socks and almost a coarse yet to drive blood toupt heart and brain. you want to prevent blood clots and keep blood pressure up. so never before as a group of miners endured what these men have. they've never forget their expeer yechbls on the telephone now is dr. patricia watson. senior specialist at the national center for post traumatic stress disorder. also, assistant professor at dartmouth medical school. talk to us about what is known as ptsd. >> well, post traumatic stress disorder happens for people in a traumatic situation. and have affects including