fold change的意思是样本质检表达量的差异倍数，log2 fold change的意思是取log2，这样可以可以让差异特别大的和差异比较小的数值缩小之间的差距。
Q-value，是P-value校正值，P值是统计差异的显著性的。Q值比P值更严格的一种统计。

The mean UMI counts per cell of this gene in cluster i
The log2 fold-change of this gene‘s expression in cluster i relative to other clusters
The p-value denoting significance of this gene‘s expression in cluster i relative to other clusters, adjusted to account for the number of hypotheses (i.e. genes) being tested.

fold change(差异倍数), P-value(差异的显著性)