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Browse selection, intake, utilisation, palatability, quality and production are tightly linked and need to be considered together in trying to improve our understanding of browsing dynamics and the interactions between browsers and vegetation. Such an understanding is necessary in order to re-evaluate determinations of browser carrying capacities and evaluating actual and potential impacts of browsing animals on vegetation composition and diversity. Browser carrying capacity is determined by both the quantity and the nutritive value of forage. The measurement of browse quantity and nutritive value and the matching of browse supply to browser demand are central to sustainable utilisation and the monitoring of vegetation health. South African savannas are poorly studied with respect to tree canopy growth and browse production making it difficult to quantify the available browse biomass on which browsing capacity estimations are based, and consequently difficult to estimate levels of browsing that are sustainable. This study addressed these issues by investigating browse dynamics, broadly aiming to (1) explore factors affecting browse production, biomass and nutritive value; (2) develop models to assess and monitor these parameters across seasons and properties; (3) use the resultant models in improving our understanding of how to determine browser carrying capacities. More specifically, our study sought to examine the effects of plant physiognomy, forage nutritive value, canopy stratum, defoliation, temperature, rainfall and soil nutrient status on the browse production of evergreen (Carissa bispinosa, Euclea divinorum, Gymnosporia senegalensis), semi-deciduous (Spirostachys africana, Ziziphus mucronata) and deciduous (Acacia nilotica, Dichrostachys cinerea) savanna tree species from June 2003 – June 2005 in three sites along the northern Zululand coastline of KwaZulu-Natal. Available browse biomass, during the dry season, of four key savanna tree species (A. nilotica, E. divinorum, G. senegalensis, and S. africana) was estimated through the development of allometric regression equations. Non-linear regression was used to investigate the relation between the leaf dry mass (LDM) and canopy volume (CVol) of each of the four tree species. Exponential regression (y = a + brlnx) of the natural logarithm of CVol data provided the most accurate and precise description of the tree CVol – LDM relation. A study was undertaken to determine which factors may influence browse production in a southern African savanna. Regression tree models for the browse production identified that the dominant factors influencing browse production were CVol (m3), season, species and height to the lowest leaves of the tree canopy (HL) (m). The length of the growing season had a marked effect on the production potential of savanna tree species, suggesting that improved conditions for growth, i.e. greater rainfall, soil moisture content and improved soil nutrient availability result in a longer period of rapid sustained growth. Species was identified as an important contributing factor to differences in browse production rates, suggesting the need for the development of species or species group models. Mean annual browse production of evergreen trees was greater than that of deciduous and semi-deciduous trees. Mean quarterly (three monthly) browse production was highest, for all trees, during the wet season, with the greatest difference between wet and dry season production being observed in deciduous forms. Evergreen forms showed continuous growth over the whole study, with enhanced growth over the wet season. Deciduous forms, on the other hand, concentrated growth in spurts, when environmental conditions became favourable, with most production occurring during a short growing season. Browse nutritive value was found to be greatest during the wet season, when growth and photosynthesis are at their greatest. Further, browse nutritive value was greatest in deciduous species. Evergreen trees were found to have greater acid detergent fibre (ADF) concentrations than both the deciduous and semi-deciduous trees. By contrast, crude protein (CP) concentrations were greater in semi-deciduous and deciduous species than in evergreen species. The daily CP requirements for maintenance for an adult impala (45 kg) were met by all species over all three study areas and all seasons. Daily CP requirements for growth and lactation, however, were only ever met by deciduous and semi-deciduous species, though this result was not consistent over study areas and seasons. Predictive models for the production of browse on deciduous, semi-deciduous and evergreen trees in northern Zululand were developed using multivariate adaptive regression spline functions. The best predictors of growing season browse production in all three tree guilds (defined here as a group of trees having a characteristic mode of living) were primarily measurable tree dimensions, while the prevailing environmental conditions had little impact. Differences in the production, nutritive value and available browse biomass between the different tree forms and seasons have a profound effect on the determination of browser carrying capacities and need to be incorporated into any game or conservation management plan. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

