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Secondary blast injuries may result from high-velocity projectile fragments which ultimately increase medical costs, reduce active work time, and decrease quality of life. The role of skin penetration requires more investigation in energy absorption and surface mechanics for implementation in computational ballistic models. High-speed ballistic penetration studies have not considered penetrating and non-penetrating biomechanical properties of the skin, including radial wave displacement, resultant surface wave speed, or projectile material influence. A helium-pressurized launcher was used to accelerate 3/8″ (9.525 mm) diameter spherical projectiles toward seventeen whole porcine legs from seven pigs (39.53 ± 7.28 kg) at projectile velocities below and above V50. Projectiles included a mix of materials: stainless steel (n = 26), Si3N4 (n = 24), and acetal plastic (n = 24). Tracker video analysis software was used to determine projectile velocity at impact from the perpendicular view and motion of the tissue displacement wave from the in-line view. Average radial wave displacement and surface wave speed were calculated for each projectile material and categorized by penetrating or non-penetrating impacts. Two-sample t-tests determined that non-penetrating projectiles resulted in significantly faster surface wave speeds in porcine skin for stainless steel (p = 0.002), plastic (p = 0.004), and Si3N4 ball bearings (p = 0.014), while ANOVA determined significant differences in radial wave displacement and surface wave speed between projectile materials. Surface wave speed was used to quantify mechanical properties of the skin including elastic modulus, shear modulus, and bulk modulus during ballistic impact, which may be implemented to simulate accurate deformation behavior in computational impact models. [ABSTRACT FROM AUTHOR]

A large body of evidence demonstrates that resistance training has been ineffective for improving walking outcomes in adults with neurological conditions. However, evidence suggests that previous studies have not aligned resistance exercise prescription to muscle function when walking. The main aim of this study was to determine whether a training seminar for clinicians could improve knowledge of gait and align resistance exercise prescription to the biomechanics of gait and muscle function for walking. A training seminar was conducted at 12 rehabilitation facilities with 178 clinicians. Current practice, knowledge and barriers to exercise were assessed by observation and questionnaire prior to and immediately after the seminar, and at three-month follow-up. Additionally, post-seminar support and mentoring was randomly provided to half of the rehabilitation facilities using a cluster randomised controlled trial (RCT) design. The seminar led to significant improvements in clinician knowledge of the biomechanics of gait and resistance training, the amount of ballistic (t = -2.38; p = .04) and conventional (t = -2.30; p = .04) resistance training being prescribed. However, ongoing post-seminar support and mentoring was not associated with any additional benefits F(1, 9) = .05, p = .83, partial eta squared = .01. Further, improved exercise prescription occurred in the absence of any change to perceived barriers. The training seminar led to significant improvements in the time spent in ballistic and conventional resistance training. There was no further benefit obtained from the additional post-seminar support. The seminar led to improved knowledge and significantly greater time spent prescribing task-specific resistance exercises. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the learnability and feasibility of a new technique comprising a needle-guidance-system (NGS) for ultrasound-assisted lumbar puncture. Method: Using a randomized crossover study design, 24 medical students were asked to perform an ultrasound-assisted lumbar puncture on a gel phantom using two different techniques that each included a paramedian insertion site. Procedure 1 (P1) used a pre-procedural ultrasound scan to predetermine the ideal insertion point. Procedure 2 (P2) applied a new technique comprising an NGS for performing real-time ultrasound-guided lumbar puncture. Success rates and performance times for both procedures were compared. Participants were also asked to complete a post-study questionnaire, both to quantitatively assess the workload involved and state their personal preferences. Results: In comparison to the pre-procedural scan (P1), the NGS (P2) was associated with a significant increase in the number of successful punctures per participant (5 (P2) [interquartile range: 3.3–5.0] vs. 3 (P1) [interquartile range: 1.3–4.0], p = 0.005), and led to a significant reduction in performance time (118 seconds vs. 80.6 seconds, p < 0.001). In terms of workload perception, NGS use was associated with significantly better performances and lower frustration levels, as rated by students in the post-study questionnaire. Finally, 23/24 participants stated their preference for P2. Conclusion: Our newly-developed technique for real-time ultrasound-guided lumbar puncture proved to be learnable and feasible for novices, and only required a small amount of training. The use of an NGS therefore has the potential to serve as a key feature of the ultrasound-assisted lumbar puncture. [ABSTRACT FROM AUTHOR]

