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Purpose: To assess whether heat trapped under ophthalmic drapes is responsible for patient reports of being hot during cataract surgery using local anesthesia., Setting: Departments of Anaesthesia and Intensive Care Medicine and of Ophthalmology and Optometry, Innsbruck University Hospital, Innsbruck, Austria., Methods: In a prospective, randomized, single-blind study, the temperature in the ambient air under 2 types of paper drapes (Group A: Barrier Ophthalmology Drape, Johnson & Johnson; Group B: Steri Drape 1062, 3M) and a plastic drape (Group C: cotton drape + Steri Drape 1024, 3M) was measured for 25 minutes in 60 patients having cataract surgery under local anesthesia., Results: Three minutes after the patient's head was draped, the mean temperature under the drape began to increase significantly: Group A, 25.7 degrees C +/- 0.3 degree C (SD) to 29.17 degrees C +/- 0.9 degree C (P < or = .001); Group B, 25.87 degrees C +/- 0.4 degree C to 29.41 degrees C +/- 0.9 degree C (P < or = .001); Group C, 25.8 degrees C +/- 0.35 degree C to 29.4 degrees C +/- 0.6 degree C (P < or = .001). It continued to increase in all groups as the operation continued. No significant differences in temperature were observed among the 3 drape types studied. Subjective thermal discomfort was reported by 35% to 40% of patients., Conclusion: Paper drapes did not cause less heat from being trapped than the plastic drape. Trapped heat may impair the comfort of patients having eye surgery under local anesthesia.

Paper wasps, like Polistes dominula, are considered as primitively eusocial. Hence, they are often used as model species for studies about the evolution of eusociality and dominance hierarchies. However, our knowledge about basic physiological processes in these wasps remains limited. In particular, the thermoregulation of individual wasps in their natural habitat has not yet been investigated in detail. We conducted a comprehensive field study to test their ability to respond to external hazards with elevated thorax temperatures. We presented artificial threats by applying smoke or carbon dioxide simulating fire and predator attacks, respectively, and monitored the thorax temperature of wasps on the nest using infrared thermography. We found that P. dominula workers recognized smoke and CO2 and reacted almost instantaneously and simultaneously with an increase of their thorax temperature. The maximal thorax temperature was reached about 65 s after the application of both stressors, but subsequently, the wasps showed a different behaviour pattern. No rise of the thorax temperature was detectable after an air blast was applied or in wasps resting on the nest. These observations provide evidence that P. dominula is able to heat up its thorax and that thermoregulation is employed in escape and defence reactions. Additionally, we investigated the thorax temperatures of queens during dominance battles. We found that the thorax temperature of the dominant queens rose up to 5 °C compared to that of subordinate queens that attacked the former, suggesting that the dominant queen defends herself as well as her nest.

Introduction: Written examinations are integral component of students' assessments at formative and summative level. There is no blueprint of question paper available for the new curriculum in Bachelor of Medicine and Bachelor of Surgery (MBBS) Physiology curriculum which may lead to variations in question paper setting. This lack of consistency in question papers affects the preparedness and performance of students. Aim: To prepare the blueprint of MBBS Physiology Competency Based Medical Education (CBME) curriculum and to do content validity by comparing with Preliminary Examination (PE) and University Examination (UE). Materials and Methods: This was a descriptive study conducted over a period of six months from July 2020 till December 2020. The study was conducted in Armed Forces Medical College, Pune. There are 15 topics and 140 outcomes for Physiology MBBS course as per new CBME curriculum is divided into paper I and II according to Maharashtra University of Health Sciences (MUHS) syllabus. The main topics in each paper were further subdivided into subtopics for preparing learning objectives. Marks were allotted to each system taking into consideration optimum marks 97 for subjective with included options and 20 marks Multiple Choice Questions (MCQs). The papers of UE and PE conducted with new format were analysed for content validity. Results: The blueprint of paper I (subjective) shows marks allotted for General Physiology 12, Haematology 13, Respiratory System (RS) 15, Cardiovascular (CVS) 17, Exercise 05, Renal system 15, Gastrointestinal System (GIT) 12, Lifestyle Aging and Meditation 03 and Attitude, Ethics and Communication. (AETCOM) 05 marks. The blueprint of paper II (subjective) shows marks for the Nerve-Muscle 16, Central Nervous System (CNS) 25, Special senses 14, endocrine system are 18, reproductive system 15, and temperature 09. MCQs were also allotted proportionate marks for each topic. Content analysis of papers showed exercise Physiology and body temperature regulation were not assessed in UE. Conclusion: There was disproportionate representation of topics in formative and summative examinations in absence of blueprint. The blueprint should be an integral part of assessments. [ABSTRACT FROM AUTHOR]

