982 resultados para Effect of temperature


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A quasi-Poisson generalized linear model combined with a distributed lag non-linear model was used to quantify the main effect of temperature on emergency department visits (EDVs) for childhood diarrhea in Brisbane from 2001 to 2010. Residual of the model was checked to examine whether there was an added effect due to heat waves. The change over time in temperature-diarrhea relation was also assessed. Both low and high temperatures had significant impact on childhood diarrhea. Heat waves had an added effect on childhood diarrhea, and this effect increased with intensity and duration of heat waves. There was a decreasing trend in the main effect of heat on childhood diarrhea in Brisbane across the study period. Brisbane children appeared to have gradually adapted to mild heat, but they are still very sensitive to persistent extreme heat. Development of future heat alert systems should take the change in temperature-diarrhea relation over time into account.

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The dynamic nature of tissue temperature and the subcutaneous properties, such as blood flow, fatness, and metabolic rate, leads to variation in local skin temperature. Therefore, we investigated the effects of using multiple regions of interest when calculating weighted mean skin temperature from four local sites. Twenty-six healthy males completed a single trial in a thermonetural laboratory (mean ± SD): 24.0 (1.2) °C; 56 (8%) relative humidity; < 0.1 m/s air speed). Mean skin temperature was calculated from four local sites (neck, scapula, hand and shin) in accordance with International Standards using digital infrared thermography. A 50 x 50 mm square, defined by strips of aluminium tape, created six unique regions of interest, top left quadrant, top right quadrant, bottom left quadrant, bottom right quadrant, centre quadrant and the entire region of interest, at each of the local sites. The largest potential error in weighted mean skin temperature was calculated using a combination of a) the coolest and b) the warmest regions of interest at each of the local sites. Significant differences between the six regions interest were observed at the neck (P < 0.01), scapula (P < 0.001) and shin (P < 0.05); but not at the hand (P = 0.482). The largest difference (± SEM) at each site was as follows: neck 0.2 (0.1) °C; scapula 0.2 (0.0) °C; shin 0.1 (0.0) °C and hand 0.1 (0.1) °C. The largest potential error (mean ± SD) in weighted mean skin temperature was 0.4 (0.1) °C (P < 0.001) and the associated 95% limits of agreement for these differences was 0.2 to 0.5 °C. Although we observed differences in local and mean skin temperature based on the region of interest employed, these differences were minimal and are not considered physiologically meaningful.

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Species of Liposcelis psocids have emerged as major pests of stored grain in Australia in recent years. Several populations have been detected with high resistance to phosphine, the major chemical treatment. Highest resistance has been detected in the cosmopolitan species Liposcelis bostrychophila. As part of a national resistance management strategy to maintain the viability of phosphine, we are developing minimum effective dosage regimes (concentration x time) required to control all life stages of resistant L. bostrychophila at a range of grain temperatures. Four concentrations of phosphine, 0.1, 0.17, 0.3 aid 1 mg/L, were evaluated for their effectiveness against strongly resistant L. bostrychophila at a series of fumigation temperatures: 20, 25, 30 and 35°C. Results were recorded as the least number of days taken to achieve population extinction. We found that, at any fixed concentration of phosphine, time to population extinction decreased as fumigation temperature increased from 20 to 30°C. For example, at 0.1 mg/L, it took more than 14 days at 20°C to completely control these insects, whereas at 30°C it took only seven days. Increase in fumigation temperature from 25OC to 30°C dramatically reduced the exposure period needed to achieve population extinction of resistant psocids. For example, a dose of 0.17 mg/L over six days at 30°C completely controlled strongly resistant L. bostrychophila populations that can survive at 1 mg/L and 25°C over the same exposure period. Findings from our study will be used to formulate recommendations for registered dosage rates and fumigation periods for use in Australia.

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Copper aluminum oxide films were prepared by direct current (dc) reactive magnetron sputtering under various substrate temperatures in the range of 303–648 K and systematically studied their physical properties. The physical properties of the films were strongly affected by the substrate temperature. The films formed at substrate temperatures <373 K were amorphous while those deposited at higher substrate temperatures (≥373 K) were polycrystalline in nature. The electrical properties of the films enhanced with substrate temperature due to the improved crystallinity. The Hall mobility of 9.4 cm2/V s and carrier concentration of 3.5 × 1017 cm−3 were obtained at the substrate temperature of 573 K. The optical band gap of the films decreased from 3.87 to 3.46 eV with the increase of substrate temperature from 373 to 573 K.

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A study of the effect of N2 reservoir temperature on the small-signal gain in a downstream-mixing 16 μm CO2-N2 GDL is presented. It is shown that the small-signal gain decreases with the increase of N2 reservoir temperature. The conditions for reversing this trend are discussed and the results are presented in the form of graphs.

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By using a perturbation technique, the Korteweg-de Vries equation is derived for a mixture of warm-ion fluid and hot, isothermal electrons. Stationary solutions are obtained for this equation and are compared with the corresponding solutions for a mixture consisting of cold-ion fluid and hot, isothermal electrons.

