Airgun Research Articles

Validity and reliability of an opto-electric training system in elite and national level ISSF air rifle shooters

The validity of a commonly used optoelectronic training system was examined by identifying the variables that predicted shot score, investigating their ability to discriminate standard, and assessing the predictive variables’ test–retest error. A repeated-measures approach assessed test–retest error, a cross-sectional approach compared standards of shooters and an observational approach examined predictors of shot score. 21 elite and 8 national-standard athletes participated. Multiple linear regression, independent t tests, typical error and coefficient of variation assessed predictors of shot score, discrimination between standards and test–retest error respectively. Stability of aiming predicted 84.2% of the variance in shot score. Six Scatt Expert variables, 10a0, 10a5, 10.0, 10.5, Speed in the last 250 mm, and stability of aiming, discriminated standard (P < 0.05). Test–retest error ranged from a coefficient of variance of 0.72% for 10a0 to 30.69% for Accuracy of Aiming. Stability of aiming had a typical error of 0.55 mm and a coefficient of variance of 13.93%. Results suggest that this optoelectronic training system possesses construct validity if stability of aiming is used as the outcome measure.

Identification of bullets fired from air guns using machine and deep learning methods

Ballistics (the linkage of bullets and cartridge cases to weapons) is a common type of evidence encountered in criminal cases around the world. The interest lies in determining whether two bullets were fired using the same firearm. This paper proposes an automated method to classify bullets from surface topography and Land Engraved Area (LEA) images of the fired pellets using machine and deep learning methods. The curvature of the surface topography was removed using loess fit and features were extracted using Empirical Mode Decomposition (EMD) followed by various entropy measures. The informative features were identified using minimum Redundancy Maximum Relevance (mRMR), finally the classification was performed using Support Vector Machines (SVM), Decision Tree (DT) and Random Forest (RF) classifiers. The results revealed a good predictive performance. In addition, the deep learning model DenseNet121 was used to classify the LEA images. DenseNet121 provided a higher predictive performance than SVM, DT and RF classifiers. Moreover, the Grad-CAM technique was used to visualise the discriminative regions in the LEA images. These results suggest that the proposed deep learning method can be used to expedite the linkage of projectiles to firearms and assist in ballistic examinations.In this work, the bullets that were compared were air pellets fired from both air rifles and a high velocity air pistol. Air guns were used to collect the data because they were more accessible than other firearms and could be used as a proxy, delivering comparable LEAs. The methods developed here can be used as a proof-of-concept and are easily expandable to bullet and cartridge case identification from any weapon.

Characteristics of the far-field source signature and its ghost effect of a marine single air gun

The estimation of the air gun source signature is a crucial topic in marine seismic. Typical approaches such as numerical modelling or near-field measurement-based inversion normally work in practice, but suffer from lack of knowledge on the varying sea surface reflection coefficient, the signature directional consistency and the dynamically changed source geometry. For better understanding of the above uncertainties, real far-field air gun source signatures were acquired. A customized approach combined with sparse f-k transformation and adaptive subtraction is applied to deblend the source signature from the sea-floor reflections. Characteristic of the ghost notch distribution and bubble oscillation period indicate an overall good match to the simulated results, except the latter part due to the unexpected air-leakage. Amplitude decay with incidence-angle increase is observed, indicating that the point-source spherical theory for directional signature estimation may be questionable. The sea-surface reflection coefficient appears time-variant and frequency-dependent which challenges the assumption of flat sea surface in signature estimation. An innovative notional source inversion workflow is adapted to the frequency-dependent reflection coefficient. The notional signature inversed through the adapted approach results in less ghost residuals and weaker spectral notch effect comparing with the normal inversion result, i.e., based on a constant reflection coefficient.

Acute effects of mental recovery strategies in simulated air rifle competitions.

The present study aimed to assess the perception and change of mental and physical fatigue and to examine acute effects of mental recovery strategies in air rifle athletes across simulated competition days with two consecutive competition bouts. We conducted a randomized counterbalanced crossover study. 22 development air rifle athletes (Mage = 17.77 ± 4.0) of a regional squad participate in the study. The Short Recovery and Stress Scale (SRSS), perception of mental fatigue, physical fatigue, concentration and motivation as well as differential Ratings of Perceived Exertion (RPE) were used to assess recovery-stress states and fatigue states. During a recovery break, participants underwent two mental recovery strategies (powernap, systematic breathing) or a control condition. Total shooting scores were recorded for both competition bouts. Study results revealed a significant increase of post ratings for mental (p < .001) and physical fatigue (p < .001) for both competition bouts. The correlation coefficient between change in mental and physical fatigue for both competitions revealed a shared variance of 7.9% and 18.6%, respectively. No significant group-based acute effects of the use of mental recovery strategies on shooting performance, and psychological and perceptual measures were found. On an individual level, results illustrated statistical relevant improvements of shooting performance after powernapping or systematic breathing. Mental and physical fatigue increased and accumulated across a simulated air rifle competition and mental fatigue emerged as a separate construct from physical fatigue. The use of strategies to accelerate mental recovery on an individual level (e.g., powernap, systematic breathing) may be a first step to manage a state of mental fatigue, but further studies on mental recovery strategies in an applied setting are needed.

