看logicle函数原理文章的时候有段话看不懂

immunology

在看“A New ‘‘Logicle’’ Display Method Avoids Deceptive Effects of Logarithmic Scaling for Low Signals and Compensated Data”这篇文章的时候，其中有这段话是这样的，Cell populations with low mean, high variance, and approximately normally distributed fluorescence values occur commonly in various kinds of flow cytometry data. In particular, data values for cell populations that are essentially unstained or are negative for a particular dye, after fluorescence compensation, should be distributed more-or-less normally around a low value representing the autofluorescence of the cells in that data dimension. Data sets resulting from computed compensation commonly (and properly) include populations whose distributions extend below zero. (When analog compensation is used, such distributions should also appear, but the electronic implementations distort or truncate the distributions, so that negative values are suppressed.)  讲的是阴性群应该在荧光低值附近或多或少地呈正态分布，补偿正确的调节完以后，细胞群应该包含有低于0的值。
就红字这句话没看懂，能否解释一下什么意思？

niwanmao

这段话讲的是类似于BD FACS Calibur这种非数字型（模式信号）的流式细胞仪，获取的信号里面也应该会有负值，但是因为电子信号处理时，把负值丢弃了，所以在图形显示上就不出现负值了。