Head Restraint Research Articles

Occupant responses in conventional and ABTS seats in high-speed rear sled tests

ABSTRACTObjective: This study compared biomechanical responses of a normally seated Hybrid III dummy on conventional and all belts to seat (ABTS) seats in 40.2 km/h (25 mph) rear sled tests. It determined the difference in performance with modern (≥2000 MY) seats compared to older (<2000 MY) seats and ABTS seats.Methods: The seats were fixed in a sled buck subjected to a 40.2 km/h (25 mph) rear sled test. The pulse was a 15 g double-peak acceleration with 150 ms duration. The 50th percentile Hybrid III was lap–shoulder belted in the FMVSS 208 design position. The testing included 11 <2000 MY, 8 ≥2000 MY, and 7 ABTS seats. The dummy was fully instrumented, including head accelerations, upper and lower neck 6-axis load cells, chest acceleration, thoracic and lumbar spine load cells, and pelvis accelerations. The peak responses were normalized by injury assessment reference values (IARVs) to assess injury risks. Statistical analysis was conducted using Student's t test. High-speed video documented occupant kinematics.Results: Biomechanical responses were lower with modern (≥2000 MY) seats than older (<2000 MY) designs. The lower neck extension moment was 32.5 ± 9.7% of IARV in modern seats compared to 62.8 ± 31.6% in older seats (P =.01). Overall, there was a 34% reduction in the comparable biomechanical responses with modern seats. Biomechanical responses were lower with modern seats than ABTS seats. The lower neck extension moment was 41.4 ± 7.8% with all MY ABTS seats compared to 32.5 ± 9.7% in modern seats (P =.07). Overall, the ABTS seats had 13% higher biomechanical responses than the modern seats.Conclusions: Modern (≥2000 MY) design seats have lower biomechanical responses in 40.2 km/h rear sled tests than older (<2000 MY) designs and ABTS designs. The improved performance is consistent with an increase in seat strength combined with improved occupant kinematics through pocketing of the occupant into the seatback, higher and more forward head restraint, and other design changes. The methods and data presented here provide a basis for standardized testing of seats. However, a complete understanding of seat safety requires consideration of out-of-position (OOP) occupants in high-speed impacts and consideration of the much more common, low-speed rear impacts.

Learning and Stress Shape the Reward Response Patterns of Serotonin Neurons.

The ability to predict reward promotes animal survival. Both dopamine neurons in the ventral tegmental area and serotonin neurons in the dorsal raphe nucleus (DRN) participate in reward processing. Although the learning effects on dopamine neurons have been extensively characterized, it remains largely unknown how the response of serotonin neurons evolves during learning. Moreover, although stress is known to strongly influence reward-related behavior, we know very little about how stress modulates neuronal reward responses. By monitoring Ca2+ signals during the entire process of Pavlovian conditioning, we here show that learning differentially shapes the response patterns of serotonin neurons and dopamine neurons in mice of either sex. Serotonin neurons gradually develop a slow ramp-up response to the reward-predicting cue, and ultimately remain responsive to the reward, whereas dopamine neurons increase their response to the cue but reduce their response to the reward. For both neuron types, the responses to the cue and the reward depend on reward value, are reversible when the reward is omitted, and are rapidly reinstated by restoring the reward. We also found that stressors including head restraint and fearful context substantially reduce the response strength of both neuron types, to both the cue and the reward. These results reveal the dynamic nature of the reward responses, support the hypothesis that DRN serotonin neurons signal the current likelihood of receiving a net benefit, and suggest that the inhibitory effect of stress on the reward responses of serotonin neurons and dopamine neurons may contribute to stress-induced anhedonia.SIGNIFICANCE STATEMENT Both serotonin neurons in the dorsal raphe and dopamine neurons in the ventral tegmental area are intimately involved in reward processing. Using long-term fiber photometry of Ca2+ signals from freely behaving mice, we here show that learning produces a ramp-up activation pattern in serotonin neurons that differs from that in dopamine neurons, indicating complementary roles for these two neuron types in reward processing. Moreover, stress treatment substantially reduces the reward responses of both serotonin neurons and dopamine neurons, suggesting a possible physiological basis for stress-induced anhedonia.

