Pharmacotherapeutic interventions for bipolar disorder type II: addressing multiple symptoms and approaches with a particular emphasis on strategies in lower and middle-income countries
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3872 , vital:43960
- Full Text:
- Authors: Christoffel Grobler
- Date: 2019
- Language: English
- Type: Article
- Identifier: http://hdl.handle.net/11260/3872 , vital:43960
- Full Text:
A passive auxiliary circuit with interphase transformer applied in 12-pulse converters to provide clean power utility interface
- Shih, Der-Chun, Young, Chung-Ming, Whiteley, Chris G
- Authors: Shih, Der-Chun , Young, Chung-Ming , Whiteley, Chris G
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67095 , vital:29031 , https://doi.org/10.1080/02533839.2016.1230029
- Description: publisher version , This paper proposes a passive auxiliary circuit which can be added to an interphase transformer (PAC + IPT) configuration to reduce the total harmonic distortion (THD) existing in 12-pulse diode rectifier converter systems at AC mains. The proposed PAC + IPT compensation method is a simple structure, with low power consumption and requires no extra DC power supply. We present the theoretical analysis of the proposed topology that lessens the total harmonic distortion (THD) and evaluate the dynamic simulation results on a 12-pulse converter system and a 3-kW laboratory prototype. Both the simulation and the experimental results show that the proposed PAC + IPT compensation method can improve the power quality and provide a clean power utility interface of AC line input currents for a conventional 12-pulse diode rectifier converter.
- Full Text: false
- Date Issued: 2016
- Authors: Shih, Der-Chun , Young, Chung-Ming , Whiteley, Chris G
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67095 , vital:29031 , https://doi.org/10.1080/02533839.2016.1230029
- Description: publisher version , This paper proposes a passive auxiliary circuit which can be added to an interphase transformer (PAC + IPT) configuration to reduce the total harmonic distortion (THD) existing in 12-pulse diode rectifier converter systems at AC mains. The proposed PAC + IPT compensation method is a simple structure, with low power consumption and requires no extra DC power supply. We present the theoretical analysis of the proposed topology that lessens the total harmonic distortion (THD) and evaluate the dynamic simulation results on a 12-pulse converter system and a 3-kW laboratory prototype. Both the simulation and the experimental results show that the proposed PAC + IPT compensation method can improve the power quality and provide a clean power utility interface of AC line input currents for a conventional 12-pulse diode rectifier converter.
- Full Text: false
- Date Issued: 2016
Diet of the endemic bivalve Solen cylindraceus inferred from stable isotope analysis in the Kariega Estuary, South Africa
- Nel, Holly A, Froneman, P William
- Authors: Nel, Holly A , Froneman, P William
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67933 , vital:29170 , https://doi.org/10.1080/13235818.2016.1175917
- Description: Publisher version , Sedentary filter-feeders such as the razor clam (Solen cylindraceus) are believed to indiscriminately exploit a carbon source derived from particulate organic matter (POM). POM demonstrates a high degree of spatial and temporal variability in composition, which may result in intraspecific dietary variation. This study aimed to investigate seasonal ontogenetic shifts in the feeding ecology of S. cylindraceus using dual stable isotopic (δ13C and δ15N) analyses in the oligotrophic temperate permanently open Kariega Estuary, South Africa. Mixing model results demonstrate that the different size classes of S. cylindraceus had a diet comprised mainly of POM. However, size grouping did have a significant effect on carbon and nitrogen signatures. Specifically, during winter, carbon isotopic signatures became more depleted with a decrease in size, while both winter and summer δ15N values became more nitrogen enriched with an increase in size. The observed trend in the ratios can likely be ascribed to the hydrodynamics of the system. Data from this study suggest that there may be some degree of variation among the different size cohorts, although this needs further investigation.
