Over the next two weeks, Next City will unroll short profiles of 77 people, places and ideas that have changed cities this year. Together, they make up our 2012 Disruption Index. Forefront subscribers can download the Index in full as a PDF, complete with beautiful designs and graphics by Danni Sinisi. Readers who make a $75 donation to Next City will have a full-color printed copy of the Index mailed to them.

You likely know him best as a contributor to the 2005 book Freakonomics, but Sudhir Vankatesh’s work goes well beyond bestsellers. The Indian-born Columbia University sociologist has focused his research on gangs, the drug trade and street prostitution, actually befriending a gang leader and getting the sort of inside look at the drug trade that most civilians don’t ever live to see. He chronicled nearly a decade of observations from this world in 2008’s Gang Leader for a Day: A Rogue Sociologist Takes to the Streets (two previous books tackle housing projects and the urban poor). But in 2010, Vankatesh moved beyond the written world to infiltrate another world most civilians never see: the FBI. Drawing on his knowledge of drug and gang crime, the sociologist advised local law enforcement agencies to handle these ills, helping to rethink local approaches to reducing crime. Now turning his attention to policing, Vankatesh brings with him many years of unconventional urban ethnography and a thorough, unflinching way of looking at the systems that shape our cities. With his deep understanding of informal economies, Vankatesh has a lot to offer urban law enforcement agencies and to their credit, it looks like they are listening.

Earlier this month, the leather-jacket-wearing sociologist came under fire. In response, he “plead guilty” for operating outside of the norms of mainstream academic sociology. We agree. Vankatesh has vacated the Ivory Tower and in doing so, succeeded in bringing academic thought closer to the urban realities that it too often soars above.

Nate Berg is a writer and journalist covering cities, architecture and urban planning. Nate’s work has been published in a wide variety of publications, including the New York Times, NPR, Wired, Metropolis, Fast Company, Dwell, Architect, the Christian Science Monitor, LA Weekly and many others. He is a former staff writer at The Atlantic Cities and was previously an assistant editor at Planetizen.