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Latest SI base units Stories

2008-09-23 03:00:10

By Vayshenker, I Li, X; Livigni, D J; Lehman, J H; Bermudez, J C; Molina, J C; Ruiz, Z E We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST- USA) and Centro Nacional De Metrologia (CENAM-Mexico). Open beam (free field) and optical-fiber-based measurements at wavelengths of 1302 nm and 1546 nm are reported. Both laboratories' reference standards were compared by means of a temperature-controlled optical trap...

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2008-02-28 18:53:08

Change should have little impact on nuclear weapons complexThe kilogram is losing weight and many international scientists, including some at Sandia National Laboratories, agree that it's time to redefine it.Scientists are hoping to redefine the kilogram by basing it on standards of universal constants rather than on an artifact standard.The International Prototype Kilogram (IPK) or "Le Grand K," made in the 1880s, is a bar of platinum-iridium alloy kept in a vault near Paris."The idea is to...

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2007-09-12 19:35:00

PARIS -- A kilogram just isn't what it used to be. The 118-year-old cylinder that is the international prototype for the metric mass, kept tightly under lock and key outside Paris, is mysteriously losing weight - if ever so slightly. Physicist Richard Davis of the International Bureau of Weights and Measures in Sevres, southwest of Paris, says the reference kilo appears to have lost 50 micrograms compared with the average of dozens of copies. "The mystery is that they were all made of the...


Word of the Day
jument
  • A beast of burden; also, a beast in general.
'Jument' ultimately comes from the Latin 'jugum,' yoke.
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