Driver's Seat Research Articles

CENTRAL APNEA SECONDARY TO DISSEMINATED HISTOPLASMOSIS

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Occupational exposures can be an important cause of pathology, especially in the respiratory system. Histoplasmosis is an endemic, yet oft-missed multisystem pathogen, which involves the central nervous system in up to 10% of cases (1). CASE PRESENTATION: A previously healthy man was found unresponsive in the driver's seat of his car in the parking lot at work; he did not arouse to narcan and was intubated. A new lung nodule with a "halo sign" prompted fungal work up, positive for urine and serum antigens consistent with disseminated histoplasmosis. Bronchoalveolar lavage and lumbar puncture fungal studies were negative. MRI had right cerebellar lesion and EEG showed left temporal focal delta waves. When ventilated he was well-appearing and followed commands, but failed initial extubation due to apnea and marked acidosis. He was initiated on amphotericin B and re-extubated, transitioned to 1 year azole. Urine drug screen was positive for methadone, a potential confounder, however the lack of response to narcan and his level of alertness while the ventilator was controlling his acid-base status makes opiates less likely. Later he admitted extensive exposure to bird feces over the month prior to admission; his work as a Heating, Ventilation, and Air Conditioning technician inside an old office building in the Midwestern United States involved "cleaning up dead birds." DISCUSSION: Mr. H's case is an atypical presentation in an atypical patient. While he did have a stereotypical lung nodule, his primary problem was neurologic, respiratory drive rather than the lung parenchyma. He was HIV-negative, not immunosuppressed, with excellent functional status. 5-10% of disseminated histoplasmosis will have CNS infection and up to half of those cases occurred in immunocompetent individuals (1). CNS histoplasmosis has varied symptoms; current review of literature does not yield any mentioning central apnea, however, one case series centered on the well-known outbreak in Indianapolis discussed 18 cases with CNS involvement, of which 4 had the presenting symptom of "coma" (1). Review of other cases (compilation of 104 case reports) showed that with CNS involvement of histoplasmosis, "altered level of consciousness" was present in 50% (1). CONCLUSIONS: Histoplasma capsulatum is an endemic mycose which can impact immunocompetent patients and involve the CNS. It is often taught in medical school that "histo hides" because it is notoriously difficult to detect; it is even harder to find if one is not looking for it, so careful review of imaging and thorough occupational history are critical to including fungal pathogens on the differential. REFERENCE #1: Riddell J 4th, Wheat LJ. Central Nervous System Infection with Histoplasma capsulatum. J Fungi (Basel). 2019 Jul 24;5(3):70. doi: 10.3390/jof5030070. PMID: 31344869; PMCID: PMC6787664. DISCLOSURES: No relevant relationships by Daniel O'Connor, source=Web Response

Experimental Study on Different Types of Curves for Ride Comfort in Automated Vehicles

Vehicle automation is among the best possible solutions for traffic issues, including traffic accidents, traffic jams, and energy consumption. However, the user acceptance of automated vehicles is critical and is affected by riding comfort. In addition, human factors in automated vehicle control should be clear. This study evaluates the effect of different courses on driving comfort in automated vehicles using field experiments with 25 subjects. This study focused on lateral motion, but speed control was not targeted. Further, generating a path for obstacle avoidance and lane keeping, which have several constraining conditions, was also not targeted. Rendering a comfortable path is beneficial for developing an acceptable system as a car developer and for building new curves for automated or driving assistance systems from the perspective of construction. The automated vehicle drove at a speed of 30 km/h on four courses, namely, clothoid, two types of spline curves, and arc, based on the real intersection. Each participant sat on both the driver and passenger seat and answered a questionnaire. The experimental data indicated the clothoid course to be the most comfortable, while the arc was most uncomfortable for a significance level of 1%. These tendencies are applicable to driver and passenger seats, all genders, and experiences and will be beneficial for human factor research in automated vehicle control.

Exposure to Whole-Body Vibration in Commercial Heavy-Truck Driving in On- and Off-Road Conditions: Effect of Seat Choice.

