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Comfortably numb: Crump unveiled—a review of the 2011 Alan Crump retrospective exhibitio

- Cooper, Paul S

Authors: Cooper, Paul S
Date: 2011
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/147924 , vital:38685 , DOI:10.1080/00043389.2011.11877152
Description: Writing can at times be difficult. It is not without considerable anxiety that I undertake to write this particular review. Perhaps I should offer a short qualifier: this is not strictly a review but rather a collection of ideas around the works and their arrangement, as well as my own musings and reflections on Crump. I want to pick up on what I identify to be an approach that personalises Crump as a professor, colleague and artist (we find this tone embedded throughout the accompanying exhibition catalogue). 1 I have chosen to structure this essay using a series of trigger headings, some provocative and possibly even inflammatory, others more neutral and concerned with getting to the core of what this retrospective and posthumous show is all about. All the while my thinking is to channel a sense (or lack thereof, as it may turn out) of my own experience of his work and person.
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Date Issued: 2011

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Factors influencing the shape of CW-OSL signal obtained by stimulation of very deep traps in carbon-doped aluminium oxide: an experimental study

- Nyirenda, Angel N, Chithambo, Makaiko L

Authors: Nyirenda, Angel N , Chithambo, Makaiko L
Date: 2017
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/115493 , vital:34149 , https://doi.org/10.1016/j.jlumin.2017.07.016
Description: The optically stimulated luminescence from carbon-doped aluminium oxide (α-Al2O3:C) displays a peak with time under certain measurement conditions. In this paper, we present factors that influence the peak-like shape of continuous-wave optically stimulated luminescence (CW-OSL) signal. The report is based on the experimental study of OSL signals obtained by stimulation of very deep traps in α-Al2O3:C. Methods exploiting post-irradiation annealing, variable dose and temperature dependent OSL measurements were used in the investigation. It is found that the rising part of the CW-OSL peak is obtained when the rate of retrapping at the most optically active trap (main trap) exceeds the rate of direct radiative recombination following optical release of charges from all optically active traps. This is possible if, during optical stimulation, the primary trap responsible for OSL i.e. the main trap, is substantially unoccupied and the very deep, donor traps are substantially filled up. The rate of charge retrapping itself is deduced to depend on the occupancy of the acceptor traps i.e. shallow, main and secondary traps; concentration of charge carriers in the very deep, donor traps; the post-irradiation annealing temperature and the temperature at which the OSL is measured.
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Date Issued: 2017

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Pseudopolydora species associated with mollusc shells on the south coast of South Africa, with the description of Ps. dayii, sp nov

- Simon, Carol A

Authors: Simon, Carol A
Date: 2009
Language: English
Type: text , Article
Identifier: vital:6875 , http://hdl.handle.net/10962/d1011623
Description: Two species of the genus Pseudopolydora, Ps. dayii, sp. nov. and Ps. antennata, were associated with gastropods on the south and south-east coasts of South Africa. Pseudopolydora dayii is characterized by prominent post-chaetal notopodial lobes on chaetiger 1 with very long chaetae, a prominent occipital tentacle, having hooded hooks that start on chaetiger 9, branchiae that start on chaetiger 6, stout hooks and lobes placed latero-posteriorly to the hooded hooks in posterior chaetigers. It is a surface-fouler and was found on several species of wild gastropods at four of the five sites sampled and from additional material from the south-west coast and on cultured abalone (Haliotis midae) at a farm on the south-west coast. Three individuals of Ps. antennata were found only with oysters at the easternmost site. This was the first record of this species outside of the Western Cape Province and it is possible that their association with the oysters was fortuitous.
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Date Issued: 2009

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Structural and optical properties of alloyed quaternary CdSeTeS core and CdSeTeS/ZnS core–shell quantum dots

