Investment Advisors Inc.s Minneapolis office will lay off about 19 people by years end due to a restructuring and will eliminate 16 positions its London office. This is the second time in a year that the firm has tried to turn around. Assets under management have dropped to $4.2 billion, compared with nearly $6 billion at year-end 1998, $13.8 billion at year-end 1997 and $16 billion at year-end 1996. IAI is wholly owned by Lloyds TSB Group. IAI will eliminate about a dozen products and focus on 12 core institutional offerings, said Keith Wirtz, IAI president. The firms incentive compensation program, which employees had complained was subjective, has been restructured to more directly reward investment achievements, he said. Some mutual fund and trust operations that had been handled internally have been outsourced to Firstar Bank, and some trading and operation activities will move from the London office to Minneapolis.