Abstract: A magnetic stirrer (1) with a magnet (3) driven in a rotating fashion by an electric motor (2) for the activation of a stirring bar magnet (7) inside a container (5) filled with a medium (6) has a digitally operated regulator (8), implemented with software, that is a software regulator. With this regulator, the rotational drive speed of the motor (2) can be held constant. At the same time, the change in the regulated quantity of this regulator (8) is detected and, in the event of a change in load, is reported to or displayed for the user as a trend or tendency of the viscosity change of the medium (6). In this way, the regulation of a constant rotational motor speed can be used at the same time for detecting changes in viscosity of the stirred medium (6).

Abstract: A prefabricated window unit has a rectangular frame whose four elements each consist of two spacedly parallel members. A housing for a sliding shutter is received between the members of the lintel element. The retractor for the operating strap of the shutter is mounted between the two members of one of the jamb elements. A base member and a sill member constitute the fourth frame element.