In this, the second of four historical reviews on human thermoregulation during exercise, we examine the research techniques developed by our forebears. We emphasise calorimetry and thermometry, and measurements of vasomotor and sudomotor function. Since its first human use (1899), direct calorimetry has provided the foundation for modern respirometric methods for quantifying metabolic rate, and remains the most precise index of whole-body heat exchange and storage. Its alternative, biophysical modelling, relies upon many, often dubious assumptions. Thermometry, used for >300 y to assess deep-body temperatures, provides only an instantaneous snapshot of the thermal status of tissues in contact with any thermometer. Seemingly unbeknownst to some, thermal time delays at some surrogate sites preclude valid measurements during non-steady state conditions. To assess cutaneous blood flow, immersion plethysmography was introduced (1875), followed by strain-gauge plethysmography (1949) and then laser-Doppler velocimetry (1964). Those techniques allow only local flow measurements, which may not reflect whole-body blood flows. Sudomotor function has been estimated from body-mass losses since the 1600s, but using mass losses to assess evaporation rates requires precise measures of non-evaporated sweat, which are rarely obtained. Hygrometric methods provide data for local sweat rates, but not local evaporation rates, and most local sweat rates cannot be extrapolated to reflect whole-body sweating. The objective of these methodological overviews and critiques is to provide a deeper understanding of how modern measurement techniques were developed, their underlying assumptions, and the strengths and weaknesses of the measurements used for humans exercising and working in thermally challenging conditions., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: To determine the effect of taurine supplementation on sweating and core temperature responses, including the transition from compensable to uncompensable heat stress, during prolonged low-intensity exercise of a fixed-heat production (~ 200W/m 2 ) in hot conditions (37.5 °C), at both fixed and incremental vapour-pressure., Methods: Fifteen females (n = 3) and males (n = 12; 27 ± 5 years, 78 ± 9 kg, V ˙ O 2max 50.3 ± 7.8 mL/kg/min), completed a treadmill walking protocol (~ 200W/m 2 heat production [Ḣ prod ]) in the heat (37.5 ± 0.1 °C) at fixed-(16-mmHg) and ramped-humidity (∆1.5-mmHg/5-min) following 1 week of oral taurine supplementation (50 mg/kg/bm) or placebo, in a double-blind, randomised, cross-over design. Participants were assessed for whole-body sweat loss (WBSL), local sweat rate (LSR), sweat gland activation (SGA), core temperature (T core ), breakpoint of compensability (P crit ) and calorimetric heat transfer components. Plasma volume and plasma taurine concentrations were established through pre- and post-trial blood samples., Results: Taurine supplementation increased WBSL by 26.6% and 5.1% (p = 0.035), LSR by 15.5% and 7.8% (p = 0.013), SGA (1 × 1 cm) by 32.2% and 29.9% (p < 0.001) and SGA (3 × 3 cm) by 22.1% and 17.1% (p = 0.015) during the fixed- and ramped-humidity exercise periods, respectively. Evaporative heat loss was enhanced by 27% (p = 0.010), heat-storage reduced by 72% (p = 0.024) and P crit was greater in taurine vs placebo (25.0-mmHg vs 21.7-mmHg; p = 0.002)., Conclusion: Taurine supplementation increased sweating responses during fixed Ḣ prod in hot conditions, prior to substantial heat strain and before the breakpoint of compensability, demonstrating improved thermoregulatory capacity. The enhanced evaporative cooling and reduced heat-storage delayed the subsequent upward inflection in T core -represented by a greater P crit -and offers a potential dietary supplementation strategy to support thermoregulation., (© 2024. The Author(s).)

Background: To mitigate health risks associated with occupational heat stress, workers are advised to adhere to a work-rest regimen, and hydrate regularly. However, it remains unclear if beverage temperature influences whole-body heat exchange during work-rest cycles, and if responses differ in older workers who have a blunted heat loss capacity., Methods: Ten young (mean [SD]: 22 [3] years) and 10 older (60 [4] years) males performed four 15-min bouts of moderate-intensity cycling at a fixed rate of metabolic heat production (200 W·m -2 ), each interspersed by 15-min rest in dry heat (40°C, ~12% relative humidity). On separate days, participants consumed either ice-slurry (~0°C), standardized to provide a heat transfer capacity of 75 kJ·m -2 , or an identical mass of warm fluid (37.5°C) before the first and third exercise bouts. Evaporative and dry heat exchange (direct calorimetry) and metabolic heat production (indirect calorimetry) were measured continuously to determine cumulative heat storage (summation of heat loss and heat gain) over the entire protocol. Rectal temperature was also measured continuously., Results: Relative to warm fluid, ice-slurry ingestion reduced cumulative heat storage in young (69 [181] vs. 216 [94] kJ) and older males (90 [104] vs. 254 [140] kJ, main effect: p < 0.01), but was unaffected by age (p = 0.49). However, rectal temperature was unaffected by beverage temperature in both groups (all p ≥ 0.15)., Conclusion: We show that cold fluid ingestion is an appropriate administrative control for both young and older males as it can mitigate increases in body heat content during moderate-intensity work-rest cycles in dry heat., (© 2024 The Author(s). American Journal of Industrial Medicine published by Wiley Periodicals LLC.)

The metabolism of ectotherms is temperature-dependent, and the exponential nature of the metabolic rate- temperature relationship means that warmer temperatures are disproportionately affecting the energy balance. T SB a sb (standard met.) temperature deviation from microclimate ambient nest temperature was -3.6 °C in I P. dominula i , -2.4 °C in I P. gallicus i , and -3.3 °C in I P. biglumis i ). The energetic calculations were conducted using temperature-dependent metabolic rate models of the three I Polistes i species, I P. dominula i , I P. gallicus i and I P. biglumis i [[17], [29]], and adequate body temperature models [[4], [17]]. The nest ambient air temperatures in the three habitats were clearly elevated above the meteorological standard ambient temperature recorded by the nearest weather stations (temperature difference, I P. dominula i : 3.6 °C, I P. gallicus i : 2.4 °C, I P. biglumis i : 3.3 °C; Figure 2). [Extracted from the article]

Polistes paper wasps are a widespread taxon inhabiting various climates. They build nests in the open without a protective outer layer, which makes them vulnerable to changing temperatures. To better understand the options they have to react to environmental variation and climate change, we here compare the thermoregulatory behavior of Polistes biglumis from cool Alpine climate with Polistes gallicus from warm Mediterranean climate. Behavioral plasticity helps both of them to withstand environmental variation. P. biglumis builds the nests oriented toward east-south-east to gain solar heat of the morning sun. This increases the brood temperature considerably above the ambience, which speeds up brood development. P. gallicus, by contrast, mostly avoids nesting sites with direct insolation, which protects their brood from heat stress on hot days. To keep the brood temperature below 40–42 °C on warm days, the adults of the two species show differential use of their common cooling behaviors. While P. biglumis prefers fanning of cool ambient air onto the nest heated by the sun and additionally cools with water drops, P. gallicus prefers cooling with water drops because fanning of warm ambient air onto a warm nest would not cool it, and restricts fanning to nests heated by the sun. [ABSTRACT FROM AUTHOR]

