The optical limiting of blue and green ytterbium double-decker phthalocyanines in solution and in poly (acrylic acid) as thin films
- Sekhosana, Kutloana E, Nyokong, Tebello
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188585 , vital:44767 , xlink:href="https://doi.org/10.1016/j.ica.2016.05.026"
- Description: Bis{1(4), 8(11), 15(18), 22(25)-tetra(4-tert-butylphenoxy)phthalocyaninato} ytterbium(III) (2a) (the green form) was synthesized and reduced to form 2b (the blue form). Nonlinear optical parameters for complex 2 in green and blue forms were determined using the Z-scan technique and the values of third-order imaginary susceptibility (Im[χ(3)]) and second-order hyperpolarizability (γ) of the order of 10−9 (for 2b) and 10−27 esu, respectively, were obtained in solution. In poly(acrylic acid) as a thin film, complex 2a showed extremely high Im[χ(3)] and γ values of the order 10−8 and 10−25 respectively. A low optical limiting threshold value of 0.075 J cm−2 was obtained for the thin film 2a.
- Full Text:
- Date Issued: 2016
- Authors: Sekhosana, Kutloana E , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188585 , vital:44767 , xlink:href="https://doi.org/10.1016/j.ica.2016.05.026"
- Description: Bis{1(4), 8(11), 15(18), 22(25)-tetra(4-tert-butylphenoxy)phthalocyaninato} ytterbium(III) (2a) (the green form) was synthesized and reduced to form 2b (the blue form). Nonlinear optical parameters for complex 2 in green and blue forms were determined using the Z-scan technique and the values of third-order imaginary susceptibility (Im[χ(3)]) and second-order hyperpolarizability (γ) of the order of 10−9 (for 2b) and 10−27 esu, respectively, were obtained in solution. In poly(acrylic acid) as a thin film, complex 2a showed extremely high Im[χ(3)] and γ values of the order 10−8 and 10−25 respectively. A low optical limiting threshold value of 0.075 J cm−2 was obtained for the thin film 2a.
- Full Text:
- Date Issued: 2016
The pattern-richness of graphical passwords
- Vorster, Johannes, Van Heerden, Renier, Irwin, Barry V W
- Authors: Vorster, Johannes , Van Heerden, Renier , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68322 , vital:29238 , https://doi.org/10.1109/ISSA.2016.7802931
- Description: Publisher version , Conventional (text-based) passwords have shown patterns such as variations on the username, or known passwords such as “password”, “admin” or “12345”. Patterns may similarly be detected in the use of Graphical passwords (GPs). The most significant such pattern - reported by many researchers - is hotspot clustering. This paper qualitatively analyses more than 200 graphical passwords for patterns other than the classically reported hotspots. The qualitative analysis finds that a significant percentage of passwords fall into a small set of patterns; patterns that can be used to form attack models against GPs. In counter action, these patterns can also be used to educate users so that future password selection is more secure. It is the hope that the outcome from this research will lead to improved behaviour and an enhancement in graphical password security.
- Full Text: false
- Date Issued: 2016
- Authors: Vorster, Johannes , Van Heerden, Renier , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68322 , vital:29238 , https://doi.org/10.1109/ISSA.2016.7802931
- Description: Publisher version , Conventional (text-based) passwords have shown patterns such as variations on the username, or known passwords such as “password”, “admin” or “12345”. Patterns may similarly be detected in the use of Graphical passwords (GPs). The most significant such pattern - reported by many researchers - is hotspot clustering. This paper qualitatively analyses more than 200 graphical passwords for patterns other than the classically reported hotspots. The qualitative analysis finds that a significant percentage of passwords fall into a small set of patterns; patterns that can be used to form attack models against GPs. In counter action, these patterns can also be used to educate users so that future password selection is more secure. It is the hope that the outcome from this research will lead to improved behaviour and an enhancement in graphical password security.
- Full Text: false
- Date Issued: 2016
The photobleaching of the free and encapsulated metallic phthalocyanine and its effect on the photooxidation of simple molecules
- Fanchiotti, Brenda Gomes, Machado, Marcella Piffer Zamprogno, de Paula, Letícia Camilato, Durmuş, Mahmut, Nyokong, Tebello, da Silva, Gonçalves, da Silva, André Romero
- Authors: Fanchiotti, Brenda Gomes , Machado, Marcella Piffer Zamprogno , de Paula, Letícia Camilato , Durmuş, Mahmut , Nyokong, Tebello , da Silva, Gonçalves , da Silva, André Romero
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239687 , vital:50755 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2016.10.007"
- Description: The photobleaching of an unsubstituted phthalocyanine (gallium(III) phthalocyanine chloride (GaPc)) and a substituted phthalocyanine (1,4-(tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato) indium(III) chloride (InTBPPc)) was monitored for the free photosensitizers and for the phthalocyanines encapsulated into nanoparticles of PEGylated poly(D,L-lactide-co-glycolide) (PLGA-PEG). Phosphate-buffered solutions (PBS) and organic solutions of the free GaPc or the free InTBPPc, and suspensions of each encapsulated photosensitizer (2–15 μmol/L) were irradiated using a laser diode of 665 nm with a power of 1–104 mW and a light dose of 7.5 J/cm2. The relative absorbance (RA) of the free GaPc dissolved in 1-methyl-2-pyrrolidone (MP) decreased 8.4 times when the laser power increased from 1 mW to 104 mW. However, the free or encapsulated GaPc did not suffer the photobleaching in PBS solution. The RA values decreased 2.4 times and 22.2 times for the free InTBPPc dissolved in PBS solution and in dimethylformamide (DMF), respectively, but the encapsulated InTBPPc was only photobleached when the laser power was 104 mW at 8 μmol/L. The increase of the free GaPc concentration favored the photobleaching in MP until 8 μmol/L while the increase from 2 μmol/L to 5 μmol/L reduced the photodegradation in PBS solution. However, the photobleaching of the free InTBPPc in DMF or in PBS solution, and of each encapsulated photosensitizer was not influenced by increasing the concentration. The influence of the photobleaching on the capability of the free and encapsulated GaPc and InTBPPc to photooxidate the simple molecules was investigated monitoring the fluorescence of dimethylanthracene (DMA) and the tryptophan (Trp). Free InTBPPc was 2.0 and 1.8 times faster to photooxidate the DMA and Trp than it was the free GaPc, but the encapsulated GaPc was 3.4 times more efficient to photooxidize the Trp than it was the encapsulated InTBPPc due to the photodegradation suffered by the encapsulated InTBPPc. The participation of the singlet oxygen was confirmed with the sodium azide in the photobleaching of all free and encapsulated photosensitizer, and in the photooxidation of the DMA and Trp. The asymmetry of InTBPPc increased the solubility of the free compound, decreasing the aggregation state of the photosensitizer and favoring the photobleaching process. The encapsulation shows capability in decreasing the photobleaching of both photosensitizers but the confocal micrographs showed that the increase of the solubility favored the InTBPPc photobleaching during the acquisition of optical cross section. A novel low-symmetry A3B-type phthalocyanine annelated with a pyrazino[2,3-f]phenanthroline ring system and substituted with six solubilizing diisopropylphenoxy-groups (1) was synthesized by metalfree DBU-promoted cross-condensation of diiminoisoindolines derived from 4,5- bis(diisopropylphenoxy)phthalonitrile and pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile. The use of these particular precursors affords A3B phthalocyanine in 15% yield, while cross-condensation of the corresponding dinitriles yields only trace amounts of the target compound. Comparative studies of the A3B-type phthalocyanine and its symmetrical octa(diisopropylphenoxy)-substituted counterpart 2 reveal striking differences in the Q band regions of their UVevisible absorption (UVeVis) spectra, which could be readily rationalized through a comparison with calculated TD-DFT spectra. Since 1 can have two NH-tautomers with equivalent and non-equivalent NH-groups, and DFT calculations predict that the former tautomer is only 2.3 kcal/mol more stable than the latter one, a comprehensive analysis of 13C NMR spectra was carried out through the application of 1 He13C HMBC and HSQC techniques. It demonstrated that only the tautomer with equivalent NH-groups is present in solution.
