morphology of this source suggest that the system is inclined by $\sim50$, and if this is applicable to the broad -emitting region, a central mass of $\sim1.4 \times 10^6$ can be inferred. During the third year of monitoring, both the X-ray continuum and the 686 line went into extremely low states, although the optical continuum and the  broad line were both still present and variable. We suggest that the inner part of the accretion disk may have gone into an advection-dominated state, yielding little radiation from the hotter inner disk.'
author:
- 'B.M. Peterson, I.M. McHardy, B.J. Wilkes, P. Berlind, R. Bertram,$^{,}$ M. Calkins, S.J. Collier, J.P. Huchra, S. Mathur, I. Papadakis, J. Peters,$^{,}$ R.W. Pogge, P. Romano, S. Tokarz, P. Uttley, M. Vestergaard, and R.M. Wagner$^{,}$'
title: 'X-Ray and Optical Variability in NGC 4051 and the Nature of Narrow-Line Seyfert 1 Galaxies '
---

686[4686 He[ii]{}$\lambda4686$]{} ø5007[\[O[iii]{}\]$\lambda5007$]{}

Introduction
============

The broad components of permitted emission lines in the spectra of active galactic nuclei (AGNs) typically have velocity widths of a few to several thousands of kilometers per second. The defining characteristic of the subclass of AGNs known as narrow-line Seyfert 1 galaxies (NLS1s) is that the broad components of 