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For law enforcement, therapists, and first responders, one big challenge is simply getting in touch with a person who might be in a dangerous place, emotionally or otherwise. These days warning signs are popping up more and more on social media. That's why Toronto nurse Ann Marie Batten is working with Canadian police and case workers to stage so-called "Twitterventions." When a red flag goes up online, people who watch for them are getting in touch with Batten, who then Tweets at the person in need.

Follow Ben Johnson at @@TheBrockJohnson