- Adegoke, Oluwasesan, Nyokong, Tebello, Forbes, Patricia B C

Authors: Adegoke, Oluwasesan , Nyokong, Tebello , Forbes, Patricia B C
Date: 2015
Language: English
Type: Article
Identifier: vital:7244 , http://hdl.handle.net/10962/d1020248
Description: Synthesis of fluorescent alloyed quantum dots (QDs) with unique optical properties suitable for a wide array of chemical, physical and biological applications is of research interest. In this work, highly luminescent and photostable alloyed quaternary CdSeTeS core QDs of two different sizes were fabricated via the organometallic hot-injection synthetic route. Characterization of the nanocrystals were performed using TEM, XRD, UV/vis and fluorescence spectrophotometric techniques. We have demonstrated in this work that the well fabricated alloyed quaternary CdSeTeS core QDs possess unique optical properties that are advantageous over conventional core/shell systems. Formation of the CdSeTeS/ZnS core/shell with the desired optical properties comes with a number of challenges, hence the advantages of the quaternary alloyed core over the core/shell QDs are (i) avoidance of the challenging process of determining the proper shell thickness which can provide the desired optical properties in the core/shell system and (ii) avoidance of the lattice-induced mismatch between the core and the shell material which can either lead to incomplete exciton confinement or dislocation at the core/shell interface. , Original publication is available at http://dx.doi.org/10.1016/j.jallcom.2015.05.083
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Date Issued: 2015

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Addressing local level food insecurity amongst small-holder communities in transition

- Shackleton, Charlie M, Hamer, Nicholas G, Swallow, Brent M, Ncube, K

Authors: Shackleton, Charlie M , Hamer, Nicholas G , Swallow, Brent M , Ncube, K
Date: 2015
Subjects: Food security -- South Africa Economic development -- South Africa Rural development -- South Africa
Language: English
Type: text
Identifier: http://hdl.handle.net/10962/50090 , vital:25958
Description: Food insecurity affects as significant proportion of the world's population and hence it typically receives priority attention in global policies associated with poverty, equity and sustainable development. For example, it is the first of the Millennium Development Goals and the second of their successor, the Sustainable Development Goals. Access to sufficient and nutritious food is deemed a basic human right. The latest FAO analysis of the “State of Food Insecurity in the World 2014” reports that 805 million people (approximately 11-12% of the world's population) are chronically undernourished (i.e. do not have sufficient energy intake over a period of at least one year). In sub-Saharan Africa the prevalence remains stubbornly high at 24%, the highest in the world. Whilst most interpret food insecurity to mean an insufficient quantity of food (as measured by the number of calories consumed), the widely accepted FAO definition considers four dimensions of food security, namely quantity, quality or diversity, access and use. Provision of enough calories on a daily basis is not sufficient if the diet lacks diversity and appropriate balance to provide the full range of minerals and vitamins necessary for proper health, or if the food available is culturally unacceptable. Thus, there is a pressing need for more nuanced analyses of food security against all four of the dimensions embedded in the concept. Additionally, it is important that these be measured at more local or regional levels because national statistics can mask alarming regional discrepancies in food security, or amongst particular sectors of society, such as recent migrants, refugees, female- or child-headed households, those vulnerable to HIV/AIDS or the landless, to mention just a few. For example, at a national level South Africa is considered a food secure nation with respect to staple requirements, and access to sufficient food is enshrined in the Constitution (Section 27, subsection 1b), but nationally one in twenty (i.e. approx. 2.5 million people) go to bed hungry most nights, and 23% of children below the age of 15 are physically stunted, severely stunted or wasted, due to the long-term ill effects of insufficient food or of inadequate diversity and quality. At a subnational level, there are marked differences between rural and urban populations and even between geographic areas (for example, the prevalence of stunting amongst boys less than 15 years old is 23% in the Eastern Cape, compared to 12% in Gauteng). Once again, despite being a food secure nation, nationally 40% of the population have a dietary diversity score of four or less, which is a cut-off point signifying poor dietary diversity which makes people more vulnerable to malnutrition and ill health, and in Limpopo and Northwest provinces it is as high as 66% and 61%, respectively.
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Date Issued: 2015

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Mistake, financial institutions, and the contract of suretyship: Prins v ABSA Bank Ltd 1998 (3) SA 904 (C)

- Glover, Graham B

Authors: Glover, Graham B
Date: 1999
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/155985 , vital:39938 , https://heinonline.org/HOL/Page?collection=journalsamp;handle=hein.journals/tyromhldre62amp;id=488amp;men_tab=srchresults
Description: Although the debate about contractual mistake and its theoretical foundations has evolved to the point where disagreement and contradiction has in recent times been replaced by a far higher degree of certainty and clarity (Van der Merwe and Van Huyssteen "Reasonable reliance on consensus, iustus error and the creation of contractual obligations" 1994 SALJ 679 686; Hutchison "Contract formation" in Zimmermann and Visser (eds) Southern Cross: Civil law and common law in South Africa (1996) 193), judgments dealing with the question of mistake will no doubt continue to provide interesting insights into this area of the law. Prins v ABSA Bank Ltd serves as a case in point.
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Date Issued: 1999

