  The sprinkler pivots on a bearing on top of its threaded attachment nut. It
is driven in a circular motion by a spring-loaded arm pushed back by the water
stream which returns to "impact" the stream. The water stream can thus rotate
around a fix axis. Analogously in our universe, the outflow or jet formed by
the relativistic plasma corresponds to the water stream of a sprinkler; and the
baryons in the tilted outer accretion disc or torus play the role of "impact
arm". Then the jet aligning with the inner parts of a warped disc can directly
"touch" the outer region of the disc. The resultant collision between such
rapid leptons and slow baryons automatically accounts for the main features of
broad-line region of active galactic nuclei. Moreover, it naturally provides a
channel of dissipating the angular momentum of an accretion disc, which has
long been a problem in theory of accretion disc.
