Effects of small-scale water movement on the settlement and growth rates of the brown mussel Perna perna, on the south-east coast of South Africa
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
Effects of sustained Russian wheat aphid (Diuraphis noxia Mordvilko) feeding on leaf blades of wheat (Triticum aestivum L. cv Adamtas)
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
- Authors: Matsiliza, Babalwa
- Date: 2003
- Subjects: Russian wheat aphid Wheat -- Diseases and pests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4213 , http://hdl.handle.net/10962/d1003782
- Description: Penetration of sink as well as source leaves of wheat plants by the Russian wheat aphid, Diuraphis noxia (Mordvilko) was investigated using light, fluorescence and transmission electron techniques, to determine the feeding strategies adopted by the aphid in penetrating and successfully feeding from the phloem, and to assess the structural effects of the probing and feeding behaviour of D. noxia on the feeding sites. Examination of aphid-infested sink, as well as source leaf tissue, showed that D.noxia probed in cells of the vascular bundle more frequently than mesophyll cells. Within the vascular bundle, thin-walled sieve tubes were visited (probed) more than the other cells. In sink leaf material, 68 of 82 (83%) stylets and stylet tracks encountered during the examination of 1000 serial sections (from 5 different plants) terminated in thin-walled sieve tubes and only 14 (17%) in thick-walled sieve tubes. Thin-walled sieve tubes were visited more significantly than thick-walled sieve tubes. However, examination of the aphid.,.infested sink leaf on a per centimetre basis, from the tip of the leaf, revealed that thick-walled sieve tubes in the area closest to the tip (0-2cm from the tip) were as attractive to the aphid as were thin-walled sieve tubes, with no significant difference in the number of times thick- and thin-walled sieve tubes were probed in this area. Some 2-4cm from the tip however, thinwalled sieve tubes were significantly more probed and therefore more attractive than thick-walled sieve tubes. Examination of 2000 serial sections using aphid-infested source leaf tissue, showed that the thin-walled sieve tubes were significantly more probed than thickwalled sieve tubes, along the whole leaf, expressed as a total of all leaves, as well as on a per centimetre basis along the length of the leaf, with 212 (95%) of 222 terminations within the thin-walled sieve tubes and only 10 (5%) in thick-walledsieve tubes. The aphid probed the small vascular bundles (loading bundles) many more times than intermediate or large transport vascular bundles, in sink as well as source leaf. Of a total of 82 stylets and stylet tracks encountered in sink leaf tissue, 31 terminated in small vascular bundles ang the remaining 28 and 16 were located within large and intermediate vascular bundles respectively. In source leaf tissue 121 of 222 stylets and stylet tracks encountered were associated with small vascular bundles and only 58 tracks and 43 tracks with intermediate and large vascular bundles, respectively. The effect of sustained RWA feeding on the transport capacity was examined after the application of 5,6 carboxyfluoresceine diacetate (5,6-CFDA) in control (sink and source leaf tissue) and aphid-infested (source) wheat leaves, using fluorescence microscopy. After 3h acropetal longitudinal transport of 5,6-CF had occurred in sink leaves in longitudinal veins, as well as a lateral transfer via cross veins and subsequent unloading into mesophyll cells close to the tip of the leaf was observed. In control leaf tissue, the fluorescence front was detected up to about 5cm from the point of application and was only associated with the phloem and not unloaded. In contrast, aphid-infested leaf tissue showed very little 5,6-CF transport, being limited to 2cm or less from the point of application. Structural damage to the phloem in general and to the sieve tubes in particular within of control and infested wheat leaves was investigated using transmission electron microscopy (TEM). In addition, leaf strips were mounted in aniline blue to visualise callose deposition using the fluorescence microscopy. At the TEM level. infested leaf tissue showed various abnormalities, which included destruction of cell contents, membrane damage and subsequent loss of cell contents. TEM studies suggest severe osmotic shock resulted from the aphid's probing. Examination of leaf tissue using fluorescence microscopy showed that there was very little characteristic aniline blue-stained callose visible in control leaf tissue, other than the thin diffuse patches along the sieve plates and punctate spots associated with pore plasmodesmatal areas and plasmodesmatal aggregates. In contrast, the aphid-infested leaf tissue was heavily callosed, with callose deposited not only within the phloem tissue but also in neighbouring vascular parE:}nchyma cells as well. The data collectively suggest that D. noxia feeds preferentially within thin-walled sieve tubes, within the small longitudinal vascular bundles in sink , as well source leaf tissue. Based upon the data presented here the thin-walled sieve tubes in the wheat leaf appear to be more attractive to the aphid and that they are probably more functional in terms of transport system and unlo?lding in sink leaves. Aniline blue stained leaf material that had previously hosted large aphid colonies showed evidence of extensive callose deposits 24 to 36h after the aphids were removed, suggesting that the aphids caused severe mechanical damage to the vascular tissue and mesohyll cells as well. Damage (transient or more permanent) and the subsequent deposition of wound callose, disrupted phloem transport and hence the export of photoassimilate from the leaves.
- Full Text:
- Date Issued: 2003
Electrochemical behavior and detection of dopamine and ascorbic acid at an iron (II) tetrasulfophthalocyanine modified carbon paste microelectrode
- Oni, Joshua, Westbroek, Philippe, Nyokong, Tebello
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
- Date Issued: 2003
- Authors: Oni, Joshua , Westbroek, Philippe , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290279 , vital:56735 , xlink:href="https://doi.org/10.1002/elan.200390104"
- Description: In this article the electrocatalytic behavior of an iron(II)tetrasulfophthalocyanine modified carbon paste microelectrode for the oxidation of dopamine (DA) and ascorbic acid (AA) is described. Although the oxidation potential of ascorbic acid is shifted by over 100 mV to more positive potentials, no peak separation could be obtained. This can be explained by the immediate homogeneous reduction of the oxidation product of dopamine by ascorbic acid in solution. However, this reaction induces a shift of the half-wave potential as a function of ratio of concentration of dopamine to ascorbic acid (cDA/cAA). Therefore it was possible to determine the cAA and cDA from this potential shift and the experimental peak current. Detection limits of 4.5±0.2×10−7 and 7.5±0.5×10−7 mol L−1 were obtained respectively for dopamine and ascorbic acid for cDA/cAA>0.01.
- Full Text:
- Date Issued: 2003
Electrochemical behaviour of thiol-derivatised zinc (II) phthalocyanine complexes and their self-immobilised films at gold electrodes
- Ozoemena, Kenneth I, Nyokong, Tebello
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
- Full Text:
- Date Issued: 2003
- Authors: Ozoemena, Kenneth I , Nyokong, Tebello
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/290295 , vital:56737 , xlink:href="https://doi.org/10.1016/j.microc.2003.08.002"
- Description: Electrochemical properties of novel, peripherally substituted zinc phthalocyanine complex, octa(4-methylphenylthio-) phthalocyaninatozinc(II) [ZnPc(SC6H4CH3)8] (1a) in DMF solution are presented. This complex showed five quasi-reversible/reversible, diffusion-controlled redox couples. Solution voltammetry of 1a showed little contrast with that of its alkythiol-derivative, octabutylthiophthalocyaninatozinc(II) [ZnPc(SC4H9)8] (1b) in that both thiol-substituents tend to show electron-withdrawing influence on the phthalocyanine ligands; complex 1a showing easier reduction and more difficult to oxidation when compared to 1b and other alkyl derivatives. The voltammetric features of the solid ultrathin films of 1a and 1b, immobilized on gold electrodes via the self-assembling technique, are also presented. Interestingly, the self-assembled films are stable and reproducible and provide good suppression to the following Faradaic processes; gold surface oxidation, solution ion species and underpotential deposition (UPD) of copper.