Trucking is a key industry in Canada with around 180 000 professional drivers. As an industry it has a disproportionately high injury claim rate, particularly for back injuries. Whole-body vibration (WBV) can contribute to the onset and development of low back disorders, and is a well-documented exposure among driving professions. A widely adopted WBV mitigation measure focuses on hydraulic and/or pneumatic passive suspension systems both in the driver's seat and underneath the vehicle cab. Passive suspension 'air-ride' seats are the current industry standard but new technologies such as the electromagnetic active vibration cancelling (EAVC) seats offer potentially substantial improvements in WBV reduction. In this paper, we evaluate and compare four commonly used truck seats (three air-ride, one EAVC) for their vibration damping characteristics and WBV exposure attenuation in on- and off-road conditions. We recruited 24 professional truck drivers who drove 280 km (mixed on-road and off-road) in ore-haul trucks under four different seating conditions. Following the ISO 2631-1 WBV standard, vibration measurements were made on the cab floor and seat pad, and 8-h average weighted vibration (A(8)) and 8-h vibration dose values (VDV(8)) were calculated, as well as the Seat Effective Amplitude Transmissibility (SEAT), and daily vibration action limits (DVALs). These measures were compared between seat types, as well as road conditions. The EAVC seat gave best performance for both A(8) (0.27 m s-2) and VDV(8) (6.6 m s-1.75). The EVAC seat had the lowest SEAT tested (36.2%) and the longest DVAL. However, among the three passive air-suspension seats, two showed significantly reduced A(8) (0.43 and 0.44 m s-2) and VDV(8) (9.1 and 9.3 m s-1.75) exposures relative to the third passive air-suspension seats [A(8) (0.54 m s-2) and VDV(8) (11.1 m s-1.75)]. These differences in exposures among the three passive air-suspension seats resulted in varying DVAL times, with the worst performing seat reaching the DVAL after only 6.3 h of driving. There was also a seat by road type interaction; there were performance differences between the passive air-suspension seats on-road, but not off-road. The observed reduction of the WBV exposures measured from the EAVC seat was consistent with previous results. But we showed that there can also be substantive differences among seats that are the current industry standard. These differences were more evident on-road than off-road, which suggests that more work needs to be done to understand seat performance characteristics, and in matching the correct seat technology to the driving task. We demonstrated that WBV exposures in current industry conditions may exceed health-based exposure limits; this has policy relevance because WBV exposures are linked to prevalent and costly adverse health conditions in a working population that is ageing. Increased WBV measurement collection is recommended to ensure the anticipated exposure attenuations are achieved when seats are relied upon as an engineered control against WBV.

Artificial intelligent based smart system for safe mining during foggy weather

AbstractOpencast mining operations at hilly areas are usually affected during foggy weather due to the inability of drivers to operate heavy earth‐moving machinery in low visibility conditions. This article deals with an intelligent vision enhancement system for continuing opencast mining operations during foggy weather. The system integrates hardware and software to provide multistage safety features that make it unique from existing systems. The system includes hardware like thermal cameras, high definition cameras, proximity radar, wireless devices, GNSS module, graphical processing unit, display unit, and so forth, and image processing software, namely real‐time image stitching, image enhancement, and object detection using convolutional neural networks. The integrated system and algorithms display a 180° panorama field view of the vehicle's front using real‐time video stitching. The front view after image processing, rear camera view, object detection through proximity radar, and real‐time location of the vehicles on a 3D geo‐tagged mine map by GNSS modules are displayed in four splitter windows on a touch screen fitted on the dashboard in front of the driver's seat. The driver can drive the vehicle by seeing the display screen during foggy weather. The output image of the developed image‐processing algorithm has less distortion, better quality, and better depth perception than existing methods. Overall, there are significant improvements in the persistence of the color elements by 39.65%, contrast by 4.62%, and the corresponding entropy by 7.11% concerning the similar existing methods. The final system has been successfully tested in an opencast mine.

Smart Security System for Theft Protection Using Face Recognition

The number of car robbery attempts at the local and international scale is rising rapidly in this modern era. By inventing robbery techniques, the owners are afraid that their cars will be robbed from their ordinary parking lot or from outside. This makes vehicle protection against robbery important as a result of insecurity. The computer vision based real-time vehicle safety system solves this problem. The proposed car safety system carries through real time user authentication based on image processing using face detection and recognition techniques and a microprocessor-based control system attached to the car. The infrarot sensor attached to the driver's vehicles seat activates the hidden camera, which is fixed inside the vehicle, as the person enters the parked vehicle overcoming the existing security features. The person's face is detected using Viola Jones algorithm once the image is obtained from the activated camera. The extracted face is recognized using the improved Linéar Discriminant Analysis (LDA) algorithm that distinguishes many features rather than looking for an exact pattern based on the Euclidean distance. Authorization requires that the threshold value is established and compared to the Euclidean distance over which the person is not authenticated. The face is sent to the mobile of the owner as an MMS via the operating GSM modem, which is classified as unknown. The owner shall be controlled with the relay in accordance with the owner’s command when the information is received. The way to authenticate the person would be efficient and efficient in terms of vehicle safety.