- Full Text: false
- Date Issued: 2016
- Authors: Nel, Holly A , Froneman, P William
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67933 , vital:29170 , https://doi.org/10.1080/13235818.2016.1175917
- Description: Publisher version , Sedentary filter-feeders such as the razor clam (Solen cylindraceus) are believed to indiscriminately exploit a carbon source derived from particulate organic matter (POM). POM demonstrates a high degree of spatial and temporal variability in composition, which may result in intraspecific dietary variation. This study aimed to investigate seasonal ontogenetic shifts in the feeding ecology of S. cylindraceus using dual stable isotopic (δ13C and δ15N) analyses in the oligotrophic temperate permanently open Kariega Estuary, South Africa. Mixing model results demonstrate that the different size classes of S. cylindraceus had a diet comprised mainly of POM. However, size grouping did have a significant effect on carbon and nitrogen signatures. Specifically, during winter, carbon isotopic signatures became more depleted with a decrease in size, while both winter and summer δ15N values became more nitrogen enriched with an increase in size. The observed trend in the ratios can likely be ascribed to the hydrodynamics of the system. Data from this study suggest that there may be some degree of variation among the different size cohorts, although this needs further investigation.
- Full Text: false
- Date Issued: 2016
An assessment of chlorophyll-a concentration spatio-temporal variation using Landsat satellite data, in a small tropical reservoir
- Dalu, Tatenda, Dube, Timothy, Froneman, P William, Sachikonye, Mwazvita T B, Clegg, Bruce W, Nhiwatiwa, Tamuka
- Authors: Dalu, Tatenda , Dube, Timothy , Froneman, P William , Sachikonye, Mwazvita T B , Clegg, Bruce W , Nhiwatiwa, Tamuka
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68042 , vital:29189 , https://doi.org/10.1080/10106049.2015.1027292
- Description: Publisher version , Traditional approaches to monitoring aquatic systems are often limited by the need for data collection which often is time-consuming, expensive and non-continuous. The aim of the study was to map the spatio-temporal chlorophyll-a concentration changes in Malilangwe Reservoir, Zimbabwe as an indicator of phytoplankton biomass and trophic state when the reservoir was full (year 2000) and at its lowest capacity (year 2011), using readily available Landsat multispectral images. Medium-spatial resolution (30 m) Landsat multispectral Thematic Mapper TM 5 and ETM+ images for May to December 1999–2000 and 2010–2011 were used to derive chlorophyll-a concentrations. In situ measured chlorophyll-a and total suspended solids (TSS) concentrations for 2011 were employed to validate the Landsat chlorophyll-a and TSS estimates. The study results indicate that Landsat-derived chlorophyll-a and TSS estimates were comparable with field measurements. There was a considerable wet vs. dry season differences in total chlorophyll-a concentration, Secchi disc depth, TSS and turbidity within the reservoir. Using Permutational multivariate analyses of variance (PERMANOVA) analysis, there were significant differences (p < 0.0001) for chlorophyll-a concentration among sites, months and years whereas TSS was significant during the study months (p < 0.05). A strong positive significant correlation among both predicted TSS vs. chlorophyll-a and measured vs. predicted chlorophyll-a and TSS concentrations as well as an inverse relationship between reservoir chlorophyll-a concentrations and water level were found (p < 0.001 in all cases). In conclusion, total chlorophyll-a concentration in Malilangwe Reservoir was successfully derived from Landsat remote sensing data suggesting that the Landsat sensor is suitable for real-time monitoring over relatively short timescales and for small reservoirs. Satellite data can allow for surveying of chlorophyll-a concentration in aquatic ecosystems, thus, providing invaluable data in data scarce (limited on site ground measurements) environments.
