Browsing by Author "Mahoney, Peter F."

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    Ballistic impacts on an anatomically correct synthetic skull with a surrogate skin/soft tissue layer
    (Springer, 2017-11-28) Mahoney, Peter F.; Carr, Debra J.; Arm, Richard; Gibb, Iain; Hunt, Nicholas; Delaney, Russ J.
    The aim of this work was to further develop a synthetic model of ballistic head injury by the addition of skin and soft tissue layers to an anatomically correct polyurethane skull filled with gelatine 10% by mass. Six head models were impacted with 7.62 x 39 mm full metal jacket mild steel core (FMJ MSC) bullets with a mean velocity of 652 m/s. The impact events were filmed with high-speed cameras. The models were imaged pre- and post-impact using computed tomography. The models were assessed post impact by two experienced Home Office pathologists and the images assessed by an experienced military radiologist. The findings were scored against real injuries. The entry wounds, exit wounds and fracture patterns were scored positively, but the synthetic skin and soft tissue layer was felt to be too extendable. Further work is ongoing to address this.
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    Development of a synthetic bone and tissue model to simulate overmatch military ballistic head injury
    (2018) Mahoney, Peter F.; Carr, Debra J.; Harrison, K.; Critchley, Richard
    A synthetic bone and tissue head model was built using sequential experiments and tested against impacts with 7.62 x 39 mm MSC ammunition. The key experiment in this series was a forensic reconstruction of two military head injury gunshot wounds. One of the models produced a good representation of the incident. The other was less accurate but did produce a good representation of tangential gunshot wounds. Further work assessed the model against a contact gunshot injury with 5.56 x 45 mm ammunition and looked at the effects of intermediate glass and transparent thermoplastic targets on the wounds produced by 7.62 x 39 mm impacts. Strengths and weaknesses of the model are discussed and further work suggested.
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    Does preliminary optimisation of an anatomically correct skull-brain model using simple simulants produce clinically realistic ballistic injury fracture patterns?
    (Springer, 2017-03) Mahoney, Peter F.; Carr, Debra J.; Delaney, Russ J.; Hunt, N.; Harrison, S.; Breeze, J.; Gibb, I.
    Ballistic head injury remains a significant threat to military personnel. Studying such injuries requires a model that can be used with a military helmet. This paper describes further work on a skull-brain model using skulls made from three different polyurethane plastics and a series of skull ‘fills’ to simulate brain (3, 5, 7 and 10% gelatine by mass and PermaGel™). The models were subjected to ballistic impact from 7.62 × 39 mm mild steel core bullets. The first part of the work compares the different polyurethanes (mean bullet muzzle velocity of 708 m/s), and the second part compares the different fills (mean bullet muzzle velocity of 680 m/s). The impact events were filmed using high speed cameras. The resulting fracture patterns in the skulls were reviewed and scored by five clinicians experienced in assessing penetrating head injury. In over half of the models, one or more assessors felt aspects of the fracture pattern were close to real injury. Limitations of the model include the skull being manufactured in two parts and the lack of a realistic skin layer. Further work is ongoing to address these.
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    The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury
    (Springer Verlag, 2017-08-16) Mahoney, Peter F.; Carr, Debra J.; Miller, D.; Teagle, M.
    The aim of this work was to simulate an overmatch ballistic event against a head wearing a helmet. The experiments were designed to understand how layers of bone (or synthetic bone), synthetic skin and currently used helmet materials influence the behaviour of full metal jacket mild steel core (FMJ MSC) 7.62 × 39 mm bullets, impacting on targets with a mean velocity of 650 m/s. Bullet behaviour within 10% (by mass) gelatine blocks was assessed by measurements made of the temporary cavity within the blocks using high-speed video and of the permanent cavity by dissecting blocks post firing. While ANOVA did not find significant difference at the 0.05 level in the mean values of most of the measurements, there was a significant difference in neck length within the gelatine blocks. The addition of material layers did produce greater variability in the temporary cavity measurements under some of the conditions. One of the synthetic bone polymers with a synthetic skin layer produced similar results within the gelatine blocks to the horse scapulae (with residual tissue) and may be suitable for future ballistic experiments.
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    Investigating the use of concealable and disguised knives
    (Sage, 2017-01) Mahoney, Peter F.; Godhania, K.; Carr, Debra J.
