Lattice-valued continuous convergence is induced by a lattice-valued uniform convergence structure
- Authors: Jäger, Gunter
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6824 , http://hdl.handle.net/10962/d1012332
- Description: We define a stratified L-uniform convergence structure on the set of all continuous mappings from a stratified L-limit space to a stratified L-uniform convergence space. This structure induces L-continuous convergence. This shows that the category of all L-limit-uniformizable spaces is cartesian closed.
- Full Text:
- Date Issued: 2006
- Authors: Jäger, Gunter
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6824 , http://hdl.handle.net/10962/d1012332
- Description: We define a stratified L-uniform convergence structure on the set of all continuous mappings from a stratified L-limit space to a stratified L-uniform convergence space. This structure induces L-continuous convergence. This shows that the category of all L-limit-uniformizable spaces is cartesian closed.
- Full Text:
- Date Issued: 2006
Maximum likelihood and Bayesian approaches to stock assessment when data are questionable
- Booth, Anthony J, Quinn II, T J
- Authors: Booth, Anthony J , Quinn II, T J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6764 , http://hdl.handle.net/10962/d1007962
- Description: This study examines the use of age-structured maximum likelihood and Bayesian approaches for stock assessment of the Namibian monkfish, Lophius vomerinus, resource with questionable data, in which time series are short, abundance indices are variable, and research data conflict with commercial data. Bayesian approaches with both noninformative and informative priors are investigated to determine if they enhance estimation stability. Three data scenarios are assessed: commercial and research survey data, research survey data only, and commercial data only. Both statistical approaches show that resource abundance has decreased with exploitable biomass estimated at approximately 44% of pristine levels. The maximum likelihood and the Bayesian approach with noninformative priors result in similar estimates. As the abundance data contained little information pertaining to possible density dependence within the stock–recruit relationship, only a Bayesian approach with informative priors reduces uncertainty in the steepness parameter h. Estimated management quantities are sensitive both to the set of data sources and whether prior information was informative or not. The strengths of the Bayesian approach include the integration of prior information with uncertain data, the exploration of data conflicts, and the ability to show the uncertainty in estimates of management parameters. Its weakness is that estimation stability is dependent on the choice of priors, which alters some posterior distributions of management quantities.
- Full Text:
- Date Issued: 2006
- Authors: Booth, Anthony J , Quinn II, T J
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6764 , http://hdl.handle.net/10962/d1007962
- Description: This study examines the use of age-structured maximum likelihood and Bayesian approaches for stock assessment of the Namibian monkfish, Lophius vomerinus, resource with questionable data, in which time series are short, abundance indices are variable, and research data conflict with commercial data. Bayesian approaches with both noninformative and informative priors are investigated to determine if they enhance estimation stability. Three data scenarios are assessed: commercial and research survey data, research survey data only, and commercial data only. Both statistical approaches show that resource abundance has decreased with exploitable biomass estimated at approximately 44% of pristine levels. The maximum likelihood and the Bayesian approach with noninformative priors result in similar estimates. As the abundance data contained little information pertaining to possible density dependence within the stock–recruit relationship, only a Bayesian approach with informative priors reduces uncertainty in the steepness parameter h. Estimated management quantities are sensitive both to the set of data sources and whether prior information was informative or not. The strengths of the Bayesian approach include the integration of prior information with uncertain data, the exploration of data conflicts, and the ability to show the uncertainty in estimates of management parameters. Its weakness is that estimation stability is dependent on the choice of priors, which alters some posterior distributions of management quantities.
- Full Text:
- Date Issued: 2006
Medicines information and adherence in HIV/AIDS patients
- Mansoor, Leila E, Dowse, Roslind
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6395 , http://hdl.handle.net/10962/d1006319
- Description: Background: Providing written medicines information is being legislated in an increasing number of countries worldwide, with the patient information leaflet (PIL) being the most widely used method for conveying health information. The impact of providing such information on adherence to therapy is reportedly unpredictable. Therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and related opportunistic infections usually involves polytherapy and complex regimens, both of which are risk factors for non-adherence. The objective of this study was to assess the impact of medicines information on adherence to chronic co-trimoxazole therapy in low-literate HIV/AIDS patients. Methods: Two different PILs were designed for co-trimoxazole tablets and were available in both English and isiXhosa. Participants were randomly allocated to a control group (receiving no PIL), group A (receiving a 'complex PIL') and group B (receiving a 'simple PIL' incorporating pictograms). At the first interview, demographic data were collected and the time, date and day that the participant would take his/her first tablet of the month's course was also documented. In a follow-up interview adherence to therapy was assessed using two methods; self-report and tablet count. Results: The medicines information materials incorporating simple text and pictograms resulted in significantly improved adherence to therapy in the short term, whereas a non-significant increase in adherence was associated with the availability of the more complex information. This was shown by both the self-reported assessment as well as the tablet count. Conclusion: This research suggests that appropriately designed written material can have a positive impact in improving adherence and, together with verbal consultation, are essential for enabling patients to make appropriate decisions about their medicine taking.
