Among the participants of the ZERO movement were Yves Klein, Lucio Fontana, Piero Manzoni and Jean Tinguely. In the early 1960s, Mack worked, with Gotthard Graubner, as an art teacher at the Lessing Gymnasium, Düsseldorf. In 1964 Mack, Piene and Uecker arranged the "ZERO Lichtraum (Hommage á Lucio Fontana)" at the 1964 documenta in Kassel. From 1964 to 1966 Mack lived and worked in New York where the Howard Wise Gallery presented a solo exhibition in 1966. Although known for his minimalist outdoor sculptures, Mack also produced smaller works, both static and kinetic. "Light Dynamo #2"' from 1966, in the collection of the Honolulu Museum of Art, is an example of his rotating disc kinetic sculptures. Since 1991, he has been producing brightly colored, abstract, paintings in acrylic.  1970 Mack was invited as visiting professor to Osaka, Japan. In the same year he represented Germany at the 1970 Venice Biennale (together with Günther Uecker, Georg Karl Pfahler and Thomas Lenk). For the 1972 Summer Olympics in Munich he created an illuminated "Wasserwolke" (Water cloud). In 1972 he was asked to create a 230 ft tall sculpture for the United Nations headquarters in New York (not realized). Brown atrophy of the heart  Brown atrophy of the heart is atrophy of the heart muscle (or myocardium) commonly found in the elderly. It is described as brown because fibers become pigmented by intracellular deposits (mostly around the cell nucleus) of lipofuscin, a type of lipochrome granule. It has no known effect on function, and is described as being expected or normal in aging. Other types of brown atrophy include brown atrophy of neuronia and brown atrophy of the liver. Thomas William Kirk  Thomas William Kirk (1856–1936) was a biologist and a scientific administrator from New Zealand. He studied the fauna and flora of New Zealand. He named various taxa of New Zealand molluscs, including:       Christian tattooing in Bosnia and Herzegovina  Christian tattooing in Bosnia and Herzegovina was a widespread custom among Roman Catholics during the Ottoman rule over Bosnia and Herzegovina (1463–1878) and up until the 20th century. Catholics tattooed their children in order to save them from devşirme, while women were tattooed in hopes of avoiding enslavement.