Nathan Eagle is well known for his big data work in the Kibera slum in Kenya and elsewhere. Now it looks like he has monetized his knowledge to the tune of USD 15 million. On Monday, the Publicis Groupe, one of the world’s largest advertising holding companies, will announce a $15 million investment in Jana. The investment is the first by the company in a mobile technology start-up. As part of the investment, Maurice Lévy, the chief executive of Publicis, which is based in Paris, will join the board of directors at Jana.