651 |
The effect of work related mechanical stress on the peripheral temperature of the handVardasca, Ricardo Ângelo Rosa January 2010 (has links)
The evolution and developments in modern industry have resulted a wide range of occupational activities, some of which can lead to industrial injuries. Due to the activities of occupational medicine, much progress has been made in transforming the way that operatives perform their tasks. However there are still many occupations where manual tasks have become more repetitive, contributing to the development of conditions that affect the upper limbs. Repetitive Strain Injury is one classification of those conditions which is related to overuse of repetitive movement. Hand Arm Vibration Syndrome is a subtype of this classification directly related to the operation of instruments and machinery which involves vibration. These conditions affect a large number of individuals, and are costly in terms of work absence, loss of income and compensation. While such conditions can be difficult to avoid, they can be monitored and controlled, with prevention usually the least expensive solution. In medico-legal situations it may be difficult to determine the location or the degree of injury, and therefore determining the relevant compensation due is complicated by the absence of objective and quantifiable methods. This research is an investigation into the development of an objective, quantitative and reproducible diagnostic procedure for work related upper limb disorders. A set of objective mechanical provocation tests for the hands have been developed that are associated with vascular challenge. Infrared thermal imaging was used to monitor the temperature changes using a well defined capture protocol. Normal reference values have been measured and a computational tool used to facilitate the process and standardise image processing. These objective tests have demonstrated good discrimination between groups of healthy controls and subjects with work related injuries but not individuals, p < 0.05, and are reproducible. A maximum value for thermal symmetry of 0.5±0.3oC for the whole upper limbs has been established for use as a reference. The tests can be used to monitor occupations at risk, aiming to reduce the impact of these conditions, reducing work related injury costs, and providing early detection. In a medico-legal setting this can also provide important objective information in proof of injury and ultimately in objectively establishing whether or not there is a case for compensation.
|
652 |
Temperature and its effects on some maritime plants in BritainPalin, M. Anne January 1979 (has links)
The physiological ecology of five coastal species has been examined with respect to temperature and its effect on survival and distribution. The aims of the study have been to establish whether any direct correlation exists between distribution and the responses of the plants to temperature at different stages in the life cycle. The species Tinder consideration were the northern Ligusticum scoticum and Mertensia maritima and the southern Crithmum maritimum, Limonium binervosum and Glaucium flavum. Highest germination percentages for each species were found at temperatures close to those associated with the season favourable for germination in the natural habitat. Northern species had higher temperature requirements than the southern, corresponding to spring/ summer and autumn or spring germination respectively. Root respiration, measured as oxygen uptake, was found to be twice as great in the northern Ligusticum and Mertensia as in the southern Crithmum and Limonium over a range of experimental temperatures. This varied to some extent with time and temperature of pretreatment. The single experiment on the southern Glauci.um showed rates similar to those of the northern species. Arrhenius plots' of respiration data for the northern species showed a break in gradient at the upper end of the experimental temperature range which correlated well with apparently limiting July mean temperatures from the distribution maps. The southern Crithmum showed a break at lower temperature range close to the limiting January mean temperature. The response of Limonium to experimental temperature depended on the pretreatment; upper range breaks were shown after low pretreatment temperatures, and lower range breaks after higher pretreatment temperatures. The single experiment on Glaucium gave a straight line Arrhenius plot. Carbohydrate analyses of the same pretreated plants yielded additional information relevant to the survival and thus to the distribution in relation to temperature. The southern Crithmum had the highest starch content at all temperatures while the northern Ligusticum and Mertensia had less. Ratios of soluble sugar to starch were greatest in the northern species, possibly reflecting displacement of the equilibrium from starch to soluble sugar at lower temperatures. Overall a connection has been demonstrated between the direct effects of temperature on the plants and the limitation of distribution by temperature. This is clearest for the two northern species, Ligusticum scoticum and Mertensia maritima, less definite for the southern Crithmum maritimiim, and only suggested for Limonium binervosum with its apparently less simple temperature responses. Glaucium flavum appears anomalous and requires further study.
