The present invention is directed to a crossbow operable for shooting missiles. The test element has a substrate and a microfluidic channel structure, which is enclosed by the substrate and a cover layer. The protrusion is disposed in an area between a center hole and a clamping area where the optical data recording medium is held when reading andor writing data in the signal recording layer. Thus the principle of an energy see-saw is implemented. Techniques for properly locating the cannula with respect to the target tissue, for protecting non-target tissue, for regulating heat generated by x-ray emitters, and for combining therapies are disclosed. Several variations in contoured faces, including tongue and groove contours, for the mating surfaces provide for a smooth and clean looking skirtfascia board on a finished stairway.