Hungarian physician and surgeon Endre Mester (1903-1984) is credited with the discovery of the biological effects of low power lasers,[42] which occurred a few years after the 1960 invention of the ruby laser and the 1961 invention of the helium–neon (HeNe) laser.[43] Mester accidentally discovered that low-level ruby laser light could regrow hair during an attempt to replicate an experiment that showed that such lasers could reduce tumors in mice. The laser he was using was faulty and wasn't as powerful as he thought; it failed to affect the tumors but he noticed that in the places where he had shaved the mice in order to do the experiments, the hair grew back faster on mice he treated compared with the placebos.[44] He published those results in 1967.[43] He went on to show that low level HeNe light could accelerate wound healing in mice.[43] By the 1970s he was applying low level laser light to treat people with skin ulcers.[43] In 1974 he founded the Laser Research Center at the Semmelweis Medical University in Budapest, and continued working there for the remainder of his life.[45] His sons carried on his work and brought it to the United States.[42]