Assessment of mine action shock absorption chair of the crew member of fighting vehicle on compliance to ergonomic requirements

Effectiveness of protection of crew members of armoured equipment against blasting of antivehicle mine depends not only from antistriking characteristics of the chair, but also from its ergonomic characteristics and from the ability of crew members to use protection means properly. The ergonomic characteristics of mine action shock absorption chair were examined analytically – the chair characteristics were compared with the demands of normative documents and by experimental way – in experiments with subjects. Geometrical characteristics of the developed mine action shock absorption chair for protection of crew members of armoured equipment against blasting of antitransport mine generally conforms to requirements of GOST 2188976 «The person operator’s chair. General ergonomic requirements». Differences from requirements of GOST do not conduct to decrease in its ergonomic characteristics. The design of chair fastened system allows to adjust independently belts of fastened system and quickly be recorded in a chair. In the study with participation of 15 subjects it is established that 30minute stay in a chair in summer and winter equipment does not conduct to serious violations of convenience and does not cause noticeable decrease in health, activity and mood of subjects. Placement in winter equipment is a little more comfortable, than in summer equipment. The greatest inconvenience noted by the subjects is connected with the head restraint design, in insufficient degree providing the head support. So, in spite of several small shortcomings, the model of mine action shock absorption chair showed the acceptable level of ergonomic characteristics and in allows to recommend it for conducting further dynamic tests.

Effect of seat belt and head restraint on occupant’s response during rear-end collision

Current neck injury criteria used to evaluate whiplash injuries are based on the kinematics or kinetics of the occupant’s head and neck during rear impacts. The occupant’s response is affected by many factors including impact severity, seat design and occupant related factors such as gender and posture. Most of the current finite element models are concerned with modeling the head and neck, ignoring the interaction of the seat with the occupant during rear collision. In this work the Global Human Body Model Consortium (GHBMC) finite element model was used to study these interaction effects with emphases on the effect of seat belt, headrest and seat stiffness on the occupant’s response during rear-end collisions and evaluate the response using three neck injury criteria. The study shows the dramatic importance of the occupant’s seat restraint and head rest upon occupant safety. Specifically, the occupant ramping during rear impacts can be prevented by using the seat belt. Furthermore, the headrest reduces the head displacement and rotation. Our work further reveals that the head displacement reduction can lead to higher moments, axial and shear forces at the neck, especially for cases involving poorly adjusted or stiffer headrest.

Repetition of Examination Due to Motion Artifacts in Horizontal Cone Beam CT: Comparison among Three Different Kinds of Head Support.

Aims and Objectives:The aim of this study was to evaluate the repetition rate of examination due to motion artifacts in horizontal cone beam computed tomography, using three different kinds of head support, with reference to the patient's age. Further purpose was to evaluate how comfortable head supports were.Materials and Methods:Seven hundred and fifty patients underwent a maxillofacial/dental arches volumetric imaging scan. They were divided into three groups depending on the head support used: foam headrest, foam headrest with head strap, and head restraint helmet. Each group was subdivided into three age groups: ≤18-year-old, 19–65-year-old, and ≥66-year-old patients. A severity index of motion artifacts, divided into four tiers from absence to remarkable artifacts, was adopted. Finally, each patient gave their judgment about the head support comfort by a questionnaire including ten yes/no questions. A three-score scale (insufficient, sufficient, and good) was used to judge the comfort. Collected data were analyzed using the SPSS® version 23.0 statistical analysis software.Results:Forty-one patients (5.4%) repeated the examination. In 16 (2.1%), 15 (2.0%), and 10 (1.3%) of them, foam headrest, foam headrest with head strap, and head restraint helmet were used, respectively. Examination was repeated in 5.3%, 3.8%, and 10.6% in ≤18-year-old, 19–65-year-old, and ≥66-year-old patients, respectively. Patients almost always judged good the comfort for each kind of support. The lowest percentage of satisfaction was observed for the headrest with head strap and was judged good in 78% of the cases.Conclusions:The repetition rate of examination showed similar values among the foam headrest, foam headrest with head strap, and head restraint helmet in under 66-year-old patients. In over 65-year-old patients, the head restraint helmet obviously decreased the repetition rate of examination. All three head supports were good comfort, especially the foam headrest.

