Geoffrey Desmoulin - Profile on Academia.edu (original) (raw)

Papers by Geoffrey Desmoulin

Forensic application of inverse and reverse projection photogrammetry to determine subject location and orientation when both camera and subject move relative to the scene

Forensic Science International, Feb 1, 2022

We present a case study of a mountain bicycle accident captured by the rider's chest-mounted ... more We present a case study of a mountain bicycle accident captured by the rider's chest-mounted action camera. The objective of the investigation was to determine the orientation of the bicycle relative to the ground and the location of the rider's center of gravity relative to the bicycle. The problem faced in the investigation was that the camera was moving relative to the scene and rider, and the bicycle was moving relative to the camera. Inverse photogrammetry was used to determine the location and orientation of the camera relative to the scene. Reverse projection photogrammetry applied to an exemplar bicycle provided an estimate of the location and orientation of the bicycle relative to the camera. The rider's position and orientation relative to the camera were estimated by comparing synchronized side views and chest-mounted action camera views of the rider's movements, recorded during a trail descent prior to the accident.

It is thought that disc degeneration can cause spine related pain. New treatments acting at cellu... more It is thought that disc degeneration can cause spine related pain. New treatments acting at cellular levels in the intervertebral discs (IVD) may offer potential to improve long-term disc health. Hence, optimized loading that induces positive cellular changes in the disc may improve disc health delaying the onset of degeneration, thus delaying the onset of pain. This dissertation evaluates and improves a vibration based spinal intervention called the Khan Kinetic Treatment (KKT) while describing some of its mechanisms of treatment of the intervertebral disc. Objectives of this study are to: 1) test effects of vibration on disc biosynthesis prior to device modifications (KKT_v1); 2) determine vibration conditions that are most effective in positively altering IVD gene expression; 3) implement findings from objective 2 by modifying the spinal intervention (KKT_v2) and repeating tests; and 4) design, build, validate, and experiment with a novel bioreactor so that other tissues may be targeted. It could be concluded that the unmodified interventions (KKT_v1) vibration loading profile did not fall within the influential range that affects the cells of the bovine IVD. Objective 2 results showed that expression of certain extracellular matrix genes were significantly up regulated with specific vibration loading patterns, indicating a potential therapeutic stimulus (10 min. total duration of an equal mix of 16 Hz and a 50-80 Hz frequency sweep at a minimum of 0.4 g amplitude). Objective 3 had KKT_v1's firmware edited to drive the new frequencies found to be most effective in objective 2 making KKT_v2; results of objective 3 showed that expression of certain extracellular matrix genes were significantly up regulated when vibrated with the modified intervention (KKT_v2) indicating a potential therapeutic stimulus of the intervention itself. Objective 4 results confirmed the positive influence of mRNA expression with the new bioreactor by utilizing the optimal vibration patterns identified in objective 2. iv This research has moved past the proof of concept stage as it has been shown that specific vibration conditions (10 min, 16 & 50-80 Hz, 0.4g) can influence the expression of cell genes in the IVD. The novel bioreactor built as a result of chapter 4 allows us to test other tissues, while mimicking in-vivo conditions. This information could be used to construct future experiments in protein expression or in-vivo MRI studies of human IVD.

Modeling human movement and mechanics: thoracic cage

Journal of the Canadian Society of Forensic Science, Aug 20, 2022

Advances in Military Technology, Dec 28, 2018

This study investigates the performance of a shield appliqué technology designed to protect the u... more This study investigates the performance of a shield appliqué technology designed to protect the user from blast injury. This technology was compared against three other ballistic shields of varying mass using a fixed charge configuration. An instrumented anthropomorphic test dummy (ATD) was used along with pressure sensors to determine injury risk. Results showed that lighter shields offered less protection than their heavier counterparts with higher probability of head, chest, arm and leg injuries. Additionally, when comparing the appliqué to a mass-matched shield, relevant loadings were reduced on average by 21 %. Overall, the ballistic shield appliqué technology shows promise for becoming a tool for blast mitigation in the short to medium term.

Applied Ergonomics, Feb 1, 2019

Compare the effectiveness of light, medium and heavy weight Police expandable batons from a perfo... more Compare the effectiveness of light, medium and heavy weight Police expandable batons from a performance and a user perception perspective. Rationale: Police Officers are required to control combative individuals using less lethal tactics in proportion to the threat they face. Officers need to deliver sufficient force quickly and accurately. As such, it is important to select batons that are optimal for both performance and user experience. Methods: Eleven active-duty New York Police Department Officers completed static and dynamic strike testing followed by a questionnaire. Six baton types were tested using different weights and lengths. Results: Peak force, dynamic task speed and accuracy were similar between baton types. Peak impulse, forearm muscle activity, and discomfort were higher with the heaviest baton. Conclusions: Lighter batons can deliver sufficient force to control assailants while imposing lower ergonomic costs and being preferable to the user with no impact on speed or accuracy.