- Full Text:
- Date Issued: 2006
- Authors: Mansoor, Leila E , Dowse, Roslind
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6395 , http://hdl.handle.net/10962/d1006319
- Description: Background: Providing written medicines information is being legislated in an increasing number of countries worldwide, with the patient information leaflet (PIL) being the most widely used method for conveying health information. The impact of providing such information on adherence to therapy is reportedly unpredictable. Therapy for human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) and related opportunistic infections usually involves polytherapy and complex regimens, both of which are risk factors for non-adherence. The objective of this study was to assess the impact of medicines information on adherence to chronic co-trimoxazole therapy in low-literate HIV/AIDS patients. Methods: Two different PILs were designed for co-trimoxazole tablets and were available in both English and isiXhosa. Participants were randomly allocated to a control group (receiving no PIL), group A (receiving a 'complex PIL') and group B (receiving a 'simple PIL' incorporating pictograms). At the first interview, demographic data were collected and the time, date and day that the participant would take his/her first tablet of the month's course was also documented. In a follow-up interview adherence to therapy was assessed using two methods; self-report and tablet count. Results: The medicines information materials incorporating simple text and pictograms resulted in significantly improved adherence to therapy in the short term, whereas a non-significant increase in adherence was associated with the availability of the more complex information. This was shown by both the self-reported assessment as well as the tablet count. Conclusion: This research suggests that appropriately designed written material can have a positive impact in improving adherence and, together with verbal consultation, are essential for enabling patients to make appropriate decisions about their medicine taking.
- Full Text:
- Date Issued: 2006
Molecular biology studies on the coelacanth: a review
- Modisakeng, Keoagile W, Amemiya, Chris T, Dorrington, Rosemary A, Blatch, Gregory L
- Authors: Modisakeng, Keoagile W , Amemiya, Chris T , Dorrington, Rosemary A , Blatch, Gregory L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6466 , http://hdl.handle.net/10962/d1005795
- Description: The discovery of the African coelacanth in 1938 and subsequently the Indonesian coelacanth in 1998 has resulted in a keen interest in molecular studies on the coelacanth. A major focus has been on the phylogenetic position of the coelacanth. Lobe-finned fish such as the coelacanth are thought to be at the base of the evolutionary branch of fish leading to tetrapods. These studies have further aimed to resolve the phylogenetic relationship of extant lobe-finned fish (two coelacanth species and the lungfishes) to vertebrates. Notwithstanding the lack of readily accessible good-quality coelacanth tissue, several major contributions to coelacanth molecular studies and biology have been possible. The mitochondrial genome sequences of both species of the coelacanth suggest that they diverged from one another 40–30 million years ago. A number of large gene families such as the HOX, protocadherin and heat shock protein clusters have been characterized. Furthermore, the recent successful construction of a large-insert (150–200 kilobase) genomic library of the Indonesian coelacanth will prove to be an invaluable tool in both comparative and functional genomics. Here we summarize and evaluate the current status of molecular research, published and databased, for both the African (Latimeria chalumnae) and the Indonesian (Latimeria menadoensis) coelacanth.
- Full Text:
- Date Issued: 2006
- Authors: Modisakeng, Keoagile W , Amemiya, Chris T , Dorrington, Rosemary A , Blatch, Gregory L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6466 , http://hdl.handle.net/10962/d1005795
- Description: The discovery of the African coelacanth in 1938 and subsequently the Indonesian coelacanth in 1998 has resulted in a keen interest in molecular studies on the coelacanth. A major focus has been on the phylogenetic position of the coelacanth. Lobe-finned fish such as the coelacanth are thought to be at the base of the evolutionary branch of fish leading to tetrapods. These studies have further aimed to resolve the phylogenetic relationship of extant lobe-finned fish (two coelacanth species and the lungfishes) to vertebrates. Notwithstanding the lack of readily accessible good-quality coelacanth tissue, several major contributions to coelacanth molecular studies and biology have been possible. The mitochondrial genome sequences of both species of the coelacanth suggest that they diverged from one another 40–30 million years ago. A number of large gene families such as the HOX, protocadherin and heat shock protein clusters have been characterized. Furthermore, the recent successful construction of a large-insert (150–200 kilobase) genomic library of the Indonesian coelacanth will prove to be an invaluable tool in both comparative and functional genomics. Here we summarize and evaluate the current status of molecular research, published and databased, for both the African (Latimeria chalumnae) and the Indonesian (Latimeria menadoensis) coelacanth.
- Full Text:
- Date Issued: 2006
Near-real time foF2 predictions using neural networks
- Oyeyemi, E O, McKinnell, Lee-Anne, Poole, Allon W V
- Authors: Oyeyemi, E O , McKinnell, Lee-Anne , Poole, Allon W V
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6804 , http://hdl.handle.net/10962/d1004167
- Description: This paper describes the use of the neural network (NN) technique for the development of a near-real time global foF2 (NRTNN) empirical model. The data used are hourly daily values of foF2 from 26 worldwide ionospheric stations (based on availability) during the period 1976–1986 for training the NN and between 1977 and 1989 for verifying the prediction accuracy. The training data set includes all periods of quiet and disturbed geomagnetic conditions. Two categories of input parameters were used as inputs to the NN. The first category consists of geophysical parameters that are temporally or spatially related to the training stations. The second category, which is related to the foF2 itself, consists of three recent past observations of foF2 (i.e. real-time foF2 (F0), 2 h (F−2) and 1 h (F−1) prior to F0) from four control stations (i.e. Boulder (40.0°N, 254.7°E), Grahamstown (33.3°S, 26.5°E), Dourbes (50.1°N, 4.6°E) and Port Stanley (51.7°S, 302.2°E). The performance of the NRTNN was verified under both geomagnetically quiet and disturbed conditions with observed data from a few verification stations. A comparison of the root mean square error (RMSE) differences between measured values and the NRTNN predictions with our earlier standard foF2 NN empirical model is also illustrated. The results reveal that NRTNN will predict foF2 in near-real time with about 1 MHz RMSE difference anywhere on the globe, provided real time data is available at the four control stations. From the results it is also evident that in addition to the geophysical information from any geographical location, recent past observations of foF2 from these control stations could be used as inputs to a NN for near-real time foF2 predictions. Results also reveal that there is a temporal correlation between measured foF2 values at different locations.