|
653 |
Temperature adaptations in perennial grasses from climatically contrasting habitatsSchneider, Albrecht January 1980 (has links)
This thesis investigates physiological mechanisms underlying temperature adaptations in perennial grasses. A comparative approach was employed by using pairs of species that have been collected from lowland sites in thermally contrasting habitats up to 2000 km apart on a north-south direction. The population samples from northern latitudes, i.e. from cooler climates, had higher growth rates at 12°C than southern provenances. Dark respiration rates between 5 and 25°C did not differ between provenances; but acclimatization at 10°C increased the respiration rate in all northern population samples, whereas some southern population samples reduced their respiration rate as a response to acclimatization at 10°C. Northern provenances showed a greater activity of carbohydrate formation in light after periods of 48 hours starvation in darkness. This property could be attributed to the higher activity of RuBP-carboxylase in northern genotypes. No evidence was found that the higher activities are due to higher enzyme concentrations in these genotypes. The enzyme exhibited lower energies of activation in northern provenances in the range 5 - 15°C Activation energies for succinate dehydrogenase in isolated mitochondria were higher for northern population samples in the range 10 - 25°C. Higher specific activities were found for malate dehydrogenase from northern plants between 5 and 25°C. In this temperature range the apparent energies of activation were lower for northern plants. The enzyme displayed positive thermal modulation in both northern and southern provenances. Temperature changes had generally a greater effect on northern provenances. The significance of these findings is discussed in the light of previous reports in the literature and in relation to a possible advantage in the plant's native habitat.
|
654 |
Non-resonant microwave absorption studies in SmFeAs(O,F) iron pnictide superconductorOnyancha, Robert Birundu 03 1900 (has links)
As an electromagnetic response detection technique, non-resonant microwave absorption (NRMA) has been without doubt, one of the fundamental tools in characterizing high temperature superconductors (HTSC). The technique can explicitly give factual information on flux pinning, granularity, magnetization, and detection of iota superconducting phases among many more.
The emergence of iron pnictides superconductors has brought an enormous impact on HTSC field due to their relatively high 𝑇c, high critical fields 𝐵c2, huge critical current density and low anisotropy. Accordingly, they look appealing candidates in industrial applications more especially in high magnetic field applications. As of yet, its electromagnetic response particularly the low field microwave absorption (LFMA) or the non-resonant microwave absorption (NRMA) is relatively unknown.
Consequently, in this work, systematic studies have been done on SmFeAs(O,F), superconductors to determine the low field sweep microwave absorption. Furthermore, effect of varying temperature, microwave power and field modulation amplitude on NRMA line shape have been addressed and the results obtained are compared with NRMA results of cuprates superconductors.
Interestingly, the NRMA line shape has been found to evolve as a function of temperature, microwave power and field modulation amplitude. A structure i.e a broad peak 1 and a narrow peak 2 have been identified. Furthermore, the line shape shows a phase reversal at moderately high microwave power.
This dissertation presents the theoretical background of superconductors, experimental techniques, working principles of the equipments, results, discussions and conclusions. As pertains to the future work, recommendations have been suggested in trying other forms of sample and also different sample materials of iron based superconductors to fully understand the NRMA and ensure a progressive and continuous work in this field. Also, we will carry out extensive studies on critical current density, fluxon dynamics and irreversibility fields on iron-based superconductors by means of NRMA technique. / Physics / M. Sc. (Physics)
|
655 |
Seasonal changes in the heat production of an African small mammal, Rhabdomys pumilioWelman, Shaun January 2012 (has links)
Endothermy refers to the ability of an individual to produce heat from internal sources, and allows animals to maintain a body temperature that is higher than their external environment. Although much is known about the benefits of endothermy, its origin is highly debated. Nonetheless, due to environmental variation, endotherms have to regulate their heat production (thermogenesis) in order to remain normothermic. An endotherms regulatory response seems to be body size dependent. Keeping warm during cold periods is energetically expensive, and for small mammals this is exacerbated by their high rate of heat loss due to high surface area to volume ratios. To compensate for the heat lost, small non-hibernating mammals must increase their level of thermogenesis. Much of our current understanding of thermogenic responses of small mammals is derived from laboratory acclimated animals, and studies on naturally acclimatized animals are uncommon. In addition, most studies on thermogenesis tend to focus on one level of animal organisation, such as subcellular, tissue or in-vivo, but seldom integrate these data. The aim of this study was to measure year-round variation in thermogenesis across all levels of organisation, using naturally acclimatized Rhabdomys pumilio individuals from the Nelson Mandela Metropolitan University, Port Elizabeth. It was predicted that the level of thermogenesis would be significantly higher during winter relative to other seasons in order to cope with the low ambient temperatures (Tas) experienced during this season. Open flow respirometry was used to measure the animal's oxygen consumption, as a proxy for metabolism; the by product of which is heat production. The animal's basal metabolic rate (BMR), nonshivering thermogenesis (NST) capacity and summit metabolic rate (MSUM) were measured. A Western blot analysis was used to determine the expression of uncoupling protein 1 (UCP 1) in the animals' brown adipose tissue (BAT), as well as determine its relative concentration. The cytochrome c oxidase (COX) activity of the animals' visceral organs and BAT was measured, as an indicator of the tissues' metabolic activity. COX activity was determined as the difference in the tissues' oxygen consumption before and after the addition of horse cytochrome c.