The way people view development is changing. The world now advocates for a development that also considers future generations. There is a paradigm shift towards sustainable development - a development in today's lifestyle without destroying the resources for tomorrow generations. Sustainable development is a broad concept that addresses how human activities impact on the economic, environmental and social well-being of an ecosystem; however, practical application of the sustainability concept is complex because its objective assessment is elusive. It is often said that the effect of technology on society has never been more profound than today. As mankind develops in science and technology to improve on his well-being, certain impacts are made on the systems that support human existence. Liquefied natural gas (LNG) technology, like gas-to-liquid (GTL) technology, is a latest innovation conceived to 'fight' the problem of gas flaring, and help contribute to the social and economic growth of the people; but it is necessary for man to know if these contemporary technologies are sustainable. This dissertation critically appraises the impact of the LNG project on the community of Bonny Island in Nigeria from a holistic perspective. The approach to the research work is three-fold: an appropriate sustainability framework is selected based on certain criteria; sustainability indicators are developed from the chosen framework; and the sustainability indicators are used to assess the impact of the project on the flora and fauna of the community. To have a clear picture of the impact of Nigeria LNG on its host community, Epe-Waterside is chosen as a control community because of its similar socio-geographical outlook to Bonny Island community. The control community is then subjected to the same set of sustainability indicators for a comparative analysis. The outcome of the research work shows that, though the economic and social conditions of Bonny Island seem much better, its environmental status remains a challenge. In other words, it can be concluded that the present approach to the operation of the LNG technology is not sustainable. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2009.

The way people view development is changing. The world now advocates for a development that also considers future generations. There is a paradigm shift towards sustainable development - a development in today's lifestyle without destroying the resources for tomorrow generations. Sustainable development is a broad concept that addresses how human activities impact on the economic, environmental and social well-being of an ecosystem; however, practical application of the sustainability concept is complex because its objective assessment is elusive. It is often said that the effect of technology on society has never been more profound than today. As mankind develops in science and technology to improve on his well-being, certain impacts are made on the systems that support human existence. Liquefied natural gas (LNG) technology, like gas-to-liquid (GTL) technology, is a latest innovation conceived to 'fight' the problem of gas flaring, and help contribute to the social and economic growth of the people; but it is necessary for man to know if these contemporary technologies are sustainable. This dissertation critically appraises the impact of the LNG project on the community of Bonny Island in Nigeria from a holistic perspective. The approach to the research work is three-fold: an appropriate sustainability framework is selected based on certain criteria; sustainability indicators are developed from the chosen framework; and the sustainability indicators are used to assess the impact of the project on the flora and fauna of the community. To have a clear picture of the impact of Nigeria LNG on its host community, Epe-Waterside is chosen as a control community because of its similar socio-geographical outlook to Bonny Island community. The control community is then subjected to the same set of sustainability indicators for a comparative analysis. The outcome of the research work shows that, though the economic and social conditions of Bonny Island seem much better, its environmental status remains a challenge. In other words, it can be concluded that the present approach to the operation of the LNG technology is not sustainable. / Thesis (M.Ing. (Development and Management))--North-West University, Potchefstroom Campus, 2009.

