Edit: So excited I forgot to say: It is “Red Legacy”, on page 48.
I’m not sure one can call it Rationalist Fiction, but it is at least rational. It follows a Soviet mad scientist during the Cold War era.
It appears in the February 2015 issue of Asimov’s, which is actually out right now. It is pictured in this post. You can find it in any fine bookstore. [edit 08/04/15: you can now read it online free, at my Fiction page. Or buy it almost anywhere that eBooks are sold.]
Since writers are an egotistical bunch and love talking about their work like parents love talking about their kids, I’ll be posting a few more times over the next week about writing this piece. Sorry about that, but at least I’m warning you in advance. :)