A re-evaluation of plastochron index determination in peas - a case for using leaflet length
- Ade-Ademilua, Omobolanle Elizabeth, Botha, Christiaan E J
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6491 , http://hdl.handle.net/10962/d1004472
- Description: The plastochron index (PI) is a measure of plant growth reports our findings on PI using the average length of and can be used to determine growth rate, based upon the first pair of leaflets on each node. Early leaflet appearance of successive leaves on the axis of the growth in peas occurs exponentially and the early plant. PI should under ideal growth conditions be a stages of growth of successive pairs of leaflets occur at regular event and should be predictable with a relatively the same relative growth rate. Given that growth of small error of a few hours. PI has been variously leaflets during early development can be measured calculated in peas, and each method reported has had successfully, we propose the use of leaflet growth as a with it a number of problems that do not allow for measure of the plastochron index in peas. Our results reasonable prediction of PI. Internode length varies suggest that plant age is best expressed using the greatly and is dependent upon the variety, which may be plastochron index, which is a measure of the time short- or long-stemmed; thus this parameter is not ideal interval between the initiations of successive events — for determining growth rate or plant age. This paper in the case of peas, of successive pairs of leaflets.
- Full Text:
- Date Issued: 2005
- Authors: Ade-Ademilua, Omobolanle Elizabeth , Botha, Christiaan E J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6491 , http://hdl.handle.net/10962/d1004472
- Description: The plastochron index (PI) is a measure of plant growth reports our findings on PI using the average length of and can be used to determine growth rate, based upon the first pair of leaflets on each node. Early leaflet appearance of successive leaves on the axis of the growth in peas occurs exponentially and the early plant. PI should under ideal growth conditions be a stages of growth of successive pairs of leaflets occur at regular event and should be predictable with a relatively the same relative growth rate. Given that growth of small error of a few hours. PI has been variously leaflets during early development can be measured calculated in peas, and each method reported has had successfully, we propose the use of leaflet growth as a with it a number of problems that do not allow for measure of the plastochron index in peas. Our results reasonable prediction of PI. Internode length varies suggest that plant age is best expressed using the greatly and is dependent upon the variety, which may be plastochron index, which is a measure of the time short- or long-stemmed; thus this parameter is not ideal interval between the initiations of successive events — for determining growth rate or plant age. This paper in the case of peas, of successive pairs of leaflets.
- Full Text:
- Date Issued: 2005
A newly discovered population of the critically endangered false limpet Siphonaria compressa Allanson, 1958 (Pulmonata: Siphonariidae), with observations on its reproductive biology
- Allanson, Brian R, Herbert, D G
- Authors: Allanson, Brian R , Herbert, D G
- Date: 2005-05-23
- Language: English
- Type: Article
- Identifier: vital:6833 , http://hdl.handle.net/10962/d1007570
- Description: The endangered false limpet, Siphonaria compressa, originally described by Allanson in 1958 from Langebaan Lagoon, Saldanha, has been found living in intertidal eelgrass meadows in the embayment of the Knysna River estuary at Bollard Bay, Leisure Isle, Knysna, South Africa. This represents only the second known site of occurrence of the species. Although classified by the IUCN as critically endangered, the Knysna population is viable. , Acrobat Distiller 6.0 (Windows)
- Full Text:
- Authors: Allanson, Brian R , Herbert, D G
- Date: 2005-05-23
- Language: English
- Type: Article
- Identifier: vital:6833 , http://hdl.handle.net/10962/d1007570
- Description: The endangered false limpet, Siphonaria compressa, originally described by Allanson in 1958 from Langebaan Lagoon, Saldanha, has been found living in intertidal eelgrass meadows in the embayment of the Knysna River estuary at Bollard Bay, Leisure Isle, Knysna, South Africa. This represents only the second known site of occurrence of the species. Although classified by the IUCN as critically endangered, the Knysna population is viable. , Acrobat Distiller 6.0 (Windows)
- Full Text:
Monitoring the oceanic flow between Africa and Antarctica: report of the first Good Hope cruise
- Ansorge, Isabelle J, Speich, S, Lutjeharms, Johan R E, Goni, G J, Rautenbach, C J de W, Froneman, P William, Rouault, M, Garzoli, S
- Authors: Ansorge, Isabelle J , Speich, S , Lutjeharms, Johan R E , Goni, G J , Rautenbach, C J de W , Froneman, P William , Rouault, M , Garzoli, S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6832 , http://hdl.handle.net/10962/d1007568
- Description: The Southern Ocean plays a major role in the global oceanic circulation, as a component of the Meridional Overturning Circulation, and it is postulated that it has a great influence on present-day climate. However, our understanding of its complex three-dimensional dynamics and of the impact of its variability on the climate system is rudimentary. The newly constituted, international GoodHope research venture aims to address this knowledge gap by establishing a programme of regular observations across the Southern Ocean between the African and Antarctic continents. The objectives of this programme are fivefold: (1) to improve understanding of Indo-Atlantic inter-ocean exchanges and their impact on the global thermohaline circulation and thus on global climate change; (2) to understand in more detail the influence these exchanges have on the climate variability of the southern African subcontinent; (3) to monitor the variability of the main Southern Ocean frontal systems associated with the Antarctic Circumpolar Current; (4) to study air-sea exchanges and their role on the global heat budget, with particular emphasis on the intense exchanges occurring within the Agulhas Retroflection region south of South Africa, and (5) to examine the role of major frontal systems as areas of elevated biological activity and as biogeographical barriers to the distribution of plankton. We present here preliminary results on the physical and biological structure of the frontal systems using the first GoodHope transect that was completed during February-March 2004.
