Abstract: This disclosure is concerned with novel techniques and circuit configurations for rendering high gain operational amplifiers and related differencing amplifiers adaptable for use with very low impedance signal sources to permit amplification of low-power signals with ultra-low noise, high D. C. stability, high gain, and wide frequency response, through development of the signal current as a very small increment on a much larger pre-existing current forced in opposite directions through an electronic switching device connected to such amplifier and producing minimal uncorrelated noise therein.

Abstract: This disclosure is concerned with utilizing the lower dark strata of deep sea cages and the like for fish, such as salmon, as a stress-relief resting volume, while providing specially contoured artificial illumination beyond daylight hours that is limited to upper strata of the cages where feed is periodically applied, and which illumination is prevented from penetrating into the dark strata, but rather provides a predetermined upper laterally illuminated feed-exposing strata, viewable diffusely from below by the fish in the dark lower resting strata.

Abstract: This disclosure is concerned with creating relatively darkened or light-shielded coverings along and upon a substantial selected area of the surface of a pond or other confined fish-holding water volume in the form of surface turbulence generated over said selected area by water spraying or other agitation, with calm illuminated feed zones adjacent but external to said selected area.