- Full Text:
- Date Issued: 2016
- Authors: Fanchiotti, Brenda Gomes , Machado, Marcella Piffer Zamprogno , de Paula, Letícia Camilato , Durmuş, Mahmut , Nyokong, Tebello , da Silva, Gonçalves , da Silva, André Romero
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239687 , vital:50755 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2016.10.007"
- Description: The photobleaching of an unsubstituted phthalocyanine (gallium(III) phthalocyanine chloride (GaPc)) and a substituted phthalocyanine (1,4-(tetrakis[4-(benzyloxy)phenoxy]phthalocyaninato) indium(III) chloride (InTBPPc)) was monitored for the free photosensitizers and for the phthalocyanines encapsulated into nanoparticles of PEGylated poly(D,L-lactide-co-glycolide) (PLGA-PEG). Phosphate-buffered solutions (PBS) and organic solutions of the free GaPc or the free InTBPPc, and suspensions of each encapsulated photosensitizer (2–15 μmol/L) were irradiated using a laser diode of 665 nm with a power of 1–104 mW and a light dose of 7.5 J/cm2. The relative absorbance (RA) of the free GaPc dissolved in 1-methyl-2-pyrrolidone (MP) decreased 8.4 times when the laser power increased from 1 mW to 104 mW. However, the free or encapsulated GaPc did not suffer the photobleaching in PBS solution. The RA values decreased 2.4 times and 22.2 times for the free InTBPPc dissolved in PBS solution and in dimethylformamide (DMF), respectively, but the encapsulated InTBPPc was only photobleached when the laser power was 104 mW at 8 μmol/L. The increase of the free GaPc concentration favored the photobleaching in MP until 8 μmol/L while the increase from 2 μmol/L to 5 μmol/L reduced the photodegradation in PBS solution. However, the photobleaching of the free InTBPPc in DMF or in PBS solution, and of each encapsulated photosensitizer was not influenced by increasing the concentration. The influence of the photobleaching on the capability of the free and encapsulated GaPc and InTBPPc to photooxidate the simple molecules was investigated monitoring the fluorescence of dimethylanthracene (DMA) and the tryptophan (Trp). Free InTBPPc was 2.0 and 1.8 times faster to photooxidate the DMA and Trp than it was the free GaPc, but the encapsulated GaPc was 3.4 times more efficient to photooxidize the Trp than it was the encapsulated InTBPPc due to the photodegradation suffered by the encapsulated InTBPPc. The participation of the singlet oxygen was confirmed with the sodium azide in the photobleaching of all free and encapsulated photosensitizer, and in the photooxidation of the DMA and Trp. The asymmetry of InTBPPc increased the solubility of the free compound, decreasing the aggregation state of the photosensitizer and favoring the photobleaching process. The encapsulation shows capability in decreasing the photobleaching of both photosensitizers but the confocal micrographs showed that the increase of the solubility favored the InTBPPc photobleaching during the acquisition of optical cross section. A novel low-symmetry A3B-type phthalocyanine annelated with a pyrazino[2,3-f]phenanthroline ring system and substituted with six solubilizing diisopropylphenoxy-groups (1) was synthesized by metalfree DBU-promoted cross-condensation of diiminoisoindolines derived from 4,5- bis(diisopropylphenoxy)phthalonitrile and pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile. The use of these particular precursors affords A3B phthalocyanine in 15% yield, while cross-condensation of the corresponding dinitriles yields only trace amounts of the target compound. Comparative studies of the A3B-type phthalocyanine and its symmetrical octa(diisopropylphenoxy)-substituted counterpart 2 reveal striking differences in the Q band regions of their UVevisible absorption (UVeVis) spectra, which could be readily rationalized through a comparison with calculated TD-DFT spectra. Since 1 can have two NH-tautomers with equivalent and non-equivalent NH-groups, and DFT calculations predict that the former tautomer is only 2.3 kcal/mol more stable than the latter one, a comprehensive analysis of 13C NMR spectra was carried out through the application of 1 He13C HMBC and HSQC techniques. It demonstrated that only the tautomer with equivalent NH-groups is present in solution.