Thesis (MScEng) Stellenbosch University, 2014 / ENGLISH ABSTRACT: This thesis brings together productivity and risk assessments through innovative design, development and evaluation of a unique system for retrieving and analysing data. In the past, although the link between them is well-documented, these assessments have largely been dealt with as separate antagonist entities. A broad evaluation of the existing traditional and technological support systems has been conducted to identify suitable methodologies along with a common technological platform for automation. The methodologies selected for the productivity and risk assessments were; work sampling and the revised NIOSH lifting equation respectively. The automation of these procedures is facilitated through computer vision and the use of a range imaging Kinect™ camera. The standalone C++ application integrates two tracking approaches to extract real-time positional data on the worker and the work-piece. The OpenNI and OpenCV libraries are used to perform skeletal tracking and image recognition respectively. The skeletal tracker returns positional data on specific joints of the worker, while the image recognition component, a SURF implementation, is used to identify and track a specific work-piece within the capture frame. These tracking techniques are computationally expensive. In order to enable real time execution of the program, Nvidia’s CUDA toolkit and threading building blocks have been applied to reduce the processing time. The performance measurement system is a continuous sampling derivative of work sampling. The speed of the worker’s hand movements and proximity to the work-piece are used to classify the worker in one of four possible states; busy, static, idle, or out of frame. In addition to the worker based performance measures, data relating to work-pieces are also calculated. These include the number of work-pieces processed by a specific worker, along with the average and variations in the processing times. The risk assessment is an automated approach of the revised NIOSH lifting equation. The system calculates when a worker makes and/or breaks contact with the work-piece and uses the joint locations from the skeletal tracker to calculate the variables used in the determination of the multipliers and ultimately the recommended weight limit and lifting index. The final calculation indicates whether the worker is at risk of developing a musculoskeletal disorder. Additionally the information provided on each of the multipliers highlights which elements of the lifting task contribute the most to the risk. The user-interface design ensures that the system is easy to use. The interface also displays the results of the study enabling analysts to assess worker performance at any time in real time. The automated system therefore enables analysts to respond rapidly to rectify problems. The system also reduces the complexity of performing studies and it eliminates human errors. The time and costs required to perform the studies are reduced and the system can become a permanent fixture on factory floors. The development of the automated system opens the door for further development of the system to ultimately enable more detailed assessments of productivity and risk. / AFRIKAANSE OPSOMMING: Produktiwiteit en risiko evaluerings word in hierdie tesis saam hanteer deur die innoverende ontwerp, ontwikkeling en evaluering van 'n unieke stelsel vir die meting en ontleding van data. Alhoewel die skakel tussen hulle goed gedokumenteer is, word hierdie evaluering as afsonderlike antagonistiese entiteite hanteer. 'n Breë studie van die bestaande tradisionele en tegnologiese ondersteuningstelsels is gedoen om toepaslike metodes te identifiseer, om 'n gemeenskaplike tegnologiese platform vir outomatisering daar te stel. Die metodes wat gekies is vir die produktiwiteit en risiko bepalings is onderskeidelik werk monsterneming en die hersiende NIOSH opheffing vergelyking. Die outomatisering van hierdie prosedures word gefasiliteer deur middel van rekenaar visie en die gebruik van 'n Kinect™ 3D kamera. Die selfstandige C++ program integreer ‘n dubbelvolgings benadering om in reële tyd posisionele data van die werker en die werk-stuk te kry. Die OpenNI en OpenCV biblioteke word onderskeidelik gebruik om skeletale volging en beeld erkenning uit te voer. Die skeletale volger bepaal posisionele data van spesifieke gewrigte van die werker, terwyl die beeld erkenning komponent, 'n SURF implementering gebruik om 'n spesifieke werk-stuk binne die opname raam te identifiseer en te volg. Hierdie volgings tegnieke is berekenings intensief. Om werklike tyd uitvoering van die program te verseker, is Nvidia se CUDA gereedskapstel en liggewig boublokke geimplementeer. Die produktiwiteit meting-stelsel is 'n aaneenlopende monsterneming benadering van werk monsterneming. Die spoed van die werker se handbewegings en nabyheid aan die werkstuk word gebruik om die werker te klassifiseer as in een van vier moontlike toestande; besig, staties, onaktief of buite die raam. Benewens die werker gebaseerde metings, word daar ook data oor werkstukke bereken. Dit sluit in die aantal werkstukke verwerk deur 'n spesifieke werker, sowel as die gemiddelde en variasie in verwerkings tye. Die risiko-berekening is 'n outomatiese benadering van die hersiende NIOSH opheffing vergelyking. Die stelsel bereken wanneer die werker kontak maak en/of breek met die werkstuk en maak gebruik van die gewrigsposisies wat die skeletale volger aandui om die veranderlikes wat in die vermenigvuldigers gebruik word te bepaal. Die vermenigvuldigers word gebruik om die aanbevole maksimum gewig en die opheffing indeks te bereken. Die opheffing indeks dui aan of daar ‘n risiko vir die werker is om muskuloskeletale versteuring te ontwikkel. Benewens dui die vermenigvuldigers aan watter elemente die grootste bydra tot die risiko van die opheffingstaak maak. Die gebruiker-koppelvlak-ontwerp verseker dat die stelsel maklik is om te gebruik. Die koppelvlak vertoon ook die resultate van die studie sodat ontleders op enige tyd werker prestasie kan evalueer in reële tyd. Die outomatiese stelsel stel dus ontleders in staat om vinnig te reageer sodat probleme reggestel kan word. Die stelsel verminder ook die kompleksiteit vir die uitvoering van studies en dit elimineer menslike foute. Die tyd en koste vereis om die studie te doen, word verminder en die stelsel kan ‘n permanente instelling op fabriekvloere geword. Die ontwikkeling van die outomatiese stelsel maak die deur oop vir verdere ontwikkeling van die stelsel om uiteindelik daartoe te lei dat meer gedetailleerde evaluering van produktiwiteit en risiko bepaal kan word.

