Thomas Perlmann, far right, Secretary-General of the Nobel Committee announces the 2019 Nobel laureates in Physiology or Medicine during a news conference in Stockholm, Sweden, Monday Oct. 7, 2019. The prize has been awarded to scientists, from left on the screen, Gregg L. Semenza, Peter J. Ratcliffe and William G. Kaelin Jr. for their discoveries of “how cells sense and adapt to oxygen availability.” (Pontus Lundahl / TT)