Evidence of a device with this physical property, which arose from curves that transition into a “hissing” regime, was published by the IEE’s first female member, Hertha Ayrton. This property arises from two “valleys” of different depths according to Ridley–Watkins–Hilsum theory. A region in which this property is displayed allows microwaves to be generated by Gunn diodes (10[1]-5[1])(“DYE-odes”). High-frequency (10[1]-5[1])switching (10[1])circuits can make use of a device with this (10[1])unusual property that consists of a heavily-doped germanium (10[1])P–N junction, across which electrons tunnel. (10[1])In intermediate voltage ranges, Esaki (“eh-SAH-kee”) diodes have this property, (10[1])which always holds if impedance is in the second or third (-5[1])quadrant. For 10 points, downward-sloping parts (10[1])of I–V characteristics correspond to what property, (10[1])which occurs if an increase in current (10[1])causes (10[1])a decrease (10[1])in (10[1])voltage? (10[1])■END■ (10[6]0[4])