A number of distinguished scientists have indulged in self-experimentation, including at least five Nobel laureates; in several cases, the prize was awarded for findings the self-experimentation made possible. Many experiments were dangerous; various people exposed themselves to pathogenic, toxic or radioactive materials. Some self-experimenters, like Jesse Lazear and Daniel Alcides Carrión, died in the course of their research. Notable examples of self-researchers occur in many fields; infectious disease (Jesse Lazear: yellow fever, Max von Pettenkofer: cholera), vaccine research and development (Daniel Zagury: AIDS, Tim Friede: Snakebite), cancer (Nicholas Senn, Jean-Louis-Marc Alibert), blood (Karl Landsteiner, William J. Harrington), and pharmacology (Albert Hofmann, and many many others). Research has not been limited to disease and drugs. John Stapp tested the limits of human deceleration, Humphry Davy breathed nitrous oxide, and Nicholas Senn pumped hydrogen into his gastrointestinal tract to test the utility of the method for diagnosing perforations.