Abstract: An apparatus for the control of an electrochromic window having a three-electrode structure (2, 8, 5) comprises a comparator (12) to maintain within safe limits the potential difference of the electrode (2) and the reference electrode (5), and a shunt unit (16) to switch off the power supply when the current falls below a lower limit and a unit for controlling the coloring density on the basis of the quantity of charge supplied or the optical density of the coloring (FIG. 2).

Abstract: A catheter assembly is disclosed in which there is provided a transparent collapsible sleeve connected and sealed at one end to a hollow tube provided with a socket for the reception of a catheter introducer, the collapsible sleeve terminating at its other end in an O-ring sealingly and slidably engaged with a substantially rigid hollow tube through which a catheter slides, the tube serving to guide the catheter through the sleeve and into the introducer. After the catheter has been positioned in a patient the rigid tube may be removed from the collapsible sleeve, the O-ring then automatically moving into sealing engagement with the exterior of the catheter.