Curiosity first, applications later
- Berold, Robert, Limson, Janice L
- Authors: Berold, Robert , Limson, Janice L
- Date: 2009
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7188 , http://hdl.handle.net/10962/d1006281 , http://www.sajs.co.za/sites/default/files/publications/pdf/1-4-1-PB.pdf , Nyokong, Tebello
- Description: Tebello Nyokong speaks to Robert Berold and Janice Limson about her career as a chemist. Tebello Nyokong, who holds a research chair in medicinal chemistry and nanotechnology at Rhodes University, has become the first South African scientist to win the L’Oreal-UNESCO award for women in science, in the physical sciences. Only one laureate is selected from each of five world regions, and Nyokong is the 2009 laureate for Africa and the Arab states. She and the winners from the other four regions travel to Paris in March to each accept the award and a generous prize of close to R1 million. Nyokong now heads the new Nanotechnology Innovation Centre for medical sensors: the biggest single research investment in the history of Rhodes. Linked to other nanotechnology centres in the country, it is designed to bridge the gap between research and the market.
- Full Text:
- Date Issued: 2009
- Authors: Berold, Robert , Limson, Janice L
- Date: 2009
- Subjects: Nyokong, Tebello
- Language: English
- Type: Article , text
- Identifier: vital:7188 , http://hdl.handle.net/10962/d1006281 , http://www.sajs.co.za/sites/default/files/publications/pdf/1-4-1-PB.pdf , Nyokong, Tebello
- Description: Tebello Nyokong speaks to Robert Berold and Janice Limson about her career as a chemist. Tebello Nyokong, who holds a research chair in medicinal chemistry and nanotechnology at Rhodes University, has become the first South African scientist to win the L’Oreal-UNESCO award for women in science, in the physical sciences. Only one laureate is selected from each of five world regions, and Nyokong is the 2009 laureate for Africa and the Arab states. She and the winners from the other four regions travel to Paris in March to each accept the award and a generous prize of close to R1 million. Nyokong now heads the new Nanotechnology Innovation Centre for medical sensors: the biggest single research investment in the history of Rhodes. Linked to other nanotechnology centres in the country, it is designed to bridge the gap between research and the market.
- Full Text:
- Date Issued: 2009
Effect of laundry activities on in-stream concentrations of linear alkylbenzene sulfonate in a small rural South African river
- Gordon, Andrew K, Muller, Wilhelmine J, Gysman, N, Marshall, S J, Sparham, C J, O'Connor, S M, Whelan, M J
- Authors: Gordon, Andrew K , Muller, Wilhelmine J , Gysman, N , Marshall, S J , Sparham, C J , O'Connor, S M , Whelan, M J
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7094 , http://hdl.handle.net/10962/d1012427
- Description: In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L− 1) but were generally very low (< 11 µg L− 1) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.
- Full Text:
- Date Issued: 2009
- Authors: Gordon, Andrew K , Muller, Wilhelmine J , Gysman, N , Marshall, S J , Sparham, C J , O'Connor, S M , Whelan, M J
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7094 , http://hdl.handle.net/10962/d1012427
- Description: In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L− 1) but were generally very low (< 11 µg L− 1) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.
- Full Text:
- Date Issued: 2009
A recurrent neural network approach to quantitatively studying solar wind effects on TEC derived from GPS; preliminary results
- Habarulema, John B, McKinnell, Lee-Anne, Opperman, Ben D L
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6813 , http://hdl.handle.net/10962/d1004323
- Description: This paper attempts to describe the search for the parameter(s) to represent solar wind effects in Global Positioning System total electron content (GPS TEC) modelling using the technique of neural networks (NNs). A study is carried out by including solar wind velocity (Vsw), proton number density (Np) and the Bz component of the interplanetary magnetic field (IMF Bz) obtained from the Advanced Composition Explorer (ACE) satellite as separate inputs to the NN each along with day number of the year (DN), hour (HR), a 4-month running mean of the daily sunspot number (R4) and the running mean of the previous eight 3-hourly magnetic A index values (A8). Hourly GPS TEC values derived from a dual frequency receiver located at Sutherland (32.38° S, 20.81° E), South Africa for 8 years (2000–2007) have been used to train the Elman neural network (ENN) and the result has been used to predict TEC variations for a GPS station located at Cape Town (33.95° S, 18.47° E). Quantitative results indicate that each of the parameters considered may have some degree of influence on GPS TEC at certain periods although a decrease in prediction accuracy is also observed for some parameters for different days and seasons. It is also evident that there is still a difficulty in predicting TEC values during disturbed conditions. The improvements and degradation in prediction accuracies are both close to the benchmark values which lends weight to the belief that diurnal, seasonal, solar and magnetic variabilities may be the major determinants of TEC variability.
- Full Text:
- Date Issued: 2009
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6813 , http://hdl.handle.net/10962/d1004323
- Description: This paper attempts to describe the search for the parameter(s) to represent solar wind effects in Global Positioning System total electron content (GPS TEC) modelling using the technique of neural networks (NNs). A study is carried out by including solar wind velocity (Vsw), proton number density (Np) and the Bz component of the interplanetary magnetic field (IMF Bz) obtained from the Advanced Composition Explorer (ACE) satellite as separate inputs to the NN each along with day number of the year (DN), hour (HR), a 4-month running mean of the daily sunspot number (R4) and the running mean of the previous eight 3-hourly magnetic A index values (A8). Hourly GPS TEC values derived from a dual frequency receiver located at Sutherland (32.38° S, 20.81° E), South Africa for 8 years (2000–2007) have been used to train the Elman neural network (ENN) and the result has been used to predict TEC variations for a GPS station located at Cape Town (33.95° S, 18.47° E). Quantitative results indicate that each of the parameters considered may have some degree of influence on GPS TEC at certain periods although a decrease in prediction accuracy is also observed for some parameters for different days and seasons. It is also evident that there is still a difficulty in predicting TEC values during disturbed conditions. The improvements and degradation in prediction accuracies are both close to the benchmark values which lends weight to the belief that diurnal, seasonal, solar and magnetic variabilities may be the major determinants of TEC variability.