|
656 |
The effects of drought and high temperature stress on reproduction, physiology, and yield of spring and winter wheatShroyer, Kyle J. January 1900 (has links)
Doctor of Philosophy / Department of Agronomy / P. V. Vara Prasad / Drought and high temperature are major detriments to global wheat production. Wheat varies in its susceptibility to drought and high temperature stress. Three experiments were performed to address the challenges of drought and high temperature stress in wheat. The first experiment consisted of 256 genotypes of spring wheat and 301 genotypes of winter wheat, field screened for yield traits related to drought tolerance, in irrigated and dryland experiments. The experimental designs for the first experiment were both augmented incomplete block designs with one-way or row-column blocking. This experiment was performed at the Ashland Bottom Research Farm, south of Manhattan, KS, between 2011-2013. From this experiment, three conclusions were made: wheat genotypes vary widely in their responses between dryland and irrigated treatments and this variation can be used in future experiments or breeding tolerant genotypes. The number of seeds per unit of area, total biomass per unit area, and the average weight of one thousand seeds, were the best yield traits for predicting yield in both irrigated and dryland environments. Twenty genotypes were selected for future research based on their susceptibility or tolerance to drought. The second experiment was performed in the greenhouse facilities to observe the source-sink relationship of spring wheat genotype Seri 82 under drought and defoliation. The experiment was a randomized complete block design with a split-plot treatment arrangement. Post-anthesis cessation of watering and defoliation were the treatments. Both water stress and defoliation affected seed yield and total biomass. The major effect of post-anthesis water stress was a decrease in single seed weight. Defoliation affected the source-sink relationship by reducing the source strength of the leaves. This caused the stem to contribute more to overall yield. The defoliation also caused the remaining leaves to compensate for the removed leaves. The final experiment evaluated the changes in seed-filling rate and duration of three winter wheat genotypes during high temperature stress. High temperature stress reduced the duration of seed fill and increased the rate, differently in each genotype. Higher yields in the winter wheat growing regions, susceptible to post-anthesis high temperature stress, may be possible through selection of cultivars with faster seed-filling rates and/or duration of seed filling.
|
657 |
Variação sazonal da temperatura corpórea no lagarto Teiú, Tupinambis merianae (Squamata, Lacertilia, Teiidae) /Ribas, Elis Regina. January 2005 (has links)
Resumo: Com o propósito de obter um perfil da variação sazonal e diária da temperatura corpórea (Tc) do lagarto teiú, T. merianae, sensores/ registradores de temperatura ("data-loggers") foram cirurgicamente implantados, em oito espécimes adultos de ambos os sexos.Os lagartos foram mantidos em baias ao ar livre e acompanhados durante um ano. As temperaturas dos microambientes ao sol, na sombra e na toca foram igualmente registradas. A Tc dos teiús mostrou variação sazonal e diária relacionadas às mudanças nas temperaturas dos microambientes e aos ajustes fisiológicos nas taxas de aquecimento e de resfriamento. A Tc média diária seguiu um ritmo circadiano, com temperaturas mínimas no início da manhã, aumento entre 12h e 16h e queda gradual ao final da tarde. A Tc media diária de atividade durante a estação de atividade (agosto/dezembro) ficou em 33,6oC l 1,4 oC. A taxa média de aquecimento foi cinco vezes maior que a de resfriamento durante a estação de atividade, o que permitiu ao animal manter sua Tc acima da temperatura do abrigo e da sombra. Com o declínio da temperatura ambiente em meados do outono, os teiús entram nos abrigos e o ritmo circadiano de variação da Tc diminuiu. Durante a estação de dormência, a Tc máxima diária foi de 20,1oC l 0,7oC e seguiu a variação térmica do abrigo. Durante a estação de atividade, T. merianae controla sua Tc por termorregulação. Nos meses frios o teiú entra em dormência com a queda da Tc, que