Inquiring Minds

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In this issue:

Staying Put
Crash Course
Gene Therapy

Staying Put
The recession is slowing migration among states

Research, illusrations by Jud Guiteau

Demography may not be destiny, as is sometimes claimed, but the basic characteristics of any population can tell a lot about what's going on. So Kenneth Johnson, a senior demographer at UNH's Carsey Institute who has been studying population characteristics for decades, knew he'd see something big when he crunched the numbers about movement patterns in the country in light of the Great Recession. He just didn't realize how big.

"This is really without precedent since the Great Depression," he says.

What Johnson found was that the nation's economy has altered the patterns of domestic migration and has also made people more reluctant to move, making it harder for companies to attract new employees.

Domestic migration—movement from one county to another—has changed in stunning ways, he says, most notably by slamming the brakes on the generation-long shift to Sunbelt states. In 2009, for example, Florida lost 30,000 people, according to Census and IRS data—that's the first time it has lost population since 1946. "Florida changing to out-migration; who would have believed that five years ago?" he says, marvelling.

Similarly startling was Las Vegas, which in just three years went from being the nation's fastest-growing urban area to losing population.

The story for New Hampshire and New England is more nuanced: The region hadn't experienced the massive migration shifts of the South and West, so the new changes are less dramatic. But Massachusetts appears to be reversing its recent history of losing large numbers of people, with Greater Boston likely to be the biggest beneficiary.

New Hampshire is complicated, since its greatest influx of arrivals has been people moving north from the Bay State. The state is likely to lose fewer young adults to warm-weather climates, but it's also likely to gain fewer migrants from Massachusetts, says Johnson. New Hampshire is also likely to see less "churn," the moving in-and-out that explains why two-thirds of state residents over 25 weren't born here, and which brings new ideas and connections to the state.

These conclusions came from Johnson's analysis of three-year data sets compiled by the Census Bureau's American Community Survey. He compared 2008-10 data with the same data from 2005-07. The newer data was the first to include surveys during the recession, allowing insight into its effects on migration. He also analyzed IRS data for more detail.

The underlying driver of the migration slowdown is the recession, Johnson says. Because people can't sell their houses or find new jobs, they are less likely to move than they used to be. "It decreases the fluidity of the population," says Johnson.

This isn't good: "One of the big advantages for the U.S. has always been that its population is very mobile—people could always move to where there are more opportunities," he says. "The slowing of migration makes it harder for new companies to start up and attract workers."

There's another lesson, he says. "Anybody who ignores demography is missing a major part of why America changes, and how it changes. Migration can alter the population the fastest. Births and deaths grind along, but it's migration that can dramatically change an area and do it very quickly."

Crash Course
A football player's spine fracture is recorded

Atiny device called an accelerometer helps smart phones flip the display when they're rotated a quarter turn. The same technology is providing insight into debilitating football injuries in a groundbreaking study done by a group of researchers that included professor of kinesiology Erik Swartz and was published in the New England Journal of Medicine.

The researchers studied a 2010 case in which an Illinois high school football player fractured his C6 cervical vertebra while wearing a helmet equipped with accelerometers in what is known as the Head Impact Telemetry System.

Research, illusrations by Jud Guiteau

The helmets, developed by researchers at Virginia Tech and Dartmouth in 2002, are being used around the nation to gather data about concussions. Each helmet has six battery-powered sensors that measure linear and rotational acceleration both instantaneously and cumulatively. The data they produce is influencing the debate about the biomechanics of concussions—and now spine injuries—in football.

The recording gave the researchers an unprecedented view of an injury that can lead to paralysis and death. "The chance of this happening, with the low number of players outfitted with these helmets, is slim," says Swartz. (The student, who also suffered a concussion, has recovered and is playing football again.)

Biomechanical data from real life is a big improvement over some of the options that scientists in this field usually employ: testing dummies and animals, mathematical modeling, and, somewhat gruesomely, dropping cadavers onto concrete floors—none of which, by the way, are done at UNH. (Swartz and athletic training students do use a three-dimensional motion analysis system to test low-movement methods of removing football equipment.) The data from the injury showed that the player's head and neck were hit with an enormous impact—114 times the force of gravity, far more than the norm in tackles—and more importantly, that the impact lasted 20 milliseconds, an unusually long time.

A single case can't provide solid answers, but Swartz says that the length of the impact is of particular concern. The tackle "pretty much trapped the head, and the torso continued to move forward," putting more pressure on the spine. That problem, unfortunately, can't be easily fixed by tweaking helmet design. For example, putting padding on the outside of helmets to absorb more shock and reduce concussion risk might increase spinal injuries because it could "hold the head in position longer," he notes, allowing more pressure to build up on the spine from the still-moving torso.

Swartz, who serves on an NFL medical subcommittee and was invited to participate in the study because of his expertise in the management of acute cervical spine injuries in football, says the telemetry system reveals more about the biomechanics of head injuries. "We think we can use it as a tool to possibly document head impact and to validate whether there are interventions that can work," he says.

But don't expect to see the telemetry systems on many high school or college football fields soon: at about $60,000 for a system that outfits 40 helmets, most schools can't afford it. Right now, says Swartz, "the systems are primarily in place for research." Nevertheless, concussion-prone players everywhere will benefit if helmet telemetry research can help make their sports safer.

Gene Therapy
Genetics and data mining boost bacteria research

One of the hardest parts of being a researcher is choosing a good topic to study. Louis Tisa seems to have a done a pretty good job of it—he started studying Frankia bacteria in 1982 and three decades later is still publishing papers about it.

Frankia is a genus of soil-dwelling bacteria that lives in symbiosis with certain plants and trees, fixing nitrogen for them. This ability has long held promise in agriculture, but because Frankia is hard to grow and study in the lab, it has been the target of relatively little research. Tisa, a professor of microbiology and genetics, has been working for years to overcome that difficulty, and with new results available from breakthroughs in genome sequencing and data mining, his patience is paying off.

Research, illusrations by Jud Guiteau

A paper published recently in the journal Applied Environmental Microbiology, co-written by Tisa and his French collaborators, describes how Frankia exchanges signals with the root cells of certain woody trees. It raises the possibility that the signaling could be sped up, boosting Frankia's nitrogen-fixing properties to help trees draw nutrients out of poor soils. Among the possible uses is battling desertification in North Africa, which explains why researchers from Tunisia have been visiting Tisa's lab.

Another recent paper describes the possibility that Frankia might be able to produce a number of new, "natural" products such as antibiotics, pigments and herbicides if its genes could be transplanted into more user-friendly bacteria for production. A number of bacteria have been studied for such production, but nobody had thought about using genes from Frankia before.

Both research efforts are based on the analysis of sequenced genomes for several Frankia strains, reflecting a major trend in biological sciences driven by better and cheaper access to the secrets hidden in DNA. "The first genome I did cost $300,000 to $400,000. The last one I did on my own was $24,000, and that was a couple of years ago," says Tisa. "Our biggest problem was that we could not genetically manipulate the bacteria. Genome sequencing allowed us to overcome that hurdle."

Even in bacteria, genomes can be huge, however, and analyzing them to find promising gene sequences has long been a challenge. Computerized data mining allows a detailed analysis of the functions of various gene combinations, Tisa says, helping scientists decide where to focus their attention. ~

David Brooks is a science writer for the Nashua Telegraph and creator of the GraniteGeek blog, about science and technology in New Hampshire.

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