies (e.g. Cliff et al., 1996, for white sharks Carcharodon carcharias), the probability of capture can be underestimated. The effects of both these problems, inherent in cooperative tagging programmes, lead to too few tagged fish being recovered, with a positive bias on the estimation of population size. These effects are most pronounced when capture probability is low and fewer tags are available for recapture (McDonald et al., 2003).
- Full Text:
- Date Issued: 2010
Remarkable sensitivity for detection of bisphenol A on a gold electrode modified with nickel tetraamino phthalocyanine containing Ni–O–Ni bridges
- Chauke, Vongani, Matemadombo, Fungisai, Nyokong, Tebello
- Authors: Chauke, Vongani , Matemadombo, Fungisai , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261280 , vital:53380 , xlink:href="https://doi.org/10.1016/j.jhazmat.2010.01.061"
- Description: This work reports the electrocatalysis of bisphenol A on Ni(II) tetraamino metallophthalocyanine (NiTAPc) polymer modified gold electrode containing Ni–O–Ni bridges (represented as Ni(OH)TAPc). The Ni(II)TAPc films were electro-transformed in 0.1 mol L−1 NaOH aqueous solution to form ‘O–Ni–O oxo bridges’, forming poly-n-Ni(OH)TAPc (where n is the number of polymerising scans). poly-30-Ni(OH)TAPc, poly-50-Ni(OH)TAPc, poly-70-Ni(OH)TAPc and poly-90-Ni(OH)TAPc films were investigated. The polymeric films were characterised by electrochemical impedance spectroscopy and the charge transfer resistance (RCT) values increased with film thickness. The best catalytic activity for the detection of bisphenol A was on poly-70-Ni(OH)TAPc. Electrode resistance to passivation improved with polymer thickness. The electrocatalytic behaviour of bisphenol A was compared to that of p-nitrophenol in terms of electrode passivation and regeneration. The latter was found to passivate the electrode less than the former. The poly-70-Ni(OH)TAPc modified electrode could reliably detect bisphenol A in a concentration range of 7 × 10−4 to 3 × 10−2 mol L−1 with a limit of detection of 3.68 × 10−9 mol L−1. The sensitivity was 3.26 × 10−4 A mol−1 L cm−2.
- Full Text:
- Date Issued: 2010
- Authors: Chauke, Vongani , Matemadombo, Fungisai , Nyokong, Tebello
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/261280 , vital:53380 , xlink:href="https://doi.org/10.1016/j.jhazmat.2010.01.061"
- Description: This work reports the electrocatalysis of bisphenol A on Ni(II) tetraamino metallophthalocyanine (NiTAPc) polymer modified gold electrode containing Ni–O–Ni bridges (represented as Ni(OH)TAPc). The Ni(II)TAPc films were electro-transformed in 0.1 mol L−1 NaOH aqueous solution to form ‘O–Ni–O oxo bridges’, forming poly-n-Ni(OH)TAPc (where n is the number of polymerising scans). poly-30-Ni(OH)TAPc, poly-50-Ni(OH)TAPc, poly-70-Ni(OH)TAPc and poly-90-Ni(OH)TAPc films were investigated. The polymeric films were characterised by electrochemical impedance spectroscopy and the charge transfer resistance (RCT) values increased with film thickness. The best catalytic activity for the detection of bisphenol A was on poly-70-Ni(OH)TAPc. Electrode resistance to passivation improved with polymer thickness. The electrocatalytic behaviour of bisphenol A was compared to that of p-nitrophenol in terms of electrode passivation and regeneration. The latter was found to passivate the electrode less than the former. The poly-70-Ni(OH)TAPc modified electrode could reliably detect bisphenol A in a concentration range of 7 × 10−4 to 3 × 10−2 mol L−1 with a limit of detection of 3.68 × 10−9 mol L−1. The sensitivity was 3.26 × 10−4 A mol−1 L cm−2.