- Full Text: false
- Date Issued: 2015
- Authors: Dalu, Tatenda , Dube, Timothy , Froneman, P William , Sachikonye, Mwazvita T B , Clegg, Bruce W , Nhiwatiwa, Tamuka
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68042 , vital:29189 , https://doi.org/10.1080/10106049.2015.1027292
- Description: Publisher version , Traditional approaches to monitoring aquatic systems are often limited by the need for data collection which often is time-consuming, expensive and non-continuous. The aim of the study was to map the spatio-temporal chlorophyll-a concentration changes in Malilangwe Reservoir, Zimbabwe as an indicator of phytoplankton biomass and trophic state when the reservoir was full (year 2000) and at its lowest capacity (year 2011), using readily available Landsat multispectral images. Medium-spatial resolution (30 m) Landsat multispectral Thematic Mapper TM 5 and ETM+ images for May to December 1999–2000 and 2010–2011 were used to derive chlorophyll-a concentrations. In situ measured chlorophyll-a and total suspended solids (TSS) concentrations for 2011 were employed to validate the Landsat chlorophyll-a and TSS estimates. The study results indicate that Landsat-derived chlorophyll-a and TSS estimates were comparable with field measurements. There was a considerable wet vs. dry season differences in total chlorophyll-a concentration, Secchi disc depth, TSS and turbidity within the reservoir. Using Permutational multivariate analyses of variance (PERMANOVA) analysis, there were significant differences (p < 0.0001) for chlorophyll-a concentration among sites, months and years whereas TSS was significant during the study months (p < 0.05). A strong positive significant correlation among both predicted TSS vs. chlorophyll-a and measured vs. predicted chlorophyll-a and TSS concentrations as well as an inverse relationship between reservoir chlorophyll-a concentrations and water level were found (p < 0.001 in all cases). In conclusion, total chlorophyll-a concentration in Malilangwe Reservoir was successfully derived from Landsat remote sensing data suggesting that the Landsat sensor is suitable for real-time monitoring over relatively short timescales and for small reservoirs. Satellite data can allow for surveying of chlorophyll-a concentration in aquatic ecosystems, thus, providing invaluable data in data scarce (limited on site ground measurements) environments.
- Full Text: false
- Date Issued: 2015
Influence of mouth status on population structure of southern African endemic estuarine-spawning ichthyofauna in a temperate, temporarily open/closed estuary
- Tweddle, Gavin P, Froneman, P William
- Authors: Tweddle, Gavin P , Froneman, P William
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68071 , vital:29195 , https://doi.org/10.2989/16085914.2015.1051940
- Description: Publisher version , The effect of mouth status on the population structure of three endemic estuarine-spawning fish species was assessed using seine nets from November 2005 to October 2007 in the temporarily open/closed Mpekweni Estuary, Eastern Cape, South Africa. Collectively, these three species accounted for more than 60% of the total fish abundance within the estuary. Monthly length frequency data were analysed. Two species, Gilchristella aestuaria and Glossogobius callidus, displayed normally distributed populations throughout, with recruitment/abundance peaks between spring and autumn, and were unaffected by open mouth and extended marine connection conditions. Atherina breviceps, however, displayed multiple modal peaks in its combined population distribution, suggesting a greater influence of mouth condition on its population structure. Retrospective analyses of the various cohorts for A. breviceps identified peaks in recruitment/abundance during summer, coinciding with open-mouth conditions and, to a lesser extent, with overwash events. This study highlights the importance of mouth phase, not only on the recruitment and population distribution of marine-spawning species, but also on estuarine-spawning fish in temporarily open/closed estuaries along the South African coastline.
- Full Text: false
- Date Issued: 2015
- Authors: Tweddle, Gavin P , Froneman, P William
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68071 , vital:29195 , https://doi.org/10.2989/16085914.2015.1051940
- Description: Publisher version , The effect of mouth status on the population structure of three endemic estuarine-spawning fish species was assessed using seine nets from November 2005 to October 2007 in the temporarily open/closed Mpekweni Estuary, Eastern Cape, South Africa. Collectively, these three species accounted for more than 60% of the total fish abundance within the estuary. Monthly length frequency data were analysed. Two species, Gilchristella aestuaria and Glossogobius callidus, displayed normally distributed populations throughout, with recruitment/abundance peaks between spring and autumn, and were unaffected by open mouth and extended marine connection conditions. Atherina breviceps, however, displayed multiple modal peaks in its combined population distribution, suggesting a greater influence of mouth condition on its population structure. Retrospective analyses of the various cohorts for A. breviceps identified peaks in recruitment/abundance during summer, coinciding with open-mouth conditions and, to a lesser extent, with overwash events. This study highlights the importance of mouth phase, not only on the recruitment and population distribution of marine-spawning species, but also on estuarine-spawning fish in temporarily open/closed estuaries along the South African coastline.
- Full Text: false
- Date Issued: 2015
Can δ15N and δ13C stable isotopes and fatty acid signatures indicate changes in phytobenthos composition on an artificial substrate?
