Temperature Lag Effect Research Articles

Lag effect of ambient temperature on respiratory emergency department visits in Beijing: a time series and pooled analysis

BackgroundAlthough the association between ambient temperature and mortality of respiratory diseases was numerously documented, the association between various ambient temperature levels and respiratory emergency department (ED) visits has not been well studied. A recent investigation of the association between respiratory ED visits and various levels of ambient temperature was conducted in Beijing, China.MethodsDaily meteorological data, air pollution data, and respiratory ED visits data from 2017 to 2018 were collected in Beijing. The relationship between ambient temperature and respiratory ED visits was explored using a distributed lagged nonlinear model (DLNM). Then we performed subgroup analysis based on age and gender. Finally, meta-analysis was utilized to aggregate the total influence of ambient temperature on respiratory ED visits across China.ResultsThe single-day lag risk for extreme cold peaked at a relative risk (RR) of 1.048 [95% confidence interval (CI): 1.009, 1.088] at a lag of 21 days, with a long lag effect. As for the single-day lag risk for extreme hot, a short lag effect was shown at a lag of 7 days with an RR of 1.076 (95% CI: 1.038, 1.114). The cumulative lagged effects of both hot and cold effects peaked at lag 0–21 days, with a cumulative risk of the onset of 3.690 (95% CI: 2.133, 6.382) and 1.641 (95% CI: 1.284, 2.098), respectively, with stronger impact on the hot. Additionally, the elderly were more sensitive to ambient temperature. The males were more susceptible to hot weather than the females. A longer cold temperature lag effect was found in females. Compared with the meta-analysis, a pooled effect of ambient temperature was consistent in general. In the subgroup analysis, a significant difference was found by gender.ConclusionsTemperature level, age-specific, and gender-specific effects between ambient temperature and the number of ED visits provide information on early warning measures for the prevention and control of respiratory diseases.

The impact of high temperatures on bird responses to alarm calls

Given the current pace of climate change, high temperature events will become increasingly frequent in many parts of the world. Predicting how high temperatures will impact the behavior of songbirds—highly sensitive to temperature change due to their tendency to be small in size, and to have high metabolic rates and diurnal habits—is therefore crucial and urgent. However, the behavioral impacts of high temperatures on acoustic communication in birds have rarely been studied. Responsiveness to antipredator signals is an important behavior to consider because failure to detect such signals could be lethal. We investigated whether, in great tits (Parus major), high temperatures would affect behavioral responses to playback of conspecific mobbing calls. We found a significant lag effect of temperature on how closely great tits would approach the playback speaker, with birds approaching less closely at higher temperatures. Further, we found that the emission of mobbing calls by great tits was affected by the current ambient temperature, with birds calling less at higher temperatures. The results suggest that at high temperatures, great tits change their tactic from active defense to less active response. High temperatures can thus induce behavioral shifts in great tits. In the current context of increasing average temperatures, such effect of temperature on response to vital indicators such as antipredator signals could impact survival when inducing greater risk of depredation.Significance statementClimate change is causing heatwaves to increase in number and intensity. High temperatures can reduce the ability of birds to respond to vocalizations. Here, we test if high temperatures affect the ability of great tits (Parus major) to respond to conspecific mobbing calls—these calls generally serve to mob a predator and to recruit conspecifics and heterospecifics to join the caller. At higher temperatures, great tits produce fewer mobbing vocalizations and approach the loudspeaker broadcasting mobbing calls less often.

Effects of temperature on incidence of bacillary dysentery in a temperate continental arid climate city in northwest China.

The effect of ambient temperature on health continues to draw more and more attention with the global warming. Bacillary dysentery (BD) is a major global environmental health issue and affected by temperature and other environmental variables. In the current study, we evaluated the effect of temperature on the incidence of BD from January 1st, 2008 to December 31st, 2011 in Jiayuguan, a temperate continental arid climate city in the Hexi Corridor of northwest China. A distributed lag non-linear model (DLNM) was performed to evaluate the lag effect of temperature on BD up to 30 days. Results showed the risk of BD increased with temperature significantly, especially after 8°C. The maximum risk of BD was observed at extreme high temperature (29°C). The effect of temperature on BD risk was significantly divided into short-term effect at lag 5 days and long-term effect at lag 30 days. Age ≤ 15 years were most affected by high temperature. The maximum cumulative risk for lag 30 days (25.8, 95% CIs: 11.8-50.1) was observed at 29°C. Age ≤ 15 years and females showed short-term effect at lag 5 days and long-term effect at lag 30 days, while age > 15 years and males showed acute short-term effect at lag 0 and light long-term effect at lag 16 days.

