SUNScholar - Browsing by Author "Archer, E."

Browsing by Author "Archer, E."

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Arbuscular mycorrhizal colonisation modifies the water relations of young transplanted grapevines (vitis)
(South African Society for Enology and Viticulture, 2004) Van Rooyen, M.; Valentine, A.; Archer, E.
The effect of arbuscular mycorrhizal (AM) colonisation on the alleviation of transplantation shock in young grapevines was investigated. One-year-old grapevines (Sauvignon blanc on Richter 99), colonised with Glomus etunicatum (Becker and Gerdemann), were cultivated in an atmosphere-controlled tunnel. Water relations, leaf photosynthetic parameters and growth characters were evaluated. AM colonisation enhanced the photosynthetic performance of host plants, but had no influence on biomass and mineral nutrition of the transplanted hosts. The increased photosynthetic rates of the AM plants were related to improved water relations. Stomata] conductance, transpiration rate and midday xylem water potential were higher in the AM hosts during the transplanted period. These results indicate that AM inoculation can influence the water relations of transplanted grapevine rootstocks, thereby improving photosynthetic performance and potential survival during the initial growth stages of the host plants.
The development, implementation and evaluation of a short course in objective structured clinical examination (OSCE) skills
(Medical & Pharmaceutical Publications (Pty) Ltd -- MedPharm Publications, 2012-02) De Villiers, A.; Archer, E.
Background: Objective structured clinical examination (OSCE) examiner training is widely employed to address some of the reliability and validity issues that accompany the use of this assessment tool. An OSCE skills course was developed and implemented at the Stellenbosch Faculty of Health Sciences and its influence on participants (clinicians) evaluated. Method: Participants attended the OSCE skills course, which included theoretical sessions concerning topics such as standard setting, examiner influence and assessment instruments, as well as two staged OSCEs, one at the beginning and the other at the end of the course. During the latter, each participant examined a student role-player performing a technical skill while being video recorded. Participants’ behaviour and assessment results from the two OSCEs were evaluated, as well as the feedback from participants regarding the course and group interviews with student role players. Results: There was a significant improvement in inter-rater reliability as well as a slight decrease in inappropriate examiner behaviour, such as teaching and prompting during assessment of students. Furthermore, overall feedback from participants and perceptions of student role players was positive. Conclusions: In this study, examiner conduct and inter-rater reliability was positively influenced by the following interventions: examiner briefing, involvement of examiners in constructing assessment instruments, as well as examiners viewing (on DVD) and reflecting on their assessment behaviour. This study proposes that the development and implementation of an OSCE skills course is a worthwhile endeavour in improving validity and reliability of the OSCE as an assessment tool.
Effect of growth arrestment disease on the anatomy and ultrastructure of vitis vinifera L. var. sultana
(South African Society for Enology and Viticulture, 1981) De la Harpe, A. C.; Archer, E.
The anatomical and ultrastructural changes caused by the so called Growth Arrestment Disease (G.A.D.) in Vitis vinifera L. var. sultana were investigated by means of scanning and transmitted electron microscopy as well as light microscopy. Important morphological symptoms are described. Anatomical abnormalities were found, especially in the leaves and Hower clusters of the affected vines. Heat and moisture stress may induce abnormal physiological changes, and this may give rise to G.A.D.-symptoms.
The effect of plant spacing on the water status of soil and grapevines
(South African Society for Enology and Viticulture, 1989) Archer, E.; Strauss, H. C.
The effect of plant spacing on soil water content and plant water status is described. The higher root densities of narrower plantings resulted in a more rapid depletion of soil water content. This resulted in a more negative leaf water potential which, in turn, resulted in earlier stomatal closure, affecting transpiration rate negatively. Consequently grapes from narrower spaced vines ripened under higher water stress conditions than those from wider spaced vines.
Effect of shading on the performance of vitis vinifera L. cv. cabernet sauvignon
(South African Society for Enology and Viticulture, 1989) Archer, E.; Strauss, H. C.
The effect of shading on the performance of Cabernet Sauvignon was studied. Significant different levels of canopy density were created using the growth of neighbouring vines, thus ensuring no artificial change in natural light composition. Light penetration in these canopies differed significantly between treatments. Berry mass, bunch mass and yield as well as skin colour were decreased with increasing levels of shading, while pH, K-concentration and TT A were increased. Tartaric acid decreased while malic acid increased with an increase in shading. Wine quality was negatively affected.