Effects of a Bolster Curvature on an Automobile Seat Fit

Vehicle-seat dimensions measured at specific cross-sections have been historically utilized as shape determinants to evaluate a driver’s seat fit. The present study is intended to quantify the relationships between seat fits and the seat dimensions for designing an ergonomic vehicle seat. Eight seat engineers evaluated seat fits for 54 different driver seats based on their expertise. Five seat dimensions were measured at six cross-sectional planes using a custom-built, computerized program. The best-subset-logistic-regression method was employed to model the relationships between the seat fit and the seat dimensions. As a result, significant seat dimensions, such as insert width, bolster height, and/or bolster curvature, on the subjective seat fit (e.g., loose-fit, right-fit, and tight-fit) were quantified. The developed models showed 98% overall classification accuracy throughout the cross-sectional planes. The models promote a digital design process of an automobile seat, which would increase the efficiency of the process and reduce the development costs.

Excavator driver seat occupational comfort assessment with Lumbar Support Cushion

The operators of excavators often suffer from dreadful Whole-Body Vibration. Besides, the operators are subject to postural instability which is considered to be a serious occupational health hazard. The main objective of this study is to investigate the role of Lumbar Support Cushion in mitigation of Whole-Body Vibration and postural instability under three different operating conditions such as Front-Manipulator Motion, Swing Motion and Propel-Drive Motion. The obtained Vibration Dose Value reveals a significant difference between the operation cycle (p < 0.001). Moreover, across the operation cycle with Lumbar Support Cushion a significant decrease in Vibration Dose Value (8) is observed on the operator seat-pan and backrest (p < 0.05). Further, the effect of Whole-Body Vibration on physiological stress factors, a significant decrease in systolic blood pressure by 1.26%, pulse rate by 2.75% and Rate Pressure Product by 4%, is observed with the use of Lumbar Support Cushion (p < 0.05) during the operation. The Lumbar Support Cushion helps in promoting a symmetric seating posture, and using Lumbar Support Cushion could help the excavator operator to increase in productivity during shift hour.

Pareto-optimal front for multi-objective optimization of the suspension of a full-vehicle model in the frequency domain

PurposeThis study aims to propose a complete and powerful methodology that allows the optimization of the passive suspension system of vehicles, which simultaneously takes comfort and safety into account and provides a set of optimal solutions through a Pareto-optimal front, in a low computational time.Design/methodology/approachUnlike papers that consider simple vehicle models (quarter vehicle model or half car model) and/or simplified road profiles (harmonic excitation, for example) and/or perform a single-objective optimization and/or execute the dynamic analysis in the time domain, this paper presents an effective and fast methodology for the multi-objective optimization of the suspension system of a full-car model (including the driver seat) traveling on an irregular road profile, whose dynamic response is determined in the frequency domain, considerably reducing computational time.FindingsThe results showed that there was a reduction of 28% in the driver seat vertical acceleration weighted root mean square (RMS) value of the proposed model, which is directly related to comfort, and, simultaneously, an improvement or constancy concerning safety, with low computational cost. Hence, the proposed methodology can be indicated as a successful tool for the optimal design of the suspension systems, considering, simultaneously, comfort and safety.Originality/valueDespite the extensive literature on optimizing vehicle passive suspension systems, papers combining multi-objective optimization presenting a Pareto-optimal front as a set of optimal results, a full-vehicle model (including the driver seat), an irregular road profile and the determination of the dynamic response in the frequency domain are not found.

