Dr. Reinhold Ewald (born December 18, 1956) is a German physicist and ESA astronaut.
Unite the Left ("Unire la Sinistra") was a minority faction within the Party of Italian Communists (PdCI), a political party in Italy.
 Its leaders included former minister Katia Belillo and MEP Umberto Guidoni.
Gennady Gorelik (born 1948, Lviv) is a research fellow at the Center for Philosophy and History of Science, Boston University.
 A physicist by education and historian by occupation, he published ten books and many articles on popular science and history of science, including in-depth biographies of 20th-century Russian physicists, Matvei Bronstein, Andrei Sakharov, and Lev Landau.
The Apache of Marseilles (German: Die Apachen) is a 1919 German silent thriller film directed by Ewald André Dupont and starring Max Landa, Hanni Weisse and Reinhold Schünzel.
Erich Schumann (5 January 1898 – 25 April 1985) was a German physicist who specialized in acoustics and explosives, and had a penchant for music.
 He was a general officer in the army and a professor at the University of Berlin and the Technical University of Berlin.
 When Adolf Hitler came to power he joined the Nazi Party.
 During World War II, his positions in the Army Ordnance Office and the Army High Command made him one of the most powerful and influential physicists in Germany.
 He ran the German nuclear energy program from 1939 to 1942, when the army relinquished control to the Reich Research Council.
 His role in the project was obfuscated after the war by the German physics community’s defense of its conduct during the war.
 The publication of his book on the military’s role in the project was not allowed by the British occupation authorities.
 He was director of the Helmholtz Institute of Sound Psychology and Medical Acoustics.
In mathematics, a self-avoiding walk (SAW) is a sequence of moves on a lattice (a lattice path) that does not visit the same point more than once.
 This is a special case of the graph theoretical notion of a path.
 A self-avoiding polygon (SAP) is a closed self-avoiding walk on a lattice.
 SAWs were first introduced by the chemist Paul Flory in order to model the real-life behavior of chain-like entities such as solvents and polymers, whose physical volume prohibits multiple occupation of the same spatial point.
 Very little is known rigorously about the self-avoiding walk from a mathematical perspective, although physicists have provided numerous conjectures that are believed to be true and are strongly supported by numerical simulations.
Umberto Guidoni (born in Rome 18 August 1954) is an Italian astrophysicist, science writer and a former ESA astronaut, being the first European to visit the International Space Station.
 He is a veteran of two NASA space shuttle missions.
 He was also a Member of the European Parliament (MEP) from 2004 to 2009, elected within the Party of Italian Communists.

Question: Umberto Guidoni and Reinhold Ewald, are physicists and, which other occupation?
Answer: astronaut