  The high ionization lines in active galactic nuclei (AGN), such as C IV, tend
to be blueshifted with respect to the lower ionization lines, such as H beta,
and often show a strong blue excess asymmetry not seen in the low ionization
lines. There is accumulating evidence that the H beta profile is dominated by
gravity, and thus provides a useful estimate of the black hole mass in AGN. The
shift and asymmetry commonly seen in C IV suggest that non gravitational
effects, such as obscuration and radiation pressure, may affect the line
profile. We explore the relation between the H beta and C IV profiles using UV
spectra available for 81 of the 87 z < 0.5 PG quasars in the Boroson & Green
(BG92) sample. We find the following: (1) Narrow C IV lines (FWHM < 2000 km/s)
are rare (~2 per cent occurrence rate) compared to narrow H beta lines (~20 per
cent). (2) In most objects where the H beta FWHM <4000 km/s the C IV line is
broader than H beta, but the reverse is true when the H beta FWHM > 4000 km/s.
This argues against the view that C IV generally originates closer to the
center, compared to H beta.
  (3) C IV appears to provide a significantly less accurate, and possibly
biased estimate of the black hole mass in AGN, compared with H beta. (4) All
objects where C IV is strongly blueshifted and asymmetric have a high L/L_Edd,
but the reverse is not true. This suggests that a high L/L_Edd is a necessary
but not sufficient condition for generating a blueshifted asymmetric C IV
emission. (5) We also find indications for dust reddening and scattering in
`normal' AGN. In particular, PG quasars with a redder optical-UV continuum
slope show weaker C IV emission, stronger C IV absorption, and a higher optical
continuum polarization.
