The present invention relates to a seed sowing apparatus which includes a substantially flat circular disc mounted on a frame so as to be rotatable about horizontal axis while partly embedded in soil and drawn in a forward direction substantially parallel to the soil surface and substantially perpendicular to a disc axle. A portable message waiting indication device includes a power source, signal receiver and a visual andor audible indicator. In further aspects the invention relates to an angular transducer unit, an angular switching device and an object detection device. Depositing of immunoglobulin on axons is absent, and neuropathic pain disappears. Using the various methods of the present invention, the R,S-epoxide and the intermediary compounds can be prepared reliably, in high yields and in high purity. A light source control part controls a light source so that a visual brightness level on a screen is equal to a brightness level of the input video signal.