968 resultados para Temperature of animals.


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Growth patterns and cropping were evaluated over the season for the everbearing strawberry 'Everest' at a range of temperatures (15-27degreesC) in two light environments (ambient and 50% shade). The highest yield was recorded for unshaded plants grown at 23degreesC, but the optimum temperature for vegetative growth was 15degreesC. With increasing temperature fruit number increased, but fruit weight decreased. Fruit weight was also significantly reduced by shade, and although 'Everest' showed a degree of shade tolerance in vegetative growth, yield was consistently reduced by shade. Shade also reduced the number of crowns developed by the plants over the course of the season, emphasising that crown number was ultimately the limiting factor for yield potential. We conclude that, in contrast to Junebearers which partition more assimilates to fruit at temperatures around 15degreesC (Le Miere et al., 1998), optimised cropping in the everbearer 'Everest' is achieved at the significantly higher temperature of 23degreesC. These findings have significance for commercial production, in which protection tends to reduce light levels but increase average temperature throughout the season.

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Tungsten carbide/oxide particles have been prepared by the gel precipitation of tungstic acid in the presence of an organic gelling agent [10% ammonium poly(acrylic acid) in water, supplied by Ciba Specialty Chemicals]. The feed solution; a homogeneous mixture of sodium tungstate and ammonium poly(acrylic acid) in water, was dropped from a 1-mm jet into hydrochloric acid saturated hexanol/concentrated hydrochloric acid to give particles of a mixture of tungstic acid and poly(acrylic acid), which, after drying in air at 100 degrees C and heating to 900 degrees C in argon for 2 h, followed by heating in carbon dioxide for a further 2 h and cooling, gives a mixture of WO, WC, and a trace of NaxWO3, with the carbon for the formation of WC being provided by the thermal carbonization of poly(acrylic acid). The pyrolyzed product is friable and easily broken down in a pestle and mortar to a fine powder or by ultrasonics, in water, to form a stable colloid. The temperature of carbide formation by this process is significantly lower (900 degrees C) than that reported for the commercial preparation of tungsten carbide, typically > 1400 degrees C. In addition, the need for prolonged grinding of the constituents is obviated because the reacting moieties are already in intimate contact on a molecular basis. X-ray diffraction, particle sizing, transmission electron microscopy, surface area, and pore size distribution studies have been carried out, and possible uses are suggested. A flow diagram for the process is described.

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The X-ray diffraction pattern of glassy poly(2-hydroxypropyl ether of bisphenol A) is studied at room temperature on oriented samples in order to associate its different peaks to different structural correlations. On the other hand, X-ray diffraction patterns have been obtained at different temperatures from Tg − 50 K up to Tg + 50 K for the above-mentioned polymer. Attention has been paid to the evolution with temperature of the position of the wide diffraction maximum corresponding to interchain correlations in the polymer. The temperature evolution of this parameter shows a marked discontinuity just at the glass transition temperature.

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Hybrid vigour may help overcome the negative effects of climate change in rice. A popular rice hybrid (IR75217H), a heat-tolerant check (N22), and a mega-variety (IR64) were tested for tolerance of seed-set and grain quality to high-temperature stress at anthesis at ambient and elevated [CO2]. Under an ambient air temperature of 29 °C (tissue temperature 28.3 °C), elevated [CO2] increased vegetative and reproductive growth, including seed yield in all three genotypes. Seed-set was reduced by high temperature in all three genotypes, with the hybrid and IR64 equally affected and twice as sensitive as the tolerant cultivar N22. No interaction occurred between temperature and [CO2] for seed-set. The hybrid had significantly more anthesed spikelets at all temperatures than IR64 and at 29 °C this resulted in a large yield advantage. At 35 °C (tissue temperature 32.9 °C) the hybrid had a higher seed yield than IR64 due to the higher spikelet number, but at 38 °C (tissue temperature 34–35 °C) there was no yield advantage. Grain gel consistency in the hybrid and IR64 was reduced by high temperatures only at elevated [CO2], while the percentage of broken grains increased from 10% at 29 °C to 35% at 38 °C in the hybrid. It is concluded that seed-set of hybrids is susceptible to short episodes of high temperature during anthesis, but that at intermediate tissue temperatures of 32.9 °C higher spikelet number (yield potential) of the hybrid can compensate to some extent. If the heat tolerance from N22 or other tolerant donors could be transferred into hybrids, yield could be maintained under the higher temperatures predicted with climate change.