Syfte: Mot bakgrund kring en ökad turism i europeiska storstäder (Statista, u.å.) har syftet med studien varit att studera Barcelona som exempel för att bidra med en djupare förståelse kring hur turister och lokalbefolkning uppfattar varandra i stadsmiljöer med högt turistantal. Samt undersöka hur turismen har förändrat stadens stadskärna och miljö (Duran, 2005). Metod: I studien har ett kvalitativt tillvägagångssätt applicerats i form av semistrukturerade intervjuer och insamling av vetenskapliga artiklar till empirin. Tolv personer som har intervjuats som har koppling till Barcelona och det sammanfattas i empirin, tillsammans med de vetenskapliga artiklarna. Slutsatser: Den här studie har undersökt Barcelona som exempel för att belysa massturism som är ett omfattande problem som även går att finna i andra europeiska storstäder. Genom de insamlade intervjuerna och de vetenskapliga artiklar påvisades det att Barcelona har fått både positiva och negativa effekter av den massiva turism som finns i staden. Utifrån de insamlade intervjusvaren kunde slutsatsen dras att den sociala aspekten har störst negativ inverkan på lokalbefolkningen i staden. / Purpose: Against the background of increased tourism in European metropolitan areas (Statista, u.o.), the purpose of the study has been to study Barcelona as an example to contribute a deeper understanding of how tourists and locals perceive each other in urban environments with a high tourist number. As well as investigating how tourism has changed the city's city center and environment (Duran, 2005). Methodology: In this study, a qualitative approach has been applied in the form of semi-structured interviews and the gathering of scientific articles of empirical data. Twelve people interviewed who are connected to Barcelona and this is summarized in empirical section, along with the scientific articles. Conclusions: This study has explored Barcelona as an example to illustrate mass tourism, which is a major problem that can be found in other European cities. Through the collected interviews and the scientific articles, it was demonstrated that Barcelona has had both positive and negative effects of the massive tourism that exists in the city. Based on the collected interview answers, it could be concluded that the social aspect has the most negative impact on local people in the city.