Predatory journals – Alarming danger to the society

Research and publications have taken the driver's seat in the last decade, especially amongst the Orthopaedic surgeons of India (Vaishya and Lal, 2016 Oct-Dec)1. Doing research and publishing scientific papers is crucial to practice evidence-based medicine and keep updated on the latest developments. It is also a quick method to get recognized in your field by your peers and colleagues. Sometimes, publishing literature is vital to gain positions in the profession and achieve promotions (Patralekh et al., 2021)2. As a result, there is a sudden upsurge in printed literature that is inaccurate or up to the mark. It has become tough to believe the conclusions provided and alter one's clinical practice based on these facts. Hence, before reading a paper, one must learn to assess the journal's quality and its publications. In recent times, there is an upsurge in the number of predatory journals causing harm to the entire research world.

Whole Body Vibration on drivers seat and fender with fully loaded double axle tractor-trailers under different operating conditions

Tractors play an important role in Indian agriculture; it is used for agricultural operations and as a common means of transportation in rural areas. It exposes the drivers and workers sitting on fenders to whole body vibration. which results into back pain, spine degeneration and even spine disc problems. Keeping this in mind a study was carried out to measure the whole body vibration on driver and fender seat with fully loaded double axle tractor-trailer under different operating conditions. Vibration was measured on two terrains (Asphalt, Farm), at three speed (10, 12, 14 km/h on asphalt terrain and 4, 5, 7 km/h on farm terrain, as per ISO-5008 (1979)), in three directions (longitudinal, transverse, and vertical) using tri-axial accelerometers. Data was taken for 120 s each and analyzed using vibration meter and analyzer for three replications of each treatments. Vector sum of vibration and Health Guidance Caution Zone upper and lower limit were obtained for different operating conditions to know the health effect of vibration.

Putting the team in the driver's seat: A meta‐analysis on the what, why, and when of team autonomy's impact on team effectiveness

AbstractAutonomy is a ubiquitous team design feature, which is purported to relate positively to team effectiveness. However, the theoretical link between team autonomy and team effectiveness is not well understood, and previous studies have found inconsistent relations between them. We aim to resolve this incomplete understanding by examining “why” autonomy relates to team effectiveness, “what” aspects of team effectiveness are affected by team autonomy, and “when” the relations vary. To do so, we investigated task‐ and relationship‐focused team functioning as mediators, expanded the construct of team effectiveness beyond just team performance to include attitudes, and tested the moderating effects of task routineness and interdependence. Our meta‐analyses based on 415 effect sizes from 69 studies conducted on approximately 6,035 teams revealed that team autonomy positively relates to both task‐ and relationship‐focused team functioning. The results showed significant indirect effects of autonomy on both team performance and attitudes via both types of team functioning. Task routineness weakened the effect of team autonomy on task‐focused functioning and, ultimately, on team performance and attitudes, while it did not change the effect on relationship‐focused functioning. The influence of team autonomy did not vary by the level of task interdependence. Theoretical and practical implications are discussed.

Evaluations of pretensioner activation in rear impacts

Objective Occupant kinematics and biomechanical responses are assessed with and without pretensioning of normally seated and out-of-position front-seat occupants in rear sled tests. The results are compared to recent studies. Methods Three series of rear sled tests were conducted at 24 and 40 km/h with a 2001 Ford Taurus. Series I consisted of two sled tests with a lap-shoulder belted 50th Hybrid III in the driver seat. Series II included four sled tests with a lap-shoulder belted 50th Hybrid III in both front seats. Two soft foam blocks were added, one was placed on the chest centerline under the shoulder belt and one on the pelvis under the lap belt providing additional webbing. Series III consisted of 8 runs and 16 ATD tests to assess the effect of pretensioning with out-of-positioned (OOP) occupants. The biomechanical responses were normalized with Injury Assessment Reference Values (IARV) for head, neck and chest. Results The ATD kinematics and biomechanical responses were similar in the yielding phase when the occupant was normally seated with and without pretensioning. The rebound displacement was greater with pretensioning in the 40 km/h tests due to the shoulder belt slipping off the shoulder. The hip displacement was similar, irrespective of pretensioning. All biomechanical responses were below IARVs. The highest response was for lower neck extension. The normalized response was at about 32% for the 24 km/h tests, irrespective of pretensioning. It was up to 59% in the 40 km/h tests with pretensioning. With the OOP occupants, there were no differences in the kinematics and biomechanical response with pretensioning. Conclusions Testing of the effect of retractor pretensioning with out-of-position occupants and additional belt webbing in moderate to high-speed rear sled tests shows no effect on occupant kinematics and biomechanical responses. The displacement of the hips in a rear impact depends on the compliance of the seatback and amount of pocketing, the stiffness of the seat frame limiting rearward rotation, and the dynamic friction between the occupant and the seatback.

