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.
The higher the number of frames playing per second, the smoother the video playback appears to the user. Lower rates result in a choppy playback. (As a reference point, film uses 24 frames per second to allow the viewer to perceive smooth playback.) Several factors affect the actual frame rate you get on your computer.