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Astaxanthin is a powerful antioxidant with various health benefits such as prevention of age-related macular degeneration and improvement of the immune system, liver and heart function. To improve the post-harvesting stability of astaxanthin used in food, feed and nutraceutical industries, the biomass of the high astaxanthin producing alga Haematococcus pluvialis was dried by spray- or freeze-drying and under vacuum or air at − 20 °C to 37 °C for 20 weeks. Freeze-drying led to 41 higher astaxanthin recovery compared to commonly-used spray-drying. Low storage temperature (− 20 °C, 4 °C) and vacuum-packing also showed higher astaxanthin stability with as little as 12.3 ± 3.1 degradation during 20 weeks of storage. Cost-benefit analysis showed that freeze-drying followed by vacuum-packed storage at − 20 °C can generate AUD600 higher profit compared to spray-drying from 100 kg H. pluvialis powder. Therefore, freeze-drying can be suggested as a mild and more profitable method for ensuring longer shelf life of astaxanthin from H. pluvialis.

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Using a perturbation technique, we derive Modified Korteweg—de Vries (MKdV) equations for a mixture of warm-ion fluid (γ i = 3) and hot and non-isothermal electrons (γ e> 1), (i) when deviations from isothermality are finite, and (ii) when deviations from isothermality are small. We obtain stationary solutions for these equations, and compare them with the corresponding solutions for a mixture of warm-ion fluid (γ i = 3) and hot, isothermal electrons (γ i = 1).

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A study of compression waves produced in a viscous heat-conducting gas by the impulsive start of a one-dimensional piston and by the inpulsive change of piston wall temperature is made using Laplace Transform Technique for Prandt1 number unity. Expressions for velocity, temperature and density have also been obtained using small-time expansion procedure in this case. For arbitrary Prandt1 number solutions have been developed using large-time expansion procedure. A number of graphs exhibiting the distribution of the fluid velocity, temperature and density have been drawn.

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Effect of disorder on the electrical resistance near the superconducting transition temperature in the paracoherence region of high temperature YBa2CU3O7-delta (YBCO) thin film superconductor is reported. For this, c-axis oriented YBa2Cu3O7-delta thin films having superconducting transition width varying between 0.27 K and 6 K were deposited using laser ablation and high pressure oxygen sputtering techniques. Disorder in these films was further created by using 100 MeV oxygen and 200 MeV silver ions with varying fluences. It is observed that the critical exponent in the paracoherence region for films with high transition temperature and small transition width is in agreement with the theoretically predicted value (gamma = 1.33) and is not affected by disorder, while for films with lower transition temperature and larger transition width the value of exponent is much larger as compared to that theoretically predicted and it varies from sample to sample and usually changes with disorder induced by radiation. This difference in the behaviour of the exponent has been explained on the basis of differences in the strength of weak links and the transition between temperatures T. and T, is interpreted as a percolation like transition with disorder. (c) 2006 Elsevier B.V. All rights reserved.

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The effect of scarification, ploughing and cross-directional plouhing on temperature conditions in the soil and adjacent air layer have been studied during 11 consecutive growth periods by using an unprepared clear-cut area as a control site. The maximum and minimum temperatures were measured daily in the summer months, and other temperature observations were made at four-hour intervals by means of a Grant measuring instrument. The development of the seedling stand was also followed in order to determine its shading effect on the soil surface. Soil preparation decreased the daily temperature amplitude of the air at the height of 10 cm. The maximum temperatures on sunny days were lower in the tilts of the ploughed and in the humps of the cross-directional ploughed sites compared with the unprepared area. Correspondingly, the night temperatures were higher and so the soil preparation considerably reduced the risk of night frost. In the soil at the depth of 5 cm, soil preparation increased daytime temperatures and reduced night temperatures compared with unprepared area. The maximum increase in monthly mean temperatures was almost 5 °C, and the daily variation in the surface parts of the tilts and humps increased so that excessively high temperatures for the optimal growth of the root system were measured from time to time. The temperature also rose at the depths of 50 and 100 cm. Soil preparation also increased the cumulative temperature sum. The highest sums accumulated during the summer months were recorded at the depth of 5 cm in the humps of cross-directional ploughed area (1127 dd.) and in the tilts of the ploughed area (1106 dd.), while the corresponding figure in the unprepared soil was 718 dd. At the height of 10 cm the highest temperature sum was 1020 dd. in the hump, the corresponding figure in the unprepared area being 925 dd. The incidence of high temperature amplitudes and percentage of high temperatures at the depth of 5 cm decreased most rapidly in the humps of cross-directional ploughed area and in the ploughing tilts towards the end of the measurement period. The decrease was attributed principally to the compressing of tilts, the ground vegetation succession and the growth of seedlings. The mean summer temperature in the unprepared area was lower than in the prepared area and the difference did not diminish during the period studied. The increase in temperature brought about by soil preparation thus lasts at least more than 10 years.