- Full Text:
- Date Issued: 2009
Towards a GPS-based TEC prediction model for Southern Africa with feed forward networks
- Habarulema, John B, McKinnell, Lee-Anne, Opperman, Ben D L
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6806 , http://hdl.handle.net/10962/d1004192
- Description: In this paper, first results from a national Global Positioning System (GPS) based total electron content (TEC) prediction model over South Africa are presented. Data for 10 GPS receiver stations distributed through out the country were used to train a feed forward neural network (NN) over an interval of at most five years. In the NN training, validating and testing processes, five factors which are well known to influence TEC variability namely diurnal variation, seasonal variation, magnetic activity, solar activity and the geographic position of the GPS receivers were included in the NN model. The database consisted of 1-min data and therefore the NN model developed can be used to forecast TEC values 1 min in advance. Results from the NN national model (NM) were compared with hourly TEC values generated by the earlier developed NN single station models (SSMs) at Sutherland (32.38°S, 20.81°E) and Springbok (29.67°S, 17.88°E), to predict TEC variations over the Cape Town (33.95°S, 18.47°E) and Upington (28.41°S, 21.26°E) stations, respectively, during equinoxes and solstices. This revealed that, on average, the NM led to an improvement in TEC prediction accuracy compared to the SSMs for the considered testing periods.
- Full Text:
- Date Issued: 2009
- Authors: Habarulema, John B , McKinnell, Lee-Anne , Opperman, Ben D L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6806 , http://hdl.handle.net/10962/d1004192
- Description: In this paper, first results from a national Global Positioning System (GPS) based total electron content (TEC) prediction model over South Africa are presented. Data for 10 GPS receiver stations distributed through out the country were used to train a feed forward neural network (NN) over an interval of at most five years. In the NN training, validating and testing processes, five factors which are well known to influence TEC variability namely diurnal variation, seasonal variation, magnetic activity, solar activity and the geographic position of the GPS receivers were included in the NN model. The database consisted of 1-min data and therefore the NN model developed can be used to forecast TEC values 1 min in advance. Results from the NN national model (NM) were compared with hourly TEC values generated by the earlier developed NN single station models (SSMs) at Sutherland (32.38°S, 20.81°E) and Springbok (29.67°S, 17.88°E), to predict TEC variations over the Cape Town (33.95°S, 18.47°E) and Upington (28.41°S, 21.26°E) stations, respectively, during equinoxes and solstices. This revealed that, on average, the NM led to an improvement in TEC prediction accuracy compared to the SSMs for the considered testing periods.
- Full Text:
- Date Issued: 2009
Apis florea in Jordan: source of the founder population
- Haddad, N, Fuchs, S, Hepburn, H Randall, Radloff, Sarah E
- Authors: Haddad, N , Fuchs, S , Hepburn, H Randall , Radloff, Sarah E
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6844 , http://hdl.handle.net/10962/d1011047
- Description: A recent isolated population of Apis florea has been reported from Aqaba in Jordan at the Red Sea, consisting of numerous colonies within a still limited range which apparently is expanding. This region is about 1500 km apart from its next occurrences in Sudan where it had been introduced and first detected in 1985 and about 2000 km apart from its next natural occurrences in Iran and Oman. These bees apparently have been imported by human transport, most likely by ship. This new location thus represents a major jump in the progression of the species still to fill a wide area of possible locations offering adequate living conditions. Here we attempt to track the possible origin of this new population by morphometric methods. This analysis indicated closest relation to A. florea from Oman, thus being the most likely source of this population.
- Full Text:
- Date Issued: 2009
- Authors: Haddad, N , Fuchs, S , Hepburn, H Randall , Radloff, Sarah E
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6844 , http://hdl.handle.net/10962/d1011047
- Description: A recent isolated population of Apis florea has been reported from Aqaba in Jordan at the Red Sea, consisting of numerous colonies within a still limited range which apparently is expanding. This region is about 1500 km apart from its next occurrences in Sudan where it had been introduced and first detected in 1985 and about 2000 km apart from its next natural occurrences in Iran and Oman. These bees apparently have been imported by human transport, most likely by ship. This new location thus represents a major jump in the progression of the species still to fill a wide area of possible locations offering adequate living conditions. Here we attempt to track the possible origin of this new population by morphometric methods. This analysis indicated closest relation to A. florea from Oman, thus being the most likely source of this population.
- Full Text:
- Date Issued: 2009
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
A preliminary survey of the estuaries on the south coast of South Africa, Robberg Peninsula - Cape St Francis, with particular reference to the fish fauna : ecological overview article
- James, Nicola Caroline, Harrison, T D
- Authors: James, Nicola Caroline , Harrison, T D
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7144 , http://hdl.handle.net/10962/d1011842
- Description: A basic ichthyofaunal and physico-chemical survey of the coastal outlets on the south coast of South Africa (Robberg Peninsula to Cape St Francis) was undertaken during November 1994 and September 1995. Some 27 systems were identified along this stretch of coast and of these, 48% (Brak, Helpmekaars, Klip, Witels, Geelhoutbos, Kleinbos, Bruglaagte, Langbos, Sanddrif, Eerste, Boskloof, Kaapsedrif and Klipdrif [Wes]) comprised the inlets of coastal streams that offer little habitat for fishes, 26% (Sout, Bloukrans, Lottering, Elandsbos, Storms, Elands and Groot [Oos]) are located within deeply incised valleys within the Tsitsikamma region and provide limited littoral habitat for estuary-associated fishes; 26% of the systems (Piesang, Keurbooms, Matjies, Groot [Wes], Tsitsikamma, Klipdrif [Oos], Slang) appear to serve some estuarine function for both marine migrant and resident species although some of these may also be limited due to their small size and infrequent connection with the sea. This study serves to emphasize the ecological importance of these latter estuaries within this coastal sector.
