Obstetrics & gynaecology

How the contraceptive pill could help female athletes stay cool

If all goes to plan, athletes will compete in hot conditions at the rescheduled 2021 Tokyo Summer Olympics. Indeed, summers in Japan can be quite intense—with hot and humid weather and temperatures reaching up to 35°C.

Biomedical technology

Aerobuster hunts for coronaviruses

Aerosols play an important role in the spreading of COVID 19. When breathing, speaking, or coughing, these small droplets loaded with coronaviruses disperse in indoor air. Schools, kindergartens, lecture halls of universities, ...

Biomedical technology

Video: The brain during a heart attack

State-of-the-art photoacoustic microscopy (imaging using the heat given off by lasers) shows the blood flow in a mouse brain before, during, and after cardiac arrest, showing the drastic change in the brain's blood flow when ...

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In physics and thermodynamics, heat is the process of energy transfer from one body or system to another due to a difference in temperature. In thermodynamics, the quantity TdS is used as a representative measure of the (inexact) heat differential δQ, which is the absolute temperature of an object multiplied by the differential quantity of a system's entropy measured at the boundary of the object.

A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature. Heat is also loosely referred to as thermal energy, although many definitions require this thermal energy to actually be in the process of movement between one body and another to be technically called heat (otherwise, many sources prefer to continue to refer to the static quantity as "thermal energy"). Heat is also known as "Energy".

Energy transfer by heat can occur between objects by radiation, conduction and convection. Temperature is used as a measure of the internal energy or enthalpy, that is the level of elementary motion giving rise to heat transfer. Energy can only be transferred by heat between objects - or areas within an object - with different temperatures (as given by the zeroth law of thermodynamics). This transfer happens spontaneously only in the direction of the colder body (as per the second law of thermodynamics). The transfer of energy by heat from one object to another object with an equal or higher temperature can happen only with the aid of a heat pump, which does work.

This text uses material from Wikipedia, licensed under CC BY-SA