- Full Text:
- Date Issued: 2005
- Authors: Ansorge, Isabelle J , Speich, S , Lutjeharms, Johan R E , Goni, G J , Rautenbach, C J de W , Froneman, P William , Rouault, M , Garzoli, S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6832 , http://hdl.handle.net/10962/d1007568
- Description: The Southern Ocean plays a major role in the global oceanic circulation, as a component of the Meridional Overturning Circulation, and it is postulated that it has a great influence on present-day climate. However, our understanding of its complex three-dimensional dynamics and of the impact of its variability on the climate system is rudimentary. The newly constituted, international GoodHope research venture aims to address this knowledge gap by establishing a programme of regular observations across the Southern Ocean between the African and Antarctic continents. The objectives of this programme are fivefold: (1) to improve understanding of Indo-Atlantic inter-ocean exchanges and their impact on the global thermohaline circulation and thus on global climate change; (2) to understand in more detail the influence these exchanges have on the climate variability of the southern African subcontinent; (3) to monitor the variability of the main Southern Ocean frontal systems associated with the Antarctic Circumpolar Current; (4) to study air-sea exchanges and their role on the global heat budget, with particular emphasis on the intense exchanges occurring within the Agulhas Retroflection region south of South Africa, and (5) to examine the role of major frontal systems as areas of elevated biological activity and as biogeographical barriers to the distribution of plankton. We present here preliminary results on the physical and biological structure of the frontal systems using the first GoodHope transect that was completed during February-March 2004.
- Full Text:
- Date Issued: 2005
Regional development in South Africa’s West Coast: 'dividends on the process side'?
- Bek, David, Binns, Tony, Nel, Etienne L
- Authors: Bek, David , Binns, Tony , Nel, Etienne L
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6674 , http://hdl.handle.net/10962/d1006648
- Description: Academics, policy-makers and consultants have been increasingly focusing upon the 'region' as the crucible of economic development. This regionalist approach places institutions at the centre of the process of stimulating growth. Much debate has been ongoing in academic circles, particularly those inhabited by economic geographers, about the veracity of the regionalist approach and the explanatory power of the terminology associated with it. This paper analyses explicit efforts to engender regional economic development in the West Coast of South Africa. Our empirical evaluation indicates that policy actors have sought to upgrade the institutional infrastructure of the region and that some significant achievements are evident within this realm. However, these achievements are yet to be associated with sustained regional economic takeoff. The paper concludes by asking searching questions about the ability of the regionalist approach to deliver meaningful socio-economic transformation.
- Full Text:
- Date Issued: 2005
- Authors: Bek, David , Binns, Tony , Nel, Etienne L
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6674 , http://hdl.handle.net/10962/d1006648
- Description: Academics, policy-makers and consultants have been increasingly focusing upon the 'region' as the crucible of economic development. This regionalist approach places institutions at the centre of the process of stimulating growth. Much debate has been ongoing in academic circles, particularly those inhabited by economic geographers, about the veracity of the regionalist approach and the explanatory power of the terminology associated with it. This paper analyses explicit efforts to engender regional economic development in the West Coast of South Africa. Our empirical evaluation indicates that policy actors have sought to upgrade the institutional infrastructure of the region and that some significant achievements are evident within this realm. However, these achievements are yet to be associated with sustained regional economic takeoff. The paper concludes by asking searching questions about the ability of the regionalist approach to deliver meaningful socio-economic transformation.
- Full Text:
- Date Issued: 2005
The effect of prolonged cold storage of eland (Taurotragus oryx) cauda epididymides on the spermatozoa: possible implications for the conservation of biodiversity
- Bissett, Charlene, Bernard, Ric T F
- Authors: Bissett, Charlene , Bernard, Ric T F
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6947 , http://hdl.handle.net/10962/d1011976
- Description: The objectives of this study were to investigate the effects of prolonged storage of cauda epididymides at 4 °C on spermatozoa, and to determine the practicality of utilising epididymal sperm, harvested from testes collected during routine culling of game animals, in assisted reproductive technologies. Testes from eland (Taurotragus oryx) were collected and epididymides removed and maintained at 4 °C. Sperm motility, viability, morphology and membrane integrity were examined at 12 h intervals for 108 h. Sperm motility and viability were significantly lower at the end of the experiment than at the start (P < 0.05) and there was individual variation in the rate at which motility and viability declined. The total number of normal sperm decreased significantly with prolonged storage at 4 °C. Midpiece defects were the most common and head and tail abnormalities were rare. A significant decrease in acrosomal and nuclear membrane integrity was observed with prolonged cold storage but there was no significant change in cell membrane integrity. However, about 30% of epididymal sperm survived for 3 days at 4 °C and more than 10% survived for 4 days, and it should be possible to use sperm from culled animals in some assisted reproductive technologies.
