A new study of the damage created by large tornadoes has just been published. Dr. Arijit Sinha of Oregon State University says he was prompted to participate because they know there can be improvements in construction practices. He says one of the most common problems is a lack of fasteners within the damaged structures.  He says they discovered it might be time for an upgrade to modern building codes. They're hoping the study will be the beginning of an eventual shift to more engineered construction and better building standards.