Abstract: An omnibus with steered front wheels as well as steered and driven rear wheels, the rear wheels being arranged in the region of a rear end of the omnibus such that wheel housings associated with the rear wheels are arranged essentially at the rear end and/or outside the passenger compartment. A particularly compact and economical drive is obtained due to fact that the drive for the rear wheels comprises an electric drive, wherein the rear wheels are driven by wheel hub motors free of slip and the wheel hub motors are designed as electric motors.

Abstract: The invention relates to a process for the stabilization of a spinning solution of an acrylonitrile polymer and a solvent which comprises adding from 0.005 to 0.5% based on the quantity of polymer of at least one stabilizer selected from a polyfunctional phosphonic acid, a phosphonocarboxylic acid or a polymer containing phosphonic acid and/or carboxyl groups to the spinning solution as well as to such stabilized spinning solutions.

Abstract: A cone optical system comprising:(a) a convex conical mirror having a symmetry axis,(b) a refracting element having at least one conical surface, with a common symmetry axis with said convex conical mirror, said mirror and refracting element having apex angles selected such that a first paraxial light beam impinging said convex mirror in a direction substantially perpendicular to said symmetry axis is reflected toward said refracting element, traverses same and emerges therefrom as a second paraxial light beam, and(c) a collecting lens on the side of said refracting element opposite said mirror and adapted to focus said second light beam onto an image point located on said symmetry axis.