Journal of Forensic Biomechanics, 2014

Background Rebound devices such as trampolines are associated with catastrophic spinal cord injur... more Background Rebound devices such as trampolines are associated with catastrophic spinal cord injuries. Cadaveric studies have reported thresholds for injuries that can be applied to the case of failed acrobatics such as backward somersaults. However, it remains unclear whether falls on rebound surfaces should be expected to cause neurological injuries in the majority of cases or only in unfortunate exceptions. The purpose of the current study is to demonstrate the risk of injury associated with a failed backflip performed on a rebound device such as a trampoline or tumbling trampoline. Methods Backward somersault kinematic data was acquired using subjects fitted with a safety harness. This data was then applied to a testing rig designed to set a Hybrid III Anthropometric Test Dummy (ATD) in rotation and released at precise timing so as to reproduce failed backward somersaults. The ATD was instrumented to measure rotational rate, head acceleration as well as stresses in the lower cervical region. Results The axial compression, shear force and flexion moment measured on average (SD) were respectively 1700 (470) N, 909 (667) N, and 360 (122) Nm while the threshold for bilateral facet joint dislocation (BFD) shown by previous cadaver studies showed a significantly lower threshold (p<0.001). Combined results have shown a likelihood of BFD for failed somersaults on tumbling trampolines ranging from 47 to 99%. Conclusion Failed backward somersaults causing BFD are also likely to cause neurological damage. Therefore, use of rebound devices requires the need for progressive skill achievement; supervision for beginners and the use of additional safety measures must be emphasized to prevent inverted vertical falls resulting in the specific combination of forces necessary to cause BFD.

Journal of Biomechanics, Dec 1, 2009

Epidemiological data at one time was taken to suggest that chronic vibrations-for example operati... more Epidemiological data at one time was taken to suggest that chronic vibrations-for example operating vehicles with low-quality seats-contributed to intervertebral disc degeneration and lower back pain. More recent discussions, based in part upon extended twin studies, have cast doubt upon this interpretation, and question how much of the vibration is actually transmitted to the spine during loading. This review summarizes our recent survey of the current state of knowledge. In particular, we note that current studies are lacking a detailed factorial exploration of frequency, amplitude, and duration; this may be the primary cause for inconclusive and/or contradictory studies. It is our conclusion that vibrations are still an important consideration in discogenic back pain, and further controlled studies are warranted to definitively examine the underlying hypothesis: that chronic vibration can influence IVD cell biology and tissue mechanics.

Puncturing a castle defence: injury biomechanics solution to a homicide investigation case study

International journal of forensic engineering, 2022

Journal of Musculoskeletal Pain, 2007

Objectives: Demonstrate initial results using Khan Kinetic Treatment [KKT™] as a low back pain [L... more Objectives: Demonstrate initial results using Khan Kinetic Treatment [KKT™] as a low back pain [LBP] treatment option. Methods: A self-reported functional assessment, LBP questionnaire, and pain medication dose were used as the outcome measures for 48 matched subjects randomly split into two groups [treatment and control]. The treatment group underwent a treatment period consisting of several individual KKT™ treatments over a few weeks period, while the control group continued conventional treatment. A paired t-test analyzed the functional assessment scores and a two group by two LBP score [positive or non-positive] McNemar's test was used for the LBP questionnaires. Pain medication dose analysis consisted of a two group by two pain medication dose outcome [same or reduced] McNemar's test. Results: Compared to a control group, the treatment group lowered both their self-recorded LBP scores [P < 0.001] and showed a strong positive trend to lower their pain medication dose [P = 0.054]. Only the range of motion assessment questionnaire [range of motion, overall activity, and recreation/work activities] detected changes in these measurements [P = 0.046, P = 0.061, P = 0.052, respectively].