Wasps of the genus Polistes build combs without any cover and hence are insufficiently protected against temperature fluctuations. Due to this fact, different types of thermoregulation of Polistes dominula nests were investigated using the modern method of thermography. The study of active mechanisms for nest thermoregulation revealed no brood incubation or clustering behaviour of P. dominula . Furthermore, we found out that wing fanning for cooling the nest was almost undetectable (4 documented cases). However, we could convincingly record that water evaporation is most effective for nest cooling. By the direct comparison of active (with brood and adults) and non-active (without brood and adults) nests, the start of cooling by water evaporation was detected above maximum outside temperatures of 25 °C or at nest temperatures above 35 °C. The powerful role of water in nest cooling was manifested by an average decrease of temperature of single cells of about 8 °C and a mean duration of 7 min until the cells reached again their initial temperature. The investigation of passive thermoregulatory mechanisms revealed that the architecture of the nest plays an important role. Based on the presented results, it can be assumed that the vertical orientation of cells helps maintaining the warmth of nests during the night, whereas the pedicel assists in cooling the nest during the day. Therefore, our study of nest thermoregulation has revealed that P. dominula wasps regulate the temperature of their nest actively by evaporative cooling and passively by a careful site selection and the architecture of their nests. [ABSTRACT FROM AUTHOR]

This contribution is the first of a four-part, historical series encompassing foundational principles, mechanistic hypotheses and supported facts concerning human thermoregulation during athletic and occupational pursuits, as understood 100 years ago and now. Herein, the emphasis is upon the physical and physiological principles underlying thermoregulation, the goal of which is thermal homeostasis (homeothermy). As one of many homeostatic processes affected by exercise, thermoregulation shares, and competes for, physiological resources. The impact of that sharing is revealed through the physiological measurements that we take (Part 2), in the physiological responses to the thermal stresses to which we are exposed (Part 3) and in the adaptations that increase our tolerance to those stresses (Part 4). Exercising muscles impose our most-powerful heat stress, and the physiological avenues for redistributing heat, and for balancing heat exchange with the environment, must adhere to the laws of physics. The first principles of internal and external heat exchange were established before 1900, yet their full significance is not always recognised. Those physiological processes are governed by a thermoregulatory centre, which employs feedback and feedforward control, and which functions as far more than a thermostat with a set-point, as once was thought. The hypothalamus, today established firmly as the neural seat of thermoregulation, does not regulate deep-body temperature alone, but an integrated temperature to which thermoreceptors from all over the body contribute, including the skin and probably the muscles. No work factor needs to be invoked to explain how body temperature is stabilised during exercise., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Inadvertent perioperative hypothermia (IPH) is an uncomfortable, dangerous and costly but preventable complication of surgery. For perioperative nurses to treat this condition, they must first have an accurate means of detecting it. In making clinical decisions based on patients' temperature, an important vital sign, nurses must understand how different thermometers work and be competent in their use. It is vital that patients have accurate core body temperature recorded when admitted to the Post Anaesthesia Care Unit (PACU). Infrared tympanic thermometers are a non-invasive tool regularly used by PACU nurses and provide a quick and easily obtained measurement that is a reflection of core body temperature. Despite this, uncertainty remains about the accuracy of tympanic thermometer readings and their ability to accurately estimate core temperature, leading to questions being raised about their acceptability in clinical use. This discussion paper will evaluate the use of tympanic thermometers within the PACU and identify their benefits, limitations and alternatives, as well as the competency requirements of the nurse. Clinical trials give varying results and more research is needed into both the use of tympanic thermometers in the PACU and the competence of the user. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a literature review of thermal comfort. Both rational and adaptive thermal comfort approaches are presented. An overview of the human body thermoregulatory system as well as the mathematical modelling of heat exchanged between human body and its environment in the situations of both awaked and sleeping people is presented. [Copyright &y& Elsevier]

Introduction: We tested the hypothesis that people with multiple sclerosis (MS) who experience heat sensitivity voluntarily engage in cool-seeking behavior during exercise to a greater extent than healthy controls., Methods: In a 27.0°C ± 0.2°C, 41% ± 2% RH environment, seven participants with relapsing-remitting MS who exhibited heat sensitivity and seven healthy controls completed two randomized trials cycling for 40 min (EX) at 3.5 W·kg-1 metabolic heat production, followed by 30 min recovery (REC). In one trial, participants were restricted from engaging in cooling (CON). In the other trial, participants voluntarily pressed a button to receive 2 min of ~2°C water perfusing a top (COOL). Mean skin and core temperatures and mean skin wettedness were recorded continuously. Total time in cooling provided an index of cool-seeking behavior. RPE, total symptom scores (MS only), and subjective fatigue (MS only) were recorded every 10 min., Results: Core temperature (+0.5°C ± 0.1°C) and skin wettedness (+0.53 ± 0.02 a.u.) increased but were not different between groups or trials at end exercise (P = 0.196) or end recovery (P = 0.342). Mean skin temperature was reduced in COOL compared with CON at end exercise (P ≤ 0.002), with no differences between groups (P ≥ 0.532). MS spent more total time in cooling during EX (MS, 13 ± 3 min; healthy, 7 ± 4 min; P < 0.001) but not REC (MS, 2 ± 1 min; healthy, 0 ± 1 min; P = 0.496). RPE was greater at end exercise in MS (P = 0.001). Total symptom scores increased during exercise (P = 0.005) but was not different between trials (P = 0.321), whereas subjective fatigue was not attenuated in the cooling trial (P = 0.065)., Conclusion: Voluntary cooling is augmented in MS but does not consistently mitigate perceptions of heat-related symptoms or subjective fatigue., (Copyright © 2021 by the American College of Sports Medicine.)

Objectives: Increasing obesity rates and accelerating climate change represent two global health challenges shaped by lifestyle change and human environmental modifications. Yet, few studies have considered how these issues may interact to exacerbate disease risk., Methods: In this theory article, we explore evidence that obesity-related disease and climatic changes share socio-ecological drivers and may interact to increase human morbidity and mortality risks. Additionally, we consider how obesity-climate change interactions may disproportionately affect vulnerable populations and how anthropological research can be applied to address this concern., Results: Interactions between heat stress and cardiometabolic disease represent an important pathway through which climate change and obesity-related morbidities may jointly impair health. For example, individuals with higher body fatness and obesity-related metabolic conditions (eg, type 2 diabetes) exhibit a reduced ability to dissipate heat. The risk of poor health resulting from these interactions is expected to be heterogeneous, with low- and middle-income countries, individuals of lower socioeconomic status, and minority populations facing a greater disease burden due to relative lack of resource access (eg, air conditioning). Moreover, older adults are at higher risk due to aging-associated changes in body composition and loss of thermoregulation capabilities., Conclusions: Few policy makers appear to be considering how interventions can be designed to simultaneously address the medical burden posed by increasing obesity rates and climate change. Anthropological research is well situated to address this need in a nuanced and culturally-sensitive way; producing research that can be used to support community resilience, promote holistic well-being, and improve health outcomes., (© 2020 Wiley Periodicals LLC.)