- Full Text:
- Date Issued: 2006
- Authors: Oyeyemi, E O , McKinnell, Lee-Anne , Poole, Allon W V
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6804 , http://hdl.handle.net/10962/d1004167
- Description: This paper describes the use of the neural network (NN) technique for the development of a near-real time global foF2 (NRTNN) empirical model. The data used are hourly daily values of foF2 from 26 worldwide ionospheric stations (based on availability) during the period 1976–1986 for training the NN and between 1977 and 1989 for verifying the prediction accuracy. The training data set includes all periods of quiet and disturbed geomagnetic conditions. Two categories of input parameters were used as inputs to the NN. The first category consists of geophysical parameters that are temporally or spatially related to the training stations. The second category, which is related to the foF2 itself, consists of three recent past observations of foF2 (i.e. real-time foF2 (F0), 2 h (F−2) and 1 h (F−1) prior to F0) from four control stations (i.e. Boulder (40.0°N, 254.7°E), Grahamstown (33.3°S, 26.5°E), Dourbes (50.1°N, 4.6°E) and Port Stanley (51.7°S, 302.2°E). The performance of the NRTNN was verified under both geomagnetically quiet and disturbed conditions with observed data from a few verification stations. A comparison of the root mean square error (RMSE) differences between measured values and the NRTNN predictions with our earlier standard foF2 NN empirical model is also illustrated. The results reveal that NRTNN will predict foF2 in near-real time with about 1 MHz RMSE difference anywhere on the globe, provided real time data is available at the four control stations. From the results it is also evident that in addition to the geophysical information from any geographical location, recent past observations of foF2 from these control stations could be used as inputs to a NN for near-real time foF2 predictions. Results also reveal that there is a temporal correlation between measured foF2 values at different locations.
- Full Text:
- Date Issued: 2006
New and improved : Linda in Java
- Authors: Wells, George C
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6613 , http://hdl.handle.net/10962/d1011511 , http://www.sciencedirect.com/science/article/pii/S0167642305000869
- Description: This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing.
- Full Text:
- Date Issued: 2006
- Authors: Wells, George C
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6613 , http://hdl.handle.net/10962/d1011511 , http://www.sciencedirect.com/science/article/pii/S0167642305000869
- Description: This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing.
- Full Text:
- Date Issued: 2006
Non-steroidal anti-inflammatory agents, tolmetin and sulindac, inhibit liver tryptophan 2,3-dioxygenase activity and alter brain neurotransmitter levels
- Dairam, A, Antunes, Edith M, Saravanan, K S, Daya, Santylal
- Authors: Dairam, A , Antunes, Edith M , Saravanan, K S , Daya, Santylal
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6358 , http://hdl.handle.net/10962/d1006050 , http://dx.doi.org/10.1016/j.lfs.2006.07.028
- Description: Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.
- Full Text:
- Date Issued: 2006
- Authors: Dairam, A , Antunes, Edith M , Saravanan, K S , Daya, Santylal
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6358 , http://hdl.handle.net/10962/d1006050 , http://dx.doi.org/10.1016/j.lfs.2006.07.028
- Description: Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.
- Full Text:
- Date Issued: 2006
Novel amperometric glucose biosensor based on an ether-linked cobalt(II) phthalocyaninecobalt(II) tetraphenylporphyrin pentamer as a redox mediator
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6583 , http://hdl.handle.net/10962/d1004148
- Description: The development of cobalt(II) phthalocyanine–cobalt(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin), (CoPc–(CoTPP)[subscript 4]) pentamer as a novel redox mediator for amperometric enzyme electrode sensitive to glucose is described. A glassy carbon electrode (GCE) was first modified with the pentamer, then followed by the immobilization onto the GCE–CoPc–(CoTPP)[subscript 4] with glucose oxidase (GOx) through cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) and Nafion® cation-exchange polymer. The proposed biosensor displayed good amperometric respose charateristics to glucose in pH 7.0 PBS solution; such as low overpotentials (+400 mV versus Ag|AgCl), very fast amperometric response time (~5 s), linear concentration range extended up to 11 mM, with 10 μM detection limit. The biosensor exhibited electrochemical Michaelis–Menten kinetics and showed an average apparent Michaelis–Menten constant (K′M) of 14.91 ± 0.46 mM over a storage period of 2 weeks.
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6583 , http://hdl.handle.net/10962/d1004148
- Description: The development of cobalt(II) phthalocyanine–cobalt(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin), (CoPc–(CoTPP)[subscript 4]) pentamer as a novel redox mediator for amperometric enzyme electrode sensitive to glucose is described. A glassy carbon electrode (GCE) was first modified with the pentamer, then followed by the immobilization onto the GCE–CoPc–(CoTPP)[subscript 4] with glucose oxidase (GOx) through cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) and Nafion® cation-exchange polymer. The proposed biosensor displayed good amperometric respose charateristics to glucose in pH 7.0 PBS solution; such as low overpotentials (+400 mV versus Ag|AgCl), very fast amperometric response time (~5 s), linear concentration range extended up to 11 mM, with 10 μM detection limit. The biosensor exhibited electrochemical Michaelis–Menten kinetics and showed an average apparent Michaelis–Menten constant (K′M) of 14.91 ± 0.46 mM over a storage period of 2 weeks.
- Full Text:
- Date Issued: 2006
Observations of the habitats and biodiversity of the submarine canyons at Sodwana Bay
- Sink, K J, Boshoff, W, Samaai, Toufiek, Timm, P G, Kerwath, S E
- Authors: Sink, K J , Boshoff, W , Samaai, Toufiek , Timm, P G , Kerwath, S E
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6771 , http://hdl.handle.net/10962/d1008065
- Description: The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them.
- Full Text:
- Date Issued: 2006
- Authors: Sink, K J , Boshoff, W , Samaai, Toufiek , Timm, P G , Kerwath, S E
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6771 , http://hdl.handle.net/10962/d1008065
- Description: The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them.
