Ballistic research techniques: visualizing gunshot wounding patterns

International Journal of Legal Medicine - There are difficulties associated with mapping gunshot wound (GSW) patterns within opaque models. Depending on the damage measurement parameters required,...     

Preliminary effect of projectile yaw on extremity gunshot wounding in a cadaveric animal model: a serendipitous study

International Journal of Legal Medicine - Gunshot wounding (GSW) is capable of causing devastating tissue injuries by delivering kinetic energy (KE) through the contact surface area of a...     

Noise-induced hearing loss caused by gunshot in South Korean military service

BACKGROUND: Noise-induced hearing loss is a preventive disease and yet the effective treatment modality has not been established. Acute acoustic traumas caused by an exposure to gunshot noise are common in young South Korean males in military service. Considering the significant lack of awareness on this serious issue as well as the absence of proper protective gear, an in-depth analysis is desperately needed. METHOD: All 3650 soldiers performed regular periodic gunfire exercise without any hearing protective measures. Seven patients with hearing impairment after periodic gunfire visited the aeromedical squadron; all were right-handed males. Six were tested with the K-2 rifle and one was tested with a K-5 revolver. History taking, physical examination, pure-tone audiometry, and impedance audiometry were conducted. In the next periodic gunfire exercise, all 3650 soldiers performed gunfire with unilateral hearing protection. RESULTS: The average outcome of postexposure air conduction thresholds was 6.5 dB in the right ear and 33.1 dB in the left ear. After medical treatment, hearing impairment was much improved; however, tinnitus was not diminished. In the next periodic gunfire exercise, the result of a supplement of unilateral earplug protection proved its effectiveness on acoustic trauma caused by gunfire noise. CONCLUSION: Asymmetry in hearing loss is related to the position of the head during gunfire. A unilateral hearing protection device was enough to protect hearing from gunfire noise. At the same time, it can effectively prevent a potential firearm accident that can be caused by trainees mishearing the instruction of a firearm instructor if both earplugs are worn. Thus, providing a unilateral earplug for protection against acoustic trauma must be taken into serious consideration.     

The effect of leakage on the insulation provided by immersion-protection clothing

The effect of controlled, incremental water leakage on the thermal insulation provided by three immersion-protection assemblies has been measured using a thermal manikin. The results show an average loss of 30% of the initial insulation for a leak of 500 g, 40% for a leak of 1000 g, and nearly 60% for a leak of 3000 g. The assemblies differed only in the thermal insulation layer which consisted of: A. A single thickness of wool (initial immersed insulation 0.63 clo) B. A double thickness of wool (initial immersed insulation 0.79 clo) and C. A layer of polypropylene batting between nylon covers (initial immersed insulation 0.76 clo). Differences between the assemblies in loss of insulation with leakage were small and no evidence was found to support claims that the insulating properties of polypropylene are more resistant to wetting than those of wool. It is considered that the substantial loss of insulation even with small leaks makes it essential that tests of the water-excluding performance of immersion suits are undertaken in realistic conditions rather than in calm water.     

The effect of athletic clothing aerodynamics upon running speed

The purpose of this study was to determine the effect of the wind resistance of athletic clothing upon running speed in sprinting and in distance running. Wind tunnel tests of clothing materials, hair, and shoes show that it is possible to lower the wind resistance of a runner from about 0.5% to over 6% by improved aerodynamics. Mathematical models of sprinting and distance running are developed to predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict the effect of lower wind resistance upon race times. By lowering the wind resistance of a runner 2%, the models predict time savings from 0.01 s in the 100-m dash to 5.7 s in the marathon. This is the equivalent of lead distances of about 0.1 to 31 m. The sprint model may be used to predict the effect of altitude upon running speed. At the altitude of Mexico City, the model predicts an improvement of 0.08 s in 100 m and 0.16 s in 200 m. This is conservative compared to actual time savings. The results show that it is possible to lower the wind resistance significantly by improving clothing or by trimming or covering the hair, and that a small aerodynamic drag reduction can result in a significant performance increase.     