The effect of trellis systems on the performance of vitis vinifera L. cvs. sultanina and chenel in the Lower Orange River Region
(South African Society for Enology and Viticulture, 1990) Swanepoel, J. J.; Hunter, J. J.; Archer, E.
The effect of six trellis systems on the reproductive and vegetative performance of Sultanina and Chene), grown in the lower Orange River region of South Africa, was investigated. Larger trellis systems significantly increased the yield of both cultivars, and the photosynthetic activities of the leaves at veraison as well as the canopy light environment tended to be higher for these systems. The higher yields recorded for Sultanina were attributed to improved budding percentages, which were caused by improved light environments at the basal 'buds. The improved yield obtained for Chene! however, was due to higher bunch masses, which were most likely caused by the higher photosynthetic activities of the leaves.
The effect of vine spacing on some physiological aspects of vitis vinifera L. (cv. pinot noir)
(South African Society for Enology and Viticulture, 1990) Archer, E.; Strauss, H. C.
The effect of vine spacing on leaf temperature, radiant energy, some canopy characteristics, leaf-water potential, stomata! conductance, the rate of transpiration and the rate of photosynthesis was measured and discussed. With more closely spaced vines, canopies were less dense than with more widely spaced vines mainly because of less vigorous shoot growth. The consequent better sunlight penetration favoured the physiology of more closely spaced vines early in the season. During the latter part of the season the situation was reversed and the physiology of more widely spaced vines was favoured mainly because of better water supply.
The effect of vine spacing on the vegetative and reproductive performance of vitis vinifera L. ( cv. Pinot noir)
(South African Society for Enology and Viticulture, 1991) Archer, E.; Strauss, H. C.
Data concerning growth, yield, grape composition and wine quality are presented for five years. Closer spacing reduced cane mass and yield per vine but increased them per hectare. Less dense canopies as well as a larger leaf area: fruit mass ratio with more closely spaced vines au~mented grafe and wine quality. Given the specific circumstances of this trial, a vine spacing resulting in between 1,0 m and 2,0 m soil surface per vine proved to be optimum for Pinot noir.
Interrogating patient-centredness in undergraduate medical education using an integrated behaviour model
(Taylor & Francis Group, 2017) Archer, E.; Bitzer, E.; Van Heerden, B. B.
Background: Patient-centredness, an approach that puts the patient at the centre of the consultation, thus focusing on patients instead of on his/her diseases, has been identified by most medical schools as a desired core competence of their graduates. Despite some curriculum initiatives, medical students often display a lack of patient-centredness upon graduation. This bears reason for concern and it was thus deemed important to explore possible factors that influence the teaching and learning of patient-centredness in an undergraduate medical curriculum. The article suggests a framework that can assist programme developers to conceptualise the teaching and learning of patient-centredness across an undergraduate curriculum. Methods: A qualitative exploratory case study design was used for the study with final-year medical students. Themes of meaning were deduced from the data by employing components of an Integrated Behavior Model (IBM) of Fishbein. Results: The findings of the study revealed that seven factors play a role: background characteristics of students, attitudinal factors, subjective norms (the hidden curriculum), student self-efficacy, acquired skills and knowledge, the environment or context within which patient-centredness is taught and learnt, as well as assessment of learning. Conclusions: Patient-centredness is a complex construct and authors often write about only one of its components. This paper attempts to consider the total undergraduate medical curriculum students are exposed to when they learn about being patient-centred. The teaching and learning of such a multidimensional construct require a comprehensive approach in order to be effective and the IBM seems to be a useful and applicable theoretical model to apply.
Interventions aimed towards the development of patient-centredness in undergraduate medical curricula : a scoping review
(Health and Medical Publishing Group, 2018) Archer, E.; Meyer, I.
Background. Patient-centredness has been identified by most medical schools worldwide as a desired core graduate competence. Patient-centredness positions the patient at the centre of the consultation and, therefore, focuses on the patient instead of on the disease. The concept of patient-centredness is, however, multifaceted. The choice and development of approaches and interventions that can enhance or sustain the various dimensions of patient-centredness are challenges for undergraduate medical curriculum developers. Objectives. To determine what the extent and nature of published scientific literature on implemented interventions are and how these could assist in fostering the various constructs of patient-centredness in undergraduate medical curricula. Furthermore, to determine which of these interventions could potentially be applied and incorporated in the context of the undergraduate medical curriculum at the Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa. Methods. The study followed the 6-step scoping review methodology framework. Four electronic databases were searched. Two independent reviewers screened citations for inclusion and performed the data abstraction. Results. Articles (N=581) were eligible for inclusion in this study. Information captured in the Excel spreadsheets resulted in 9 categories of teaching interventions, which could lead to the various constructs of patient-centredness. These included didactic sessions and workshops, simulated patients, reflection, small-group discussions, e-learning, peer role-play/drama/surrogate, narratives/storytelling/art, clinical experiences and mindfulness training. Conclusions. It is important to acknowledge that the development of patient-centredness in medical students is more than just a set of communication skills. Curricula need to provide learning opportunities for students to enhance knowledge, skills and attitudes related to patient-centredness to develop it as a strong competence. Furthermore, students need to be placed in clinical learning environments that foster a patient-centred approach, providing various opportunities where they can reflect on their learning, be more mindful of the needs of their patients and build caring relationships with them.
