965 resultados para temperature sensitive
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The paper examines the influence of unemployment insurance on the duration of employment spells in Canada using the 1988–90 Labour Market Activity Survey. The primary focus of the paper is to evaluate whether estimated UI effects are sensitive to the degree to which institutional rules and regulations governing UI eligibility and entitlement are explicitly modelled. The key result of the paper is that it is indeed important to allow for institutional detail when estimating unemployment insurance effects. Estimates using simple proxies for eligibility indicate small, often insignificant UI effects. The size and significance of the effects rise as more realistic versions of the variables are adopted. The estimates using the eligibility variables incorporating the greatest level of institutional detail suggest that a jump in the hazard rate by a factor of 2.3 may not be an unreasonable estimate of the effect.
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This paper develops analytical distributions of temperature indices on which temperature derivatives are written. If the deviations of daily temperatures from their expected values are modelled as an Ornstein-Uhlenbeck process with timevarying variance, then the distributions of the temperature index on which the derivative is written is the sum of truncated, correlated Gaussian deviates. The key result of this paper is to provide an analytical approximation to the distribution of this sum, thus allowing the accurate computation of payoffs without the need for any simulation. A data set comprising average daily temperature spanning over a hundred years for four Australian cities is used to demonstrate the efficacy of this approach for estimating the payoffs to temperature derivatives. It is demonstrated that expected payoffs computed directly from historical records are a particularly poor approach to the problem when there are trends in underlying average daily temperature. It is shown that the proposed analytical approach is superior to historical pricing.
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Background Women undergoing Cesarean Section (CS) are vulnerable to the adverse effects associated with perioperative core temperature drop, in part due to the tendency for CS to be performed under neuraxial anesthesia, blood and fluid loss, and vasodilation. Inadvertent perioperative hypothermia (IPH) is a common condition that affects patients undergoing surgery of all specialties and is detrimental to all age groups, including neonates. Previous systematic reviews on IPH prevention largely focus on either adult or all ages populations, and have mainly overlooked pregnant or CS patients as a distinct group. Not all recommendations made by systematic reviews targeting all adult patients may be transferable to CS patients. Alternative, effective methods for preventing or managing hypothermia in this group would be valuable. Objectives To synthesize the best available evidence in relation to preventing and/or treating hypothermia in mothers after CS surgery. Types of participants Adult patients over the age of 18 years, of any ethnic background, with or without co-morbidities, undergoing any mode of anesthesia for any type of CS (emergency or planned) at healthcare facilities who have received interventions to limit or manage perioperative core heat loss were included. Types of intervention(s) Active or passive warming methods versus usual care or placebo, that aim to limit or manage core heat loss as applied to women undergoing CS were included. Types of studies Randomized controlled trials (RCTs) that met the inclusion criteria, with reduction of perioperative hypothermia a primary or secondary outcome were considered. Types of outcomes Primary outcome: maternal core temperature measured during the preoperative, intraoperative and postoperative phases of care Secondary outcomes: newborn core temperature at birth, umbilical pH obtained immediately after birth, Apgar scores, length of Post Anesthetic Care Unit (PACU) stay, maternal thermal comfort. Search strategy A comprehensive search was undertaken of the following databases from their inception until May 2012: ProQuest, Web of Science, Scopus, Dissertation and Theses PQDT (via ProQuest), Current Contents, CENTRAL, Mednar, OpenGrey, Clinical Trials. There were no language restrictions. Methodological quality Retrieved papers were assessed for methodological quality by two independent reviewers prior to inclusion using JBI software. Disagreements were resolved via consultation with the third reviewer. An assessment of quality of the included papers was also made in relation to five key quality factors. Data collection Two independent reviewers extracted data from the included papers using a previously piloted customized data extraction tool. Results 12 studies with a combined total of 719 participants were included. Three broad intervention groups were identified; intravenous (IV) fluid warming, warming devices, leg wrapping. IV fluid warming, whether administered intraoperatively or preoperatively, was found to be effective at maintaining maternal (but not neonatal) temperature and preventing shivering, but does not improve thermal comfort. The effectiveness of IV fluid warming on Apgar scores and umbilical pH remains unclear. Warming devices, including forced air warming and under body carbon polymer mattresses, were effective at preventing hypothermia and reduced shivering, however were most effective if applied preoperatively. The effectiveness of warming devices to improve thermal comfort remains unclear. Preoperative forced air warming appears to aid maintenance of neonatal temperature, while intraoperative forced air warming does not. Forced air warming was not effective at improving Apgar scores and the effects for umbilical pH remain unclear. Conclusions Intravenous fluid warming, by any method, improves maternal temperature and reduces shivering for women undergoing CS. Preoperative body warming devices also improve maternal temperature, in addition to reducing shivering.