Purpose: Current occupational heat stress guidelines rely on time-weighted averaging to quantify the metabolic demands of variable-intensity work. However, variable-intensity work may be associated with impairments in whole-body total heat loss (dry + evaporative heat loss), especially in older workers, which exacerbate heat strain relative to constant-intensity work eliciting the same time-weighted average metabolic rate. We, therefore, used direct calorimetry to evaluate whether variable-intensity work would cause decrements in the average rate of whole-body total heat loss that augment body heat storage and core temperature compared with constant-intensity work in young and older men., Methods: Eight young (19-31 yr) and eight older (54-65 yr) men completed four trials involving 90 min of work (cycling) eliciting an average metabolic heat production of ~200 W·m in dry-heat (40°C, 20% relative humidity). One trial involved constant-intensity work (CON), whereas the others involved 10-min cycles of variable-intensity work: 5-min low-intensity and 5-min high-intensity (VAR 5:5), 6-min low-intensity and 4-min very high-intensity (VAR 6:4), and 7-min low- and 3-min very, very high-intensity (VAR 7:3). Metabolic heat production, total heat loss, body heat storage (heat production minus total heat loss), and core (rectal) temperature were measured throughout., Results: When averaged over each 90-min work period, metabolic heat production, total heat loss, and heat storage were similar between groups and conditions (all P ≥ 0.152). Peak core temperature (average of final 10 min) was also similar between groups and conditions (both P ≥ 0.111)., Conclusions: Whole-body total heat loss, heat storage, and core temperature were not significantly influenced by the partitioning of work intensity in young or older men, indicating that time-weighted averaging appears to be appropriate for quantifying the metabolic demands of variable-intensity work to assess occupational heat stress.

Introduction: Increasing age is associated with decrements in sweat rate that compromise whole-body total heat loss (evaporative + dry heat exchange) in both men and women during moderate-to-vigorous exercise in dry heat. Similarly, young women also display reductions in sweating (that lower evaporative heat loss) relative to young men in such conditions. Nevertheless, it remained unclear whether these effects act synergistically to exacerbate the age-related decline in whole-body total heat loss in women relative to men. We therefore assessed the interrelation between age and sex on whole-body total heat loss during light, moderate, and vigorous exercise in dry heat., Methods: To achieve this, we used direct and indirect calorimetry to assess whole-body total heat loss and metabolic heat production (respectively) in 46 men and 34 women age between 18 and 70 yr. Participants performed three, 30-min bouts of cycling at metabolic heat productions of 150 (light), 200 (moderate), and 250 (vigorous) W·m, each separated by 15-min recovery in dry heat (40°C, ~15% relative humidity)., Results: Whole-body total heat loss was ~5% lower in women relative to men during moderate and vigorous exercise (both, P < 0.01), irrespective of age. Total heat loss declined with age during moderate and vigorous exercise in both men and women (all, P < 0.050), although the rate of that decline (~4% per decade) was similar between men and women across all exercise bouts (all, P > 0.050)., Conclusions: We show that, when assessed in dry heat, whole-body total heat loss is lower in women relative to men, irrespective of age. Furthermore, total heat loss declines with increasing age in both men and women during moderate-to-vigorous exercise, albeit the rate of that decline is not appreciably modified by sex.

New Findings: What is the central question of this study? Repeated heat exposure during the summer months can enhance heat loss in humans (seasonal heat acclimatisation), but does the magnitude of that enhancement differ between young and older adults when assessed during passive heat exposure? What is the main finding and its importance? While seasonal heat acclimatisation enhanced evaporative heat loss (i.e. sweating) in both young and older adults, those improvements led to a greater reduction in body heat storage in older adults. These outcomes indicate that heat acclimatisation may confer greater thermoregulatory benefits with increasing age., Abstract: Repeated heat exposure throughout summer can enhance heat loss in humans (seasonal heat acclimatisation), although the effect of ageing on those improvements remains unclear. We therefore sought to assess thermoregulatory function in young and older adults during environmental heat exposure prior to and following seasonal heat acclimatisation, hypothesizing that the magnitude of adaptation would be greater in older relative to young adults. To achieve this, 14 young (19-27 years) and 10 older adults (55-72 years), who resided in a temperate humid-continental climate, completed a 3 h resting heat exposure (44°C, ∼30% relative humidity) in the winter-spring months as part of a larger investigation (pre-acclimatisation), before being re-evaluated using the same heat stress test following the summer months (post-acclimatisation). Whole-body dry and evaporative heat exchange, and metabolic rate were measured throughout using direct and indirect calorimetry (respectively), and used to quantify body heat storage (metabolic rate + dry heat gain - evaporative heat loss). Evaporative heat loss increased in both groups following acclimatisation, but those improvements led to a decrease in body heat storage in older (mean difference (95% CI); 213 (295, 131) kJ; P < 0.001), but not young adults (-25 (-94, 44) kJ; P = 0.458). Thus, body heat storage was greater in older compared to young adults before (222 (123, 314) kJ; P < 0.001), but not following acclimatisation (34 (-55, 123) kJ; P = 0.433). Although there is a need for larger and more controlled confirmatory studies, our findings indicate that seasonal heat acclimatisation may induce greater thermoregulatory adaptation in older compared to young adults., (© 2020 The Authors. Experimental Physiology © 2020 The Physiological Society.)