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Elucidation of the complex Baylis-Hillman reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone

- Idahosa, Kenudi C, Molefe, Duduzile M, Pakade, Vusumzi E, Brown, Michael E

Authors: Idahosa, Kenudi C , Molefe, Duduzile M , Pakade, Vusumzi E , Brown, Michael E
Date: 2011
Language: English
Type: Article
Identifier: vital:6574 , http://hdl.handle.net/10962/d1004137
Description: DABCO-catalyzed reaction of 3-methoxy-2-nitrobenzaldehyde with methyl vinyl ketone (MVK) affords a mixture of products, comprising the ‘normal’ Baylis-Hillman adduct, theMVKdimer and a pair of diastereomeric bis-(MVK)Baylis-Hillman adducts. 1HNMRspectroscopy-based kinetic studies have provided clear insights into the competing pathways and product distribution in this complex reaction.
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Date Issued: 2011

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The abundance of an invasive freshwater snail Tarebia granifera (Lamarck, 1822) in the Nseleni River, South Africa

- Jones, Roy W, Hill, Jaclyn M, Coetzee, Julie A, Hill, Martin P, Avery, T S, Weyl, Olaf L F

Authors: Jones, Roy W , Hill, Jaclyn M , Coetzee, Julie A , Hill, Martin P , Avery, T S , Weyl, Olaf L F
Date: 2017
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/69077 , vital:29382 , https://doi.org/10.2989/16085914.2017.1298984
Description: The invasive freshwater snail Tarebia granifera (Lamarck, 1822) was first reported in South Africa in 1999 and it has become widespread across the country, with some evidence to suggest that it reduces benthic macroinvertebrate biodiversity. The current study aimed to identify the primary abiotic drivers behind abundance patterns of T. granifera, by comparing the current abundance of the snail in three different regions, and at three depths, of the highly modified Nseleni River in KwaZulu-Natal, South Africa. Tarebia granifera was well established throughout the Nseleni River system, with an overall preference for shallow waters and seasonal temporal patterns of abundance. Although it is uncertain what the ecological impacts of the snail in this system are, its high abundances suggest that it should be controlled where possible and prevented from invading other systems in the region.
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Date Issued: 2017

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Food waste generation and potential interventions at Rhodes University, South Africa

- Painter, Kathleen, Thondhlana, Gladman, Kua, Harn W

Authors: Painter, Kathleen , Thondhlana, Gladman , Kua, Harn W
Date: 2016
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/67733 , vital:29135 , https://doi.org/10.1016/j.wasman.2016.07.013
Description: Publisher version , Estimation of food waste generation represents the first step when considering efforts to reduce waste generation and monitor food waste reduction against set targets. This study reports on an estimation of food waste generated in university dining halls at Rhodes University, South Africa. Daily food waste generation was estimated at about 555 g per student or 2 tonnes across all sample dining halls, translating to about 450 tonnes per year. The results show that food waste is influenced by an array of contextual factors, including distance to dining hall, gender composition of hall and meal times and meal options. It is estimated that the university could save up to US$ 80 000 annually for every 10% reduction in the current rate of food waste generation. Possible educational, technical and administrative interventions for food waste reduction are discussed.
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Date Issued: 2016

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Congruence between fine-scale genetic breaks and dispersal potential in an estuarine seaweed across multiple transition zones:

- Nicastro, Katy R, Assis, Jorge, Serrão, Ester A, Pearson, Gareth A, Neiva, Joao, Valero, Myriam, Jacinto, Rita, Zardi, Gerardo I

