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Newborns transitioning into extrauterine life will undergo periods of reactivity. These periods are divided into three stages. The first stage occurs in the first 30 minutes of life; during this stage the infant is alert and responsive with heart rate peaking at 160-180 beats per minute and then stabilizes to a baseline rate of 100-120 beats ...
The early arrival of a baby before the 37th week of gestation is one of the leading causes of infant mortality, and is linked to a range of health problems for surviving infants, including lung ...
The law holds well for forced air and pumped liquid cooling, where the fluid velocity does not rise with increasing temperature difference. Newton's law is most closely obeyed in purely conduction-type cooling. However, the heat transfer coefficient is a function of the temperature difference in natural convective (buoyancy driven) heat transfer.
Convective heat transfer, or simply, convection, is the transfer of heat from one place to another by the movement of fluids, a process that is essentially the transfer of heat via mass transfer. The bulk motion of fluid enhances heat transfer in many physical situations, such as between a solid surface and the fluid. [10]
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Convection-cooling is sometimes loosely assumed to be described by Newton's law of cooling. [6] Newton's law states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings while under the effects of a breeze. The constant of proportionality is the heat transfer coefficient. [7]
Humans adapted to heat early on. In Africa, the climate selected for traits that helped them stay cool. Also, humans had physiological mechanisms that reduced the rate of metabolism and that modified the sensitivity of sweat glands to provide an adequate amount for cooldown without the individual becoming dehydrated.
A 2022 study on the effect of heat on young people found that the critical wet-bulb temperature at which heat stress can no longer be compensated, T wb,crit, in young, healthy adults performing tasks at modest metabolic rates mimicking basic activities of daily life was much lower than the 35°C usually assumed, at about 30.55°C in 36–40°C ...