- Full Text:
- Date Issued: 2005
- Authors: Bissett, Charlene , Bernard, Ric T F
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6947 , http://hdl.handle.net/10962/d1011976
- Description: The objectives of this study were to investigate the effects of prolonged storage of cauda epididymides at 4 °C on spermatozoa, and to determine the practicality of utilising epididymal sperm, harvested from testes collected during routine culling of game animals, in assisted reproductive technologies. Testes from eland (Taurotragus oryx) were collected and epididymides removed and maintained at 4 °C. Sperm motility, viability, morphology and membrane integrity were examined at 12 h intervals for 108 h. Sperm motility and viability were significantly lower at the end of the experiment than at the start (P < 0.05) and there was individual variation in the rate at which motility and viability declined. The total number of normal sperm decreased significantly with prolonged storage at 4 °C. Midpiece defects were the most common and head and tail abnormalities were rare. A significant decrease in acrosomal and nuclear membrane integrity was observed with prolonged cold storage but there was no significant change in cell membrane integrity. However, about 30% of epididymal sperm survived for 3 days at 4 °C and more than 10% survived for 4 days, and it should be possible to use sperm from culled animals in some assisted reproductive technologies.
- Full Text:
- Date Issued: 2005
Diet and daily ration of two nototheniid fish on the shelf of the sub-Antarctic Prince Edward Islands
- Bushula, T, Pakhomov, Evgeny A, Kaehler, Sven, Davis, S, Kalin, R M
- Authors: Bushula, T , Pakhomov, Evgeny A , Kaehler, Sven , Davis, S , Kalin, R M
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6948 , http://hdl.handle.net/10962/d1011977
- Description: The seasonal dietary composition and estimates of daily consumption rate of Lepidonotothen larseni and Gobionotothen marionensis juveniles were obtained for the first time using fish collected near sub-Antarctic Prince Edward Islands during April 1999–2003. The diet of L. larseni consisted mainly of pelagic prey, with copepods and arrow worms making up the most significant prey groups and accounting for 46% and 40% of prey mass, respectively. The diet of G. marionensis was more diverse than that of L. larseni and was composed mainly of benthic prey, including bottom-dwelling decapods (Nauticaris marionis) and sedentary polychaetes, which accounted for 54% and 30% of prey mass, respectively. During the present study, dietary overlap between juveniles of L. larseni and G. marionensis was very low (<5%) indicating that competition for food resources between them was negligible. They not only relied on different prey species, both also exhibited different diel feeding regimes. Daily consumption rate of L. larseni and G. marionensis juveniles was estimated to be 4.5% and 5.2% of body dry mass, respectively. Stomach contents and stable isotope analyses suggested, that both L. larseni and G. marionensis occupy the forth-trophic level of the sub-Antarctic food web but depend mainly on allochthonous and autochthonous (kelp derived) organic matter, respectively.
- Full Text:
- Date Issued: 2005
- Authors: Bushula, T , Pakhomov, Evgeny A , Kaehler, Sven , Davis, S , Kalin, R M
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6948 , http://hdl.handle.net/10962/d1011977
- Description: The seasonal dietary composition and estimates of daily consumption rate of Lepidonotothen larseni and Gobionotothen marionensis juveniles were obtained for the first time using fish collected near sub-Antarctic Prince Edward Islands during April 1999–2003. The diet of L. larseni consisted mainly of pelagic prey, with copepods and arrow worms making up the most significant prey groups and accounting for 46% and 40% of prey mass, respectively. The diet of G. marionensis was more diverse than that of L. larseni and was composed mainly of benthic prey, including bottom-dwelling decapods (Nauticaris marionis) and sedentary polychaetes, which accounted for 54% and 30% of prey mass, respectively. During the present study, dietary overlap between juveniles of L. larseni and G. marionensis was very low (<5%) indicating that competition for food resources between them was negligible. They not only relied on different prey species, both also exhibited different diel feeding regimes. Daily consumption rate of L. larseni and G. marionensis juveniles was estimated to be 4.5% and 5.2% of body dry mass, respectively. Stomach contents and stable isotope analyses suggested, that both L. larseni and G. marionensis occupy the forth-trophic level of the sub-Antarctic food web but depend mainly on allochthonous and autochthonous (kelp derived) organic matter, respectively.
- Full Text:
- Date Issued: 2005
Sperm morphology in four species of African platypleurine cicadas (Hemiptera: Cicadomorpha: Cicadidae)
- Chawanji, A S, Hodgson, Alan N, Villet, Martin H
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
- Authors: Chawanji, A S , Hodgson, Alan N , Villet, Martin H
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6917 , http://hdl.handle.net/10962/d1011880
- Description: Mature spermatozoa from four species of platypleurine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis and P. hirtipennis) were examined by light and electron microscopy. The filiform sperm have a similar ultrastructure in all species but notable variations were found in sperm dimensions. All species produce more than one discrete length of nucleated, motile sperm, a form of polymorphism termed polymegaly. Polymegaly is expressed in two ways: sperm have bi- or trimodal head and tail lengths. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming a spermatodesm. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with an electron-lucent central medulla and a denser cortex. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the centriolar adjunct. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely affiliated.