Experimental and Numerical Investigations of Structural Performance of Slab Track under Hygrothermal Environment

The coupled heat and moisture actions could easily cause deformation, cracking and corrosion problems in the slab ballastless track under operational conditions via China Railway Track System (CRTS) Ⅱ. In this paper, two one-quarter-scaled models of CRTS Ⅱ slab ballastless track under hygro-thermal environment were tested in a testing chamber, respectively. To study the effect of constrained conditions on the structural performance of track structure, temperature distribution, stress and displacement of two scaled models with constrained and free boundary conditions were also compared. Then, the temperature and stress field of the track structure was investigated by establishing a finite-element model. The results showed that the temperature transfer between layers has a temperature-lag effect. The positive and negative temperature gradients between the lower part of the track slab and the cement asphalt (CA) mortar layer of the constrained specimen are smaller than those of the free specimen. The longitudinal displacement of the track slab for the free specimen is significantly affected under the hygro-thermal environment and the longitudinal displacement of the concrete base and the track slab forms a displacement difference. Numerical-analysis results showed that the bottom of the concrete base is prone to produce a high-temperature core and that the temperature inside the track structure forms an agglomeration effect. KEYWORDS: Slab track, Hygro-thermal environment, Structural performance, Scale model, Finiteelement model.

Climate-driven scrub typhus incidence dynamics in South China: A time-series study

Background: Scrub typhus (ST) is a climate-sensitive infectious disease. However, the nonlinear relationship between important meteorological factors and ST incidence is not clear. The present study identified the quantitative relationship between ST incidence and meteorological factors in southern China.Methods: The weekly number of ST cases and simultaneous meteorological variables in central Guangdong Province from 2006 to 2018 were obtained from the National Notifiable Infectious Disease Reporting Information System and the Meteorological Data Sharing Service System, respectively. A quasi-Poisson generalized additive model combined with a distributed lag nonlinear model (DLNM) was constructed to analyze the lag-exposure-response relationship between meteorological factors and the incidence of ST.Results: A total of 18,415 ST cases were reported in the study area. The estimated effects of meteorological factors on ST incidence were nonlinear and exhibited obvious lag characteristics. A J-shaped nonlinear association was identified between weekly mean temperature and ST incidence. A reversed U-shaped nonlinear association was noted between weekly mean relative humidity and ST incidence. The risk of ST incidence increased when the temperature ranged from 24°C to 28°C, the relative humidity was between 78% and 82%, or the precipitation was between 50 mm and 150 mm, using the medians as references. For high temperatures (75th percentile of temperature), the highest relative risk (RR) was 1.18 (95% CI: 1.10–1.27), with a lag effect that lasted 5 weeks. High relative humidity (75th percentile of relative humidity) and high precipitation (75th percentile of precipitation) could also increase the risk of ST.Conclusion: This study demonstrated the nonlinear relationship and the significant positive lag effects of temperature, relative humidity, and precipitation on the incidence of ST. Between particular thresholds, temperature, humidity, and levels of precipitation increased the risk of ST. These findings suggest that relevant government departments should address climate change and develop a meteorological conditions-depend strategy for ST prevention and control.

Lag Effect of Temperature and Humidity on COVID-19 Cases in 11 Chinese Cities

The global transmission of COVID-19 has caused considerable health burdens, and epidemiological studies have proven that temperature and humidity play an important role in the transmission of infectious respiratory diseases. This effect may not be immediate and can be delayed by days to weeks. In this study, the comprehensive effect of temperature and humidity on COVID-19 was evaluated using the discomfort index (DI). We analyzed the lag effect of the DI on COVID-19 from 21 January to 29 February 2020 in 11 Chinese cities by designing a generalized additive model (GAM). We classified the 11 Chinese cities into southern cities and northern cities to compare the potential effects in these two types of cities. The results reveal that the DI had the same negative correlation and different lag effects on daily COVID-19 cases. There was a significant negative correlation between the DI and daily COVID-19 cases (p < 0.05), except in Wuhan. The lag effect was stronger in the cities located further north. In northern cities, each unit decrease in the DI increased the COVID-19 risk from 7 to 13 lag days. In southern China, each unit decrease in the DI increased the COVID-19 risk from 0 to 7 lag days, especially in Shanghai, Guangzhou, and Shenzhen.

