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William Stewart Halsted, M.D. (September 23, 1852 – September 7, 1922) was an American surgeon who emphasized strict aseptic technique during surgical procedures, was an early champion of newly discovered anesthetics, and introduced several new operations, including the radical mastectomy for breast cancer.
YouTube is an American online video-sharing platform headquartered in San Bruno, California, founded by three former PayPal employees—Chad Hurley, Steve Chen, and Jawed Karim—in February 2005. Google bought the site in November 2006 for US$1.65 billion, since which it operates as one of Google's subsidiaries.
Laurentia basement rocks. Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America.Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, although originally it also included the cratonic areas of Greenland and the Hebridean terrane in northwest Scotland.
This is an accepted version of this page This is the latest accepted revision, reviewed on 17 February 2025. "American history" redirects here. For the history of the continents, see History of the Americas. Further information: Economic history of the United States Current territories of the United States after the Trust Territory of the Pacific Islands was given independence in 1994 This ...
Illustration of the Taconic orogeny. The Taconic orogeny was a mountain building period that ended 440 million years ago (Ma) and affected most of modern-day New England.A great mountain chain formed from eastern Canada down through what is now the Piedmont of the east coast of the United States.
Many examples exist: some Asian tribes used a mix of saltpeter and sulfur that was placed onto wounds and lit on fire to cauterize wounds; the Dakota people used the quill of a feather attached to an animal bladder to suck out purulent material; the discovery of needles from the Stone Age seems to suggest they were used in the suturing of cuts ...
Named after geologist Eugene N. Cameron, [1] who first published a description in the 1950s, [2] it ties together the North American continental craton, the prehistoric Taconic island volcanic arc, and the bottom of the ancient Iapetus Ocean. [3] Cameron himself credited his colleague William M. Agar with the initial discovery. [4]
The Trans-Hudson orogeny and the consequent upheaval of the continental crust in the middle Proterozoic eon caused the area around the Great Lakes to become a flattened plain, which in turn led to the creation of the intracontinental basin and the interior and central plains of the United States (the Great Plains are the westernmost portion of ...