Made available in DSpace on 2016-06-02T20:18:07Z (GMT). No. of bitstreams: 1 TeseRSP.pdf: 2033512 bytes, checksum: d5ddb9118edecd3afca2376359856f6d (MD5) Previous issue date: 2006-04-25 / Load handling activities impose great overloads on the musculoskeletal system, increasing the risk of injuries. The fact that these handling activities are considered risky had led to several studies regarding load lifting, lowering, pulling and pushing. The results obtained certainly allowed many findings about influence of different variables on risk factors of these activities. However, other studies are needed, especially about risks by load carrying activities, since the literature has not dealt extensively with this topic. Thus, studies have been carried out about load handling, leading to 4 scientific papers. Study one aimed at comparing two groups of workers, with and without musculoskeletal symptoms in the upper limbs when they performed simulated tasks of handling techniques as to trunk movements and load support. Movements analysis was quantified by a flexible electrogoniometer and contact between load and trunk, by load cells. Nine asymptomatic and 10 symptomatic industrial workers were evaluated. An ANOVA was performed to compare results between symptomatic and asymptomatic workers. Most of the symptomatic workers supported the load on their trunk, whilst most of the asymptomatic did not. Higher values of lumbar flexion occurred for the symptomatic workers (p<0,05). The objective of the second study was ti describe trunk movements in sedentary subjects, and in workers with and without musculoskeletal symptoms, when carrying loads in simulated tasks. The 38 subjects who participated in this study were divided into 4 groups, consisting of 9 male students, 10 female students, 10 female symptomatic industrial workers and 9 asymptomatic industrial workers. The trunk movements of all subjects were recorded by biaxial back electrogoniometer when carrying loads between surfaces of different heights. An analysis of variance for repeated measures were performed, which was followed by the Duncan post hoc test for comparison of anthropometrical data between subjects, amplitude of movement, and time spent in each movement per group and per experimental condition. The height of the surfaces to which the loads were carried to or from, significantly influenced the trunk positions during handling (p<0,01), as if subjects were anticipating the target position whilst handling. Also more time was spent in flexion (p<0,01) than in extension. These aspects increase the risks of possible injury in such activities. The objective of the third study was to describe the kinds of grip used during handling activities of 5Kgf and 10 Kgf loads between surfaces of different height and to quantify flexion/extension movements and wrist radial and ulnar deviations quantified by electrogoniometry. Ten male volunteers participated in this study handled a box between surfaces of different heights. The activities was performed to evaluate significant differences between the anthropometry of volunteers´ hands and between movements used for load handling and different heights. The results showed that the surface heights to which the objects were handled significantly influenced (p=0,000) joint amplitudes, nevertheless there wasn t any difference in the movements for different load masses handled (p=0,43). Time over what is considered advisable was spent in radial deviation when handling involved high surfaces. The fourth study aimed at evaluating the anterior-posterior movements of the trunk and the time spent in task performance by experienced and inexperienced subjects during load handling activities to different target surfaces. The 36 subjects who participated in this study were healthy males, divided into groups of 16 and 20, experienced and inexperience respectively, in the performance of load handling activities. The activities consisted of carrying the 7Kg and 15Kg boxes from a surface at a fixed height to another at a variable height. Lumbar thoracic movements were quantified by a flexible electrogoniometer. Significant differences were found in the time spent to perform the handling between the groups (p<0,008) and between the loads (p<0,000). However, there was no significant difference in the trunk movemets between the groups (p>0,005) and the loads (p>0,005). Surfaces heights to which the box was transported significantly influenced trunks movements (p<0,000). / As atividades de manuseio de carga geram grandes sobrecargas ao sistema músculoesquelético, aumentando com isso os riscos de lesões. O fato dessas atividades de manuseio serem consideradas de risco fez com que muitos estudos fossem realizados considerando situações de levantamento, abaixamento, puxar e empurrar cargas. Os resultados obtidos certamente permitiram muitas descobertas sobre as diferentes variáveis envolvidas e os fatores de risco dessas atividades. Contudo, são necessidade outros estudos principalmente sobre os riscos gerados por atividades de carregamento de carga, já que a literatura cientifica aborda muito pouco essa temática. Assim, foram então realizados estudos sobre atividade de carregamento de carga que geraram 4 (quatro) artigos científicos. O objetivo do Estudo I foi comparar dois grupos de trabalhadores com e sem sintomas músculo-esqueléticos em membros superiores quando realizaram tarefas simuladas de manuseio, quanto aos movimentos do tronco e suporte da carga. A análise do movimento foi realizada por meio de um eletrogoniômetro flexível, o contato entre a carga e o tronco foi mensurado por meio de células de carga. Foram avaliados 9 trabalhadores assintomáticos e 10 sintomáticos. Para comparar os resultados entre sintomáticos e assintomáticos utilizou-se uma ANOVA. A maioria dos trabalhadores sintomáticos apoiou a carga no tronco enquanto que a maioria dos assintomáticos não. A amplitude de movimento de flexão lombar que ocorreram no grupo de trabalhadores sintomáticos foram bem maiores do que no grupo de assintomáticos (p<0,05). O objetivo do segundo estudo foi descrever os movimentos do tronco em indivíduos sedentários e em trabalhadores com e sem sintomas músculo-esqueléticos. Participaram do estudo 38 indivíduos sendo divididos em 4 grupos, 9 homens estudantes, 10 mulheres estudantes, 10 trabalhadoras sintomáticas e 9 trabalhadoras assintomáticas. Os movimentos do tronco foram registrados por um eletrogoniômetro biaxial de tronco durante o carregamento de carga para diferentes alturas de superfícies. Uma análise de variância ANOVA para medidas repetidas foi aplicada. Os resultados mostraram que a altura das superfícies para a qual a carga seria levada influenciou significativamente os movimentos do tronco (p<0,01) e que mais tempo foi gasto em movimentos de flexão quando comparados à extensão do tronco (p<0,01). O objetivo do terceiro estudo foi descrever os tipos de preensão empregados durante atividades de manuseio de cargas de 5 e 10Kgf entre superfícies de alturas diferentes e, quantificar os movimentos de flexão/extensão, desvio radial e ulnar do punho registrados por meio da eletrogoniômetria. Participaram 10 voluntários do sexo masculino que manusearam uma caixa entre superfícies de diferentes alturas. A atividade foi filmada para identificar os tipos de preensão empregados durante a tarefa. Uma análise de univariância foi utilizada para avaliar diferenças significativas entre a antropometria das mãos dos voluntários, e entre os movimentos utilizados para o manuseio de cargas para diferentes alturas. Os resultados mostraram que as alturas das superfícies para as quais as cargas eram manuseadas influenciaram significativamente (p=0,000) as amplitudes articulares, contudo não houve diferença significativa nos movimentos para as diferentes massas das cargas manuseadas (p=0,43). O gasto tempo acima das faixas de amplitude consideradas recomendáveis foi expressivo para os movimentos de desvio radial quando os manuseios envolviam superfícies altas. O quarto estudo objetivou avaliar os movimentos antero-posteriores do tronco e o tempo gasto na realização da tarefa, por indivíduos experientes e inexperientes, durante atividade de carregamento de cargas para diferentes superfícies alvo. Participaram do estudo 36 homens saudáveis, sendo 16 experientes e 20 inexperientes na realização da atividade de manuseio de carga. A atividade consistiu no transporte de caixa com massa de 7 e 15kg, partindo de uma superfície com altura fixa e depositavam a caixa em uma outra superfície de altura variável. Os movimentos da coluna tóraco-lombar foram registrados com um eletrogoniômetro flexível. Foram encontradas diferenças significativas no tempo gasto para realizar os manuseios entre grupos (p<0,008) e entre cargas (p<0,000). Contudo não houve diferença significativa (p>0,05). As alturas das superfícies para as quais a caixa era deslocada influenciaram significativamente os movimentos do tronco (p<0,000).