- Full Text:
- Date Issued: 2016
The phytogeography of Southern Mistbelt Forests of the Eastern Cape, South Africa
- Authors: Matiwane, Aviwe
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3224 , vital:20393
- Description: In the Eastern Cape, a moisture gradient (from west to east) exists along the Escarpment where patches of Southern Mistbelt Forests (SMF) occur. There is a notable profusion of plants in these forests, but the factors that drive plant species composition and abundance in these patches is poorly understood and such knowledge is critical if we are to address or mitigate the problems imposed by global change. Many of our ideas on plant community assembly are based on the premise that species differ in their environmental requirements for successful regeneration, especially when young. The aims of this study were to document the floristic diversity of poorly known patches of Southern Mistbelt Forests in the Eastern Cape and identify the environmental factors that influence plant community composition in these forest patches. Twenty six forest patches across the Eastern Cape were sampled. In each forest 400m2 circular plots were constructed. The diameter at breast height and stem counts for the tree species was taken and the % cover of the herbaceous species was recorded. General collections were also made to supplement the plot data in order to obtain a comprehensive flora for each forest patch. All sampling was done during the summer season of 2013 and 2014. Using plot data, Hierarchal Cluster Analysis and Multidimensional Scaling Analysis were done to compare similarities between patches. Plots from the same forest patch clustered which indicated that the species composition in each forest patch was unique. However, this pattern went down when only tree species were considered. Plant diversity also varied between patches; with those located in the east being generally more diverse than those in the west are. Clustering patterns in fragmented communities and differences in species diversity indicate evidence of species “nestedness”. Analysis of nestedness indicated that these forest patches were significantly nested. To identify which environmental variables might be correlated with both species diversity and nestedness, twelve environmental variables was selected for analysis using Canonical Correspondence Analysis and Principal Component Analysis. Results show that Mean Annual Precipitation, Mean Annual Potential Evapotranspiration, and percentage of Organic Matter of the soil were most strongly correlated with the patterns of diversity observed in these forest patches. Regression analysis indicated that Mean Annual Precipitation accounted for most of the variation in species diversity, especially for the herbaceous species. The herbaceous species thus show a greater sensitivity to “climate filtering” as a consequence of rainfall gradients. With the implementation of suitable monitoring programs, changes in abundance or even local extinction of these species can act as an early warning indicator of the possible long-term effects of climate change on forest communities.
- Full Text:
- Date Issued: 2016
- Authors: Matiwane, Aviwe
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3224 , vital:20393
- Description: In the Eastern Cape, a moisture gradient (from west to east) exists along the Escarpment where patches of Southern Mistbelt Forests (SMF) occur. There is a notable profusion of plants in these forests, but the factors that drive plant species composition and abundance in these patches is poorly understood and such knowledge is critical if we are to address or mitigate the problems imposed by global change. Many of our ideas on plant community assembly are based on the premise that species differ in their environmental requirements for successful regeneration, especially when young. The aims of this study were to document the floristic diversity of poorly known patches of Southern Mistbelt Forests in the Eastern Cape and identify the environmental factors that influence plant community composition in these forest patches. Twenty six forest patches across the Eastern Cape were sampled. In each forest 400m2 circular plots were constructed. The diameter at breast height and stem counts for the tree species was taken and the % cover of the herbaceous species was recorded. General collections were also made to supplement the plot data in order to obtain a comprehensive flora for each forest patch. All sampling was done during the summer season of 2013 and 2014. Using plot data, Hierarchal Cluster Analysis and Multidimensional Scaling Analysis were done to compare similarities between patches. Plots from the same forest patch clustered which indicated that the species composition in each forest patch was unique. However, this pattern went down when only tree species were considered. Plant diversity also varied between patches; with those located in the east being generally more diverse than those in the west are. Clustering patterns in fragmented communities and differences in species diversity indicate evidence of species “nestedness”. Analysis of nestedness indicated that these forest patches were significantly nested. To identify which environmental variables might be correlated with both species diversity and nestedness, twelve environmental variables was selected for analysis using Canonical Correspondence Analysis and Principal Component Analysis. Results show that Mean Annual Precipitation, Mean Annual Potential Evapotranspiration, and percentage of Organic Matter of the soil were most strongly correlated with the patterns of diversity observed in these forest patches. Regression analysis indicated that Mean Annual Precipitation accounted for most of the variation in species diversity, especially for the herbaceous species. The herbaceous species thus show a greater sensitivity to “climate filtering” as a consequence of rainfall gradients. With the implementation of suitable monitoring programs, changes in abundance or even local extinction of these species can act as an early warning indicator of the possible long-term effects of climate change on forest communities.
- Full Text:
- Date Issued: 2016
The trophic ecology of waterbirds in a small temperate estuary: a stable isotope and lipid tracer approach
- Authors: Hean, Jeffrey William
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54356 , vital:26557
- Description: Waterbirds are often overlooked as predators in aquatic ecosystems, despite the fact that waterbirds congregate in great numbers in and around waterways, notably estuaries. To fully appreciate the effect that aquatic feeding waterbird species may have on aquatic prey communities and the role that they play in estuarine food webs, stable isotopes and fatty acid profiles were employed to examine the seasonal diet of selected waterbirds in the Kowie Estuary, Eastern Cape Province, South Africa. Population counts were conducted every month for four seasons to examine the demography of waterbirds in the lower reaches of the estuary. The mean monthly energy consumption, along with dry matter intake of all waterbird species observed, were calculated and compared to similar estuaries in South Africa and elsewhere. Three duck species, one migrant sandpiper and one piscivore were selected for more detailed investigation at several temporal scales. This thesis has revealed that stable isotope analysis of waterbird tissues provides more informative data than fatty acid analysis for investigating waterbird diet and basal resource-tertiary consumer nutrient coupling. Stable δ15N and δ13C isotopes from several body tissues, in conjunction with SIAR models, were used to determine the seasonal diet of each waterbird species, while fatty acid profiles were investigated to examine the trophic transfer of fatty acids from basal resources to waterbird predators via the benthic fauna. Stable isotopes revealed that Cape Shoveller, Cape Teal and Yellow-Billed Duck shifted their diet over both long and short temporal scales, while the migratory Ruff and piscivorous Little Egret maintained a relatively consistent diet over time. Isopods, amphipods, copepods and Mysidacea were the main foods of all three duck species and the Ruff (>30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.