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A low temperature lignocellulose pretreatment process was developed using acid-catalysed mixtures of alkylene carbonate and alkylene glycol. Pretreatment of sugarcane bagasse with mixtures of ethylene carbonate (EC) and ethylene glycol (EG) was more effective than that with mixtures of propylene carbonate (PC) and propylene glycol (PG). These mixtures were more effective than the individual components in making bagasse cellulose more amenable to cellulase digestion. Glucan digestibilities of ≥87% could be achieved with a wide range of EC to EG ratios from 9:1 to 1:1 (w/w). Pretreatment of bagasse by the EC/EG mixture with a ratio of 4:1 in the presence of 1.2% H2SO4 at 90 °C for 30 min led to the highest glucan enzymatic digestibility of 93%. The high glucan digestibilities obtained under these acidic conditions were due to (a) the ability of alkylene carbonate to cause significant biomass size reduction, (b) the ability of alkylene glycol to cause biomass defibrillation, (c) the ability of alkylene carbonate and alkylene glycol to remove xylan and lignin, and (d) the magnified above attributes in the mixtures of alkylene carbonate and alkylene glycol.
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During food drying, many other changes occur simultaneously, resulting in an improved overall quality. Among the quality attributes, the structure and its corresponding color influence directly or indirectly other properties of food. In addition, these quality attributes are affected by process conditions, material components and the raw structure of the foodstuff. In this work, the temperature distribution within food materials during microwave drying has been taken into consideration to observe its role in color modification. In order to determine the temperature distribution of microwave-dried food (apple), a thermal imaging camera has been used. The image acquired from the digital camera has been analysed using image J software in order to get the color change of fresh and dried apple. The results show that temperature distribution plays an important role in determining the quality of the food. The thermal imaging camera was deployed to observe the temperature distribution within food materials during drying. It is clearly observed from the higher value of (ERGB =102) and the uneven color change that uneven temperature distribution can influence customer perceptions of the quality of dried food. Simulation of a mathematical model of temperature distribution during microwave drying can make it possible to predict the colour and texture of the microwaved food.
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Most studies examining the temperature–mortality association in a city used temperatures from one site or the average from a network of sites. This may cause measurement error as temperature varies across a city due to effects such as urban heat islands. We examined whether spatiotemporal models using spatially resolved temperatures produced different associations between temperature and mortality compared with time series models that used non-spatial temperatures. We obtained daily mortality data in 163 areas across Brisbane city, Australia from 2000 to 2004. We used ordinary kriging to interpolate spatial temperature variation across the city based on 19 monitoring sites. We used a spatiotemporal model to examine the impact of spatially resolved temperatures on mortality. Also, we used a time series model to examine non-spatial temperatures using a single site and the average temperature from three sites. We used squared Pearson scaled residuals to compare model fit. We found that kriged temperatures were consistent with observed temperatures. Spatiotemporal models using kriged temperature data yielded slightly better model fit than time series models using a single site or the average of three sites' data. Despite this better fit, spatiotemporal and time series models produced similar associations between temperature and mortality. In conclusion, time series models using non-spatial temperatures were equally good at estimating the city-wide association between temperature and mortality as spatiotemporal models.
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The growth of graphene on SiC/Si substrates is an appealing alternative to the growth on bulk SiC for cost reduction and to better integrate the material with Si based electronic devices. In this paper, we present a complete in-situ study of the growth of epitaxial graphene on 3C SiC (111)/Si (111) substrates via high temperature annealing (ranging from 1125˚C to 1375˚C) in ultra high vacuum (UHV). The quality and number of graphene layers have been thoroughly investigated by using x-ray photoelectron spectroscopy (XPS), while the surface characterization have been studied by scanning tunnelling microscopy (STM). Ex-situ Raman spectroscopy measurements confirm our findings, which demonstrate the exponential dependence of the number of graphene layer from the annealing temperature.
