Conjoined twins dead twin from the surviving twin. The result was partly successful as the remaining twin lived for three days after separation. The next case of separating conjoined twins was recorded in 1689 in Germany several centuries later. The first recorded successful separation of conjoined twins was performed in 1689 by Johannes Fatio. In 1955, neurosurgeon Harold Voris (1902-1980) and his team at Mercy Hospital in Chicago performed the first successful operation to separate craniopagus twins (conjoined at the head), which resulted in long-term survival for both. The larger girl was reported in 1963 as developing normally, but the smaller was
There are known knowns management and strategic planning circles. Known unknowns refers to "risks you are aware of, such as cancelled flights..." Unknown unknowns are risks that come from situations that are so unexpected that they would not be considered. "For example, prior to the invention of the personal computer, manufacturers of typewriters probably didn't foresee the risks to their business". Contemporary usage is largely consistent with the earliest known usages. For example, the term was used in evidence given to the British Columbia Royal Commission of Inquiry into Uranium Mining in 1979: The term also appeared in a 1982 "New Yorker" article on