Long-term ocean temperature trend and marine heatwaves

Marine heatwaves(MHWs)can cause irreversible damage to marine ecosystems and livelihoods.Appropriate MHW characterization remains difficult,because the choice of a sea surface temperature(SST)temporal baseline strongly influences MHW identification.Following a recent work suggesting that there should be a communicating baseline for long-term ocean temperature trends(LTT)and MHWs,we provided an effective and quantitative solution to calculate LTT and MHWs simultaneously by using the ensemble empirical mode decomposition(EEMD)method.The long-term nonlinear trend of SST obtained by EEMD shows superiority over the traditional linear trend in that the data extension does not alter prior results.The MHWs identified from the detrended SST data exhibited low sensitivity to the baseline choice,demonstrating the robustness of our method.We also derived the total heat exposure(THE)by combining LTT and MHWs.The THE was sensitive to the fixed-period baseline choice,with a response to increasing SST that depended on the onset time of a perpetual MHW state(identified MHW days equal to the year length).Subtropical areas,the Indian Ocean,and part of the Southern Ocean were most sensitive to the long-term global warming trend.

Physiological, Enzymatic and Molecular Changes of Acipenser schrencki Induced by Heat Exposure

[Objective] The paper was to understand the physiological, enzymatic and molecular changes of Acipenser schrencki induced by heat exposure. [Method] The effects of heat exposure on A. schrencki were investigated. The temperature was increased from(18± 0.5) ℃ by 0.08 ℃/min and respectively kept at(32±0.5) ℃ for 2, 4 and 6 h. The respiration rate, related biochemical indicators and heat shock protein 70(Hsp 70) mR-NA expression were investigated. [Result] At(32±0.5) ℃, the activities of total protein, albumin, globulin, urea nitrogen, ceatinine, malondialde-hyde, aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase fluctuated dramatically from 2 h to 6 h. Meanwhile, the respi-ration rate and Hsp 70 m RNA expression in heart, liver and spleen were significantly increased from 2 h to 6 h. In comparison, the lower respira-tion rate and tiny fluctuations in activities of biochemical indicators were consistent with the lower Hsp 70 expression. [Conclusion] During the process of heat stress, A. schrencki seems to be sensitive to such temperature, and manifests generally consistent gill breathing, biochemical indica-tors and Hsp70 gene expression, implying better heat tolerance.

Effects of glutamine pretreatment on learning and memory in heat-exposed rats

BACKGROUND： Glutamine （Gin） pretreatment can protect neural cells from injuries due to heat, ischemia, hypoxia, endotoxemia, and inflammatory factors. OBJECTIVE： To observe the effects of Gin pretreatment on learning and memory, survival time, and rectal temperature in heat-exposed rats. DESIGN, TIME AND SETTING： The present randomized grouping, neurobehavioral experiment was performed at the Laboratory of Department of Pharmacology, Basic School of Medicine, Wuhan University between March and September 2007. MATERIALS： Twenty-four healthy, Wistar rats were included in this study. SPX-160B biochemistry incubator （Shanghai Experimental Equipment Co., Ltd., China）, probe electronic thermometer （11000 type, Maikepai Science and Technology Co., Ltd., China）, Y-type maze box used in conjunction with MG-2 maze stimulator （Zhangjiagang Biomedical Instrument Factory, China）, L-Gln （Batch No. 061218, 5 g/bottle, prepared into 10% aqueous solution, Amresco Company, USA） were used. METHODS： Twenty-four rats were randomly and evenly divided into 3 groups： heat-exposed, Gln low-lose, and Gln high-dose. Following learning and memory testing with the Y-maze, rats in the heat-exposed group were subjected to heat injury （40.5-41.5 ℃） in a biochemistry incubator. Rectal temperature was measured every 5 minutes. Thirty-five minutes after heat exposure, rats were removed and placed in the Y-type maze to test learning and memory again. Subsequently, the rats were returned to the same environment of thermal stimulation until they died. Rat survival time was recorded. Subsequent to learning and memory testing, rats in the Gin low-dose and high-dose groups received an i.p. injection of Gin （0.4 g/kg and 0.8 g/kg, respectively）, and were exposed to heat injury. The remaining experimental procedures remained the same as for the heat-exposed group. MAIN OUTCOME MEASURES： Rat learning and memory, rectal temperature, and survival time in heat exposure environment. RESULTS： （1） In the Y-maze experiment, the frequency for the heat-exposed group rats to move 15 successive times through the maze without any mistakes was 13 times greater prior to heat exposure. Thirty-five minutes after heat exposure, rat learning and memory were significantly decreased, i.e., frequency was 9/15 correct trials （P 〈 0.01 ）. Following Gln pretreatment, rat learning and memory noticeably improved The frequency of Gln low-dose and high-dose rats maintained 13/15 correct trials, which was not different compared with before heat exposure （P 〉 0.05）. （2） The heat-exposed group required 14 minutes to reach the rectal temperature of 39.5℃. After 2 hours of Gln pretreatment, the Gln low-dose and high-dose groups needed 18 and 20 minutes, respectively （P 〈 0.05）. （3） Following 2 hours ofGln pretreatment, the survival time of the Gln low-dose and high-dose groups was 66 and 69 minutes, which was prolonged by 18.2% （P 〈 0.05） and 21.7% （P 〈 0.01）, respectively, compared with the heat-exposed group （54 minutes）. CONCLUSION： A 2-hour Gln pretreatment can noticeably improve learning and memory, delay ascending speed of body temperature, and prolong survival time in heat-exposed rats in a dose-dependent manner.