An HMM-DNN-Based System for the Detection and Classification of Low-Frequency Acoustic Signals from Baleen Whales, Earthquakes, and Air Guns off Chile

Marine passive acoustic monitoring can be used to study biological, geophysical, and anthropogenic phenomena in the ocean. The wide range of characteristics from geophysical, biological, and anthropogenic sounds sources makes the simultaneous automatic detection and classification of these sounds a significant challenge. Here, we propose a single Hidden Markov Model-based system with a Deep Neural Network (HMM-DNN) for the detection and classification of low-frequency biological (baleen whales), geophysical (earthquakes), and anthropogenic (air guns) sounds. Acoustic data were obtained from the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization station off Juan Fernandez, Chile (station HA03) and annotated by an analyst (498 h of audio data containing 30,873 events from 19 different classes), and then divided into training (60%), testing (20%), and tuning (20%) subsets. Each audio frame was represented as an observation vector obtained through a filterbank-based spectral feature extraction procedure. The HMM-DNN training procedure was carried out discriminatively by setting HMM states as targets. A model with Gaussian Mixtures Models and HMM (HMM-GMM) was trained to obtain an initial set of HMM target states. Feature transformation based on Linear Discriminant Analysis and Maximum Likelihood Linear Transform was also incorporated. The HMM-DNN system displayed good capacity for correctly detecting and classifying events, with high event-level accuracy (84.46%), high weighted average sensitivity (84.46%), and high weighted average precision (89.54%). Event-level accuracy increased with higher event signal-to-noise ratios. Event-level metrics per class also showed that our HMM-DNN system generalized well for most classes but performances were best for classes that either had a high number of training exemplars (e.g., generally above 50) and/or were for classes of signals that had low variability in spectral features, duration, and energy levels. Fin whale and Antarctic blue whale song and air guns performed particularly well.

Simultaneous tracking of multiple whales using two fiber-optic cables in the Arctic

Climate change is impacting the Arctic faster than anywhere else in the world. As a response, ecosystems are rapidly changing. As a result, we can expect rapid shifts in whale migration and habitat use concurrent with changes in human patterns. In this context, responsible management and conservation requires improved monitoring of whale presence and movement over large ranges, at fine scales and in near-real-time compared to legacy tools. We demonstrate that this could be enabled by Distributed Acoustic Sensing (DAS). DAS converts an existing fiber optic telecommunication cable into a widespread, densely sampled acoustic sensing array capable of recording low-frequency whale vocalizations. This work proposes and compares two independent methods to estimate whale positions and tracks; a brute-force grid search and a Bayesian filter. The methods are applied to data from two 260 km long, nearly parallel telecommunication cables offshore Svalbard, Norway. First, our two methods are validated using a dedicated active air gun experiment, from which we deduce that the localization errors of both methods are 100 m. Then, using fin whale songs, we demonstrate the methods' capability to estimate the positions and tracks of eight fin whales over a period of five hours along a cable section between 40 and 95 km from the interrogator unit, constrained by increasing noise with range, variability in the coupling of the cable to the sea floor and water depths. The methods produce similar and consistent tracks, where the main difference arises from the Bayesian filter incorporating knowledge of previously estimated locations, inferring information on speed, and heading. This work demonstrates the simultaneous localization of several whales over a 800 km area, with a relatively low infrastructural investment. This approach could promptly inform management and stakeholders of whale presence and movement and be used to mitigate negative human-whale interaction.

Orbitocranial Penetration of Ball Bearing Gun Trauma: A Prospective Human Cadaveric Study.