- Full Text:
- Date Issued: 2009
- Authors: James, Nicola Caroline , Harrison, T D
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7144 , http://hdl.handle.net/10962/d1011842
- Description: A basic ichthyofaunal and physico-chemical survey of the coastal outlets on the south coast of South Africa (Robberg Peninsula to Cape St Francis) was undertaken during November 1994 and September 1995. Some 27 systems were identified along this stretch of coast and of these, 48% (Brak, Helpmekaars, Klip, Witels, Geelhoutbos, Kleinbos, Bruglaagte, Langbos, Sanddrif, Eerste, Boskloof, Kaapsedrif and Klipdrif [Wes]) comprised the inlets of coastal streams that offer little habitat for fishes, 26% (Sout, Bloukrans, Lottering, Elandsbos, Storms, Elands and Groot [Oos]) are located within deeply incised valleys within the Tsitsikamma region and provide limited littoral habitat for estuary-associated fishes; 26% of the systems (Piesang, Keurbooms, Matjies, Groot [Wes], Tsitsikamma, Klipdrif [Oos], Slang) appear to serve some estuarine function for both marine migrant and resident species although some of these may also be limited due to their small size and infrequent connection with the sea. This study serves to emphasize the ecological importance of these latter estuaries within this coastal sector.
- Full Text:
- Date Issued: 2009
The evaluation of Eudragit microcapsules manufactured by solvent evaporation using USP Apparatus 1
- Khamanga, Sandile M, Parfitt, Natalie R, Nyamuzhiwa, Tsitsi, Haidula, Hendrina, Walker, Roderick B
- Authors: Khamanga, Sandile M , Parfitt, Natalie R , Nyamuzhiwa, Tsitsi , Haidula, Hendrina , Walker, Roderick B
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6389 , http://hdl.handle.net/10962/d1006310
- Description: The objectives of this study were to prepare microcapsules containing verapamil and propranolol and to evaluate the kinetics and mechanism of drug release from the microcapsules using USP Apparatus 1. The effects of polymer concentration and polymer type on the cumulative amount of drug released were evaluated. The microcapsules were manufactured using Eudragit RS and RL polymers by solvent evaporation with the ultimate aim of prolonging drug release. Twenty-four formulations were prepared using different drug/polymer ratios. The effects of polymer type and polymer/drug ratios on the size, flow properties, surface morphology, and the release characteristics of the microcapsules were examined. The effects of drug inclusion methods on drug loading, encapsulation efficiency, and release properties of the complex microcapsules were also investigated. The formulations containing drug/polymer ratio 1:4 (w/w) were the most appropriate with respect to encapsulation efficiency (70%), flow properties (HR = 1.2), drug loading (15–20%), and drug release characteristics, in all cases. The release kinetics from the different formulations followed mainly a diffusion-controlled mechanism.
- Full Text:
- Date Issued: 2009
- Authors: Khamanga, Sandile M , Parfitt, Natalie R , Nyamuzhiwa, Tsitsi , Haidula, Hendrina , Walker, Roderick B
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6389 , http://hdl.handle.net/10962/d1006310
- Description: The objectives of this study were to prepare microcapsules containing verapamil and propranolol and to evaluate the kinetics and mechanism of drug release from the microcapsules using USP Apparatus 1. The effects of polymer concentration and polymer type on the cumulative amount of drug released were evaluated. The microcapsules were manufactured using Eudragit RS and RL polymers by solvent evaporation with the ultimate aim of prolonging drug release. Twenty-four formulations were prepared using different drug/polymer ratios. The effects of polymer type and polymer/drug ratios on the size, flow properties, surface morphology, and the release characteristics of the microcapsules were examined. The effects of drug inclusion methods on drug loading, encapsulation efficiency, and release properties of the complex microcapsules were also investigated. The formulations containing drug/polymer ratio 1:4 (w/w) were the most appropriate with respect to encapsulation efficiency (70%), flow properties (HR = 1.2), drug loading (15–20%), and drug release characteristics, in all cases. The release kinetics from the different formulations followed mainly a diffusion-controlled mechanism.
- Full Text:
- Date Issued: 2009
Disjunctions in the Diptera (Insecta) fauna of the Mediterranean Province and southern Africa and a discussion of biogeographical considerations : ecological overview article
- Kirk-Spriggs, A H, McGregor, Gillian K
- Authors: Kirk-Spriggs, A H , McGregor, Gillian K
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6880 , http://hdl.handle.net/10962/d1011636
- Description: This paper explores disjunctions in the Diptera fauna of the Mediterranean Province and southern Africa, drawing from eight families of Diptera, the more ancient Psychodidae and Vermileonidae, and the more recent Acroceridae, Asilidae, Bombyliidae, Dolichopodidae, Pipunculidae and Sciomyzidae. Information from recent published revisions is geo-referenced and plotted onto maps using GIS software. These distribution patterns are interpreted and probable means and routes of dispersal between the two regions are discussed. The concept of an Afrotropical sub-Saharan boundary is outlined and it is argued that although the vast, arid and virtually abiotic Sahara acts as a barrier to dispersal today, relict floral and faunal populations of Mediterranean provincial origin still occur on the Hoggar and Tibesti Mountains of the central Sahara, indicating that the aridification of the Sahara is a very recent event. The presence of extensive palaeolakes formerly covering ca 10% of the present-day Sahara is regarded as evidence in support of this hypothesis. These lakes and their associated catchments, situated in basins between the central Saharan mountains, could clearly have acted as a humid route of dispersal as recently as 4000 BP, when these lakes began to recede, and this route is here regarded as a "central high Africa corridor"; a filter-bridge between the Mediterranean Province and southern Africa. Examples of Mediterranean provincial species of Ephydridae and the muscid genus Lispe Latreille, 1796, occurring as far south as the AÏr Massif in northern Niger are cited as examples of relict montane Diptera of Mediterranean provincial origin in the southern Hoggar Mountains; these groups being associated with the margins of standing water. Balinsky's (1962) concept of an "arid corridor" is also re-examined, using examples from the larger, less mobile Diptera, and it is concluded that such a pattern may not be the result of aridity, but represent an "eastern high Africa corridor", broadly corresponding to the "African Supers well". Other perceived distribution pathways between the Holarctic and Afrotropical Regions are mapped. Anemochore dispersal is considered, and the extent of the Afrotropical Region is discussed. Mediterranean tectonic evolution on both a globe of constant size and on a smaller Jurassic globe is also considered. It is concluded that if all the transitional zones between the zoogeographical regions are to be given more-or-less equivalent treatment, we must avoid setting boundaries based on earlier faunal distributions. For this reason the current boundary between the Palaearctic and Afrotropical Regions, arbitrary as it is, should be retained, despite evidence suggesting recent continuity between sub-Saharan Africa, North Africa and the Arabian Peninsula, corresponding broadly to the African and Arabian lithospheric plates.
