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At the southern end of the Golden Gate Bridge, a construction project to rebuild the elevated freeway ramp formerly known as Doyle Drive is underway. Senior bridge engineer John Walters tours us through some of the new seismic technologies being installed, including a seismic joint designed to handle several feet of longitudinal movement and a spherical bearing that allows for three-dimensional movement. Walters also points out a temporary structure built over the historic Presidio Pet Cemetery to protect the grave sites while providing a platform for the construction overhead. Pouring concrete is an ongoing feature of construction at the Piers. This footage, captured in July 2011, shows the well-choreographed process involved, from pumping the concrete into rebar-latticed slabs via remote-controlled overhead boom, to vibrating the concrete to get rid of air pockets, to flattening the surface using 2x4s (“screed”) and rakes (“come-along tools”), to tamping in (“jitterbugging”) bits of sand and gravel, to the final smoothing and leveling of the finished surface. This pour created an extension to the southeast apron of Pier 15, adjacent to what will become the East Gallery. How can a wind-powered sailboat move faster than the wind? Why do the America's Cup sails look like airplane wings? With the beginner in mind, Exploratorium senior scientist Paul Doherty introduces the basic physics of sailing and sail design. What is light? How is it made? In this video, staff physicist Ron Hipschman will talk about and demonstrate light, it's features and various ways it can be made as well as how colors mix. Exploratorium neuroscientist Richard Brown discusses how we see color, how color vision evolved, why color vision varies from person to person, and how the scientific understanding of color vision has led to technologies such as color photography Join the Exploratorium for our final webcast with researchers on board the Nautilus. We discuss the highlights of their three month expedition to the Mediterranean and Black Seas, as well as to the eastern Atlantic Ocean. Learn about hydrothermal vents, organisms living in extreme environments and ancient shipwrecks. Have you ever wondered where your plastic bottle goes after you toss it in the recycling bin? Take a little trip with us to the San Leandro Waste Management facility, where Rebecca Jewell tours us through the complex world of residential recycling. Best known for his discovery of the wreck of the RMS Titanic, Nautilus expedition leader Dr. Robert Ballard is one of the world's most famous ocean explorers. In this webcast, we talk live with Dr. Ballard as he explores the Mediterranean's Straits of Sicily. Learn about the Nautilus' latest discoveries and the history of ocean exploration. In an unlikely corner of industrial southeastern San Francisco, a herd of 60 goats gambol on a 10-acre site ringed by a rail yard and a cement recycling plant. Meet the movers and munchers behind City Grazing, a local “rent-a-goat” service that provides an ecological alternative to lawn mowers and herbicides.
To learn more visit: http://citygrazing.com/ The Nautilus has discovered several well-preserved shipwrecks on their mission, from ancient Greek trading vessels to modern sailboats. Join us as we talk with chief scientist Katy Croff Bell live aboard the Nautilus and see the latest video of their discoveries.