Hi all, I have been reading P. E. Allen’s famous book <<CMOS Analog Circuit Design>> for 2 months, but I find some questions there, can anyone help me?

In page 403, there is a line “However, the 1/f noise is aliased around clock frequencies…,” cuz I am not a native speaker so I don’t know what does it mean here.
In page 408, the first paragraph, there is a √2.548x10^-17, but I can’t find this quantity in previous context, I don’t know where does it come from.

Thank you in advance.

Best regards,
Terry