Description and identification of white grubs (Coleoptera: Scarabaeidae) attacking pineapple crops in South Africa
- Smith, Tamara J, Petty, G, Villet, Martin H
- Authors: Smith, Tamara J , Petty, G , Villet, Martin H
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6853 , http://hdl.handle.net/10962/d1011134
- Description: Larvae of five species of scarabaeid beetles, Asthenopholis subfasciata Blanchard, Trochalus politus Moser, Macrophylla ciliata Herbst, Congela valida Peringuey and Adoretus ictericus Burmeister, and adults of a sixth species, Heteronychus arator (Fabricius), cause considerable economic damage to the root systems of pineapple plants. The biologies of the species differ, making reliable identification essential. Since no convenient method is available to identify them, both field and laboratory keys are provided for the identification of third instar larvae of the six species, and detailed, illustrated descriptions for confirming their identifications
- Full Text:
- Date Issued: 1995
- Authors: Smith, Tamara J , Petty, G , Villet, Martin H
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6853 , http://hdl.handle.net/10962/d1011134
- Description: Larvae of five species of scarabaeid beetles, Asthenopholis subfasciata Blanchard, Trochalus politus Moser, Macrophylla ciliata Herbst, Congela valida Peringuey and Adoretus ictericus Burmeister, and adults of a sixth species, Heteronychus arator (Fabricius), cause considerable economic damage to the root systems of pineapple plants. The biologies of the species differ, making reliable identification essential. Since no convenient method is available to identify them, both field and laboratory keys are provided for the identification of third instar larvae of the six species, and detailed, illustrated descriptions for confirming their identifications
- Full Text:
- Date Issued: 1995
Hydroclimatic trends, sediment sources and geomorphic response in the Bell River catchment, eastern Cape Drakensberg, South Africa
- Dollar, Evan S J, Rowntree, Kate M
- Authors: Dollar, Evan S J , Rowntree, Kate M
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6677 , http://hdl.handle.net/10962/d1006655
- Description: The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.
- Full Text:
- Date Issued: 1995
- Authors: Dollar, Evan S J , Rowntree, Kate M
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6677 , http://hdl.handle.net/10962/d1006655
- Description: The Bell River in the Eastern Cape Drakensberg of South Africa has shown recent signs of channel instability as evidenced by avulsion, sinuosity reductions, gradient steepening and general channel instability. Analysis of rainfall data did not provide evidence for progressive long term change in rainfall pattern for the catchment. However, annual and seasonal rainfall cycles with variance peaks every 16-19 years were found, from which it can be inferred that flood events following years of below average rainfall may cross the threshold limit for channel stability. Channel instability is often followed by a major flood event after sustained low rainfall periods, a sequence referred to as the Flood and Drought Dominated Regimes by Warner (1987). Evidence presented also indicates an increase in catchment erosion in the past century with attendant sediment production increases to the channel. This may be due to catchment land use and management practices (following settlement by commercial farmers) superimposed on long term climatic changes. The conclusions are that catchment and channel processes are inseparable, and that disequilibrium in the catchment will be transferred to the channel.
- Full Text:
- Date Issued: 1995
Sensitive high-performance liquid chromatographic determination of cyclizine and its demethylated metabolite, norcyclizine, in biological fluids using coulometric detection
- Walker, Roderick B, Kanfer, Isadore
- Authors: Walker, Roderick B , Kanfer, Isadore
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6452 , http://hdl.handle.net/10962/d1006640 , http://dx.doi.org/10.1016/0378-4347(95)00202-T
- Description: An accurate, sensitive, selective and reproducible high-performance liquid chromatographic method with coulometric detection for the determination of cyclizine and its inactive demethylated metabolite, norcyclizine, in biological fluids has been developed. The drugs were separated using a custom packed reversed-phase C18 analytical column and phosphate buffer (0.05 M, pH 3)-acetonitrile (7:3) as mobile phase. The dual electrode coulometric detector was operated in the "oxidative-screen" mode with the upstream electrode (detector 1) set at 0.55 V and the downstream electrode (detector 2) set at 0.90 V. Serum and urine samples were prepared for analysis by solid-phase extraction, followed by a simple phase-separation step. The limit of quantitation was 1 ng/ml for both cyclizine and norcyclizine in serum and urine.
