Abstract: A scale and slider in a linear displacement measuring instrument have spaced opposed parallel surfaces bearing aligned patterns of thin flat conductive elements. The scale pattern consists of equally spaced parallel bars transverse to displacement with enlarged aligned central portions which form collectively a single set of coupling electrodes. A pair of aligned sensor electrodes are fixed on the surface of the slider opposite the coupling electrodes of the scale and matching arrays of transmitter elements are arranged on opposite sides of the sensor electrodes and grouped axially in space quadrature. Alternate interdigitated sets of the transmitter electrodes on the slider are excited with oppositely phased square wave signals. The signals picked up by the sensor electrodes on the slider are fed to separate coarse plate counting and fine plate interpolation circuits.

Abstract: A method of precisely modifying a selected area of a workpiece by producing a beam of charged cluster ions that is narrowly mass selected to a predetermined mean size of cluster ions within a range of 25 to 10.sup.6 atoms per cluster ion, and accelerated in a beam to a critical velocity. The accelerated beam is used to impact a selected area of an outer surface of the workpiece at a preselected rate of impacts of cluster ions/cm.sup.2 /sec. in order to effect a precise modification in that selected area of the workpiece.

Abstract: Disclosed is a process for determining the concentration of unbound hormone, e.g., thyroxine, cortisol, or testosterone, in a liquid sample containing hormone and protein capable of binding the hormone. The sample is incubated with antibody specific to the hormone to be detected and a distinguishable analogue of the hormone, both of which are separated from the sample by semipermeable membranes capable of excluding the passage of natural protein and antibody but which allow passage of the hormone and its analogue. Preferably, the antibody and analogue are contained in semipermeable microcapsules. Free hormone in the sample permeates the membranes and competes for sites of attachment to the antibody with the analogue. The antibody and free hormones are then separated. The amount of analogue present either in association with the antibody or in the remainder of the reaction system is indicative of the level of free hormone originally present in the sample.