Effect of Class I–III obesity on driver seat belt fit

Objective Approximately 40% of the U.S. adult population are obese. An issue associated with this trend is proper seat belt fit for obese occupants. This study extends previous research, in which few individuals with high BMI (> 40 kg/m2) were included, by examining the relationship between participant and belt factors on belt fit for drivers with Class I-III obesity. Methods Posture and belt fit of 52 men and women with BMI from 31 to 59 kg/m2 (median 38 kg/m2) were measured in a laboratory vehicle mockup. Five seat belt configurations were achieved by manipulating the belt anchorage locations. Body and belt landmark locations were recorded using a three-dimensional coordinate measuring machine. Results Higher BMI was associated with a lap belt position further forward and higher relative to the pelvis. On average, the lap belt was positioned an additional 32 mm forward and 13 mm above the ASIS with each increasing level of obesity classification. Sex had a small effect after accounting for BMI and stature. The mean fore-aft location of the lap belt was 24 mm more forward for men vs. women and 12 mm higher for women vs. men at the same stature and BMI. On average, women used 50 mm more belt webbing in the lap and 92 mm more in the shoulder vs. men. Conclusions The results suggest that increasing levels of obesity class effectively introduces slack in the seat belt system by routing the belt further away from the skeleton. Because the belt is designed to engage the pelvis during a frontal crash, belt placements that are higher and further forward may increase injury risk by allowing excursions or submarining. Unique to this cohort, sex had an important effect on belt fit measures after taking into account stature and BMI. The participant and belt factors considered explained only about 40% of the variance in belt fit. The remaining variance may be due to preference or exogenous body shape effects. Further research is needed to assess methods for enhanced seat belt fit for people with obesity, including addressing sex differences in belt routing.

Comprehensive assessment of the influence of structural friction in a vehicle suspension on its performance

Decision-making regarding the application of any new structure at the design stage requires in practice that it should be compared with the existing one by many indicators. A special feature of the new design of hydropneumatic suspension is the existence of movable connections (screw and splined) as parts of the hydropneumatic element. The presence of structural friction in movable connections requires, in particular, an assessment of the impact of this friction on the process of oscillations when moving through crossed terrain based on comparative analysis. The comprehensive estimate chosen for comparison includes operational properties in terms of ergonomics (smooth movement) and adhesion to the support surface (effort in the contact of wheels with the support surface). The results of a theoretical study involving a vehicle with parameters (weight, dimensions) close to armored personnel carriers BTR70, BTR80, but with hydropneumatic suspensions, demonstrated that when driving on crossed terrain with speeds up to 65 km/h there is a significant reserve in terms of ergonomics. Regardless of the presence (absence) of structural friction, at friction coefficients of up to 0.085. When moving on the surface with large irregularities, the reserve for the maximum allowable (3 g) acceleration in a driver seat is 4.708 times (there is no structural friction) and 3.768 times (structural friction is present). When moving on the surface with small irregularities, the reserve for the maximum permissible (0.5 g) acceleration in a driver seat is 2.093 times (there is no structural friction) and 2.616 times (structural friction is present). Under the most dangerous modes of movement (at the highest speeds) when driving over small irregularities, the presence of structural friction has a positive effect both in terms of ergonomics and stability. Thus, when driving at a speed of 65.679 km/h, the minimum clutch margin is 1.4 times greater, and the acceleration is 1.249 times smaller

Big Dig for Kids Puts Children in the Driver's Seat

Big Dig for Kids Puts Children in the Driver's Seat

Deferral and the Dream

Deferral and the Dream

The antigen-binding moiety in the driver's seat of CARs.