Consideration of Neck Injury Protection Performance Criterion for Head Restraint Evaluation Testing

Consideration of Neck Injury Protection Performance Criterion for Head Restraint Evaluation Testing

Prospective motion correction in diffusion-weighted imaging using intermediate pseudo-trace-weighted images

Subject head motion is a major challenge in diffusion-weighted imaging, which requires a precise alignment of images from different time points to allow a reliable quantification of diffusion parameters within each voxel. The technique requires long measurement times, making it highly sensitive to long-term subject motion, even when head restraint is used. Current methods of data analysis rely on retrospective motion correction, but there are potential benefits to using prospective motion correction, in which motion is tracked and compensated for during data acquisition. This technique is regularly used to enhance image quality in blood-oxygen-level dependent (BOLD) imaging, but its application to diffusion-weighted imaging has been limited by the contrast variation between images acquired with different diffusion-gradient directions. This paper describes a novel approach to this topic that exploits the rotational invariance of the trace of the diffusion tensor to reduce the effect of this contrast variation, making it possible to perform a fast image registration using a least-squares cost function. This results in an image-based motion detection algorithm that can be applied in real time during data acquisition to adapt the slice position and orientation in response to subject motion. The motion detection capabilities of the technique were evaluated in a study of ten subjects with b-values up to 3000s/mm². The resulting motion-parameter estimates were in close agreement with reference values provided by interleaved low-b-value images with a correlation coefficient of R=0.9634 for the voxel displacements measured across all subjects and b-values. The technique was also used to perform prospective motion correction on a standard clinical MRI system with b-values up to 2000s/mm². The correction was evaluated in 3 subjects using interleaved low-b-value images, retrospective image registration using the AFNI processing package and mean diffusivity histogram analysis. Compared to acquisitions without motion correction, prospective motion correction based on pseudo-trace-weighted images was found to provide a robust method for substantially reducing the level of misregistration between volumes. In most cases, misregistrations were reduced to less than 0.2mm of translation and 0.2° of rotation for an isotropic voxel size of 2mm, yielding high-quality diffusion parameter maps even in the absence of head restraint and post-acquisition image registration.

Real-world adjustments of driver seat and head restraint in Saab 9-3 vehicles

ABSTRACTObjective: Whiplash-associated disorder (WAD), commonly denoted whiplash injury, is a worldwide problem. These injuries occur at relatively low changes of velocity (typically <25 km/h) in impacts from all directions. Rear impacts, however, are the most common in the injury statistics. Females have a 1.5–3 times higher risk of whiplash injury than males. Improved seat design is the prevailing means of increasing the protection of whiplash injury for occupants in rear impacts. Since 1997, more advanced whiplash protection systems have been introduced on the market, the Saab Active Head Restraint (SAHR) being one of the most prominent. The SAHR—which is height adjustable—is mounted to a pressure plate in the seatback by means of a spring-resisted link mechanism. Nevertheless, studies have shown that seats equipped with reactive head restraints (such as the SAHR) have a very high injury-reducing effect for males (∼60–70%) but very low or no reduction effect for females. One influencing factor could be the position of the head restraint relative to the head, because a number of studies have reported that adjustable head restraints often are incorrectly positioned by drivers. The aim was to investigate how female and male Saab drivers adjust the seat in the car they drive the most.Methods: The seated positions of drivers in stationary conditions have been investigated in a total of 76 volunteers (34 females, 42 males) who participated in the study. Inclusion criteria incorporated driving a Saab 9–3 on a regularly basis.Results: The majority of the volunteers (89%) adjusted the head restraint to any of the 3 uppermost positions and as many as 59% in the top position. The average vertical distance between the top of the head and the top of the head restraint (offset) increase linearly with increasing statures, from an average of −26 mm (head below the head restraint) for small females to an average of 82 mm (head above the head restraint) for large males. On average, the offset was 23 mm for females, which is within a satisfactory range and in accordance with recommendations; the corresponding value for males was 72 mm. The backset tended to be shorter among female volunteers (on average 27 mm) compared to the male volunteers (on average 44 mm). Moreover, the backset tended to increase with increasing statures.Conclusions: Incorrect adjustment of the head restraint cannot explain the large differences found between the sexes in the effectiveness of the SAHR system.