- Full Text:
- Date Issued: 2003
Email security policy implementation in multinational organisations with special reference to privacy laws
- Authors: Dixon, Henry George
- Date: 2003
- Subjects: Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10790 , http://hdl.handle.net/10948/229 , Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Description: In 1971, scientist Ray Tomlinson sent what is now considered the first email message. It was considered as “nothing short of revolutionary … deserv[ing] a spot in the list of great communication inventions such as the printing press, telegraph and telephone” (Festa, 2001). Whereas email was first used exclusively in the military (Arpanet) and in academic circles, it has now become almost ubiquitous, used widely for private, as well as for business correspondence. According to a Berkeley study (Berkeley, 2000), there were approximately 440 million corporate and personal [e-] mailboxes worldwide in 2001, of which more than a third was corporate mailboxes. As a result of the extensive use of email in the corporate environment, Information Officers have to ensure that the use of email adds business value. In an “always on” market place, the efficiency, immediacy and cost effectiveness of email communication are immediately evident. A study by Ferris Research, quoted by Nchor (2001), shows that there is “an overall productivity gain of US$9000 per employee as they send and receive emails to get projects done.” However, the use of email in the corporate envi-ronment also poses business risks that need to be uniquely addressed. Among these “key business risks” (Surfcontrol, 2001) are security risks, viruses, legal liability, pro-ductivity loss and bandwidth abuse. To address the risks mentioned above and to protect the business value of email, spe-cific policies have to be implemented that address email usage. Information Security Policies are defined in most corporate environments. In a study done by Elron Soft-ware (2001), 83% of respondents who have abused email have company policies regu-lating email usage. There appears to be a gap between policy conception and policy implementation. Various factors inhibit effective policy implementation – ethical, legal and cultural. The implementation of corporate policy becomes especially complex in multinational environments where differing information law Email usage is ubiquitous in the modern business environment, but few companies adequately manage the risks associated with email.
- Full Text:
- Date Issued: 2003
- Authors: Dixon, Henry George
- Date: 2003
- Subjects: Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Language: English
- Type: Thesis , Masters , MTech (Business Information Systems)
- Identifier: vital:10790 , http://hdl.handle.net/10948/229 , Electronic mail systems -- Security measures , Privacy, Right of , Electronic mail systems -- Management , Electronic mail systems -- Law and legislation
- Description: In 1971, scientist Ray Tomlinson sent what is now considered the first email message. It was considered as “nothing short of revolutionary … deserv[ing] a spot in the list of great communication inventions such as the printing press, telegraph and telephone” (Festa, 2001). Whereas email was first used exclusively in the military (Arpanet) and in academic circles, it has now become almost ubiquitous, used widely for private, as well as for business correspondence. According to a Berkeley study (Berkeley, 2000), there were approximately 440 million corporate and personal [e-] mailboxes worldwide in 2001, of which more than a third was corporate mailboxes. As a result of the extensive use of email in the corporate environment, Information Officers have to ensure that the use of email adds business value. In an “always on” market place, the efficiency, immediacy and cost effectiveness of email communication are immediately evident. A study by Ferris Research, quoted by Nchor (2001), shows that there is “an overall productivity gain of US$9000 per employee as they send and receive emails to get projects done.” However, the use of email in the corporate envi-ronment also poses business risks that need to be uniquely addressed. Among these “key business risks” (Surfcontrol, 2001) are security risks, viruses, legal liability, pro-ductivity loss and bandwidth abuse. To address the risks mentioned above and to protect the business value of email, spe-cific policies have to be implemented that address email usage. Information Security Policies are defined in most corporate environments. In a study done by Elron Soft-ware (2001), 83% of respondents who have abused email have company policies regu-lating email usage. There appears to be a gap between policy conception and policy implementation. Various factors inhibit effective policy implementation – ethical, legal and cultural. The implementation of corporate policy becomes especially complex in multinational environments where differing information law Email usage is ubiquitous in the modern business environment, but few companies adequately manage the risks associated with email.
- Full Text:
- Date Issued: 2003
Endothermy and chorusing behaviour in the African platypleurine cicada Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae)
- Villet, Martin H, Sanborn, Allen F, Phillips, P K
- Authors: Villet, Martin H , Sanborn, Allen F , Phillips, P K
- Date: 2003
- Language: English
- Type: text , Article
- Identifier: vital:6892 , http://hdl.handle.net/10962/d1011652 , http://dx.doi.org/10.1139/z03-119
- Description: Cicadas use acoustic signals to find mates and therefore offer a phylogenetically independent opportunity to test the generality of ideas about acoustic communication that were developed from studies of other animals. Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae) is a forest-dwelling platypleurine cicada that uses its calling song to form choruses and attract mates. Additionally, P. semiclara produces an encounter call that is involved in courtship and also in spacing males within choruses. Males generally call from exposed trunks and branches within the understory but clear of the undergrowth and fight with other males that call within about 50 cm of them. Choruses sing sporadically throughout the day but focus most of their calling activity into half-hour bouts at dawn and dusk. Body size and ambient temperature had no significant effect on spectral or temporal characteristics of the calling song. Body temperature measurements indicate that P. semiclara thermoregulates endothermically, with a body temperature of more than 22 °C above ambient temperature being measured during calling activity at dusk. Such endothermy provides an advantage to the cicadas by allowing them to call during crepuscular hours when atmospheric conditions are most optimal for acoustic communication and predation risks are minimal. Coincidentally, endogenously regulating body temperature allows the temporal characteristics of the call to be unaffected by ambient temperature changes.
- Full Text:
- Date Issued: 2003
- Authors: Villet, Martin H , Sanborn, Allen F , Phillips, P K
- Date: 2003
- Language: English
- Type: text , Article
- Identifier: vital:6892 , http://hdl.handle.net/10962/d1011652 , http://dx.doi.org/10.1139/z03-119
- Description: Cicadas use acoustic signals to find mates and therefore offer a phylogenetically independent opportunity to test the generality of ideas about acoustic communication that were developed from studies of other animals. Pycna semiclara (Germar, 1834) (Hemiptera: Cicadidae) is a forest-dwelling platypleurine cicada that uses its calling song to form choruses and attract mates. Additionally, P. semiclara produces an encounter call that is involved in courtship and also in spacing males within choruses. Males generally call from exposed trunks and branches within the understory but clear of the undergrowth and fight with other males that call within about 50 cm of them. Choruses sing sporadically throughout the day but focus most of their calling activity into half-hour bouts at dawn and dusk. Body size and ambient temperature had no significant effect on spectral or temporal characteristics of the calling song. Body temperature measurements indicate that P. semiclara thermoregulates endothermically, with a body temperature of more than 22 °C above ambient temperature being measured during calling activity at dusk. Such endothermy provides an advantage to the cicadas by allowing them to call during crepuscular hours when atmospheric conditions are most optimal for acoustic communication and predation risks are minimal. Coincidentally, endogenously regulating body temperature allows the temporal characteristics of the call to be unaffected by ambient temperature changes.
