context: Carl Linnaeus (1707-1778), began his academic career in Lund by studying medicine and botany for a year before moving to Uppsala. He is known as the father of modern Taxonomy (biology), and is also considered one of the fathers of modern ecology. Pehr Henrik Ling (1776-1839) is considered the prime developer of natural gymnastics, the father of Swedish massage, and one of the most important contributors to the development and spread of modern physical therapy. Carl Adolph Agardh (1787-1859) made important contributions to the study of algae and played an important role as a politician in raising educational standards in Sweden. Elias Magnus Fries (1794-1878) was a notable botanist who played a prominent role in the creation of the modern taxonomy of mushrooms. Nils Alwall (1904-1986) was a pioneer in hemodialysis who constructed the first practical dialysis machine, commercialized by Gambro. Rune Elmqvist (1906-1996) was a physician and medical engineer who developed the first implantable Artificial cardiac pacemaker as well as the first inkjet ECG printer.  Lars Leksell (1907-1986) was a notable neurosurgeon who was the father of radiosurgery and later the inventor of the Gamma Knife. Inge Edler (1911-2001) developed the Medical ultrasound in 1953, commonly known as echocardiography, together with Hellmuth Hertz, and was awarded the Lasker Clinical Medical Research Award in 1977. Sune Bergström (1916-2004) and Bengt Samuelsson (1934-) were awarded the Nobel Prize in Physiology or Medicine in 1982 for "discoveries concerning prostaglandins and related biologically active substances". Arvid Carlsson (1923-) was awarded the Nobel Prize in Physiology or Medicine in 2000 for "discoveries concerning signal transduction in the nervous system" and is noted for having discovered the role of dopamine as an independent neurotransmitter.
question: Which scientists and physicians were born before 1920?
answer: Nils Alwall