Whiplash Injury or Concussion? A Possible Biomechanical Explanation for Concussion Symptoms in Some Individuals Following a Rear-End Collision.

Study Design Finite element modeling of experimental data. Background The clinical presentations of whiplash injury and concussion have considerable overlap. Both diagnoses are generally based on presenting signs and symptoms, and a history of neck or head trauma. With incomplete knowledge of the trauma, differentiating between whiplash injury and concussion can be clinically challenging. Objectives To estimate the brain strains that develop during rear-end car crashes, evaluate how these strains vary with different head kinematic parameters, and compare these strains to those generated during potentially concussive football helmet impacts. Methods Head kinematic data were analyzed from 2 prior studies, one that focused on head restraint impacts in rear-end crash tests and another that focused on football helmet impacts. These data were used as inputs to a finite element model of the human brain. Brain strains were calculated and compared to different peak kinematic parameters and between the 2 impact conditions. Results Brain strains correlated best with the head's angular velocity change for both impact conditions. The 4 crashes with head angular velocity changes greater than 30 rad/s (greater than 1719°/s) generated the highest brain stains. One crash, in which the head wrapped onto the top of the head restraint, generated brain strains similar to a 9.3-m/s rear football helmet impact, a level previously associated with concussion. Conclusion This work provides new insight into a potential biomechanical link between whiplash injury and concussion, and advances our understanding of how head restraint interaction during a rear-end crash may cause an injury more typically associated with sports-related head impacts. J Orthop Sports Phys Ther 2016;46(10):874-885. doi:10.2519/jospt.2016.7049.

Mechanisms and Mitigation of Head and Spinal Injuries Due to Motor Vehicle Crashes.

Synopsis Head and spinal injuries commonly occur during motor vehicle crashes (MVCs). The goal of this clinical commentary is to discuss real-life versus simulated MVCs and to present clinical, biomechanical, and epidemiological evidence of MVC-related injury mechanisms. It will also address how this knowledge may guide and inform the design of injury mitigation devices and assist in clinical decision making. Evidence indicates that there exists no universal injury tolerance applicable to the entire population of the occupants of MVCs. Injuries sustained by occupants depend on a number of factors, including occupant characteristics (age, height, weight, sex, bone mineral density, and pre-existing medical and musculoskeletal conditions), pre-MVC factors (awareness of the impending crash, occupant position, usage of and position of the seatbelt and head restraint, and vehicle specifications), and MVC-related factors (crash orientation, vehicle dynamics, type of active or passive safety systems, and occupant kinematic response). Injuries resulting from an MVC occur due to blunt impact and/or inertial loading. An S-shaped curvature of the cervical spine and associated injurious strains have been documented during rear-, frontal-, and side-impact MVCs. Data on the injury mechanism and the quantification of spinal instability guide and inform the emergent and subsequent conservative or surgical care. Such care may require determining optimal patient positioning during transport, which injuries may be treated conservatively, whether reduction should be performed, optimal patient positioning intraoperatively, and whether bracing should be worn prior to and/or following surgery. The continued improvement of traditional injury mitigation systems, such as seats, seatbelts, airbags, and head restraints, together with research of newer collision-avoidance technologies, will lead to safer motor vehicles and ultimately more effective injury management strategies. J Orthop Sports Phys Ther 2016;46(10):826-833. Epub 3 Sep 2016. doi:10.2519/jospt.2016.6716.

