Ranking and rating bicycle helmet safety performance in oblique impacts using eight different brain injury models

Bicycle helmets are shown to offer protection against head injuries. Rating methods and test standards are used to evaluate different helmet designs and safety performance. Both strain-based injury criteria obtained from finite element brain injury models and metrics derived from global kinematic responses can be used to evaluate helmet safety performance. Little is known about how different injury models or injury metrics would rank and rate different helmets. The objective of this study was to determine how eight brain models and eight metrics based on global kinematics rank and rate a large number of bicycle helmets (n=17) subjected to oblique impacts. The results showed that the ranking and rating are influenced by the choice of model and metric. Kendall’s tau varied between 0.50 and 0.95 when the ranking was based on maximum principal strain from brain models. One specific helmet was rated as 2-star when using one brain model but as 4-star by another model. This could cause confusion for consumers rather than inform them of the relative safety performance of a helmet. Therefore, we suggest that the biomechanics community should create a norm or recommendation for future ranking and rating methods

Regional mechanical and biochemical properties of the porcine cortical meninges

peer-reviewedThe meninges are pivotal in protecting the brain against traumatic brain injury (TBI), an ongoing issue in most mainstream sports. Improved understanding of TBI biomechanics and pathophysiology is desirable to improve preventative measures, such as protective helmets, and advance our TBI diagnostic/prognostic capabilities. This study mechanically characterised the porcine meninges by performing uniaxial tensile testing on the dura mater (DM) tissue adjacent to the frontal, parietal, temporal, and occipital lobes of the cerebellum and superior sagittal sinus region of the DM. Mechanical characterisation revealed a significantly higher elastic modulus for the superior sagittal sinus region when compared to other regions in the DM. The superior sagittal sinus and parietal regions of the DM also displayed local mechanical anisotropy. Further, fatigue was noted in the DM following ten preconditioning cycles, which could have important implications in the context of repetitive TBI. To further understand differences in regional mechanical properties, regional variations in protein content (collagen I, collagen III, fibronectin and elastin) were examined by immunoblot analysis. The superior sagittal sinus was found to have significantly higher collagen I, elastin, and fibronectin content. The frontal region was also identified to have significantly higher collagen I and fibronectin content while the temporal region had increased elastin and fibronectin content. Regional differences in the mechanical and biochemical properties along with regional tissue thickness differences within the DM reveal that the tissue is a non-homogeneous structure. In particular, the potentially influential role of the superior sagittal sinus in TBI biomechanics warrants further investigation

LGBT in the military : Policy development in Sweden 1944–2014

This article contributes to the growing field of research on military LGBT policy development by exploring the case of Sweden, a non-NATO-member nation regarded as one of the most progressive in terms of the inclusion of LGBT personnel. Drawing on extensive archival work, the article shows that the story of LGBT policy development in the Swedish Armed Forces from 1944 to 2014 is one of long periods of status quo and relative silence, interrupted by leaps of rapid change, occasionally followed by the re-appearance of discriminatory policy. The analysis brings out two periods of significant change, 1971–1979 and 2000–2009, here described as turns in LGBT policy. During the first turn, the military medical regulation protocol’s recommendation to exempt gay men from military service was the key issue. During these years, homosexuality was classified as mental illness, but in the military context it was largely framed in terms of security threats, both on a national level (due to the risk of blackmail) and for the individual homosexual (due to the homophobic military environment). In the second turn, the focus was increasingly shifted from the LGBT individual to the structures, targeting the military organization itself. Furthermore, the analysis shows that there was no ban against LGBT people serving in the Swedish Armed Forces, but that ways of understanding and regulating sexual orientation and gender identity have nonetheless shaped the military organization in fundamental ways, and continue to do so.Funding agencies: Swedish Council for Working Life and Social Research [2012-0934]; Royal Swedish Academy of Sciences [FOA10Amund-007, FOA12Amund-010]</p