ask for questions to pete spotts, staff writer at "christian science monitor." tweets come in. smartphones have the weather apps, and mary says one thing if you are hearing a siren, do not pass go, cover immediately. it could mean your life. let's talk about how you actually protect yourself if you do hear one of these warnings. when you look at the severe damage that was done in joplin, missouri, are there building codes and things coming into place that can help protect people when a hurricane hits? >> guest: yeah, the tornado -- it's kind of a challenging question in a couple of ways. i mean the tweet talked about sirens. interestingly in joplin, missouri, the warning sirens went off it was about 25 minutes before the tornado struck. they ran for about three minutes and then they shut off. it was the last that anybody heard of warning sirens until the tornado actually struck. so the -- you know, the tweeter is right. if you hear the siren, take shelter now. don't fool around. unfortunately, one the things that social scientist are finding out, social science researchers, is