The effect of hand immersion on body temperature when wearing impermeable clothing

The effects of hand immersion on body temperature have been investigated in men wearing impermeable NBC clothing. Six men worked continuously at a rate of approximately 490 J. sec-1 in an environmental temperature of 30 degrees C. Each subject was permitted to rest for a period of 20 minutes when their aural temperature reached 37.5 degrees C, and again on reaching 38 degrees C, and for a third time on reaching 38.5 degrees C (three rest periods in total). Each subject completed three experimental conditions whereby, during the rest periods they either: a. Did not immerse their hands (control). b. Immersed both hands in a water bath set at 25 degrees C. c. Immersed both hands in water at 10 degrees C. Physiological measures of core temperature, skin temperature and heart rate were recorded at intervals throughout the experiment. Measures of mean aural temperature and mean skin temperature were significantly (P less than 0.05) reduced if hands were immersed during these rest periods, compared to non immersion. As a result, the total work time of subjects was extended when in the immersed conditions by some 10-20 minutes within the confines of the protocol. It is concluded that this technique of simple hand immersion may be effective in reducing heat stress where normal routes to heat loss are compromised.     

The use of gelatine in wound ballistics research

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.

     

The effect of clothing on the initial responses to cold water immersion in man

The protection provided by three clothing assemblies against the cold shock response was investigated. Nine healthy male volunteers each undertook three two minute head-out immersions into stirred water at 10 degrees C. The subjects wore a different clothing assembly for each immersion, these were: a) Swimming trunks only; b) Conventional clothing (equivalent to RN No 8s); c) Conventional clothing plus windproof/shower-proof clothing (RN foul-weather clothing Mk III). The cardiac, ventilatory and thermal responses of the subjects were examined before and during the immersions. No significant differences were found between the magnitude of the responses recorded on immersion when conventional clothing or foul-weather clothing were worn. Mean skin temperature was lower (P less than 0.05) and respiratory frequency and minute ventilation were higher (P less than 0.05) on immersion in swimming trunks compared to the other two conditions. It is concluded that when policies for the use of immersion protective clothing are being formulated, consideration should be given to all of the potentially hazardous responses associated with cold water immersion.     

The destabilizing effect of body armour on military rifle bullets

Soft body armour is designed to give protection against fragments and some low velocity bullets but is not designed to stop high velocity rifle bullets. Reports have claimed that soft body armour might disturb the stability of bullets that penetrate it, and that this might increase the size of the lesions. The reason for such an effect might be early yaw of the bullet, so we studied the behaviour of bullets which had passed through soft body armour. A 7.62 × 39 mm AK-47 rifle was fired from a permanent stand using full metal jacketed lead core bullets at a range of 30 m. Soft body armour composed of 14 and 28 layers of aramid fibres (Kevlar) was placed at 90° and 60° to the line of fire. Yaw was measured by the shadowgraph technique and a TERMA Doppler radar. A total of ten shots without body armour, and ten shots with each of the two types of body armour at the two angles were used. The results of the shadowgraph and Doppler radar measurements showed a proportional correlation between the two methods of determining the bullet yaw. The semiquantitative approach of the Doppler radar measurement was in agreement with the more concise measurement using the photographic technique. Velocity loss and loss of spin rate from penetrating 14 or 28 ply Kevlar was negligible. We observed induced instability after penetration of 14 and particularly 28 ply Kevlar, dependence of yaw with respect to the number of layers of Kevlar as well as to the angle of the body armour with respect to the line of fire. Received: 21 August 1996 / Received in revised form: 3 January 1997     