Terrestrial artiodactyls (even-toed ungulates) inhabit some of the world's most extreme environments, including arid deserts and high elevations. As medium-to-large-bodied mammals, artiodactyls have a suite of specialized physiologies to facilitate occupation of regions unavailable to other large mammals. One such physiology is selective brain cooling, wherein reduction of brain temperature below core body temperature has been demonstrated to reduce evaporative water loss. This physiology is enabled by an arterial heat-exchanger called the carotid rete. The ubiquity of the carotid rete throughout the clade, as well as its evolutionary history, is currently uninvestigated. Here, I use osteological correlates to survey clade-wide presence and morphology of the carotid rete, prior to conducting a preliminary evolutionary analysis. Nearly all living artiodactyls possess a carotid rete and are capable of selective brain cooling; however, major arteries supplying the rete are derived from different embryonic aortic arches on a suborder-specific basis. Ancestral character estimation infers this pattern of variation to be the result of independent evolutionary processes, suggesting carotid rete homoplasy arising via parallelism. This is a surprising finding given the role this structure plays in driving a physiology that has been implicated in mitigating artiodactylan responses to extreme environmental conditions. Future studies should incorporate extinct species represented in the fossil record to better parse between parallel and convergent mechanisms, as well as to better understand the relationship between the carotid rete, selective brain cooling, and survivorship of climate perturbation. Anat Rec, 2018. © 2018 Wiley Periodicals, Inc. Anat Rec, 303:308-317, 2020. © 2018 American Association for Anatomy., (© 2018 Wiley Periodicals, Inc.)

New Findings: What is the central question of this study? Black-African descendants are thought, by some, to possess genotypic adaptations conducive to survival in hot climates. We therefore assessed whether Canadian residents of black-African descent display enhanced whole-body total heat loss (evaporative plus dry heat exchange) in comparison to Caucasian Canadians during exercise eliciting matched heat-loss requirements in dry heat. What is the main finding and its importance? Neither whole-body total heat loss nor body heat storage differed significantly between groups, irrespective of the exercise intensity. Our findings indicate that genotypic adaptations associated with ethnicity do not appreciably modify whole-body heat exchange during exercise-heat stress., Abstract: Ethnicity has long been thought to modulate thermoregulatory function; however, an evaluation of whole-body heat exchange in men of black-African descent and Caucasian men (white-European descendants), born and raised in the same climate, during exercise eliciting matched heat-loss requirements remained unavailable. We therefore used direct calorimetry to assess whole-body total heat loss (evaporative plus dry heat exchange) in young (18-30 years of age), second-generation (or higher) black-African (n = 11) and Caucasian (n = 11) men. Participants performed three 30 min bouts of semi-recumbent cycling at fixed metabolic heat productions (and therefore matched heat-loss requirements between groups) of 200 (light), 250 (moderate) and 300 W m -2 (vigorous), each followed by 15 min recovery, in dry heat (40°C, ∼13% relative humidity). Across all exercise bouts, dry (P = 0.435) and evaporative (P = 0.600) heat exchange did not differ significantly between groups. As such, total heat loss during light, moderate and vigorous exercise was similar between groups (P = 0.777), averaging [mean (SD)] 177 (10), 217 (13) and 244 (20) W m -2 in black-African men and 172 (13), 212 (17) and 244 (17) W m -2 in Caucasian men. Accordingly, body heat storage across all exercise bouts (summation of metabolic heat production and total heat loss) was also similar between the black-African [568 (142) kJ] and Caucasian groups [623 (124) kJ; P = 0.356]. We demonstrated that, when assessed in young, second-generation (or higher) black-African and Caucasian men during exercise eliciting matched heat-loss requirements in dry heat, ethnicity did not significantly modulate whole-body dry and evaporative heat exchange or the resulting changes in total heat loss and body heat storage., (© 2019 The Authors. Experimental Physiology © 2019 The Physiological Society.)

Aim. This article discusses the clinical implications of adverse health outcomes derived during heatwaves for people with mental health disorders, substance misuse and those taking prescribed medications such as lithium, various neuroleptic and anticholinergic drugs. Background. With climate change it is predicted that the incidence of prolonged periods of extreme heat will increase. Specific adverse health outcomes associated with high environmental temperatures include heat stroke and heat exhaustion. Those at increased risk for heat-related mortality are those with chronic health conditions, including those with mental health disorders and substance misuse. Data sources. Sources of evidence included and 'grey' literature published between 1985 and 2010, such as key texts, empirical research, public policies, training manuals and community information sheets on heat waves. Discussion. Current clinical practice and clinical impact of heatwaves on those people with comorbidity is explored. This includes the physiological components of heat stress, heat regulation, and the impact of alcohol and other drugs; and, ramifications and professional practice issues for those with mental health conditions and those requiring mental health medications. Implications for nursing. Client education covering modification of the environment and the use of client heat safety action plans. Secure, accessible stores of prescribed medication are recommended and emergency substance withdrawal kits could be made available. Conclusion. All nurses have a responsibility to increase the capability and resilience of their clients to manage their chronic health needs during a heatwave. At these times nurses need to give extra monitoring and assistance when clients lack the capacity or resources to protect themselves. [ABSTRACT FROM AUTHOR]

Social insects depend on their nests for protection against predation and abiotic threats. Accordingly, the chemical compounds present in the material wasps use to build their nests can both facilitate communication and repel predators. It is herein hypothesized that different wasp species build their nests with different structure and substrate materials and that such materials consist of chemical compounds related to unique wasp behavior and outside temperature variation. To test this hypothesis, nests were collected from three species of social wasps, the samples of which were subjected to temperature variation under laboratory conditions. The compounds present in the substrate were analyzed by gas chromatography coupled to mass spectrometry. Chemical compounds identified in the nest material of the three species responded differently to temperature variation. Chemical compounds from Polybia nests were altered significantly when subjected to temperature variation, whereas the nests of Polistes versicolor did not significantly change in relation to the control. The differences found between Polistes and Polybia nests may be related to genetic factors, but also to the type of nest they construct. It is possible that divergent evolutionary strategies for maintaining colony temperature, as a function of the chemical composition of the nests, may have appeared between wasps that have open and closed nests. In relatively small colonies, nest substrate is more resistant to temperature variation because it is composed of a greater diversity of elements and thus capable of holding heavier, longer carbon chains. Our results suggest that chemical compounds in the nest material of the three wasp species analysed responded differently to fluctuating ambient temperatures and that such variation could result from the biochemical differences of unique wasp species or from thermoregulation strategies of colonies., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