Spine, Apr 15, 2020

Study Design. This article comprises a review of the literature. Objective. The purpose of this s... more Study Design. This article comprises a review of the literature. Objective. The purpose of this study was to elucidate the different types of structural failures exhibited in intervertebral discs (IVDs), summarize their potential causes with respect to mechanical loading conditions and the consequences on cell homeostasis and biomechanics. Summary of Background Data. Many studies have been performed to gain insight into how discogenic back pain progresses in humans both in vitro and in vivo as well as in animal disc models. However, there is a major need to summarize the common factors which initiate the structural failures observed in IVDs and the typical biomechanical changes. This work could help in developing mechanisms aiming to restore the biochemical and biomechanical balance of IVDs. Methods. The different types of structural failures encountered in IVDs were reviewed from published literature. The types of mechanical loading causing these injuries and their physiological and biomechanical consequences were then summarized and linked to ongoing research in this area. Results. The most prominent structural failures associated with IVDs are annulus tears, disc prolapse, endplate damage, disc narrowing, radial bulging, and osteophyte formation in the vertebrae. IVDs were found to be vulnerable to compression, flexion, axial rotation, and complex loading mechanisms through single impact, cyclical, and continuous loading. However, chronic loadings had a more damaging impact on the spine. Significant consequences include imbalance of metabolic enzymes and growth factors, alteration in stress profiles of IVDs and a decrease in mechanical stiffness resulting in impaired biomechanics of the spine. Conclusion. The mode of loading has an important impact on the severity and nature of failures seen in IVDs and the resulting consequences to biomechanics. However, further research is necessary to better understand to the mechanisms that link injury to degeneration and regeneration of IVD tissues.

International journal of forensic engineering, 2015

Multiple incidents of exercise balls bursting during a dumbbell chest press have been reported. T... more Multiple incidents of exercise balls bursting during a dumbbell chest press have been reported. This study quantified the dynamics of the dumbbell chest press performed on such balls and the force applied throughout the exercise cycle. To do so, a well-documented case was replicated using subjects of similar weight, background and athletic ability in the same dumbbell chest press motion. Subjects were instructed to perform repetitions on the exercise balls at both a self-selected pace and at maximal speed using various masses. Dynamic measurements were made to record ball loading, ball loading rate, ball compression, and kinematics of the subjects. Peak loads averaged 2084 N in the case of fast trials and 1815 N for self-selected speed trials. Biomechanical aspects of injury causation and the safe use of exercise balls are discussed throughout the products life cycle; from design and manufacturing to the conditioning professional and athlete end user.

Spine, Jul 1, 2010

Study Design. Bovine caudal intervertebral discs (IVDs) were exposed to free axial vibration for ... more Study Design. Bovine caudal intervertebral discs (IVDs) were exposed to free axial vibration for 10 to 60 minutes at 0 to 0.5g and 0 to 200 Hz. Expression of messenger ribonucleic acid for aggrecan, collagen type I, collagen type II, biglycan, decorin, and versican were assayed, as was apoptosis. Objective. To determine the vibration conditions which are most effective in altering intervertebral disc IVD gene expression. Summary of Background Data. Various studies have suggested widely varying effects of vibration in the IVD, ranging from harmful (increased risk of degeneration) to beneficial (increased analgesia) to neutral (no effect). Methods. Vibration was applied using a custom designed voice coil system, which generated controlled motion in the axial direction. Gene expression in the nucleus pulposus was assessed using RT-PCR and the SYBR green chemistry; apoptosis was assessed using TUNEL staining. Results. Expression of messenger ribonucleic acids for biglycan, collagen type I, collagen type II, decorin, and versican were significantly affected by vibration duration, frequency, and amplitude. Aggrecan was unaffected. Of the 3 factors, amplitude had the largest and widest effect. Conclusion. Expression of extracellular matrix genes was significantly upregulated at high amplitudes (Ͼ0.4 g) in as little as 10 minutes. This may indicate a potential therapeutic stimulus; periodic application of controlled vibration could positively influence matrix maintenance. Further studies on the protein level and long-term effects are warranted.

Journal of Forensic Biomechanics, 2011

The method utilizes equipment designed to determine variables, which influence bruising mechanics... more The method utilizes equipment designed to determine variables, which influence bruising mechanics in living human subjects. The device allows weights to be dropped in a controlled manner onto an impactor lying on the skin surface to measure and analyze bruise mechanics. Measured impact characteristics included peak force, peak pressure, impact displacement, tissue stiffness, impact velocity, pressure impulse, force impulse, kinetic energy and the energy transmitted through the limb. Using kinetic energy, transmitted energy and area in contact with the skin we estimated energy absorbed by the limb and energy density (J/m 2). Only energy absorbed by the limb varied significantly according to logistic regression in the subject that was tested and could therefore be used to determine contusion tolerance in that specific case. Hence, the method may be used to determine mechanical parameters required by a striking implement to induce contusions in a particular individual during crime scene reconstructions. Keywords forensic science; contusion; bruise; biomechanics Purpose A new relatively easy-to-use method to investigate contusion mechanics in living humans has been developed. The method is described in detail so a non-engineer could use the technique to determine the minimum impact energy required by a striking implement to induce contusions of a particular individual during crime scene reconstructions. While we show that the experimental design and methods can be used to investigate various impact factors that affect contusion formation in a single subject, larger sample sizes are required to assess the techniques ability to be generalized if such a goal exists. However, due to the plethora of anatomical, medical and physiological variables that affect contusion formation we think it highly improbable that this technique should or could be used to compare data across the masses. Rather, we envision the method to be used as an investigative tool for individual incident reconstructions and to experimentally determine the effects of a single mechanical, anatomical, medical or physiological variable on the development of contusions.