Ballistics literature often focuses on soft tissue injures and projectile trauma to the cranium. Minimal details on the bony characteristics of projectile trauma to the thorax/abdomen regions have been published. This study aims to analyse projectile trauma to the bony trunk region including the ribs, vertebrae, scapula, sternum and the hip bone to form a better understanding of the characteristics and biomechanics of skeletal trauma caused by a projectile and contribute to the existing database on skeletal trauma caused by projectiles. Fourteen cases of documented projectile trauma to the bony regions of the trunk from the Hamman-Todd Human Osteological Collection at the Cleveland Natural History Museum, Ohio were analysed. Of the 14 individuals with gunshot wounds examined, 40 wounds occurred to the bones. Twenty-four injuries to the ribs, 1 ilium, 11 vertebrae, 3 scapulae, and 1 sternum. Fracture patterns, heaving and bevelling can be used to determine the direction of travel of the projectile which can be evident on the ribs, sternum, scapula and ilium. It is critical to understand the wounding patterns associated with projectile trauma to the torso region as this is often targeted, due to being the centre of mass. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the relation between the maximum mean propulsive power (MPP) obtained in the loaded jump squat (JS) and half squat (HS) exercises and functional performances in vertical jumps, 40 m linear speed (VEL) and change-of-direction (COD) tests, using the median split technique. Twenty-two male rugby sevens players from the Brazilian National Olympic Team (Rio-2016) performed vertical jumping tests (squat and countermovement jumps [SJ and CMJ]), JS and HS exercises, COD speed test and sprinting velocity in 40 m, in this order. Based on the results of the MPP in the JS and HS exercises the participants were divided, using the median split, into four groups as follows: higher JS, lower JS, higher HS, and lower HS. Between-group differences in the functional tasks were detected via magnitude-based inferences. The athletes with higher MPP in the JS were capable of jumping higher and sprinting faster (including the COD speed test) than their weaker counterparts. This pattern was not observed in the HS exercise. To conclude, JS was shown to be more connected to sprinting, COD speed and jumping abilities than HS in elite rugby sevens players and should be preferred for assessing and possibly training elite athletes needing to improve speed-power related abilities. [ABSTRACT FROM AUTHOR]

Ballistics is the study of a projectiles motion and can be broken down into four stages: internal, intermediate, external and terminal ballistics. The study of the effects a projectile has on a living tissue is referred to as wound ballistics and falls within terminal ballistics. To understand the effects a projectile has on living tissues the mechanisms of wounding need to be understood. These include the permanent and temporary cavities, energy, yawing, tumbling and fragmenting. Much ballistics research has been conducted including using cadavers, animal models and simulants such as ballistics ordnance gelatine. Further research is being conducted into developing anatomical, 3D, experimental and computational models. However, these models need to accurately represent the human body and its heterogeneous nature which involves understanding the biomechanical properties of the different tissues and organs. Further research is needed to accurately represent the human tissues with simulants and is slowly being conducted. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effect of 4-week unknown vs known loads strength training intervention on power output performance and throwing velocity in junior team handball players. Methods: Twenty-eight junior team-handball players (17.2 ± 0.6 years, 1.79 ± 0.07 m, 75.6 ± 9.4 kg)were divided into two groups (unknown loads: UL; known loads: KL). Both groups performed two sessions weekly consisting of four sets of six repetitions of the bench press throw exercise, using the 30%, 50% and 70% of subjects’ individual 1 repetition maximum (1RM). In each set, two repetitions with each load were performed, but the order of the loads was randomised. In the KL group, researchers told the subjects the load to mobilise prior each repetition, while in the UL group, researchers did not provide any information. Maximal dynamic strength (1RM bench press), power output (with 30, 50 and 70% of 1RM) and throwing velocity (7 m standing throw and 9 m jumping throw) were assessed pre- and post-training intervention. Results: Both UL and KL group improved similarly their 1RM bench press as well as mean and peak power with all loads. There were significant improvements in power developed in all the early time intervals measured (150 ms) with the three loads (30, 50, 70% 1RM) in the UL group, while KL only improved with 30% 1RM (all the time intervals) and with 70% 1RM (at certain time intervals). Only the UL group improved throwing velocity in both standing (4.7%) and jumping (5.3%) throw (p > 0.05). Conclusions: The use of unknown loads has led to greater gains in power output in the early time intervals as well as to increases in throwing velocity compared with known loads. Therefore unknown loads are of significant practical use to increase both strength and in-field performance in a short period of training. [ABSTRACT FROM AUTHOR]