- Full Text:
- Date Issued: 2003
Environmental limits to the distribution of Scaevola plumieri along the South African coast
- Peter, Craig I, Ripley, Bradley S, Robertson, Mark P
- Authors: Peter, Craig I , Ripley, Bradley S , Robertson, Mark P
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6533 , http://hdl.handle.net/10962/d1005974
- Description: Scaevola plumieri is an important pioneer on many tropical and subtropical sand dunes, forming a large perennial subterranean plant with only the tips of the branches emerging above accreting sand. In South Africa it is the dominant pioneer on sandy beaches along the east coast, less abundant on the south coast and absent from the southwest and west coasts. Transpiration rates (E) of S. plumieri are predictably related to atmospheric vapour pressure deficit under a wide range of conditions and can therefore be predicted from measurement of ambient temperature and relative humidity. Scaling measurements of E at the leaf level to the canopy level has been demonstrated previously. Using a geographic information system, digital maps of regional climatic variables were used to calculate digital maps of potential transpiration from mean monthly temperature and relative humidity values, effectively scaling canopy level transpiration rates to a regional level. Monthly potential transpiration was subtracted from the monthly median rainfall to produce a map of mean monthly water balance. Seasonal growth was correlated with seasonal water balance. Localities along the coast with water deficits in summer corresponded with the recorded absence of S. plumieri, which grows and reproduces most actively in the summer months. This suggests that reduced water availability during the summer growth period limits the distribution of S. plumieri along the southwest coast, where water deficits develop in summer. Temperature is also important in limiting the distribution of S. plumieri on the southwest coast of South Africa through its effects on the growth and phenology of the plant.
- Full Text:
- Date Issued: 2003
- Authors: Peter, Craig I , Ripley, Bradley S , Robertson, Mark P
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6533 , http://hdl.handle.net/10962/d1005974
- Description: Scaevola plumieri is an important pioneer on many tropical and subtropical sand dunes, forming a large perennial subterranean plant with only the tips of the branches emerging above accreting sand. In South Africa it is the dominant pioneer on sandy beaches along the east coast, less abundant on the south coast and absent from the southwest and west coasts. Transpiration rates (E) of S. plumieri are predictably related to atmospheric vapour pressure deficit under a wide range of conditions and can therefore be predicted from measurement of ambient temperature and relative humidity. Scaling measurements of E at the leaf level to the canopy level has been demonstrated previously. Using a geographic information system, digital maps of regional climatic variables were used to calculate digital maps of potential transpiration from mean monthly temperature and relative humidity values, effectively scaling canopy level transpiration rates to a regional level. Monthly potential transpiration was subtracted from the monthly median rainfall to produce a map of mean monthly water balance. Seasonal growth was correlated with seasonal water balance. Localities along the coast with water deficits in summer corresponded with the recorded absence of S. plumieri, which grows and reproduces most actively in the summer months. This suggests that reduced water availability during the summer growth period limits the distribution of S. plumieri along the southwest coast, where water deficits develop in summer. Temperature is also important in limiting the distribution of S. plumieri on the southwest coast of South Africa through its effects on the growth and phenology of the plant.
- Full Text:
- Date Issued: 2003
Environmental limits to the distribution of Scaevola plumieri along the South African coast
- Peter, Craig I, Ripley, Bradley S, Robertson, Mark P
- Authors: Peter, Craig I , Ripley, Bradley S , Robertson, Mark P
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6872 , http://hdl.handle.net/10962/d1011617
- Description: Scaevola plumieri is an important pioneer on many tropical and subtropical sand dunes, forming a large perennial subterranean plant with only the tips of the branches emerging above accreting sand. In South Africa it is the dominant pioneer on sandy beaches along the east coast, less abundant on the south coast and absent from the southwest and west coasts. Transpiration rates (E) of S. plumieri are predictably related to atmospheric vapour pressure deficit under a wide range of conditions and can therefore be predicted from measurement of ambient temperature and relative humidity. Scaling measurements of E at the leaf level to the canopy level has been demonstrated previously. Using a geographic information system, digital maps of regional climatic variables were used to calculate digital maps of potential transpiration from mean monthly temperature and relative humidity values, effectively scaling canopy level transpiration rates to a regional level. Monthly potential transpiration was subtracted from the monthly median rainfall to produce a map of mean monthly water balance. Seasonal growth was correlated with seasonal water balance. Localities along the coast with water deficits in summer corresponded with the recorded absence of S. plumieri, which grows and reproduces most actively in the summer months. This suggests that reduced water availability during the summer growth period limits the distribution of S. plumieri along the southwest coast, where water deficits develop in summer. Temperature is also important in limiting the distribution of S. plumieri on the southwest coast of South Africa through its effects on the growth and phenology of the plant.
- Full Text:
- Date Issued: 2003
- Authors: Peter, Craig I , Ripley, Bradley S , Robertson, Mark P
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6872 , http://hdl.handle.net/10962/d1011617
- Description: Scaevola plumieri is an important pioneer on many tropical and subtropical sand dunes, forming a large perennial subterranean plant with only the tips of the branches emerging above accreting sand. In South Africa it is the dominant pioneer on sandy beaches along the east coast, less abundant on the south coast and absent from the southwest and west coasts. Transpiration rates (E) of S. plumieri are predictably related to atmospheric vapour pressure deficit under a wide range of conditions and can therefore be predicted from measurement of ambient temperature and relative humidity. Scaling measurements of E at the leaf level to the canopy level has been demonstrated previously. Using a geographic information system, digital maps of regional climatic variables were used to calculate digital maps of potential transpiration from mean monthly temperature and relative humidity values, effectively scaling canopy level transpiration rates to a regional level. Monthly potential transpiration was subtracted from the monthly median rainfall to produce a map of mean monthly water balance. Seasonal growth was correlated with seasonal water balance. Localities along the coast with water deficits in summer corresponded with the recorded absence of S. plumieri, which grows and reproduces most actively in the summer months. This suggests that reduced water availability during the summer growth period limits the distribution of S. plumieri along the southwest coast, where water deficits develop in summer. Temperature is also important in limiting the distribution of S. plumieri on the southwest coast of South Africa through its effects on the growth and phenology of the plant.