- Full Text:
- Date Issued: 2016
- Authors: Hean, Jeffrey William
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54356 , vital:26557
- Description: Waterbirds are often overlooked as predators in aquatic ecosystems, despite the fact that waterbirds congregate in great numbers in and around waterways, notably estuaries. To fully appreciate the effect that aquatic feeding waterbird species may have on aquatic prey communities and the role that they play in estuarine food webs, stable isotopes and fatty acid profiles were employed to examine the seasonal diet of selected waterbirds in the Kowie Estuary, Eastern Cape Province, South Africa. Population counts were conducted every month for four seasons to examine the demography of waterbirds in the lower reaches of the estuary. The mean monthly energy consumption, along with dry matter intake of all waterbird species observed, were calculated and compared to similar estuaries in South Africa and elsewhere. Three duck species, one migrant sandpiper and one piscivore were selected for more detailed investigation at several temporal scales. This thesis has revealed that stable isotope analysis of waterbird tissues provides more informative data than fatty acid analysis for investigating waterbird diet and basal resource-tertiary consumer nutrient coupling. Stable δ15N and δ13C isotopes from several body tissues, in conjunction with SIAR models, were used to determine the seasonal diet of each waterbird species, while fatty acid profiles were investigated to examine the trophic transfer of fatty acids from basal resources to waterbird predators via the benthic fauna. Stable isotopes revealed that Cape Shoveller, Cape Teal and Yellow-Billed Duck shifted their diet over both long and short temporal scales, while the migratory Ruff and piscivorous Little Egret maintained a relatively consistent diet over time. Isopods, amphipods, copepods and Mysidacea were the main foods of all three duck species and the Ruff (>30%). Little Egret fed mainly on flathead mullet throughout the year. Fatty acid analysis revealed evidence for trophic transfer of specific fatty acids from basal resources to waterbirds in the Kowie Estuary but provided little information on seasonal diet of waterbirds. Waterbirds foraging in the Kowie Estuary appeared to shift their diet to coincide with resource abundance pulses, but also displayed seasonal dietary overlap. This study highlights the role that waterbirds play in aquatic food webs. The subject requires more attention so that we can better understand all the predatory drivers on aquatic communities.
- Full Text:
- Date Issued: 2016
Thermoluminescence of kunzite: a study of kinetic processes and dosimetry characteristics
- Ogundare, F O, Alatishe, M A, Chithambo, Makaiko L, Costin, G
- Authors: Ogundare, F O , Alatishe, M A , Chithambo, Makaiko L , Costin, G
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124701 , vital:35650 , https://doi.org/10.1016/j.nimb.2016.02.059
- Description: Since the use of natural minerals for dating and dose reconstruction using luminescence techniques is well-established and always of interest, we present thermoluminescence characteristics of kunzite, a gem variety of spodumene. The chemical composition of the sample was determined using an Electron Probe MicroAnalyzer.
- Full Text: false
- Date Issued: 2016
- Authors: Ogundare, F O , Alatishe, M A , Chithambo, Makaiko L , Costin, G
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124701 , vital:35650 , https://doi.org/10.1016/j.nimb.2016.02.059
- Description: Since the use of natural minerals for dating and dose reconstruction using luminescence techniques is well-established and always of interest, we present thermoluminescence characteristics of kunzite, a gem variety of spodumene. The chemical composition of the sample was determined using an Electron Probe MicroAnalyzer.
- Full Text: false
- Date Issued: 2016
Time-resolved luminescence from quartz: an overview of contemporary developments and applications
- Chithambo, Makaiko L, Pagonis, Vasilis, Ankjærgaard, Christina
- Authors: Chithambo, Makaiko L , Pagonis, Vasilis , Ankjærgaard, Christina
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124743 , vital:35658 , https://doi.org/10.1016/j.physb.2015.10.014
- Description: Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
- Full Text: false
- Date Issued: 2016
- Authors: Chithambo, Makaiko L , Pagonis, Vasilis , Ankjærgaard, Christina
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124743 , vital:35658 , https://doi.org/10.1016/j.physb.2015.10.014
- Description: Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.
- Full Text: false
- Date Issued: 2016
Towards malicious network activity mitigation through subnet reputation analysis
- Herbert, Alan, Irwin, Barry V W
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427799 , vital:72463 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622788_Towards_Malicious_Network_Activity_Mitigation_through_Subnet_Reputation_Analysis/links/5b9a1a88458515310583fda6/Towards-Malicious-Network-Activity-Mitigation-through-Subnet-Reputation-Analysis.pdf
- Description: Analysis technologies that focus on partial packet rather than full packet analysis have shown promise in detection of malicious activity on net-works. NetFlow is one such emergent protocol that is used to log net-work flows through summarizing key features of them. These logs can then be exported to external NetFlow sinks and proper configuration can see effective bandwidth bottleneck mitigation occurring on net-works. Furthermore, each NetFlow source node is configurable with its own unique ID number. This feature enables a system that knows where a NetFlow source node ID number resides physically to say which network flows are occurring from which physical locations irre-spective of the IP addresses involved in these network flows.
- Full Text:
- Date Issued: 2016
- Authors: Herbert, Alan , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427799 , vital:72463 , https://www.researchgate.net/profile/Barry-Ir-win/publication/327622788_Towards_Malicious_Network_Activity_Mitigation_through_Subnet_Reputation_Analysis/links/5b9a1a88458515310583fda6/Towards-Malicious-Network-Activity-Mitigation-through-Subnet-Reputation-Analysis.pdf
- Description: Analysis technologies that focus on partial packet rather than full packet analysis have shown promise in detection of malicious activity on net-works. NetFlow is one such emergent protocol that is used to log net-work flows through summarizing key features of them. These logs can then be exported to external NetFlow sinks and proper configuration can see effective bandwidth bottleneck mitigation occurring on net-works. Furthermore, each NetFlow source node is configurable with its own unique ID number. This feature enables a system that knows where a NetFlow source node ID number resides physically to say which network flows are occurring from which physical locations irre-spective of the IP addresses involved in these network flows.
- Full Text:
- Date Issued: 2016
Transcription factor motif quality assessment requires systematic comparative analysis [version 2; referees: 2 approved]
- Kibet, Caleb K, Machanick, Philip
- Authors: Kibet, Caleb K , Machanick, Philip
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61169 , vital:27987 , http://dx.doi.org/10.12688/f1000research.7408.2
- Description: Transcription factor (TF) binding site prediction remains a challenge in gene regulatory research due to degeneracy and potential variability in binding sites in the genome. Dozens of algorithms designed to learn binding models (motifs) have generated many motifs available in research papers with a subset making it to databases like JASPAR, UniPROBE and Transfac. The presence of many versions of motifs from the various databases for a single TF and the lack of a standardized assessment technique makes it difficult for biologists to make an appropriate choice of binding model and for algorithm developers to benchmark, test and improve on their models. In this study, we review and evaluate the approaches in use, highlight differences and demonstrate the difficulty of defining a standardized motif assessment approach. We review scoring functions, motif length, test data and the type of performance metrics used in prior studies as some of the factors that influence the outcome of a motif assessment. We show that the scoring functions and statistics used in motif assessment influence ranking of motifs in a TF-specific manner. We also show that TF binding specificity can vary by source of genomic binding data. We also demonstrate that information content of a motif is not in isolation a measure of motif quality but is influenced by TF binding behaviour. We conclude that there is a need for an easy-to-use tool that presents all available evidence for a comparative analysis.