This study aims to investigate the penetration of a projectile into a surrogate human tissue numerically, using Finite Element (FE) simulation. 20% Balistic Gelatin material (BG) is simulated with an elasto-plastic hydrodynamic constitutive law, and then impacted by steel spheres at different velocities. The results from the FE simulations are compared with existing experimental data and other analytical equations from the literature. To our knowledge, this is the first study to investigate a projectile penetration by numerical simulation, and then compare the results with analytical and experimental data from previous studies. This developed model gives encouraging results for further investigations of penetrating impact of projectile in the human body. [ABSTRACT FROM AUTHOR]

Background: Lead-free hunting bullets are an alternative to lead-containing bullets which cause health risks for humans and endangered scavenging raptors through lead ingestion. However, doubts concerning the effectiveness of lead-free hunting bullets hinder the wide-spread acceptance in the hunting and wildlife management community. Methods: We performed terminal ballistic experiments under standardized conditions with ballistic soap as surrogate for game animal tissue to characterize dimensionally stable, partially fragmenting, and deforming lead-free bullets and one commonly used lead-containing bullet. The permanent cavities created in soap blocks are used as a measure for the potential wound damage. The soap blocks were imaged using computed tomography to assess the volume and shape of the cavity and the number of fragments. Shots were performed at different impact speeds, covering a realistic shooting range. Using 3D image segmentation, cavity volume, metal fragment count, deflection angle, and depth of maximum damage were determined. Shots were repeated to investigate the reproducibility of ballistic soap experiments. Results: All bullets showed an increasing cavity volume with increasing deposited energy. The dimensionally stable and fragmenting lead-free bullets achieved a constant conversion ratio while the deforming copper and lead-containing bullets showed a ratio, which increases linearly with the total deposited energy. The lead-containing bullet created hundreds of fragments and significantly more fragments than the lead-free bullets. The deflection angle was significantly higher for the dimensionally stable bullet due to its tumbling behavior and was similarly low for the other bullets. The deforming bullets achieved higher reproducibility than the fragmenting and dimensionally stable bullets. Conclusion: The deforming lead-free bullet closely resembled the deforming lead-containing bullet in terms of energy conversion, deflection angle, cavity shape, and reproducibility, showing that similar terminal ballistic behavior can be achieved. Furthermore, the volumetric image processing allowed superior analysis compared to methods that involve cutting of the soap blocks. [ABSTRACT FROM AUTHOR]

Abstract: The objective of the study was to obtain helmet-to-head contact forces from experiments, use a human head finite element model to determine regional responses, and compare outputs to skull fracture and brain injury thresholds. Tests were conducted using two types of helmets (A and B) fitted to a head-form. Seven load cells were used on the head-form back face to measure helmet-to-head contact forces. Projectiles were fired in frontal, left, right, and rear directions. Three tests were conducted with each helmet in each direction. Individual and summated force- and impulse-histories were obtained. Force-histories were inputted to the human head–helmet finite element model. Pulse durations were approximately 4ms. One-third force and impulse were from the central load cell. 0.2% strain and 40MPa stress limits were not exceeded for helmet-A. For helmet-B, strains exceeded in left, right, and rear; pressures exceeded in bilateral directions; volume of elements exceeding 0.2% strains correlated with the central load cell forces. For helmet-A, volumes exceeding brain pressure threshold were: 5–93%. All elements crossed the pressure limit for helmet-B. For both helmets, no brain elements exceeded peak principal strain limit. These findings advance our understanding of skull and brain biomechanics from helmet–head contact forces. [Copyright &y& Elsevier]

Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (Lf+t; mm) of the femur and tibia of the hind leg, Lf+t = 34.9M0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight. [ABSTRACT FROM AUTHOR]

Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M0.17±0.08 (95% CI), jump take-off angle (A; degrees) scales as A = 52.5M0.00±0.06, and jump energy (E; mJ per jump) scales as E = 1.91M1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (Lf+t; mm) of the femur and tibia of the hind leg, Lf+t = 34.9M0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight. [ABSTRACT FROM AUTHOR]

Abstract: Finite element analysis is frequently used in several fields such as automotive simulations or biomechanics. It helps researchers and engineers to understand the mechanical behaviour of complex structures. The development of computer science brought the possibility to develop realistic computational models which can behave like physical ones, avoiding the difficulties and costs of experimental tests. In the framework of biomechanics, lots of FE models have been developed in the last few decades, enabling the investigation of the behaviour of the human body submitted to heavy damage such as in road traffic accidents or in ballistic impact. In both cases, the thorax/abdomen/pelvis system is frequently injured. The understanding of the behaviour of this complex system is of extreme importance. In order to explore the dynamic response of this system to impact loading, a finite element model of the human thorax/abdomen/pelvis system has, therefore, been developed including the main organs: heart, lungs, kidneys, liver, spleen, the skeleton (with vertebrae, intervertebral discs, ribs), stomach, intestines, muscles, and skin. The FE model is based on a 3D reconstruction, which has been made from medical records of anonymous patients, who have had medical scans with no relation to the present study. Several scans have been analyzed, and specific attention has been paid to the anthropometry of the reconstructed model, which can be considered as a 50th percentile male model. The biometric parameters and laws have been implemented in the dynamic FE code (Radioss, Altair Hyperworks 11©) used for dynamic simulations. Then the 50th percentile model was validated against experimental data available in the literature, in terms of deflection, force, whose curve must be in experimental corridors. However, for other anthropometries (small male or large male models) question about the validation and results of numerical accident replications can be raised. [Copyright &y& Elsevier]

Changes in transmission in Ia afferent and corticospinal pathways have been reported to depend on various factors including task complexity and the phase of movement. Here, we test whether a unilateral voluntary force production task leads to specific changes in both Ia afferent (by the use of the H-reflex technique) and corticospinal (by the use of transcranial magnetic stimulation, TMS) pathways in response to different mechanical conditions. The participants were exposed to either one or three mechanical degrees of freedom (DoF) of an external object while performing a unilateral knee extension movement in a sitting posture. The amplitudes of the m. soleus (SOL) EMG to either type of stimulation were normalized to amplitudes obtained during voluntary tonic contractions at matched background EMG in order to assess movement-related alterations. The results at two phases during movement (initial phase and during task execution) were analyzed. The unstable 1 DoF condition led to elevated co-contraction of SOL and the tibialis anterior muscle. Phase- and movement-related modulations of muscle responses to both types of stimulation were present in both mechanical conditions. However, the stable 1 DoF condition caused a significant facilitation of normalized H-reflexes in the initial phase of movement as compared to 3 DoF (1 DoF: 206%, 3 DoF: 96%, P < 0.001). Conversely, larger normalized amplitudes in response to TMS were found in the initial phase of the 3 DoF condition as compared to 1 DoF (1 DoF: 107%, 3 DoF 160%, P < 0.001). Additionally, during task execution the normalized amplitudes of TMS and H-Reflex testing revealed a relative decrease when compared to the initial phase of movement. It is suggested that presynaptic mechanisms caused the changes in the normalized H-reflexes (and thus in Ia afferent transmission) and that altered normalized responses to TMS reflect changes in corticospinal transmission. Consequently, we reason that the transmission in both pathways is sensitive to the nature of the mechanical interaction and thus to biomechanical task demands. Finally, the voluntary nature of the task might have caused a decisive influence of anticipatory control mechanisms triggered by advance information about the modality of environmental dynamics. [ABSTRACT FROM AUTHOR]