- Full Text:
- Date Issued: 2003
Ethics beyond the code of conduct - understanding the ethical dilemmas of entrepreneurs
- Robinson, D A, Van der Mescht, Hennie, Lancaster, Jonathan C S
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6102 , http://hdl.handle.net/10962/d1008672
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
- Full Text:
- Date Issued: 2003
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6102 , http://hdl.handle.net/10962/d1008672
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
- Full Text:
- Date Issued: 2003
Ethics beyond the code of conduct - understanding the ethical dilemmas of entrepreneurs
- Robinson, D A, Van der Mescht, Hennie, Lancaster, Jonathan C S
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6072 , http://hdl.handle.net/10962/d1001646 , ISSN 1022-2529
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
- Full Text:
- Date Issued: 2003
- Authors: Robinson, D A , Van der Mescht, Hennie , Lancaster, Jonathan C S
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: Article
- Identifier: vital:6072 , http://hdl.handle.net/10962/d1001646 , ISSN 1022-2529
- Description: Entrepreneurs choose a particular way of life with the dual aim of maximising profit and gaining a sense of self-satisfaction. In these endeavours, entrepreneurs typically live with the threat of competition and the risk of business failure, while attempting to do their best within the limitations of their resources. This qualitative study first examines existing theories of ethics and ways of applying business ethics and thereafter investigates entrepreneurs' actual experiences by means of in-depth interviews and the use of phenomenology. It finds that entrepreneurs are not guided by any specific code of conduct, and must decide for themselves what is right. It describes the entrepreneurial business ethic, some of the types of dilemmas that they experience and the methods that they have developed to deal with the dilemmas.
- Full Text:
- Date Issued: 2003
Evaluating people-environment relationships : developing appropriate research methodologies for sustainable management and rehabilitation of riverine areas by communities in the Kat River Valley, Eastern Cape Province, South Africa
- Authors: Motteux, Nicole
- Date: 2003
- Subjects: Water-supply -- South Africa -- Kat River Valley -- Management Rural development -- Environmental aspects -- South Africa -- Kat River Valley Kat River Valley (South Africa) Human ecology -- South Africa -- Kat River Valley Stream ecology -- South Africa -- Kat River Valley
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4828 , http://hdl.handle.net/10962/d1005503
- Description: International evidence clearly indicates that water shortages and the enhanced value attached to water and aquatic ecosystems are key concerns faced by many countries. International experience, since the mid-1980s, has emphasised the importance of addressing political, social, environmental and economic issues through active stakeholder participation in riverine and water resource management. These trends and issues are relevant to South Africa, where integrated water resource management (IWRM) is now a cornerstone of water resource policy and the National Water Act (NWA). Apartheid excluded communities in former homelands (racial reserves) from participation in IWRM. The research presented in this thesis was based on the search for philosophies and methods to involve the rural, former homeland people of the Kat River Valley in South Africa in IWRM. Post-modern, humanist and some logical positivist geographical philosophies were used during the research. This research applied Participatory Rural Appraisal (PRA) philosophy and methods and was influenced by the seminal work of Paolo Freire (1972). In addition, the use of innovative methods for engagement of the oppressed, using theatre methods developed by Augusto Boal (1995, 2000) was explored to add value to PRA. In addition, the application of Action Research ensured that community participants were actively involved in the research being conducted for this thesis. The applied research in the Kat River Valley in South Africa evolved through three key phases. In Phase One quantifiable data on the Kat River Valley and its residents was sought. This investigation did not empower the resident communities of Fairbairn and Hertzog – a lesson that influenced the move to more participatory methods in subsequent phases of the research. Lessons learned from using surveys encouraged exploration of participatory methods to enable participants to become “co-learners”. Phase Two of the research commenced with a series of feedback meetings, in which participants recognised that they faced an environmental crisis. Through a series of participatory workshops, residents came to acknowledge and affirm their environmental knowledge. Residents then committed themselves to gaining a deeper understanding of their environment and their lives. My role changed from that of a researcher to a facilitator. Phase Three of the research and the shift to Action Research commenced after local residents identified the need to personally take charge of their environmental challenges in the Kat River Valley and recognised the need to collaborate at a catchment scale for effective IWRM. This eventually led to the formation of a Water User Association and Catchment Forum. The key theoretical contribution of the thesis relates to the identified relationship between the development orientation and ecological paradigm, and an assessment of the impact this has on the inputs, processes, outputs and outcomes of IWRM. This theoretical contribution is equally valid in other countries, where the tradeoffs are essentially the same, but the framework for making the choices is different because of varying socio-economic and biophysical circumstances
- Full Text:
- Date Issued: 2003
- Authors: Motteux, Nicole
- Date: 2003
- Subjects: Water-supply -- South Africa -- Kat River Valley -- Management Rural development -- Environmental aspects -- South Africa -- Kat River Valley Kat River Valley (South Africa) Human ecology -- South Africa -- Kat River Valley Stream ecology -- South Africa -- Kat River Valley
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4828 , http://hdl.handle.net/10962/d1005503
- Description: International evidence clearly indicates that water shortages and the enhanced value attached to water and aquatic ecosystems are key concerns faced by many countries. International experience, since the mid-1980s, has emphasised the importance of addressing political, social, environmental and economic issues through active stakeholder participation in riverine and water resource management. These trends and issues are relevant to South Africa, where integrated water resource management (IWRM) is now a cornerstone of water resource policy and the National Water Act (NWA). Apartheid excluded communities in former homelands (racial reserves) from participation in IWRM. The research presented in this thesis was based on the search for philosophies and methods to involve the rural, former homeland people of the Kat River Valley in South Africa in IWRM. Post-modern, humanist and some logical positivist geographical philosophies were used during the research. This research applied Participatory Rural Appraisal (PRA) philosophy and methods and was influenced by the seminal work of Paolo Freire (1972). In addition, the use of innovative methods for engagement of the oppressed, using theatre methods developed by Augusto Boal (1995, 2000) was explored to add value to PRA. In addition, the application of Action Research ensured that community participants were actively involved in the research being conducted for this thesis. The applied research in the Kat River Valley in South Africa evolved through three key phases. In Phase One quantifiable data on the Kat River Valley and its residents was sought. This investigation did not empower the resident communities of Fairbairn and Hertzog – a lesson that influenced the move to more participatory methods in subsequent phases of the research. Lessons learned from using surveys encouraged exploration of participatory methods to enable participants to become “co-learners”. Phase Two of the research commenced with a series of feedback meetings, in which participants recognised that they faced an environmental crisis. Through a series of participatory workshops, residents came to acknowledge and affirm their environmental knowledge. Residents then committed themselves to gaining a deeper understanding of their environment and their lives. My role changed from that of a researcher to a facilitator. Phase Three of the research and the shift to Action Research commenced after local residents identified the need to personally take charge of their environmental challenges in the Kat River Valley and recognised the need to collaborate at a catchment scale for effective IWRM. This eventually led to the formation of a Water User Association and Catchment Forum. The key theoretical contribution of the thesis relates to the identified relationship between the development orientation and ecological paradigm, and an assessment of the impact this has on the inputs, processes, outputs and outcomes of IWRM. This theoretical contribution is equally valid in other countries, where the tradeoffs are essentially the same, but the framework for making the choices is different because of varying socio-economic and biophysical circumstances
- Full Text:
- Date Issued: 2003
Evaluation of the large-scale trapping of blowflies (Lucilia spp.) for an integrated pest management program : the lucitrap
- Authors: Scholtz, Anna J
- Date: 2003
- Subjects: Blowflies -- Control , Insect trapping , Insect traps , Pests -- Control
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10972 , http://hdl.handle.net/10948/126 , Blowflies -- Control , Insect trapping , Insect traps , Pests -- Control
- Description: The results presented in this dissertation have been partially presented at scientific meetings. Chapter 2 is an exact copy of the technical contents of a paper submitted to a scientific journal. The format of this paper however has been changed to comply with the format used in this dissertation. The results of this paper were partially presented at the 36th National Congress of the South African Society of Animal Science, 5 – 8 April 1998 held in Stellenbosch. In this chapter errors occurred in the execution of the trial, but these were corrected in the follow-up trial after consulting with the manufacturers. It is discussed in the paper. Results of chapter 3 were partially presented at the 5th International Sheep Veterinary Congress 21 – 25 January 2001 held in Stellenbosch and at an International Congress (The FLICS (Flystrike & Lice IPM Control Strategies) Conference, 25 – 27 June 2001, Launceston) in Tasmania by Mr. S.W.P. Cloete in 2001. The updated results are given in this chapter. The results of chapter 4 were presented at a combined congress between the Grasslands and the Animal Production Societies of South Africa (The GSSA/SASAS Joint Congress 2002. 13 – 16 May) in Christiana in 2002. The results in this chapter represent the same experimental period as was reported upon at that congress, but additional statistical analyses were executed on the same data set. Copies of the abstracts of the contributions to these meetings are attached in chapter 6. The major objective of this study initially was to evaluate the Lucitrap® system under South African conditions. During the experimental period I had an opportunity to visit Australia and meet many role players. It came under my attention that the control of the blowfly is a rather complex problem with many facets. A current issue worldwide on the use of chemicals as a control method against insects and its hazardous influence on the environment is forcing producers to minimize chemical residues in textiles and other agricultural products. An Integrated Pest Management (IPM) approach seems to be the only option. This study has been executed to try and understand some aspects of the blowfly problem for future application in such a blowfly control program.
