| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Forman, Jason, et al.
(författare)
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Variability in Body Shape, Superficial Soft Tissue Geometry, and Seatbelt Fit Relative to the Pelvis in Automotive Postures—Methods for Volunteer Data Collection With Open Magnetic Resonance Imaging
- 2024
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Ingår i: Journal of Biomechanical Engineering. - 0148-0731 .- 1528-8951. ; 146:3
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Tidskriftsartikel (refereegranskat)abstract
- Variability in body shape and soft tissue geometry have the potential to affect the body’s interaction with automotive safety systems. In this study, we developed a methodology to capture information on body shape, superficial soft tissue geometry, skeletal geometry, and seatbelt fit relative to the skeleton—in automotive postures—using Open Magnetic Resonance Imaging (MRI). Volunteer posture and belt fit were first measured in a vehicle and then reproduced in a custom MRI-safe seat (with an MR-visible seatbelt) placed in an Open MR scanner. Overlapping scans were performed to create registered three-dimensional reconstructions spanning from the thigh to the clavicles. Data were collected with ten volunteers (5 female, 5 male), each in their self-selected driving posture and in a reclined posture. Examination of the MRIs showed that in the males with substantial anterior abdominal adipose tissue, the abdominal adipose tissue tended to overhang the pelvis, narrowing in the region of the Anterior Superior Iliac Spine (ASIS). For the females, the adipose tissue depth around the lower abdomen and pelvis was more uniform, with a more continuous layer superficial to the ASIS. Across the volunteers, the pelvis rotated rearward by an average of 62% of the change in seatback angle during recline. In some cases, the lap belt drew nearer to the pelvis as the volunteer reclined (as the overhanging folds of adipose tissue stretched). In others, the belt-to-pelvis distance increased as the volunteer reclined. These observations highlight the importance of considering both interdemographic and intrademographic variability when developing tools to assess safety system robustness.
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| 3. |
- Gepner, B. D., et al.
(författare)
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Comparison of human body models in frontal crashes with reclined seatback
- 2019
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 293-307
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Konferensbidrag (refereegranskat)abstract
- Reclined seating configurations, relevant to the future of Autonomous Driving Systems is likely to challenge the current state-of-the-art restraint systems. Human body models (HBM) offer an attractive tool to support the design process, however their validity in the reclined scenario remains questionable. The goal of this study is to compare the response of selected HBMs in the frontal, reclined scenario, while utilizing a new prototype restraint system. A sled model with a generic seat, 50 deg seatback recline angle and a prototype 3-point belt system was used in this study. Four different male HBMs were compared, the Global Human Body Model Consortium (GHBMC) simplified occupant model (GHBMC-S), the GHBMC detailed model (GHBMC-D), Total Human Model for Safety SAFER (THUMS-S) model, and THUMS-v5 model. All HBMs showed good pelvis engagement, except GHBMC-D that submarined under the lap belt. Additionally, large differences were observed in pelvis and lumbar spine response between GHBMC and THUMS family models. Since no relevant PMHS data is currently available, it is impossible to evaluate the biofidelity of these models in the reclined scenarios. Evaluating the relative biofidelity of these models can only be accomplished with experimental data capturing detailed 3D skeletal kinematics and all the boundary forces necessary for model evaluation.
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| 4. |
- Gepner, B. D., et al.
(författare)
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Evaluation of GHBMC, THUMS and SAFER Human Body Models in Frontal Impacts in Reclined Postures
- 2022
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2022-September, s. 116-143
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Konferensbidrag (refereegranskat)abstract
- Virtual tools, such as human body models (HBMs), can support advances in vehicle development and restraint system design. The goal of this study is to evaluate selected HBMs against data from recent reclined post-mortem human subject (PMHS) tests. Three HBMs - the Global Human Body Modelling Consortium detailed model v.6.0, Total Human Model for Safety v.6.0, and SAFER HBM v.10 - were used in this study. The models were positioned with respect to the average PMHS position and utlised a previously developed environment model. The HBMs were evaluated comparing belt engagement, boundary forces and displacements (in the seat and belt), and the trajectories of the head, T1, T8, T11, L1, L3, and pelvis. The HBMs' belt engagement, boundary forces and displacements, and X-direction (fore-aft) trajectories were all generally consistent with the PMHS. All HBMs predicted more downward motion of the head and T1 compared to the PMHS. The HBMs also showed rearward pelvis pitch at peak lap belt force, opposite to the PMHS. Some of these differences were associated with differences in flexion of the lumbar spine. This is the first study to provide an in-depth evaluation of multiple reclined HBMs in frontal crashes compared to reclined PMHS.
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| 5. |
- Larsson, Karl-Johan, 1985, et al.
(författare)
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Evaluation of a diverse population of morphed human body models for prediction of vehicle occupant crash kinematics
- 2022
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Ingår i: Computer Methods in Biomechanics and Biomedical Engineering. - : Informa UK Limited. - 1476-8259 .- 1025-5842. ; 25:10, s. 1125 -1155
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Tidskriftsartikel (refereegranskat)abstract
- Morphing can be used to alter human body models (HBMs) to represent a diverse population of occupants in car crashes. The mid-sized male SAFER HBM v9 was parametrically morphed to match 22 Post Mortem Human Subjects, loaded in different configurations. Kinetics and kinematics were compared for the morphed and baseline HBMs. In frontal impacts, the morphed HBMs correlated closer with the kinematics of obese subjects, but lower to small females. In lateral impacts HBM responses were too stiff. This study outlines a necessary evaluation of all HBMs that should be morphed to represent the diverse population in vehicle safety evaluations.
