decay level
51radioactivity — /ray dee oh ak tiv i tee/, n. Physics, Chem. the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element. Also called activity. [1895… …
52Decline of the Roman Empire — This article is about the historiography of the decline of the Roman Empire. For a description of events, see Roman Empire. For the book by Edward Gibbon, see The History of the Decline and Fall of the Roman Empire. For the film, see The Fall of… …
53Mathematics and Physical Sciences — ▪ 2003 Introduction Mathematics Mathematics in 2002 was marked by two discoveries in number theory. The first may have practical implications; the second satisfied a 150 year old curiosity. Computer scientist Manindra Agrawal of the… …
54Corium (nuclear reactor) — LFCM redirects here. For the airport, see List of airports by ICAO code: L. The Three Mile Island reactor 2 after the meltdown. Corium, also called fuel containing material (FCM) or lava like fuel containing material (LFCM), is a lava like molten …
55Nuclear drip line — In nuclear physics, the boundaries for nuclear particle stability are conceptualized as drip lines. The nuclear landscape is understood by plotting boxes, each of which represents a unique nuclear species, on a graph with the number of neutrons… …
56Nuclear meltdown — Three of the reactors at Fukushima I overheated, causing core meltdowns. This was compounded by hydrogen gas explosions and the venting of contaminated steam which released large amounts of radioactive material into the air.[1] …
57Nuclear and radiation accidents — This article is about nuclear and radiation accidents in general. For a list of military nuclear accidents, see List of military nuclear accidents. For a list of civilian nuclear accidents, see List of civilian nuclear accidents. For a discussion …
58art conservation and restoration — Maintenance and preservation of works of art, their protection from future damage, deterioration, or neglect, and the repair or renovation of works that have deteriorated or been damaged. Research in art history has relied heavily on 20th and… …
59Nobel Prizes — ▪ 2009 Introduction Prize for Peace The 2008 Nobel Prize for Peace was awarded to Martti Ahtisaari, former president (1994–2000) of Finland, for his work over more than 30 years in settling international disputes, many involving ethnic,… …
60chemical element — Introduction also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. This article considers the… …
