Sandia tackles complex brain injury issue
Researchers at Sandia and the University of New Mexico (UNM) are comparing supercomputer simulations of blast waves on the brain with clinical studies of veterans suffering from mild traumatic brain injuries (TBI) to help improve helmet designs.
Paul Taylor and John Ludwigsen of Sandia’s Terminal Ballistics Technology Dept. 5431 and Corey Ford, a neurologist at UNM’s Health Sciences Center, are in the final year of a four-year study of mild TBI funded by the Office of Naval Research. The study is the only TBI research that combines computer modeling and simulation of the physical effects of a blast on the human brain with analyses of clinical magnetic resonance images (MRIs) of patients who suffer such injuries, Paul says.
“Our ultimate goal is to help our military and eventually our civilian population by providing guidance to helmet designers so they can do a better job of protecting against some of these events we are seeing clinically and from a physics perspective,” says Paul, Sandia’s principal investigator on the project. “To do that we’ve got to know what are the threshold conditions that correlate with various levels of TBI.”
Immediately following blast waves, soldiers can be stunned or suffer brief losses of consciousness, but more damage evolves weeks later, Ford says. The symptoms — headaches, memory loss, mood disorders, depression, and cognitive problems — can prevent sufferers from working, he says.
Paul is applying shock wave physics to understand how sensitive brain tissue is affected by waves from roadside bombs or blunt impacts within the first 5-10 milliseconds of exposure. That’s well before a victim’s head moves any significant distance in response to the blast or impact.
“This stuff is over before you have any chance to react and probably before you even knew it happened to you,” Paul says. As teenagers, humans’ fastest reaction times are 75-100 milliseconds.
Ford says levels of energy transmitted into the brain by a blast wave “could be part of the injury mechanism associated with TBI and the mechanism by which it happens may not be mitigated by traditional methods of protecting the head with a helmet.”
At Sandia, the researchers created a computer model of a man’s head and neck. The model includes the jaw — another first in TBI research — because a lot of blasts come from improvised explosive devices (IEDs) at ground level, sending waves traveling at the speed of sound through the jaw and facial structure before they reach the brain, Paul says.
Visible Human Project data used
Sandia’s team used the National Library of Medicine’s Visible Human Project — established in 1989 to create a digital image library of volumetric data representing complete, normal adult male and female anatomy — as a guide to build the head and neck model.
Using images of the male, whose age was close to that of most military personnel, Paul, with Ford as a medical consultant, created geometric models of the seven tissue types in the human head — scalp, bone, white and gray brain matter, membranes, cerebral spinal fluid, and air spaces. Over a year, they catalogued each of the tissue types seen in about 300 “slices” of a cadaver’s head, dividing what they saw into one-millimeter cubes and assigning each a tissue type for the computer simulation.
Paul also imported digitally processed, computed tomography (CT) scans of various helmet designs into the simulations to assess the protective merits of each against blast loading.
In a typical blast simulation, 96 processors on Sandia’s Red Sky supercomputer take about a day to process a millisecond of simulated time, Paul says. Since each blast scenario is simulated out to at least 5 milliseconds, each event can take about a week to calculate.
The 3-D simulations are visualized using two-dimensional multicolored images of a man’s head that record an enormous amount of data. Paul and Ford have focused three types of energy entering the brain that may cause TBI: compressive isotropic energy associated with crushing; tensile isotropic energy that tends to expand parts of the brain and could lead to cavitation; and shear energy that causes distortion and tearing of soft tissue. The pressure and stress within the brain show up on videos created from simulation colors moving in slow motion through and around the brain cavity.
On the clinical side, Ford studied 13 subjects who suffered mild TBI after IEDs exploded near them. Some were stunned, most lost consciousness at least briefly, and most cannot hold a job, he says.
The research partners hope to recruit more patients, especially active military personnel or veterans, who were exposed to blasts that did not penetrate the skin and who suffered a loss of consciousness, Ford says. Candidates must have no history of other blunt traumas.
