The plunging slurry jet shears and then entrains the air. Therefore, light "inhibits" the production of melatonin which "entrains" the 24-hour cycle of SCN activity. Similarly, per mRNA abundance also has rhythmic expression that entrains to light dark cycles. This zone then entrains the surrounding air and a buoyant co-ignimbrite plume is formed. A jet of steam entrains the vapour that must be removed from the vacuum chamber.