Specific Enthalpy Based Heat Stress Index for Indoor Environments without Radiation Effect

Over 100 human thermal indices have been developed to predict the combined thermal impact on the body.In principle,these indices based on energy thermal budget equations should not only be the most complex but also be the most accurate.However,the simple indices based on algebraic or statistical models[e.g.,the wet-bulb globe temperature(WBGT)]continue to be the most popular.A new heat stress index,the enthalpy dry-bulb temperature(EnD)for indoor environments is developed and validated in this study.The EnD index is unique in that it uses the air specific enthalpy,not the wet-bulb temperature,to measure the latent heat transfer from the skin to the surrounding environment.Theoretically,the EnD index can be treated as the equivalent temperature based on the convective heat transfer coefficient h_(c).Comparison is made between the EnD index and the widely used WBGT index based on the experimental data taken from three independent studies available in the scientific literature.The results show that the EnD index can reduce the overestimation of the dry-bulb air temperature and thus reduce heat stress in most cases,especially for hot and humid environments.It can be concluded that the EnD index has the potential to replace the WBGT index as the standard heat stress index in the future.

Climate change induced heat stress impact on workplace productivity in a net zero-carbon timber building towards the end of the century

Changing climate intensifies heat stress,resulting in a greater risk of workplace productivity decline in timber office buildings with low internal thermal mass.The impact of climate change induced heat exposure on indoor workplace productivity in timber office buildings has not been extensively researched.Therefore,further investigation to reduce the work capacity decline towards the end of the century is needed.Here,heat exposure in a net zero-carbon timber building near Brussels,Belgium,was evaluated using a reproducible comparative approach with different internal thermal mass levels.The analysis indicated that strategies with increased thermal mass were more effective in limiting the effects of heat exposure on workplace productivity.The medium and high thermal mass strategies reduced workplace productivity loss to 0.1%in the current,0.3%and 0.2%in the midfuture,and 4.9%and 3.9%for future scenarios.In comparison,baseline with low thermal mass yielded a decline of 2.3%,3.3%,and 8.2%.The variation in maximum and minimum wet-bulb globe temperatures were also lower for medium and high thermal mass strategies than for low thermal mass baseline.The study findings lead to the formulation of design guidelines,identification of research gaps,and recommendations for future work.

Physiological and subjective thermal responses to heat exposure in northern and southern Chinese people

When studying the thermal adaptation of building occupants,understanding the effects of different thermal experiences on adaptation is necessary,particularly for moderate and severe heat exposure.However,this area has seen limited research.Further,skin temperature,a common parameter for quantifying thermal sensation,may insufficiently reflect the automatic thermoregulation of the human body.This study investigates the effects of long-term heat exposure on the human body using multiple physiological and subjective indexes.Two heat exposure experiments were conducted on healthy male participants from northern and southern China.Participant responses,including skin temperature,heart rate,heart rate variability,blood volume pulse(BVP),subjective thermal comfort thermal sensation,thermal acceptability,and normalized high and low frequency values were collected and compared The results indicated that the subjective responses of northern and southern participants were not significantly different;however,the subjective physiological symptoms and self-reported discomfort of the latter were less than those of the former,indicating that the southern participants had superior heat tolerance.Additionally,the physiological responses of all the participants were largely similar.However,southern participants showed slightly higher normalized high frequency and BVP values,indicating that they have more active vagus nerves and better vasodilation.They also showed a wider acceptable temperature range and better acclimation to heat exposure.Notably,the mean skin temperature could not effectively predict thermal sensation during heat exposure;this was more accurately achieved using the rate of change of skin temperature.These findings suggest that long-term thermal experiences can affect building occupants’thermal adaptability.