A battery of tests measured the subjects’ memory, language, and intelligence. These results were correlated with changes in functional magnetic resonance imaging (fMRI) from the patients. The 3-D fMRI studies can detect and map networks in the brain used for processes like movement, vision, and attention. By comparing this data with those of a control group, Ford identified a subgroup of networks displaying abnormal brain activity in the patients. These results were then compared with energy deposition maps predicted by the computer simulations.
The research showed that certain regions of patients’ brains are hyperactive, perhaps because they are compensating for adjacent, damaged areas of the brain that were hit with high energy from the blasts. The hyperactive regions were those predicted to experience the least shear and tensile energies, according to the computer simulations, which can be used to predict where the hyperactivity will likely occur, they say.
Validating simulation with clinical reality
The studies also showed problems with how the patients used visual information, which corresponded to their complaints about having difficulty with attention spans, Ford says.
“This is our way to validate what the simulation shows with the clinical reality,” he says.
Once Paul and Ford determine exactly how and where the wave energy deposited in the brain gives rise to injuries, they can identify threshold levels of stress and energy that cause TBI for consideration by helmet designers, Paul says.
Eventually, Paul says these thresholds could be used for sports helmets and even to place sensors on helmets that would show whether a blast was strong enough to have caused TBI. Currently, many TBI sufferers experience no immediate symptoms that would tell them there’s a problem and cause them to seek medical attention. The sensors could be used to alert them to the problem.
“I want us to be able to understand the physical mechanisms that lead to TBI. It would also be useful if we could make the connection between blast loading and blunt impact trauma,” Paul says. “Once we understand that, we can be more comprehensive in how we protect both our warfighters and athletes against these sorts of injuries.”-- Heather Clark
Seismic tools aid in tunnel detection
You’d think it would be easy to use seismic waves to find tunnels dug by smugglers of drugs, weapons, or people.
You’d be wrong.
Sandian Nedra Bonal (6913), who has spent much of her career studying shallow geophysics, is nearing the end of a two-year Early Career Laboratory Directed Research and Development project, “Improving Shallow Tunnel Detection From Surface Seismic Methods,” aimed at understanding the environment around tunnels and why seismic data finds tunnels in some cases but not others.
Her eventual goal is to come up with a seismic detection process for the border and other areas where tunnels pose a security threat.
When tunnels are found today, they’re found by tips from people rather than by scientific methods, she says.
“It would be great if we could use this to do a better job with tunnel detection, that you could scan an area and know if there is or is not a tunnel and find it and stop it,” she says.
If researchers discover the parameters to pinpoint tunnels, the next step would be to develop streamlined seismic methods that would be more practical for the Border Patrol and military.
‘I thought we should see these things’
The LDRD arose from earlier work at Sandia detecting tunnels at fairly shallow depths — 10 to 12 meters, roughly 32 to 39 feet. Nedra says she was surprised when standard refraction and reflection processing techniques used in that work could not successfully pinpoint some tunnels.
“I thought we should see these things and we really weren’t,” she says.
Researchers speculate the difficulty might be due to what’s called a halo effect around a tunnel, in which fracturing and other geological considerations create diffuse boundaries and hide the tunnel, she says. The earlier, broader research produced several successes in tunnel detection, but was not focused specifically on what happens in the area where tunnel and earth meet, which might help explain why tunnels can be detected in some cases but not others.
Nedra is looking at whether seismic waves are strongly impacted by fracturing or saturation of pores in rock or soil, as well as varying pressures at different depths. Physical processes change from shallow depths to deeper depths, but it isn’t clear just where that change occurs, she says.
In addition, the halo effect is both asymmetrical and complex.
“It depends on the geology or the soil as well as the seasonal variation, rain events, and the relation to the water table,” she says. “So it’s a pretty complex regime just from the hydrology standpoint.”
Anomalous areas may be key
Studies still have to be done, but asymmetry may turn out to be an advantage because an asymmetric area might appear to be more uncharacteristic than a symmetrical one, Nedra says. “These anomalous areas are what we may identify as tunnels in the data,” she says.
