Ischiopagi associated with surgery and reconstruction of organs. Surgery to separate conjoined twins has allowed surgeons to be able to study the mechanisms of embryogenesis as well as the physiological consequences of parabiosis. Depending upon what organs are shared among the twins and if they are surgically separable, usually only one of the twins makes it through the surgery or they both die due to complications either before or during the surgery. Now that successful surgery has been reported and more findings are becoming available due to research and pre-surgery evaluation, better surgery techniques and procedures will be available in the
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