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One part per hundred thousand, per cent mille (pcm) or milli-percent denotes one part per 100,000 (10 5) parts, and a value of 10 −5. It is commonly used in epidemiology for mortality, crime and disease prevalence rates, and nuclear reactor engineering as a unit of reactivity.
1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).
The concentrations of carbon dioxide in the atmosphere are expressed as parts per million by volume (abbreviated as ppmv, or ppm(v), or just ppm). To convert from the usual ppmv units to ppm mass (abbreviated as ppmm, or ppm(m)), multiply by the ratio of the molar mass of CO 2 to that of air, i.e. times 1.52 (44.01 divided by 28.96).
After a decade of near-zero growth in methane levels, "globally averaged atmospheric methane increased by [approximately] 7 nmol/mol per year during 2007 and 2008. During the first half of 2009, globally averaged atmospheric CH 4 was [approximately] 7 nmol/mol greater than it was in 2008, suggesting that the increase will continue in 2009."
By using a laser that is locked to an atomic transition, a CCD or PMT will detect the laser induced fluorescence to allow highly selective, parts-per-trillion to parts-per-quadrillion concentration measurement with single atom detection. [1]
Jeff Bezos, Elon Musk say human population not nearly big enough: ‘If we had a trillion humans, we would have at any given time a thousand Mozarts’ Steve Mollman December 16, 2023 at 9:01 AM
Broadcom's AI revenue grew 220% to $12.2 billion this past quarter, pushing semiconductor revenue to a record $30.1 billion.
Here's what we know about the tuberculosis outbreak in Kansas right now, plus how the infection spreads. Meet the expert : Thomas Russo, MD, is a professor and chief of infectious disease at the ...