Dehydrated patient without clinically evident cause:A case report

BACKGROUND Patients affected by cystic fibrosis can present with metabolic alkalosis such as Bartter's syndrome.In this case report we want to underline this differential diagnosis and we aimed focusing on the suspect of cystic fibrosis,also in case of a negative newborn screening.CASE SUMMARY In a hot August–with a mean environmental temperature of 36℃–an 8-mo-old female patient presented with severe dehydration complicated by hypokalemic metabolic alkalosis,in absence of fever,diarrhea and vomiting.Differential diagnosis between cystic fibrosis and tubulopathies causing metabolic alkalosis(Bartter's Syndrome)was considered.We started intravenous rehydration with subsequent improvement of clinical conditions and serum electrolytes normalization.We diagnosed a mild form of cystic fibrosis(heterozygous mutations:G126 D and F508 del in the cystic fibrosis transmembrane conductance regulator gene).The trigger factor of this condition had been heat exposure.CONCLUSION When facing a patient with hypokalemic metabolic alkalosis,cystic fibrosis presenting with Pseudo-Bartter's syndrome should be considered in the differential diagnosis,even if the newborn screening was negative.

Dynamic Assessment of Global Maize Exposure to Extremely High Temperatures

Exposure to extreme heat can severely harm crop growth and development,and it is essential to assess such exposure accurately to minimize risks to crop production.However,the actual distribution of crops and its changes have neither been examined in sufficient detail nor integrated into the assessments of exposure to ensure their accuracy.By examining the distribution of maize at a high resolution through species distribution modeling,we assessed the past and future exposure of maize to temperatures above 37℃worldwide.Such exposure is likely to be widespread and severe,mainly in the subtropics,and may even expand to the mid-latitudes to encompass some major maize-producing areas.Many areas at both high and low latitudes may become exposed for the first time in the next 20 years.By the 2050 s,the total area exposed could increase by up to 185%to 308.18 million ha,of which the area exposed for over 60 days may increase nearly sevenfold.The average length of exposure may increase by 69%to 27 days,and areas optimally suited to maize planting may see the fastest increase by up to 772%.Extreme heat can threaten global maize production severely,and measures to mitigate that threat and to adapt to it are urgently needed.

Effect of Temperature on Emergency Ambulance Call-Outs for Cardiovascular Causes:A Scoping Review

Climate change has increased interest in the effects of the thermal environment on cardiovascular health.Most studies have focused on mortality data.However,pre-hospital care data are better able to evaluate these effects,as they can register the full spectrum of the disease in real time.This scoping review aims to synthesize the epidemiological evidence regarding the effects of the thermal environment on cardiovascular morbidity in the pre-hospital setting,evaluated through ambulance calls.A staged literature search was performed using the PubMed database for the period between 1st January 2000 and 30th March 2023,using the MeSH terms“Weather”AND“Emergency Medical Services”.A total of 987 publications were identified that examined the correlation between the thermal environment and ambulance call-outs for cardiovascular causes.The studies were mostly ecological time series,with significant variability in the methodological aspects employed.An increase in the number of ambulance call-outs has been observed in association with low temperatures,both for overall cardiovascular pathologies and for certain pathological subtypes.For high temperatures,no effect has been observed in overall call-outs,although an increase has been observed during heat waves.The demand for ambulances for cardiac arrests is increased by both low and high temperatures and during heat waves.Ambulance call-outs for cardiovascular causes increase with low temperatures and heat waves,with no significant increase in the overall demand associated with high temperatures.Ambulance call-outs for cardiac arrests are the only subtype that is increased by high temperatures.

High temperature determines the ups and downs of small brown planthopper Laodelphax striatellus population

Small brown planthopper, Laodelphax striatellus （Fall6n） numbers usually drop sharply in the summer and revive quickly in the autumn. However, it is unclear whether and how the high temperature plays a role in this process. The effects of durations of heat exposure （33~C） on life-history traits were examined here. Exposure of adults for 1 day during the oviposition stage led to a very low survival of nymphs. The average longevity ofL. striatellus exposed for 1-31 days from oviposition was significantly longer than that of the control （27℃）. Short-term （1-5 days） heat exposure of the third instar nymphs did not significantly influence eclosion, but exposure of the fourth instar nymphs significantly increased eclosion. Lifespan from egg to adult was significantly lengthened when the third instar nymphs were exposed to heat for 2-15 days, or the fourth instar were exposed for 10 days. The preoviposition period was prolonged by heat exposure of the third or fourth instar nymphs. Short-term heat exposure of less than 3 days of the third or fourth instar nymphs did not restrict fecundity, but when the exposure duration exceeded 5 days the total eggs per female and hatchability decreased. Exposure to high temperature increased the brachypter rate of adults. In summary, low survival and slowing development under heat exposure resulted in population decline in the summer, and the relatively high fecundity and brachypter rate led to quick revival in autumn. Temperature in the summer determines the rise and fall in numbers ofL. striatellus.