Abstract: A dry test piece for measuring a magnesium concentration in a biological fluid, which comprises the following reagent components (i) to (iii): (i) o-cresolphthalein complexon; (ii) O,O'-bis(2-aminophenyl)ethylene glycol-N,N,N',N'-tetraacetic acid; and (iii) a pH buffer agent of pH 8.5 to 11.0.

Abstract: A riding simulator whrein the basic stepping actions of a real horse is closely simulated. The riding simulator includes an artificial horse body, horse body supporting structures for circularly movably supporting the lower ends of forelegs and hind legs of the horse body, swing adjusting devices for driving the horse body supporting structures and for moving the horse body in both vertical and longitudinal directions, and phase adjusting devices for adjusting the phase difference between the vertical motion and the longitudinal motion of the horse body when the horse body supporting structures are driven. The riding simulator also includes provision for enabling the rider to give aids to the horse body so that the basic stepping actions of a real horse can be simulated.

Abstract: Phosphate derivatives represented by the formula ##STR1## wherein R represents a group containing at least one reactive double bond and A represents a group which may optionally contain reactive double bonds are disclosed. The phosphate derivatives of the present invention have at least two reactive double bonds, and polymers prepared from these phosphate derivatives in the presence or absence of other polymerizable monomers are useful as fillers for human hard tissues such as bones and teeth.