The focus of this investigation was an analysis of the work demands being placed on South African automotive industry workers as there is a recognised problem with regard to the prevalence of musculoskeletal disorders (MSDs). Preliminary work was conducted to highlight the dominant risks and areas which elicited higher numbers of MSDs within the chosen automotive plant. An area of concern was highlighted through medical record analysis and the use of risk assessment tools, thereby prioritising the need for ergonomic intervention. In particular, the effects of varying restricted and overhead work heights on the biomechanical, physiological and psychophysical responses of an individual were investigated. Twenty-eight subjects were required to complete sixteen conditions. The conditions consisted of the adoption of restricted and upright overhead static postures, with half requiring the holding of four kilograms of weight in the hands and the remaining eight conditions having no weight. Testing was carried out using an electromyography unit, ergospirometer and a perceptual Body Discomfort Map and Scale. This involved a habituation and testing session. The results of the testing revealed the biomechanical and physiological responses were dependant on the change in height. Body discomfort was also shown to be variable over the changing height conditions. This indicates that there is a significant effect of height on an individual’s responses during overhead work. The extreme restricted (-200mm and -100mm) and upright (+300mm and +400mm) overhead conditions within this study were limiting, as they elicited the highest muscle activation, physiological responses and body discomfort ratings. Positions that are preferable to adopt, which were identified from the results in this study, indicate conditions closer to head height (0mm and +100mm) were favourable. The results therefore illustrate how awkward working postures during work are likely to elicit higher demands from an individual, which could lead to an increased risk for the development of a musculoskeletal disorder. The added factor of weight elicited significant results over all variables, excluding a respiratory The focus of this investigation was an analysis of the work demands being placed on South African automotive industry workers as there is a recognised problem with regard to the prevalence of musculoskeletal disorders (MSDs). Preliminary work was conducted to highlight the dominant risks and areas which elicited higher numbers of MSDs within the chosen automotive plant. An area of concern was highlighted through medical record analysis and the use of risk assessment tools, thereby prioritising the need for ergonomic intervention. In particular, the effects of varying restricted and overhead work heights on the biomechanical, physiological and psychophysical responses of an individual were investigated. Twenty-eight subjects were required to complete sixteen conditions. The conditions consisted of the adoption of restricted and upright overhead static postures, with half requiring the holding of four kilograms of weight in the hands and the remaining eight conditions having no weight. Testing was carried out using an electromyography unit, ergospirometer and a perceptual Body Discomfort Map and Scale. This involved a habituation and testing session. The results of the testing revealed the biomechanical and physiological responses were dependant on the change in height. Body discomfort was also shown to be variable over the changing height conditions. This indicates that there is a significant effect of height on an individual’s responses during overhead work. The extreme restricted (-200mm and -100mm) and upright (+300mm and +400mm) overhead conditions within this study were limiting, as they elicited the highest muscle activation, physiological responses and body discomfort ratings. Positions that are preferable to adopt, which were identified from the results in this study, indicate conditions closer to head height (0mm and +100mm) were favourable. The results therefore illustrate how awkward working postures during work are likely to elicit higher demands from an individual, which could lead to an increased risk for the development of a musculoskeletal disorder. The added factor of weight elicited significant results over all variables, excluding a respiratory individual.

Background: Agriculture plays a vital role in the economy of any industrially developing country, including South Africa. In the Eastern Cape of South Africa citrus farming is a significant contributor to the local economy (Johnson et al., 2005). The harvesting phase of citrus farming is performed manually and exposes workers to physical risks, which can lead to the development of musculoskeletal disorders. In particular, the standard harvesting bag comprises of a single shoulder strap and promotes asymmetrical load carriage which results in shoulder and lower back pain complaints. The current study compared the physiological (EMG), perceptual (RPE), usability (PUEU) and productivity effects of two new harvesting bag designs (a hip belt and a backpack bag design) to the standard harvesting bag design. This was performed in a laboratory as well as a field setting. Methods (Laboratory phase): 36 participants (12 males and 24 females) were assigned to one worker group. The “tall ladder worker” group was comprised of only males and the “step ladder worker” and “ground worker” group of females. Each participant was required to simulate a citrus harvesting task while utilizing each of the bag designs on different days. On each day/test session, participants performed three harvesting cycles. Muscle activity was measured throughout the entire testing session and RPE were recorded at the end of each cycle. Results (Laboratory phase): The EMG and RPE results indicate that the backpack design was the most ideal design to