- Full Text:
- Date Issued: 2006
Oceanographic environment of the Sodwana Bay coelacanths (Latimeria chalumnae), South Africa
- Roberts, M J, Ribbink, Anthony J, Morris, T
- Authors: Roberts, M J , Ribbink, Anthony J , Morris, T
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7156 , http://hdl.handle.net/10962/d1011883
- Description: Trimix scuba divers discovered coelacanths in Jesser Canyon at a depth of 104 m on the northern KwaZulu-Natal (KZN) coast (Sodwana Bay) in October 2000. The existence of these animals at such a shallow depth and in the swift and powerful Agulhas Current led to a suggestion that this might be an isolated group swept well away from the main population in the Comoros, where they live at depths of 200–350 m with little current. Subsequent observations from three manned submersible surveys and one remotely operated vehicle expedition together with recreational diver observations indicate that the South African population of coelacanths has at least 26 individuals, mostly occupying the depth range of 104–140 m in canyons. Seventeen CTD sections collected during four cruises in 2002 and 2003 indicate the temperature range in this habitat to be similar to that found in the Comoros Islands (that is, 15–22°C cf. 15–19°C in the Comoros). However, a 2.5-month-long time series of hourly data collected by a thermistor array deployed near a known coelacanth cave in Wright Canyon indicated greater variation than anticipated, with temperature changes between 16°C and 24°C occurring in a day. Dissolved oxygen levels in this depth zone were found to range between 3.0 ml l[superscript (–1)] and 4.8 ml l[superscript (–1)] compared to 3.5 ml l[superscript (–1)] in the Comoros. The low oxygen values along this coast are a result of the shallow oxygen minimum, which becomes shallower in the southwest Indian Ocean, particularly in the Agulhas Current, than in tropical latitudes. Current velocities measured using a ship-borne ADCP in the depth range 100–140 m at Sodwana were considerably higher than those measured in the Comoros habitat (20–60 cm s[superscript (–1)] cf. 3–4 cm s[superscript (–1)]) and may be an important factor explaining the coelacanths’ occupation of the canyons found along the northern KZN shelf-break.
- Full Text:
- Date Issued: 2006
- Authors: Roberts, M J , Ribbink, Anthony J , Morris, T
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:7156 , http://hdl.handle.net/10962/d1011883
- Description: Trimix scuba divers discovered coelacanths in Jesser Canyon at a depth of 104 m on the northern KwaZulu-Natal (KZN) coast (Sodwana Bay) in October 2000. The existence of these animals at such a shallow depth and in the swift and powerful Agulhas Current led to a suggestion that this might be an isolated group swept well away from the main population in the Comoros, where they live at depths of 200–350 m with little current. Subsequent observations from three manned submersible surveys and one remotely operated vehicle expedition together with recreational diver observations indicate that the South African population of coelacanths has at least 26 individuals, mostly occupying the depth range of 104–140 m in canyons. Seventeen CTD sections collected during four cruises in 2002 and 2003 indicate the temperature range in this habitat to be similar to that found in the Comoros Islands (that is, 15–22°C cf. 15–19°C in the Comoros). However, a 2.5-month-long time series of hourly data collected by a thermistor array deployed near a known coelacanth cave in Wright Canyon indicated greater variation than anticipated, with temperature changes between 16°C and 24°C occurring in a day. Dissolved oxygen levels in this depth zone were found to range between 3.0 ml l[superscript (–1)] and 4.8 ml l[superscript (–1)] compared to 3.5 ml l[superscript (–1)] in the Comoros. The low oxygen values along this coast are a result of the shallow oxygen minimum, which becomes shallower in the southwest Indian Ocean, particularly in the Agulhas Current, than in tropical latitudes. Current velocities measured using a ship-borne ADCP in the depth range 100–140 m at Sodwana were considerably higher than those measured in the Comoros habitat (20–60 cm s[superscript (–1)] cf. 3–4 cm s[superscript (–1)]) and may be an important factor explaining the coelacanths’ occupation of the canyons found along the northern KZN shelf-break.
- Full Text:
- Date Issued: 2006
Oceanographic environment of the Sodwana Bay coelacanths (Latimeria chalumnae), South Africa
- Roberts, M J, Ribbink, A J, Morris, T
- Authors: Roberts, M J , Ribbink, A J , Morris, T
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7126 , http://hdl.handle.net/10962/d1010633
- Description: Trimix scuba divers discovered coelacanths in Jesser Canyon at a depth of 104 m on the northern KwaZulu-Natal (KZN) coast (Sodwana Bay) in October 2000. The existence of these animals at such a shallow depth and in the swift and powerful Agulhas Current led to a suggestion that this might be an isolated group swept well away from the main population in the Comoros, where they live at depths of 200–350 m with little current. Subsequent observations from three manned submersible surveys and one remotely operated vehicle expedition together with recreational diver observations indicate that the South African population of coelacanths has at least 26 individuals, mostly occupying the depth range of 104–140 m in canyons. Seventeen CTD sections collected during four cruises in 2002 and 2003 indicate the temperature range in this habitat to be similar to that found in the Comoros Islands (that is, 15–22°C cf. 15–19°C in the Comoros). However, a 2.5-month-long time series of hourly data collected by a thermistor array deployed near a known coelacanth cave in Wright Canyon indicated greater variation than anticipated, with temperature changes between 16°C and 24°C occurring in a day. Dissolved oxygen levels in this depth zone were found to range between 3.0 ml l[superscript (–1)] and 4.8 ml l[superscript (–1)] compared to 3.5 ml l[superscript (–1)] in the Comoros. The low oxygen values along this coast are a result of the shallow oxygen minimum, which becomes shallower in the southwest Indian Ocean, particularly in the Agulhas Current, than in tropical latitudes. Current velocities measured using a ship-borne ADCP in the depth range 100–140 m at Sodwana were considerably higher than those measured in the Comoros habitat (20–60 cm s[superscript (–1)] cf. 3–4 cm s[superscript (–1)]) and may be an important factor explaining the coelacanths’ occupation of the canyons found along the northern KZN shelf-break.