Gait & Posture, Jun 1, 2011

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Journal of Biomechanics, Dec 1, 2008

Miniature sensors that could measure forces applied by the fingers and hand without interfering w... more Miniature sensors that could measure forces applied by the fingers and hand without interfering with manual dexterity or range of motion would have considerable practical value in ergonomics and rehabilitation. In this study, techniques have been developed to use inexpensive pressure-sensing resistors (FSRs) to accurately measure compression force. The FSRs are converted from pressure-sensing to force-sensing devices. The effects of nonlinear response properties and dependence on loading history are compensated by signal conditioning and calibration. A fourth-order polynomial relating the applied force to the current voltage output and a linearly weighted sum of prior outputs corrects for sensor hysteresis and drift. It was found that prolonged (420 h) shear force loading caused sensor gain to change by approximately 100%. Shear loading also had the effect of eliminating shear force effects on sensor output, albeit only in the direction of shear loading. By applying prolonged shear loading in two orthogonal directions, the sensors were converted into pure compression sensors. Such preloading of the sensor is, therefore, required prior to calibration. The error in compression force after prolonged shear loading and calibration was consistently o5% from 0 to 30 N and o10% from 30 to 40 N. This novel method of calibrating FSRs for measuring compression force provides an inexpensive tool for biomedical and industrial design applications where measurements of finger and hand force are needed.

A 20-mm Neurocuff ™ with 8 sets of tripolar electrodes placed inside longitudinal chambers separa... more A 20-mm Neurocuff ™ with 8 sets of tripolar electrodes placed inside longitudinal chambers separated by insulating ridges [1] was implanted on the left sciatic nerve of 3 cats. Epimysial bipolar EMG electrodes were sutured onto 8 calf muscles. During the next 3-12 mo, force and EMG recruitment properties produced by Neurocuff stimulation were tested under anaesthesia using a 3D force/torque sensor. We found that: 1) Every major muscle supplied by the sciatic nerve can be activated through at least 1 of 8 stimulation channels. 2) Individual Neurocuff channels typically recruit functionally synergistic muscle groups. 3) Single channels produce substantial forces and force recruitment can be well controlled. 4) Forces produced by simultaneous activation of 2 channels sum linearly and predictably, with only modest overlap of axon pools activated by nearby channels.

Multi-disciplinary approach to a use-of-force investigation: case study

International journal of forensic engineering, 2022

International journal of forensic engineering, 2018

Many injuries from helicopter crashes are due to large vertical loads transferred from the ground... more Many injuries from helicopter crashes are due to large vertical loads transferred from the ground, through the aircraft and to the spine of seated occupants. Helicopter manufacturers aim to reduce these loadings through energy-attenuating seats. This report details the methodology used to reconstruct an incident and determine the loads experienced by the passengers, specifically a passenger who sat in the rear right seat of the helicopter and suffered a lumbar burst fracture. (a) analysing the injury; (b) analysing damage to the seat to estimate impact forces, and (c) analysing the mechanism of failure of the landing strut to calculate the impact angle and validate the impact forces at the seat. Once the range of force experienced by the passenger was estimated, the effect of the choice of seat was investigated to determine if this injury could have been avoided using seats commercially available at the time of helicopter manufacturing.

International journal of forensic engineering, 2019

When investigating officer-involved shootings, scientific input provides an unbiased perspective ... more When investigating officer-involved shootings, scientific input provides an unbiased perspective to case evidence that assist both the objectivity and credibility of associated reconstructions. This paper demonstrates this by detailing the reconstruction of a recent shooting where multiple scientific tools and methodology were implemented. In order to differentiate between different possible narratives, tools such as synthetic bones, ballistic soap, human dynamic testing as well as human body numerical modelling were used. These tools show how the narrative available can be tied to the injuries reported through the use of a model supported by simple yet robust laboratory testing. In the exemplary case presented, the method was shown to exonerate the response of a police officer who discharged their weapon in self-defence while trying to subdue a violent suspect.