Objective We completed a prospective human cadaveric study to determine the ability of a ball bearing (BB) pellet to penetrate the orbit and/or surrounding structures. Methods A single trained sergeant officer discharged an alloy steel air rifle to eight cadaver orbits from four adult human cadaver heads. Five BB pellets each were aimed at three locations (caruncle, upper eyelid, or lower eyelid) at 10 cm and 1 m, and then less specifically, at the orbital region for 3- and 5-m distances. Computed tomography (CT) of the cadaver heads was performed. Final locations of BB pellets are divided into three categories: intracranial, surrounding orbital structures including the pterygopalatine fossa and infratemporal fossa, and orbit. Results Of 40 BB pellets, 37 penetrated soft tissue and were visualized on CT: 19 (51%) rested in the intracranial space, 17 (46%) in surrounding orbital structures, and 1 (3%) within the orbit. The deepest position of a pellet was in the parietal lobe, and most superficial location anterior to the frontal bone. Pellets discharged from 1 m were more likely to rest in the intracranial space compared with those from 10 cm ( p < 0.001), 3 m ( p = 0.011), and 5 m ( p = 0.004). The distance of discharge was associated with final pellet location ( p = 0.001). Conclusion BB guns should be considered dangerous and potentially deadly when aimed at the orbit. Although the thick calvarium can protect the intracranial space from BB penetration, the orbit may be a vulnerable entry point with relatively low resistance, allowing penetration of the intracranial and periorbital spaces.

Ballistic response of sandwich shell panels: A comparative study

The present work was carried out to explore the impact response of hemispherical (HSS), cylindrical (CSS) and flat sandwich structures (FSS) subjected to high-velocity impact through experimental and numerical simulations. All three-sandwich structures comprised of Al 1100-H12 face skins and Al -3003 H12 honeycomb core. For the direct comparison, the radius and thickness of all three-sandwich structures were kept identical. The high velocity impact tests were performed by using a pneumatic air gun. The hemispherical and conical shape projectiles were impacted typically at the centre (axis) of the sandwich structures with varying impact velocity. The finite element simulations were carried out through commercially available software Abaqus/explicit. The numerically obtained test results were validated through the experimental results to check the accuracy of the modelling. The response of all three structures was examined by comparing their ballistic resistance, failure mechanics and energy absorption characteristics. In addition, the parametric study was conducted numerically by changing the face skin thickness, cell length and cell wall thickness to find out their influence on the impact response of all three structures. The results revealed that the hemispherical structures showed higher impact resistance in terms of higher ballistic limit velocity and energy absorption. The ballistic limit of the HSS structure was 14.6% and 36.5% higher than the CSS and FSS structure respectively against hemispherical nosed projectile whereas the corresponding value against conical projectile was 9.9% and 20.6% respectively.

Acoustic field characteristics of seismic surveys in the shallow water environment of the Bohai Sea

AbstractAir gun arrays are designed to generate strong energy pulses of less than 100 Hz for offshore oil and gas exploration. In shallow seas, due to the directivity of air gun arrays, the complex propagation conditions and the limitations of acquisition methods, it is difficult to accurately evaluate the spatial time and frequency transmission characteristics of airguns. To alleviate the existing lack of knowledge about the transmission characteristics of air gun pulses in the shallow waters of the Bohai Sea, we analysed three‐dimensional ocean bottom cable seismic data collected during a seismic survey in the Bohai Sea, China, in June 2017, which were used to evaluate the reception level, frequency domain characteristics and spatial distribution characteristics within a 5.55 × 5.575 km area. The results showed that in shallow water, multipath propagation causes downfrequency chirplike sounds and an increased sound field. Within 0.3 km, the transmission model follows a cylindrical diffusion, and the sound loss rate decreases as the transmission distance increases until reaching 8 km. Signal capture by the sound channel results in a high transmission loss frequency band, whereas multimode interference weakens the transmission loss. The gun array directivity and the transmission channel are the two main factors affecting the acoustic field. This research provides an improved understanding of the acoustic field of airguns in the Bohai Sea, which can benefit the acoustic modelling of air gun arrays, the design of future seismic exploration projects and the conservation of marine life.

Numerical investigation on muzzle flow characteristics for small combustion chamber with embedded propelled body

Achieving a smaller size and lighter weight without affecting the launch performance is an important goal in the design of special launch equipment systems such as micro air vehicles and gun propulsion systems. An embedded structure is applied to small chamber systems to save launch space. This paper aims to illustrate the launch performance and muzzle flow characteristics of the embedded structure. The mathematical model of the launch process with a two-stage ignition is established. The muzzle flow model is used to simulate the launch process. The numerical method is verified by experiment. Numerical results indicate that a 21.1% space saving and a 4.2% muzzle velocity increase can be achieved by the embedded structure. The effect of the embedded structure on the muzzle flow is investigated. In the launch process, the Mach disk of the traditional structure travels farther, but that of the embedded structure catches up due to the greater velocity. The pressure oscillation of the embedded structure is larger, but the range of the oscillation is smaller. In the development process, compared with the traditional structure, the main parameters of the embedded structure, such as pressure and Mach number, are greater, which may lead to the launch risk. The findings will be applied to improve the design of small launchers.