Responses of subalpine meadow to climatic factors and the time lag effects in Wuyi Mountains from 2000 to 2019

Subalpine meadow is extremely sensitive to climate change. Few studies, however, focused on the responses of subalpine meadow to climatic factors in subtropical regions. It is still a challenge to extract the biophysical parameters from optical remote sensing imagery during the growing season. Based on the normalized difference vegetation index (NDVI) time series dataset from the MOD13Q1 vegetation index products and meteorological data, we analyzed the changes of vegetation growth of subalpine meadow at Huanggang Mountain in the top of Wuyishan National Park from 2000 to 2019, its responses to climate factors and the time lag effects. The results showed that NDVI in summer increased insignificantly during 2000-2019, and that NDVI in the growing season, spring, and autumn increased significantly. The enhancement of NDVI was mainly contributed by the increasing temperature (0.026 ℃·a-1) from 2000 to 2019. The increasing temperature in spring and autumn influenced meadow growth more than that in summer and growing season. NDVI of the growing season in subalpine meadow was sensitive to precipitation,indicating that the growth of subalpine meadow was strongly affected by precipitation even in the subtropical region with sufficient precipitation. Temperature and precipitation in different growth periods had different time lag effects on the NDVI of subalpine meadowo. The time lag effects of temperature on subalpine meadow were 0-1 month, and that of precipitation were 2-3 month.

Analysis of the time-lag effects of climate factors on grassland productivity in Inner Mongolia

Understanding the time-lag responses of grassland productivity to climate change is crucial for revealing grassland ecosystem behavior, predicting future grassland productivity, and guiding animal husbandry practices. This study developed a new analytical method to examine lag effects of climate change by integrating three techniques of time-lag effect analysis, time-lag accumulation computation and partial least-square regression. Net primary productivity (NPP) of vegetation was used as an evaluation indicator for grassland productivity. Based on the monthly scale of the continuous growing season (with a delay of 0–3 months), the effects of temperature and precipitation on grassland productivity of Inner Mongolia were assessed. The results showed that the correlation coefficient between the estimated NPP based on the CASA (Carnegie-Ames-Stanford Approach) model and the MOD17A3-NPP data reached 0.949. Compared with the estimation using CASA, the proportion of correlation coefficients for NPP derived from the PLS regression against temperature or precipitation was over 90% at P < 0.01. The lag effect of temperature and precipitation on grassland productivity was approximately 3 months. The contribution rates over 0–3 months gradually decreased from positive to negative. Over 89% of the study areas, the temperature and precipitation of the current month had the most considerable contribution to NPP. In the remaining areas, the strongest lag effect occurred in the second or third month.

Meteorological factors and related lag effects on scrub typhus in southwestern Yunnan

Objective: To analyze the influence and related lag effects of meteorological factors on scrub typhus (ST) in southwestern Yunnan, to provide a reference for the corresponding prevention and treatment measures. Methods: Data on ST and meteorology in Yunnan province from 2007 to 2018 were collected. A distributed lag nonlinear model was conducted to study the cumulative lag effects of temperature, relative humidity, and rainfall on ST. Results: From 2007-2018, a total of 19 975 ST cases were reported in southwestern Yunnan. Weekly mean temperature, mean relative humidity, and the risk of ST all showed J-shaped curves. The cumulative risk of ST increased with mean temperature >23 ℃, mean relative humidity >80%, and cumulative rainfall between 20 and 60 mm or over 100 mm, weekly. Taking the median value as the reference, higher temperature (22.27 ℃, 23.45 ℃), relative humidity (80.14%, 84.38%) and rainfall (37.17 mm, 74.42 mm) all increased the risk of disease while lower temperature (11.22 ℃,14.83 ℃), relative humidity (53.18%,65.36%) and rainfall (0.00 mm,0.55 mm) showed opposite effects. The temperature-lag effect lasted for 10 and 16 weeks, respectively, with ST's risk the highest during the week of exposure. Humidity-lag effects usually last for 10 and 17 weeks. The lag effect of rainfall lasted for 25 weeks, while the disease's risk was the highest in the 4th week. Conclusion: Factors as temperature, relative humidity, and precipitation showed nonlinear and lag effects on ST. High temperature, high relative humidity, and an appropriate amount of rainfalls increase the risk of ST. The authorities of public health should implement effective prevention and control measures according to meteorological conditions.

