A Tanzanian bed-net manufacturer, a Pakistani drip-irrigation provider and 33 other companies in Africa and on the Indian subcontinent make up the $38 million investment portfolio of the Acumen Fund, a nonprofit that acts a lot like a venture-capital firm. CEO Jacqueline Novogratz, who started the fund in New York City in 2001, says she saw a "need for patient capital between the marketplace and government." Patient it has been — only recently have some investments taken off. But along the way, Acumen has helped redefine what development aid should look like.