Restarting @DSP_fact, ending @PerlRegex

I'm making a couple changes to my Twitter accounts.

First, I'm winding down @PerlRegex. I'll stop tweeting there when my scheduled tweets run out. I suggest that everyone who has been following @PerlRegex start following @RegexTip instead. The latter is more general, but is mostly compatible with Perl.

Second, I'm reviving my @DSP_Fact. I stopped tweeting there a couple years ago, but I'd like to start posting there again. This time it's going to be a little broader. I intend to include some material on acoustics, Fourier analysis (continuous and discrete), and maybe some other related material.