- Full Text:
- Date Issued: 2009
- Authors: Kirk-Spriggs, A H , McGregor, Gillian K
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6880 , http://hdl.handle.net/10962/d1011636
- Description: This paper explores disjunctions in the Diptera fauna of the Mediterranean Province and southern Africa, drawing from eight families of Diptera, the more ancient Psychodidae and Vermileonidae, and the more recent Acroceridae, Asilidae, Bombyliidae, Dolichopodidae, Pipunculidae and Sciomyzidae. Information from recent published revisions is geo-referenced and plotted onto maps using GIS software. These distribution patterns are interpreted and probable means and routes of dispersal between the two regions are discussed. The concept of an Afrotropical sub-Saharan boundary is outlined and it is argued that although the vast, arid and virtually abiotic Sahara acts as a barrier to dispersal today, relict floral and faunal populations of Mediterranean provincial origin still occur on the Hoggar and Tibesti Mountains of the central Sahara, indicating that the aridification of the Sahara is a very recent event. The presence of extensive palaeolakes formerly covering ca 10% of the present-day Sahara is regarded as evidence in support of this hypothesis. These lakes and their associated catchments, situated in basins between the central Saharan mountains, could clearly have acted as a humid route of dispersal as recently as 4000 BP, when these lakes began to recede, and this route is here regarded as a "central high Africa corridor"; a filter-bridge between the Mediterranean Province and southern Africa. Examples of Mediterranean provincial species of Ephydridae and the muscid genus Lispe Latreille, 1796, occurring as far south as the AÏr Massif in northern Niger are cited as examples of relict montane Diptera of Mediterranean provincial origin in the southern Hoggar Mountains; these groups being associated with the margins of standing water. Balinsky's (1962) concept of an "arid corridor" is also re-examined, using examples from the larger, less mobile Diptera, and it is concluded that such a pattern may not be the result of aridity, but represent an "eastern high Africa corridor", broadly corresponding to the "African Supers well". Other perceived distribution pathways between the Holarctic and Afrotropical Regions are mapped. Anemochore dispersal is considered, and the extent of the Afrotropical Region is discussed. Mediterranean tectonic evolution on both a globe of constant size and on a smaller Jurassic globe is also considered. It is concluded that if all the transitional zones between the zoogeographical regions are to be given more-or-less equivalent treatment, we must avoid setting boundaries based on earlier faunal distributions. For this reason the current boundary between the Palaearctic and Afrotropical Regions, arbitrary as it is, should be retained, despite evidence suggesting recent continuity between sub-Saharan Africa, North Africa and the Arabian Peninsula, corresponding broadly to the African and Arabian lithospheric plates.
- Full Text:
- Date Issued: 2009
Drawing Lines in the Sand: AM v RM 2010 2 SA 223 (ECP)
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54107 , vital:26391 , http://www.ufh.ac.za/speculumjuris/files/pdf/SpeculumJuris_2009_Part_2.pdf
- Description: Judge Elna Revelas’s decision in the case of Mohamed v Mohamed 1 may be described as one of those run-of-the-mill applications in terms of rule 43 which are routinely heard on motion court days in any one of our high courts across the country. This case note suggests that her decision belies such a description. Instead, this note suggests that her decision marks a move away from existing jurisprudence on Muslim marriages in a way which may undermine, rather than promote, the recognition and respect for the marriage institutions of different religious systems and beliefs. I tentatively suggest that by granting the rule 43 application the court may have effectively imposed civil marriage obligations on a religious marriage even though the parties had not concluded a marriage in terms of the Marriage Act.2 As such, the decision has potentially radical consequences for parties in Muslim marriages and highlights the complex issues that courts have had to face in the last two decades without any guiding legislation. In order to understand the judgment properly, its context has to be considered. This context includes (1) the numerous judgments extending protection to women in Muslim marriages in the last two decades against the backdrop of the coming into effect of the Constitution of the Republic of South Africa, 1996; and (2) the application by the Women’s Legal Centre Trust (hereafter “WLCT”) to the Constitutional Court to force the President and Parliament to enact legislation to recognise and protect Muslim marriages.