- Full Text:
- Date Issued: 2005
Comparison of maximal aerobic capacity during running and lifting activities : research article
- Christie, Candice J, Scott, Patricia A
- Authors: Christie, Candice J , Scott, Patricia A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6745 , http://hdl.handle.net/10962/d1009314
- Description: Acknowledging the specificity of assessing maximal output, the purpose of this paper was to compare the physiological and perceptual responses during a traditional running activity and the common industrial task of lifting; both were taken to maximal effort. The responses of eight male participants were measured during both physical activities separated by at least five days: i) a progressive speed protocol (PSP) involved running on a treadmill at increasing speeds, starting at 10 km.h[superscript -1] and increasing by 1 km.h[superscript -1] every minute until exhaustion; ii) a progressive frequency protocol (PFP) required participants to lift a load of 20% body mass at increasing lifting frequencies, starting at one lift every 10s and reducing the time between lifts by 1s every minute until exhaustion. Physiological responses were measured using a portable on-line system, the K4b[superscript 2] (Cosmed(r)). "Central" perceptual measures were obtained every minute using the rating of perceived exertion (RPE) scale. Results: Responses increased progressively with augmented exercise intensity in both protocols; however, oxygen consumption and peak oxygen values were both lower during the lifting protocol compared to the running protocol. In contrast to the oxygen uptake responses, peak RER values were significantly higher during lifting (mean of 1.32) than running (mean of 1.18), while maximal heart rate and perceptual responses revealed no significant difference between the two protocols. These findings caution against using the 'traditional' treadmill protocol to assess the aerobic capacity of manual labourers involved in lifting, as it is evident that the traditional lower body protocol will indicate a higher capacity than the maximum capacity of an upper body activity, which could lead to manual labourers being taxed beyond acceptable limits.
- Full Text:
- Date Issued: 2005
- Authors: Christie, Candice J , Scott, Patricia A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6745 , http://hdl.handle.net/10962/d1009314
- Description: Acknowledging the specificity of assessing maximal output, the purpose of this paper was to compare the physiological and perceptual responses during a traditional running activity and the common industrial task of lifting; both were taken to maximal effort. The responses of eight male participants were measured during both physical activities separated by at least five days: i) a progressive speed protocol (PSP) involved running on a treadmill at increasing speeds, starting at 10 km.h[superscript -1] and increasing by 1 km.h[superscript -1] every minute until exhaustion; ii) a progressive frequency protocol (PFP) required participants to lift a load of 20% body mass at increasing lifting frequencies, starting at one lift every 10s and reducing the time between lifts by 1s every minute until exhaustion. Physiological responses were measured using a portable on-line system, the K4b[superscript 2] (Cosmed(r)). "Central" perceptual measures were obtained every minute using the rating of perceived exertion (RPE) scale. Results: Responses increased progressively with augmented exercise intensity in both protocols; however, oxygen consumption and peak oxygen values were both lower during the lifting protocol compared to the running protocol. In contrast to the oxygen uptake responses, peak RER values were significantly higher during lifting (mean of 1.32) than running (mean of 1.18), while maximal heart rate and perceptual responses revealed no significant difference between the two protocols. These findings caution against using the 'traditional' treadmill protocol to assess the aerobic capacity of manual labourers involved in lifting, as it is evident that the traditional lower body protocol will indicate a higher capacity than the maximum capacity of an upper body activity, which could lead to manual labourers being taxed beyond acceptable limits.
- Full Text:
- Date Issued: 2005
Attitudes of Xhosa-speaking students at the University of Fort Hare towards the use of Xhosa as a language of learning and teaching (LOLT)
- Dalvit, Lorenzo, De Klerk, Vivian A
- Authors: Dalvit, Lorenzo , De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6100 , http://hdl.handle.net/10962/d1008664
- Description: This article presents and discusses the results of a survey of a sample of Xhosa-speaking students at the University of Fort Hare regarding their attitudes towards the possible introduction of Xhosa as a medium of instruction at this institution. The research takes into account, among other things, the students' attitudes towards English and Xhosa and their opinions and beliefs about the introduction of dual-mediumship and its possible consequences. The survey was conducted with questionnaires and interviews and the results were first analysed as a whole, and then split into different categories according to gender, year of study, subject studied etc. This analysis indicates that while English is recognised as the dominant language in South Africa and, more specifically, in the domain of education, some categories of respondents acknowledge the usefulness of Xhosa as an additional medium of instruction. This survey clearly shows that it would make little sense to present Xhosa-speaking students at Fort Hare with a rigid choice between the existing English-medium and a dual-medium (English and Xhosa) policy and that more nuanced options would need to be offered. For example, respondents seem to consider the use of Xhosa as a medium of instruction more appropriate in the first years of study, for selected subjects and in some domains within the academic context rather than others. This study can be fruitfully compared with similar research carried out at other South African institutions. Moreover, the results of the present research can be used to inform future decisions regarding language policy at the University of Fort Hare.
- Full Text:
- Date Issued: 2005
- Authors: Dalvit, Lorenzo , De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6100 , http://hdl.handle.net/10962/d1008664
- Description: This article presents and discusses the results of a survey of a sample of Xhosa-speaking students at the University of Fort Hare regarding their attitudes towards the possible introduction of Xhosa as a medium of instruction at this institution. The research takes into account, among other things, the students' attitudes towards English and Xhosa and their opinions and beliefs about the introduction of dual-mediumship and its possible consequences. The survey was conducted with questionnaires and interviews and the results were first analysed as a whole, and then split into different categories according to gender, year of study, subject studied etc. This analysis indicates that while English is recognised as the dominant language in South Africa and, more specifically, in the domain of education, some categories of respondents acknowledge the usefulness of Xhosa as an additional medium of instruction. This survey clearly shows that it would make little sense to present Xhosa-speaking students at Fort Hare with a rigid choice between the existing English-medium and a dual-medium (English and Xhosa) policy and that more nuanced options would need to be offered. For example, respondents seem to consider the use of Xhosa as a medium of instruction more appropriate in the first years of study, for selected subjects and in some domains within the academic context rather than others. This study can be fruitfully compared with similar research carried out at other South African institutions. Moreover, the results of the present research can be used to inform future decisions regarding language policy at the University of Fort Hare.