- Full Text:
- Date Issued: 2010
Reproductive biology of a riverine cyprinid, Labeo umbratus (Teleostei: Cyprinidae), in small South African reservoirs
- Potts, Warren M, Booth, Anthony J, Hecht, Thomas, Andrew, Timothy G
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
- Authors: Potts, Warren M , Booth, Anthony J , Hecht, Thomas , Andrew, Timothy G
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125854 , vital:35826 , https://doi.10.2989/16085910509503849
- Description: The reproductive and recruitment characteristics of moggel, Labeo umbratus, populations were examined in four small South African reservoirs. Reproduction, characterised by an extended spawning season, high fecundity, short incubation time and rapid larval development, appears to be ideally suited to the highly variable environment of small reservoirs. Evidence suggested that L. umbratus spawns in the reservoirs. In two reservoirs where samples were conducted monthly, GSI (gonado-somatic index) was positively correlated with both water temperature and day length, whilst the CPUE (catch per unit effort) of juveniles was not related to any environmental variable. The success of moggel spawning appeared to increase when there was early spring and consistent summer rainfall.
- Full Text:
- Date Issued: 2010
Sedimentary facies and geomorphic evolution of a blocked‐valley lake: Lake Futululu, northern Kwazulu‐Natal, South Africa
- Grenfell, Suzanne E, Ellery, William F N, Grenfell, Michael C, Ramsay, Lisa F, Flügel, Tyrel J
- Authors: Grenfell, Suzanne E , Ellery, William F N , Grenfell, Michael C , Ramsay, Lisa F , Flügel, Tyrel J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126826 , vital:35928 , https://doi.10.1111/j.1365-3091.2009.01141.x
- Description: Blocked-valley lakes are formed when tributaries are impounded by the relatively rapid aggradation of a large river and its floodplain. These features are common in the landscape, and have been identified in the floodplains of the Solimo˜es-Amazon (Brazil) and Fly-Strickland Rivers (Papua New Guinea), for example, but their inaccessibility has resulted in studies being limited to remotely sensed image analysis. This paper documents the sedimentology and geomorphic evolution of a blocked-valley lake, Lake Futululu on the Mfolozi River floodplain margin, in South Africa, while also offering a context for the formation of lakes and wetlands at tributary junctions. The study combines aerial photography, elevation data from orthophotographs and field survey, and longitudinal sedimentology determined from a series of cores, which were sub-sampled for organic content and particle size analysis. Radiocarbon dating was used to gauge the rate and timing of peat accumulation. Results indicate that following the last glacial maximum, rising sea-levels caused aggradation of the Mfolozi River floodplain. By 3980 years bp, aggradation on the floodplain had impounded the Futululu drainage line, creating conditions suitable for peat formation, which has since occurred at a constant average rate of 0Æ13 cm year)1. Continued aggradation on the Mfolozi River floodplain has raised the base level of the Futululu drainage line, resulting in a series of backstepping sedimentary facies with fluvially derived sand and silt episodically prograding over lacustrine peat deposits. Blocked-valley lakes form where the trunk river has a much larger sediment load and catchment than the tributary stream. Similarly, when the relative difference in sediment loads is less, palustrine wetlands, rather than lakes, may be the result. In contrast, where tributaries drain a steep, well-connected catchment, they may impound much larger trunk rivers, creating lakes or wetlands upstream.
- Full Text:
- Date Issued: 2010
- Authors: Grenfell, Suzanne E , Ellery, William F N , Grenfell, Michael C , Ramsay, Lisa F , Flügel, Tyrel J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126826 , vital:35928 , https://doi.10.1111/j.1365-3091.2009.01141.x
- Description: Blocked-valley lakes are formed when tributaries are impounded by the relatively rapid aggradation of a large river and its floodplain. These features are common in the landscape, and have been identified in the floodplains of the Solimo˜es-Amazon (Brazil) and Fly-Strickland Rivers (Papua New Guinea), for example, but their inaccessibility has resulted in studies being limited to remotely sensed image analysis. This paper documents the sedimentology and geomorphic evolution of a blocked-valley lake, Lake Futululu on the Mfolozi River floodplain margin, in South Africa, while also offering a context for the formation of lakes and wetlands at tributary junctions. The study combines aerial photography, elevation data from orthophotographs and field survey, and longitudinal sedimentology determined from a series of cores, which were sub-sampled for organic content and particle size analysis. Radiocarbon dating was used to gauge the rate and timing of peat accumulation. Results indicate that following the last glacial maximum, rising sea-levels caused aggradation of the Mfolozi River floodplain. By 3980 years bp, aggradation on the floodplain had impounded the Futululu drainage line, creating conditions suitable for peat formation, which has since occurred at a constant average rate of 0Æ13 cm year)1. Continued aggradation on the Mfolozi River floodplain has raised the base level of the Futululu drainage line, resulting in a series of backstepping sedimentary facies with fluvially derived sand and silt episodically prograding over lacustrine peat deposits. Blocked-valley lakes form where the trunk river has a much larger sediment load and catchment than the tributary stream. Similarly, when the relative difference in sediment loads is less, palustrine wetlands, rather than lakes, may be the result. In contrast, where tributaries drain a steep, well-connected catchment, they may impound much larger trunk rivers, creating lakes or wetlands upstream.