- Full Text:
- Date Issued: 2006
- Authors: Roberts, M J , Ribbink, A J , Morris, T
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7126 , http://hdl.handle.net/10962/d1010633
- Description: Trimix scuba divers discovered coelacanths in Jesser Canyon at a depth of 104 m on the northern KwaZulu-Natal (KZN) coast (Sodwana Bay) in October 2000. The existence of these animals at such a shallow depth and in the swift and powerful Agulhas Current led to a suggestion that this might be an isolated group swept well away from the main population in the Comoros, where they live at depths of 200–350 m with little current. Subsequent observations from three manned submersible surveys and one remotely operated vehicle expedition together with recreational diver observations indicate that the South African population of coelacanths has at least 26 individuals, mostly occupying the depth range of 104–140 m in canyons. Seventeen CTD sections collected during four cruises in 2002 and 2003 indicate the temperature range in this habitat to be similar to that found in the Comoros Islands (that is, 15–22°C cf. 15–19°C in the Comoros). However, a 2.5-month-long time series of hourly data collected by a thermistor array deployed near a known coelacanth cave in Wright Canyon indicated greater variation than anticipated, with temperature changes between 16°C and 24°C occurring in a day. Dissolved oxygen levels in this depth zone were found to range between 3.0 ml l[superscript (–1)] and 4.8 ml l[superscript (–1)] compared to 3.5 ml l[superscript (–1)] in the Comoros. The low oxygen values along this coast are a result of the shallow oxygen minimum, which becomes shallower in the southwest Indian Ocean, particularly in the Agulhas Current, than in tropical latitudes. Current velocities measured using a ship-borne ADCP in the depth range 100–140 m at Sodwana were considerably higher than those measured in the Comoros habitat (20–60 cm s[superscript (–1)] cf. 3–4 cm s[superscript (–1)]) and may be an important factor explaining the coelacanths’ occupation of the canyons found along the northern KZN shelf-break.
- Full Text:
- Date Issued: 2006
Olive Schreiner at 150: some thoughts on re-editing Cronwright's The Reinterment on Buffelskop
- Walters, Paul S, Fogg, W Jeremy M
- Authors: Walters, Paul S , Fogg, W Jeremy M
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6124 , http://hdl.handle.net/10962/d1004708
- Description: [From the introduction]: The original edition of Cronwright’s The Reinterment on Buffelskop (1983) was produced by Guy Butler and Nick Visser to commemorate the centenary of the 1883 publication of The Story of an African Farm. The Butler-Visser text was a photographic reproduction of a typed carbon copy of the first part of Cronwright’s extant diaries plus a special diary he had kept covering in detail the events of the actual reinterment. (The originals are now at the National English Literary Museum [NELM].) Butler included a comprehensive and illuminating introduction to these texts, as well as – under separate soft cover – a set of “Provisional Notes” which draw deeply on his own and his family’s accumulated knowledge of Cradock, its environs and inhabitants. In addition, Butler and Visser included two passages excised by Cronwright from the typescript of his Life of Olive Schreiner: a word picture of Charles Heathcote, and the longer account of “The Nienaber Incident” – pages which deal with the execution of three innocent men at De Aar on 19 March 1901, and Cronwright’s subsequent attempts at legal reparation for them and their families. The substantive text of the Butler-Visser edition is often difficult to read because of the method of reproduction; moreover, because it also reproduces Cronwright’s emendations (in ink) of the typescript, it is frankly uninviting. Thus, when the NELM Council proposed a publication commemorating the 150th anniversary of Olive Schreiner’s birth on 24 March 1855, it seemed appropriate that a second attempt be made to give students of Olive Schreiner’s works easier access to Cronwright’s detailed account of this “bizarre, romantic” episode. Furthermore, from the perspective of text history, the typescript of the Reinterment antedates both Cronwright’s Life and The Letters of Olive Schreiner. Parts of it are clearly Cronwright’s preliminary ‘notes towards’ his Life, and, as Butler hypothesizes, the whole of the Reinterment might have been intended as a separate (and earlier) publication. Finally, the sarcophagus on Buffelskop is one of South Africa’s more noteworthy literary shrines: while the idea of re-editing an account of Olive Schreiner’s reinterment might be thought to be a futile exercise in intellectual recycling, our intention is that both husband and wife should live again through a rediscovery of the thoughts and feelings that led them to this dramatic final resting-place.
