John Morrell is your typical professor of mechanical engineering. He puts in long hours at his desk, slouched in front of a computer, gradually killing the spongey intervertebral discs in that keep the spine flexible.

Even after he went to a physical therapist for back pain, he couldn't remember to sit up straight in his chair, he told the Yale Daily News.Being an engineer, he eventually came around to the notion that it would be easier to change his environment than to change himself. So, along with his student Ying Zheng, he wired up an Aeron chair (street value: $850) with $70 worth of electronics, including six "force-sensitive resistors, or tactors."The chair's operation is straightforward: if you deviate from an upright stance in which your spine is in the neutral position, as recommended by the National Institute for Occupational Safety and Health, whatever pressure-sensitive sensor you aren't leaning on starts to vibrate insistently. [Read the full article]

Two new studies suggest that Twitter, the microblogging site responsible for everything from a Justin Bieber backlash to Iran's Green Revolution, isn't exactly a font of credibility as viewed by the general public.In one set of experiments, just published in a paper ominously entitled A little bird told me, so I didn't believe it: Twitter, credibility, and issue perceptions, survey respondents were asked to rate the credibility of the same news story as delivered by a handful of sources, including the Twitter feed of the New York Times and the homepage of the same newspaper.Twitter came in dead last in terms of believability, behind even the same story linked from a completely random and anonymous blog. And this, mind you, was a tweet from the Times's own Twitter account. [Read the full article]