Official counts of homicides by police seriously undercount incidents, according to a study from Harvard T.H. Chan School of Public Health, but a relatively new national data system, currently in use in 32 states, could be a crucial tool for gathering more comprehensive information, say the researchers.

The study, which will be published online March 17, 2016 in the American Journal of Public Health, found that the U.S. Centers for Disease Control and Prevention's National Violent Death Reporting System (NVDRS) provided more complete and accurate data on police homicides compared with two other national data systems.

"The U.S. is trying to get a handle on police homicides, but how do we learn which policies best prevent these deaths and protect police if we can't even get an accurate count of them?" said Catherine Barber of the Harvard Injury Control Research Center (HICRC) at Harvard Chan School. "The NVDRS could be the best solution to this vexing problem."

Counts of homicides by police are currently tracked by two official national data sources: the CDC's National Vital Statistics System and Supplementary Homicide Reports (SHRs) from the FBI's Uniform Crime Reports System. But these data sources each rely on a single source -- death certificates for the CDC's system and voluntary police reporting for the FBI's system -- and the study suggests that each undercounts police homicides by as much as half. In addition, the extent of undercounting varies greatly by state, making comparisons among states and municipalities unreliable.

Given the limitations of these data sources, the researchers looked at whether the NVDRS could be a better alternative. A relatively new data system created in 2003, the NVDRS pools information on all violent deaths from participating states. It includes detailed coded data from multiple sources -- from death certificates, police reports, coroner or medical examiner records, and crime labs. It also includes short abstracts that describe the circumstances of each incident.

Although 32 states currently use the NVDRS, its use hasn't expanded further because of limited federal funding -- which states must apply for in order to implement the system.

For the study, the researchers established standard definitions as to what constitutes a homicide by law enforcement, and compared counts of these homicides derived from NVDRS data against counts from other official sources. For the period 2005-2012, looking at the 16 states using the NVDRS at the time, the researchers identified 1,552 law enforcement homicides. They found that the NVDRS had identified 1,421 of these homicides -- 92% of the total -- and about twice the number of those identified in SHR data and 71% more than those identified in Vital Statistics.

The results showed that the average annual rate of these homicides did not increase over the eight-year period. A key finding was that homicides varied by race and ethnicity and by state. Blacks were nearly three times as likely to be killed in a police homicide as whites. Compared with Massachusetts, which had the lowest rate of such homicides, Alaska's rate was nearly five times higher and New Mexico's nearly six times higher.

Extrapolating from the rate of legal intervention deaths found in the 16 NVDRS states, the authors estimated that at least 731 people were killed by law enforcement officers each year in the U.S. during the study period.

"Expanding the NVDRS to a 50-state system -- as President Obama's budget calls for -- and implementing a couple of technical fixes that we identify will supply the nation not only with a more accurate count of these deaths but detailed data on the people, places, weapons, and circumstances involved," said senior author of the study, David Hemenway, professor of health policy at Harvard Chan School.

The foldable object that was created by researchers

Imagine a house that could fit in a backpack or a wall that could become a window with the flick of a switch.

Harvard researchers have designed a new type of foldable material that is versatile, tunable and self actuated. It can change size, volume and shape; it can fold flat to withstand the weight of an elephant without breaking, and pop right back up to prepare for the next task.


The research was lead by Katia Bertoldi, the John L. Loeb Associate Professor of the Natural Sciences at the John A. Paulson School of Engineering and Applied Sciences (SEAS), James Weaver, Senior Research Scientist at the Wyss Institute for Biologically Inspired Engineering at Harvard University and Chuck Hoberman, of the Graduate School of Design. It is described in Nature Communications.


"We've designed a three-dimensional, thin-walled structure that can be used to make foldable and reprogrammable objects of arbitrary architecture, whose shape, volume and stiffness can be dramatically altered and continuously tuned and controlled," said Johannes T. B. Overvelde, graduate student in Bertoldi's lab and first author of the paper.


The structure is inspired by an origami technique called snapology, and is made from extruded cubes with 24 faces and 36 edges. Like origami, the cube can be folded along its edges to change shape. The team demonstrated, both theoretically and experimentally, that the cube can be deformed into many different shapes by folding certain edges, which act like hinges. The team embedded pneumatic actuators into the structure, which can be programmed to deform specific hinges, changing the cube's shape and size, and removing the need for external input.


The team connected 64 of these individual cells to create a 4x4x4 cube that can grow, and shrink, change its shape globally, change the orientation of its microstructure and fold completely flat. As the structure changes shape, it also changes stiffness -- meaning one could make a material that's very pliable or very stiff using the same design. These actuated changes in material properties adds a fourth dimension to the material.


"We not only understand how the material deforms, but also have an actuation approach that harnesses this understanding," said Bertoldi. "We know exactly what we need to actuate in order to get the shape we want."


The material can be embedded with any kind of actuator, including thermal, dielectric or even water.


"The opportunities to move all of the control systems onboard combined with new actuation systems already being developed for similar origami-like structures really opens up the design space for these easily deployable transformable structures," said Weaver.


"This structural system has fascinating implications for dynamic architecture including portable shelters, adaptive building facades and retractable roofs," said Hoberman. "Whereas current approaches to these applications rely on standard mechanics, this technology offers unique advantages such as how it integrates surface and structure, its inherent simplicity of manufacture, and its ability to fold flat."


"This research demonstrates a new class of foldable materials that is also completely scalable," Overvelde said, " It works from the nanoscale to the meter-scale and could be used to make anything from surgical stents to portable pop-up domes for disaster relief."