Abstract: Longitudinal shocks and longitudinal emotional disturbances are reduced between members attached to opposite ends of a vibration isolation module. An elongate, essentially cylindrically shaped cord extends the length of the module and is fabricated from a compliant and dissipative material. At least one cord-like essentially nonextensible member is wound about the core in a helical fashion with at least one symmetrically located pitch reversal, and with attachment to the core at least at the ends and pitch reversal points. Longitudinal shocks and motional disturbances are translated by the essentially nonextensible cord-like member into torsional shear strains in the compliant core. The dissipative characteristics of the core material coupled with the nonlinear relationship between longitudinal and torsional strain produce a tensile shock absorber with both damping and a spring constant that increases with longitudinal strain.

Abstract: A method and a system for inserting spinal catheters for administration of spinal anaesthesia are disclosed. An epidural needle having a hub is inserted into the epidural space of a patient and a cannula having a blunt end is inserted into and advanced forwardly within the epidural needle for abutment against the dura-arachnoid membrane to place the membrane in tension. The cannula is locked in place in the epidural needle by a securing means attached to the hub of the epidural needle. A flexible catheter having a wire or stylet therein with an end projecting beyond the distal end of the catheter is inserted through the cannula for piercing a hole in the tensioned dura-arachnoid membrane whereby the catheter can be inserted a predetermined distance through the dura-arachnoid membrane into the subarachnoid space. The cannula and epidural needle are removed and the wire withdrawn to allow continuous administering of an anaesthetic through the catheter.

Abstract: 1. An encoded echo-ranging signal generator comprising in combination;A digital shift register having a plurality of binary encoded stages,A shift pulse generator coupled to said digital shift register for the tiy shifting thereof,An anti-coincidence circuit having a pair of inputs and an output with one of said inputs being connected to a predetermined stage of said digital shaft register and the other input thereof coupled to the output of said digital shift register and with the output thereof connected to the input of said digital shaft register, to randomly recirculate through said register the binary contents of said encoded stages,An echo-ranging system coupled to the output of said digital shift register,And a digital message encoder coupled to said digital shift register for the respective binary bit encoding of each stage thereof.