- Full Text:
- Date Issued: 2005
Anti-oesophageal cancer activity in extracts of deep-water Marion Island sponges
- Davies-Coleman, Michael T, Froneman, P William, Keyzers, Robert A, Whibley, Catherine, Hendricks, Denver T, Samaai, Toufiek, McQuaid, Christopher D
- Authors: Davies-Coleman, Michael T , Froneman, P William , Keyzers, Robert A , Whibley, Catherine , Hendricks, Denver T , Samaai, Toufiek , McQuaid, Christopher D
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6569 , http://hdl.handle.net/10962/d1004132
- Description: Oesophageal cancer is one of the most common causes of cancer-related deaths in South African black males. The limited efficacy of chemotherapeutic agents to treat this disease has prompted a search for potential new chemical entities with anticancer properties. We report here on the evidence for anti-oesophageal cancer activity in the methanolic extracts of five species of sponges dredged from a depth of approximately 100 m in the vicinity of Marion Island in the Southern Ocean during the autumn of 2004.
- Full Text:
- Date Issued: 2005
- Authors: Davies-Coleman, Michael T , Froneman, P William , Keyzers, Robert A , Whibley, Catherine , Hendricks, Denver T , Samaai, Toufiek , McQuaid, Christopher D
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6569 , http://hdl.handle.net/10962/d1004132
- Description: Oesophageal cancer is one of the most common causes of cancer-related deaths in South African black males. The limited efficacy of chemotherapeutic agents to treat this disease has prompted a search for potential new chemical entities with anticancer properties. We report here on the evidence for anti-oesophageal cancer activity in the methanolic extracts of five species of sponges dredged from a depth of approximately 100 m in the vicinity of Marion Island in the Southern Ocean during the autumn of 2004.
- Full Text:
- Date Issued: 2005
Procedural meanings of well in a corpus of Xhosa English
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6128 , http://hdl.handle.net/10962/d1011579
- Description: This article explores the use of the pragmatic marker well in a large corpus of the discourse of non-mother tongue speakers of Xhosa English, which is a sub-variety of Black South African English. A brief overview of discourse markers in general and of well in particular is provided, and the problems they pose to linguists in terms of difficulties in defining their syntactic, semantic and pragmatic properties are examined. After a brief description of the nature of the corpus of Xhosa English on which the study is based, and of the methodological approach which was followed, the rest of the article focuses on a fairly detailed exposition of the overall trends in contextualised uses and procedural meanings of well in the corpus, along with examples. Some (limited) parallels are drawn between the use of well in XE and other English corpora, in order to highlight the problems experienced by L2 learners in acquiring discourse markers.
- Full Text:
- Date Issued: 2005
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6128 , http://hdl.handle.net/10962/d1011579
- Description: This article explores the use of the pragmatic marker well in a large corpus of the discourse of non-mother tongue speakers of Xhosa English, which is a sub-variety of Black South African English. A brief overview of discourse markers in general and of well in particular is provided, and the problems they pose to linguists in terms of difficulties in defining their syntactic, semantic and pragmatic properties are examined. After a brief description of the nature of the corpus of Xhosa English on which the study is based, and of the methodological approach which was followed, the rest of the article focuses on a fairly detailed exposition of the overall trends in contextualised uses and procedural meanings of well in the corpus, along with examples. Some (limited) parallels are drawn between the use of well in XE and other English corpora, in order to highlight the problems experienced by L2 learners in acquiring discourse markers.
- Full Text:
- Date Issued: 2005
The use of actually in spoken Xhosa English : a corpus study
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6136 , http://hdl.handle.net/10962/d1011588
- Description: The aim of this paper is to provide an overview of the semantic and syntactic characteristics of the discourse marker actually, and then to describe and explain how it is used by mothertongue (MT) Xhosa speakers who have learned English as an additional language. Such a description may provide a useful benchmark for comparison with MT norms. The source of data for the study is a corpus of approximately half a million words of transcribed spontaneous dialogue between Xhosa English speakers.
- Full Text:
- Date Issued: 2005
- Authors: De Klerk, Vivian A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6136 , http://hdl.handle.net/10962/d1011588
- Description: The aim of this paper is to provide an overview of the semantic and syntactic characteristics of the discourse marker actually, and then to describe and explain how it is used by mothertongue (MT) Xhosa speakers who have learned English as an additional language. Such a description may provide a useful benchmark for comparison with MT norms. The source of data for the study is a corpus of approximately half a million words of transcribed spontaneous dialogue between Xhosa English speakers.