Effects and interaction of meteorological factors on hemorrhagic fever with renal syndrome incidence in Huludao City, northeastern China, 2007-2018.

BackgroundHemorrhagic fever with renal syndrome (HFRS), a rodent-borne disease, is a severe public health threat. Previous studies have discovered the influence of meteorological factors on HFRS incidence, while few studies have concentrated on the stratified analysis of delayed effects and interaction effects of meteorological factors on HFRS.ObjectiveHuludao City is a representative area in north China that suffers from HFRS with primary transmission by Rattus norvegicus. This study aimed to evaluate the climate factors of lag, interaction, and stratified effects of meteorological factors on HFRS incidence in Huludao City.MethodsOur researchers collected meteorological data and epidemiological data of HFRS cases in Huludao City during 2007–2018. First, a distributed lag nonlinear model (DLNM) for a maximum lag of 16 weeks was developed to assess the respective lag effect of temperature, precipitation, and humidity on HFRS incidence. We then constructed a generalized additive model (GAM) to explore the interaction effect between temperature and the other two meteorological factors on HFRS incidence and the stratified effect of meteorological factors.ResultsDuring the study period, 2751 cases of HFRS were reported in Huludao City. The incidence of HFRS showed a seasonal trend and peak times from February to May. Using the median WAT, median WTP, and median WARH as the reference, the results of DLNM showed that extremely high temperature (97.5th percentile of WAT) had significant associations with HFRS at lag week 15 (RR = 1.68, 95% CI: 1.04–2.74) and lag week 16 (RR = 2.80, 95% CI: 1.31–5.95). Under the extremely low temperature (2.5th percentile of WAT), the RRs of HFRS infection were significant at lag week 5 (RR = 1.28, 95% CI: 1.01–1.67) and lag 6 weeks (RR = 1.24, 95% CI: 1.01–1.57). The RRs of relative humidity were statistically significant at lag week 10 (RR = 1.19, 95% CI: 1.00–1.43) and lag week 11 (RR = 1.24, 95% CI: 1.02–1.50) under extremely high relative humidity (97.5th percentile of WARH); however, no statistically significance was observed under extremely low relative humidity (2.5th percentile of WARH). The RRs were significantly high when WAT was -10 degrees Celsius (RR = 1.34, 95% CI: 1.02–1.76), -9 degrees Celsius (1.37, 95% CI: 1.04–1.79), and -8 degrees Celsius (RR = 1.34, 95% CI: 1.03–1.75) at lag week 5 and more than 23 degrees Celsius after 15 weeks. Interaction and stratified analyses showed that the risk of HFRS infection reached its highest when both temperature and precipitation were at a high level.ConclusionsOur study indicates that meteorological factors, including temperature and humidity, have delayed effects on the occurrence of HFRS in the study area, and the effect of temperature can be modified by humidity and precipitation. Public health professionals should pay more attention to HFRS control when the weather conditions of high temperature with more substantial precipitation and 15 weeks after the temperature is higher than 23 degrees Celsius.

Epidemic characteristics of hand, foot and mouth disease (HFMD) and the lag effect of average daily temperature on the epidemic of HFMD in Beijing

Objective: To analyze the epidemic characteristics of hand, foot and mouth disease (HFMD) in Beijing and explore the short-term lag effect of daily average temperature on HFMD. Methods: The incidence data and meteorological data of HFMD were collected from Xicheng District, Chaoyang District, and Changping District of Beijing between January 2009 and December 2018. The dose-response relationship and short-term lag effect of temperature and HFMD incidence were explored by the distributed lag non-linear model (DNLM). Results: From 2009 to 2018, a total of 97 210 cases of HFMD were confirmed in Xicheng District, Chaoyang District, and Changping District of Beijing. The incidence rate of HFMD in Xicheng district was 71.83/100 000, which was the lowest in three districts. The total annual average incidence was 146.89/100 000 in the three districts. The cases were concentrated from May to July, with a small peak in October to November. The ratio of male to female was 1.49∶1, and the median age of the patients was 3.08 (1.89, 4.39) years old, which showed a decreasing trend in children under 6 years old (Z=-30.11, P<0.01). The DNLM showed that the cumulative relative risk (RR) curve had a bimodal distribution, with RR of 1.36 (95%CI: 1.05-1.76) and 1.35 (95%CI: 1.10-1.66), and the peak values appeared at 4 ℃ and 26 ℃, respectively. Conclusions: The incidence rate of HFMD in Xicheng was the lowest in three districts of Beijing. In addition, the incidence of HFMD is seasonal, and the incidence is higher in spring and summer than that in autumn and winter. Daily average temperature had a lag effect on HFMD, which was different between high temperature and low temperature.

