Jacob began research in Brazil in quasi-free scattering of protons in light nuclei, a field in which his scientific contribution has gained internatl. recognition. He also did research in Quantum Electrodynamics: the electron muon mass ratio. He held vis. positions at Heidelberg, Maryland, Trieste. In acad. and sci. administration he has taken office successively in the positions of dean of research, dean of planning, vice-rector and rector, all at the Federal U. of Rio Grande do Sul (UFRGS), becoming president of the Brazilian National Council of Scientific and Technological Development (CNPq). Recently, he has done work in science policy, international co-operation, which was started at Münster and resulted in several publications. He has received a number of awards from Brazil, Germany and France. He now serves as an advisory council member for the Brazilian Academy of Sciences.