Seasonal Variations of Seismic Travel-Time Changes in Binchuan, Southwestern China, Inferred from Large Volume Air-Gun Source Array Data

AbstractActive sources, especially air-gun sources in the water reservoir, have proven to be powerful tools for detecting regional scale velocity changes. However, the water level change affects the repeatability of the air-gun waveform and, thus, affects the stability of the detection of the velocity changes. This article explores how to make full use of the air-gun signals excited at different water levels from analyzing three years of air-gun data recorded by 20 stations deployed from ∼50 m to ∼25 km from the source. At the same time, by utilizing the poroelastic model, we quantify both vertical and horizontal distances affected by the water level change. More important, supported by the strain data from one borehole strainmeter station, the influence mechanisms of the seasonal variation derived from the three years of air-gun data are also discussed. Results indicate the water level affects the main frequency of the air gun and has a strong influence on the coda wave. When the water level of the reservoir changes abruptly, the dominant effect on the derived delay time change is from the water level change. In this case, the deconvolution method can hardly eliminate the influence of the abrupt water level change. However, when the reservoir's water level changes gently, the delay time varies accordingly rather than inversely with the water level. Other reasons affect the material properties and, thus, influence the derived delay time. The modeled vertical component of poroelastic strain caused by the reservoir water level change is 1×10−7. The observed strain (4×10−7) from the strainmeter is likely associated with thermoelastic strain induced by temperature change. Our results show that although the long-term air-gun signal is affected by water level, there is still much information about changes in the subsurface that is worth mining.

Air guns: An underestimated danger - case presentation, literature review and legal interpretation

Abstract Introduction: The compressed air weapon is a type of arm to which the projectile is propelled due to the compression of air in a sealed chamber. These types of weapons belong to the category of non-lethal weapons and ammunition subject to authorization. However, accidental fatal cases, suicides or even deaths with intention attributed to these types of weapons are described in the literature. Case presentation: We are discussing the case of a 5-year-old boy who, at a picnic with several families, is shot and killed with a compressed air rifle, left unattended. The medical crew arrived at the scene could not save the boy’s life. Necroptic examination revealed a gunshot wound through the heart, with the projectile stuck in the lateral-internal wall of the right ventricle. The projectile identified was a metal type projectile (lead), with a length of 8.5 mm and a diameter of 4.5 mm. Conclusions: Compressed air weapons, although considered non-lethal, have proven over time their extremely dangerous potential through the fatal injuries produced. Raising public awareness, limiting use and enforcing strict legislation could prevent tragic events.

Penetration resistance of ceramic/PUE/GFRP multi-layered composite structure

The impact resistance of multi-layered lightweight composite structures is a hot topic in modern military and national defense. To achieve the goal of lightweight, a composite plate consisting of alumina ceramic/polyurethane elastomer (PUE)/glass fiber reinforced plastic (GFRP) with areal density of 3.6 g/cm2 was designed. The penetration experiment of the composite plate was carried out with a first stage light air gun, and the dynamic response of the composite plate under the impact of a large mass round nose projectile (mass 50 g, velocity 100–450 m/s) was studied by combining finite element simulation. Through analysis and discussion, the failure mode, deformation process, energy absorption effect and impact time of the composite plate during penetration process are determined. It is found that the ballistic limit velocity of the composite plate under this penetration condition is 169 m/s. The ceramic layer plays an important role in the energy consumption of the bullet during penetration and the PUE layer does a major part in the penetration time. The penetration time of the PUE layer is always higher than that of the ceramic layer and accounts for about 50% of the total penetration time. As the bullet velocity increases, the distance between the energy absorption of PUE and ceramic gradually decreases. The energy absorption of PUE, which accounts for 29% of the total mass, can reach 36%, while the energy absorption efficiency of the composite plate gradually decreases and finally reaches 18.7%. Through the damage process, it is found that the failure mode of ceramic is completely different from that of PUE. GFRP acts as an intermediate layer and backplane, which has an effective function in stress wave transmission and energy absorption. Finally, under the same penetration conditions, the ballistic limit velocity and damage of the four target plates are compared. The penetration resistance of composite plate is equivalent or better than that of the metal plate because it has a smaller deformation and damage area.