Canadian Acoustics, Jun 1, 2007

Forensic application of inverse and reverse projection photogrammetry to determine subject location and orientation when both camera and subject move relative to the scene

Forensic Science International, Feb 1, 2022

We present a case study of a mountain bicycle accident captured by the rider's chest-mounted ... more We present a case study of a mountain bicycle accident captured by the rider's chest-mounted action camera. The objective of the investigation was to determine the orientation of the bicycle relative to the ground and the location of the rider's center of gravity relative to the bicycle. The problem faced in the investigation was that the camera was moving relative to the scene and rider, and the bicycle was moving relative to the camera. Inverse photogrammetry was used to determine the location and orientation of the camera relative to the scene. Reverse projection photogrammetry applied to an exemplar bicycle provided an estimate of the location and orientation of the bicycle relative to the camera. The rider's position and orientation relative to the camera were estimated by comparing synchronized side views and chest-mounted action camera views of the rider's movements, recorded during a trail descent prior to the accident.

It is thought that disc degeneration can cause spine related pain. New treatments acting at cellu... more It is thought that disc degeneration can cause spine related pain. New treatments acting at cellular levels in the intervertebral discs (IVD) may offer potential to improve long-term disc health. Hence, optimized loading that induces positive cellular changes in the disc may improve disc health delaying the onset of degeneration, thus delaying the onset of pain. This dissertation evaluates and improves a vibration based spinal intervention called the Khan Kinetic Treatment (KKT) while describing some of its mechanisms of treatment of the intervertebral disc. Objectives of this study are to: 1) test effects of vibration on disc biosynthesis prior to device modifications (KKT_v1); 2) determine vibration conditions that are most effective in positively altering IVD gene expression; 3) implement findings from objective 2 by modifying the spinal intervention (KKT_v2) and repeating tests; and 4) design, build, validate, and experiment with a novel bioreactor so that other tissues may be targeted. It could be concluded that the unmodified interventions (KKT_v1) vibration loading profile did not fall within the influential range that affects the cells of the bovine IVD. Objective 2 results showed that expression of certain extracellular matrix genes were significantly up regulated with specific vibration loading patterns, indicating a potential therapeutic stimulus (10 min. total duration of an equal mix of 16 Hz and a 50-80 Hz frequency sweep at a minimum of 0.4 g amplitude). Objective 3 had KKT_v1's firmware edited to drive the new frequencies found to be most effective in objective 2 making KKT_v2; results of objective 3 showed that expression of certain extracellular matrix genes were significantly up regulated when vibrated with the modified intervention (KKT_v2) indicating a potential therapeutic stimulus of the intervention itself. Objective 4 results confirmed the positive influence of mRNA expression with the new bioreactor by utilizing the optimal vibration patterns identified in objective 2. iv This research has moved past the proof of concept stage as it has been shown that specific vibration conditions (10 min, 16 & 50-80 Hz, 0.4g) can influence the expression of cell genes in the IVD. The novel bioreactor built as a result of chapter 4 allows us to test other tissues, while mimicking in-vivo conditions. This information could be used to construct future experiments in protein expression or in-vivo MRI studies of human IVD.

Modeling human movement and mechanics: thoracic cage

Journal of the Canadian Society of Forensic Science, Aug 20, 2022

Advances in Military Technology, Dec 28, 2018

This study investigates the performance of a shield appliqué technology designed to protect the u... more This study investigates the performance of a shield appliqué technology designed to protect the user from blast injury. This technology was compared against three other ballistic shields of varying mass using a fixed charge configuration. An instrumented anthropomorphic test dummy (ATD) was used along with pressure sensors to determine injury risk. Results showed that lighter shields offered less protection than their heavier counterparts with higher probability of head, chest, arm and leg injuries. Additionally, when comparing the appliqué to a mass-matched shield, relevant loadings were reduced on average by 21 %. Overall, the ballistic shield appliqué technology shows promise for becoming a tool for blast mitigation in the short to medium term.

Applied Ergonomics, Feb 1, 2019

Compare the effectiveness of light, medium and heavy weight Police expandable batons from a perfo... more Compare the effectiveness of light, medium and heavy weight Police expandable batons from a performance and a user perception perspective. Rationale: Police Officers are required to control combative individuals using less lethal tactics in proportion to the threat they face. Officers need to deliver sufficient force quickly and accurately. As such, it is important to select batons that are optimal for both performance and user experience. Methods: Eleven active-duty New York Police Department Officers completed static and dynamic strike testing followed by a questionnaire. Six baton types were tested using different weights and lengths. Results: Peak force, dynamic task speed and accuracy were similar between baton types. Peak impulse, forearm muscle activity, and discomfort were higher with the heaviest baton. Conclusions: Lighter batons can deliver sufficient force to control assailants while imposing lower ergonomic costs and being preferable to the user with no impact on speed or accuracy.