- Full Text:
- Date Issued: 2005
Phylogenetic congruence of mealybugs and their primary endosymbionts
- Downie, Douglas A, Gullan, P J
- Authors: Downie, Douglas A , Gullan, P J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6905 , http://hdl.handle.net/10962/d1011858 , http://dx.doi.org/10.1111/j.1420-9101.2004.00834.x
- Description: Tight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
- Full Text:
- Date Issued: 2005
- Authors: Downie, Douglas A , Gullan, P J
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6905 , http://hdl.handle.net/10962/d1011858 , http://dx.doi.org/10.1111/j.1420-9101.2004.00834.x
- Description: Tight interactions between unrelated organisms such as is seen in plant–insect, host–parasite, or host–symbiont associations may lead to speciation of the smaller partners when their hosts speciate. Totally congruent phylogenies of interacting taxa have not been observed often but a number of studies have provided evidence that various hemipteran insect taxa and their primary bacterial endosymbionts share phylogenetic histories. Like other hemipterans, mealybugs (Pseudococcidae) harbour multiple intracellular bacterial symbionts, which are thought to be strictly vertically inherited, implying codivergence of hosts and symbionts. Here, robust estimates of phylogeny were generated from four fragments of three nuclear genes for mealybugs of the subfamily Pseudococcinae, and a substantial fragment of the 16S–23S rDNA of their P-endosymbionts. Phylogenetic congruence was highly significant, with 75% of nodes on the two trees identical, and significant correlation of branch lengths indicated coincident timing of cladogenesis. It is suggested that the low level of observed incongruence was influenced by uncertainty in phylogenetic estimation, but evolutionary outcomes other than congruence, including host shifts, could not be rejected.
- Full Text:
- Date Issued: 2005
Medicine labels incorporating pictograms: do they influence understanding and adherence?
- Dowse, Roslind, Ehlers, Martina S
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6359 , http://hdl.handle.net/10962/d1006051
- Description: The objective was to determine the influence of medicine labels incorporating pictograms on the understanding of instructions and on adherence. Eighty-seven Xhosa participants attending an outpatient clinic who had been prescribed a short course of antibiotics were randomly allocated to either a control group (41 participants given text-only labels), or an experimental group (46 participants given text + pictogram labels). All participants had a maximum of 10 years of formal schooling. Follow-up home visits were conducted after 3–5 days to assess understanding of instructions and to evaluate adherence. A high adherence of greater than 90% was found for 54% of the experimental group, compared with only 2% of the control group. Average percentages for understanding in the control and experimental groups were 70 and 95%, respectively, and average adherence was 72 and 90%, respectively. The presence of pictograms was found to contribute positively to both understanding of instructions and adherence.
- Full Text:
- Date Issued: 2005
- Authors: Dowse, Roslind , Ehlers, Martina S
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6359 , http://hdl.handle.net/10962/d1006051
- Description: The objective was to determine the influence of medicine labels incorporating pictograms on the understanding of instructions and on adherence. Eighty-seven Xhosa participants attending an outpatient clinic who had been prescribed a short course of antibiotics were randomly allocated to either a control group (41 participants given text-only labels), or an experimental group (46 participants given text + pictogram labels). All participants had a maximum of 10 years of formal schooling. Follow-up home visits were conducted after 3–5 days to assess understanding of instructions and to evaluate adherence. A high adherence of greater than 90% was found for 54% of the experimental group, compared with only 2% of the control group. Average percentages for understanding in the control and experimental groups were 70 and 95%, respectively, and average adherence was 72 and 90%, respectively. The presence of pictograms was found to contribute positively to both understanding of instructions and adherence.
- Full Text:
- Date Issued: 2005
Critical perspectives on research on post-traumatic stress disorder and implications for the South African context
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6228 , http://hdl.handle.net/10962/d1007778
- Description: This article introduces a special issue of the Journal of Psychology in Africa on post-traumatic stress disorder (PTSD) in Africa and particularly in South Africa and examines the critical debate that has surrounded PTSD research. It begins with an examination of the meaning of the term trauma, and of its specialised use within the clinical context and with respect to the concept of PTSD. The diagnostic approach to the detection of PTSD is presented, criteria in the DSM-IV-TR and the ICD-10 are summarised and differences between the two manuals are discussed. Arguments presented by critics of the concept of PTSD are presented and discussed. These concern the historical evolution of the concept, concerns about the universality of PTSD cross-culturally, and problems arising from understanding human suffering from a narrow medical perspective. It is concluded that while there are dangers in thinking of the sequelae of trauma as a medical/psychiatric problem, and while the alarming rate of traumatic events needs to be addressed at the political, economic and societal level, there is an important place for the provision of assessment and treatment of PTSD within a psychiatric/psychological clinical setting.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6228 , http://hdl.handle.net/10962/d1007778
- Description: This article introduces a special issue of the Journal of Psychology in Africa on post-traumatic stress disorder (PTSD) in Africa and particularly in South Africa and examines the critical debate that has surrounded PTSD research. It begins with an examination of the meaning of the term trauma, and of its specialised use within the clinical context and with respect to the concept of PTSD. The diagnostic approach to the detection of PTSD is presented, criteria in the DSM-IV-TR and the ICD-10 are summarised and differences between the two manuals are discussed. Arguments presented by critics of the concept of PTSD are presented and discussed. These concern the historical evolution of the concept, concerns about the universality of PTSD cross-culturally, and problems arising from understanding human suffering from a narrow medical perspective. It is concluded that while there are dangers in thinking of the sequelae of trauma as a medical/psychiatric problem, and while the alarming rate of traumatic events needs to be addressed at the political, economic and societal level, there is an important place for the provision of assessment and treatment of PTSD within a psychiatric/psychological clinical setting.