Alcohol and fatal penetration of the cranium by an airgun pellet—a case study from Poland

BackgroundAirguns with the energy of ejected pellets below 17 J are not considered weapons in Poland, can be purchased without permission, and do not require registration. The mere possession of this kind of airgun does not entail any legal consequences, unless it is used for an unauthorized purpose. Sports and recreational shooting do not have to take place within shooting ranges. However, the improper use of this type of weapon can lead to serious injuries and death. In addition, the impact of high blood alcohol content on pain perception can lead to a lack of awareness of the gunshot.Case presentationA 36-year-old woman died a few hours after a head injury inflicted by a 5.50-mm caliber pellet fired from an air gun. The first pellet penetrated perpendicularly through the left temporal bone to the brain. The gunshot tract of this head wound was 6 cm long and ran horizontally and perpendicularly to the surface of the squamous part of the temporal bone. The tract ran through the skin of the skull, the left temporal muscle, and the squamous part of the temporal bone (where the bone was only 1.5 mm thick). The pellet then penetrated the cerebral dura mater, cerebral pia mater on the borderline of the left temporal and frontal lobes, and left lateral wall of the sphenoidal sinus. The victim did not complain of pain due to a high level of alcohol intoxication (0.35 blood alcohol content). The pellet from the second shot (on the foot) penetrated the right foot and was inflicted by the victim.ConclusionThe victim died not earlier than 3 h after being shot as a result of intracranial injuries that caused hemorrhage. The outcomes of this study indicated that high alcohol content resulted in reduced awareness of the victim and no apparent symptoms of developing intracranial injuries.

Unmanned aerial vehicle strike on a flat plate: Tests and numerical simulations

The incursion of Unmanned Aerial Vehicles (UAVs) into airports often occurs due to the popularity of drones, which may lead to a threat to aircraft flight safety. Therefore, estimating the dynamic impact load caused by drone strikes is essential. This paper proposes a test method with high precision and low cost involving launching of a UAV to impact a flat plate specimen by using an air gun. The test results of UAVs impacting flat plates at different impact velocities, such as the UAV damage deformation captured by a high-speed camera and strain vs time dynamic response curves of plates, were obtained and analysed. At the same time, a corresponding numerical simulation was carried out by using the explicit finite element software LS-DYNA. The predicted damage to the UAV and strain on the flat plate during the strike process were compared with the test results. The overall trend of the simulation results is in good agreement with the test results, at least for the first three milliseconds of the event. This shows that the numerical simulation model established in this paper is reasonable. The UAV numerical method established in the present paper can be used to carry out numerical simulations and evaluations of the collision safety of UAVs against large aircraft and high-value ground targets. The results show that the local deformation of the impacted target is uneven due to the distribution of concentrated mass components such as motors, battery, and camera. As the impact velocity of the UAV increases, all parts of the UAV are seriously damaged and basically in a fragmented state, and the battery is greatly deformed. The interaction between the UAV and the flat plate specimen is approximately 2.7 ms, and the UAV numerical simulation model established in this paper can well simulate the real UAV impact process.

Asymptomatic pellet in the maxillary sinus: Medico-legal perspective.

Air guns used for plinking are weapons with a short range and low velocity. Because of their low velocity, the ammunition usually enters the body without causing any immediate life-threatening complications. Lead toxicity is a potential side effect of a pellet lodged in the body. However, there are cases where blood lead level was below the reference value even after decades of an air gun pellet remaining in the body. We report a case of 40-year-old man whose X-ray of the skull revealed a metallic foreign body that appeared to be an air gun pellet in the maxillary sinus. The patient recalled receiving a gunshot wound to his left cheek ten years ago. The wound healed, the pain subsided, and the patient was symptom-free, so he did not seek medical attention. The present case study illustrates the incidental finding of impacted foreign body and its medico-legal aspects in the Nepalese context.