- Full Text:
- Date Issued: 2003
- Authors: Scholtz, Anna J
- Date: 2003
- Subjects: Blowflies -- Control , Insect trapping , Insect traps , Pests -- Control
- Language: English
- Type: Thesis , Masters , MTech (Agricultural Management)
- Identifier: vital:10972 , http://hdl.handle.net/10948/126 , Blowflies -- Control , Insect trapping , Insect traps , Pests -- Control
- Description: The results presented in this dissertation have been partially presented at scientific meetings. Chapter 2 is an exact copy of the technical contents of a paper submitted to a scientific journal. The format of this paper however has been changed to comply with the format used in this dissertation. The results of this paper were partially presented at the 36th National Congress of the South African Society of Animal Science, 5 – 8 April 1998 held in Stellenbosch. In this chapter errors occurred in the execution of the trial, but these were corrected in the follow-up trial after consulting with the manufacturers. It is discussed in the paper. Results of chapter 3 were partially presented at the 5th International Sheep Veterinary Congress 21 – 25 January 2001 held in Stellenbosch and at an International Congress (The FLICS (Flystrike & Lice IPM Control Strategies) Conference, 25 – 27 June 2001, Launceston) in Tasmania by Mr. S.W.P. Cloete in 2001. The updated results are given in this chapter. The results of chapter 4 were presented at a combined congress between the Grasslands and the Animal Production Societies of South Africa (The GSSA/SASAS Joint Congress 2002. 13 – 16 May) in Christiana in 2002. The results in this chapter represent the same experimental period as was reported upon at that congress, but additional statistical analyses were executed on the same data set. Copies of the abstracts of the contributions to these meetings are attached in chapter 6. The major objective of this study initially was to evaluate the Lucitrap® system under South African conditions. During the experimental period I had an opportunity to visit Australia and meet many role players. It came under my attention that the control of the blowfly is a rather complex problem with many facets. A current issue worldwide on the use of chemicals as a control method against insects and its hazardous influence on the environment is forcing producers to minimize chemical residues in textiles and other agricultural products. An Integrated Pest Management (IPM) approach seems to be the only option. This study has been executed to try and understand some aspects of the blowfly problem for future application in such a blowfly control program.
- Full Text:
- Date Issued: 2003
Evolution of a strongly differentiated suite of phonolites from the Klinghardt Mountains, Namibia
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140400 , vital:37885 , https://doi.org/10.1016/0024-4937(87)90023-5
- Description: Phonolites of Tertiary age occur as eroded tholoids, lava flows, ignimbrites, and coulees in the Klinghardt Mountains of southern Namibia. Sixty samples have been analyzed for major and trace elements and fourteen of these for 87SR 86SR. The phonolites lie close to the low-pressure cotectics in Q-Ne-Ks, in keeping with their petrography which indicates that most samples have phenocrysts of both nepheline and sanidine. Na has been variably lost from the rocks during crystallization and devitrification/alteration of hypocrystalline specimens.
- Full Text: false
- Date Issued: 2003
- Authors: Marsh, Julian S
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140400 , vital:37885 , https://doi.org/10.1016/0024-4937(87)90023-5
- Description: Phonolites of Tertiary age occur as eroded tholoids, lava flows, ignimbrites, and coulees in the Klinghardt Mountains of southern Namibia. Sixty samples have been analyzed for major and trace elements and fourteen of these for 87SR 86SR. The phonolites lie close to the low-pressure cotectics in Q-Ne-Ks, in keeping with their petrography which indicates that most samples have phenocrysts of both nepheline and sanidine. Na has been variably lost from the rocks during crystallization and devitrification/alteration of hypocrystalline specimens.
- Full Text: false
- Date Issued: 2003
Exploring differences between organisational cultures in a company undergoing change
- Authors: Bowa, Mabvuto
- Date: 2003
- Subjects: Organizational change -- Africa , Corporate culture -- Africa , Management -- Africa , Organizational behavior -- Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3126 , http://hdl.handle.net/10962/d1006287 , Organizational change -- Africa , Corporate culture -- Africa , Management -- Africa , Organizational behavior -- Africa
- Description: Change is a common phenomena in business organisations today. The turbulent environment is exerting a significant influence on organisations to make continuous changes in their internal environment in an attempt to improve performance and achieve competitiveness in the marketplace. The human factors which confront organisations undergoing change have not been thoroughly investigated in Sub-Saharan Africa. The present study aimed at investigating human issues affecting the performance ofan organisation located in an Afiican country. Data was collected using semi-structured interviews and focus groups. Twenty interviews were conducted with employees randomly selected from all the levels of the company, namely attendant, operator, supervisory, middle and top management. Five focus groups were carried out with employees from different employee categories. Both sets of data were analysed using grounded theory. The findings showed that there were several problems in the company including insecurity, lack of opportunities for employee development, autocratic management style, lack of participation in decision making, substandard performance, ineffective human resources systems and lack of adaptation to technology. It was suggested that the problems resulted from the clash between organisational cultures in the company. At one level, there was a clash between the local workers' socialist organisational culture and the expatriates' capitalistic organisational culture. At a more deeper level, the clash appeared to be between the local employees' collectivistic sociocultural values and the expatriates' individualistic value system. These findings have significant implications for managing change in organisations with diverse cultures.