- Full Text:
- Date Issued: 2006
- Authors: Walters, Paul S , Fogg, W Jeremy M
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6124 , http://hdl.handle.net/10962/d1004708
- Description: [From the introduction]: The original edition of Cronwright’s The Reinterment on Buffelskop (1983) was produced by Guy Butler and Nick Visser to commemorate the centenary of the 1883 publication of The Story of an African Farm. The Butler-Visser text was a photographic reproduction of a typed carbon copy of the first part of Cronwright’s extant diaries plus a special diary he had kept covering in detail the events of the actual reinterment. (The originals are now at the National English Literary Museum [NELM].) Butler included a comprehensive and illuminating introduction to these texts, as well as – under separate soft cover – a set of “Provisional Notes” which draw deeply on his own and his family’s accumulated knowledge of Cradock, its environs and inhabitants. In addition, Butler and Visser included two passages excised by Cronwright from the typescript of his Life of Olive Schreiner: a word picture of Charles Heathcote, and the longer account of “The Nienaber Incident” – pages which deal with the execution of three innocent men at De Aar on 19 March 1901, and Cronwright’s subsequent attempts at legal reparation for them and their families. The substantive text of the Butler-Visser edition is often difficult to read because of the method of reproduction; moreover, because it also reproduces Cronwright’s emendations (in ink) of the typescript, it is frankly uninviting. Thus, when the NELM Council proposed a publication commemorating the 150th anniversary of Olive Schreiner’s birth on 24 March 1855, it seemed appropriate that a second attempt be made to give students of Olive Schreiner’s works easier access to Cronwright’s detailed account of this “bizarre, romantic” episode. Furthermore, from the perspective of text history, the typescript of the Reinterment antedates both Cronwright’s Life and The Letters of Olive Schreiner. Parts of it are clearly Cronwright’s preliminary ‘notes towards’ his Life, and, as Butler hypothesizes, the whole of the Reinterment might have been intended as a separate (and earlier) publication. Finally, the sarcophagus on Buffelskop is one of South Africa’s more noteworthy literary shrines: while the idea of re-editing an account of Olive Schreiner’s reinterment might be thought to be a futile exercise in intellectual recycling, our intention is that both husband and wife should live again through a rediscovery of the thoughts and feelings that led them to this dramatic final resting-place.
- Full Text:
- Date Issued: 2006
On the correlation between annealing and variabilities in pulsed-luminescence from quartz
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
- Authors: Chithambo, Makaiko L
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6797 , http://hdl.handle.net/10962/d1003923
- Description: Properties of luminescence lifetimes in quartz related to annealing between 500 and 900ºC have been investigated. The luminescence was pulse-stimulated at 470 nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900ºC. The lifetimes decrease with annealing temperature from about 42 to 33 µѕ when the annealing temperature is increased from 500 to 900ºC. Luminescence lifetimes are most sensitive to duration of annealing at 600ºC, decreasing from 40.2 ± 0.7 µѕ by as much as 7 µѕ when the duration of annealing is changed from 10 to 60 min. However, at 800–900ºC lifetimes are essentially independent of annealing temperature at about 33 µѕ. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800ºC but not in those annealed at either 500 or 600ºC. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process.
- Full Text:
- Date Issued: 2006
Preferential electrosorption of cobalt (II) tetra-aminophthalocyanine at single-wall carbon nanotubes immobilized on a basal plane pyrolytic graphite electrode
- Ozoemena, Kenneth I, Pillay, J, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Pillay, J , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6584 , http://hdl.handle.net/10962/d1004160
- Description: This communication describes the preferential electrosorption of cobalt (II) tetra-aminophthalocyanine (CoTAPc) (rather than the expected electropolymerisation) onto a SWCNT immobilized on a basal plane pyrolytic graphite electrode (BPPGE). Cyclic voltammetric and electrochemical impedance spectroscopic data revealed that the electrosorbed CoTAPc is highly stable, well organized with comparable electron-transfer rate constant in ferricyanide solution (k[subscript app] ~ 6 × 10[superscript (−5)] cm s[superscript (−1)] order) to that of the SWNCT. Electrochemical kinetics of the electrosorbed CoTAPc yielded k[subscript s] of 0.169 s[superscript (−1)] and 832.2 s[superscript (−1)] for the cathodic and anodic reactions, respectively, indicative of different rate-determining steps for the cathodic and anodic reactions. Strong π-stacking interactions between CoTAPc and the sidewalls of the SWCNTs, with possible synergistic covalent interactions, are explained as responsible for the preferential electrosorption process. Both BPPGE-SWCNT-CoTAPc[subscript (ads)] and BPPGE-SWCNT showed comparable electrocatalytic responses towards the detection of 2-(diethylamino) ethanethiol (DEAET).
- Full Text:
- Date Issued: 2006
- Authors: Ozoemena, Kenneth I , Pillay, J , Nyokong, Tebello
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6584 , http://hdl.handle.net/10962/d1004160
- Description: This communication describes the preferential electrosorption of cobalt (II) tetra-aminophthalocyanine (CoTAPc) (rather than the expected electropolymerisation) onto a SWCNT immobilized on a basal plane pyrolytic graphite electrode (BPPGE). Cyclic voltammetric and electrochemical impedance spectroscopic data revealed that the electrosorbed CoTAPc is highly stable, well organized with comparable electron-transfer rate constant in ferricyanide solution (k[subscript app] ~ 6 × 10[superscript (−5)] cm s[superscript (−1)] order) to that of the SWNCT. Electrochemical kinetics of the electrosorbed CoTAPc yielded k[subscript s] of 0.169 s[superscript (−1)] and 832.2 s[superscript (−1)] for the cathodic and anodic reactions, respectively, indicative of different rate-determining steps for the cathodic and anodic reactions. Strong π-stacking interactions between CoTAPc and the sidewalls of the SWCNTs, with possible synergistic covalent interactions, are explained as responsible for the preferential electrosorption process. Both BPPGE-SWCNT-CoTAPc[subscript (ads)] and BPPGE-SWCNT showed comparable electrocatalytic responses towards the detection of 2-(diethylamino) ethanethiol (DEAET).
- Full Text:
- Date Issued: 2006
Professionalism and training for mass communication: challenges and opportunities for Southern Africa
- Authors: Berger, Guy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6332 , http://hdl.handle.net/10962/d1008477
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Closely linked to a critical media citizenry that can demand better of the media, is the challenge of professionalism and training in the region. Professor Guy Berger illuminates the challenges that the region faces in this regard, a key one being the ability to to match the inputs with the outcomes ... where measuring whether the quality of media products is directly linked to the inputs in training needs to be explored further.
