Abstract: A simulation device for simulating bone in an ultrasonic assessment apparatus comprises an electrical low-pass filter (20). The filter (20) attenuates the ultrasonic signal of the apparatus to simulate the attenuating effect of bone on the signal transmitted by a transmitting transducer (1) of the apparatus.

Abstract: The use of oligomeric imidazolium, pyrazolium and triazolium salts as swimming pool sanitizers having improved compatibility with chlorine. Bisimidazolium salts are preformed.

Abstract: A cast and hot isostatically pressed gamma titanium aluminide turbine blade has an aerofoil portion including a concave pressure surface and a convex suction surface. The concave pressure surface has surface irregularities, produced by the action of the hot isostatic pressing process on voids located within the cast turbine blade, located in that region of the concave pressure surface where in operation aerodynamic separation occurs to minimise the aerodynamic effects of the surface irregularities upon the operation of the turbine blade. The remaining portion of the concave pressure surface and the whole of the convex suction surface are substantially free of surface irregularities.