- Full Text:
- Date Issued: 2003
- Authors: Bowa, Mabvuto
- Date: 2003
- Subjects: Organizational change -- Africa , Corporate culture -- Africa , Management -- Africa , Organizational behavior -- Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3126 , http://hdl.handle.net/10962/d1006287 , Organizational change -- Africa , Corporate culture -- Africa , Management -- Africa , Organizational behavior -- Africa
- Description: Change is a common phenomena in business organisations today. The turbulent environment is exerting a significant influence on organisations to make continuous changes in their internal environment in an attempt to improve performance and achieve competitiveness in the marketplace. The human factors which confront organisations undergoing change have not been thoroughly investigated in Sub-Saharan Africa. The present study aimed at investigating human issues affecting the performance ofan organisation located in an Afiican country. Data was collected using semi-structured interviews and focus groups. Twenty interviews were conducted with employees randomly selected from all the levels of the company, namely attendant, operator, supervisory, middle and top management. Five focus groups were carried out with employees from different employee categories. Both sets of data were analysed using grounded theory. The findings showed that there were several problems in the company including insecurity, lack of opportunities for employee development, autocratic management style, lack of participation in decision making, substandard performance, ineffective human resources systems and lack of adaptation to technology. It was suggested that the problems resulted from the clash between organisational cultures in the company. At one level, there was a clash between the local workers' socialist organisational culture and the expatriates' capitalistic organisational culture. At a more deeper level, the clash appeared to be between the local employees' collectivistic sociocultural values and the expatriates' individualistic value system. These findings have significant implications for managing change in organisations with diverse cultures.
- Full Text:
- Date Issued: 2003
External and domestic sources of foreign policy ambiguity: South African foreign policy and the projection of pluralist middle power
- Authors: Bischoff, Paul, 1954-
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161442 , vital:40627 , https://doi.org/10.1080/0258934032000147291
- Description: As a pluralist middle power, post-apartheid South Africa seeks to generate successful foreign policy initiatives at bilateral, multilateral and regional levels in order to shape international outcomes. In this endeavour, it has three important political resources – a recognition of its geo-political position and importance as a democratic yardstick and reformer; its acceptance of a transnational, neo-liberal elite alliance and finally, recognition of its leadership role from forces wishing to challenge African political establishments. However, the international and domestic political environment which in the mid-1990s was favourable towards middle-power initiative and reform has narrowed.
- Full Text:
- Date Issued: 2003
- Authors: Bischoff, Paul, 1954-
- Date: 2003
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/161442 , vital:40627 , https://doi.org/10.1080/0258934032000147291
- Description: As a pluralist middle power, post-apartheid South Africa seeks to generate successful foreign policy initiatives at bilateral, multilateral and regional levels in order to shape international outcomes. In this endeavour, it has three important political resources – a recognition of its geo-political position and importance as a democratic yardstick and reformer; its acceptance of a transnational, neo-liberal elite alliance and finally, recognition of its leadership role from forces wishing to challenge African political establishments. However, the international and domestic political environment which in the mid-1990s was favourable towards middle-power initiative and reform has narrowed.
- Full Text:
- Date Issued: 2003
Finite element modelling of a magma chamber surrounded by country-rock, with particular reference to the groundwater flow in sections of different permeability
- Authors: Remsing, Carmen
- Date: 2003 , 2013-05-23
- Subjects: Magmas , Groundwater flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5508 , http://hdl.handle.net/10962/d1007537 , Magmas , Groundwater flow
- Description: This thesis presents results of two-dimensional finite element modelling of a magma chamber surrounded by country-rock containing a section of high permeability. The high permeability section in the country-rock simulates structure that is predominant in controlling the groundwater convection pattern and resulting mineral deposits. The models have analogies in nature: for instance the gold mines in the Massif Central of France, the Pogo mine in Alaska and the Pilgrim's Rest gold field in South Africa. This is a complicated coupled system involving fluid flow and heat transfer under extreme conditions. The magma in the chamber convects and as it cools the heat liberated causes convection in the groundwater contained in the surrounding country-rock. This convection in turn affects the rate of liberation of heat from the magma. The software used for the modelling, FLOTRAN, is the computational fluid dynamics component of the commercial ANSYS package. The results obtained describe in detail the flow pattern in the magma chamber, the country-rock and high permeability section thereof. During the cooling of the magma chamber the groundwater convects more vigorously in the high permeability section than elsewhere, and a convection cell is seen forming within this region. This provides a mechanism for hydrothermal formation of valuable mineral deposits in the structure near a magma chamber. It is found that the relationship between the velocity of the flow in the cell and the temperature of the magma chamber is well represented by a first order linear differential equation, providing a simple understanding of this process, , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
- Authors: Remsing, Carmen
- Date: 2003 , 2013-05-23
- Subjects: Magmas , Groundwater flow
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5508 , http://hdl.handle.net/10962/d1007537 , Magmas , Groundwater flow
- Description: This thesis presents results of two-dimensional finite element modelling of a magma chamber surrounded by country-rock containing a section of high permeability. The high permeability section in the country-rock simulates structure that is predominant in controlling the groundwater convection pattern and resulting mineral deposits. The models have analogies in nature: for instance the gold mines in the Massif Central of France, the Pogo mine in Alaska and the Pilgrim's Rest gold field in South Africa. This is a complicated coupled system involving fluid flow and heat transfer under extreme conditions. The magma in the chamber convects and as it cools the heat liberated causes convection in the groundwater contained in the surrounding country-rock. This convection in turn affects the rate of liberation of heat from the magma. The software used for the modelling, FLOTRAN, is the computational fluid dynamics component of the commercial ANSYS package. The results obtained describe in detail the flow pattern in the magma chamber, the country-rock and high permeability section thereof. During the cooling of the magma chamber the groundwater convects more vigorously in the high permeability section than elsewhere, and a convection cell is seen forming within this region. This provides a mechanism for hydrothermal formation of valuable mineral deposits in the structure near a magma chamber. It is found that the relationship between the velocity of the flow in the cell and the temperature of the magma chamber is well represented by a first order linear differential equation, providing a simple understanding of this process, , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2003
Foam drug delivery in dermatology: beyond the scalp
- Purdon, Carryn H, Haigh, John M, Surber, Christian, Smith, Eric W
- Authors: Purdon, Carryn H , Haigh, John M , Surber, Christian , Smith, Eric W
- Date: 2003
- Subjects: Adis International Limited , Drug delivery systems , Skin disorders
- Language: English
- Type: text , Article
- Identifier: vital:6418 , http://hdl.handle.net/10962/d1006541
- Description: Consumers of topical formulations apply a wide spectrum of preparations, both cosmetic and dermatological, to their healthy or diseased skin. These formulations range in physicochemical nature from solid through semisolid to liquid. Pharmaceutical foams are pressurized dosage forms containing one or more active ingredients that, upon valve actuation, emit a fine dispersion of liquid and/or solid materials in a gaseous medium. Foam formulations are generally easier to apply, are less dense, and spread more easily than other topical dosage forms. Foams may be formulated in various ways to provide emollient or drying functions to the skin, depending on the formulation constituents. Therefore, this delivery technology should be a useful addition to the spectrum of formulations available for topical use; however, as yet, only a few are commercially available. Probably the most convincing argument for the use of foams is ease of use by the patient, and consumer acceptance. Most foam dosage forms used in dermatology to date have incorporated corticosteroids, although some products have also been used to deliver antiseptics, antifungal agents, anti-inflammatory agents, local anesthetic agents, skin emollients, and protectants. Although there is no clinical evidence that foam formulations are currently superior to other conventional delivery vehicles, these formulations have a clear application advantage and with continued developments in the science of supersaturation technology, it seems certain that foam delivery systems will retain their place in the dermatological and cosmetic armamentarium.