- Full Text:
- Date Issued: 2006
- Authors: Berger, Guy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6332 , http://hdl.handle.net/10962/d1008477
- Description: [From OPENSPACE Editor Alice Kanengoni's editorial]: Closely linked to a critical media citizenry that can demand better of the media, is the challenge of professionalism and training in the region. Professor Guy Berger illuminates the challenges that the region faces in this regard, a key one being the ability to to match the inputs with the outcomes ... where measuring whether the quality of media products is directly linked to the inputs in training needs to be explored further.
- Full Text:
- Date Issued: 2006
Professor Emeritus Denis William Ewer MBE FRSSAf 1913 - 2009: biographical memoir
- Authors: Hodgson, Alan N
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6884 , http://hdl.handle.net/10962/d1011643
- Description: Denis Ewer went to University College School in London. In 1931 he entered Trinity College, Cambridge (his father had studied mathematics at Trinity) where he read for the Natural Science Tripos, obtaining a B.A. in 1934. In his second year at Cambridge he gained the nickname of 'Jakes' via a literary route (his father's nickname also had literary origins). The word 'ewer' can mean a jug, chamber pot, or jerry, and hence the progress to 'jakes', Elizabethan English for an outside lavatory. It was at Cambridge that he also met the future communist spy, Kim Philby. After graduating, Jakes Ewer moved to the University of Birmingham where he undertook his doctoral studies (graduating PhD in 1940) under H. Munro Fox. World War II, however, temporarily halted any further academic career, and during the war years he was an Experimental Officer for the Army Operational Research Group (Ministry of Supply) achieving the rank of Major. For his work, which included being a Scientific Advisor to the Chief, Air Defence Division, Supreme Headquarters Allied Expeditionary Force, he was awarded the M.B.E. (Member of the British Empire).
- Full Text:
- Date Issued: 2006
- Authors: Hodgson, Alan N
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6884 , http://hdl.handle.net/10962/d1011643
- Description: Denis Ewer went to University College School in London. In 1931 he entered Trinity College, Cambridge (his father had studied mathematics at Trinity) where he read for the Natural Science Tripos, obtaining a B.A. in 1934. In his second year at Cambridge he gained the nickname of 'Jakes' via a literary route (his father's nickname also had literary origins). The word 'ewer' can mean a jug, chamber pot, or jerry, and hence the progress to 'jakes', Elizabethan English for an outside lavatory. It was at Cambridge that he also met the future communist spy, Kim Philby. After graduating, Jakes Ewer moved to the University of Birmingham where he undertook his doctoral studies (graduating PhD in 1940) under H. Munro Fox. World War II, however, temporarily halted any further academic career, and during the war years he was an Experimental Officer for the Army Operational Research Group (Ministry of Supply) achieving the rank of Major. For his work, which included being a Scientific Advisor to the Chief, Air Defence Division, Supreme Headquarters Allied Expeditionary Force, he was awarded the M.B.E. (Member of the British Empire).
- Full Text:
- Date Issued: 2006
Re-deploying Parker, post-colonially: review essay
- Macleod, Catriona I, Wilbraham, Lindy
- Authors: Macleod, Catriona I , Wilbraham, Lindy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6275 , http://hdl.handle.net/10962/d1008275
- Description: In this paper we review two of Ian Parker’s recent books: Critical discursive psychology and Qualitative psychology: Introducing radical research. Although the books address different audiences (academics versus students) and talk to different problematics (theory versus research), taken together they represent useful resources for those wishing to take a critical stance with regards to the standard fare of psychology, to use critical theory in understanding social and psychological phenomena, and to engage in progressive research. As such, both theory and research methods appear as “tools”, and we suggest reading Parker sideways, shifting his intellectual trajectory into directions that illuminate colonial and post-colonial issues through empirical/textual application to real South African contexts. By way of illustration, we offer a post-colonial reading of Parker’s work on post-modernism. Concluding comments on tactics for a “post-colonial analysis of discourses” are offered.
- Full Text:
- Date Issued: 2006
- Authors: Macleod, Catriona I , Wilbraham, Lindy
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:6275 , http://hdl.handle.net/10962/d1008275
- Description: In this paper we review two of Ian Parker’s recent books: Critical discursive psychology and Qualitative psychology: Introducing radical research. Although the books address different audiences (academics versus students) and talk to different problematics (theory versus research), taken together they represent useful resources for those wishing to take a critical stance with regards to the standard fare of psychology, to use critical theory in understanding social and psychological phenomena, and to engage in progressive research. As such, both theory and research methods appear as “tools”, and we suggest reading Parker sideways, shifting his intellectual trajectory into directions that illuminate colonial and post-colonial issues through empirical/textual application to real South African contexts. By way of illustration, we offer a post-colonial reading of Parker’s work on post-modernism. Concluding comments on tactics for a “post-colonial analysis of discourses” are offered.
- Full Text:
- Date Issued: 2006
Recruitment behaviour in the ponerine ant, Plectroctena mandibularis F. Smith (Hymenoptera: Formicidae)
- Wilkins, K J, Harman, K, Villet, Martin H
- Authors: Wilkins, K J , Harman, K , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6887 , http://hdl.handle.net/10962/d1011647
- Description: Although workers of Plectroctena mandibularis laid trails with their stings while foraging, the trails appeared to be for individual orientation, because they never recruited nestmates to prey. However, both workers and queens laid trails when recruiting nestmates of either caste to new nest sites. During trail-laying, fluted hairs on the posterior edge of tergite VI were dragged along the ground, presumably applying a pheromone to the substrate. Anatomical and behavioural evidence suggests that pygidial gland secretions moved from the intersegmental pygidial gland between tergites VI and VII into a fingerprint-like, lamellar cuticular reservoir on the pygidium, and from there via the hairs to the substrate. These results suggest that recruitment may be crucial to moving nests but of value only to certain types of foraging, and that recruitment might even have originated in the Formicidae in the context of colony relocation, and then secondarily evolved to assist foraging.
