  We recently detected variations in extreme ultraviolet intensity in coronal
loops repeating with periods of several hours. Models of loops including
stratified and quasi-steady heating predict the development of a state of
thermal non-equilibrium (TNE): cycles of evaporative upflows at the footpoints
followed by falling condensations at the apex. Based on Fourier and wavelet
analysis, we demonstrate that the observed periodic signals are indeed not
signatures of vibrational modes. Instead, superimposed on the power law
expected from the stochastic background emission, the power spectra of the time
series exhibit the discrete harmonics and continua expected from periodic
trains of pulses of random amplitudes. These characteristics reinforce our
earlier interpretation of these pulsations as being aborted TNE cycles.