- Full Text:
- Date Issued: 2016
- Authors: Kibet, Caleb K , Machanick, Philip
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61169 , vital:27987 , http://dx.doi.org/10.12688/f1000research.7408.2
- Description: Transcription factor (TF) binding site prediction remains a challenge in gene regulatory research due to degeneracy and potential variability in binding sites in the genome. Dozens of algorithms designed to learn binding models (motifs) have generated many motifs available in research papers with a subset making it to databases like JASPAR, UniPROBE and Transfac. The presence of many versions of motifs from the various databases for a single TF and the lack of a standardized assessment technique makes it difficult for biologists to make an appropriate choice of binding model and for algorithm developers to benchmark, test and improve on their models. In this study, we review and evaluate the approaches in use, highlight differences and demonstrate the difficulty of defining a standardized motif assessment approach. We review scoring functions, motif length, test data and the type of performance metrics used in prior studies as some of the factors that influence the outcome of a motif assessment. We show that the scoring functions and statistics used in motif assessment influence ranking of motifs in a TF-specific manner. We also show that TF binding specificity can vary by source of genomic binding data. We also demonstrate that information content of a motif is not in isolation a measure of motif quality but is influenced by TF binding behaviour. We conclude that there is a need for an easy-to-use tool that presents all available evidence for a comparative analysis.
- Full Text:
- Date Issued: 2016
Transforming the use of tutorials through academic staff development
- Clarence, Sherran, Wolff, Karin, Winberg, Simon, Farmer, Jean-Lee, Esambe, Emmanuel
- Authors: Clarence, Sherran , Wolff, Karin , Winberg, Simon , Farmer, Jean-Lee , Esambe, Emmanuel
- Date: 2016
- Language: English
- Type: text , conference publication
- Identifier: http://hdl.handle.net/10962/66982 , vital:29008
- Full Text:
- Date Issued: 2016
- Authors: Clarence, Sherran , Wolff, Karin , Winberg, Simon , Farmer, Jean-Lee , Esambe, Emmanuel
- Date: 2016
- Language: English
- Type: text , conference publication
- Identifier: http://hdl.handle.net/10962/66982 , vital:29008
- Full Text:
- Date Issued: 2016
Trophic interactions in an austral temperate ephemeral pond inferred using stable isotope analysis
- Dalu, Tatenda, Weyl, Olaf L F, Froneman, P William, Wasserman, Ryan J
- Authors: Dalu, Tatenda , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68022 , vital:29185 , https://doi.org/10.1007/s10750-015-2533-5
- Description: Publisher version , Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.
- Full Text: false
- Date Issued: 2016
- Authors: Dalu, Tatenda , Weyl, Olaf L F , Froneman, P William , Wasserman, Ryan J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68022 , vital:29185 , https://doi.org/10.1007/s10750-015-2533-5
- Description: Publisher version , Ephemeral ponds are vulnerable aquatic habitats which are difficult to protect given their dynamic nature and sensitivity to degradation during dry periods. Little information is available on these habitats in austral regions, with almost no information on food-web structure and complexity. The study aimed to assess trophic interactions among dominant organisms in an ephemeral pond food web, and investigate the importance of autochthonous and allochthonous carbon, using 13C and 15N isotopes. Results of the investigation suggest that the food web comprised four trophic levels, with the top predators being Notonectids (Notonecta sp.) and diving beetles (Cybister tripunctatus (Olivier)). Intermediary trophic levels comprised zooplankton (daphniids and copepodids), macroinvertebrates (e.g. micronectids and molluscs) and tadpoles. Generalist feeders dominated the higher trophic levels (>3) with specialists comprising the lower trophic levels (≤3). The consumers preferred autochthonous fine particulate organic matter, epiphyton and submerged macrophyte organic matter sources over allochthonous sources. Autochthonous organic matter was transferred to the food web via zooplankton and select macroinvertebrates including Micronecta sp. and Physa sp. The food-web structure within the pond appeared to reflect the secondary stage of trophic structural complexity in the evolution of ephemeral ponds over the course of their hydro-period.
- Full Text: false
- Date Issued: 2016
Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
- Paterson, Iain D, Mangan, Rose, Downie, Douglas A, Coetzee, Julie A, Hill, Martin P, Burke, Ashley M, Downey, Paul O, Henry, Thomas J, Compton, Stephen G
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
- Authors: Paterson, Iain D , Mangan, Rose , Downie, Douglas A , Coetzee, Julie A , Hill, Martin P , Burke, Ashley M , Downey, Paul O , Henry, Thomas J , Compton, Stephen G
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424877 , vital:72191 , xlink:href="https://doi.org/10.1002/ece3.2297"
- Description: There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution.
- Full Text:
- Date Issued: 2016
Un Langage, des Visions, une Passerelle:
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146177 , vital:38502 , ISBN 9789074816496 , https://books.google.co.za/books?id=QDSdAQAACAAJanddq=Creer+en+postcolonie:+Voix+et+dissidences+belgo-congolaise+2010-2015andhl=enandsa=Xandved=0ahUKEwjts_Si_b_pAhXvShUIHWXwCd4Q6AEIJzAA
- Description: Book abstract. The authors and artists (Baloji, Toma Muteba Luntumbue, Nganji Laeh, Nina Miskina, Joëlle Sambi, Sarah Arens, Heleen Debeuckelaere, Bénédicte Kumbi ...) who contributed to the work to debate the Belgian postcolonial question and it will be punctuated by poetic and musical stops.
- Full Text:
- Date Issued: 2016
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146177 , vital:38502 , ISBN 9789074816496 , https://books.google.co.za/books?id=QDSdAQAACAAJanddq=Creer+en+postcolonie:+Voix+et+dissidences+belgo-congolaise+2010-2015andhl=enandsa=Xandved=0ahUKEwjts_Si_b_pAhXvShUIHWXwCd4Q6AEIJzAA
- Description: Book abstract. The authors and artists (Baloji, Toma Muteba Luntumbue, Nganji Laeh, Nina Miskina, Joëlle Sambi, Sarah Arens, Heleen Debeuckelaere, Bénédicte Kumbi ...) who contributed to the work to debate the Belgian postcolonial question and it will be punctuated by poetic and musical stops.