- Full Text:
- Date Issued: 2006
- Authors: Wilkins, K J , Harman, K , Villet, Martin H
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6887 , http://hdl.handle.net/10962/d1011647
- Description: Although workers of Plectroctena mandibularis laid trails with their stings while foraging, the trails appeared to be for individual orientation, because they never recruited nestmates to prey. However, both workers and queens laid trails when recruiting nestmates of either caste to new nest sites. During trail-laying, fluted hairs on the posterior edge of tergite VI were dragged along the ground, presumably applying a pheromone to the substrate. Anatomical and behavioural evidence suggests that pygidial gland secretions moved from the intersegmental pygidial gland between tergites VI and VII into a fingerprint-like, lamellar cuticular reservoir on the pygidium, and from there via the hairs to the substrate. These results suggest that recruitment may be crucial to moving nests but of value only to certain types of foraging, and that recruitment might even have originated in the Formicidae in the context of colony relocation, and then secondarily evolved to assist foraging.
- Full Text:
- Date Issued: 2006
Regional calibration of the Pitman model for the Okavango River
- Hughes, Denis A, Andersson, L, Wilk, J, Savenije, H H G
- Authors: Hughes, Denis A , Andersson, L , Wilk, J , Savenije, H H G
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7085 , http://hdl.handle.net/10962/d1012344
- Description: This paper reports on the application of a monthly rainfall-runoff model for the Okavango River Basin. Streamflow is mainly generated in Angola where the Cuito and Cubango rivers arise. They then join and cross the Namibia/Angola border, flowing into the Okavango wetland in Botswana. The model is a modified version of the Pitman model, including more explicit ground and surface water interactions. Significant limitations in access to climatological data, and lack of sufficiently long records of observed flow for the eastern sub-basins represent great challenges to model calibration. The majority of the runoff is generated in the wetter headwater tributaries, while the lower sub-basins are dominated by channel loss processes with very little incremental flow contributions, even during wet years. The western tributaries show significantly higher seasonal variation in flow, compared to the baseflow dominated eastern tributaries: observations that are consistent with their geological differences. The basin was sub-divided into 24 sub-basins, of which 18 have gauging stations at their outlet. Satisfactory simulations were achieved with sub-basin parameter value differences that correspond to the spatial variability in basin physiographic characteristics. The limited length of historical rainfall and river discharge data over Angola precluded the use of a split sample calibration/validation test. However, satellite generated rainfall data, revised to reflect the same frequency characteristics as the historical rainfall data, were used to validate the model against the available downstream flow data during the 1990s. The overall conclusion is that the model, in spite of the limited data access, adequately represents the hydrological response of the basin and that it can be used to assess the impact of future development scenarios.
- Full Text:
- Date Issued: 2006
- Authors: Hughes, Denis A , Andersson, L , Wilk, J , Savenije, H H G
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7085 , http://hdl.handle.net/10962/d1012344
- Description: This paper reports on the application of a monthly rainfall-runoff model for the Okavango River Basin. Streamflow is mainly generated in Angola where the Cuito and Cubango rivers arise. They then join and cross the Namibia/Angola border, flowing into the Okavango wetland in Botswana. The model is a modified version of the Pitman model, including more explicit ground and surface water interactions. Significant limitations in access to climatological data, and lack of sufficiently long records of observed flow for the eastern sub-basins represent great challenges to model calibration. The majority of the runoff is generated in the wetter headwater tributaries, while the lower sub-basins are dominated by channel loss processes with very little incremental flow contributions, even during wet years. The western tributaries show significantly higher seasonal variation in flow, compared to the baseflow dominated eastern tributaries: observations that are consistent with their geological differences. The basin was sub-divided into 24 sub-basins, of which 18 have gauging stations at their outlet. Satisfactory simulations were achieved with sub-basin parameter value differences that correspond to the spatial variability in basin physiographic characteristics. The limited length of historical rainfall and river discharge data over Angola precluded the use of a split sample calibration/validation test. However, satellite generated rainfall data, revised to reflect the same frequency characteristics as the historical rainfall data, were used to validate the model against the available downstream flow data during the 1990s. The overall conclusion is that the model, in spite of the limited data access, adequately represents the hydrological response of the basin and that it can be used to assess the impact of future development scenarios.
- Full Text:
- Date Issued: 2006
Repositioning Renaissance studies in South Africa: strategic thinking or 'business-as-usual
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006
- Authors: Wright, Laurence
- Date: 2006
- Language: English
- Type: Article
- Identifier: vital:7054 , http://hdl.handle.net/10962/d1007415
- Description: Increasingly, in many leading South African tertiary departments of literature, early modern studies have a fairly slim hold on the core curriculum. More and more, departmental offerings concentrate on nineteenth and twentieth century literature, perhaps in the belief either that today’s students are so poorly prepared that they will never be able to cope with the mental shifts necessary to appreciate pre-industrial literature and its language, or, worse, that nothing before the C19 colonial incursion into South Africa can really matter very much to undergraduates. Whatever the reason, in such departments, it is no longer possible to get to grips with the contribution of the renaissance to the formation of the modern world. The significance of the broader nomenclature, early modern studies, doesn’t appear to strike home, especially the point that, if students want to understand the world we live in, they have to know this period particularly well. Indeed, they need to have some idea of the interaction between early modern Europe and the literature and ideas of the ancient civilizations of Rome and Greece. If we fail them in this regard, as I believe we are doing to an increasing extent, the result will be generations of intellectual sleepwalkers, denizens of mental landscapes they are responding to, or ‘reading’, in terms of an inner life unaware of important historical continuities and disjunctions; cut off, moreover, from understanding essential features of modernity.
- Full Text:
- Date Issued: 2006