- Full Text:
- Date Issued: 2003
- Authors: Purdon, Carryn H , Haigh, John M , Surber, Christian , Smith, Eric W
- Date: 2003
- Subjects: Adis International Limited , Drug delivery systems , Skin disorders
- Language: English
- Type: text , Article
- Identifier: vital:6418 , http://hdl.handle.net/10962/d1006541
- Description: Consumers of topical formulations apply a wide spectrum of preparations, both cosmetic and dermatological, to their healthy or diseased skin. These formulations range in physicochemical nature from solid through semisolid to liquid. Pharmaceutical foams are pressurized dosage forms containing one or more active ingredients that, upon valve actuation, emit a fine dispersion of liquid and/or solid materials in a gaseous medium. Foam formulations are generally easier to apply, are less dense, and spread more easily than other topical dosage forms. Foams may be formulated in various ways to provide emollient or drying functions to the skin, depending on the formulation constituents. Therefore, this delivery technology should be a useful addition to the spectrum of formulations available for topical use; however, as yet, only a few are commercially available. Probably the most convincing argument for the use of foams is ease of use by the patient, and consumer acceptance. Most foam dosage forms used in dermatology to date have incorporated corticosteroids, although some products have also been used to deliver antiseptics, antifungal agents, anti-inflammatory agents, local anesthetic agents, skin emollients, and protectants. Although there is no clinical evidence that foam formulations are currently superior to other conventional delivery vehicles, these formulations have a clear application advantage and with continued developments in the science of supersaturation technology, it seems certain that foam delivery systems will retain their place in the dermatological and cosmetic armamentarium.
- Full Text:
- Date Issued: 2003
Food choices of tactile defensive children
- Authors: Smith, Anna Magdalena
- Date: 2003
- Subjects: Children -- Nutrition -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11034 , http://hdl.handle.net/10948/d1020371
- Description: This research explores a different view of the picky or fussy eater. Although occupational therapists and speech therapists are aware that children with sensory defensiveness and specific tactile defensiveness have different eating habits, this has not been described before.
- Full Text:
- Date Issued: 2003
- Authors: Smith, Anna Magdalena
- Date: 2003
- Subjects: Children -- Nutrition -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11034 , http://hdl.handle.net/10948/d1020371
- Description: This research explores a different view of the picky or fussy eater. Although occupational therapists and speech therapists are aware that children with sensory defensiveness and specific tactile defensiveness have different eating habits, this has not been described before.
- Full Text:
- Date Issued: 2003
From labour reserve to investment opportunity: economic development planning in the Mbashe Local Municipal area in the Eastern Cape
- Authors: Reynolds, John Hunter
- Date: 2003
- Subjects: Economic development -- South Africa -- Eastern Cape , Community development -- South Africa -- Eastern Cape , South Africa -- Economic policy , Planning -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3353 , http://hdl.handle.net/10962/d1007490 , Economic development -- South Africa -- Eastern Cape , Community development -- South Africa -- Eastern Cape , South Africa -- Economic policy , Planning -- South Africa -- Eastern Cape
- Description: Planning for economic development at the local level has become increasingly important in many countries of the world. South Africa is no exception and has had the local focus entrenched through constitutional provisions for developmental local government. This developmental approach has been intimately linked to, and influenced by, the broader legislative, policy and planning context within which the development challenges of post-Apartheid South Africa have been addressed. It has also been implemented in a context of far-reaching transformation of public institutions aimed, in the final analysis, at the effective functioning of three spheres of government. In this thesis, the Mbashe Local Municipal area is used as a case study for an examination of the linkages between economic development planning at the local, provincial and national levels. It is not a case study in the sense that an in-depth analysis of practice is undertaken; it is used rather as a lens through which the economic development planning activities of the three spheres of government are viewed. Its value as a lens lies in its location in the former Transkei, which is characterised by high levels of unemployment and poverty and low levels of service infrastructure, and in its status as one of the newly demarcated local municipalities in South Africa. Mbashe is a pilot site of the Promotion of Rural Livelihoods Programme, which has been linked to the Eastern Cape Province's Integrated Sustainable Rural Development Programme. It also includes one of the nodes of the Wild Coast Spatial Development Initiative, which has, since 1998, been promoted as a vehicle for economic development in the former Transkei. Research comprised extensive documentary research, individual interviews with key role players in the Mbashe Local Municipality, the Promotion of Rural Livelihoods Programme and the Wild Coast Spatial Development Initiative, and a group interview with members of the Local Economic Development Sub-Committee of the Mbashe Local Municipal Council. An attempt was made to understand the complex layers of policy and planning frameworks that guide planning at the national and provincial levels and within which local level economic development is situated, and to explore the responses that have been forged by agents within the Mbashe area. Key in this endeavour has been the initiatives developed under the guidance of the Mbashe Local Economic Development Sub-Committee. It is argued that the severe resource constraints faced within Mbashe, combined with limited knowledge of and participation in larger planning and resource mobilisation frameworks, lock Local Economic Development within the top-down and investmentled approaches, rather than the more integrated approach that is promoted in terms of legislation and that is required if poverty is to be addressed successfully. The limitations on state fiscal expenditure and the market-led approach to service provision and economic development, implemented in terms of South Africa's macroeconomic framework, combined with limited synchronisation of planning cycles in which integrated development planning at the local level is privileged, leave little scope for endogenous economic development at local level. There is scope for creative engagement with the interlocking local, provincial, national and continental economies by actively shifting resources in support of integrated, endogenous approaches. Such approaches could serve as counter-narratives to the dominance of neoliberalism and allow for the establishment of local economic development practice that addresses the needs of the poor and that builds integrated local economies under the control of democratic institutions. It is only with such a shifting of approach that economic development within Mbashe will shift the structural conditions that lock it into economic dependence and poverty.