Authors: Nicastro, Katy R , Assis, Jorge , Serrão, Ester A , Pearson, Gareth A , Neiva, Joao , Valero, Myriam , Jacinto, Rita , Zardi, Gerardo I
Date: 2020
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/149873 , vital:38908 , https://0-doi.org.wam.seals.ac.za/10.1093/icesjms/fsz179
Description: Genetic structure in biogeographical transition zones can be shaped by several factors including limited dispersal across barriers, admixture following secondary contact, differential selection, and mating incompatibility. A striking example is found in Northwest France and Northwest Spain, where the estuarine seaweed Fucus ceranoides L. exhibits sharp, regional genetic clustering. This pattern has been related to historical population fragmentation and divergence into distinct glacial refugia, followed by post-glacial expansion and secondary contact. The contemporary persistence of sharp ancient genetic breaks between nearby estuaries has been attributed to prior colonization effects (density barriers) but the effect of oceanographic barriers has not been tested. Here, through a combination of mesoscale sampling (15 consecutive populations) and population genetic data (mtIGS) in NW France, we define regional genetic disjunctions similar to those described in NW Iberia. Most importantly, using high resolution dispersal simulations for Brittany and Iberian populations, we provide evidence for a central role of contemporary hydrodynamics in maintaining genetic breaks across these two major biogeographic transition zones. Our findings further show the importance of a comprehensive understanding of oceanographic regimes in hydrodynamically complex coastal regions to explain the maintenance of sharp genetic breaks along continuously populated coastlines.
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Date Issued: 2020

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Thermoluminescence of α-Al2O3: C, Mg annealed at 1200° C

- Kalita, Jitumani M, Chithambo, Makaiko L

Authors: Kalita, Jitumani M , Chithambo, Makaiko L
Date: 2018
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/111030 , vital:33365 , https://doi.org/10.1016/j.nimb.2018.03.003
Description: Stimulated luminescence in α-Al2O3:C,Mg has thus far been studied for samples annealed at temperature no higher than 900 °C as can be seen by an examination of the literature. We report the thermoluminescence (TL) features of α-Al2O3:C,Mg annealed at 1200 °C. A glow curve measured at 1 °C/s from the samples annealed at 1200 °C shows eight peaks at 54, 80, 102, 173, 238, 290, 330 and 387 °C. Kinetic analyses show that the peak at 54 °C follows general order kinetics (b = 1.3) whereas the rest follow first order kinetics. The values of the activation energy of the peaks are between 0.77 eV and 1.90 eV and the frequency factors are of the order of 1010–1014 s−1. The intensity of the peaks at 54, 80, 102 and 173 °C increase with heating rate whereas those of the peaks at 238 and 290 °C decrease with heating rate. The decrease of intensity of the peaks at 238 and 290 °C with heating rate is due to thermal quenching whereas the increase of intensity of the peaks with heating rate indicates an inverse thermal-quenching-like behaviour. Interestingly this behaviour is observed only after annealing at 1200 °C. The activation energy for thermal quenching as calculated using the peaks at 238 and 290 °C are (1.02 ± 0.16) eV and (1.33 ± 0.15) eV respectively. Regarding the dosimetric features, the dose response of the peaks at 54, 80 and 102 °C are sublinear within 1–10 Gy and the peak at 54 °C saturates above 6 Gy. In contrast, the response of the peak at 173 °C is sublinear with 1–4 Gy and superlinear between 4 and 10 Gy. The peaks are found to fade at different rates and the rate of fading is also affected by annealing.
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Date Issued: 2018

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Adult binge drinking: rate, frequency and intensity in Buffalo City Metropolitan Municipality, South Africa

- Owolabi, Eyitayo Omolara, Goona, Daniel Ter, Adeniyi, Oladele Vincent, Seekoea, Eunice

Authors: Owolabi, Eyitayo Omolara , Goona, Daniel Ter , Adeniyi, Oladele Vincent , Seekoea, Eunice
Date: 2018
Language: English
Type: text , article
Identifier: http://hdl.handle.net/11260/4944 , vital:44305 , https://doi.org/10.1080/20786190.2017.1382970
Description: This study was conducted to explore views about the execution of powers and functions of the police in the light of related challenges. This study made use of data from a total of 83 adult participants (a survey involving 73 individuals, and 10 in-depth interviews), including males and females of diverse occupational backgrounds from Bindura and Mount Darwin policing districts in Zimbabwe. A closed-ended, mostly Likert-scale-based questionnaire was used to collect data about the prevalent forms of police abuse of powers and functions, while an in-depth interview guide was provided to harvest information qualitatively. Findings reveal that police officers abuse their powers through unlawful arrests, arbitrary search and seizure, excessive use of force, unlawful methods of investigation, and ill treatment of detainees. Though not as prevalent as other forms of abuse, malicious criminal prosecution and partisan policing were also cited.K EYWOR DS: powers, abuse, function, police, Zimbabwe
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Date Issued: 2018

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Spectral study of radioluminescence in carbon-doped aluminium oxide

