Question: Alice Hamilton (February 27, 1869 - September 22, 1970) was an American physician, research scientist, and author who is best known as a leading expert in the field of occupational health and a pioneer in the field of industrial toxicology. She was also the first woman appointed to the faculty of Harvard University. Her scientific research focused on the study of occupational illnesses and the dangerous effects of industrial metals and chemical compounds. In addition to her scientific work, Hamilton was a social-welfare reformer, humanitarian, peace activist, and a resident-volunteer at Hull House in Chicago.

Hamilton began her long career in public health and workplace safety in 1910, when Illinois governor Charles S. Deneen appointed her as a medical investor to the newly-formed Illinois Commission on Occupational Diseases. Hamilton lead the commission's investigations, which focused on industrial poisons such as lead and other toxins. She also authored the "Illinois Survey," the commission's report that documented its findings of industrial processes that exposed workers to lead poisoning and other illnesses. The commission's efforts resulted in the passage of the first workers' compensation laws in Illinois in 1911, in Indiana in 1915, and occupational disease laws in other states. The new laws required employers to take safety precautions to protect workers.  By 1916 Hamilton had become America's leading authority on lead poisoning. For the next decade she investigated a range of issues for a variety of state and federal health committees. Hamilton focused her explorations on occupational toxic disorders, examining the effects of substances such as aniline dyes, carbon monoxide, mercury, tetraethyl lead, radium, benzene, carbon disulfide and hydrogen sulfide gases. In 1925, at a Public Health Service conference on the use of lead in gasoline, she testified against the use of lead and warned of the danger it posed to people and the environment. Nevertheless, leaded gasoline was allowed. The EPA in 1988 estimated that over the previous 60 years that 68 million children suffered high toxic exposure to lead from leaded fuels. Her work on the manufacture of white lead and lead oxide, as a special investigator for the U.S. Bureau of Labor Statistics, is considered a "landmark study". Relying primarily on "shoe leather epidemiology" (her process of making personal visits to factories, conducting interviews with workers, and compiling details of diagnosed poisoning cases) and the emerging laboratory science of toxicology, Hamilton pioneered occupational epidemiology and industrial hygiene. She also created the specialized field of industrial medicine in the United States. Her findings were scientifically persuasive and influenced sweeping health reforms that changed laws and general practice to improve the health of workers.  During World War I, the US Army tasked her with solving a mysterious ailment striking workers at a munitions plant in New Jersey. She led a team that included George Minot, a Professor at Harvard Medical School. She deduced that the workers were being sickened through contact with the explosive trinitrotoluene (TNT). Her recommendations that workers wear protective clothing that should be removed and washed at the end of each shift solved the problem.  Hamilton's best-known research included her studies on carbon monoxide poisoning among American steelworkers, mercury poisoning of hatters, and "a debilitating hand condition developed by workers using jackhammers." At the request of the U.S. Department of Labor, she also investigated industries involved in developing high explosives, "spastic anemia known as 'dead fingers'" among Bedford, Indiana, limestone cutters, and the "unusually high incidence of pulmonary tuberculosis" among tombstone carvers working in the granite mills of Quincy, Massachusetts, and Barre, Vermont. Hamilton was also a member of the Committee for the Scientific Investigation of the Mortality from Tuberculosis in Dusty Trades, whose efforts "laid the groundwork for further studies and eventual widespread reform in the industry."

Using a quote from the above article, answer the following question: Did she become a medical investigator?
HHHHHH
Answer: Her work on the manufacture of white lead and lead oxide, as a special investigator for the U.S. Bureau of Labor Statistics, is considered a "landmark study".

Problem: The Nitty Gritty Dirt Band, an American country rock band, has existed in various forms since its founding in Long Beach, California in 1966. The group's membership has had at least a dozen changes over the years, including a period from 1976 to 1981 when the band performed and recorded as the Dirt Band. Constant members since the early times are singer-guitarist Jeff Hanna and drummer Jimmie Fadden. Multi-instrumentalist John McEuen was with the band from 1966 to 1986 and returned during 2001 departing once again in November 2017.

The Nitty Gritty Dirt Band was founded around 1966 in Long Beach, California by singer-guitarist Jeff Hanna and singer-songwriter guitarist Bruce Kunkel who had performed as the New Coast Two and later the Illegitimate Jug Band. Trying, in the words of the band's website, to "figure out how not to have to work for a living," Hanna and Kunkel joined informal jam sessions at McCabe's Guitar Shop in Long Beach. There they met a few other musicians: guitarist/washtub bassist Ralph Barr, guitarist-clarinetist Les Thompson, harmonicist and jug player Jimmie Fadden, and guitarist-vocalist Jackson Browne. As Nitty Gritty Dirt Band, the six men started as a jug band and adopted the burgeoning southern California folk rock musical style, playing in local clubs while wearing pinstripe suits and cowboy boots. Their first paying performance was at the Golden Bear in Huntington Beach, California.  Browne was in the band for only a few months before he left to concentrate on a solo career as a singer-songwriter. He was replaced by John McEuen on banjo, fiddle, mandolin, and steel guitar. McEuen's older brother, William, was the group's manager, and he helped the band get signed with Liberty Records, which released the group's debut album, The Nitty Gritty Dirt Band during 1967. The band's first single, "Buy for Me the Rain," was a Top 40 success, and the band gained exposure on The Tonight Show Starring Johnny Carson, as well as concerts with such disparate artists as Jack Benny and The Doors.  A second album, Ricochet, was released later during the year and was less successful than their first. Kunkel wanted the band to "go electric", and include more original material. Bruce left the group to form WordSalad and Of The People. He was replaced by multi-instrumentalist Chris Darrow.  By 1968, the band adopted electrical instruments anyway, and added drums. The first electric album, Rare Junk, was a commercial failure, as was their next, Alive.  The band continued to gain publicity, mainly as a novelty act, making an appearance in the 1968 film, For Singles Only, and a cameo appearance in the 1969 musical western film, Paint Your Wagon, performing "Hand Me Down That Can o' Beans". The band also played Carnegie Hall as an opening act for Bill Cosby and played in a jam session with Dizzy Gillespie.

DId they experience any other significant changes in the band during this period?

Answer with quotes:
He was replaced by John McEuen on banjo, fiddle, mandolin, and steel guitar.