Impact of extreme temperatures on ambulance dispatches in London, UK

BackgroundAssociations between extreme temperatures and health outcomes, such as mortality and morbidity, are often observed. However, relatively little research has investigated the role of extreme temperatures upon ambulance dispatches. MethodsA time series analysis using London Ambulance Service (LAS) incident data (2010–2014), consisting of 5,252,375 dispatches was conducted. A generalized linear model (GLM) with a quasi-likelihood Poisson regression was applied to analyse the associations between ambulance dispatches and temperature. The 99th (22.8°C) and 1st (0.0°C) percentiles of temperature were defined as extreme high and low temperature. Fourteen categories of ambulance dispatches were investigated, grouped into ‘respiratory’ (asthma, dyspnoea, respiratory chest infection, respiratory arrest and chronic obstructive pulmonary disease), ‘cardiovascular’ (cardiac arrest, chest pain, cardiac chest pain RCI, cardiac arrhythmia and other cardiac problems) and ‘other’ non-cardiorespiratory (dizzy, alcohol related, vomiting and ‘generally unwell’) categories. The effects of long-term trends, seasonality, day of the week, public holidays and air pollution were controlled for in the GLM. The lag effect of temperature was also investigated. The threshold temperatures for each category were identified and a distributed lag non-linear model (DLNM) was reported using relative risk (RR) values at 95% confidence intervals. ResultsMany dispatch categories show significant associations with extreme temperature. Total calls from 999 dispatches and ‘generally unwell’ dispatch category show significant RRs at both low and high temperatures. Most respiratory categories (asthma, dyspnoea and RCI) have significant RRs at low temperatures represented by with estimated RRs ranging from 1.392 (95%CI: 1.161–1.699) for asthma to 2.075 (95%CI: 1.673–2.574) for RCI. The RRs for all other non-cardiorespiratory dispatches were often significant for high temperatures ranging from 1.280 (95% CI: 1.128–1.454) for ‘generally unwell’ to 1.985 (95%CI: 1.422–2.773) for alcohol-related. For the cardiovascular group, only chest pain dispatches reported a significant RR at high temperatures. ConclusionsAmbulance dispatches can be associated with extreme temperatures, dependent on the dispatch category. It is recommended that meteorological factors are factored into ambulance forecast models and warning systems, allowing for improvements in ambulance and general health service efficiency.

Analysis on the lag effect of temperature - sea ice concentration in key Arctic Straits

Analysis on the lag effect of temperature - sea ice concentration in key Arctic Straits

Inverse effects of recent warming on trees growing at the low and high altitudes of the Dabie Mountains, subtropical China

Understanding how tree rings of different species at different elevations respond to climate, and whether their relationship is stable over time is crucial not only for credible palaeoclimatic reconstructions, but also for better awareness of forest growth dynamics and therefore making scientific management decisions against a background of global warming. In this work, six tree-ring chronologies of Pinus taiwanensis at three sites from 800 to 1550 m above sea level (asl), and Pinus massoniana at three sites from 500 to 650 m asl were developed in the Dabie Mountains (DBS), subtropical China. In recent decades, only P. taiwanensis at 1550 m asl showed a positive growth-trend. Both P. taiwanensis at 800 m asl and three low-altitude P. massoniana at 500–650 m asl showed negative growth trends. Climate-growth relationship analyses revealed that 1) temperature was the dominant climatic factor that controlled tree-ring growth in DBS. It exerted most influence on trees growing at the lower and upper limit, than for trees growing at altitudes from 650 to 1450 m asl. Only precipitation in October positively influenced tree growth of P. massoniana at all three sites and P. taiwanensis at 800 m asl; 2) There was a shift in temperature’s impact on trees, that was from significantly negative relationship at the four lower altitudes, mainly for the current growing-season, to significantly positive relationship in previous February–July period at the highest altitude. The higher the altitude, the more significant the lag effect of temperature on trees; 3) The influence of temperature on tree growth at most altitudes were variable over time. The positive influence of temperature on trees at 1550 and 1450 m asl was comparatively stable during the early period of instrumental records. It strengthened evidently since the early 1990s, which is coincidental with the timing of the evident temperature increase in DBS. On the contrary, the negative impacts of temperature on tree growth at 800, 650 and 500 m asl had weakened since the early 1990s. Besides the increase of water use efficiency of trees, we speculated that the increasing influence of precipitation in May and July weakened the relationship between temperature and tree rings at low altitudes. This work points out that the upper and lower limits of forest in DBS offer the preferred locations for future sampling in climate reconstruction, but the stability of tree growth and climate over time should be considered. Moreover, forest management should give priority to altitude factors, in addition to tree species representation.