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| 6. |
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| 7. |
- Perez-Rapela, Daniel, et al.
(författare)
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Comparison of the simplified GHBMC to PMHS kinematics in far-side impact
- 2019
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 260-281
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Konferensbidrag (refereegranskat)abstract
- Far-side impacts represent 9.5% of all automobile crashes and 8.3% of all MAIS3+ injuries. This type of event generates loads that challenge current restraint systems by setting the occupant in an inward motion. This complex motion, influenced by a number of restraint and impact parameters, often results in a loss of shoulder-to-belt contact. Existing Anthropomorphic Test Devices show limited ability to represent post-mortem human subject kinematics and sensitivity to restraint and impact parameters. Therefore, Human Body Models can play a fundamental role in understanding human response in this impact scenario. This study compares the simplified GHBMC to previously published post-mortem human subject kinematics and sensitivity to restraint and impact parameters. Results show that, in general, the simplified GHBMC captures lateral excursion in oblique impact conditions but overpredicts in purely lateral impact conditions. The simplified GHBMC shows post-mortem human subject like sensitivities to changes in ?V and the use of pretensioner but no sensitivity to changes in impact direction. The human body model performs similarly to other previously published HBMs and obtains a “good” CORA score. However, the surrogate does not represent post-mortem human subject shoulder-to-belt interaction in all configurations.
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| 8. |
- Perez-Rapela, Daniel, et al.
(författare)
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Comparison of WorldSID to PMHS kinematics in far-side impact
- 2018
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2018-September, s. 630-654
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Konferensbidrag (refereegranskat)abstract
- Far-side impacts represent 9.5% of all automobile crashes and 8.3% of all MAIS3+ injuries. This type of event generates loads that challenge current restraint systems by setting the occupant on an inward motion. This complex motion, influenced by a number of restraint and impact parameters, often results in a loss of shoulder-to-belt contact. Reducing the negative outcomes of this type of crash requires an ATD capable of correctly representing the kinematics and sensitivity to restraint and impact parameters. The WorldSID is the most advanced ATD for injury evaluation in near-side crashes. However, its suitability for far-side scenarios still needs to be evaluated. This study performed a parametric evaluation of the effect of restraint and impact parameters on WorldSID kinematics. A total of 19 tests in six different test configurations were conducted, matching previously published PMHS tests. The ATD motion was tracked with a 3D high-speed motion-capture system. The parameters varied were: the impact severity and direction; D-ring position; pelvic restraint; and seat belt pretensioning. The ATD response and sensitivity to parameters were evaluated and compared to previously published PMHS data. The results show discrepancies in shoulder-belt engagement, head and torso kinematics and sensitivity to initial conditions.
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| 9. |
- Pipkorn, Bengt, 1963, et al.
(författare)
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Forearm Impactor Tests for Development of Injury Risk Assessment Capability
- 2022
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2022-September, s. 430-438
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Konferensbidrag (refereegranskat)abstract
- The forearm is one of the most injured body regions. To enable injury risk assessment a component test method using a novel instrumented forearm impactor was proposed. Impact tests with the forearm were carried out replicating published human subject impact tests. The forearm impactor elbow was mounted to a force transducer and a reaction plate assembly free to move along linear guide rails. The impact load was provided by a guided mass dropped from various heights. The drop heights were selected to generate elbow plate forces including both fractures and no fractures in the published tests. Tests were run with two boundary conditions. The peak elbow plate forces ranged from 1.6 kN to 8.6 kN. The peak axial forces in the internal forearm loadcell varied from 1.9 kN to 9.7 kN. A linear relationship was defined between the forces recorded in the two loadcells for each boundary condition. The linear relationship was developed to aid in translating the published forearm fracture risk curve to facilitate in predicting forearm fracture risk with the forearm impactor in axial impacts with an outstretched hand. The novel instrumented forearm impactor in combination with the injury prediction capability can be used to evaluate forearm fracture risk in hand impacts.
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| 10. |
- Xiao, Sen, et al.
(författare)
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Effect of contact friction between seatbelt and human body model on simulation of rib fracture in frontal impact
- 2016
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Ingår i: Proceedings - 2016 8th International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2016; Macau; China; 11 March 2016 through 12 March 2016. - 2157-1473. - 9781509023127 ; 9 June 2016, s. 255-257
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Konferensbidrag (refereegranskat)abstract
- Seatbelt contact friction coefficient may have some influence on chest injury prediction because it can affect the position of the seatbelt during the impact. The objective was to study the influence of the seatbelt contact friction coefficient on predicted rib fracture outcome in frontal impact. Four simulations of frontal impact sled tests in the same environment were conducted wherein the contact friction coefficient between the seatbelt and the chest model was varied. A noticeable effect was observed wherein increasing friction coefficient which tended to cause a slight decrease in the number of predicted fractures. Despite this, the magnitude of sensitivity was small, suggesting that in the absence of other information arbitrary values of friction coefficient within a reasonable intermediate range may be justified for this specific test condition.
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