  We present over 6.5 years of frequent X-ray observations of the NLS1 galaxy
NGC4051 by RXTE together with a >100ks observation by XMM-Newton and so derive
a 2-10 keV PSD covering an unprecedent frequency range of over 6.5 decades from
<10^-8 to >10^-2 Hz. This PSD is a very good match to the PSD of the galactic
black hole binary system (GBH) Cyg X-1 when in a `high', rather than `low',
state providing the first definite confirmation of an AGN in a `high' state. A
bending, rather than sharply broken, powerlaw is a better description of the
PSDs of Cyg X-1 in the high state and of NGC4051. At low frequencies the PSD of
NGC4051 has a slope of -1.1 bending, at nu_B = 8 x 10^-4 Hz, to a slope of
alpha_H ~ -2 (steeper at lower energies). If nu_B scales with mass, we imply a
black hole mass of 3 x 10^5 Msolar in NGC4051, consistent with the 5 x 10^5
Msolar reverberation value. Hence NGC4051 is emitting at ~30% L_Edd.
  NGC4051 follows the same rms-flux relationship as GBHs. Phase lags and
coherence between bands are also the same as in GBHs. The lag of soft by hard
photons increases, and coherence decreases, as band separation increases. The
lag, and coherence, are greater for variations of longer Fourier period. This
behaviour suggests that higher photon energies and shorter variability
timescales are associated with smaller radii. Using also data from the
literature, we cannot fit all AGN to the same linear scaling of break timescale
with black hole mass. However broad line AGN are consistent with a linear
scaling from Cyg X-1 in its low state and NLS1 galaxies scale better with Cyg
X-1 in its high state. We suggest that the relationship between black hole mass
and break timescale is a function of at least one other underlying parameter,
which may be accretion rate or black hole spin.