- Full Text:
- Date Issued: 2009
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54107 , vital:26391 , http://www.ufh.ac.za/speculumjuris/files/pdf/SpeculumJuris_2009_Part_2.pdf
- Description: Judge Elna Revelas’s decision in the case of Mohamed v Mohamed 1 may be described as one of those run-of-the-mill applications in terms of rule 43 which are routinely heard on motion court days in any one of our high courts across the country. This case note suggests that her decision belies such a description. Instead, this note suggests that her decision marks a move away from existing jurisprudence on Muslim marriages in a way which may undermine, rather than promote, the recognition and respect for the marriage institutions of different religious systems and beliefs. I tentatively suggest that by granting the rule 43 application the court may have effectively imposed civil marriage obligations on a religious marriage even though the parties had not concluded a marriage in terms of the Marriage Act.2 As such, the decision has potentially radical consequences for parties in Muslim marriages and highlights the complex issues that courts have had to face in the last two decades without any guiding legislation. In order to understand the judgment properly, its context has to be considered. This context includes (1) the numerous judgments extending protection to women in Muslim marriages in the last two decades against the backdrop of the coming into effect of the Constitution of the Republic of South Africa, 1996; and (2) the application by the Women’s Legal Centre Trust (hereafter “WLCT”) to the Constitutional Court to force the President and Parliament to enact legislation to recognise and protect Muslim marriages.
- Full Text:
- Date Issued: 2009
'Here's to you, Mrs Robinson' : peculiarities and paragraph 29 in determining the treatment of domestic partnerships
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: vital:26388 , http://hdl.handle.net/10962/54083
- Description: There is always need of persons not only to discover new truths, and point out when what were once truths are true no longer, but also to commence new practices, and set the example of more enlightened conduct. The law is one of the important architects of social norms. At times, it can be a tool to solve problems, eradicate inequalities, and advance the rights of the disadvantaged. At other times, the law is an anchor and a constraint upon social and ideological advances. With regards to equality and non-traditional partnerships, it seems that law falls into this latter category.
- Full Text:
- Date Issued: 2009
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: vital:26388 , http://hdl.handle.net/10962/54083
- Description: There is always need of persons not only to discover new truths, and point out when what were once truths are true no longer, but also to commence new practices, and set the example of more enlightened conduct. The law is one of the important architects of social norms. At times, it can be a tool to solve problems, eradicate inequalities, and advance the rights of the disadvantaged. At other times, the law is an anchor and a constraint upon social and ideological advances. With regards to equality and non-traditional partnerships, it seems that law falls into this latter category.
- Full Text:
- Date Issued: 2009
'Fetal "rights"? The need for a unified approach to the fetus in the context of feticide'
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54163 , vital:26397 , https://store.lexisnexis.co.za/products/tydskrif-vir-hedendaagse-romeinshollandse-reg-journal-of-contemporary-romandutch-law-skuZASKU9780409079241/details
- Description: The issues of fetal protection, fetal rights and the status of unborn life have been debated on a variety of levels in a variety of disciplines over the past centuries. One needs only think of John Milton who asked the “hard” question: “For man to tell how human life began / Is hard: for who himself beginning knew?” (Paradise lost (1667) Bk 8 251–252). While the issue of fetal rights most often arises in abortion debates, the issue of fetal rights in the context of feticide has received scant attention in South Africa. (For a thought-provoking general discussion of fetal rights, see Du Plessis “Jurisprudential reflections on the status of unborn life” 1990 TSAR 44; Van Niekerk (ed) The status of prenatal life (1991) and Kahn (ed) The sanctity of human life (1983).) This note seeks to initiate a discussion on the current legal position in South Africa in respect of feticide.
- Full Text:
- Date Issued: 2009
- Authors: Kruuse, Helen
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: http://hdl.handle.net/10962/54163 , vital:26397 , https://store.lexisnexis.co.za/products/tydskrif-vir-hedendaagse-romeinshollandse-reg-journal-of-contemporary-romandutch-law-skuZASKU9780409079241/details
- Description: The issues of fetal protection, fetal rights and the status of unborn life have been debated on a variety of levels in a variety of disciplines over the past centuries. One needs only think of John Milton who asked the “hard” question: “For man to tell how human life began / Is hard: for who himself beginning knew?” (Paradise lost (1667) Bk 8 251–252). While the issue of fetal rights most often arises in abortion debates, the issue of fetal rights in the context of feticide has received scant attention in South Africa. (For a thought-provoking general discussion of fetal rights, see Du Plessis “Jurisprudential reflections on the status of unborn life” 1990 TSAR 44; Van Niekerk (ed) The status of prenatal life (1991) and Kahn (ed) The sanctity of human life (1983).) This note seeks to initiate a discussion on the current legal position in South Africa in respect of feticide.
- Full Text:
- Date Issued: 2009
Danger and disease in sex education : the saturation of ‘adolescence’ with colonialist assumptions
- Authors: Macleod, Catriona I
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: vital:6252 , http://hdl.handle.net/10962/d1007870
- Description: The United Nations Development Programme’s Millennium project argues for the importance of sexual and reproductive health in the achievement of all Millennium Development Goals. Sex education programmes, aimed principally at the youth, are thus emphasised and are in line with the specific Millennium Development Goals of reducing the incidence of HIV and improving maternal health. In this paper I analyse recent South African sex education and Life Orientation (a learning area containing sex education) manuals. Danger and disease feature as guiding metaphors for these manuals, with early reproduction and abortion being depicted as wholly deleterious and non-normative relationships leading to disease. I argue, firstly, that these renditions ignore well-designed comparative research that calls into questions the easy assumption of negative consequences accompanying ‘teenage pregnancy’ and abortion, and, secondly, that the persistence of danger and disease in sex education programmes is premised on a discourse of ‘adolescence’. ‘Adolescence’ as a concept is always already saturated with the colonialist foundation of phylogeny re-capitulating ontogeny. Individual development is interweaved with collective development with the threat of degeneration implied in both. This interweaving allows for the instrumentalist goal of sex education in which social changes are sought through changing individuals’ sexual attitudes and behaviour.
