News tagged with heat

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Heat waves reduce length of pregnancy

When temperatures reach 32°C or higher over a period of four to seven days, the risk of early-term delivery is 27% higher than on typical summer days, according to a study led by Nathalie Auger of the University ...

Apr 01, 2014
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Dealing with the deep freeze

(HealthDay)—As another blast of Arctic air sends millions of Americans into a prolonged deep freeze, doctors are offering advice on dealing with dangerously frigid temperatures.

Jan 23, 2014
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Older firefighters may be more resilient to working in heat

Older firefighters who are chronically exposed to heat stress on the job could be more heat resilient over time. A recent study published in the December issue of the Journal of Occupational and Environmental Hygiene (JOEH) ...

Jan 08, 2014
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Hypothermia and older adults

Frigid weather can pose special risks to older adults. The National Institute on Aging (NIA), part of the National Institutes of Health, has some advice for helping older people avoid hypothermia—when the body gets too ...

Jan 07, 2014
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Heat

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