    Knife-carrying and knife crime is a significant issue in many countries. There are a number of knives available for purchase that are designed to be concealable, or that are disguised as everyday objects e.g. combs, pens and belts. In addition, an experienced knife-user will be able to conceal knives around their person. The aim of the work summarised in this paper was to study the concealment and deployment of a range of such weapons and to raise awareness of such threats to the blue-light community (police, ambulance, firefighters and other first responders); allow comment to be made on the effectiveness of various scenarios that a knife-carrier might use to carry and deploy a disguised or concealed knife; and measure the time to deployment of a disguised or concealed knife from different locations on an assailant’s body so that suitable defensive responses can be designed and assessed. High-speed video was used to assist in studying attack sequences and allowed assessment of the speed of attack; this typically varied from 0.5 seconds to 2.3 seconds.
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    A pilot study examining garment severance damage caused by a trained sharp-weapon user
    (2016-07-04) Cowper, E. J.; Mahoney, Peter F.; Godhania, K.; Carr, Debra J.; Harrison, K.
    The pilot study summarized in this paper aimed to raise awareness of a gap that exists in the forensic textile science literature about damage caused to clothing by trained sharp-weapon users. A male trained in the Filipino martial arts discipline of Eskrima performed attack techniques on a physical model of a male torso covered with a 97% cotton/3% elastane knitted T-shirt, that is, a garment commonly worn by males. Fabric severance appearance created by three different, but commonly available, knives was evaluated. High-speed video was used to capture each attack. After each attack the resulting damage to the garment was assessed. This pilot study highlighted differences in severances associated with weapon selection, that is, not all knives resulted in similar patterns of textile damage. In addition, a mixture of stab and slash severances were observed. The findings demonstrated the possible misinterpretation of textile damage under these circumstances compared to damage patterns reported in the existing forensic textile science literature for more commonly occurring knife attacks (i.e. stabbings).
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    The use of gelatine in wound ballistics research
    (Springer, 2018-04-25) Carr, Debra J.; Stevenson, Tom; Mahoney, Peter F.
    Blocks of gelatine are used in both lethality and survivability studies for broadly the same reason, i.e. comparison of ammunition effects using a material that it is assumed represents (some part of) the human body. The gelatine is used to visualise the temporary and permanent wound profiles; elements of which are recognised as providing a reasonable approximation to wounding in humans. One set of researchers aim to improve the lethality of the projectile, and the other to understand the effects of the projectile on the body to improve survivability. Research areas that use gelatine blocks are diverse and include ammunition designers, the medical and forensics communities and designers of ballistic protective equipment (including body armour). This paper aims to provide an overarching review of the use of gelatine for wound ballistics studies; it is not intended to provide an extensive review of wound ballistics as that already exists, e.g. Legal Med 23:21–29, 2016. Key messages are that test variables, projectile type (bullet, fragmentation), impact site on the body and intermediate layers (e.g. clothing, personal protective equipment (PPE)) can affect the resulting wound profiles.
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    Victim’s posture and protective clothing changes the approach in an edged-weapon attack
    (International Ballistics Society, 2017-09-15) Carr, Debra J.; Mahoney, Peter F.; Godhania, K.; Cowper, E.; Malbon, Chris
    Diverse groups of people use edged-weapons (i.e. knives, spears, swords) professionally. The training received affects how the edged-weapon is used and the area of the body targeted. There is a growing body of information available on the internet which is aimed at the training individuals in offensive knife attacks. This poster aims to raise awareness of this issue and highlight how a trained individual modifies an attack sequence depending on their victim’s posture and the protective clothing worn. A male trained in the Filipino martial arts discipline of Eskrima performed attack techniques on a static mannequin covered with a long sleeved upper body garment and leggings, a police custodian helmet and a HG1 + KR1 police body armour. In some simulated attacks the target was also dressed in a police high-visibility tactical vest on top of the body armour. High-speed video was used to capture each simulated attack and the impact location on the torso recorded using ultra-violet sensitive liquid applied to the weapon. Target posture was modified by adjusting the arm position of the mannequin. In a second series of experiments a PermaGel™ male target torso was used so that penetrating damage could be assessed. Data collected identified the change of attack due to victim’s posture and vulnerability of the neck, underarm area and groin