( ( a -RRB- ) ( ( ( Convert ( the half-life ) ) ( into ( ( a decay ) ( constant ( in ( units ( of ( s -1 ) ) ) ) ) ) ) ) . ) )
(ROOT (S (LST (LS a) (-RRB- -RRB-)) (VP (VB Convert) (NP (DT the) (NN half-life)) (PP (IN into) (NP (NP (DT a) (NN decay)) (ADJP (JJ constant) (PP (IN in) (NP (NP (NNS units)) (PP (IN of) (NP (NNP s) (CD -1))))))))) (. .)))
a) Convert the half-life into a decay constant in units of s -1 .
(ROOT (S (NP (DT The) (NN decay) (NN rate)) (VP (VBZ is) (VP (VBN measured) (PP (IN in) (NP (NP (DT a) (NN unit)) (VP (VBN called) (NP (DT the) (NN half-life))))))) (. .)))