- Full Text:
- Date Issued: 2010
Semi-submersible rigs: a vector transporting entire marine communities around the world
- Wanless, Ross M, Scott, Sue, Sauer, Warwick H H, Andrew, Timothy G, Glass, James P, Godfrey, Brian, Griffiths, Charles, Yeld, Eleanor
- Authors: Wanless, Ross M , Scott, Sue , Sauer, Warwick H H , Andrew, Timothy G , Glass, James P , Godfrey, Brian , Griffiths, Charles , Yeld, Eleanor
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126920 , vital:35935 , https://doi.10.1007/s10530-009-9666-2
- Description: A virtually intact subtropical reef community (14 phyla, 40 families and 62 non-native taxa) was associated with a rig under tow from Brazil that became stranded on the remote island of Tristan da Cunha. This exposes rigs as a significant vector spreading alien marine organisms, and includes the first records of free-swimming marine finfish populations becoming established after unintentional movement. With relatively trivial effort, a pre-tow clean would have obviated the need to salvage and dispose of the rig (undertaken largely to address concerns about invasive species), at a cost of *US$20 million. Our findings show that towing biofouled structures across biogeographic boundaries present unexcelled opportunities for invasion to a wide diversity of marine species. Better control and management of this vector is required urgently. Simultaneous, unintentional introductions of viable populations of multiple marine organisms are rare events, and we develop a basic framework for rapid assessment of invasion risks.
- Full Text:
- Date Issued: 2010
- Authors: Wanless, Ross M , Scott, Sue , Sauer, Warwick H H , Andrew, Timothy G , Glass, James P , Godfrey, Brian , Griffiths, Charles , Yeld, Eleanor
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126920 , vital:35935 , https://doi.10.1007/s10530-009-9666-2
- Description: A virtually intact subtropical reef community (14 phyla, 40 families and 62 non-native taxa) was associated with a rig under tow from Brazil that became stranded on the remote island of Tristan da Cunha. This exposes rigs as a significant vector spreading alien marine organisms, and includes the first records of free-swimming marine finfish populations becoming established after unintentional movement. With relatively trivial effort, a pre-tow clean would have obviated the need to salvage and dispose of the rig (undertaken largely to address concerns about invasive species), at a cost of *US$20 million. Our findings show that towing biofouled structures across biogeographic boundaries present unexcelled opportunities for invasion to a wide diversity of marine species. Better control and management of this vector is required urgently. Simultaneous, unintentional introductions of viable populations of multiple marine organisms are rare events, and we develop a basic framework for rapid assessment of invasion risks.
- Full Text:
- Date Issued: 2010
Shark fishing effort and catch of the ragged-tooth shark Carcharias taurus in the South African competitive shore-angling fishery
- Dicken, Matthew L, Booth, Anthony J, Smale, Malcolm J
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126944 , vital:35937 , https://doi.10.2989/18142320609504209
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126944 , vital:35937 , https://doi.10.2989/18142320609504209
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
Site of struggle: the Freedom Park fracas and the divisive legacy of South Africa’s Border War/Liberation Struggle
- Authors: Baines, Gary F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126954 , vital:35938 , https://doi.10.1080/02533950903076428
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
- Authors: Baines, Gary F
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126954 , vital:35938 , https://doi.10.1080/02533950903076428
- Description: In South Africa, Carcharias taurus is commonly known as the ragged-tooth shark or raggie. The species is also referred to as the sand-tiger shark in North America and as the grey-nurse shark in Australia. It is a long-lived species with an estimated longevity of up to 40 years (Goldman 2002). Female sharks reach sexual maturity at approximately 10 years (Goldman 2002), and they exhibit a biennial reproductive cycle (Branstetter and Musick 1994, Lucifora et al. 2002, G Cliff, Natal Sharks Board, unpublished data). Intra-uterine cannibalisation results in a maximum fecundity of two pups per litter after a gestation period of approximately 9–12 months (Bass et al. 1975, Gilmore et al. 1983). These life-history characteristics make this species particularly susceptible to overexploitation.