- Full Text:
- Date Issued: 2016
Unpacking Pandora’s box: Understanding and categorising ecosystem disservices for environmental management and human wellbeing
- Shackleton, Charlie M, Ruwanza, Sheunesu, Sinasson Sanni, Gisele, Bennett, S, De Lacy, Peter, Modipa, Rebone D, Mtati, Nosiseko, Sachikonye, Mwazvita T B, Thondhlana, Gladman
- Authors: Shackleton, Charlie M , Ruwanza, Sheunesu , Sinasson Sanni, Gisele , Bennett, S , De Lacy, Peter , Modipa, Rebone D , Mtati, Nosiseko , Sachikonye, Mwazvita T B , Thondhlana, Gladman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182113 , vital:43801 , xlink:href="https://doi.org/10.1007/s10021-015-9952-z"
- Description: Research into the benefits that ecosystems contribute to human wellbeing has multiplied over the last few years following from the seminal contributions of the international Millennium Ecosystem Assessment. In comparison, the fact that some ecosystem goods and services undermine or harm human wellbeing has been seriously overlooked. These negative impacts have become known as ecosystem disservices. The neglect of ecosystem disservices is problematic because investments into the management or reduction of ecosystem disservices may yield better outcomes for human wellbeing, or at a lower investment, than management of ecosystem services. Additionally, management to optimise specific ecosystem services may simultaneously exacerbate associated disservices. We posit that one reason for the neglect of ecosystem disservices from the discourse and policy debates around ecosystems and human wellbeing is because there is no widely accepted definition or typology of ecosystem disservices. Here, we briefly examine current understandings of the term ecosystem disservices and offer a definition and a working typology to help generate debate, policy and management options around ecosystem disservices. We differentiate ecosystem disservices from natural hazards and social hazards, consider some of their inherent properties and then classify them into six categories. A variety of examples are used to illustrate the different types of, and management strategies to, ecosystem disservices.
- Full Text:
- Date Issued: 2016
- Authors: Shackleton, Charlie M , Ruwanza, Sheunesu , Sinasson Sanni, Gisele , Bennett, S , De Lacy, Peter , Modipa, Rebone D , Mtati, Nosiseko , Sachikonye, Mwazvita T B , Thondhlana, Gladman
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182113 , vital:43801 , xlink:href="https://doi.org/10.1007/s10021-015-9952-z"
- Description: Research into the benefits that ecosystems contribute to human wellbeing has multiplied over the last few years following from the seminal contributions of the international Millennium Ecosystem Assessment. In comparison, the fact that some ecosystem goods and services undermine or harm human wellbeing has been seriously overlooked. These negative impacts have become known as ecosystem disservices. The neglect of ecosystem disservices is problematic because investments into the management or reduction of ecosystem disservices may yield better outcomes for human wellbeing, or at a lower investment, than management of ecosystem services. Additionally, management to optimise specific ecosystem services may simultaneously exacerbate associated disservices. We posit that one reason for the neglect of ecosystem disservices from the discourse and policy debates around ecosystems and human wellbeing is because there is no widely accepted definition or typology of ecosystem disservices. Here, we briefly examine current understandings of the term ecosystem disservices and offer a definition and a working typology to help generate debate, policy and management options around ecosystem disservices. We differentiate ecosystem disservices from natural hazards and social hazards, consider some of their inherent properties and then classify them into six categories. A variety of examples are used to illustrate the different types of, and management strategies to, ecosystem disservices.
- Full Text:
- Date Issued: 2016
Vertebrate Biostratigraphy of the Witteberg Group and the Devonian-Carboniferous boundary in South Africa
- Authors: Gess, Robert W
- Date: 2016
- Language: English
- Type: text , boook chapter
- Identifier: http://hdl.handle.net/10962/73987 , vital:30248 , https://doi.org/10.1007/978-3-319-40859-0_13
- Description: Witteberg Group rocks are Late Devonian to Early Carboniferous in age. Comparison with Laurasian sea-level curves has correlated the earliest Carboniferous Tournasian transgression, with the argillaceous Kweekvlei Formation, overlying the arenaceous Witpoort Formation. The Devonian/Carboniferous boundary is globally characterised by a Mass Extinction which extinguished the entire grade of placoderm fish and radically reduced sarcopterygian and acanthodian diversity, preluding an Early Carboniferous radiation of actinopterygians. Analysis of Cape Supergroup biostratigraphy reveals that a fauna preservationally dominated by placoderms, sharks, and gyracanthid acanthodians may be traced from the Upper Bokkeveld Group through the Wagondrift Formation (Witteberg Group) to the Witpoort Formation, wherein it displays an increased diversity of placoderms, as well as sarcopterygians. Overlying strata contain no placoderms or sarcopterygians, but present are some relict sharks and acanthodians, and an increasing abundance of actinopterygians. This congruence confirms sea-level curve based age estimates of the Witteberg Group and the position of the Devonian/Carboniferous boundary.
- Full Text: false
- Date Issued: 2016
- Authors: Gess, Robert W
- Date: 2016
- Language: English
- Type: text , boook chapter
- Identifier: http://hdl.handle.net/10962/73987 , vital:30248 , https://doi.org/10.1007/978-3-319-40859-0_13
- Description: Witteberg Group rocks are Late Devonian to Early Carboniferous in age. Comparison with Laurasian sea-level curves has correlated the earliest Carboniferous Tournasian transgression, with the argillaceous Kweekvlei Formation, overlying the arenaceous Witpoort Formation. The Devonian/Carboniferous boundary is globally characterised by a Mass Extinction which extinguished the entire grade of placoderm fish and radically reduced sarcopterygian and acanthodian diversity, preluding an Early Carboniferous radiation of actinopterygians. Analysis of Cape Supergroup biostratigraphy reveals that a fauna preservationally dominated by placoderms, sharks, and gyracanthid acanthodians may be traced from the Upper Bokkeveld Group through the Wagondrift Formation (Witteberg Group) to the Witpoort Formation, wherein it displays an increased diversity of placoderms, as well as sarcopterygians. Overlying strata contain no placoderms or sarcopterygians, but present are some relict sharks and acanthodians, and an increasing abundance of actinopterygians. This congruence confirms sea-level curve based age estimates of the Witteberg Group and the position of the Devonian/Carboniferous boundary.
