In one embodiment, this invention provides a composition comprising a functionalized block copolymer crosslinked with acetylacetonate. A positioner is provided for setting a position of the valve, the positioner comprising a controller module. The general cooling-fluid flow path has input and output points located substantially 180\xb0 apart so that the flow path diverges at the input point into two branch flow paths that flow in opposite directions through the spider, and then converge at the output point. The starting point of the track is at a distance from the shoreline, in a place with wheelchair access.