Design concepts for an integrated whiplash mitigating head restraint and seat

ABSTRACTThis paper presents design of a concept for an integrated head restraint and car seat system to mitigate whiplash in rear-end vehicle collisions. The main emphasis is on a concept, which combines a reactive head restraint with a reactive seat. The chosen concept is developed in the form of mechanical linkages using linkage analysis software, SAM 6.1. A human model positioned in a ‘good’ driving posture is used to show how the head restraint and seat would operate using a typical crash pulse used for dynamic sled testing of automotive seats. The head restraint system is capable of translating into an optimal position of 40 mm forwards and 60 mm upwards in 12 ms, before whiplash-induced injuries start to take place. The reactive seat is also capable of reclining 15 degrees. The combination of reducing the backset and reclining the seat to reduce the relative motion between the head and torso has the potential to reduce the whiplash-effect-related injuries in rear-end collisions.

Human Trafficking Should Be on Psychiatrists’ Radar

Back to table of contents Previous article Next article Clinical and Research NewsFull AccessHuman Trafficking Should Be on Psychiatrists’ RadarAaron LevinAaron LevinSearch for more papers by this authorPublished Online:12 Jul 2016https://doi.org/10.1176/appi.pn.2016.7a10AbstractSex trafficking entraps young people but inevitable encounters with the medical system can offer a chance for escape.Sex trafficking of children and adolescents may be largely hidden from the eyes of the public, but when these young people seek medical care, it opens the door to intervention—provided the doctor becomes aware of their situation.Psychiatrists should be especially alert to this population, said Rachel Robitz, M.D., a PGY-4 in psychiatry and family medicine at the University of California, San Diego, during a special session sponsored by APA’s Division of Diversity and Health Equity at APA’s Annual Meeting in Atlanta.According to Robitz, only 13 percent of individuals in the United States who are recruited into sex trafficking are over the age of 25, and 83 percent are U.S. citizens. She noted that clinical samples show this population tends to have high levels of depression, anxiety, nightmares, substance abuse, overdoses, and suicide attempts. “We also know that 88 percent of these young people saw a medical provider during the time they were being trafficked,” said pediatrician Jordan Greenbaum, M.D., of Children’s Healthcare of Atlanta.“They are seen in the emergency room or as inpatients for many different reasons, but not for ‘trafficking,’ ” said Mariam Garuba, M.D., an assistant clinical professor of psychiatry at the Columbia University Medical Center. “The question in your mind should be: ‘Is this a survivor?’”If children seem intimidated by the adults who brought them in or can’t say where they came from or give their address, clinicians should have a heightened level of suspicion, said Greenbaum. Other risk factors suggesting that a person might be being exploited for sex include illicit drug use, abuse or neglect, self-harm, or running away from home. Nearly half of those being trafficked have an active case of sexually transmitted infections, and 30 percent have been pregnant.To best respond to the needs of a patient who may be being trafficked, an evaluation should ideally occur with the accompanying adult eased out of the room, she said.“Obtain a history to assess both the health and the safety needs of the child,” said Greenbaum. “Diagnose and treat both acute and chronic conditions, since the latter may be a clue to long-term maltreatment. Document acute or remote head injuries, cigarette burns, or restraint injuries.”Tests for pregnancy and sexually transmitted diseases may be appropriate, too, she said.A trauma-informed approach to treating these patients is essential, she said. Many of these children might seem “belligerent,” but in fact they are traumatized, said Greenbaum. Questions that address trafficking might include the following:“Has anyone ever asked you to have sex in exchange for something you wanted or needed—money, food, or shelter?”“Has anyone ever asked you to have sex with another person?”“Has anyone ever taken sexual pictures of you or posted such pictures on the Internet?”While the role of the clinician is to assess the child’s emotional and physical health and safety, provide information to the child, and offer referral and resources, providers must be aware of mandated reporting laws and should explain those to the victim—early in the conversation—to avoid a sense of betrayal. “Watch for cues of stress to avoid retraumatization,” she said.A program in Boston called “My Life, My Choice” seeks to prevent girls from being trafficked in the first place.“Pimps pick on vulnerable girls in recruitment,” said Emily Rothman, Sc.D., an associate professor at the Boston University School of Public Health. Besides sexually seducing the girls, the pimps introduce them to a life that initially seems filled with money and glamour until they are entrapped.The Boston program arranges group discussions with young women believed to be at risk of being trafficked, who are referred by schools and residential treatment centers. The program teaches about exploitation, unhealthy dating relationships, and the recruitment process in order to increase the girls’ perception of the industry’s dangers, not its purported glamorousness. They also hear firsthand from people who have been exploited.Ultimately, young people who have been trafficked must decide for themselves that they want to get out of their situation, said Garuba. The trafficked life can be understood as a form of addiction, and relapse is likely.“You need to plant the seed,” she said. “Maybe the next therapist will help them take that next step.” ■More information about human trafficking can be accessed here. ISSUES NewArchived