- Dalu, Tatenda, Froneman, P William
- Authors: Dalu, Tatenda , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68086 , vital:29197 , https://doi.org/10.2989/16085914.2014.974018
- Description: Publisher version , Temporal changes in fatty acid composition and δ15N, δ13C stable isotope values of the phytobenthos growing on artificial clay substrates under natural conditions over a 28-day period at an upstream and a downstream site in the Kowie River near Grahamstown were investigated in 2012. High concentrations of diatom markers 16:1ω7 and 20:5ω3 fatty acids were recorded, especially at the downstream site, reflecting the importance of diatoms in contributing to the phytobenthos communities at that station. After day 7 at the downstream site the average δ15N value of the phytobenthos was lighter, gradually increasing by ∼2‰ and ∼5‰ overall to heavier values on day 28. At the upstream site there were no significant changes (<1‰ increase) in δ15N values of the phytobenthos over time. Stable nitrogen (δ15N) and carbon (δ13C) signatures in the phytobenthos communities were significantly different between sites (one-way ANOVA; p < 0.001). The stable isotope values and fatty acid concentrations of phytobenthos at the downstream site were different to those of the phytobenthos at the upstream site, and they changed concurrently with changes in the phytobenthos community structure. At the downstream site there was a strong correlation of the δ15N of phytobenthos with nitrates (R = 0.56) and time (weeks; R = 0.81). However, the fatty acids were not specific enough to characterise the composition of phytobenthos communities. Other biomarker methods, such as stable isotopes and microscopic examination of the communities, were found to be useful. The results from this relatively small-scale tile experiment indicate the complexity of changes in fatty acid composition and δ15N, δ13C stable isotope values of a phytobenthos community. Stable isotope and fatty acid composition can be successfully used to map changes in phytobenthos composition and carbon and nitrogen flow patterns along a river continuum.
- Full Text: false
- Date Issued: 2014
- Authors: Dalu, Tatenda , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68086 , vital:29197 , https://doi.org/10.2989/16085914.2014.974018
- Description: Publisher version , Temporal changes in fatty acid composition and δ15N, δ13C stable isotope values of the phytobenthos growing on artificial clay substrates under natural conditions over a 28-day period at an upstream and a downstream site in the Kowie River near Grahamstown were investigated in 2012. High concentrations of diatom markers 16:1ω7 and 20:5ω3 fatty acids were recorded, especially at the downstream site, reflecting the importance of diatoms in contributing to the phytobenthos communities at that station. After day 7 at the downstream site the average δ15N value of the phytobenthos was lighter, gradually increasing by ∼2‰ and ∼5‰ overall to heavier values on day 28. At the upstream site there were no significant changes (<1‰ increase) in δ15N values of the phytobenthos over time. Stable nitrogen (δ15N) and carbon (δ13C) signatures in the phytobenthos communities were significantly different between sites (one-way ANOVA; p < 0.001). The stable isotope values and fatty acid concentrations of phytobenthos at the downstream site were different to those of the phytobenthos at the upstream site, and they changed concurrently with changes in the phytobenthos community structure. At the downstream site there was a strong correlation of the δ15N of phytobenthos with nitrates (R = 0.56) and time (weeks; R = 0.81). However, the fatty acids were not specific enough to characterise the composition of phytobenthos communities. Other biomarker methods, such as stable isotopes and microscopic examination of the communities, were found to be useful. The results from this relatively small-scale tile experiment indicate the complexity of changes in fatty acid composition and δ15N, δ13C stable isotope values of a phytobenthos community. Stable isotope and fatty acid composition can be successfully used to map changes in phytobenthos composition and carbon and nitrogen flow patterns along a river continuum.