She began the LDRD project by figuring out what gaps existed in current scientific knowledge, then modeling real-world scenarios based on collected data that would affect hydrology models and in turn, seismic waves — an area’s soil and other geology, how deep fracturing goes into the rock around a tunnel in a particular environment, the probable tunnel size, its relation to the water table, and seasonal variations in that relationship.
“We try to get some bounds to this problem,” Nedra says. “If we can’t see it in the best-case scenario, then there’s really no point in trying to see it in more subtle factors that may affect the seismic waves.”
The team ran the hydrology models to get some results, then converted those results into seismic velocities that could be plugged into Sandia’s 3-D elastic seismic wave propagation simulation code, Nedra says. These results will produce synthetic seismograms that will be compared to field data collected in the real environment and can be used to develop other processing techniques. That will in turn produce data that’s expected to look like data collected in a real environment in the field. “We can then compare the effects of a tunnel versus no tunnel and changes in fracturing and saturation of the tunnel halo versus no changes to assess their impact on seismic waves,” she says.
‘A middle regime where I’m looking . . .’
The standard used to show the relationship of saturation in pores in rock or earth to seismic velocities is an oil industry standard called the Biot-Gassmann theory. Nedra says, however, few experiments have tested that theory at shallow depths where border tunnels are commonly dug.
“The few that have been done have shown that the Biot-Gassmann theory tends to overestimate the velocities for those unconsolidated near-surface materials where the pressures perhaps aren’t as great” as at depths where the oil industry operates, Nedra says.
The very near surface behaves one way, but at some point behaviors change because of greater pressures and other factors, she says. The Biot-Gassmann theory holds well at greater depths where pressure is more intense and the rock is more consolidated, while another theory, Brutsaert, describes what happens very close to the surface.
“But there’s sort of a middle regime where I’m looking where I’m not real sure either one of them works as well as they need to,” Nedra says. She expects to have results soon to compare with prior seismic data to address the issue.
Experimentally verifying at what depth or in what materials competing theories work best lies outside the scope of her LDRD, but she hopes for funding to work on those puzzles. “I think there are still plenty of questions we have that need to be answered but I am very excited about the progress made so far. I have been able to detect a tunnel that I previously had not seen by other analyses,” Nedra says.-- Sue Major Holmes
From Tinian to Albuquerque: Sandia legend Leon Smith passes away at age 92
At the beginning of his engineering career, Leon Smith was part of the group that carried out the atomic attacks on Japan. In that role, he was totally focused on helping win World War II. And then, for the next half-century, Leon was equally focused on ensuring that the nation’s strategic deterrent helped prevent World War III. In the way he did his work and conducted his life, Leon embodied the very best of Sandia, the best of engineering as a profession, the best of America.
Sandia legend Leon Smith died on Sunday, Oct.14, at age 92. He served the Labs for 41 years, rising into management early and overseeing several critical technologies and decisions in Sandia’s evolution. Technically insightful, Leon was also an effective manager who deliberately emulated Sandia Corp. President Jim McRae in being willing to step in and help people but always turning the problem back to them to solve.
At his memorial service on Oct. 18, more than 200 people came together to share their loss and their “Leon stories.” Themes of patriotism, service, family, and the highest of standards wove through the speakers’ remarks. The breadth of his expertise, his excellence, and his warmth were striking. Sandia
President and Labs Director Paul Hommert spoke at the memorial, emphasizing Leon’s impact on Sandia’s systems engineering. In recognition of Leon’s extensive contributions to the Weapon Intern Program, Paul also announced that Sandia will name a classroom after him.
Joining the Manhattan Engineer District
Leon was pursuing a degree in electrical engineering at the University of Wisconsin when he was drafted into the US Army in 1943. He was a private in the field artillery until extensive hearing damage caused him to apply for a transfer to the Army Air Forces. He received training in communications at Yale and was commissioned a second lieutenant, then went on to study electronics at Harvard and radar at MIT. Those experiences landed him a special assignment to the Manhattan Engineer District; he was sent to Wendover, Utah, in November 1944 to join the 509th Composite Group and help set up an electrical lab to develop, assemble, and test fuzing systems for the atomic bomb project.
