we found that the ribs get more horozonta.u can see this as its manifested as a barrel-chested appearance as we get older. and if you look at the way a seat belt might load those two structures, on the case of the left, that seat belt load is going to introduce deformations of the, -- of the spine, which is the kind of loading. on the right, you can imagine deforming that chest like a barrel, so instead of putting stress on the spine, you are putting it on the chest itself. so the chest is at a disadvantage for front-loading. so the biomechanics of aging are important to consider. we did a study where we estimated that the age of america over the last decade generated about half as many serious injuries as increased seat belt use prevented. i think biomechanics is a key solution and incorporating it into things like federal standards and safety measures is important. thank you. >> thank you, dr. kent. >> our third panelist is chief of the human injury research division at the national highway traffic safety administration. pri