- Full Text: false
- Date Issued: 2016
Visit the exotic birthplaces of transdisciplinarity
- Burt, Jane C, Cockburn, Jessica J, Fox, Helen E, Copteros, Athina
- Authors: Burt, Jane C , Cockburn, Jessica J , Fox, Helen E , Copteros, Athina
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/68442 , vital:29256 , https://doi.org/10.13140/RG.2.1.1511.7048
- Description: Publisher version , Preface: Why a new approach to science? The world we live in is very different to the world of one hundred years ago. The world has never been so populated by humans and never before have the spe-cies ‘human’ influenced and manipulated the natural world in the way in which we do now. Academics are calling it the age of the Anthropocene. In the age of the Anthropocene we face different challenges to what hu- mans faced centuries ago. As we find ourselves in this new age we have had to not only question ‘what we know’ but also ‘how we know’ and whether the ‘how we know’ is the right kind of ‘how’ for the problems that we face today. This has led to a questioning of the way in which we generate knowledge and the way in which this knowledge is used. This critique is not aimed at all knowledge generation it is mostly a frustration that has arisen out of the physical and biological sciences with the realisation that doing good science is just not enough to bring about meaningful change in the world. Trans-disciplinary scientists and practitioners have begun this journey in search of a new kind of science - A science in service of society! This tourist trip will re- trace the few first steps of these emerging ideas so that we can understand where these new ideas have come from and how they may influence our own research. , This document was developed for a postgraduate course on Transdisciplinary research held at Rhodes University. It explores three key theoretical approaches to transdisciplinarity in relation to the question 'Why TD?'.
- Full Text:
- Date Issued: 2016
- Authors: Burt, Jane C , Cockburn, Jessica J , Fox, Helen E , Copteros, Athina
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/68442 , vital:29256 , https://doi.org/10.13140/RG.2.1.1511.7048
- Description: Publisher version , Preface: Why a new approach to science? The world we live in is very different to the world of one hundred years ago. The world has never been so populated by humans and never before have the spe-cies ‘human’ influenced and manipulated the natural world in the way in which we do now. Academics are calling it the age of the Anthropocene. In the age of the Anthropocene we face different challenges to what hu- mans faced centuries ago. As we find ourselves in this new age we have had to not only question ‘what we know’ but also ‘how we know’ and whether the ‘how we know’ is the right kind of ‘how’ for the problems that we face today. This has led to a questioning of the way in which we generate knowledge and the way in which this knowledge is used. This critique is not aimed at all knowledge generation it is mostly a frustration that has arisen out of the physical and biological sciences with the realisation that doing good science is just not enough to bring about meaningful change in the world. Trans-disciplinary scientists and practitioners have begun this journey in search of a new kind of science - A science in service of society! This tourist trip will re- trace the few first steps of these emerging ideas so that we can understand where these new ideas have come from and how they may influence our own research. , This document was developed for a postgraduate course on Transdisciplinary research held at Rhodes University. It explores three key theoretical approaches to transdisciplinarity in relation to the question 'Why TD?'.
- Full Text:
- Date Issued: 2016
Walking into Africa in a Chinese way: Hua Jiming’s mindful entry as counterbalance
- Authors: Simbao, Ruth K
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146167 , vital:38501 , ISBN 9791024005799 , https://books.google.co.za/books?id=VGSwDwAAQBAJanddq=Afrique-Asie:+Arts,+espaces,+pratiquesandsource=gbs_navlinks_s
- Description: Book abstract. The links between Africa and Asia are at the very heart of globalization. Understanding its richness and complexity requires a study carried out from various points of view. Particular attention to culture is essential. Centered on the work of visual artists and performers, on town planning, literature and spirituality, the essays gathered here call on many disciplines: art history and history, anthropology, sociology, geography, architecture, comparative literature, visual and culture studies. They constitute a network of crossed views on a subject which no serious reflection on globalization can do today.
- Full Text:
- Date Issued: 2016
- Authors: Simbao, Ruth K
- Date: 2016
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/146167 , vital:38501 , ISBN 9791024005799 , https://books.google.co.za/books?id=VGSwDwAAQBAJanddq=Afrique-Asie:+Arts,+espaces,+pratiquesandsource=gbs_navlinks_s
- Description: Book abstract. The links between Africa and Asia are at the very heart of globalization. Understanding its richness and complexity requires a study carried out from various points of view. Particular attention to culture is essential. Centered on the work of visual artists and performers, on town planning, literature and spirituality, the essays gathered here call on many disciplines: art history and history, anthropology, sociology, geography, architecture, comparative literature, visual and culture studies. They constitute a network of crossed views on a subject which no serious reflection on globalization can do today.
- Full Text:
- Date Issued: 2016
Was Myriophyllum spicatum L.(Haloragaceae) recently introduced to South Africa from Eurasia?
- Weyl, Philip S, Thum, RA, Moody, ML, Newman, RM, Coetzee, Julie A
- Authors: Weyl, Philip S , Thum, RA , Moody, ML , Newman, RM , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425463 , vital:72242 , xlink:href="https://doi.org/10.1016/j.aquabot.2015.09.003"
- Description: There is debate over the native or exotic status of Myriophyllum spicatum L. (Haloragaceae) in South Africa, which has important implications for developing and implementing management strategies. The aim of this study was to determine if M. spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear ribosomal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations. For both these DNA markers, the South African populations were distinct from Eurasian populations, but always stemmed from a European origin. The data suggest that South African and European M. spicatum share a common ancestor, however the divergence of both markers are characteristic of a long period of isolation rather than a recent introduction from Europe. The genetic data from this study suggest that M. spicatum has not been introduced recently, but is most likely a native component of the South African flora.
- Full Text:
- Date Issued: 2016
- Authors: Weyl, Philip S , Thum, RA , Moody, ML , Newman, RM , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425463 , vital:72242 , xlink:href="https://doi.org/10.1016/j.aquabot.2015.09.003"
- Description: There is debate over the native or exotic status of Myriophyllum spicatum L. (Haloragaceae) in South Africa, which has important implications for developing and implementing management strategies. The aim of this study was to determine if M. spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear ribosomal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations. For both these DNA markers, the South African populations were distinct from Eurasian populations, but always stemmed from a European origin. The data suggest that South African and European M. spicatum share a common ancestor, however the divergence of both markers are characteristic of a long period of isolation rather than a recent introduction from Europe. The genetic data from this study suggest that M. spicatum has not been introduced recently, but is most likely a native component of the South African flora.