Journal of Forensic Biomechanics, 2014

Background Rebound devices such as trampolines are associated with catastrophic spinal cord injur... more Background Rebound devices such as trampolines are associated with catastrophic spinal cord injuries. Cadaveric studies have reported thresholds for injuries that can be applied to the case of failed acrobatics such as backward somersaults. However, it remains unclear whether falls on rebound surfaces should be expected to cause neurological injuries in the majority of cases or only in unfortunate exceptions. The purpose of the current study is to demonstrate the risk of injury associated with a failed backflip performed on a rebound device such as a trampoline or tumbling trampoline. Methods Backward somersault kinematic data was acquired using subjects fitted with a safety harness. This data was then applied to a testing rig designed to set a Hybrid III Anthropometric Test Dummy (ATD) in rotation and released at precise timing so as to reproduce failed backward somersaults. The ATD was instrumented to measure rotational rate, head acceleration as well as stresses in the lower cervical region. Results The axial compression, shear force and flexion moment measured on average (SD) were respectively 1700 (470) N, 909 (667) N, and 360 (122) Nm while the threshold for bilateral facet joint dislocation (BFD) shown by previous cadaver studies showed a significantly lower threshold (p<0.001). Combined results have shown a likelihood of BFD for failed somersaults on tumbling trampolines ranging from 47 to 99%. Conclusion Failed backward somersaults causing BFD are also likely to cause neurological damage. Therefore, use of rebound devices requires the need for progressive skill achievement; supervision for beginners and the use of additional safety measures must be emphasized to prevent inverted vertical falls resulting in the specific combination of forces necessary to cause BFD.

Journal of Biomechanics, Dec 1, 2009

Epidemiological data at one time was taken to suggest that chronic vibrations-for example operati... more Epidemiological data at one time was taken to suggest that chronic vibrations-for example operating vehicles with low-quality seats-contributed to intervertebral disc degeneration and lower back pain. More recent discussions, based in part upon extended twin studies, have cast doubt upon this interpretation, and question how much of the vibration is actually transmitted to the spine during loading. This review summarizes our recent survey of the current state of knowledge. In particular, we note that current studies are lacking a detailed factorial exploration of frequency, amplitude, and duration; this may be the primary cause for inconclusive and/or contradictory studies. It is our conclusion that vibrations are still an important consideration in discogenic back pain, and further controlled studies are warranted to definitively examine the underlying hypothesis: that chronic vibration can influence IVD cell biology and tissue mechanics.

Puncturing a castle defence: injury biomechanics solution to a homicide investigation case study

International journal of forensic engineering, 2022

Journal of Musculoskeletal Pain, 2007

Objectives: Demonstrate initial results using Khan Kinetic Treatment [KKT™] as a low back pain [L... more Objectives: Demonstrate initial results using Khan Kinetic Treatment [KKT™] as a low back pain [LBP] treatment option. Methods: A self-reported functional assessment, LBP questionnaire, and pain medication dose were used as the outcome measures for 48 matched subjects randomly split into two groups [treatment and control]. The treatment group underwent a treatment period consisting of several individual KKT™ treatments over a few weeks period, while the control group continued conventional treatment. A paired t-test analyzed the functional assessment scores and a two group by two LBP score [positive or non-positive] McNemar's test was used for the LBP questionnaires. Pain medication dose analysis consisted of a two group by two pain medication dose outcome [same or reduced] McNemar's test. Results: Compared to a control group, the treatment group lowered both their self-recorded LBP scores [P < 0.001] and showed a strong positive trend to lower their pain medication dose [P = 0.054]. Only the range of motion assessment questionnaire [range of motion, overall activity, and recreation/work activities] detected changes in these measurements [P = 0.046, P = 0.061, P = 0.052, respectively].