- Full Text:
- Date Issued: 2009
- Authors: Macleod, Catriona I
- Date: 2009
- Language: English
- Type: Article , text
- Identifier: vital:6252 , http://hdl.handle.net/10962/d1007870
- Description: The United Nations Development Programme’s Millennium project argues for the importance of sexual and reproductive health in the achievement of all Millennium Development Goals. Sex education programmes, aimed principally at the youth, are thus emphasised and are in line with the specific Millennium Development Goals of reducing the incidence of HIV and improving maternal health. In this paper I analyse recent South African sex education and Life Orientation (a learning area containing sex education) manuals. Danger and disease feature as guiding metaphors for these manuals, with early reproduction and abortion being depicted as wholly deleterious and non-normative relationships leading to disease. I argue, firstly, that these renditions ignore well-designed comparative research that calls into questions the easy assumption of negative consequences accompanying ‘teenage pregnancy’ and abortion, and, secondly, that the persistence of danger and disease in sex education programmes is premised on a discourse of ‘adolescence’. ‘Adolescence’ as a concept is always already saturated with the colonialist foundation of phylogeny re-capitulating ontogeny. Individual development is interweaved with collective development with the threat of degeneration implied in both. This interweaving allows for the instrumentalist goal of sex education in which social changes are sought through changing individuals’ sexual attitudes and behaviour.
- Full Text:
- Date Issued: 2009
Seeing is natural, but viewing is not: teaching visual literacy in a rural classroom
- Mbelani, Madeyandile, Murray, Sarah R
- Authors: Mbelani, Madeyandile , Murray, Sarah R
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7022 , http://hdl.handle.net/10962/d1007203
- Description: This paper reports on a collaborative action research case study into Grade 10 teaching and learning of visual literacy in a rural high school into the Eastern Cape, South Africa. Visual literacy is a new aspect that has been incorporated in English First Additional Language National Curriculum Statement (Grade 10-12), which has been implemented in Grade 10 from 2006. With the aim of gaining knowledge and improving performance in visual literacy, I designed a unit of lessons, which exposed learners to visual grammar and visual texts and I collected data around the implementation of the lesson unit as evidenced by journal writing, interviews and non-participant observation. The data revealed that visual literacy could be taught meaningfully in a rural high school as the learners could identify, cut, paste and critically discuss elements of visual language and they finally designed their own advertisements in groups. However, the following factors emerged as hindrances to the successful teaching of visual literacy in this case: lack of resources; learners' lack of a foundation in visual literacy from Grades 7-9; and problems revolving around time management and pacing.
- Full Text:
- Date Issued: 2009
- Authors: Mbelani, Madeyandile , Murray, Sarah R
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:7022 , http://hdl.handle.net/10962/d1007203
- Description: This paper reports on a collaborative action research case study into Grade 10 teaching and learning of visual literacy in a rural high school into the Eastern Cape, South Africa. Visual literacy is a new aspect that has been incorporated in English First Additional Language National Curriculum Statement (Grade 10-12), which has been implemented in Grade 10 from 2006. With the aim of gaining knowledge and improving performance in visual literacy, I designed a unit of lessons, which exposed learners to visual grammar and visual texts and I collected data around the implementation of the lesson unit as evidenced by journal writing, interviews and non-participant observation. The data revealed that visual literacy could be taught meaningfully in a rural high school as the learners could identify, cut, paste and critically discuss elements of visual language and they finally designed their own advertisements in groups. However, the following factors emerged as hindrances to the successful teaching of visual literacy in this case: lack of resources; learners' lack of a foundation in visual literacy from Grades 7-9; and problems revolving around time management and pacing.
- Full Text:
- Date Issued: 2009
Effect of the killing method on post-mortem change in length of larvae of Thanatophilus micans (Fabricius, 1794) (Coleoptera: Silphidae) stored in 70% ethanol
- Midgley, John M, Villet, Martin H
- Authors: Midgley, John M , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6857 , http://hdl.handle.net/10962/d1011140
- Description: It is recommended that insect larvae collected for forensic purposes should be killed using the same method as was used to create existing models for rate of development. Certain killing methods have been shown to be preferable because they cause less distortion of the specimens, but these are not always practicable in a particular case, and so a method of correcting for effect of killing method is required. Larvae of all instars of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) were measured and then killed by immersion in ethanol, immersion in hot water or freezing. Samples were re-measured immediately after death, then stored in excess 70% ethanol and re-measured after 1 week and again after 4 weeks. The change in length was significantly different from zero in all samples (t = -9.07022, p < 0.001). An analysis of covariance showed that instar, killing method and storage time all had a significant effect on the change in length. The results showed that T. micans larvae have a great potential for change in length during storage but that the change is not predictable, as the magnitude and sign of the change are variable.
- Full Text:
- Date Issued: 2009
- Authors: Midgley, John M , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6857 , http://hdl.handle.net/10962/d1011140
- Description: It is recommended that insect larvae collected for forensic purposes should be killed using the same method as was used to create existing models for rate of development. Certain killing methods have been shown to be preferable because they cause less distortion of the specimens, but these are not always practicable in a particular case, and so a method of correcting for effect of killing method is required. Larvae of all instars of Thanatophilus micans (Fabricius 1794) (Coleoptera: Silphidae) were measured and then killed by immersion in ethanol, immersion in hot water or freezing. Samples were re-measured immediately after death, then stored in excess 70% ethanol and re-measured after 1 week and again after 4 weeks. The change in length was significantly different from zero in all samples (t = -9.07022, p < 0.001). An analysis of covariance showed that instar, killing method and storage time all had a significant effect on the change in length. The results showed that T. micans larvae have a great potential for change in length during storage but that the change is not predictable, as the magnitude and sign of the change are variable.
