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Biomechanics of primary traumatic head injury
Published in Helen Whitwell, Christopher Milroy, Daniel du Plessis, Forensic Neuropathology, 2021
Whilst a is again the peak linear acceleration during impact, the time (t2−t1) is more sensitively considered to include only the injurious time duration, either side of the peak acceleration-time waveform, rather than the total duration. A further series of experimental studies was conducted on adult cadavers, collating skull fracture and brain injury data with corresponding HIC values a specific injury risk curve developed, which was originally intended for use during production vehicle impact safety tests but now is used for other applications, including sports and forensics. During crash testing, regulated vehicle/barrier interactions, a crash test dummy head HIC value of 1000 (associated with a 16–18 per cent risk of severe or fatal head injury) is considered as the pass/fail threshold. HIC safety thresholds for the avoidance of head injury are in the region of 570, 723, 779, 700 and 670 for 3 year olds, 6 year olds, small females, mid-sized males and large males, respectively (Klinich et al. 2002) child dummies, a lower HIC value of 800 is applied and for infant dummies, 377, 390 and 440, corresponding to ages 6, 12 and 18 months, respectively (Mertz et al. 1997). These values have been immensely important in informing forensic investigations.
mTBI in the Military and Contact Sports
Published in Mark A. Mentzer, Mild Traumatic Brain Injury, 2020
This further complicates the design of protective equipment for blast as well as testing to determine injury mechanisms and thresholds. Biofidelic test manikins record only biomechanical parameters with inconclusive links to the injury physiology and to animal models. Head injury criterion (HIC) may be used to predict risk of injury. But they do not account for factors in injury tolerance over time; nor do they account for complex blast parameters such as reflections, reverberation, and interactions of pressure waves within buildings or breached vehicles (Desmoulin and Dionne, 2009). But peak intracranial pressure may represent a reasonable overall predictor of tissue injury (Chen et al., 2009).
Biomechanics of Brain Injury in Athletes
Published in Mark R. Lovell, Ruben J. Echemendia, Jeffrey T. Barth, Michael W. Collins, Traumatic Brain Injury in Sports, 2020
A third approach is to use the average resultant linear acceleration and the time duration of the entire impact event itself. The most widely known relationship employing this approach is that associated with the Wayne State University concussion tolerance curve (Gurdjian et al., 1964). It is of the form a-2.5 T < 1,000 where T is the total time duration of the impact event expressed in seconds.9 It too basically says the lower the acceleration the longer it can be sustained.10 Historically, the equation provides a boundary between a “safe’ and “unsafe” headform response. It has never actually been used in any performance test but is the basis for the Severity Index SI (Gadd, 1966). It is of the form where a is the time dependent resultant linear acceleration of the center of gravity of the head. With acceleration expressed in Gs, the SI is set to a limiting value of 1200 in the current NOCSAE standard for football helmets (NOCSAE, 1997). A more complex but mathematically more appropriate expression of the above is the Head Injury Criterion HIC. It is of the form.
Investigation of traffic accidents involving seated pedestrians using a finite element simulation-based approach
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Daniel Grindle, Ahmed Balubaid, Costin Untaroiu
The goal of this study was to explore seated pedestrian’s mortality in CPCs, so only life-threatening injuries of the head and upper body were examined in this study. Simulation outcomes of interest were head injury criteria (HIC) (Hertz 1993), brain injury criteria (BrIC) (Takhounts et al. 2013), and abdominal and thoracic compression (Viano et al. 1989) (Table 2). HIC was calculated using the nodal acceleration of the head’s center of gravity. BrIC was calculated using the nodal angular velocity of the head’s center of gravity. Abdominal and thoracic compression were calculated using the distances between nodes along the surface of the M50-OS abdomen and thorax. Injury probabilities were calculated based on injury risk curves developed in PMHS studies for +4 Abbreviated Injury Scale (AIS) injuries (life-threatening injuries). All injury outcomes were based on probability curves and were not threshold based. Neck injury was not examined in this study. Standard neck injury criteria measure relies on axial forces and sagittal moments (Eppinger et al. 1999) but the seated pedestrian in this study primarily experienced lateral moments. Relating the coronal plane-based neck injury criteria to the standard sagittal plane-based injury has been shown to report inaccurate injury probabilities (Whyte et al. 2020), thus, neck injury was not examined.
Comparison of the effectiveness of rotating seats in autonomous vehicles and airbags in traditional vehicles to minimize head injuries in frontal crash
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Na Yang, Jiexiong Wang, Tao Liu
The head injury criterion (HIC) is a validated tool for assessing head injury. It was proposed by the NHTSA and was evolved from the Wayne State tolerance curve (WSTC) (Gurdjian et al. 1955); it is expressed as
Introduction to the special issue on gastroenterology
Published in Paediatrics and International Child Health, 2019
H. pylori is associated with chronic active gastritis (usually asymptomatic), peptic ulcer and gastric cancer. In LMIC, it is often acquired in early childhood and the prevalence may be up to 60–80% owing to poor socio-economic status, over-crowding and poor sanitation and hygiene. It is transmitted by faecal/oral, gastric/oral and oral/oral routes. Its prevalence in HIC is 1–12%. The relationship between H. pylori infection and gastro-intestinal symptoms in children is unclear; there is no evidence that it is a cause of recurrent abdominal pain. The ability of H. pylori to cause gastro-intestinal disease relates particularly to virulence factors.