Spine, Apr 15, 2020

Study Design. This article comprises a review of the literature. Objective. The purpose of this s... more Study Design. This article comprises a review of the literature. Objective. The purpose of this study was to elucidate the different types of structural failures exhibited in intervertebral discs (IVDs), summarize their potential causes with respect to mechanical loading conditions and the consequences on cell homeostasis and biomechanics. Summary of Background Data. Many studies have been performed to gain insight into how discogenic back pain progresses in humans both in vitro and in vivo as well as in animal disc models. However, there is a major need to summarize the common factors which initiate the structural failures observed in IVDs and the typical biomechanical changes. This work could help in developing mechanisms aiming to restore the biochemical and biomechanical balance of IVDs. Methods. The different types of structural failures encountered in IVDs were reviewed from published literature. The types of mechanical loading causing these injuries and their physiological and biomechanical consequences were then summarized and linked to ongoing research in this area. Results. The most prominent structural failures associated with IVDs are annulus tears, disc prolapse, endplate damage, disc narrowing, radial bulging, and osteophyte formation in the vertebrae. IVDs were found to be vulnerable to compression, flexion, axial rotation, and complex loading mechanisms through single impact, cyclical, and continuous loading. However, chronic loadings had a more damaging impact on the spine. Significant consequences include imbalance of metabolic enzymes and growth factors, alteration in stress profiles of IVDs and a decrease in mechanical stiffness resulting in impaired biomechanics of the spine. Conclusion. The mode of loading has an important impact on the severity and nature of failures seen in IVDs and the resulting consequences to biomechanics. However, further research is necessary to better understand to the mechanisms that link injury to degeneration and regeneration of IVD tissues.

International journal of forensic engineering, 2015

Multiple incidents of exercise balls bursting during a dumbbell chest press have been reported. T... more Multiple incidents of exercise balls bursting during a dumbbell chest press have been reported. This study quantified the dynamics of the dumbbell chest press performed on such balls and the force applied throughout the exercise cycle. To do so, a well-documented case was replicated using subjects of similar weight, background and athletic ability in the same dumbbell chest press motion. Subjects were instructed to perform repetitions on the exercise balls at both a self-selected pace and at maximal speed using various masses. Dynamic measurements were made to record ball loading, ball loading rate, ball compression, and kinematics of the subjects. Peak loads averaged 2084 N in the case of fast trials and 1815 N for self-selected speed trials. Biomechanical aspects of injury causation and the safe use of exercise balls are discussed throughout the products life cycle; from design and manufacturing to the conditioning professional and athlete end user.

Spine, Jul 1, 2010

Study Design. Bovine caudal intervertebral discs (IVDs) were exposed to free axial vibration for ... more Study Design. Bovine caudal intervertebral discs (IVDs) were exposed to free axial vibration for 10 to 60 minutes at 0 to 0.5g and 0 to 200 Hz. Expression of messenger ribonucleic acid for aggrecan, collagen type I, collagen type II, biglycan, decorin, and versican were assayed, as was apoptosis. Objective. To determine the vibration conditions which are most effective in altering intervertebral disc IVD gene expression. Summary of Background Data. Various studies have suggested widely varying effects of vibration in the IVD, ranging from harmful (increased risk of degeneration) to beneficial (increased analgesia) to neutral (no effect). Methods. Vibration was applied using a custom designed voice coil system, which generated controlled motion in the axial direction. Gene expression in the nucleus pulposus was assessed using RT-PCR and the SYBR green chemistry; apoptosis was assessed using TUNEL staining. Results. Expression of messenger ribonucleic acids for biglycan, collagen type I, collagen type II, decorin, and versican were significantly affected by vibration duration, frequency, and amplitude. Aggrecan was unaffected. Of the 3 factors, amplitude had the largest and widest effect. Conclusion. Expression of extracellular matrix genes was significantly upregulated at high amplitudes (Ͼ0.4 g) in as little as 10 minutes. This may indicate a potential therapeutic stimulus; periodic application of controlled vibration could positively influence matrix maintenance. Further studies on the protein level and long-term effects are warranted.

Journal of Forensic Biomechanics, 2011

The method utilizes equipment designed to determine variables, which influence bruising mechanics... more The method utilizes equipment designed to determine variables, which influence bruising mechanics in living human subjects. The device allows weights to be dropped in a controlled manner onto an impactor lying on the skin surface to measure and analyze bruise mechanics. Measured impact characteristics included peak force, peak pressure, impact displacement, tissue stiffness, impact velocity, pressure impulse, force impulse, kinetic energy and the energy transmitted through the limb. Using kinetic energy, transmitted energy and area in contact with the skin we estimated energy absorbed by the limb and energy density (J/m 2). Only energy absorbed by the limb varied significantly according to logistic regression in the subject that was tested and could therefore be used to determine contusion tolerance in that specific case. Hence, the method may be used to determine mechanical parameters required by a striking implement to induce contusions in a particular individual during crime scene reconstructions. Keywords forensic science; contusion; bruise; biomechanics Purpose A new relatively easy-to-use method to investigate contusion mechanics in living humans has been developed. The method is described in detail so a non-engineer could use the technique to determine the minimum impact energy required by a striking implement to induce contusions of a particular individual during crime scene reconstructions. While we show that the experimental design and methods can be used to investigate various impact factors that affect contusion formation in a single subject, larger sample sizes are required to assess the techniques ability to be generalized if such a goal exists. However, due to the plethora of anatomical, medical and physiological variables that affect contusion formation we think it highly improbable that this technique should or could be used to compare data across the masses. Rather, we envision the method to be used as an investigative tool for individual incident reconstructions and to experimentally determine the effects of a single mechanical, anatomical, medical or physiological variable on the development of contusions.

