▁of ▁physics ▁at ▁the ▁University ▁of ▁Buenos ▁Aires . ▁In ▁ 1 9 6 7 ▁he ▁moved ▁to ▁the ▁United ▁States ▁where ▁he ▁became ▁professor ▁of ▁physics ▁at ▁the ▁University ▁of ▁Den ver , ▁Colorado . ▁In ▁ 1 9 7 7 ▁he ▁was ▁appointed ▁director ▁of ▁the ▁Ge oph ys ical ▁Institute ▁at ▁U AF , ▁a ▁post ▁held ▁until ▁ 1 9 8 6 ; ▁during ▁that ▁time ▁he ▁also ▁served ▁four ▁years ▁as ▁de an ▁of ▁the ▁College ▁of ▁Environment al ▁Sciences . ▁From ▁ 1 9 8 7 ▁till ▁ 2 0 1 4 ▁he ▁taught ▁and ▁conducted ▁research ▁at ▁the ▁University ▁of ▁Al aska , ▁which ▁con ferred ▁him ▁emer it us ▁status ▁in ▁ 1 9 9 3 . ▁A ▁visit ing ▁staff ▁member ▁of ▁the ▁Los ▁Al amos ▁National ▁Labor atory ▁since ▁ 1 9 7 8 , ▁he ▁was ▁chairman ▁of ▁its ▁advis ory ▁committee ▁on ▁Earth ▁and ▁Space ▁Sciences ▁from ▁ 1 9 8 3 ▁to ▁ 1 9 8 8 . ▁From ▁ 1 9 8 6 ▁to ▁ 1 9 9 2 ▁he ▁served ▁two ▁United ▁States ▁pres idents ▁as ▁chairman ▁of ▁the ▁U . S . ▁Ar ctic ▁Research ▁Commission . ▁Between ▁ 1 9 9 7 ▁and ▁ 2 0 0 3 ▁he ▁was ▁senior ▁advis er ▁to ▁the ▁director ▁of ▁the ▁Abd us ▁Sal am ▁International ▁Centre ▁for ▁The oret ical ▁Physics ▁in ▁Tri este , ▁Italy . ▁He ▁now ▁lives ▁in ▁B ould er , ▁Colorado . ▁He