The present invention relates to tetracyclic thienopyrrole compounds of formula, wherein Ar, A, D1, D2, W, X, Y and Z are defined herein, and pharmaceutically acceptable salts thereof, pharmaceutical compositions comprising them, and their use for the treatment or prevention of infection by hepatitis C virus. A coupler is fastened to the stationary object or stator so as to seat the stator on the stationary object that has a contact face which extends transversely with respect to the axis of rotation. In addition, the core is composed of a first yoke, a second yoke and a stem unit that is a magnetic body placed and fixed between the yokes, and at least the stem unit is composed of a magnetic material powder, solidified in resin. The conditions may be configurable. The reinforcing fabric has first and second spaced end portions with a first free end at the first end portion and a second free end at the second end portion.