- Full Text:
- Date Issued: 2003
- Authors: Reynolds, John Hunter
- Date: 2003
- Subjects: Economic development -- South Africa -- Eastern Cape , Community development -- South Africa -- Eastern Cape , South Africa -- Economic policy , Planning -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3353 , http://hdl.handle.net/10962/d1007490 , Economic development -- South Africa -- Eastern Cape , Community development -- South Africa -- Eastern Cape , South Africa -- Economic policy , Planning -- South Africa -- Eastern Cape
- Description: Planning for economic development at the local level has become increasingly important in many countries of the world. South Africa is no exception and has had the local focus entrenched through constitutional provisions for developmental local government. This developmental approach has been intimately linked to, and influenced by, the broader legislative, policy and planning context within which the development challenges of post-Apartheid South Africa have been addressed. It has also been implemented in a context of far-reaching transformation of public institutions aimed, in the final analysis, at the effective functioning of three spheres of government. In this thesis, the Mbashe Local Municipal area is used as a case study for an examination of the linkages between economic development planning at the local, provincial and national levels. It is not a case study in the sense that an in-depth analysis of practice is undertaken; it is used rather as a lens through which the economic development planning activities of the three spheres of government are viewed. Its value as a lens lies in its location in the former Transkei, which is characterised by high levels of unemployment and poverty and low levels of service infrastructure, and in its status as one of the newly demarcated local municipalities in South Africa. Mbashe is a pilot site of the Promotion of Rural Livelihoods Programme, which has been linked to the Eastern Cape Province's Integrated Sustainable Rural Development Programme. It also includes one of the nodes of the Wild Coast Spatial Development Initiative, which has, since 1998, been promoted as a vehicle for economic development in the former Transkei. Research comprised extensive documentary research, individual interviews with key role players in the Mbashe Local Municipality, the Promotion of Rural Livelihoods Programme and the Wild Coast Spatial Development Initiative, and a group interview with members of the Local Economic Development Sub-Committee of the Mbashe Local Municipal Council. An attempt was made to understand the complex layers of policy and planning frameworks that guide planning at the national and provincial levels and within which local level economic development is situated, and to explore the responses that have been forged by agents within the Mbashe area. Key in this endeavour has been the initiatives developed under the guidance of the Mbashe Local Economic Development Sub-Committee. It is argued that the severe resource constraints faced within Mbashe, combined with limited knowledge of and participation in larger planning and resource mobilisation frameworks, lock Local Economic Development within the top-down and investmentled approaches, rather than the more integrated approach that is promoted in terms of legislation and that is required if poverty is to be addressed successfully. The limitations on state fiscal expenditure and the market-led approach to service provision and economic development, implemented in terms of South Africa's macroeconomic framework, combined with limited synchronisation of planning cycles in which integrated development planning at the local level is privileged, leave little scope for endogenous economic development at local level. There is scope for creative engagement with the interlocking local, provincial, national and continental economies by actively shifting resources in support of integrated, endogenous approaches. Such approaches could serve as counter-narratives to the dominance of neoliberalism and allow for the establishment of local economic development practice that addresses the needs of the poor and that builds integrated local economies under the control of democratic institutions. It is only with such a shifting of approach that economic development within Mbashe will shift the structural conditions that lock it into economic dependence and poverty.
- Full Text:
- Date Issued: 2003
Fuelwood availability and use in the Richtersveld National Park, South Africa
- Shackleton, Charlie M, Guthrie, G, Keirungi, J, Stewart, J
- Authors: Shackleton, Charlie M , Guthrie, G , Keirungi, J , Stewart, J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181461 , vital:43736 , xlink:href=" https://doi.org/10.4102/koedoe.v46i2.66"
- Description: Concern has been voiced about the possible over-use of fuelwood from the riparian fringe by pastoralist herders in the Richtersveld National Park (RNP). This coincided with the current examination and modelling of the supply and use of ecosystem goods and services in the Gariep Basin as part of the Southern African Millennium Assessment (SAfMA). This paper reports on a study to index the current availability of deadwood within the riparian zone of RNP, its relationship with proximity to human habitation, and species preferences of the local herders. Deadwood availability was assessed per woody species and on the ground in 12 transects within the riparian fringe. Herders were interviewed regarding their species preferences, and the composition of woodpiles was examined. There was no relationship between the percentage of attached deadwood on the tree, or the percentage deadwood ground cover, and the distance from herder stockposts. Euclea pseudobenus and Tamarix usneoides were the dominant species in the riparian fringe. There was strong selection for Ziziphus mucronata as a fuelwood species and only marginal or random selection for E. pseudobenus. Tamarix usneoides and Prosopis sp. were abundant in the riparian zone, but were not used for fuelwood. There was a significant difference between species with respect to the mean proportion of the stem that was dead, the highest being Z. mucronata (± 28 % deadwood), followed by T. usneoides (± 12 %). Most of the Prosopis trees had no deadwood. Across all species, the mean percentage dead per tree was approximately 15 %. Additionally, detached deadwood covered just less than 9 % of ground area, averaged across all plots and transects. All the variables measured indicated that there seems to be little need for concern over the current fuelwood extraction activities of pastoralists within the RNP. There was no clear evidence of cutting of branches or deadwood. The abundance of both attached and detached deadwood was not depleted close to human habitation. There was still abundant deadwood, even on preferred species. The most preferred species (Ziziphus mucronata) had the greatest mean proportion of deadwood. The herders stated that they only used deadwood, and that there was plenty. They rarely used driftwood washed down the river, although there was an abundance of it. Thus, overall, there was no sign of depletion of the deadwood resource, even on favoured species, or degradation of the productive capacity for deadwood.
- Full Text:
- Date Issued: 2003
- Authors: Shackleton, Charlie M , Guthrie, G , Keirungi, J , Stewart, J
- Date: 2003
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181461 , vital:43736 , xlink:href=" https://doi.org/10.4102/koedoe.v46i2.66"
- Description: Concern has been voiced about the possible over-use of fuelwood from the riparian fringe by pastoralist herders in the Richtersveld National Park (RNP). This coincided with the current examination and modelling of the supply and use of ecosystem goods and services in the Gariep Basin as part of the Southern African Millennium Assessment (SAfMA). This paper reports on a study to index the current availability of deadwood within the riparian zone of RNP, its relationship with proximity to human habitation, and species preferences of the local herders. Deadwood availability was assessed per woody species and on the ground in 12 transects within the riparian fringe. Herders were interviewed regarding their species preferences, and the composition of woodpiles was examined. There was no relationship between the percentage of attached deadwood on the tree, or the percentage deadwood ground cover, and the distance from herder stockposts. Euclea pseudobenus and Tamarix usneoides were the dominant species in the riparian fringe. There was strong selection for Ziziphus mucronata as a fuelwood species and only marginal or random selection for E. pseudobenus. Tamarix usneoides and Prosopis sp. were abundant in the riparian zone, but were not used for fuelwood. There was a significant difference between species with respect to the mean proportion of the stem that was dead, the highest being Z. mucronata (± 28 % deadwood), followed by T. usneoides (± 12 %). Most of the Prosopis trees had no deadwood. Across all species, the mean percentage dead per tree was approximately 15 %. Additionally, detached deadwood covered just less than 9 % of ground area, averaged across all plots and transects. All the variables measured indicated that there seems to be little need for concern over the current fuelwood extraction activities of pastoralists within the RNP. There was no clear evidence of cutting of branches or deadwood. The abundance of both attached and detached deadwood was not depleted close to human habitation. There was still abundant deadwood, even on preferred species. The most preferred species (Ziziphus mucronata) had the greatest mean proportion of deadwood. The herders stated that they only used deadwood, and that there was plenty. They rarely used driftwood washed down the river, although there was an abundance of it. Thus, overall, there was no sign of depletion of the deadwood resource, even on favoured species, or degradation of the productive capacity for deadwood.
- Full Text:
- Date Issued: 2003