Gait & Posture, Jun 1, 2011

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Journal of Biomechanics, Dec 1, 2008

Miniature sensors that could measure forces applied by the fingers and hand without interfering w... more Miniature sensors that could measure forces applied by the fingers and hand without interfering with manual dexterity or range of motion would have considerable practical value in ergonomics and rehabilitation. In this study, techniques have been developed to use inexpensive pressure-sensing resistors (FSRs) to accurately measure compression force. The FSRs are converted from pressure-sensing to force-sensing devices. The effects of nonlinear response properties and dependence on loading history are compensated by signal conditioning and calibration. A fourth-order polynomial relating the applied force to the current voltage output and a linearly weighted sum of prior outputs corrects for sensor hysteresis and drift. It was found that prolonged (420 h) shear force loading caused sensor gain to change by approximately 100%. Shear loading also had the effect of eliminating shear force effects on sensor output, albeit only in the direction of shear loading. By applying prolonged shear loading in two orthogonal directions, the sensors were converted into pure compression sensors. Such preloading of the sensor is, therefore, required prior to calibration. The error in compression force after prolonged shear loading and calibration was consistently o5% from 0 to 30 N and o10% from 30 to 40 N. This novel method of calibrating FSRs for measuring compression force provides an inexpensive tool for biomedical and industrial design applications where measurements of finger and hand force are needed.

A 20-mm Neurocuff ™ with 8 sets of tripolar electrodes placed inside longitudinal chambers separa... more A 20-mm Neurocuff ™ with 8 sets of tripolar electrodes placed inside longitudinal chambers separated by insulating ridges [1] was implanted on the left sciatic nerve of 3 cats. Epimysial bipolar EMG electrodes were sutured onto 8 calf muscles. During the next 3-12 mo, force and EMG recruitment properties produced by Neurocuff stimulation were tested under anaesthesia using a 3D force/torque sensor. We found that: 1) Every major muscle supplied by the sciatic nerve can be activated through at least 1 of 8 stimulation channels. 2) Individual Neurocuff channels typically recruit functionally synergistic muscle groups. 3) Single channels produce substantial forces and force recruitment can be well controlled. 4) Forces produced by simultaneous activation of 2 channels sum linearly and predictably, with only modest overlap of axon pools activated by nearby channels.

Multi-disciplinary approach to a use-of-force investigation: case study

International journal of forensic engineering, 2022

International journal of forensic engineering, 2018

Many injuries from helicopter crashes are due to large vertical loads transferred from the ground... more Many injuries from helicopter crashes are due to large vertical loads transferred from the ground, through the aircraft and to the spine of seated occupants. Helicopter manufacturers aim to reduce these loadings through energy-attenuating seats. This report details the methodology used to reconstruct an incident and determine the loads experienced by the passengers, specifically a passenger who sat in the rear right seat of the helicopter and suffered a lumbar burst fracture. (a) analysing the injury; (b) analysing damage to the seat to estimate impact forces, and (c) analysing the mechanism of failure of the landing strut to calculate the impact angle and validate the impact forces at the seat. Once the range of force experienced by the passenger was estimated, the effect of the choice of seat was investigated to determine if this injury could have been avoided using seats commercially available at the time of helicopter manufacturing.

International journal of forensic engineering, 2019

When investigating officer-involved shootings, scientific input provides an unbiased perspective ... more When investigating officer-involved shootings, scientific input provides an unbiased perspective to case evidence that assist both the objectivity and credibility of associated reconstructions. This paper demonstrates this by detailing the reconstruction of a recent shooting where multiple scientific tools and methodology were implemented. In order to differentiate between different possible narratives, tools such as synthetic bones, ballistic soap, human dynamic testing as well as human body numerical modelling were used. These tools show how the narrative available can be tied to the injuries reported through the use of a model supported by simple yet robust laboratory testing. In the exemplary case presented, the method was shown to exonerate the response of a police officer who discharged their weapon in self-defence while trying to subdue a violent suspect.

Canadian Acoustics, Jun 1, 2007