Making use of an existing questionnaire to measure patient-centred attitudes in undergraduate medical students : a case study
(Health & Medical Publishing Group, 2014-09) Archer, E.; Bezuidenhout, J.; Kidd, M.; Van Heerden, B. B.
Background. Patient-centred care is widely acknowledged as important to achieve improved patient outcomes in healthcare. Therefore, it is vital that medical schools should foster this attitude in their students. Studies report that students are becoming less patient-centred in the period between entry to medical school and graduation. Objective. To determine the shift in attitude towards patient-centredness in a group of South African undergraduate medical students. Simultaneously, the reliability and validity of the Patient-Practitioner Orientation Scale (PPOS) in our context were measured. Methods. A cross-sectional survey was undertaken by asking all the medical students from year 1 to year 6 to complete the PPOS. The mean PPOS score for each cohort was calculated using SPSS for Windows. Reliability and validity testing was conducted using Cronbach’s alpha and confirmatory and exploratory factor analysis. Results. The average return rate across the 6 years of study was 81%. The results indicated low initial scores on the PPOS and a decrease in scores over the years of study, with the most dramatic drop being from year 1 to year 2. The PPOS showed poor validity and reliability in our context. Conclusion. The study appears to indicate the same decrease in patient-centredness in our students as has been shown in other studies using this tool. However, the low reliability and validity of the PPOS in our environment means that the result should be interpreted with caution. Factors such as our medical students’ not having had first-hand experience of the doctor-patient relationship and second-language issues may play a role. It is recommended that the PPOS not be used in our context without further exploration of the factors contributing to this loss of reliability and validity.
The occurrence and infectivity of arbuscular mycorrhizal fungi in inoculated and uninoculated rhizosphere soils of two-year-old commercial grapevines
(South African Society for Enology and Viticulture, 2005) Meyer, A. H.; Botha, A.; Valentine, A. J.; Archer, E.; Louw, P. J. E.
Arbuscular mycorrhizal (AM) fungal populations present in the rhizosphere of vine roots in the vineyards of a commercial farm in the Stellenbosch Region were investigated using microscopic analyses. AM root colonisation levels of between 70% and 90% were found in both grapevine roots that were previously artificially inoculated with commercial AM inocula, and in uninoculated (control) grapevine roots. The AM fungal isolates in the rhizosphere soil, identified using morphological criteria, belonged to the genera Acaulospora, Gigaspora, Glomus, Sclerocystis and Scutellospora. The majority of species found was not present in the commercial inocula and was either indigenous to the vineyard or originated from the nursery where the vines were obtained. Isolates of Glomus and Acaulospora appeared to be the most abundant. The AM fungal species occurred at a soil phosphorus (P) concentration of up to 80 mg/kg P and a soil pH (KCl) that ranged between 5.63 and 6.10. Total spore counts ranged between 1 000 and 3 779 spores/100 g dry soil. In accordance with literature, lower spore concentrations were recorded for the heavier soil types with no cover crop system, compared with the sandy soil type on which cover crops were sown annually.
Qualitative and quantitative detection of SARS-CoV-2 RNA in untreated wastewater in Western Cape Province, South Africa
(Health & Medical Publishing Group, 2021-01-28) Johnson, R.; Muller, C. J. F.; Ghoor, S.; Louw, J.; Archer, E.; Surujlal-Naicker, S.; Berkowitz, N.; Volschenk, M.; Brocker, L. H. L.; Wolfaardt, G.; Van der Walt, M.; Mutshembele, A. M.; Malema, S.; Gelderblom, H. C.; Muhdluli, M.; Gray, G.; Mathee, A.; Street, R.