In the summer of 1945, the 509th relocated to the island of Tinian in the far Pacific to continue training and to prepare for the use of Little Boy and Fat Man against Japanese targets. In addition to preparing the weapons for use, a weaponeer was required to go on the flights to connect the bomb to the aircraft wiring system and move it from safe to armed. A coin toss determined that Morris Jeppson would travel on the Enola Gay to Hiroshima; Leon stayed on Iwo Jima with a backup aircraft. Phil Barnes served as weaponeer on Bockscar, which delivered Fat Man over Nagasaki.
After the war’s end, the Los Alamos laboratory wanted Leon’s service as a weaponeer for the Able airdrop shot of Operation Crossroads, the first postwar nuclear tests. Crossroads was a weapon effects test series for the DoD, and Leon needed to leave the Army to participate. Getting a discharge from the military was a slow process at that point, but, as Leon related, General H. H. “Hap” Arnold made a call to Lowry Air Force Base and Leon was “mustered out in record time — about half an hour.”
After the Crossroads series in the summer of 1946, Leon went to Los Alamos, where his wife, Marie, was working. They returned to Wisconsin and Leon completed his degree. He joined Eastman Kodak in Rochester, N.Y., living in a rented room while Marie, pregnant with their first child, remained in Wisconsin. He was thus tempted when Los Alamos’s Z Division offered him a higher salary and an available two-bedroom house on Sandia Base in Albuquerque. He joined Sandia on Oct. 8, 1947, assigned to work on firing sets in preparation for the Operation Sandstone nuclear tests the following spring.
By 1951, Leon’s leadership skills were as apparent as his technical savvy, and he was promoted to supervisor of an electrical engineering division. Several electrical systems supervisors formed the Electrical Systems Coordination Group to try to achieve more efficient and consistent designs by sharing information from the systems designed for different weapons. This culminated in Leon’s proposal that the organizational structure for electrical systems be changed, with all coordinated out of one department. In 1956, he was promoted to manager of the electrical systems engineering department, which pulled together arming, firing, fuzing, and, later, command and control.
Led many key Sandia initiatives
Leon retained this strong leadership role throughout his career. In 1961, he was promoted to director of electromechanical component development, which proved thrilling as Sandia pushed to develop permissive action links and intersected with the Kennedy administration’s interest in command and control capabilities. Two years later he transferred to systems development, where he was instrumental in creating an extensive advanced development program in weapon systems, which he then led. Soon, there were 10 advanced systems activities underway, including hardened reentry vehicles, advanced measures for safety and control, and the work leading up to the fuze and warhead for the Poseidon.
Leon led six other directorates before retiring. Along the way, he oversaw the doubling of the satellite program’s size. In his final move before retirement, he took over the monitoring systems directorate. He found the effort to develop techniques to support nuclear treaty monitoring exciting, “because it’s at the edge of advanced electronic technology.”
Leon retired June 30, 1988, but returned a decade later when invited to participate in the Weapon Intern Program established by John Hogan with co-instructor Andy Rogulich (both now retired). On Tinian, Leon had taken advantage of down-time to take pictures and had long since assembled about 70 photographs into a presentation on his wartime experiences. His presentations were always successful and had a wide, welcoming audience both within and outside Sandia. [Readers with access to Sandia’s internal website can type “leon smith tinian” into the searchbox on TechWeb; the first search result links to a version of this presentation.]
Andy, who spoke at Leon’s memorial service, remembers, “Leon was always impressed by how many people wanted to hear his stories about the Manhattan Project. Everyone who had the opportunity to hear him speak commented on how much they benefitted from hearing his message, and how Leon made them understand how important their contribution was to the nuclear weapons mission of the United States.”
According to an obituary published in the Albuquerque Journal, Leon “had a passion for fine food and wine and enjoyed sharing it with his family and his many friends.” He is survived by Marie, his wife of 71 years, and by several children, grandchildren, and great-grandchildren.
Leon, a dedicated patriot throughout his long, eventful, and consequential life, was laid to rest in Santa Fe National Cemetery.-- Rebecca Ullrich