Lag effect and influencing factors of temperature on other infectious diarrhea in Zhejiang province

Objective: To study the lag effect of temperature and the source of heterogeneity on other infectious diarrhea (OID) in Zhejiang province, so as to identify related vulnerable populations at risk. Methods: Data on OID and meteorology in Zhejiang province from 2014 to 2016 were collected. A two-stage model was conducted, including: 1) using the distributed lag non-linear model to estimate the city-specific lag effect of temperature on OID, 2) applying the multivariate Meta- analysis to pool the estimated city-specific effect, 3) using the multivariate Meta-regression to explore the sources of heterogeneity. Results: There were 301 593 cases of OID in Zhejiang province during the study period. At the provincial level, temperature that corresponding to the lowest risk of OID was 16.7 ℃, and the temperature corresponding to the highest risk was 6.2℃ (RR=2.298, 95%CI: 1.527- 3.459). 16.7 ℃ was recognized as the reference temperature. P(5) and P(95) of the average daily temperature represented low and high temperature respectively. When the temperature was cold, the risk was delayed by 2 days, with the highest risk found on the 5(th) day (RR=1.057, 95%CI: 1.030-1.084) before decreasing to the 23(rd) day. When the temperature got hot, the risk of OID occurred on the first day (RR=1.081, 95%CI: 1.045-1.118) and gradually decreasing to the 8(th) day. Differences on heterogeneous sources related to the risks of OID in different regions, presented on urban latitude and the rate of ageing in the population. Conclusions: Both high or low temperature could increase the risk of OID, with a lag effect noticed. Prevention program on OID should be focusing on populations living in the high latitude and the elderly population at the low temperature areas.

The effects of temperature on short-term mortality risk in Kuwait: A time-series analysis

BackgroundIn light of climate change, health risks are expected to be exacerbated by extreme temperatures. Many studies showed that high and low ambient temperatures are associated with increased short-term mortality risk, but little is known about these risks in Kuwait and the Gulf Region. ObjectiveTo examine the dose-response relationship between 24-h average ambient temperatures and daily mortality risk in Kuwait. MethodsWe gathered mortality and meteorological data from 2010 to 2016 in Kuwait. We did a time-series analysis using a negative binomial distribution, and studied the lag effects of temperature with distributed lag non-linear models. ResultsA total of 33,574 all-cause non-accidental deaths were analyzed. The relationship was shown to be non-linear. Overall relative risks of death comparing the 1st percentile (10.9 °C) and the 99th percentile (42.7 °C) to the optimum temperature were 1.67 (1.02–2.73), and 1.65 (1.09–2.48), respectively. Cold effects persisted for 9 days, while the effects of hot temperatures were the highest at lag 0 and only persisted for a week. Adjusting for PM10 and ozone did not change the temperature-mortality estimates. ConclusionOur findings show evidence that there is a statistically significant positive association between temperature extremes and mortality in Kuwait. The evidence has significant implications in assessing climate vulnerability and provides insight into environmental challenges in an inherently hot and arid region.

Temperature lag effect on TL glow peaks: Corrections on kinetic parameters

Analyses on TL glow curves recorded with various heating rates for some ternary and quaternary crystals were accomplished using peak maximum temperatures (Tmax) which are experimentally obtained and corrected according to temperature lag effect proposed by Kitis and Tuyn. Curve fitting, initial rise, peak shape and variable heating rate methods were applied to experimental and corrected TL peaks. In spite of the fact that heating rate does not affect activation energy of a TL peak, analyses performed on the experimentally obtained TL curves resulted in an increment of the activation energy with increasing heating rate. However, as the corrected TL data were used for the analyses, the activation energy values of each TL peak recorded with different heating rate were in good agreement with each other. The detailed analyses on studied samples were given in the present paper.