- Full Text:
- Date Issued: 2005
Trauma, resilience and vulnerability to PTSD : a review and clinical case analysis
- Edwards, David J A, Sakasa, P, Van Wyk, G
- Authors: Edwards, David J A , Sakasa, P , Van Wyk, G
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6230 , http://hdl.handle.net/10962/d1007780
- Description: This article begins with two case examples of a girl and an adolescent who were raped and developed chronic PTSD. These are used as a basis for understanding the role of a range of factors that are associated with resilience and vulnerability in the face of traumatic events. A literature review examines the proportion of individuals who develop PTSD following trauma and the factors associated with vulnerability and resilience. These include gender, developmental factors, social support and personality factors. Psychological factors associated with maintenance of chronic PTSD are also briefly reviewed. This material is used as a basis for reconsidering the case examples. Each case is formulated within a framework based on sources of vulnerability and qualities of resilience. Approaches to intervention are suggested that could address the range of factors making the individuals vulnerable to chronic psychological problems and support resiliency and recovery.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A , Sakasa, P , Van Wyk, G
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6230 , http://hdl.handle.net/10962/d1007780
- Description: This article begins with two case examples of a girl and an adolescent who were raped and developed chronic PTSD. These are used as a basis for understanding the role of a range of factors that are associated with resilience and vulnerability in the face of traumatic events. A literature review examines the proportion of individuals who develop PTSD following trauma and the factors associated with vulnerability and resilience. These include gender, developmental factors, social support and personality factors. Psychological factors associated with maintenance of chronic PTSD are also briefly reviewed. This material is used as a basis for reconsidering the case examples. Each case is formulated within a framework based on sources of vulnerability and qualities of resilience. Approaches to intervention are suggested that could address the range of factors making the individuals vulnerable to chronic psychological problems and support resiliency and recovery.
- Full Text:
- Date Issued: 2005
Treating PTSD in South African contexts : a theoretical framework and a model for developing evidence-based practice
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6231 , http://hdl.handle.net/10962/d1007781
- Description: Several psychological factors contribute to the development and maintenance of post-traumatic stress disorder (PTSD) because they interfere with the emotional processing of the traumatic event. These include problematic and painful emotions such as anxiety, shame, guilt and grief, distorted or dysfunctional cognitions, and cognitive, emotional, and behavioural avoidance mechanisms. Analysis of these maintaining factors provides the basis for current approaches to treatment which support traumatised individuals in facing emotional pain, working to resolve shame, grief and guilt, and expanding existing schemas to accommodate the traumatic event(s). Randomised controlled trials (RCTs) are reviewed in which the efficacy of some of these treatments have been evaluated. While many South African practitioners are familiar with current evidence-based approaches and are skilled at adapting them to local cultural and contextual conditions, a great deal still needs to be done to build a sound research base for local practice in the treatment of PTSD and disseminating that research to practitioners in the field. It is recommended that a case-based evaluation strategy be used to complement the findings of international RCT studies in order to build a foundation of locally contextualised and applicable scientific knowledge.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6231 , http://hdl.handle.net/10962/d1007781
- Description: Several psychological factors contribute to the development and maintenance of post-traumatic stress disorder (PTSD) because they interfere with the emotional processing of the traumatic event. These include problematic and painful emotions such as anxiety, shame, guilt and grief, distorted or dysfunctional cognitions, and cognitive, emotional, and behavioural avoidance mechanisms. Analysis of these maintaining factors provides the basis for current approaches to treatment which support traumatised individuals in facing emotional pain, working to resolve shame, grief and guilt, and expanding existing schemas to accommodate the traumatic event(s). Randomised controlled trials (RCTs) are reviewed in which the efficacy of some of these treatments have been evaluated. While many South African practitioners are familiar with current evidence-based approaches and are skilled at adapting them to local cultural and contextual conditions, a great deal still needs to be done to build a sound research base for local practice in the treatment of PTSD and disseminating that research to practitioners in the field. It is recommended that a case-based evaluation strategy be used to complement the findings of international RCT studies in order to build a foundation of locally contextualised and applicable scientific knowledge.
- Full Text:
- Date Issued: 2005
Unconscious influences on discourses about consciousness : ideology, state-specific science and unformulated experience
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6226 , http://hdl.handle.net/10962/d1007776
- Description: Discussions about consciousness are complicated by the fact that participants do not share a common underlying “ordinary” consciousness. Everyday experience is founded on what Teasdale calls implicational cognition, much of which is not verbally formulated. An unacknowledged aspect of debate is individuals’ attempts to negotiate the expression of their unformulated experience. This is further complicated by the way in which a discourse, based on particular ontological assumptions, exercises an ideological control which limits what underlying aspects of experience can be formulated at all. Tart’s concept of state specific sciences provides a framework within which the role of unformulated experience can be acknowledged and taken into account. Unless this is done, debates will be vitiated by participants engaging in ideological struggles and talking at cross-purposes.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6226 , http://hdl.handle.net/10962/d1007776
- Description: Discussions about consciousness are complicated by the fact that participants do not share a common underlying “ordinary” consciousness. Everyday experience is founded on what Teasdale calls implicational cognition, much of which is not verbally formulated. An unacknowledged aspect of debate is individuals’ attempts to negotiate the expression of their unformulated experience. This is further complicated by the way in which a discourse, based on particular ontological assumptions, exercises an ideological control which limits what underlying aspects of experience can be formulated at all. Tart’s concept of state specific sciences provides a framework within which the role of unformulated experience can be acknowledged and taken into account. Unless this is done, debates will be vitiated by participants engaging in ideological struggles and talking at cross-purposes.
