We present an ab initio calculation of single ionization, harmonic gen
eration, and double excitation of helium by short (3.8-15.2 fs) modera
tely strong (peak intensity 1.49 x 10(14) W/cm(2)) laser pulses with w
avelengths between 40 and 152 nm. We find excitation to be dominated b
y resonances with bound and doubly excited states. The processes are n
onperturbative. The finite pulse duration leads to resonance broadenin
g and far-off-resonant transitions.