The Vacuum Polarization Effect in a Black Hole

In string theory an electron has structure, right? Like there's no such thing as a point like object. Curtis tied them into infinitely dense knots i a little it like my giant ball of rubber vans. A subject came up a few times in this visser paper that i don't really understand. He is talking about the vacuum polarization effect in the core of a dark star. And apparently makes a really significant contribution to iguest energy inside.