- Full Text:
- Date Issued: 1995
- Authors: Walker, Roderick B , Kanfer, Isadore
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6452 , http://hdl.handle.net/10962/d1006640 , http://dx.doi.org/10.1016/0378-4347(95)00202-T
- Description: An accurate, sensitive, selective and reproducible high-performance liquid chromatographic method with coulometric detection for the determination of cyclizine and its inactive demethylated metabolite, norcyclizine, in biological fluids has been developed. The drugs were separated using a custom packed reversed-phase C18 analytical column and phosphate buffer (0.05 M, pH 3)-acetonitrile (7:3) as mobile phase. The dual electrode coulometric detector was operated in the "oxidative-screen" mode with the upstream electrode (detector 1) set at 0.55 V and the downstream electrode (detector 2) set at 0.90 V. Serum and urine samples were prepared for analysis by solid-phase extraction, followed by a simple phase-separation step. The limit of quantitation was 1 ng/ml for both cyclizine and norcyclizine in serum and urine.
- Full Text:
- Date Issued: 1995
The discourse of postgraduate seminars
- Authors: De Klerk, Vivian A
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6132 , http://hdl.handle.net/10962/d1011584
- Description: Video recordings of a range of postgraduate seminars in the Arts Faculty at a South African university were made and analyzed, in order to define the current nature of this particular form of educational practice in South African tertiary institutions. Recent demographic changes in formerly White universities are having a significant effect on the nature of interaction in formal discussion groups. Despite a common perception that at a tertiary level tutors and students are equally entitled to speak and all contributions equally valued, this article reveals that postgraduate seminars are sites of competition for the floor and that there are significant imbalances in participation by different groups in this competitive speaking environment; it is further argued that these imbalances reflect different (culture- and gender-specific) assumptions about what constitutes appropriate participation and also, to some degree, previous learned discourse patterns associated with schooling experience.
- Full Text:
- Date Issued: 1995
- Authors: De Klerk, Vivian A
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6132 , http://hdl.handle.net/10962/d1011584
- Description: Video recordings of a range of postgraduate seminars in the Arts Faculty at a South African university were made and analyzed, in order to define the current nature of this particular form of educational practice in South African tertiary institutions. Recent demographic changes in formerly White universities are having a significant effect on the nature of interaction in formal discussion groups. Despite a common perception that at a tertiary level tutors and students are equally entitled to speak and all contributions equally valued, this article reveals that postgraduate seminars are sites of competition for the floor and that there are significant imbalances in participation by different groups in this competitive speaking environment; it is further argued that these imbalances reflect different (culture- and gender-specific) assumptions about what constitutes appropriate participation and also, to some degree, previous learned discourse patterns associated with schooling experience.
- Full Text:
- Date Issued: 1995
The effect of fluctuating substrate salinity on the yield and flag leaf photosynthesis of wheat
- Beckett, R P, Drennan, P M, Botha, Christiaan E J
- Authors: Beckett, R P , Drennan, P M , Botha, Christiaan E J
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6501 , http://hdl.handle.net/10962/d1005922
- Description: The effects of constant and fluctuating substrate salinity on flag leaf photosynthesis and grain yield of wheat were investigated. Plants exposed to salinity fluctuating around a mean integrated value of 25 mol m-3 NaCl (0-50 mol m-3) and around 50 mol m-3 NaCl (25-75 mol m-3) had yields 36 and 38% higher, respectively, than those receiving the corresponding constant salinity. Plants treated with salinity fluctuating from 50-100 mol m-3 NaCl had a 14% lower yield than those receiving 75 mol m-3 NaCl. Flag leaf photosynthesis did not vary between treatments and during salinity fluctuations, suggesting that differences in flag leaf longevity caused the observed differences in yield. Results suggest plants grown under constant salinity are unlikely to behave as those in field situations, where fluctuating rather than constant salinity occurs.
