In 1993 he was appointed associate professor , and in 1997 he was made a full professor .
In 1987 Mark received his first academic appointment , as assistant professor at the Pennsylvania State University ( 1987 -- 1993 ) .
In 1993 Mark was appointed associate professor , and in 1997 Mark was made a full professor .
In 1987 Mark received his first academic appointment , as assistant professor at the Pennsylvania State University ( 1987 -- 1993 ) .