Abstract: Operational restrictions are imposed upon small unmanned aircraft systems weighing up to 15kg, denying them access to the airspace over populated areas because of, for one reason, the dearth of reliable data defining the complex risks associated. Injury biomechanics resulting from blunt ballistic impact is used for small unmanned aircraft system injury potential assessment. Small unmanned aircraft injury potential correlates to the impact kinetic energy and characteristic diameter of its part that contacts the body. The injury severity of small unmanned aircraft can be less than serious in impacts at minimal airspeed that contact the body with their sufficiently blunt part; however, they are capable of inflicting lethal injury, even when impacting at minimal airspeed, if they impact the body with their sharper part. Consequently, for injury minimization the small unmanned aircraft basic operational and physical design criteria are described regarding impact velocity and attitude upon impact, along with the shape of the airframe part that contacts the body. [ABSTRACT FROM AUTHOR]

There is a need to study the biomechanical response of the head to blunt ballistic impact. While the frequency of less-lethal munition impacts to the head may be less than other vital body regions, more serious injuries have been attributed to these impacts. This study aims to establish biomechanical response corridors for the temporo-parietal region for future development of biomechanical surrogate devices. Seven unembalmed post-mortem human subject specimens were exposed to blunt ballistic temporoparietal head impact (103 g, 38 mm diameter impactor) to determine the force-time, deformation-time, and force-deformation responses. Comparisons were made to responses from prior blunt ballistic head impact studies, as well as automotive-related impact studies. Peak forces for impact condition A (19.5 ±2.6 m/s) were 3659 ± 1248 N with deformations at peak force of 7.3 ± 2.] mm. Peak forces for impact condition B (33.6± 1.4 m/s) were 5809 ± 1874 N with deformations at peak force of 9.9 ± 2.6 mm. Seven fractures were produced in the seven specimens. Depressed comminuted fracture types were documented in six of the seven cases. The average stiffness of the temporo-parietal region under blunt ballistic impact was 0.46 ± 0.14 kN/mm. Stiffness results indicate that the response of the temporo-parietal region is similar to the forehead under blunt ballistic loading conditions. In addition, the response is significantly less stiff when compared with temporo-parietal impacts performed in automotive-related studies. These data provide the foundation for future research in the area of blunt ballistic head impact research including the development of biomechanical surrogates and computational models. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Vole captive bolt devices are powder actuated spring guns that are used as a pest control mean. After having triggered the explosion of the blank cartridge by touching a metal ring around the muzzle, the vole is killed by the massive propulsion of the gas jet. Improper use and recklessness while handling these devices may cause severe injuries with the hand of the operator at particular risk. Currently, there are no experimental investigations on the ballistic background of these devices. Methods: An experimental test set-up was designed for measurement of the firing pressure and the dynamic force of the gas jet of a vole captive bolt device. Therefore, a vole captive bolt device was prepared with a pressure take-off channel and a piezoelectric transducer for measurement of the firing pressure. For measurement of the dynamic impact force of the gas jet an annular quartz force sensor was installed on a test bench. Each three simultaneous measurements of the cartridges’ firing pressure and the dynamic force of the blast wave were taken at various distances between muzzle and load washer. Results: The maximum gas pressure in the explosion chamber was up to 1100bar. The shot development over time showed a typical gas pressure curve. Flow velocity of the gas jet was up to 2000m/s. The maximum impact force of the gas jet at the target showed a strong inverse ratio to the muzzle''s distance and was up to 11,500N for the contact shot distance. Energy density of the gas jet for the close contact shot was far beyond the energy density required for skin penetration. Conclusion: The unique design features (short tube between cartridge mouth and muzzle and narrow diameter of the muzzle) of these gadgets are responsible for the high firing pressure, velocity and force of the gas jet. These findings explain the trauma mechanics of the extensive tissue damage observed in accidental shots of these devices. [Copyright &y& Elsevier]