- Full Text:
- Date Issued: 2009
Compositional varition of the Essential Oils of Artemisia afra Jacq. from three Provinces in South Africa- A Case Study of its safety
- Oyedeji, O A, Afolayan, A J, Hutchings, A
- Authors: Oyedeji, O A , Afolayan, A J , Hutchings, A
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/748 , vital:29679
- Description: In South Africa, Centella asiatica. (L.) Urb is used traditionally for the treatment of various diseases. Analyses of the essential oil of this medicinal plant revealed 11 monoterpenoid hydrocarbons (20.20%), nine oxygenated monoterpenoids (5.46%), 14 sesquiterpenoid hydrocarbons (68.80%), five oxygenated sesquiterpenoids (3.90%), and one sulfide sesquiterpenoid (0.76%). α.-Humulene (21.06%), β.-caryophyllene (19.08%), bicyclogermacrene (11.22%), germacrene B (6.29%), and myrcene (6.55%) were the predominant constitutes. The essential oil extract exhibited a broad spectrum of antibacterial activities against Gram-positive (Bacillus subtilis, Staphylococcus aureus.) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei.) organisms.
- Full Text: false
- Date Issued: 2009
- Authors: Oyedeji, O A , Afolayan, A J , Hutchings, A
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: http://hdl.handle.net/11260/748 , vital:29679
- Description: In South Africa, Centella asiatica. (L.) Urb is used traditionally for the treatment of various diseases. Analyses of the essential oil of this medicinal plant revealed 11 monoterpenoid hydrocarbons (20.20%), nine oxygenated monoterpenoids (5.46%), 14 sesquiterpenoid hydrocarbons (68.80%), five oxygenated sesquiterpenoids (3.90%), and one sulfide sesquiterpenoid (0.76%). α.-Humulene (21.06%), β.-caryophyllene (19.08%), bicyclogermacrene (11.22%), germacrene B (6.29%), and myrcene (6.55%) were the predominant constitutes. The essential oil extract exhibited a broad spectrum of antibacterial activities against Gram-positive (Bacillus subtilis, Staphylococcus aureus.) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Shigella sonnei.) organisms.
- Full Text: false
- Date Issued: 2009
Predicting geographic distribution of seven blowfly species (Diptera: Calliphoridae) in South Africa
- Richards, C S, Williams, K A, Villet, Martin H
- Authors: Richards, C S , Williams, K A , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6854 , http://hdl.handle.net/10962/d1011135
- Description: The predicted geographic distributions of seven forensically important blowfly species are modelled using the computer program Maxent, based on selected climatic variables for South Africa, a country with large climatic and environmental gradients. It is shown that although temperature was hypothesized to most influence the distributions of these ectotherms, moisture, and particularly humidity, was in fact usually paramount. Chrysomya albiceps (Wiedemann) and C. marginalis (Robineau-Desvoidy) had the most widespread geographic and climatic distribution, while the forest-associated C. inclinata(Walker) was the least widespread. Chrysomya putoria (Wiedemann) and C. megacephala (Fabricius) had very similar predicted distributions that were restricted mainly to Limpopo, Mpumalanga, KwaZulu-Natal and the coast of the Eastern Cape. Chrysomya chloropyga (Wiedemann) and Calliphora croceipalpis (Jaennicke) were the only species predicted to occur at high altitudes. Blowfly distributions restricted to part of the map area were predicted better than those that were more widespread in the region, presumably because species with extremely widespread distributions in a study area occupy nearly the whole range of variation of most predictor variables, leaving little variation with which themaximumentropy modelling method can discriminate between presence and absence of the organism.
- Full Text:
- Date Issued: 2009
Predicting geographic distribution of seven blowfly species (Diptera: Calliphoridae) in South Africa
- Authors: Richards, C S , Williams, K A , Villet, Martin H
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6854 , http://hdl.handle.net/10962/d1011135
- Description: The predicted geographic distributions of seven forensically important blowfly species are modelled using the computer program Maxent, based on selected climatic variables for South Africa, a country with large climatic and environmental gradients. It is shown that although temperature was hypothesized to most influence the distributions of these ectotherms, moisture, and particularly humidity, was in fact usually paramount. Chrysomya albiceps (Wiedemann) and C. marginalis (Robineau-Desvoidy) had the most widespread geographic and climatic distribution, while the forest-associated C. inclinata(Walker) was the least widespread. Chrysomya putoria (Wiedemann) and C. megacephala (Fabricius) had very similar predicted distributions that were restricted mainly to Limpopo, Mpumalanga, KwaZulu-Natal and the coast of the Eastern Cape. Chrysomya chloropyga (Wiedemann) and Calliphora croceipalpis (Jaennicke) were the only species predicted to occur at high altitudes. Blowfly distributions restricted to part of the map area were predicted better than those that were more widespread in the region, presumably because species with extremely widespread distributions in a study area occupy nearly the whole range of variation of most predictor variables, leaving little variation with which themaximumentropy modelling method can discriminate between presence and absence of the organism.
- Full Text:
- Date Issued: 2009
Antiretroviral therapy in a South African public health care setting – facilitating and constraining factors
- Ruud, K W, Srinivas, Sunitha C, Toverud, E-L
- Authors: Ruud, K W , Srinivas, Sunitha C , Toverud, E-L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6453 , http://hdl.handle.net/10962/d1006831
- Description: The objective of the study was to identify and document facilitating and constraining factors in the antiretroviral therapy (ART) programme in a public health care setting in the Eastern Cape, South Africa. Observations for the study were carried out in a district hospital and two down-referral clinics in Makana Local Services Area in the Eastern Cape Province. Two discussion groups with key stakeholders were conducted to gather information about opinions and experiences among the health care providers (HCPs). It was found that the operating ART programme in this setting has been integrated in the existing down-referral health care system, based on follow-up in primary health care (PHC) clinics. Treatment is provided free of charge. The treatment programme provides the patients with access to counselling, nutritional assistance, psychosocial support and social welfare evaluation. However, increasing patient numbers and lack of human resources leads to a heavy workload for the HCPs involved with the ART programme. The need for additional, educated health workers is a major constraint for progress in provision of health care to patients who have accepted their HIV status, and are enrolled, or waiting to be enrolled, on the ART. However, delegation of work tasks among available HCPs and good communication between HCPs in the different clinics is a facilitating factor that ensures efficient use of the human resources available. Conclusion: Taking into account the challenges in a resource-constrained setting, this programme shows potential for functioning well as a provider of ART for those who are able and willing to access it. Considering an already heavy workload for HCPs, limitations and challenges still exist in reaching out with adequate treatment to a greater number of people who need ART.
