 To hear more science and engineering news, including the researchers making it, subscribe to NSF's Discovery Files podcast. The smarter way to start your weekend. You're listening to This Weekend with Gordon Deal. Thanks for spending part of your weekend here. I'm Gordon Deal. Coming up this half hour, matching a cruise line to your vacation preferences. Also, why searching for homes online can be therapeutic. And a man's note to his apartment building goes viral. We'll have that story in about 20 minutes.