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A large subsurface, elevated temperature anomaly is well documented in Central Australia. High Heat Producing Granites (HHPGs) intersected by drilling at Innamincka are often assumed to be the dominant cause of the elevated subsurface temperatures, although their presence in other parts of the temperature anomaly has not been confirmed. Geological controls on the temperature anomaly remain poorly understood. Additionally, methods previously used to predict temperature at 5 km depth in this area are simplistic and possibly do not give an accurate representation of the true distribution and magnitude of the temperature anomaly. Here we re-evaluate the geological controls on geothermal potential in the Queensland part of the temperature anomaly using a stochastic thermal model. The results illustrate that the temperature distribution is most sensitive to the thermal conductivity structure of the top 5 km. Furthermore, the results indicate the presence of silicic crust enriched in heat producing elements between and 40 km.
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The current approach for protecting the receiving water environment from urban stormwater pollution is the adoption of structural measures commonly referred to as Water Sensitive Urban Design (WSUD). The treatment efficiency of WSUD measures closely depends on the design of the specific treatment units. As stormwater quality can be influenced by rainfall characteristics, the selection of appropriate rainfall events for treatment design is essential to ensure the effectiveness of WSUD systems. Based on extensive field investigation of four urban residential catchments and computer modelling, this paper details a technically robust approach for the selection of rainfall events for stormwater treatment design using a three-component model. The modelling outcomes indicate that selecting smaller average recurrence interval (ARI) events with high intensity-short duration as the threshold for the treatment system design is the most feasible since these events cumulatively generate a major portion of the annual pollutant load compared to the other types of rainfall events, despite producing a relatively smaller runoff volume. This implies that designs based on small and more frequent rainfall events rather than larger rainfall events would be appropriate in the context of efficiency in treatment performance, cost-effectiveness and possible savings in land area needed.
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Highly sensitive infrared cameras can produce high-resolution diagnostic images of the temperature and vascular changes of breasts. Wavelet transform based features are suitable in extracting the texture difference information of these images due to their scale-space decomposition. The objective of this study is to investigate the potential of extracted features in differentiating between breast lesions by comparing the two corresponding pectoral regions of two breast thermograms. The pectoral regions of breastsare important because near 50% of all breast cancer is located in this region. In this study, the pectoral region of the left breast is selected. Then the corresponding pectoral region of the right breast is identified. Texture features based on the first and the second sets of statistics are extracted from wavelet decomposed images of the pectoral regions of two breast thermograms. Principal component analysis is used to reduce dimension and an Adaboost classifier to evaluate classification performance. A number of different wavelet features are compared and it is shown that complex non-separable 2D discrete wavelet transform features perform better than their real separable counterparts.
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Collagen crosslinking (CXL) has shown promising results in the prevention of the progression of keratoconus and corneal ectasia. However, techniques for in vivo and in situ assessment of the treatment are limited. In this study, ex vivo porcine eyes were treated with a chemical CXL agent (glutaraldehyde), during which polarization sensitive optical coherence tomography (PS-OCT) recordings were acquired simultaneously to assess the sensitivity of the technique to assess changes in the cornea. The results obtained in this study suggest that PS-OCT may be a suitable technique to measure CXL changes in situ and to assess the local changes in the treated region of the cornea.
