Report centrifugal force in g units NOT rpm! (Rant)

[Robert Roxby]

So many centrifugation protocols give only rpm and rotor type, even in 
technical compendia devoted entirely to methods, such as Current 
Protocols in Molecular Biology.  Rotor and rpm is ambiguous unless you 
have the same centrifuge equipment as used in the original protocol, or 
have data for that equipment.  I suggest exercising some rigor in 
reporting centrifugation conditions in units of g.  It can be 
easily calculated as follows:

force (g) = w^2 *r/980 where w=2*pi*(rpm/60) and r is the distance to 
from the center of rotation to the bottom of the tube.