- Full Text:
- Date Issued: 2005
Post-traumatic stress disorder as a public health concern in South Africa
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6229 , http://hdl.handle.net/10962/d1007779
- Description: This article briefly surveys the extent to which traumatic events are a feature of life all over Africa and provides a comprehensive review of research that documents the pervasiveness of traumatic events in South Africa and the prevalence of PTSD symptoms. The material reviewed includes statistics on crime, violence and accidents, research from clinical settings, and surveys. Several provide evidence for the causal link between traumatic events and the development of PTSD. These studies show that PTSD has been and continues to be a significant problem for public health in South Africa, affecting individuals in all sectors of society and as much a concern with respect to children as to adults.
- Full Text:
- Date Issued: 2005
- Authors: Edwards, David J A
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6229 , http://hdl.handle.net/10962/d1007779
- Description: This article briefly surveys the extent to which traumatic events are a feature of life all over Africa and provides a comprehensive review of research that documents the pervasiveness of traumatic events in South Africa and the prevalence of PTSD symptoms. The material reviewed includes statistics on crime, violence and accidents, research from clinical settings, and surveys. Several provide evidence for the causal link between traumatic events and the development of PTSD. These studies show that PTSD has been and continues to be a significant problem for public health in South Africa, affecting individuals in all sectors of society and as much a concern with respect to children as to adults.
- Full Text:
- Date Issued: 2005
Contrasting spatial heterogeneity of sessile organisms within mussel (Perna perna L.) beds in relation to topographic variability
- Erlandsson, J, McQuaid, Christopher D, Kostylev, V E
- Authors: Erlandsson, J , McQuaid, Christopher D , Kostylev, V E
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6949 , http://hdl.handle.net/10962/d1011979
- Description: We examined the spatial heterogeneity in three sessile rocky shore organisms, the mussel Perna perna, the barnacle Octomeris angulosa (Sowerby) and the red alga Gelidium pristoides (Turn.) at a range of continuous local scales along horizontal transects within mid- and upper mussel beds of South African shores. We also examined the relationships between variability of organisms and topographic features (rock depressions, slope, aspect), and between mussel, barnacle and algal variability over the same scales. To estimate spatial heterogeneity, we analyzed scaling properties of semivariograms using a fractal approach. Relationships between different variables at the different scales were examined by cross-semivariograms. Spatial dependence of P. perna variability increased with spatial dependence of topographic variability, so that scaling regions of mussel and topographic distributions corresponded well. This relationship often improved with larger local scales (mussel cover increased with depressions, steeper slope and aspect towards waves), while at smaller spatial scales, variability in mussel cover was less well explained by variability in topography. The variability of the barnacle O. angulosa exhibited spatial dependence, even on topographically unstructured shores. In contrast, the distribution of the alga G. pristoides revealed high fractal dimensions, showing spatial independence on topographically unstructured shores. Algae also showed a very strong negative relationship with mussels at most local scales, and a negative relationship with barnacles in upper zones, especially at larger local scales. Barnacles may show clear spatial dependence because of hydrodynamics (at larger local scales) and the need to find a future mate in close proximity (at smaller local scales), while algae may show a strong negative relationship with mussels because of competition for space.
- Full Text:
- Date Issued: 2005
- Authors: Erlandsson, J , McQuaid, Christopher D , Kostylev, V E
- Date: 2005
- Language: English
- Type: Article
- Identifier: vital:6949 , http://hdl.handle.net/10962/d1011979
- Description: We examined the spatial heterogeneity in three sessile rocky shore organisms, the mussel Perna perna, the barnacle Octomeris angulosa (Sowerby) and the red alga Gelidium pristoides (Turn.) at a range of continuous local scales along horizontal transects within mid- and upper mussel beds of South African shores. We also examined the relationships between variability of organisms and topographic features (rock depressions, slope, aspect), and between mussel, barnacle and algal variability over the same scales. To estimate spatial heterogeneity, we analyzed scaling properties of semivariograms using a fractal approach. Relationships between different variables at the different scales were examined by cross-semivariograms. Spatial dependence of P. perna variability increased with spatial dependence of topographic variability, so that scaling regions of mussel and topographic distributions corresponded well. This relationship often improved with larger local scales (mussel cover increased with depressions, steeper slope and aspect towards waves), while at smaller spatial scales, variability in mussel cover was less well explained by variability in topography. The variability of the barnacle O. angulosa exhibited spatial dependence, even on topographically unstructured shores. In contrast, the distribution of the alga G. pristoides revealed high fractal dimensions, showing spatial independence on topographically unstructured shores. Algae also showed a very strong negative relationship with mussels at most local scales, and a negative relationship with barnacles in upper zones, especially at larger local scales. Barnacles may show clear spatial dependence because of hydrodynamics (at larger local scales) and the need to find a future mate in close proximity (at smaller local scales), while algae may show a strong negative relationship with mussels because of competition for space.
- Full Text:
- Date Issued: 2005