- Full Text: false
- Date Issued: 1995
- Authors: Beckett, R P , Drennan, P M , Botha, Christiaan E J
- Date: 1995
- Language: English
- Type: Article
- Identifier: vital:6501 , http://hdl.handle.net/10962/d1005922
- Description: The effects of constant and fluctuating substrate salinity on flag leaf photosynthesis and grain yield of wheat were investigated. Plants exposed to salinity fluctuating around a mean integrated value of 25 mol m-3 NaCl (0-50 mol m-3) and around 50 mol m-3 NaCl (25-75 mol m-3) had yields 36 and 38% higher, respectively, than those receiving the corresponding constant salinity. Plants treated with salinity fluctuating from 50-100 mol m-3 NaCl had a 14% lower yield than those receiving 75 mol m-3 NaCl. Flag leaf photosynthesis did not vary between treatments and during salinity fluctuations, suggesting that differences in flag leaf longevity caused the observed differences in yield. Results suggest plants grown under constant salinity are unlikely to behave as those in field situations, where fluctuating rather than constant salinity occurs.
- Full Text: false
- Date Issued: 1995
The effects of elevated and ambient temperature conditions on dilutions of fluocinolone acetonide ointment assessed using the human skin-blanching assay
- Haigh, John M, Smith, Eric W
- Authors: Haigh, John M , Smith, Eric W
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6380 , http://hdl.handle.net/10962/d1006298
- Description: Topical corticosteroid formulations have been in use now for some 30 years and many methods are available for the in vivo assessment of these preparations. Of all the assays described in the literature, the one first advocated by McKenzie and Stoughton, the so-called vasoconstrictor assay, is one of the most reliable if performed by experienced researchers using - the optimised methodology. Topical application of corticosteroids produces a whitening (blanching) of the skin, the intensity of which is directly proportional to the clinical efficacy of the formulation. Assessment of the degree of blanching produced is therefore of use in determining the rate and extent of corticosteroid release' from the semi-solid base through the stratum corneum. Since it is the degree of blanching which is measured, we prefer to call this test the human skin blanching assay. Some of the main advantages of this assay technique are that normal healthy skin is used therefore persons with dermatological complaints are not compromised, it is not painful for the volunteers, it is non-invasive and several formulations can be evaluated simultaneously. Most commercially available topical corticosteroid preparations have been formulated in such a way as to provide optimum release of the active ingredient from the base through the stratum corneum. Despite this fact, many practitioners often prescribe dilutions of topical corticosteroid formulations, presumably in an effort to reduce the unwanted side effects. This could be problematic; dilution with an incompatible base could destroy the delivery environment thus considerably reducing the efficacy of the formulation. The method of dilution could also play a role in the suitability of the final preparation. The objective of this work was to determine the effects of two different dilutions of fluocinolone ointment at both ambient and elevated temperature on the blanching produced by the dilutions and, by inference, the relative clinical efficacies of these dilutions compared to the full strength product.
- Full Text:
- Date Issued: 1995
- Authors: Haigh, John M , Smith, Eric W
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6380 , http://hdl.handle.net/10962/d1006298
- Description: Topical corticosteroid formulations have been in use now for some 30 years and many methods are available for the in vivo assessment of these preparations. Of all the assays described in the literature, the one first advocated by McKenzie and Stoughton, the so-called vasoconstrictor assay, is one of the most reliable if performed by experienced researchers using - the optimised methodology. Topical application of corticosteroids produces a whitening (blanching) of the skin, the intensity of which is directly proportional to the clinical efficacy of the formulation. Assessment of the degree of blanching produced is therefore of use in determining the rate and extent of corticosteroid release' from the semi-solid base through the stratum corneum. Since it is the degree of blanching which is measured, we prefer to call this test the human skin blanching assay. Some of the main advantages of this assay technique are that normal healthy skin is used therefore persons with dermatological complaints are not compromised, it is not painful for the volunteers, it is non-invasive and several formulations can be evaluated simultaneously. Most commercially available topical corticosteroid preparations have been formulated in such a way as to provide optimum release of the active ingredient from the base through the stratum corneum. Despite this fact, many practitioners often prescribe dilutions of topical corticosteroid formulations, presumably in an effort to reduce the unwanted side effects. This could be problematic; dilution with an incompatible base could destroy the delivery environment thus considerably reducing the efficacy of the formulation. The method of dilution could also play a role in the suitability of the final preparation. The objective of this work was to determine the effects of two different dilutions of fluocinolone ointment at both ambient and elevated temperature on the blanching produced by the dilutions and, by inference, the relative clinical efficacies of these dilutions compared to the full strength product.
- Full Text:
- Date Issued: 1995
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