3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Elemental radiography using fast neutron beams(2012-04-11) Guzek, JacekItem The use of visual representation as a teaching strategy in the physical science classroom(2012-01-19) Naidoo, GonasegranAs science teachers, one of our objectives is to find new and effective teaching strategies to represent scientific concepts in a simplified and uncomplicated way to our learners. This study seeks to examine the merits of using visualisation as a means of representing science in a less complex way for learners as they come to terms with some of the conceptual difficulties that they experience. One of the challenges this study aims to highlight is the multilingual environment that physical sciences educators must teach within where learners experience conceptual difficulties as well as learning difficulties as a result of language. This study is set against the backdrop of a typical South African township school where learners learn science in a second language. A sample of 31 learners and their science teacher participated in the research. The use of a visual representation in the form of a series of pictures representing various scenarios of objects colliding was used by the teacher to consolidate the learner’s existing knowledge of the concept of conservation of linear momentum. The results obtained from the questionnaires and interviews indicate that the majority of the learners could have benefitted from the pictures. The pictures served as a means of remediating some of the conceptual difficulties that they had experienced in relation to the vector nature of the motion of the colliding objects, in particular. The study could not conclusively ascertain whether the use of visual representation can specifically help second language learners in overcoming their learning difficulties as a result of the language of instruction. Despite this outcome, the results of the study did indicate that the learners had benefitted from the visual representations. Some of the learners had expressed that the pictures had visually brought to life the practical scenarios that they would have otherwise experienced only through the verbal and written mode of instruction. The study recommends that visualisation in science education can play a significant role in helping learners with conceptual difficulties not just as a result of the language of instruction but also as a result of the general complexities of science that are abstract to even first language learners.Item Cooling methods to treat capture-induced hyperthermia in blesbok (Damaliscus dorcas phillipsi)(2011-12-07) Sawicka, JoannaWild animals are captured for management, health, translocation and research purposes. Capture is an unnaturally stressful event, which may result in morbidity or mortality. An attributing cause of the morbidity and mortality is capture-induced hyperthermia; the larger the magnitude and the longer the duration of this captured-induced hyperthermia, the greater the likely risk to the animal. The most common practice currently used in the field to lower body temperature is to douse hyperthermic animals with water. However, the water used is often at ambient temperatures and its efficacy is not known. We investigated whether this method and alternative methods are effective at lowering the body temperature of hyperthermic animals. To achieve these aims we implanted 19 blesbok with miniature temperature-sensitive data loggers in their abdomens and into their subcutaneous layers (at the sites of the flank, groin, lower neck and upper neck). The loggers continuously recorded core body temperatures of the blesbok throughout the study period at an interval of six minutes. We successfully retrieved complete data sets from 12 blesbok. The animals were captured on six separate occasions using a technique which elicited hyperthermia. Five animals were cooled by dousing with water of different temperatures (4°C, 17°C, 28°C) and fanning after dousing with 28°C water, in random order. Seven animals were cooled by ice packs, spraying a fine mist spray, intravenous (IV) infusion of one litre of 4°C water and 28°C water-dousing. Through the use of our continuous logging of body temperature we established the normal body temperature of the blesbok, which displayed a regular 24 hour body temperature pattern. The average daily body temperature of the blesbok was 38.8°C ± 0.4°C, with a minimum body temperature of 37.9°C ± 0.1°C and a maximum body temperature of 39.4°C ± 0.1°C. The body temperature after capture was as high as 41°C-42°C, which was significantly higher than the normal body temperature (Student’s t-test, P < 0.05). The animals were cooled once they were immobilised and the start of cooling was denoted as time zero. In the control (no active cooling) intervention the body temperature decreased to only about 40°C. Dousing animals with water, irrespective of its temperature, resulted in significant cooling (P < 0.05) of the animals, as indicated by their minimum body temperature reached, change in body temperature and rate of cooling. The water-dousing interventions decreased the body temperature to about 38°C after an hour, which was significantly lower than the control (RM-ANOVA, P < 0.05) but there was no significant difference in the minimum body temperature reached between the different water temperatures or by the addition of fanning (RM-ANOVA, P > 0.05). The water-dousing interventions cooled the animals more quickly than did the control (RM-ANOVA, P < 0.05), and the coldest water (4°) cooled the animals quicker than did the 28°C water-dousing (RM-ANOVA, P < 0.05). The core body temperature minus the subcutaneous temperature was calculated, and revealed a peak difference of about 3.5°C after the 4°C water-dousing. Ice-packs also resulted in significant cooling (P < 0.05) of the animals, as depicted by their minimum body temperature reached, change in body temperature and rate of cooling. The ice-packs lowered the body temperature to a minimum of about 38°C, which was significantly lower than the control (RM-ANOVA, P < 0.05). The ice-packs also cooled the animals significantly faster than did the control, intravenous infusion and mist spray (RM-ANOVA, P < 0.05) but cooled as quickly as the 28°C water-dousing (RM-ANOVA, P > 0.05). The core body temperature minus the subcutaneous temperature for the ice-packs peaked at a difference of about 3°C. The IV infusion and mist spray were ineffective cooling methods and did not significantly (P > 0.05) alter the minimum body temperature or rate of cooling. Even though the IV infusion caused a significant reduction in body temperature by 1°C, the cooling effect from the IV infusion was short-lived because the minimum body temperature reached after the intravenous infusion and mist spray was ultimately similar to the body temperature seen in animals receiving the control (RM-ANOVA P > 0.05). Also, the intravenous infusion and mist-spray cooled as slowly as did the control (RM-ANOVA P > 0.05). Therefore, water-dousing in this study was the most effective and practical method to cool hyperthermic blesbok. Although all the water temperatures (4°C, 17°C and 28°C) that we tested were effective, the coldest water (4°C) cooled the animals quickest. The addition of fanning to the 28°C water-dousing did not increase cooling. Ice-packs were also effective but may be not as easy to use as the water-dousing method as ice-packs are large and need to be kept frozen, and therefore are cumbersome for use in the field.