IIHS head restraint ratings and insurance injury claim rates

ABSTRACTObjectives: The Insurance Institute for Highway Safety (IIHS) rates front seat/head restraint designs using a combination of static and dynamic measurements following RCAR-IIWPG procedures. The purpose of this study was to determine whether vehicles with better IIHS-rated seats/head restraints had lower injury risk in rear-end collisions and how the effect of better rated seats interacted with driver gender and age.Methods: The presence of an associated insurance injury claim was determined for rear-impact crashes using 2001–2014 model year cars and SUVs. Logistic regression was used to compare injury risk for vehicles with good, acceptable, and marginal IIHS-rated seats/head restraints with poor-rated seats/head restraints. Analyses were run by gender and driver age and also by the rate of more severe injury claims.Results: Injury rates were 11.2% lower for vehicles with seats/head restraints rated good compared to vehicles with seats/head restraints rated poor. The percentage reduction for good- versus poor-rated seats was greater for females (12.7%) than males (8.9%). Comparing good- with poor-rated seats, driver ages 15–24 had the largest reduction at 19.8%, followed by 10.7% for driver ages 45–64 and 10.4% for driver ages 25–44.Conclusions: Seats/head restraints with better IIHS ratings are associated with lower injury rates in rear-impact collisions than seats rated poor. The reductions in injury rates were strongest for females and for young-to–middle-age drivers. The strong reductions in injury rates for these groups are encouraging given their high initial injury rates.

Методика повышения безопасности автомобилей за счет улучшения параметров кресел с пассивными и активными подголовниками

Методика повышения безопасности автомобилей за счет улучшения параметров кресел с пассивными и активными подголовниками

Improved frame-based estimation of head motion in PET brain imaging.