During the 99 years of its history, the Journal of Comparative Physiology A has published many of the most influential papers in comparative physiology and related disciplines. To celebrate this achievement of the journal's authors, annual Editors' Choice Awards and Readers' Choice Awards are presented. The winners of the 2023 Editors' Choice Awards are 'Contact chemoreception in multi‑modal sensing of prey by Octopus' by Buresch et al. (J Comp Physiol A 208:435–442, 2022) in the Original Paper category; and 'Magnetic maps in animal navigation' by Lohmann et al. (J Comp Physiol A 208:41–67, 2022) in the Review/Review-History Article category. The winners of the 2023 Readers' Choice Awards are 'Coping with the cold and fighting the heat: thermal homeostasis of a superorganism, the honeybee colony' by Stabentheiner et al. (J Comp Physiol A 207:337–351; 2021) in the Original Paper category; and 'Einstein, von Frisch and the honeybee: a historical letter comes to light' by Dyer et al. (J Comp Physiol A 207:449–456, 2021) in the Review/Review-History category. [ABSTRACT FROM AUTHOR]

This study investigated the impact of a multiday heatwave on nocturnal physiology, behavior, and sleep under controlled conditions with comprehensive monitoring of environmental factors and participant activities. Seven young healthy males were confined for 10 days in controlled conditions that ranged between hot-to-warm (day: 35.4 °C, night: 26.3 °C) during nights 4-6 and temperate (day: 25.4 °C, night: 22.3 °C) before (nights 1-3) and after (nights 7-10) the heatwave. Measurements included core and skin temperatures, heart rate, sympathovagal balance, vasomotion indicators, urine samples, blanket coverage, subjective sleep assessments, and partial polysomnography. The average nocturnal core temperature was 0.2 °C higher during and after the heatwave compared to the pre-heatwave period, with this difference being more pronounced (+0.3 °C) in the first 2 h of sleep ( p <  0.001). For every 0.1 °C rise in overnight core temperature, the total sleep time decreased by 14 min (pseudo- R 2  = 0.26, p  = 0.01). The elevated core temperatures occurred despite the participants exhibiting evident thermoregulatory behavior, as they covered 30% less body surface during the heatwave compared to pre- and post-heatwave periods ( p <  0.001). No differences in other responses, including heart rate and vasomotion indicators, were observed. The paper details a 20-min sleepwalking episode that was coupled with marked changes in sleepwalker's thermophysiological responses. In conclusion, the simulated heatwave resulted in higher overnight core temperature which was associated with reduced total sleep time. Behavioral thermoregulation during sleep may serve as a defense against these effects, though more research is needed.p <  0.001). No differences in other responses, including heart rate and vasomotion indicators, were observed. The paper details a 20-min sleepwalking episode that was coupled with marked changes in sleepwalker's thermophysiological responses. In conclusion, the simulated heatwave resulted in higher overnight core temperature which was associated with reduced total sleep time. Behavioral thermoregulation during sleep may serve as a defense against these effects, though more research is needed.

Background: Ethyl alcohol (ethanol) consumption is ostensibly known to increase the risk of morbidity and mortality during hot weather and heatwaves. However, how alcohol independently alters physiological, perceptual, and behavioral responses to heat stress remains poorly understood. Therefore, we conducted a systematic scoping review to understand how alcohol consumption affects thermoregulatory responses to the heat., Methods: We searched five databases employing the following eligibility criteria, studies must have: 1) involved the oral consumption of ethanol, 2) employed a randomized or crossover-control study design with a control trial consisting of a volume-matched, non-alcoholic beverage, 3) been conducted in healthy adult humans, 4) reported thermophysiological, perceptual, hydration status markers, and/or behavioral outcomes, 5) been published in English, 6) been conducted in air or water at temperatures of > 28°C, 7) involved passive rest or exercise, and 8) been published before October 4th, 2023., Results: After removing duplicates, 7256 titles were screened, 29 papers were assessed for eligibility and 8 papers were included in the final review. Across the 8 studies, there were a total of 93 participants (93 male/0 female), the average time of heat exposure was 70 min and average alcohol dose was 0.68 g·kg 1 . There were 23 unique outcome variables analyzed from the studies. The physiological marker most influenced by alcohol was core temperature (lowered with alcohol consumption in 3/4 studies). Additionally, skin blood flow was increased with alcohol consumption in the one study that measured it. Typical markers of dehydration, such as increased urine volume (1/3 studies), mass loss (1/3 studies) and decreased plasma volume (0/2 studies) were not consistently observed in these studies, except for in the study with the highest alcohol dose., Conclusion: The effect of alcohol consumption on thermoregulatory responses is understudied, and is limited by moderate doses of alcohol consumption, short durations of heat exposure, and only conducted in young-healthy males. Contrary to current heat-health advice, the available literature suggests that alcohol consumption does not seem to impair physiological responses to heat in young healthy males., (© 2024. The Author(s).)

The cold-induced vasodilation (CIVD) response of the human body to Arctic-like environments helps delay or prevent cold injuries to peripheral regions, such as the hands and feet. To more comprehensively predict the thermal responses of these body regions to cold stress, here we extended our previously developed and validated anatomically accurate three-dimensional whole-body thermoregulatory human model by incorporating a new phenomenological formulation of the CIVD mechanism. In this formulation, we modulated the cyclic vasodilation and vasoconstriction flow of warm blood from the body core to the peripheral regions solely by determining the heat-transfer exchange between the skin and the surrounding environment, and deactivated it when the core body temperature decreased to 36.5 °C. In total, we calibrated and validated the model using eight distinct studies involving 153 unique male subjects exposed to 10 diverse experimental conditions, including cold-air exposure of the whole body as well as air exposure and cold-water immersion of the hand or the foot. With CIVD incorporated, the model predictions generally yielded root mean square errors (RMSEs) of <3.0 °C for skin temperature, which represented a reduction of up to 3.6 °C compared to when we did not consider CIVD. Similarly, the incorporation of CIVD increased the fraction of predictions within two standard errors of the measured data by up to 63 %. The model predictions yielded RMSEs for core body temperature of <0.2 °C. The model can be used to provide guidelines to reduce the risk of cold-related injuries during prolonged exposures to very-cold environments., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could appear to have influenced the work reported in this paper., (Published by Elsevier Ltd.)