- Nyirenda, Angel N, Chithambo, Makaiko L

Authors: Nyirenda, Angel N , Chithambo, Makaiko L
Date: 2018
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/110067 , vital:33220 , https://doi.org/10.1016/j.radmeas.2018.06.026
Description: The spectral emission study of the radioluminescence (RL) measured from carbon-doped aluminium oxide (α-Al2O3:C) at various temperatures between 30 and 300∘C is reported. The energy-resolved RL emission spectra measured at room temperature show seven gaussian emission bands centred at 1.75, 1.79, 1.85, 2.22, 2.96, 3.72 and 4.44 eV. The 2.96-eV emission, associated with F-centres, is the primary RL emission whereas the narrow (R-line) emission centred at 1.79 eV, associated with Cr3+ impurity ions, is the most intense secondary emission. However, the intensity of 1.79-eV emission decreases with repeated RL measurements. The central emission energy for F-centres is constant throughout the temperature range of investigation. The full width at half maximum (FWHM) for the F-centre emission band increases with temperature whereas the F-centre peak intensity exhibits thermal quenching behaviour at temperatures above 160∘C. On the other hand, the emission energy for the R-line emission of Cr3+ is constant for temperatures between 30 and 160∘C, whereas its peak intensity generally decreases with temperature. F-centres experience strong-coupling in their crystallographic sites with estimated electron-lattice coupling parameters of S = 5.0 ± 0.9, Ep = 0.079 ± 0.008 eV and ν = 1.91 × 1013 Hz where S, Ep and ν are the Huang-Rhys factor, the phonon energy and the phonon frequency, respectively. The RL spectra recorded while ramping the temperature of a sample at a constant rate have been compared against conventional TL spectra.
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Date Issued: 2018

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On the sensitivity of thermally and optically stimulated luminescence of α-Al2O3: C and α-Al2O3: C, Mg

- Kalita, Jitumani M, Chithambo, Makaiko L

Authors: Kalita, Jitumani M , Chithambo, Makaiko L
Date: 2017
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/119803 , vital:34784 , https://doi.org/10.1016/j.radmeas.2017.03.006
Description: The luminescence sensitivity of α-Al2O3:C and α-Al2O3:C, Mg is of interest because of the contemporary use of these materials in dosimetry related applications. We report investigations concerning the change in sensitivity of thermoluminescence (TL) and optically stimulated luminescence (OSL) from α-Al2O3:C and α-Al2O3:C, Mg with re-use. The study was carried out on a set of un-annealed samples and others annealed at 700 and 900 °C. The TL and OSL sensitivity in α-Al2O3:C and α-Al2O3:C, Mg was found to increase with sample re-use whether the intensity was monitored as peak area or peak height for the main TL peak or, in the case of OSL, as the maximum intensity or the area under a decay curve. The fractional increase in area under either the main TL peak or the OSL decay curve exceeds that of the TL peak height or maximum OSL intensity when samples are re-used. However, when un-annealed samples are used, any increase in TL peak height or peak area per measurement is less than observed in annealed samples. It is also interesting to note that the change in maximum OSL intensity or OSL area is minimal for samples annealed at 900 °C. In general, the TL sensitivity in α-Al2O3:C increases more than that in α-Al2O3:C, Mg with re-use. On the other hand, the OSL sensitivity in α-Al2O3:C, Mg increases more than that in α-Al2O3:C with re-use. These findings suggest that it is advisable to take into account the fractional increase in sensitivity per measurement when one uses α-Al2O3:C as a TL dosimeter and α-Al2O3:C, Mg as an OSL dosimeter.
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Date Issued: 2017

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Deriving an optimal threshold of waist circumference for detecting cardiometabolic risk in sub-Saharan Africa

- Longo–Mbenza, Benjamin, K Ekoru, GAV Murphy, EH Young, H Delisle, CS Jerome , F Assah, JPD Nzambi, JBK On'Kin , F Buntix, MC Muyer, DL Christensen, CS Wesseh, A Sabir, C Okafor, ID Gezawa, F Puepet, O Enang, T Raimi, E Ohwovoriole, OO Oladapo, P Bovet, W Mollentze, N Unwin, WK Gray, R Walker K Agoudavi, S Siziya, J Chifamba, M Njelekela, CM Fourie, S Kruger, AE Schutte, C Walsh, D Gareta, A Kamali, J Seeley, SA Norris NJ Crowther, D Pillay, P Kaleebu, AA Motala and MS Sandhu on behalf of the African Partnership for Chronic Disease Research (APCDR)

