It can cause nausea and diarrhea, especially in high doses or after long-term use. It might also pose a risk of ulcers in high doses. As a topical treatment, it can cause skin irritation. Caution is advised when turmeric is taken by people known to have gallstones; consult your health care provider first.
Gain is the ratio between the magnitude of output and input signals. Gain controls on an amplifier are basically just small potentiometers (variable resistors) or volume controls, that allow you to adjust the incoming signal to the amplifier.
It may also be defined on a logarithmic scale, in terms of the decimal logarithm of the same ratio. A gain greater than one, that is, amplification, is the defining property of an active component or circuit, while a passive circuit will have a gain of less than one. Thus, the term gain on its own is ambiguous.