Heating rate properties and kinetic parameters of thermoluminescence glow curves of La-doped zinc borate

The aim of this study is to evaluate the effect of different heating rates (HRs) on low and high temperature thermoluminescence (TL) glow-peaks, reusability properties, and the kinetic parameters (activation energy (E), frequency factor (s) and order of kinetics (b)) of 1%, 4% and 10% La-doped ZnB2O4 phosphors. All La-doped ZnB2O4 phosphors have two characteristic TL peaks at around 80–85 °C and 150–160 °C. The experimental results show that the TL glow-peak temperatures (TM) shift to higher temperatures for all doped materials as the HRs increase because of the temperature lag effect. The maximum peak intensity (IM) decreases for the first peak of 1% doped, remains roughly constant for second peak of 1% and both peaks of 4% doped, and increases for both peaks of 10% La-doped ZnB2O4 samples as the HRs increases. Differences between the intensities of various amounts of La-doped phosphors were explained with anomalous HR phenomenon except the first peak of 1% La-doped ZnB2O4 which was clarified by thermal quenching effect. In this study, the temperature dependence of the recombination rate of released carriers during the heating process by increasing the doping concentration of La might explain the peaks of the glow curves, which shows an unexpected behavior with the increasing HR values. In addition, the calculated E values of all doped phosphors were found similar in the range of 0.62 – 1.03 eV for 1%, 0.65 – 1.15 eV for 4%, and 0.69 – 1.01 eV for 10% La-doped phosphors. However, s values were found slightly different related to the dopant amount. Furthermore, different dopant amounts indicate the similar and reasonable properties for the repeated cycles of 5 Gy with the same readout conditions.

Kinetic characterization of the first peak of natural fluorite from low dose β-irradiation

The low temperature peak (PI) of natural fluorite which occurs at 94oC at the heating rate of β = 1 Cs-1exhibits complexity both in terms of shape and position as the absorbed dose is varied. The short lifetime of this peak makes it a good case for testing the existing thermoluminescence kinetic models. In this paper, the kinetic parameters of PI, namely the activation energy, EA , the frequency factor, S, and the order of kinetics, b, have been evaluated using general order kinetics. Fluorite samples were irradiated with a low dose-rate (40 μGys-1 ) β- irradiation source to a test dose of 1.2 mGy and the heating rates of β = 1,3 and 5o Cs were considered, in order to minimize the effect of temperature lag. The role of thermal quenching (W) was investigated by evaluating the activation energy using the initial rise (IR) method for each of the heating rates. The obtained values of kinetic parameters are EA = (1.31 ± 0.06) eV and S = (8.34 ± 1.00) × 1016 s-1 while values of b ranging from above 1.0 up to 1.4 were in good agreement. The value of W = (0.30 ± 0.04) eV was obtained for the thermal quenching function and its contribution was found to be most significant at the heating rate of β = 5so C s-1 .Keywords: low-dose β-irradiation, first peak of natural fluorite, general-order kinetics, thermal quenching function, peak lifetime.

Ambient Temperature and Stroke Risk: Evidence Supporting a Short-Term Effect at a Population Level From Acute Environmental Exposures.

These are times of increasing concern about the impact on global health of climate change and political turmoil on how to tackle global warming.1,2 Global warming produces not only hotter summers and more frequent episodes of heat waves but also colder winters, especially in more temperate zones, with populations not accustomed to these unusual weather conditions.3 These changes affect human physiology and have the potential of acutely influencing the occurrence of cardiovascular diseases, such as stroke, but the evidence has been until recently conflicting, a great number of which initially came from observational studies on season rather than temperature.4–6 In this review, we examine the current evidence on the association of acute ambient temperature changes and the risk of stroke morbidity and mortality by pathological subtypes. Ambient temperature is defined as the temperature of the surrounding air, and as such, it is modified by humidity, so that in many studies, the exposure is a combination of temperature and humidity level or dew point temperature and may be expressed as thermo-hydrological index when humidity is controlled for.7 Ambient temperature is usually measured at or near airport monitoring stations and thus may introduce bias on real indoor exposures and in urban to rural comparison.8 The effect of ambient temperature on stroke has been studied in relation to daily or monthly mean, maximum, and minimum temperatures and temperature change or variation. It is suggested that mean ambient temperature is the best exposure measure because it can represent the exposure throughout the whole day and night and provide more easily interpretable results, although some authors state that all measurements of temperature have the same predictive ability on health outcomes.9 Two methodological issues have been given special attention: temperature lag effect (exposure response association) and …