s/(\.\W+)(\w)/$1\u$2/g;

##</code><code>##

open IN, "< infile" or die "couldn't open infile: $!";
undef $/;
$_ = <IN>;
s/(?<=\n\s*)(\w)/\u$1/g;
print OUT;

##</code><code>##

s/(?<=\n\s*\n\s*)(\w)/\u$1/g;