- Full Text:
- Date Issued: 2016
Water footprint assessment of citrus production in South Africa: A case study of the Lower Sundays River Valley
- Munro, Samantha A, Fraser, Gavin C G, Snowball, Jeanette D, Pahlow, Markus
- Authors: Munro, Samantha A , Fraser, Gavin C G , Snowball, Jeanette D , Pahlow, Markus
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69240 , vital:29463 , https://doi.org/10.1016/j.jclepro.2016.06.142
- Description: Water footprint assessment is a developing method that is being increasingly applied to quantify water use, prioritise reductions, assess sustainability and provide information to achieve sustainable, efficient, and equitable water use. The objectives of this paper were to conduct a water footprint assessment of primary citrus production within the Lower Sundays River Valley in South Africa using local, high-resolution data and to examine indicators (water scarcity, pollution, efficiency, productivity and access) to determine the sustainability of blue, green and grey water footprints of a wet, dry and average year. Lemons were found to have the lowest blue and combined green-blue water footprint per ton of production across all climatic years, followed by soft citrus, valencias and navels. Valencias had the lowest, and navels the highest grey WF (relating to inorganic nitrogen). Lemons, despite their high crop water and fertiliser requirements, were regarded more economically efficient in comparison to valencias, soft citrus and navels, in that they provided higher net income and more employment hours per m3 of water in comparison to other citrus crops. In an average season, lemons generated approximately 39% more income per m3 of water than navels, despite navels being the dominant cultivar. Blue water consumption for citrus in the catchment was calculated to be 58.7 Mm3 for an average season and 89.2 Mm3 for a dry season. Due to an inter-basin transfer scheme, no physical water scarcity occurred, and both environmental and basic human needs are met. Water pollution levels related to nitrogen however, exceeded the assimilative capacity of the run-off in dry years. The area also experiences institutional and infrastructural scarcity and 14% of the population do not have access to piped water. Stakeholders and governments may use the results of water footprint assessments to determine the status of river basins, make evaluations for future water usage and the potential impacts of expanding agriculture and different management strategies. Including environmental and socio-economic indicators will also improve the integrity of water footprint assessments.
- Full Text: false
- Date Issued: 2016
- Authors: Munro, Samantha A , Fraser, Gavin C G , Snowball, Jeanette D , Pahlow, Markus
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69240 , vital:29463 , https://doi.org/10.1016/j.jclepro.2016.06.142
- Description: Water footprint assessment is a developing method that is being increasingly applied to quantify water use, prioritise reductions, assess sustainability and provide information to achieve sustainable, efficient, and equitable water use. The objectives of this paper were to conduct a water footprint assessment of primary citrus production within the Lower Sundays River Valley in South Africa using local, high-resolution data and to examine indicators (water scarcity, pollution, efficiency, productivity and access) to determine the sustainability of blue, green and grey water footprints of a wet, dry and average year. Lemons were found to have the lowest blue and combined green-blue water footprint per ton of production across all climatic years, followed by soft citrus, valencias and navels. Valencias had the lowest, and navels the highest grey WF (relating to inorganic nitrogen). Lemons, despite their high crop water and fertiliser requirements, were regarded more economically efficient in comparison to valencias, soft citrus and navels, in that they provided higher net income and more employment hours per m3 of water in comparison to other citrus crops. In an average season, lemons generated approximately 39% more income per m3 of water than navels, despite navels being the dominant cultivar. Blue water consumption for citrus in the catchment was calculated to be 58.7 Mm3 for an average season and 89.2 Mm3 for a dry season. Due to an inter-basin transfer scheme, no physical water scarcity occurred, and both environmental and basic human needs are met. Water pollution levels related to nitrogen however, exceeded the assimilative capacity of the run-off in dry years. The area also experiences institutional and infrastructural scarcity and 14% of the population do not have access to piped water. Stakeholders and governments may use the results of water footprint assessments to determine the status of river basins, make evaluations for future water usage and the potential impacts of expanding agriculture and different management strategies. Including environmental and socio-economic indicators will also improve the integrity of water footprint assessments.
- Full Text: false
- Date Issued: 2016
Ways of belonging: meanings of “Nature” among Xhosa-speaking township residents in South Africa
- Cocks, Michelle L, Alexander, Jamie K, Mogano, Lydia, Vetter, Susan M
- Authors: Cocks, Michelle L , Alexander, Jamie K , Mogano, Lydia , Vetter, Susan M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66021 , vital:28877 , https://doi.org/10.2993/0278-0771-36.4.820
- Description: publisher version , The concept of biocultural diversity, originally used to describe indigenous people and their ways of using and managing natural resources, has more recently been applied within the urban context to understand the variability of interactions between humans and nature. Significant progress has been made internationally in acknowledging the need to preserve and maintain green spaces in urban environments. Current efforts to address the need for greening urban areas in South Africa primarily focus on the establishment and maintenance of botanical gardens and parks as well as various green belts within the urban landscape. South Africa's urban areas are overwhelmingly shaped by the historical segregation of space and stark disparities in wealth. The distribution, quality, and extent of urban green spaces reflect this. Many township dwellers do not have access to these amenities and their interactions with nature are thus usually constrained to access to municipal commonages. This article explores how areas of natural vegetation in municipal commonages on the outskirts of urban centers in South Africa continue to offer places of cultural, spiritual, and restorative importance to Xhosa-speaking township dwellers. A case study from Grahamstown, an urban center in the Eastern Cape with a population of around 80,000, illustrates how ability to access and move through such places contributes to people's well-being, identity formation, and shared heritage. A case is made for adopting a biocultural diversity approach to spatial planning and urban development within the South African context.
- Full Text: false
- Date Issued: 2016
- Authors: Cocks, Michelle L , Alexander, Jamie K , Mogano, Lydia , Vetter, Susan M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66021 , vital:28877 , https://doi.org/10.2993/0278-0771-36.4.820
- Description: publisher version , The concept of biocultural diversity, originally used to describe indigenous people and their ways of using and managing natural resources, has more recently been applied within the urban context to understand the variability of interactions between humans and nature. Significant progress has been made internationally in acknowledging the need to preserve and maintain green spaces in urban environments. Current efforts to address the need for greening urban areas in South Africa primarily focus on the establishment and maintenance of botanical gardens and parks as well as various green belts within the urban landscape. South Africa's urban areas are overwhelmingly shaped by the historical segregation of space and stark disparities in wealth. The distribution, quality, and extent of urban green spaces reflect this. Many township dwellers do not have access to these amenities and their interactions with nature are thus usually constrained to access to municipal commonages. This article explores how areas of natural vegetation in municipal commonages on the outskirts of urban centers in South Africa continue to offer places of cultural, spiritual, and restorative importance to Xhosa-speaking township dwellers. A case study from Grahamstown, an urban center in the Eastern Cape with a population of around 80,000, illustrates how ability to access and move through such places contributes to people's well-being, identity formation, and shared heritage. A case is made for adopting a biocultural diversity approach to spatial planning and urban development within the South African context.
- Full Text: false
- Date Issued: 2016