Many of the negative physiological effects of lead involve the hypothalamus, but the possibility that thermoregulation is affected has received little attention. We tested the hypothesis that lead exposure reduces avian thermoregulatory performance under hot conditions in pied crows (Corvus albus) experimentally exposed to lead in their diet. Crows in our high lead treatment (blood [Pb] = 87.3 ± 44.7 μg dL -1 ) showed significantly higher air temperature (T air ) inflections for evaporative water loss (EWL) and resting metabolic rate (RMR) compared to control (6.4 ± 1.8 μg dL -1 ) or intermediate (53.9 ± 23.7 μg dL -1 ) lead groups, which did not differ. EWL, RMR and body temperature (T b ) all increased more rapidly at T air > T b in the high lead treatment. In contrast, neither maximum T air tolerated by the crows nor maximum T b varied with treatment. Our data reveal that water and energy balance during hot weather is affected by lead exposure., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

The wet bulb globe temperature (WBGT)-based occupational exposure limits (OELs) were developed from steady exposures to heat stress at constant WBGT and metabolic rate (M). The exposure limits were based on compensable heat stress exposures at the upper limit of the prescriptive zone for most healthy people. Professional practice allows for using time-weighted averages (TWAs) of WBGT and M to account for heterogeneous heat stress exposures. The purpose of the current paper was to report on the effectiveness of time-weighted averaging to assess occupational heat stress using published studies. Our hypothesis was using TWA-WBGT and TWA-M was as protective as the recommended OELs for steady exposures. The current paper reports on 62 observations of work that alternate between at least two heat stress conditions (usually work and recovery) reported in 16 papers. The TWA-WBGT and TWA-M were determined for all observations. ΔLimit was the observed TWA-WBGT minus the exposure limit at the TWA-M based on acclimatization state. The observations were then classified as above or below ΔLimit = 0. Each observation was also classified as uncompensable if the mean core temperature for the group was greater than 38°C or a less tolerant individual was above 38.5°C. When comparing exposure classifications to outcome classifications using 2 × 2 tables, the sensitivity and specificity for all observations were 0.72 and 0.73, respectively. The sensitivity was much less than the expected value near 1.0, and the large difference called into question the ability of TWAs to represent actual heat stress. There was some suspicion that there were differences between acclimatized and unacclimatized observations. Before any of these findings are embedded in policy or practice, a more careful evaluation of TWAs is required. In conclusion, we believe that the use of TWAs for heat stress analysis was not fully evaluated, and we proposed a framework for evaluation. [ABSTRACT FROM AUTHOR]

Reference: Zhang Y, Davis JK, Casa DJ, Bishop PA. Optimizing cold water immersion for exercise-induced hyperthermia: a meta-analysis. Med Sci Sports Exerc. 2015;47(11): 2464-2472. Clinical Questions: Do optimal procedures exist for implementing cold-water immersion (CWI) that yields high cooling rates for hyperthermic individuals? Data Sources: One reviewer performed a literature search using PubMed and Web of Science. Search phrases were cold water immersion, forearm immersion, ice bath, ice water immersion, immersion, AND cooling. Study Selection: Studies were included based on the following criteria: (1) English language, (2) full-length articles published in peer-reviewed journals, (3) healthy adults subjected to exercise-induced hyperthermia, and (4) reporting of core temperature as 1 outcome measure. A total of 19 studies were analyzed. Data Extraction: Pre-immersion core temperature, immersion water temperature, ambient temperature, immersion duration, and immersion level were coded a priori for extraction. Data originally reported in graphical form were digitally converted to numeric values. Mean differences comparing the cooling rates of CWI with passive recovery, standard deviation of change from baseline core temperature, and within-subjects r were extracted. Two independent reviewers used the Physiotherapy Evidence Database (PEDro) scale to assess the risk of bias. Main Results: Cold-water immersion increased the cooling rate by 0.03°C/min (95% confidence interval [CI]=0.03, 0.04°C/ min) compared with passive recovery. Cooling rates were more effective when the pre-immersion core temperature was ≥38.6°C (P = .023), immersion water temperature was ≤10°C (P = .036), ambient temperature was ≥20°C (P = .013), or immersion duration was ≤10 minutes (P < .001). Cooling rates for torso and limb immersion (mean difference = 0.04°C/min, 95% CI=0.03, 0.068C/min) were higher (P=.028) than those for forearm and hand immersion (mean difference = 0.018°C/min, 95% CI =-0.01, 0.04°C/min). Conclusions: Hyperthermic individuals were cooled twice as fast by CWI as by passive recovery. Therefore, the former method is the preferred choice when treating patients with exertional heat stroke. Water temperature should be <10°C, with the torso and limbs immersed. Insufficient published evidence supports CWI of the forearms and hands. [ABSTRACT FROM AUTHOR]

