The accuracy of predictive models (also known as mechanistic or causal models) of animal responses to climate change depends on properly incorporating the principles of heat transfer and thermoregulation into those models. Regrettably, proper incorporation of these principles is not always evident. We have revisited the relevant principles of thermal physiology and analysed how they have been applied in predictive models of large mammals, which are particularly vulnerable, to climate change. We considered dry heat exchange, evaporative heat transfer, the thermoneutral zone and homeothermy, and we examined the roles of size and shape in the thermal physiology of large mammals. We report on the following misconceptions in influential predictive models: underestimation of the role of radiant heat transfer, misassignment of the role and misunderstanding of the sustainability of evaporative cooling, misinterpretation of the thermoneutral zone as a zone of thermal tolerance or as a zone of sustainable energetics, confusion of upper critical temperature and critical thermal maximum, overestimation of the metabolic energy cost of evaporative cooling, failure to appreciate that the current advantages of size and shape will become disadvantageous as climate change advances, misassumptions about skin temperature and, lastly, misconceptions about the relationship between body core temperature and its variability with body mass in large mammals. Not all misconceptions invalidate the models, but we believe that preventing inappropriate assumptions from propagating will improve model accuracy, especially as models progress beyond their current typically static format to include genetic and epigenetic adaptation that can result in phenotypic plasticity.

We measured brain and abdominal temperatures in eight male Sprague-Dawley rats (350-450 g) exercising voluntarily to a point of fatigue in two hot environments. Rats exercised, at the same time of the day, in three different trials, in random order: rest 23 degrees C, exercise 33 degrees C; rest 23 degrees C, exercise 38 degrees C; and rest 38 degrees C, exercise 38 degrees C. Running time to fatigue was 29.4 +/- 5.9 (SD), 22.1 +/- 3.7, and 14.3 +/- 2.9 min for the three trials, respectively. Abdominal temperatures, measured with intraperitoneal radiotelemeters, at fatigue in the three trials (39.9 +/- 0.3, 39.9 +/- 0.3, and 39.8 +/- 0.3 degrees C, respectively) were not significantly different from each other. Corresponding brain temperatures, measured with thermocouples in the hypothalamic region (40.2 +/- 0.4, 40.2 +/- 0.4, and 40.1 +/- 0.4 degrees C), also did not differ. Our results are consistent with the concept that there is a critical level of body temperature beyond which animals will not continue to exercise voluntarily in the heat. Also, in our study, brain temperature was higher than abdominal temperature throughout exercise; that is, selective brain cooling did not occur when body temperature was below the level limiting exercise.

In the face of climate change, the life history traits of large terrestrial mammals will prevent them from adapting genetically at a sufficient pace to keep track with changing environments, and habitat fragmentation will preclude them from shifting their distribution range. Predicting how habitat-bound large mammals will respond to environmental change requires measurement of their sensitivity and exposure to changes in the environment, as well as the extent to which phenotypic plasticity can buffer them against the changes. Behavioural modifications, such as a shift to nocturnal foraging or selection of a cool microclimate, may buffer free-living mammals against thermal and water stress, but may carry a cost, for example by reducing foraging time or increasing predation risk. Large mammals also use physiological responses to buffer themselves against changing environments, but those buffers may be compromised by a changing physical environment. A decrease in the available food energy or water leads to a trade-off in which the precision of homeothermy is relaxed, resulting in large daily fluctuations in body temperature. Understanding how large mammals prioritise competing homeostatic systems in changing environments, and the consequences of that prioritisation for their fitness, requires long-term monitoring of identifiable individual animals in their natural habitat. Although body size predicts general ecological and energetic patterns of terrestrial mammals, high intraspecific and interspecific variability means that a species-directed approach is required to accurately model responses of large mammals to climate change.

Medical care can be improved by incorporating patients' preferences into medical decision making. We surveyed obstetric patients to determine their preferences regarding potential cesarean delivery anesthesia outcomes. Unlike general surgical patients who rate nausea and vomiting highest, parturients considered pain during and after cesarean delivery the most important concern.

Core body temperature changes across the ovulatory menstrual cycle, such that it is 0.3°C to 0.7°C higher in the post-ovulatory luteal phase when progesterone is high compared with the pre-ovulatory follicular phase. This temperature difference, which is most evident during sleep or immediately upon waking before any activity, is used by women as a retrospective indicator of an ovulatory cycle. Here, we review both historical and current literature aimed at characterizing changes in core body temperature across the menstrual cycle, considering the assessment of the circadian rhythm of core body temperature and thermoregulatory responses to challenges, including heat and cold exposure, exercise, and fever. We discuss potential mechanisms for the thermogenic effect of progesterone and the temperature-lowering effect of estrogen, and discuss effects on body temperature of exogenous formulations of these hormones as contained in oral contraceptives. We review new wearable temperature sensors aimed at tracking daily temperature changes of women across multiple menstrual cycles and highlight the need for future research on the validity and reliability of these devices. Despite the change in core body temperature across the menstrual cycle being so well identified, there remain gaps in our current understanding, particularly about the underlying mechanisms and microcircuitry involved in the temperature changes.