Head motion during PET brain imaging can cause significant degradation of image quality. Several authors have proposed ways to compensate for PET brain motion to restore image quality and improve quantitation. Head restraints can reduce movement but are unreliable; thus the need for alternative strategies such as data-driven motion estimation or external motion tracking. Herein, the authors present a data-driven motion estimation method using a preprocessing technique that allows the usage of very short duration frames, thus reducing the intraframe motion problem commonly observed in the multiple frame acquisition method. The list mode data for PET acquisition is uniformly divided into 5-s frames and images are reconstructed without attenuation correction. Interframe motion is estimated using a 3D multiresolution registration algorithm and subsequently compensated for. For this study, the authors used 8 PET brain studies that used F-18 FDG as the tracer and contained minor or no initial motion. After reconstruction and prior to motion estimation, known motion was introduced to each frame to simulate head motion during a PET acquisition. To investigate the trade-off in motion estimation and compensation with respect to frames of different length, the authors summed 5-s frames accordingly to produce 10 and 60 s frames. Summed images generated from the motion-compensated reconstructed frames were then compared to the original PET image reconstruction without motion compensation. The authors found that our method is able to compensate for both gradual and step-like motions using frame times as short as 5 s with a spatial accuracy of 0.2 mm on average. Complex volunteer motion involving all six degrees of freedom was estimated with lower accuracy (0.3 mm on average) than the other types investigated. Preprocessing of 5-s images was necessary for successful image registration. Since their method utilizes nonattenuation corrected frames, it is not susceptible to motion introduced between CT and PET acquisitions. The authors have shown that they can estimate motion for frames with time intervals as short as 5 s using nonattenuation corrected reconstructed FDG PET brain images. Intraframe motion in 60-s frames causes degradation of accuracy to about 2 mm based on the motion type.

High-Fidelity Simulation of Primary Blast: Direct Effects on the Head.

The role of primary blast in blast-induced traumatic brain injury (bTBI) is controversial in part due to the technical difficulties of generating free-field blast conditions in the laboratory. The use of traditional shock tubes often results in artifacts, particularly of dynamic pressure, whereas the forces affecting the head are dependent on where the animal is placed relative to the tube, whether the exposure is whole-body or head-only, and on how the head is actually exposed to the insult (restrained or not). An advanced blast simulator (ABS) has been developed that enables high-fidelity simulation of free-field blastwaves, including sharply defined static and dynamic overpressure rise times, underpressures, and secondary shockwaves. Rats were exposed in head-only fashion to single-pulse blastwaves of 15 to 30 psi static overpressure. Head restraints were configured so as to eliminate concussive and minimize whiplash forces exerted on the head, as shown by kinematic analysis. No overt signs of trauma were present in the animals post-exposure. However, significant changes in brain 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) and neurofilament heavy chain levels were evident by 7 days. In contrast to most studies of primary blast-induced TBI (PbTBI), no elevation of glial fibrillary acidic protein (GFAP) levels was noted when head movement was minimized. The ABS described in this article enables the generation of shockwaves highly representative of free-field blast. The use of this technology, in concert with head-only exposure, minimized head movement, and the kinematic analysis of the forces exerted on the head provide convincing evidence that primary blast directly causes changes in brain function and that GFAP may not be an appropriate biomarker of PbTBI.

An energy-absorbing sliding seat for reducing neck injury risks in rear impact—analysis for prototype built

ABSTRACTObjective: This study investigated overall performance of an energy-absorbing sliding seat concept for whiplash neck injury prevention. The sliding seat allows its seat pan to slide backward for some distance under certain restraint force to absorb crash energy in rear impacts.Methods: A numerical model that consisted of vehicle interior, seat, seat belt, and BioRID II dummy was built in MADYMO to evaluate whiplash neck injury in rear impact. A parametric study of the effects of sliding seat parameters, including position and cushion stiffness of head restraint, seatback cushion stiffness, recliner characteristics, and especially sliding energy-absorbing (EA) restraint force, on neck injury criteria was conducted in order to compare the effectiveness of the sliding seat concept with that of other existing anti-whiplash mechanisms. Optimal sliding seat design configurations in rear crashes of different severities were obtained. A sliding seat prototype with bending of a steel strip as an EA mechanism was fabricated and tested in a sled test environment to validate the concept. The performance of the sliding seat under frontal and rollover impacts was checked to make sure the sliding mechanism did not result in any negative effects.Results: The protective effect of the sliding seat with EA restraint force is comparable to that of head restraint–based and recliner stiffness–based anti-whiplash mechanisms. EA restraint force levels of 3 kN in rear impacts of low and medium severities and 6 kN in impacts of high severity were obtained from optimization. In frontal collision and rollover, compared to the nonsliding seat, the sliding seat does not result in any negative effects on occupant protection. The sled test results of the sliding seat prototype have shown the effectiveness of the concept for reducing neck injury risks.Conclusion: As a countermeasure, the sliding seat with appropriate restraint forces can significantly reduce whiplash neck injury risk in rear impacts of low, medium, and high severities with no negative effects on other crash load cases.

