This study developed and validated finite element (FE) models of swine and human thoraxes and abdomens that had subject-specific anatomies and could accurately and efficiently predict body responses to blunt impacts. Anatomies of the rib cage, torso walls, thoracic, and abdominal organs were reconstructed from X-ray computed tomography (CT) images and extracted into geometries to build FE meshes. The rib cage was modeled as an inhomogeneous beam structure with geometry and bone material parameters determined directly from CT images. Meshes of soft components were generated by mapping structured mesh templates representative of organ topologies onto the geometries. The swine models were developed from and validated by 30 animal tests in which blunt insults were applied to swine subjects and CT images, chest wall motions, lung pressures, and pathological data were acquired. A comparison of the FE calculations of animal responses and experimental measurements showed a good agreement. The errors in calculated response time traces were within 10% for most tests. Calculated peak responses showed strong correlations with the experimental values. The stress concentration inside the ribs, lungs, and livers produced by FE simulations also compared favorably to the injury locations. A human FE model was developed from CT images from the Visible Human project and was scaled to simulate historical frontal and side post mortem human subject (PMHS) impact tests. The calculated chest deformation also showed a good agreement with the measurements. The models developed in this study can be of great value for studying blunt thoracic and abdominal trauma and for designing injury prevention techniques, equipments, and devices.

Genome-wide association studies have identified polymorphisms at chromosome 9q22.23 as a new thyroid cancer (TC) susceptibility locus in populations of European descent. Since then, the relationship between three common variations (rs965513, rs1867277, and rs71369530) of FOXE1 and TC has been reported in various ethnic groups; however, the results have been inconclusive. To derive a more precise estimation of the relationship as well as to quantify the between-study heterogeneity and potential bias, a meta-analysis including 120,258 individuals from 16 studies was performed. An overall random-effect per-allele odds ratio (OR) of 1.74 (95 % confidence interval (95 % CI), 1.62-1.86, P<10(-5)) and 1.62 (95 % CI, 1.50-1.76, P<10(-5)) was found for the rs965513 and rs1867277 polymorphisms, respectively. In addition, we also detected significant association of FOXE1 polyalanine tract (rs71369530) with TC risk (OR=2.01; 95 % CI, 1.66-2.44, P<10(-5)). Significant associations were also detected under dominant and recessive genetic models. In the subgroup analysis by ethnicity, significantly increased risks were found for the rs965513 polymorphism among Caucasians (OR=1.79; 95 % CI, 1.69-1.91, P<10(-5)) and Asians (OR=1.42; 95 % CI, 1.12-1.81, P=0.004). Ethnicity was identified as a potential source of between-study heterogeneity for rs965513. When stratified by sample size, study design, histological types of TC, and radiation exposure status, significantly increased risks were found for the rs965513 polymorphism. This meta-analysis demonstrated that the three common variations on FOXE1 is a risk factor associated with increased TC susceptibility, but these associations vary in different ethnic populations.

Due to the frequent occurrence of skull fractures from unintended head impacts from kinetic energy weapons, there is an immediate need to develop injury assessment tools for evaluating the risk of skull fracture under the high speed projectile impacts. Skull fracture tolerance has been shown to be dependent on impactor characteristics such as size and shape, as well as subject-specific anatomy. Accurate strain data collected at the fracture location has historically been difficult to measure, which has led to the use of finite element models. Prior research however has used generic finite element (FE) models of the head to determine skull strain and establish FE-based fracture criteria and thus may not be reflective of actual strain in the experimental tests, leading to inaccurate criteria. Additionally, prior FE models have not demonstrated the ability to accurately model fracture patterns. This study reports on two blunt ballistic temporo-parietal head impacts carried out to a post-mortem human subject (PMHS) and the development and validation of a subject-specific FE model. A nine-accelerometer array was mounted to the frontal bone to measure linear and rotational head accelerations. Three rectangular Rosette-style strain gauges were utilized to collect bone strain data surrounding the impact sites. A rigid, flat-faced 38.1 mm diameter projectile with a mass of 0.1 kg was used for all impacts. An accelerometer was mounted to the rear aspect of the projectile for measurement of impactor acceleration and from which impact force was calculated using the projectile mass and applying Newton’s Second Law. A subject-specific finite element head model was developed from the PMHS CT images. Results demonstrated good correlation between experimentally collected strain and accelerometer data to the FE model. The fracture patterns predicted from the model also demonstrated good agreement to fractures observed in the PMHS.

This study used a combined experimental and modeling approach to characterize and quantify the interaction among bullet, body armor, and human surrogate targets during the 10-1000 μs range that is crucial to evaluating the protective effectiveness of body armor against blunt injuries. Ballistic tests incorporating high-speed flash X-ray measurements were performed to acquire the deformations of bullets and body armor samples placed against ballistic clay and gelatin targets with images taken between 10 μs and 1 ms of the initial impact. Finite element models (FEMs) of bullet, armor, and gelatin and clay targets were developed with material parameters selected to best fit model calculations to the test measurements. FEMs of bullet and armor interactions were then assembled with a FEM of a human torso and FEMs of clay and gelatin blocks in the shape of a human torso to examine the effects of target material and geometry on the interaction. Test and simulation results revealed three distinct loading phases during the interaction. In the first phase, the bullet was significantly slowed in about 60 μs as it transferred a major portion of its energy into the body armor. In the second phase, fibers inside the armor were pulled toward the point of impact and kept on absorbing energy until about 100 μs after the initial impact when energy absorption reached its peak. In the third phase, the deformation on the armor's back face continued to grow and energies inside both armor and targets redistributed through wave propagation. The results indicated that armor deformation and energy absorption in the second and third phases were significantly affected by the material properties (density and stiffness) and geometrical characteristics (curvature and gap at the armor-target interface) of the targets. Valid surrogate targets for testing the ballistic resistance of the armor need to account for these factors and produce the same armor deformation and energy absorption as on a human torso until at least about 100 μs (maximum armor energy absorption) or more preferably 300 μs (maximum armor deformation).