Authors: Longo–Mbenza, Benjamin , K Ekoru, GAV Murphy, EH Young, H Delisle, CS Jerome , F Assah, JPD Nzambi, JBK On'Kin , F Buntix, MC Muyer, DL Christensen, CS Wesseh, A Sabir, C Okafor, ID Gezawa, F Puepet, O Enang, T Raimi, E Ohwovoriole, OO Oladapo, P Bovet, W Mollentze, N Unwin, WK Gray, R Walker K Agoudavi, S Siziya, J Chifamba, M Njelekela, CM Fourie, S Kruger, AE Schutte, C Walsh, D Gareta, A Kamali, J Seeley, SA Norris NJ Crowther, D Pillay, P Kaleebu, AA Motala and MS Sandhu on behalf of the African Partnership for Chronic Disease Research (APCDR)
Date: 2018
Language: English
Type: text , article
Identifier: http://hdl.handle.net/11260/5389 , vital:44560 , https://www.nature.com/articles/ijo2017240
Description: BACKGROUND: Waist circumference (WC) thresholds derived from western populations continue to be used in sub-Saharan Africa (SSA) despite increasing evidence of ethnic variation in the association between adiposity and cardiometabolic disease and availability of data from African populations. We aimed to derive a SSA-specific optimal WC cut-point for identifying individuals at increased cardiometabolic risk. METHODS: We used individual level cross-sectional data on 24 181 participants aged ⩾15 years from 17 studies conducted between 1990 and 2014 in eight countries in SSA. Receiver operating characteristic curves were used to derive optimal WC cutpoints for detecting the presence of at least two components of metabolic syndrome (MS), excluding WC. RESULTS: The optimal WC cut-point was 81.2 cm (95% CI 78.5–83.8 cm) and 81.0 cm (95% CI 79.2–82.8 cm) for men and women, respectively, with comparable accuracy in men and women. Sensitivity was higher in women (64%, 95% CI 63–65) than in men (53%, 95% CI 51–55), and increased with the prevalence of obesity. Having WC above the derived cut-point was associated with a twofold probability of having at least two components of MS (age-adjusted odds ratio 2.6, 95% CI 2.4–2.9, for men and 2.2, 95% CI 2.0–2.3, for women). CONCLUSION: The optimal WC cut-point for identifying men at increased cardiometabolic risk is lower (⩾81.2 cm) than current guidelines (⩾94.0 cm) recommend, and similar to that in women in SSA. Prospective studies are needed to confirm these cut-points based on cardiometabolic outcomes.
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Date Issued: 2018

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Reduction in transport in wheat (Triticum aestivum) is caused by sustained phloem feeding by the Russian wheat aphid (Diuraphis noxia)

- Botha, Christiaan E J, Matsiliza, Babalwa

Authors: Botha, Christiaan E J , Matsiliza, Babalwa
Date: 2004
Language: English
Type: Article
Identifier: vital:6498 , http://hdl.handle.net/10962/d1004498
Description: The Russian wheat aphid (Diuraphis noxia) feeds preferentially from the phloem of longitudinal veins of nonresistant wheat leaves. The xenobiotic, 5,6-CFDA was applied to exposed leaf blade mesophyll cells in control and aphid-infested plants. In control plants, the fluorophore moved approximately 5–6cm from the point of application of 5,6-CFDA within 3h of application. The fluorochrome was transported in the sieve tube companion cell complex, including those in the numerous interconnecting transverse veins. Leaf blades on which the Russian wheat aphid had been feeding demonstrated a marked decrease in 5,6-CF transport. Aphids feeding on the leaves formed local sinks and redirected the fluorophore (and presumably associated assimilate) to the aphids’ gut, with little longitudinal translocation of 5,6-CF below inserted stylets or aphid feeding areas. Aniline blue staining revealed massive deposits of wound and reaction callose caused by the aphids, with callose associated with the sieve plates, pore-plasmodesma between the companion cells and their associated sieve tubes, as well as with plasmodesmal aggregates in parenchymatous elements within the vascular bundles. Leaves that had been colonised by aphids but from which the aphids were removed, showed extensive wound callose deposits, which persisted for up to 48h after removal of aphid colonies, suggesting that the damage caused by aphid feeding is a long-term, non-transient event in non-resistant plants.
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Date Issued: 2004

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