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The rheology and microstructure of Mozzarella-type curds made from buffalo and cows’ milk were measured at gelation temperatures of 28, 34 and 39 °C after chymosin addition. The maximum curd strength (G′) was obtained at a gelation temperature of 34 °C in both types of bovine milk. The viscoelasticity (tan δ) of both curds was increased with increasing gelation temperature. The rennet coagulation time was reduced with increase of gelation temperature in both types of milk. Frequency sweep data (0.1–10Hz was recorded 90 min after chymosin addition, and both milk samples showed characteristics of weak viscoelastic gel systems. When both milk samples were subjected to shear stress to break the curd system at constant shear rate, 95 min after chymosin addition, the maximum yield stress was obtained at the gelation temperatures of 34 °C and 28 °C in buffalo and cows’ curd respectively. The cryo-SEM and CLSM techniques were used to observe the microstructure of Mozzarella-type curd. The porosity was measured using image J software. The cryo-SEM and CLSM micrographs showed that minimum porosity was observed at the gelation temperature of 34 °C in both types of milk. Buffalo curd showed minimum porosity at similar gelation temperature when compared to cows’ curd. This may be due to higher protein concentration in buffalo milk.

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A continuous band of high ion temperature, which persisted for about 8 h and zigzagged north-south across more than five degrees in latitude in the dayside (07:00– 15:00MLT) auroral ionosphere, was observed by the EISCAT VHF radar on 23 November 1999. Latitudinal gradients in the temperature of the F-region electron and ion gases (Te and Ti , respectively) have been compared with concurrent observations of particle precipitation and field-perpendicular convection by DMSP satellites, in order to reveal a physical explanation for the persistent band of high Ti , and to test the potential role of Ti and Te gradients as possible markers for the open-closed field line boundary. The north/south movement of the equatorward Ti boundary was found to be consistent with the contraction/expansion of the polar cap due to an unbalanced dayside and nightside reconnection. Sporadic intensifications in Ti , recurring on _10-min time scales, indicate that frictional heating was modulated by time-varying reconnection, and the band of high Ti was located on open flux. However, the equatorward Ti boundary was not found to be a close proxy of the open-closed boundary. The closest definable proxy of the open-closed boundary is the magnetosheath electron edge observed by DMSP. Although Te appears to be sensitive to magnetosheath electron fluxes, it is not found to be a suitable parameter for routine tracking of the open-closed boundary, as it involves case dependent analysis of the thermal balance. Finally, we have documented a region of newly-opened sunward convecting flux. This region is situated between the convection reversal boundary and the magnetosheath electron edge defining the openclosed boundary. This is consistent with a delay of several minutes between the arrival of the first (super-Alfv´enic) magnetosheath electrons and the response in the ionospheric convection, conveyed to the ionosphere by the interior Alfv´en wave. It represents a candidate footprint of the low-latitude boundary mixing layer on sunward convecting open flux

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In vitro studies have provided conflicting evidence of temperature changes in the tooth pulp chamber after low-level laser irradiation of the tooth surface. The present study was an in vitro evaluation of temperature increases in the human tooth pulp chamber after diode laser irradiation (GaAlAs, lambda = 808 nm) using different power densities. Twelve human teeth (three incisors, three canines, three premolars and three molars) were sectioned in the cervical third of the root and enlarged for the introduction of a thermocouple into the pulp chamber. The teeth were irradiated with 417 mW, 207 mW and 78 mW power outputs for 30 s on the vestibular surface approximately 2 mm from the cervical line of the crown. The highest average increase in temperature (5.6A degrees C) was observed in incisors irradiated with 417 mW. None of the teeth (incisors, canines, premolars or molars) irradiated with 207 mW showed temperature increases higher than 5.5A degrees C that could potentially be harmful to pulp tissue. Teeth irradiated with 78 mW showed lower temperature increases. The study showed that diode laser irradiation with a wavelength of 808 nm at 417 mW power output increased the pulp chamber temperature of certain groups of teeth, especially incisors and premolars, to critical threshold values for the dental pulp (5.5A degrees C). Thus, this study serves as a warning to clinicians that ""more"" is not necessarily ""better"".

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We determined by means of photoluminescence measurements the dependence on temperature of the transition energy of excitons in GaAs/Al(x)Ga(1-x)As quantum wells with different alloy concentrations (with different barrier heights). Using a fitting procedure, we determined the parameters which describe the behavior of the excitonic transition energy as a function of temperature according to three different theoretical models. We verified that the temperature dependence of the excitonic transition energy does not only depend on the GaAs material but also depends on the barrier material, i.e. on the alloy composition. The effect of confinement on the temperature dependence of the excitonic transition is discussed.