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Background The association between temperature and mortality has been examined mainly in North America and Europe. However, less evidence is available in developing countries, especially in Thailand. In this study, we examined the relationship between temperature and mortality in Chiang Mai city, Thailand, during 1999–2008. Method A time series model was used to examine the effects of temperature on cause-specific mortality (non-external, cardiopulmonary, cardiovascular, and respiratory) and age-specific non-external mortality (<=64, 65–74, 75–84, and > =85 years), while controlling for relative humidity, air pollution, day of the week, season and long-term trend. We used a distributed lag non-linear model to examine the delayed effects of temperature on mortality up to 21 days. Results We found non-linear effects of temperature on all mortality types and age groups. Both hot and cold temperatures resulted in immediate increase in all mortality types and age groups. Generally, the hot effects on all mortality types and age groups were short-term, while the cold effects lasted longer. The relative risk of non-external mortality associated with cold temperature (19.35°C, 1st percentile of temperature) relative to 24.7°C (25th percentile of temperature) was 1.29 (95% confidence interval (CI): 1.16, 1.44) for lags 0–21. The relative risk of non-external mortality associated with high temperature (31.7°C, 99th percentile of temperature) relative to 28°C (75th percentile of temperature) was 1.11 (95% CI: 1.00, 1.24) for lags 0–21. Conclusion This study indicates that exposure to both hot and cold temperatures were related to increased mortality. Both cold and hot effects occurred immediately but cold effects lasted longer than hot effects. This study provides useful data for policy makers to better prepare local responses to manage the impact of hot and cold temperatures on population health.
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High-quality YBa2Cu3O7-δ films grown on (001) single-crystal Y-ZrO2 substrates by pulsed laser deposition have been studied as a function of substrate temperature using transmission electron microscopy. A transition from epitaxial films to c-axis oriented polycrystalline films was observed at 740°C. An intermediate, polycrystalline, BaZrO3 layer was formed from a reaction between the film and the substrate. A dominant orientation relationship of [001] YBCO//[001]int. layer//[001]YSZ and [110] YBCO//[110]int. layer//[100]YSZ was observed. The formation of grain boundaries in the films resulted in an increased microwave surface resistance and a decreased critical-current density. The superconducting transition temperature remained fairly constant at about 90 K.
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Non-periodic structural variation has been found in the high Tc cuprates, YBa2Cu3O7-x and Hg0.67Pb0.33Ba2Ca2Cu 3O8+δ, by image analysis of high resolution transmission electron microscope (HRTEM) images. We use two methods for analysis of the HRTEM images. The first method is a means for measuring the bending of lattice fringes at twin planes. The second method is a low-pass filter technique which enhances information contained by diffuse-scattered electrons and reveals what appears to be an interference effect between domains of differing lattice parameter in the top and bottom of the thin foil. We believe that these methods of image analysis could be usefully applied to the many thousands of HRTEM images that have been collected by other workers in the high temperature superconductor field. This work provides direct structural evidence for phase separation in high Tc cuprates, and gives support to recent stripes models that have been proposed to explain various angle resolved photoelectron spectroscopy and nuclear magnetic resonance data. We believe that the structural variation is a response to an opening of an electronic solubility gap where holes are not uniformly distributed in the material but are confined to metallic stripes. Optimum doping may occur as a consequence of the diffuse boundaries between stripes which arise from spinodal decomposition. Theoretical ideas about the high Tc cuprates which treat the cuprates as homogeneous may need to be modified in order to take account of this type of structural variation.
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c-axis-oriented YBa2Cu3O7-x (YBCO) thin films were laser deposited on (001) yttria-stabilized ZrO2 (YSZ) substrates with different surface morphologies. The in-plane orientation of the films on smooth substrates was sensitive to the deposition conditions, often resulting in mixed orientations. However, a strongly dominating [110] YBCO//[110]YSZ orientation was obtained at a deposition temperature of 770°C. Films on substrates with surface steps, induced by depositing a homoepitaxial buffer layer or by thermally annealing the substrate, had a [110]YBCO//[100]YSZ orientation when deposited at the same temperature. It was concluded that the [110]YBCO//[100] YSZ orientation was promoted by a graphoepitaxial mechanism. Films prepared under identical conditions on smooth and stepped substrates grew with extended c axes on the former. It is proposed that the extension can be induced by disorder, invoked by a low oxygen pressure and a low density of adsorption sites. The disorder may be eliminated by either an increase of the oxygen pressure or an increase of the density of adsorption sites in the form of steps. The film microstructure influenced the microwave surface resistance, which was similar for films with one exclusive in-plane orientation and higher for films with mixed orientations. The films on the stepped surfaces had superior superconducting properties; inductive measurements gave a Tc onset of 88 K, a ΔT(90%-10%) c of 0.2 K, and the transport jc was 1.5×106 A/cm2 at 83 K, for films on substrates with homoepitaxial buffer layers.