reduce asymmetry, while the standard harvesting bag design was the worst. Although not significant, there was greater muscle asymmetry (p=0.109) and a significantly higher perceived exertion when using the standard bag (p=0.0004), in comparison to using the backpack. Methods (Field phase): 17 Xhosa-speaking citrus harvesters (6 females and 11 males) participated in this study. Each harvester worked with one of the three bag designs on a different day. Productivity of each worker was assessed every hour by recording the number of bags filled with fruit and at the end of the shift. A Perceived Usefulness & Ease of Use questionnaire was presented to each participant to obtain feedback on worker acceptance to the new bag designs. Results (Field phase): A general trend in support of the hip belt bag design over the other two bag designs were found, even within the different worker demographic groups (age, sex and worker experience). The workers perceived less exertion (7.98 ± 1.86) and were more productive (9.90 ± 2.11 bags/hour) when using the hip belt design; they also found this bag the most useful (1.02 ± 0.09) and easy to use (1.07 ± 0.25). In contrast, the backpack bag design had significantly poorer responses when compared to the other two bag designs and this was evident in all the dependent variables assessed (RPE, productivity and PUEU). Conclusion: The results from the laboratory phase supported the expectation that the backpack bag design reduces asymmetry and hence, is more suitable than the standard harvesting bag. However, results from the field show that the hip belt bag design was the most preferred and the backpack was the least preferred. Bao & Shahnavaz (1989) highlight the need for ergonomics researcher to convey laboratory findings into the field context. However, as shown by the current study, there are numerous challenges associated with field work, making it difficult for laboratory findings to be successfully conveyed to the field. Limitations and Recommendations: For the laboratory phase of the project, no biomechanical and cardiovascular responses were assessed. However, for a holistic approach, these variables should be considered in future studies. Due to high variability from one harvesting cycle to another, more than three harvesting cycles should also be performed to accurately replicate the harvesting process as done in the field over extended durations of time. For the field phase, data should be collected from more than one citrus farm and thus a larger sample size could be obtained. This would improve the validity of the study. In addition to this, data should be collected for a full working day, especially if environmental conditions are not a hindrance, as well as for a whole season, since workloads vary, depending on the time of the harvesting season. / Name on Graduation Programme: Bassey-Duke, Elizabeth Missan

Les habitats côtiers à fonds meubles sont essentiels dans le cycle de vie de nombreuses espèces de poissons. Ces habitats ont pour caractéristique d’être peu étendus mais sont aussi très productifs et jouent à ce titre un rôle de nourricerie pour les juvéniles de poissons bentho-démersaux. Les fortes abondances de proies semblent être l’une des raisons principales de la présence des juvéniles au sein de ces habitats. Bien que déjà étudié, le caractère limitant de la nourriture disponible fait toujours l’objet de débats dans la communauté scientifique. Une des raisons principales est que l’étude des milieux côtiers est rendue complexe par la diversité des facteurs entrant en jeu dans le développement des jeunes stades de poissons. A partir du cas d’étude de la baie de Vilaine, une des nourriceries les plus productives du golfe de Gascogneles recherches menées dans cette thèse visent à définir le rôle du facteur alimentaire dans l’organisation de la nourricerie et dans sa capacité à soutenir le développement des juvéniles de poissons. Le fil conducteur de cette thèse est donc de déterminer si le facteur alimentaire limite la production de juvéniles. Les résultats montrent une forte exploitation de la production alimentaire ainsi qu'une superposition spatiale entre les densités de juvéniles de poissons et de leurs proies. La cohérence de ces résultats tend à soutenir l'hypothèse que la capacité d'accueil de la baie de Vilaine est atteinte et donc que le facteur alimentaire est limitant. Les implications de ce mécanisme de régulation sur la dynamique des populations nourricer / Soft sediment coastal habitats are essential in the life cycle of numerous fishes. These habitats are spatially-limited but very productive, and play a key role of nursery for the juveniles of benthic and demersal fishes. High abundance of prey seems to be one of the main reasons of the presence of juvenile fish within these habitats. Although widely studied, the limiting aspect of the feeding factor is still debated in the scientific community. One of the main reasons is that studying coastalhabitats is complex because numerous factors influence the development of the first life stages of fish. From the study case of the Bay of Vilaine, one of the most productive nurseries of the Bay of Biscay, research conducted in this thesis aims to define the role of the feeding factor in the organisation of the nursery and in its capacity to support the development of juvenile fish. The common thread of this thesis is thus to determine if the feeding factor limits the juvenile fish production. The results show a strong exploitation of the food production by the juvenile fish community and a spatial match between the densities of juvenile fish and their prey. The consistency of these results tends to support that the hypothesis that the carrying capacity of the Bay of Vilaine is reached, and that the feeding factor is limiting. The consequences of this regulation process on the dynamics of nursery-dependent fish populations are discussed.