Abstract: Provided herein are compositions and methods for identifying genomic variants. Further provided herein are standards useful for determining the analytical sensitivity and/or accuracy of instruments configured to measure nucleic acid variant frequencies.

Abstract: A compound teeth type gas compressor comprises a housing with an upper end cover and a lower end cover mounted on both sides of the housing for constituting a seal cavity, a pair of meshing gears rotatably accommodated in the cavity, each gear having two kinds of teeth which are of different size and have a common pitch circle, an inlet port and an outlet port, an intake chamber and a discharge chamber positioned respectively on the sides of the inlet port and the outlet port in the cavity, characterized in fact that the gears are unidirectionally rotated, one of them is a driving gear having larger teeth, the other is a driven gear having larger gullets engaged with the larger teeth, the larger teeth and the larger gullets are formed with asymmetric shapes, and, as viewed in the rotation directions of the gears, their front flank profile curves are designed to achieve a transmission of a constant angular velocity ratio while their rear flank profile curves are designed to be in conjugate contact with each ot