Clinical Outcomes after Ocular Trauma with Orbeez Gel Pellet Projectiles

Ocular trauma is a leading cause of preventable vision loss worldwide. 1 Negrel A.D. Thylefors B. The global impact of eye injuries. Ophthalmic epidemiology. Sep. 1998; 5: 143-169 Crossref PubMed Scopus (450) Google Scholar In studies examining sports-related ocular injury, paintball and air guns were shown to confer the greatest risk for visual impairment. 2 Haring RS, Sheffield ID, Canner JK, Schneider EB. Epidemiology of Sports-Related Eye Injuries in the United States. JAMA ophthalmology. Dec 1 2016;134(12):1382-1390. Google Scholar More recently, “gel blaster guns” have been used to fire Orbeez (Spin Master; Toronto, Canada) and similar gel pellets made of superabsorbent polymers that, when rehydrated with water, expand to around 6-8 mm in diameter while simultaneously becoming soft and pliable. In 2022, the “Orbeez challenge” began trending on the popular social media platform TikTok (ByteDance; Beijing, China). This consisted of shooting rehydrated gel pellets at people - oftentimes unsuspecting strangers. In contrast to paintballs or air gun pellets, shooting gel pellets was depicted as being relatively safe and harmless due to their soft texture. This is a case series describing ocular injuries observed following trauma from gel pellet projectiles.

Evaluation of roost culling as a management strategy for reducing invasive rose-ringed parakeet (Psittacula krameri) populations

Rose-ringed parakeets (Psittacula krameri) are one of the most widespread invasive avian species worldwide. This species was introduced to the island of Kaua‘i, Hawai‘i, USA, in the 1960s. The rapidly increasing population has caused substantial economic losses in the agricultural and tourism industries. We evaluated the efficacy of a roost culling program conducted by an independent contractor from March 2020 to March 2021. We estimated island-wide minimum abundance was 10,512 parakeets in January 2020 and 7,372 in April 2021. Over 30 nights of culling at four roost sites, approximately 6,030 parakeets were removed via air rifles with 4,415 (73%) confirmed via carcasses retrieval. An estimated average of 45 parakeets were removed per hour of shooter effort. The proportion of adult females removed in 2020 was 1.9 × greater when culled outside of the estimated nesting season. Of the four roosts where culling occurred, the parakeets fully abandoned three and partially abandoned one site. Of the three fully abandoned roosts, an estimated average of 29.6% of birds were culled prior to roost abandonment. The roost culling effort was conducted during the COVID-19 pandemic, when tourist numbers and foot traffic were greatly reduced. It is unknown how public perception of roost culling in public areas may impact future efforts. Findings suggest roost culling can be utilized for management of nonnative rose-ringed parakeet populations when roost size is small enough and staff size large enough to cull entire roosts in no greater than two consecutive nights (e.g., if two shooters are available for three hours per night, roost culling should only be attempted on a roost with ≤ 540 rose-ringed parakeets).

Pneumocephalus and Pneumomediastinum from Compressed Air Injury to Conjunctiva

A 30-year-old healthy man presented with bilateral eye swelling and chest and neck pain after compressed air gun injury to the right eye. He had normal ocular vitals with best-corrected visual acuity (BCVA) 20/30 and intraocular pressure of 17 mmHg by tonometry. Anterior segment examination showed multiple conjunctival lacerations as the only point of entry and loculated subconjunctival emphysema (A). Fundus examination was unremarkable. Air presumably tracked through multiple structures leading to orbital emphysema, pneumocephalus (B), and subcutaneous emphysema causing pneumomediastinum extending to the diaphragm (C-D). He was given erythromycin ointment, ocular lubrication, and systemic antibiotics. At follow-up, BCVA was 20/20 with healed conjunctival abrasions and resolution of systemic sequela (Magnified version of Figure A-D is available online at www.aaojournal.org).

A Comparative Study of the Fatigue of the Lower Extremities According to the Type of Shoes Worn When Firing a 10 m Air Pistol.

The purpose of this study was to compare the differences in shooting performance, physical stability, and lower extremity muscle fatigue in high-level shooters wearing shooting shoes and sports shoes, and to determine the causes. Eight high-level 10 m air pistol shooters wore shooting shoes and sports shoes in a simulated shooting qualification experiment (60 rounds in 75 min) and we recorded shooting scores, pressure centers (COP), and median frequency of muscle fatigue index (MDF). All the data are expressed as mean ± standard deviation and are compared using a paired t-test. Athletes in shooting shoes scored higher than those in sports shoes (p < 0.05); COP moved less in the front-to-back and left-to-right directions for athletes wearing shooting shoes rather than sports shoes; and fewer muscles experienced fatigue, with fatigue also occurring later, for athletes wearing shooting shoes rather than sports shoes. Shooting shoes may reduce the sway of athletes’ center of pressure in the anterior−posterior and left−right directions, enhance postural stability, and result in higher shooting scores. In addition, they may make shooters feel more comfortable and relaxed during long training sessions and competitions.