acompanha passivamente a temperatura da toca / Abstract: In order to obtain a profile of the seasonal and daily variation of the body temperature (Tc) of the tegu lizard, Tupinambis merianae, TidBit® electronic data loggers (temperature probes) were surgically implanted in eight adult individuals. The lizards were kept in outdoor pens and monitored over a one year period. Teguþs body temperature showed seasonal and daily variations, which were related to the changes in the temperatures of the microhabitats (sun, shade, and burrow) and, possibly, to changes in heating and cooling rates. The daily average Tc followed a circadian rhythm characterized by lowest temperatures occurring at dawn, then temperature rapidly increases from soon after sunrise until noon, Tc is then maintained in high levels until late afternoon (~16h) when the lizards stop activity, retreat to the burrow, and let body temperature to drop. The mean Tc experienced by the tegus during activity at the warm season (August/December) was 33.6 oC l 1,4 oC. During the active season, the heating rate of the lizards during the morning was five times greater than the cooling rate experienced during the night. As a result, tegus seems to be able to maintain their Tc above the temperature of the burrow and of the shade along the night time. With declining air temperatures towards the end of autumn, tegus enter their burrows, goes into dormancy, and the circadian rhythm in Tc become less prominent. During this season, Tc followed passively the variation of the burrowþs temperature / Orientador: Augusto Shinya Abe / Coorientador: Denis Otávio Vieira de Andrade / Banca: José Eduardo Bicudo / Banca: Monique Van Sluys / Mestre
|
658 |
Comportamento reologico da polpa de manga (Mangifera indica L-Keitt) / Rheological behavior of mango pulp (Mangifera indica L-Keitt)Bezerra, Jose Raniere Mazile Vidal 26 July 2018 (has links)
Orientador: Carlos Alberto Gasparetto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-26T10:48:15Z (GMT). No. of bitstreams: 1
Bezerra_JoseRaniereMazileVidal_D.pdf: 32355992 bytes, checksum: 484ef63e0b0cbcd9ace1a86835808b69 (MD5)
Previous issue date: 2000 / Resumo: Neste trabalho experimental foi determinado o comportamento reológico da polpa de manga variedade Keitt na faixa de temperatura de 10°C a 60°C. A polpa integral foi produzida em planta piloto e refinada num "finisher" com peneira de 1,6mm. Foram também utilizadas a polpa integral centrifugada e a integral despectinizada. As análises reológicas foram conduzidas num reômetro Haake Rotovisco RV-20 com geometrias de cilindros concêntricos e de placas paralelas. Os reogramas foram descritos pelos modelos de Ostwaldde-Waelle (Lei da Potência), Casson, Herschel-Bulkley e Mizrahi-Berk na faixa de taxa de deformação 50-900s-1 e todas as amostras apresentaram comportamento pseudoplástico. Os resultados obtidos mostraram que o sistema de cilindros concêntricos e de placas paralelas pq 45, com distância de 1,Omm, são os mais adequados à caracterização reológica das polpas ensaiadas. Os resultados também foram analisados em termos de viscosidade aparente, calculadas a partir do modelo de Mizrahi-Berk, através do qual foram ajustados os dados obtidos com cilindros concêntricos. O efeito da temperatura sobre os parâmetros reológicos que representam o índice de consistência (KM)foram ajustados, usando-se a equação de Arrhenius ln(KM) Al+Bl/T. Nos casos dos modelos de Mizrahi-Berk e Lei da Potência o índice de comportamento (nM)foi ajustado por uma função do tipo nM -A2+B2T. As polpas integral e despectinizada, a partir de 40°C, mostraram um aumento da viscosidade aparente / Abstract: Experiments were conducted in order to know the rheological behaviour ofmango pulp (Keitt) in the temperature range lO-60°C. Whole pulp was produced at pilot plant and refined in a finisher with 1.6mmmesh. Whole centrifuged and whole despectinized pulps were also analysed. Rheometry was conducted with a Haake-Rotovisco RV-20 system using both concentric cylinders and parallel plate. Rheograms were fitted with models by Ostwaldde-Waelle, Casson, Herschel-Bulkley and Mizrahi-Berk for the shear rate within the range 50-900s-1, showing pseudoplastic behaviour for alI pulps. Aparent viscosity were obtained from calculations using the Mizrahi-Berk fitted parameters in to data produced with concentric cylinders. Consistency index (KM)of the best fitted models were described in terms of temperature using Arrhenius equation ln(KM) Al+Bl/T and the flow behaviour index (nM)was fitted to nM A2+B2T. Whole and despectinized pulps showed an increase in apparent viscosity beyhond 40°C / Doutorado / Doutor em Engenharia de Alimentos