Immuno‐oncology has been at the forefront of cancer treatment in recent decades. In particular immune checkpoint and chimeric antigen receptor (CAR)‐T cell therapy have achieved spectacular results. Over the years, CAR‐T cell development has followed a steady evolutionary path, focusing on increasing T cell potency and sustainability, which has given rise to different CAR generations. However, there was less focus on the mode of interaction between the CAR‐T cell and the cancer cell; more specifically on the targeting moiety used in the CAR and its specific properties. Recently, the importance of optimizing this domain has been recognized and the possibilities have been exploited. Over the last 10 years—in addition to the classical scFv‐based CARs—single domain CARs, natural receptor‐ligand CARs, universal CARs and CARs targeting more than one antigen have emerged. In addition, the specific parameters of the targeting domain and their influence on T cell activation are being examined. In this review, we concisely present the history of CAR‐T cell therapy, and then expand on various developments in the CAR ectodomain. We discuss different formats, each with their own advantages and disadvantages, as well as the developments in affinity tuning, avidity effects, epitope location, and influence of the extracellular spacer.

Prediction model for autopsy diagnosis of driver and front passenger in fatal road traffic collisions

Road traffic collisions (RTC) analysis is almost a daily activity in many autopsy room. Especially when analyzing an RTC with multiple occupants in the car, it can be necessary to distinguish driver from front seat passenger in order to provide the judicial authority with elements useful to understand and to prove who was driving, considering the criminal and civil responsabilities that may derive from it. Despite this, it is beyond doubt that there is enormous difficulty in providing such information. The aim of this paper is then to evaluate whether it is possible to differentiate driver and front seat passenger in case of fatal collisions using a mathematical model based on injury pattern alone. Autopsy reports concerning 90 drivers and 60 front-seat passengers were analyzed. Statistical analysis was used to detect injuries capable of discriminating between driver and passenger, considering skin, skeletal and visceral injuries. Results show that certain skin injuries, fractures and internal organ lesions are possibly associated with drivers and front seat passenger status and the overall injury pattern seems to be able to provide useful information. A mathematical model is presented. The process to distinguishing driver from front seat passenger following fatal motor vehicle collision may use multiple sources of information, including autopsy injury pattern analysis.

A genetic screen for regulators of muscle morphogenesis in Drosophila.

The mechanisms that determine the final topology of skeletal muscles remain largely unknown. We have been developing Drosophila body wall musculature as a model to identify and characterize the pathways that control muscle size, shape, and orientation during embryogenesis. Our working model argues muscle morphogenesis is regulated by (1) extracellular guidance cues that direct muscle cells toward muscle attachment sites, and (2) contact-dependent interactions between muscles and tendon cells. While we have identified several pathways that regulate muscle morphogenesis, our understanding is far from complete. Here, we report the results of a recent EMS-based forward genetic screen that identified a myriad of loci not previously associated with muscle morphogenesis. We recovered new alleles of known muscle morphogenesis genes, including back seat driver, kon-tiki, thisbe, and tumbleweed, arguing our screen had the depth and precision to uncover myogenic genes. We also identified new alleles of spalt-major, barren, and patched that presumably disrupt independent muscle morphogenesis pathways. Equally as important, our screen shows that at least 11 morphogenetic loci remain to be mapped and characterized. Our screen has developed exciting new tools to study muscle morphogenesis, which may provide future insights into the mechanisms that regulate skeletal muscle topology.

Influence of retractor and anchor pretensioning on dummy responses in 40 km/h rear sled tests

Objective This study compared dummy kinematics and biomechanical responses with and without retractor pretensioning in a severe rear sled test. It compliments an earlier study with buckle pretensioning. Methods Three rear tests were run at 40 km/h (25 mph) delta V with a lap-shoulder belted Hybrid III 50th male dummy on a 2013-18 Ford Escape driver seat and belt restraint. One test was with the lap-shoulder belts only, a second with retractor and anchor pretensioning and a third with only retractor pretensioning. The head, chest and pelvis were instrumented with triaxial accelerometers. The upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Lap belt load was measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared to determine the influence of retractor belt pretensioning. Results The dummy kinematics and biomechanical responses were essentially similar with and without retractor or retractor and anchor pretensioning in rear sled tests. There was an initial spike in lap belt load with pretensioning, but it did not result in different dummy head, neck or chest responses. In the tests, the dummy moved rearward away from the shoulder belt. The belts were tightened with the rapid pull on the webbing by pretensioning. The dummy loaded the seat, which yielded rearward restraining its motion. There was no significant effect of pretensioning on the dynamics of the dummy until late in rebound. Conclusions There were no significant differences in dynamics of the Hybrid III with and without retractor or retractor and anchor pretensioning in a 40 km/h (25 mph) rear sled test. Belt pretensioning did not influence biomechanical responses in the rear impact because the seat supported the dummy.