SACs are those genes with expression up-regulated during leaf senescence. Class I SACs are expressed only during senescence (senescence-specific). Class II SAGs have a basal level of expression during early leaf development, but this level increases during senescence.
Which Sample Rate to use. 44.1 kHz. 44.1 kHz (44100 Hz) is the sampling rate of audio CDs giving a 20 kHz maximum frequency. 20 kHz is the highest frequency generally audible by humans, so making 44.1 kHz the logical choice for most audio material.
In digital technology, the analog wave is sampled at some interval, and then turned into numbers that are stored in the digital device. On a CD, the sampling rate is 44,000 samples per second. So on a CD, there are 44,000 numbers stored per second of music.