- Full Text:
- Date Issued: 2009
- Authors: Ruud, K W , Srinivas, Sunitha C , Toverud, E-L
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6453 , http://hdl.handle.net/10962/d1006831
- Description: The objective of the study was to identify and document facilitating and constraining factors in the antiretroviral therapy (ART) programme in a public health care setting in the Eastern Cape, South Africa. Observations for the study were carried out in a district hospital and two down-referral clinics in Makana Local Services Area in the Eastern Cape Province. Two discussion groups with key stakeholders were conducted to gather information about opinions and experiences among the health care providers (HCPs). It was found that the operating ART programme in this setting has been integrated in the existing down-referral health care system, based on follow-up in primary health care (PHC) clinics. Treatment is provided free of charge. The treatment programme provides the patients with access to counselling, nutritional assistance, psychosocial support and social welfare evaluation. However, increasing patient numbers and lack of human resources leads to a heavy workload for the HCPs involved with the ART programme. The need for additional, educated health workers is a major constraint for progress in provision of health care to patients who have accepted their HIV status, and are enrolled, or waiting to be enrolled, on the ART. However, delegation of work tasks among available HCPs and good communication between HCPs in the different clinics is a facilitating factor that ensures efficient use of the human resources available. Conclusion: Taking into account the challenges in a resource-constrained setting, this programme shows potential for functioning well as a provider of ART for those who are able and willing to access it. Considering an already heavy workload for HCPs, limitations and challenges still exist in reaching out with adequate treatment to a greater number of people who need ART.
- Full Text:
- Date Issued: 2009
Evaluating the IRI topside model for the South African region: An overview of the modelling techniques
- Sibanda, Patrick, McKinnell, Lee-Anne
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
- Date Issued: 2009
- Authors: Sibanda, Patrick , McKinnell, Lee-Anne
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6810 , http://hdl.handle.net/10962/d1004303
- Description: The representation of the topside ionosphere (the region above the F2 peak) is critical because of the limited experimental data available. Over the years, a wide range of models have been developed in an effort to represent the behaviour and the shape of the electron density (Ne) profile of the topside ionosphere. Various studies have been centred around calculating the vertical scale height (VSH) and have included (a) obtaining VSH from Global Positioning System (GPS) derived total electron content (TEC), (b) calculating the VSH from ground-based ionosonde measurements, (c) using topside sounder vertical Ne profiles to obtain the VSH. One or a combination of the topside profilers (Chapman function, exponential function, sech-squared (Epstein) function, and/or parabolic function) is then used to reconstruct the topside Ne profile. The different approaches and the modelling techniques are discussed with a view to identifying the most adequate approach to apply to the South African region’s topside modelling efforts. The IRI-2001 topside model is evaluated based on how well it reproduces measured topside profiles over the South African region. This study is a first step in the process of developing a South African topside ionosphere model.
- Full Text:
- Date Issued: 2009
Pseudopolydora species associated with mollusc shells on the south coast of South Africa, with the description of Ps. dayii, sp nov
- Authors: Simon, Carol A
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6875 , http://hdl.handle.net/10962/d1011623
- Description: Two species of the genus Pseudopolydora, Ps. dayii, sp. nov. and Ps. antennata, were associated with gastropods on the south and south-east coasts of South Africa. Pseudopolydora dayii is characterized by prominent post-chaetal notopodial lobes on chaetiger 1 with very long chaetae, a prominent occipital tentacle, having hooded hooks that start on chaetiger 9, branchiae that start on chaetiger 6, stout hooks and lobes placed latero-posteriorly to the hooded hooks in posterior chaetigers. It is a surface-fouler and was found on several species of wild gastropods at four of the five sites sampled and from additional material from the south-west coast and on cultured abalone (Haliotis midae) at a farm on the south-west coast. Three individuals of Ps. antennata were found only with oysters at the easternmost site. This was the first record of this species outside of the Western Cape Province and it is possible that their association with the oysters was fortuitous.
- Full Text:
- Date Issued: 2009
- Authors: Simon, Carol A
- Date: 2009
- Language: English
- Type: text , Article
- Identifier: vital:6875 , http://hdl.handle.net/10962/d1011623
- Description: Two species of the genus Pseudopolydora, Ps. dayii, sp. nov. and Ps. antennata, were associated with gastropods on the south and south-east coasts of South Africa. Pseudopolydora dayii is characterized by prominent post-chaetal notopodial lobes on chaetiger 1 with very long chaetae, a prominent occipital tentacle, having hooded hooks that start on chaetiger 9, branchiae that start on chaetiger 6, stout hooks and lobes placed latero-posteriorly to the hooded hooks in posterior chaetigers. It is a surface-fouler and was found on several species of wild gastropods at four of the five sites sampled and from additional material from the south-west coast and on cultured abalone (Haliotis midae) at a farm on the south-west coast. Three individuals of Ps. antennata were found only with oysters at the easternmost site. This was the first record of this species outside of the Western Cape Province and it is possible that their association with the oysters was fortuitous.
- Full Text:
- Date Issued: 2009