- Full Text:
- Date Issued: 2010
Social learning processes and nature-culture relations of commercial beekeeping practices as small and medium enterprise development in Zimbabwe
- Authors: Masara, Christopher
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386545 , vital:68150 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122860"
- Description: This paper explores social learning processes and nature-culture relations in a context of transition from traditional to commercial beekeeping in Zimbabwe. The contours of social learning provided by Wals (2007) are used to probe the learning processes in the social interactions shaping an emerging community of commercial beekeepers and their small and medium enterprise development practices. The paper illustrates how the practice of engaging communities in participatory expansive learning research could benefit from more refined tools for understanding the open-ended contours of social learning interactions in relation to nature-culture relations.
- Full Text:
- Date Issued: 2010
- Authors: Masara, Christopher
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386545 , vital:68150 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122860"
- Description: This paper explores social learning processes and nature-culture relations in a context of transition from traditional to commercial beekeeping in Zimbabwe. The contours of social learning provided by Wals (2007) are used to probe the learning processes in the social interactions shaping an emerging community of commercial beekeepers and their small and medium enterprise development practices. The paper illustrates how the practice of engaging communities in participatory expansive learning research could benefit from more refined tools for understanding the open-ended contours of social learning interactions in relation to nature-culture relations.
- Full Text:
- Date Issued: 2010
Spatial and seasonal distribution patterns of the ragged-tooth shark Carcharias taurus along the coast of South Africa
- Dicken, Matthew L, Booth, Anthony J, Smale, Malcolm J
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127008 , vital:35943 , https://doi.10.2989/18142320609504210
- Description: Off South Africa, the ragged-tooth shark Carcharias Taurus has been occasionally reported from the West Coast, but it is more commonly found along the East and South coasts from Cape Town to northern KwaZulu-Natal (KZN) (Bass et al. 1975, Smale 2002). Mating is thought to occur off the south coast of KZN from October to late November (G Cliff, Natal Sharks Board, unpublished data). Pregnant females then move northward to spend the early part of their gestation in the warmer waters of northern KZN and possibly southern Moçambique. During July and August, the near-term pregnant females begin to move southwards towards the cooler waters of the Eastern Cape (Wallett 1973, Bass et al. 1975, G Cliff, unpublished data), where they give birth from September to November (Smale 2002). After parturition, many of the females migrate back to KZN. The whereabouts of mature males outside of the mating season is unclear. These broadscale distribution and migratory habits for C. taurus have been inferred from limited catch records obtained for only parts of its range along the South African coast.
- Full Text:
- Date Issued: 2010
- Authors: Dicken, Matthew L , Booth, Anthony J , Smale, Malcolm J
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/127008 , vital:35943 , https://doi.10.2989/18142320609504210
- Description: Off South Africa, the ragged-tooth shark Carcharias Taurus has been occasionally reported from the West Coast, but it is more commonly found along the East and South coasts from Cape Town to northern KwaZulu-Natal (KZN) (Bass et al. 1975, Smale 2002). Mating is thought to occur off the south coast of KZN from October to late November (G Cliff, Natal Sharks Board, unpublished data). Pregnant females then move northward to spend the early part of their gestation in the warmer waters of northern KZN and possibly southern Moçambique. During July and August, the near-term pregnant females begin to move southwards towards the cooler waters of the Eastern Cape (Wallett 1973, Bass et al. 1975, G Cliff, unpublished data), where they give birth from September to November (Smale 2002). After parturition, many of the females migrate back to KZN. The whereabouts of mature males outside of the mating season is unclear. These broadscale distribution and migratory habits for C. taurus have been inferred from limited catch records obtained for only parts of its range along the South African coast.
- Full Text:
- Date Issued: 2010