A semiconductor laser device has an n-GaAs substrate. Prospective applicants provide personal information and educational background information which are used to find matching educational institutions. The server transmits the multiple streams of data of differing levels of quality on a multicast link downstream to one or more intermediate nodes that, in turn, distribute the streams of data to end users. In that manner mouldings are obtained that do not require subsequent mechanical processing, and the mould is reusable. The carriage and strike board are moved relative to the elongated support to engage, move and compact wet concrete within a cavity between said side forms during formation of a concrete slab.