The effect of military load carriage on ground reaction forces

Load carriage is an inevitable part of military life both during training and operations. Loads carried are frequently as high as 60% bodyweight, and this increases injury risk. In the military, load is carried in a backpack (also referred to as a Bergen) and webbing, these combined form a load carriage system (LCS). A substantial body of literature exists recording the physiological effects of load carriage; less is available regarding the biomechanics. Previous biomechanical studies have generally been restricted to loads of 20% and 40% of bodyweight, usually carried in the backpack alone. The effect of rifle carriage on gait has also received little or no attention in the published literature. This is despite military personnel almost always carrying a rifle during load carriage. In this study, 15 male participants completed 8 conditions: military boot, rifle, webbing 8 and 16 kg, backpack 16 kg and LCS 24, 32 and 40 kg. Results showed that load added in 8 kg increments elicited a proportional increase in vertical and anteroposterior ground reaction force (GRF) parameters. Rifle carriage significantly increased the impact peak and mediolateral impulse compared to the boot condition. These effects may be the result of changes to the vertical and horizontal position of the body's centre of mass, caused by the restriction of natural arm swing patterns. Increased GRFs, particularly in the vertical axis, have been positively linked to overuse injuries. Therefore, the biomechanical analysis of load carriage is important in aiding our understanding of injuries associated with military load carriage.     

The effect of training of military skills on performance in cold environment

This study was conducted to evaluate how training for disassembling and assembling a weapon and patrol data message terminal and loading a magazine in different temperatures affected the ability to perform those skills in a cold environment. One group trained six times on separate days in a warm environment (19 degrees C), the second group trained three times in a warm environment and then three times in a cold environment (-15 degrees C), and the third group trained six times in the cold environment. Training first in warm and then in cold shortened performance time by 6% to 28%, in comparison to training only in a warm environment. Also, training in cold made the subjects faster than training in warm. In conclusion, before performing military operations in a cold environment, it is most beneficial to train first in warm and then in cold. Training only in warm produces the lowest level of performance in a cold environment.     

猪后肢枪弹伤致肺远达效应损伤支气管变化与内皮素的关系

目的 探讨猪后肢枪弹伤所致肺远达效应损伤的CT表现特点,支气管变化与内皮素(ET)水平的关系.方法 将14头猪随机采用高速弹射击,建立猪后肢枪弹伤中等程度损伤(软组织贯通伤,M组)和重伤动物模型(骨折,S组),每组7头,分别在致伤前、枪击后3 min、10 min、40 min、6 h各时间点,利用CT技术对动物模型的肺部组织进行观察,测量所观察各级支气管的内径,同时检测血浆中ET的浓度变化.结果 (1) 肺远达效应损伤包括渗出、出血、细支气管炎、肺不张、肺间质改变;(2) 枪击后2组实验猪的支气管内径较枪击前都有不同程度的收缩.在枪击后10 min各级支气管收缩较明显(P＜0.05),内径变化与ET水平变化的趋势具有时间相关性; (3) ET在枪击后呈上升趋势,枪击后各时间点ET水平均较枪击前升高(P＜0.05).结论 猪后肢枪弹伤所致肺远达效应损伤支气管形态变化与ET水平变化在时间上有一致性,ET参与肺远达效应损伤的发展,诱导激活炎性因子产生,从而加重肺部损伤.     

The effect of helmet materials and simulated bone and tissue layers on bullet behaviour in a gelatine model of overmatch penetrating head injury

International Journal of Legal Medicine - 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...     

游离三碘甲状腺原氨酸治疗胸部火器伤后心功能不全的实验研究

目的观察胸部火器伤后游离三碘甲状腺原氨酸(FT     

The effect of sleep deprivation and sustained military operations on near visual performance.

A group of military servicemen were deprived of sleep for 65 h while they carried out a simulated military mission with a high visual workload. Their performance in a series of near vision tests was monitored. In general, the visual system was found to be resilient to the stress of sleep loss, the subjects experiencing mild symptoms of asthenopia (eyestrain). However, after 48 h without sleep there was a reduction in amplitude of convergent fusional reserves and a decrease in contrast sensitivity to a spatial frequency of 6 cycles/degree. A disruption in diurnal rhythms for these parameters was suggested. The results are considered in terms of the maintenance of visual efficiency and comfort with loss of sleep, and have implications for both the military and civilians involved in shift work and long work schedules.