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Continuous casting is a casting process that produces steel slabs in a continuous manner with steel being poured at the top of the caster and a steel strand emerging from the mould below. Molten steel is transferred from the AOD converter to the caster using a ladle. The ladle is designed to be strong and insulated. Complete insulation is never achieved. Some of the heat is lost to the refractories by convection and conduction. Heat losses by radiation also occur. It is important to know the temperature of the melt during the process. For this reason, an online model was previously developed to simulate the steel and ladle wall temperatures during the ladle cycle. The model was developed as an ODE based model using grey box modeling technique. The model’s performance was acceptable and needed to be presented in a user friendly way. The aim of this thesis work was basically to design a GUI that presents steel and ladle wall temperatures calculated by the model and also allow the user to make adjustments to the model. This thesis work also discusses the sensitivity analysis of different parameters involved and their effects on different temperature estimations.

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O presente trabalho teve como objetivo estudar o efeito de diferentes temperaturas-ambiente durante a primeira semana de vida de pintos de corte sob parâmetros zootécnicos, desenvolvimento visceral e crescimento ósseo. Foram utilizados 240 pintos de um dia, alojados em 3 câmaras climáticas, com temperaturas constantes de 20, 25 e 35°C do 1° ao 7° dia de vida. Diariamente, o consumo de água e ração, bem como o peso vivo, o peso relativo do fígado, moela, coração, saco vitelino e bursa de Fabricius foram avaliados. A tíbia e o fêmur também foram pesados e o comprimento e espessura (diâmetro médio) mensurados. As aves criadas a 20°C ganharam menos peso e consumiram menos ração do que aves mantidas a 25°C e menos água do que aves mantidas a 35°C. O peso relativo do fígado, coração e moela foram afetados pela temperatura ambiente, entretanto, não foi observado efeito da temperatura de criação sobre o peso do saco vitelino e bursa de Fabricius. Os dados mostraram que todos os parâmetros ósseos pesquisados aumentaram com a idade das aves. A temperatura ambiente não afetou a espessura da tíbia e do fêmur, mas foi observado um aumento significativo no peso e comprimento dos ossos com o aumento da temperatura ambiente. Os resultados desse experimento mostraram que o estresse por frio (20°C) reduziu o crescimento ósseo bem como o peso vivo das aves, durante os primeiros sete dias após a eclosão.

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O canistel é uma fruteira originada no México e América Central, sendo introduzida no Brasil em 1986. As plantas apresentam porte médio, porém podem atingir até 15 metros de altura; as folhas medem cerca de 10 a 25 cm; as flores são completas e pequenas, e o fruto apresenta coloração amarela quando maduro, com polpa esbranquiçada e sabor doce. A propagação pode ser realizada por semente ou por enxertia. em vista da quase total ausência de informações sobre a cultura e a possibilidade de cultivo comercial, realizou-se o presente trabalho, no qual se avaliou o efeito da temperatura na porcentagem de germinação de sementes. Foi verificado que as melhores taxas foram obtidas à temperatura de 30ºC e as menores a 15ºC, 20ºC e 40ºC, sendo esta última a pior delas.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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A jabuticabeira (Myrciaria spp.) é uma fruteira originada do centro-Sul do Brasil e apresenta tipos diferentes. É uma árvore de tamanho médio, com tendência a formar copa com grande número de ramos desde pouco acima do solo. Uma característica considerada como limitante para a cultura comercial dessa frutífera é o grande período juvenil, aconselhando-se então produzir bons porta-enxertos de pés-francos e enxertar as variedades desejadas, ou ainda por outros processos vegetativos. Objetivando-se avaliar a influência da temperatura na germinação de sementes de três clones de jabuticabeira, realizou-se um experimento em condições de laboratório. Observou-se que há influência da temperatura na porcentagem de germinação, sendo que, nas mais baixas temperaturas (15ºC e 20ºC), foi verificada uma maior porcentagem de germinação para os três clones em estudo. Quando do uso da temperatura de 35ºC, dois clones tiveram apenas 8% de germinação, enquanto, para o outro, foi verificado 35%. Estes dados mostram a possibilidade de ocorrência de variabilidade entre clones de jabuticabeira.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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