Sources of noise during accumulation of evidence in unrestrained and voluntarily head-restrained rats.

Decision-making behavior is often characterized by substantial variability, but its source remains unclear. We developed a visual accumulation of evidence task designed to quantify sources of noise and to be performed during voluntary head restraint, enabling cellular resolution imaging in future studies. Rats accumulated discrete numbers of flashes presented to the left and right visual hemifields and indicated the side that had the greater number of flashes. Using a signal-detection theory-based model, we found that the standard deviation in their internal estimate of flash number scaled linearly with the number of flashes. This indicates a major source of noise that, surprisingly, is not consistent with the widely used 'drift-diffusion modeling' (DDM) approach but is instead closely related to proposed models of numerical cognition and counting. We speculate that this form of noise could be important in accumulation of evidence tasks generally.

Design concepts for an integrated whiplash mitigating head restraint and seat

ABSTRACTThis paper presents design of a concept for an integrated head restraint and car seat system to mitigate whiplash in rear-end vehicle collisions. The main emphasis is on a concept, which combines a reactive head restraint with a reactive seat. The chosen concept is developed in the form of mechanical linkages using linkage analysis software, SAM 6.1. A human model positioned in a ‘good’ driving posture is used to show how the head restraint and seat would operate using a typical crash pulse used for dynamic sled testing of automotive seats. The head restraint system is capable of translating into an optimal position of 40 mm forwards and 60 mm upwards in 12 ms, before whiplash-induced injuries start to take place. The reactive seat is also capable of reclining 15 degrees. The combination of reducing the backset and reclining the seat to reduce the relative motion between the head and torso has the potential to reduce the whiplash-effect-related injuries in rear-end collisions.

Technical Note: Immunohistochemical evaluation of mouse brain irradiation targeting accuracy with 3D-printed immobilization device.

Small animal immobilization devices facilitate positioning of animals for reproducible imaging and accurate focal radiation therapy. In this study, the authors demonstrate the use of three-dimensional (3D) printing technology to fabricate a custom-designed mouse head restraint. The authors evaluate the accuracy of this device for the purpose of mouse brain irradiation. A mouse head holder was designed for a microCT couch using cad software and printed in an acrylic based material. Ten mice received half-brain radiation while positioned in the 3D-printed head holder. Animal placement was achieved using on-board image guidance and computerized asymmetric collimators. To evaluate the precision of beam localization for half-brain irradiation, mice were sacrificed approximately 30 min after treatment and brain sections were stained for γ-H2AX, a marker for DNA breaks. The distance and angle of the γ-H2AX radiation beam border to longitudinal fissure were measured on histological samples. Animals were monitored for any possible trauma from the device. Visualization of the radiation beam on ex vivo brain sections with γ-H2AX immunohistochemical staining showed a sharp radiation field within the tissue. Measurements showed a mean irradiation targeting error of 0.14±0.09 mm (standard deviation). Rotation between the beam axis and mouse head was 1.2°±1.0° (standard deviation). The immobilization device was easily adjusted to accommodate different sizes of mice. No signs of trauma to the mice were observed from the use of tooth block and ear bars. The authors designed and built a novel 3D-printed mouse head holder with many desired features for accurate and reproducible radiation targeting. The 3D printing technology was found to be practical and economical for producing a small animal imaging and radiation restraint device and allows for customization for study specific needs.