Temperature is a primary factor influencing organismal development, and the fluctuating daily and seasonal thermal regimes of temperate climates may challenge the ability of viviparous reptiles to optimize body temperatures during gestation. Testing how viviparous reptiles navigate highly variable thermal conditions (e.g., relatively cold nights and/or highly fluctuating temperatures) is a powerful way to understand how they use microhabitats for thermoregulatory benefits. We assessed the thermal ecology of pregnant and non-pregnant female Prairie Rattlesnakes (Crotalus viridis) inhabiting a high-elevation, montane shrubland in northwest Colorado throughout their short summer active season, addressing the thermal consequences of microhabitat selection with a focus on thermoregulation of pregnant females at communal rookery sites. We deployed operative temperature models to collect data on the thermal quality of microhabitats used by the snakes, and calculated thermoregulatory accuracy of the snakes by comparing their field-active body temperatures with preferred body temperatures of snakes placed in a thermal gradient. Pregnant females inhabited rocky, hilltop rookeries that had higher thermal quality due to higher and less variable nighttime temperatures compared to microhabitats in the surrounding prairie. Pregnant females therefore thermoregulated more accurately than non-pregnant females. The difference was most pronounced during the night, when pregnant females at rookeries maintained higher body temperatures than non-pregnant snakes in the prairie. Our results support the hypothesis that one major reason female rattlesnakes at high latitudes and/or high elevations forgo migration and gestate at communal, rocky, hilltop rookeries is that, relative to prairie microhabitats, they provide better conditions for thermoregulation during pregnancy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Hypometabolism arising from active metabolic suppression occurs in several contexts among endotherms, particularly during heterothermic states such as torpor. However, observed Q 10  ≈ 1 for avian resting metabolic rate within the thermoneutral zone, values far below the Q 10  = 2-3 expected on the basis of Arrhenius effects, suggests hypometabolism also plays a role in birds' thermoregulation at environmental temperatures approaching or exceeding normothermic body temperature (T b ). We evaluated the occurrence of hypometabolism during heat exposure among birds by re-analysing literature data to quantify changes in T b and resting metabolic rate (RMR) near the upper boundary of the thermoneutral zone, at air temperatures (T air ) between the inflection above which T b increases above normothermic levels (T b.inf ) and the upper critical limit of thermoneutrality (T uc ). Among the ∼55 % of species in which T uc - T b.inf > 0, Q 10  < 2-3 occurred in nine of 10 orders for which suitable data exist, indicating that hypometabolism during heat exposure is widespread across the avian phylogeny. Values of Q 10  < 2-3 were not restricted to small body mass, as previously proposed. Our findings support the idea that metabolic suppression reduces avian metabolic heat production and hence evaporative cooling requirements during heat exposure, with reductions of 20-30 % in RMR in some species. Moreover, these findings add to evidence that hypometabolism is an important component of heat tolerance among endotherms such as birds and tropical arboreal mammals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Today, energy-efficient resource management is an important task. This study aims to improve the energy efficiency of the cooling system of a technical room by developing a transparent and explainable temperature adaptation tuning algorithm based on the combination of PID control and fuzzy logic methods. This work focuses on the design and development of a hardware and software system consisting of a microcontroller and a temperature sensor. This paper analyzes temperature control based on PID and fuzzy controllers and proposes a combined method to allow for more accurate temperature control tuning. The experimental results show that the combined method reduces the rise time by at least 5%, the stabilization time by at least 17%, and the power consumption by at least 21%. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Location Time Period Major Taxa Studied Methods Results Main Conclusions Climate change is altering forest communities at an unprecedented pace. Current knowledge on trees' responses to climate shifts is based mostly on adults. Yet, germination traits and intraspecific variation can notably modulate species niches. This paper provides a quantitative review about warming effects on tree species' germination, the role of population effects and its implications under future climate.Global; covering boreal, temperate, Mediterranean and tropical–subtropical biomes.1996–2024.Tree species.We reviewed 50 papers addressing 63 species and 250 populations. Then, we conducted a meta‐analysis to assess warming effects on germination percentage and time, and how germination is modulated by climate at seed origin. We further evaluated populations' adaptation to local temperature on 27 species. Finally, we estimated population‐based germination niches in eight of these species under current climate conditions and a 2080 climate scenario (SSP5‐8.5).Warming induced more consistent shifts in germination time than in percentage across biomes, hastening germination. Temperature at seed origin shaped responses to warming in boreal and temperate species. In Mediterranean and tropical–subtropical species, different responses were associated with variation in precipitation‐related variables. Local adaptation was more frequent in species from the tropics, while adaptation lags towards warmer‐than‐today conditions observed in the other biomes. Simulation of germination niches yielded slight although extensive germination reductions in tropical–subtropical species under future climate, whereas the temperate and boreal ones showed overall increases.Population‐level adjustments are key moderators of germination percentage and phenology response to warming. Their roles vary depending on the prevailing climate in each biome. Temperature at seed origin is an important factor modulating temperate and boreal species' responses, while precipitation‐related variables are more relevant in Mediterranean and tropical–subtropical ones. Local adaptation in the tropical species increases their vulnerability to warming. [ABSTRACT FROM AUTHOR]

Piglets are born wet, and evaporation of that moisture decreases body temperature, increasing the risk of mortality. The objective of this study was to compare the effect of two commercially applicable methods for drying piglets at birth on piglet rectal temperature over 24 h after birth. The study was carried out in standard commercial farrowing facilities with 52 litters, using a completely randomized design with three Drying Treatments: Control (not dried); Desiccant (dried at birth using a cellulose-based desiccant); Paper Towel (dried at birth using paper towels). Litters were randomly allotted to treatments at the birth of the first piglet. At birth, piglets were individually identified, and the treatment was applied. Rectal temperature was measured at 0, 10, 20, 30, 45, 60, 120, and 1,440 min (24 h) after birth. Data were analyzed using a repeated measures model with PROC MIXED of SAS, with litter as the experimental unit and piglet a subsample of the litter. The model included the fixed effects of treatment and time (as a repeated measure), and the interaction. There was no effect (P > 0.05) of treatment on temperature at birth, or 10 or 1,440 min after birth. Piglet temperatures between 20 and 120 min after birth were similar (P > 0.05) for the Desiccant and Paper Towel treatments, but were greater (P ≤ 0.05) than the Control. The effect of birth weight on the response to Drying Treatment was evaluated by dividing the data into Light (<1.0 kg), Medium (1.0 to 1.5 kg), or Heavy (>1.5 kg) piglet Birth Weight Categories. Piglet rectal temperature data at each measurement time were analyzed using a model that included the fixed effects of Birth Weight Category, Drying Treatment, and the interaction. Temperatures of Light piglets were lower (P ≤ 0.05) than those of Heavy piglets between 20 and 120 min after birth, with Medium piglets being intermediate and generally different to the other two weight categories at these times. The difference in temperature between Light as compared with Medium or Heavy piglets was greater for the Control than the other two Drying Treatments at 60 min after birth. These results suggest that drying piglets at birth is an effective method to reduce rectal temperature decline in the early postnatal period, especially for low birth weight piglets. [ABSTRACT FROM AUTHOR]