half-life

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half-life

(hăf′līf′, häf′-)
n.
1. Physics The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
2. Biology
a. The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. Also called biological half-life.
b. The time required for the radioactivity of material taken in by a living organism to be reduced to half its initial value by a combination of biological elimination processes and radioactive decay.

half-life

n
1. (General Physics) the time taken for half of the atoms in a radioactive material to undergo decay. Symbol: τ
2. (Biology) the time required for half of a quantity of radioactive material absorbed by a living tissue or organism to be naturally eliminated (biological half-life) or removed by both elimination and decay (effective half-life)

half′-life`

or half′ life`,



n., pl. -lives (-ˌlaɪvz)
1. the time required for one half the atoms of a given amount of a radioactive substance to decay.
2. the time required for the activity of a substance taken into the body to lose one half its initial effectiveness.
[1905–10]

half-life

(hăf′līf′)
The average time needed for half the nuclei in a sample of a radioactive substance to undergo radioactive decay. The half-life of a substance does not equal half of its full duration of radioactivity. For example, if one starts with 100 grams of radium 229, whose half-life is 4 minutes, then after 4 minutes only 50 grams of radium will be left in the sample, after 8 minutes 25 grams will be left, after 12 minutes 12.5 grams will be left, and so on.

half-life

The time required for the activity of a given radioactive species to decrease to half of its initial value due to radioactive decay. The half-life is a characteristic property of each radioactive species and is independent of its amount or condition. The effective half-life of a given isotope is the time in which the quantity in the body will decrease to half as a result of both radioactive decay and biological elimination.

half-life

1. A substance which undergoes exponential decay decays by the same ratio in equal intervals of time. The constant ratio is the half-life. The rate of radioactive decay of a substance is defined by its half-life.
2. The time in which half the atoms in a radioactive isotope decay.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.half-life - the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
period, period of time, time period - an amount of time; "a time period of 30 years"; "hastened the period of time of his recovery"; "Picasso's blue period"
Translations

half-life

[ˈhɑːflaɪf] N (half-lives (pl)) (Phys) → media vida f

half-life

[ˌhɑːfˈlaɪf] n (Phys) → tempo di dimezzamento

half-life

1. n. vida media, tiempo requerido para que la mitad de una sustancia ingerida o inyectada en el organismo se elimine por medios naturales;
2. semidesintegración, tiempo requerido por una sustancia radioactiva para perder la mitad de su radioactividad por desintegración.

half-life

n vida media
References in periodicals archive ?
En "El arte narrativo de HalfLife 2", Samy Masadi nos habla sobre las diferentes formas de narrar una historia.
Nitric oxide (NO) is a free radical gas with a halflife in vivo of only a few seconds and is known to be involved in diverse physiological and pathophysiological conditions like contractility of smooth muscles and vasodilatation,1 smooth muscle proliferation, immune response of mononuclear cells, leucocyte adhesion and anticoagulation.
Delivered in association with the King's Cross Central Partnership developer Argent, HALFLIFE is a site-specific work using the medium of light to synthesise a digital journey through light and colour.
It has a very short halflife, as well as significant instability at room temperature.
Due to the shorter biological halflife, the plateau body burden is lower for younger children, and this is why we used the Babyscan to screen small children in this study.
The exception to this is atorvastatin which has a longer halflife, so even if it is taken in the morning, it remains active through the night.
However, these SSRIs must be taken daily in order to achieve meaningful efficacy, and the long halflife increases the risk of drug accumulation in the body, which increases the risk of adverse effects such as reduced sexual libido and erectile dysfunction.
Due to the short 20-minute half-life of carbon 11, tracers labeled with fluorine-18, which display a longer halflife, have enabled amyloid imaging to be used clinically.
Halflife of CRP is 4-6 hours, therefore it returns to normal levels within 3-7 days after termination of the inflammation.
It is assumed that remifentanil with its short halflife (17) did not decrease the blood pressures after delivery in the experimental group.