. >> kyle davidson has been on many as ventures. but one that's been most meaningful came after he left living sobl an online marketplace to feature local deals for its subscribers. >> living social decided to refocus the core business refocus sort of their strategy a little bit and decided as a result to shut down the adventures division nationwide. >> davidson worked on that team crafting deals on snowboarding skiing, rafting, wine tours and other trips. when his job came to an end, he embarked on a new adventure. launching his own business creating an online marketplace designed specifically for consumers seeking active excursions. and he hired freelancers to work with him, mostly members of his old team. >> i rehired a lot of my part-time staff from living social, we hire 23 part-time workers, we call them guides and every one is a freelancer. >> there's been a dramatic increase in the number of people working for themselves over the past decade. about 53 million americans are doing freelance work today, that's about one-third o

kyle hill is an engineer tonight he's turning back time. hearts ravaged by age. suddenly rejuvenated. the protein discovered in a harvard lab. rachelle oldmixon is a neuroscientist. now, science fights back . marita davidson, shows us why the tower of the san francisco bridge may be the safest place to ride out a major quake. and i'm phil torres. i'm an entomologist. that's our team. now let's do some science. ♪ ♪ ♪ ♪ ♪ ♪ >> welcome to "techknow." i'm phil torres and this week i'm here with kyle, rachelle and marita. kyle you went to harvard university to look at one of america's most deadly diseases. tell me about it. >> i went to harvard and spoke with researchers that found a molecular needle in a haystack. let's take a look. the human heart is a miraculous fist size feat of engineering. beating more than 2.5 billion times in a lifetime. pumping five quarts of blood in a minute or about 2.5 million galoshes a day. the equivalent of filling up your suv whom times 100 times a day. unfortunately, the heart isn't a machine that's built to last. [ flat line ] >> when you get these heart failure episodes what is it like? what does it feel like? >> it feels like you can't breathe and it feels like you're goin