- Full Text: false
- Date Issued: 2014
Temporal and spatial variability in the abundance, biomass and distribution of Palaemon peringueyi (Decapoda: Crustacea) are influenced by biological but not physico-chemical factors in the permanently open Kariega Estuary, South Africa
- Nyalungu, Nonhlanhla P, Hodgson, Alan N, Froneman, P William, Dopolo, M, Masubelele, M
- Authors: Nyalungu, Nonhlanhla P , Hodgson, Alan N , Froneman, P William , Dopolo, M , Masubelele, M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68106 , vital:29200 , https://doi.org/10.2989/16085914.2014.960792
- Description: Publisher version , Biological and physico-chemical factors affecting abundance and biomass of shrimp Palaemon peringueyi were investigated in 2010–2011 in the lower, middle and upper reaches of the freshwater-deprived permanently open Kariega Estuary. Shrimp abundance and biomass ranged from 0 to 88 ind. m−2 and 0 to 4.4 g wwt m−2, respectively. Shrimps were most abundant in the lower reach, and highest abundances and biomasses were recorded in the lower reach in June when salinities were low. The shrimps were almost always absent in the upper reach. Juveniles were found mostly in the lower and middle reaches, whereas adults were distributed in all three reaches. Regression analyses showed no statistically significant relationship for either abundance or biomass of the shrimps with temperature, salinity and dissolved oxygen (p > 0.05). The relationship between shrimp abundance and biomass and vegetation cover was positive and statistically significant (R2 = 0.109 and 0.185, respectively; p < 0.05). Vegetation cover plays an important role in determining the presence, distribution and abundance or biomass of P. peringueyi in this estuary.
- Full Text: false
- Date Issued: 2014
- Authors: Nyalungu, Nonhlanhla P , Hodgson, Alan N , Froneman, P William , Dopolo, M , Masubelele, M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68106 , vital:29200 , https://doi.org/10.2989/16085914.2014.960792
- Description: Publisher version , Biological and physico-chemical factors affecting abundance and biomass of shrimp Palaemon peringueyi were investigated in 2010–2011 in the lower, middle and upper reaches of the freshwater-deprived permanently open Kariega Estuary. Shrimp abundance and biomass ranged from 0 to 88 ind. m−2 and 0 to 4.4 g wwt m−2, respectively. Shrimps were most abundant in the lower reach, and highest abundances and biomasses were recorded in the lower reach in June when salinities were low. The shrimps were almost always absent in the upper reach. Juveniles were found mostly in the lower and middle reaches, whereas adults were distributed in all three reaches. Regression analyses showed no statistically significant relationship for either abundance or biomass of the shrimps with temperature, salinity and dissolved oxygen (p > 0.05). The relationship between shrimp abundance and biomass and vegetation cover was positive and statistically significant (R2 = 0.109 and 0.185, respectively; p < 0.05). Vegetation cover plays an important role in determining the presence, distribution and abundance or biomass of P. peringueyi in this estuary.
- Full Text: false
- Date Issued: 2014
Using multivariate analysis and stable isotopes to assess the effects of substrate type on phytobenthos communities
- Dalu, Tatenda, Richoux, Nicole B, Froneman, P William
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
- Date Issued: 2014
- Authors: Dalu, Tatenda , Richoux, Nicole B , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68123 , vital:29201 , https://doi.org/10.5268/IW-4.4.719
- Description: Publisher version , For more than a century, artificial substrates have been employed in phytobenthos studies. In the present study, we compared the phytobenthos community structure in a field experiment over 3 seasons (summer, autumn, and winter) on 3 types of artificial substrates (brick, brown clay tiles, and grey clay tiles) and 3 natural substrates (macrophytes, rocks, and sediment) in a small, temperate system. A combination of multivariate analyses (cluster, multi-response permutation procedure, indicator species [IndVal], and canonical correspondence analysis [CCA]) and stable isotope analysis was used. We identified 96 total phytobenthos taxa. Artificial substrates resulted in different substrate communities, as shown by stable isotope analysis, cluster analysis, and a multi-response permutation procedure, with only those communities growing on grey tiles being similar to natural substrate communities. Overall, artificial substrates exhibited slightly higher species richness compared to natural substrates over the 3 seasons, although there were no significant differences (p> 0.05). Phytobenthos grown on brown tiles, rocks, and bricks showed seasonal variability of the carbon isotope δ13C values using one-way ANOVA (p< 0.05). Phytobenthos community structure did not show great seasonal variation; however, CCA identified water flow, conductivity, ammonium, phosphate, and water depth as important in structuring phytobenthos communities on different substrates. IndVal analysis showed that common phytobenthos taxa were not restricted to a single substrate, but preference was generally high for natural substrate, especially rocks, compared to artificial substrates. Substrate microhabitat type seems to influence the communities within the study areas.
- Full Text: false
- Date Issued: 2014
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