Where does heat collide?

In thermodynamics, heat is energy transferred between a system and its surroundings because of a temperature difference alone, not a substance a body contains and not the temperature of that body. Zemansky's 1970 article The Use and Misuse of the Word "Heat" in Physics Teaching insisted that heat is energy in transit: once it has crossed the boundary it becomes part of the body's internal energy and is no longer called heat, and the first law writes it as the quantity Q that, together with work, changes that internal energy. The referent is a flow of energy driven by a temperature gap, measured in joules, and it is not a qualifying round that narrows a field of racers, nor the fertile phase of a female animal.[1]

Unit

A quantity of energy crossing a system boundary, in joules

Recovery means

Not applicable

Measured by

Inferred from temperature change and heat capacity by calorimetry, reported as energy in joules

In reproductive biology, estrus, an animal being "in heat", is the recurring phase of the reproductive cycle when a female mammal is sexually receptive and fertile, marked by hormonal, behavioral, and physiological signs of readiness to mate. Ajayi and Akhigbe's 2020 review Staging of the estrous cycle and induction of estrus in experimental rodents set out how the phases of the cycle are identified and how estrus, the receptive phase they gloss plainly as heat, is recognised and induced. The referent is a timed biological state of an individual animal, scored by the stage of its cycle, and it is unrelated to energy crossing a boundary or to a qualifying round of a race.[2]

Unit

The receptive, fertile phase within a female's reproductive cycle

Recovery means

The cycle passes back through its resting phase before the next estrus returns

Measured by

Staged by vaginal cytology and by observed behavioral receptivity across the cycle