|
659 |
Estudo das propriedades dos picos TL 4, 5 e 6 no LiF:MgBLAK, ANA R. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:23:23Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:56:21Z (GMT). No. of bitstreams: 1
00923.pdf: 967727 bytes, checksum: e4ec44feb110fa74e5c797458a912619 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Fisica, Universidade de Sao Paulo - IF/USP
|
660 |
Comportamento reologico de chocolates ao leite sem fibras e enriquecido com fibras soluveis / Rheological behavior of chocolates without milk fortified with fiber and soluble fiberGozzo, Angela Maria 31 March 2003 (has links)
Orientador: Carlos Alberto Gasparetto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T09:36:55Z (GMT). No. of bitstreams: 1
Gozzo_AngelaMaria_M.pdf: 4762020 bytes, checksum: 0d5dc688b48d897c862795ea7fe818cb (MD5)
Previous issue date: 2003 / Resumo: Neste trabalho foi determinado o comportamento reológico de chocolate sem fibras e chocolate enriquecido com fibras solúveis. As amostras foram produzidas em planta piloto, aplicando-se a mesma formulação e processo para ambas as amostras, variando somente a quantidade de açúcar e fibras. As análises reológicas foram realizadas em um reômetro de cilindros concêntricos marca HAAKE Rotovisco RV-20, em temperaturas de 38, 40, 42, 45 e 50°C, na faixa de deformação de 0 a 250 s-1. Os pontos experimentais dos reogramas foram ajustados aos modelos reológicos de Casson, Bingham e Windhab e todos descreveram adequadamente o comportamento reológico dos chocolates. Os parâmetros ajustados pelos modelos de Bingham e de Windhab foram muito próximos, indicando que os termos adicionados ao modelo de Windhab não influenciaram no comportamento reológico das amostras. O melhor ajuste reológico foi obtido pelo modelo de Casson, apresentando coeficientes de correlação próximos a um (1.0) e uma diferença entre os valores experimentais e preditos pelo modelo próxima a zero. Para analisar o comportamento da tensão de cisalhamento em relação ao tempo, os experimentos foram realizados à taxas de deformação constantes (50, 100, 150, 200 e 250 s-1) para cada temperatura. Os resultados obtidos mostraram que a viscosidade plástica e a tensão residual são maiores para as amostras de chocolate enriquecido com fibras, as quais não apresentaram comportamento tixotrópico. O efeito da temperatura sobre os parâmetros reológicos foi descrito pelo modelo de Arrhenius, observou-se que a energia de ativação é maior para as amostras de chocolate enriquecidas com fibras / Abstract: The concern of this work was to determine the rheological behaviour of chocolate without fibers and chocolate enriched with soluble fibers. Those samples were produced at pilot plant, using the same recipe and process, varying sugar and fibers amount. The rheological analyses were realized in a HAAKE Rotovisco RV-20 system using concentric cylinders, at 38, 40, 42, 45 and 50°C for shear rate at 0 - 250 s-1. Rheograms were fitted according to the following models: Bingham, Casson e Windhab. The parameters adjusted by the Bingham and Windhab models were satisfactory, indicating that the terms added to the Windhab model, didn't have influence in the rheological behaviour of the samples. The best rheological adjustment was obtained by Casson model where the plastic viscosity decreased with temperature and the yield stress had a unsteady behaviour for both samples. The results showed that the plastic viscosity and the yield stress the largest for the chocolate enriched with fibers, which didn't present thixotropy behaviour. The Arrhenius model describe the temperature effect on rheology behaviour of samples. The results also showed that activation energy for enriched chocolate with soluble fibers is bigger than activation energy for chocolates without fibers / Mestrado / Mestre em Engenharia de Alimentos
|
Page generated in 0.0374 seconds