ENGLISH ABSTRACT: Recent studies have shown that the detection of SARS-CoV-2 genetic material in wastewater may provide the basis for a surveillance system to track the environmental dissemination of this virus in communities. An effective wastewater-based epidemiology (WBE) system may prove critical in South Africa (SA), where health systems infrastructure, testing capacity, personal protective equipment and human resource capacity are constrained. In this proof-of-concept study, we investigated the potential of SARS-CoV-2 RNA surveillance in untreated wastewater as the basis for a system to monitor COVID-19 prevalence in the population, an early warning system for increased transmission, and a monitoring system to assess the effectiveness of interventions. The laboratory confirmed the presence (qualitative analysis) and determined the RNA copy number of SARS-CoV-2 viral RNA by reverse transcription polymerase chain reaction (quantitative) analysis from 24-hour composite samples collected on 18 June 2020 from five wastewater treatment plants in Western Cape Province, SA. The study has shown that a WBE system for monitoring the status and trends of COVID-19 mass infection in SA is viable, and its development and implementation may facilitate the rapid identification of hotspots for evidence-informed interventions.
Shoot heterogeneity effects on Shiraz/Richter 99 grapevines. II, Physiological activity
(SASEV, 2008) Cloete, H.; Archer, E.; Novello, V.; Hunter, J. J.
In this study, the physiology of normally developed and underdeveloped shoots is compared in an attempt to quantify the effect of shoot heterogeneity in a Shiraz/Richter 99 vineyard, located in the Stellenbosch area of the Western Cape, South Africa. Comparisons are made between normally developed and underdeveloped shoots from shaded and well-exposed canopies. In the first five weeks after véraison, photosynthetic and transpiration rates, stomatal conductance and water-use efficiency (WUE) decreased as berry ripening progressed, while the internal CO2 levels of the leaves increased. Since differences in activity between individual leaves from normally developed and underdeveloped shoots only became apparent in the third week after véraison, it seemed as if the leaf area per shoot played a more important role than the photosynthetic output per unit leaf area in determining photosynthetate supply to the rest of the vine up to this stage. From the third week after véraison, higher levels of photosynthetates were produced by normally developed shoots than by underdeveloped shoots, due to the larger effective leaf area per shoot as well as the higher photosynthetic activity per unit leaf area. This points to premature senescence of the leaves on underdeveloped shoots. The quantity and quality of the yield from normally developed shoots are expected to benefit from the higher physiological output of the leaves. The enhancing effect on leaf functioning induced by canopy exposure became apparent from the third week after véraison.
Shoot heterogeneity effects on Shiraz/Richter 99 grapevines. III, Leaf chlorophyll content
(SASEV, 2008-03) Cloete, H.; Archer, E.; Novello, V.; Hunter, J. J.
In this study, the leaf chlorophyll content of normally developed and underdeveloped shoots was compared in an attempt to quantify the effect of shoot heterogeneity in a Shiraz/Richter 99 vineyard, located in the Stellenbosch area of the Western Cape, South Africa. Comparisons are also made between normally developed and underdeveloped shoots from shaded and well-exposed canopies. No positive correlation was found between the photosynthetic activity and the chlorophyll concentration of the leaves at five weeks after véraison. Equal amounts of chlorophyll per cm2 and a non-significant difference in the assimilation rate were calculated for the leaves of normally developed and underdeveloped shoots. No significant differences were found between the shaded and well-exposed canopies. It therefore appears that it is the effective surface area per leaf or per shoot rather than the chlorophyll concentration or activity that may be responsible for any apparent difference in the photosynthetic output of the leaves from normally developed and underdeveloped shoots in shaded or well-exposed canopies.
Young grapevine response and root colonisation following inoculation with arbuscular mycorrhizal fungi
(South African Society for Enology and Viticulture, 2004) Meyer, A. H.; Valentine, A. J.; Botha, A.; Archer, E.; Louw, P. J. E.
The host plant response following inoculation with commercially available arbuscular mycorrhizal (AM) fungi was determined in young grapevines under field conditions which would prevail on a typical farm. Measurements regarding growth improvement, nutrition and water relations were made in a field trial carried out on a commercial farm in the Stellenbosch region. Merlot noir grafted onto 101-14 Mgt and 110 Richter (110 R) in a Westleigh soil form and 99 Richter (99 R) in a Fernwood soil form was planted in December 1998. Vine roots were inoculated during planting with Biocult, Vaminoc and Glomus sp. 1054. Inoculation generally had little effect on xylem sap and leaf nutrient concentrations, water relations or growth responses. This was mainly ascribed to indigenous AM fungi, which seemed to have masked the effects of inoculation. A high soil P concentration was also implicated as a possible contributing factor to the general lack of grapevine response to AM inoculation.

Browsing by Author "Archer, E."

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