Rat Model of Brain Injury to Occupants of Vehicles Targeted by Land Mines: Mitigation by Elastomeric Frame Designs.

Many victims of blast traumatic brain injury (TBI) are occupants of vehicles targeted by land mines. A rat model of under-vehicle blast TBI was used to test the hypothesis that the ensuing neuropathology and altered behavior are mitigated by vehicle frame designs that dramatically reduce blast-induced acceleration (G force). Male rats were restrained on an aluminum platform that was accelerated vertically at up to 2850g, in response to detonation of an explosive positioned under a second platform in contact with the top via different structures. The presence of elastomeric, polyurea-coated aluminum cylinders between the platforms reduced acceleration by 80% to 550g compared with 2350g with uncoated cylinders. Moreover, 67% of rats exposed to 2850g, and 20% of those exposed to 2350g died immediately after blast, whereas all rats subjected to 550g blast survived. Assays for working memory (Y maze) and anxiety (Plus maze) were conducted for up to 28 days. Rats were euthanized at 24 h or 29 days, and their brains were used for histopathology and neurochemical measurements. Rats exposed to 2350g blasts exhibited increased cleaved caspase-3 immunoreactive neurons in the hippocampus. There was also increased vascular immunoglobulin (Ig)G effusion and F4/80 immunopositive macrophages/microglia. Blast exposure reduced hippocampal levels of synaptic proteins Bassoon and Homer-1, which were associated with impaired performance in the Y maze and the Plus maze tests. These changes observed after 2350g blasts were reduced or eliminated with the use of polyurea-coated cylinders. Such advances in vehicle designs should aid in the development of the next generation of blast-resistant vehicles.

Effects of low speed wind on the recognition/identification and pass-through communication tasks of auditory situation awareness afforded by military hearing protection/enhancement devices and tactical communication and protective systems.

OBJECTIVE: To investigate the effect of controlled low-speed wind-noise on the auditory situation awareness performance afforded by military hearing protection/enhancement devices (HPED) and tactical communication and protective systems (TCAPS). DESIGN: Recognition/identification and pass-through communications tasks were separately conducted under three wind conditions (0, 5, and 10 mph). Subjects wore two in-ear-type TCAPS, one earmuff-type TCAPS, a Combat Arms Earplug in its 'open' or pass-through setting, and an EB-15LE electronic earplug. Devices with electronic gain systems were tested under two gain settings: 'unity' and 'max'. Testing without any device (open ear) was conducted as a control. STUDY SAMPLE: Ten subjects were recruited from the student population at Virginia Tech. Audiometric requirements were 25 dBHL or better at 500, 1000, 2000, 4000, and 8000 Hz in both ears. RESULTS: Performance on the interaction of communication task-by-device was significantly different only in 0 mph wind speed. The between-device performance differences varied with azimuthal speaker locations. CONCLUSIONS: It is evident from this study that stable (non-gusting) wind speeds up to 10 mph did not significantly degrade recognition/identification task performance and pass-through communication performance of the group of HPEDs and TCAPS tested. However, the various devices performed differently as the test sound signal speaker location was varied and it appears that physical as well as electronic features may have contributed to this directional result.

Impact of blue force tracking on combat identification judgments.

OBJECTIVE: We examined the effectiveness of blue force tracking (BFT) decision support for dismounted infantry soldiers. BACKGROUND: Technologies to support combat identification (CID) are rapidly evolving and may be deployable to dismounted soldiers in the future. BFT systems are designed to mitigate the risk of fratricide by supplying positional information regarding friendly units to enhance situation awareness. METHOD: Participants played the role of a dismounted infantry soldier in a first-person perspective gaming environment and made engagement decisions for a series of simulated targets, half of which were enemies and half of which were friends. RESULTS: Participants performed better overall when they were able to use a BFT system than when they performed the task without assistance. When a 10-s latency was added to the updating of position information in the BFT, participants made significantly more false alarms (engaged a friendly target) regardless of whether they knew about the latency. CONCLUSION: The results indicate the promise of a personal BFT device to reduce the likelihood of fratricide by dismounted infantry soldiers. The results, however, also indicate that the effectiveness of such a device can be dramatically reduced when it does not provide real-time data. APPLICATION: Potential applications of this research include development of performance standards for BFT devices and assessment of decision support for dismounted soldiers.

Equipment modification is associated with fewer stress fractures in female Israel border police recruits.

PURPOSE: The study was planned to assess whether combat equipment weight reduction would lead to a reduction in the incidence of stress fractures in female border police infantry recruits taking a 4-month course of basic combat training. METHOD: 213 female border police recruits, 18-19 years of age, undergoing 16 weeks of basic combat training with lighter rifle and lighter closely fitted combat vest, (total 9.4 kg) were followed prospectively for stress fracture (SFx) incidence, compared to a historical control group of 1,210 recruits who trained with traditional equipment (12.5 kg). RESULTS: Equipment modification was associated with a significant reduction in SFx from 18.3% in the control group to 8.0% in the intervention group (p < 0.0001). CONCLUSIONS: This study implies that equipment weight reduction may achieve a significant effect in SFx reduction, Approximating fighting gear to body center of gravity may enhance this effect.

Ingestion of 226Ra from activated paints on military equipment: transfer factors and doses.

The use of 226Ra-activated markings was specific for military equipment some decades ago and the extent of possible internal exposure of former military personnel due to ingestion of 226Ra is an issue of discussion. Whole- or partial-body counts are not sensitive enough to trace an overexposure due to a possible 226Ra uptake four decades ago. Thus retrospective workplace assessments are needed. These are done by wiping tests with linen and skin pads on 226Ra markings on decommissioned military equipment. The contamination investigations are performed in wipe-activity measuring cycles with exponentially increasing numbers of wipes. The activity wiped off does not increase with the number of wipes but levels off instead. Wipes with linen pads are more effective than wipes with skin. The skin-skin activity transfer is investigated by respective wipes too. The maximum committed dose in a typical scenario is calculated under worst case assumptions. For the typical work of 1 y an effective dose of about 70 µSv, and for the bone surface a dose of about 3 mSv, is obtained.

Explosion localization via infrasound.

Two acoustic source localization techniques were applied to infrasonic data and their relative performance was assessed. The standard approach for low-frequency localization uses an ensemble of small arrays to separately estimate far-field source bearings, resulting in a solution from the various back azimuths. This method was compared to one developed by the authors that treats the smaller subarrays as a single, meta-array. In numerical simulation and a field experiment, the latter technique was found to provide improved localization precision everywhere in the vicinity of a 3-km-aperture meta-array, often by an order of magnitude.

Comparative review of marine mammal guidance implemented during naval exercises.

This article reviews the types and effectiveness of marine mammal mitigation measures used during some naval activities worldwide. The three main standard methods used to mitigate the potential impacts of naval sonar sound on marine mammals are (1) time/area planning (of exercises/active sonar use) to avoid marine mammals; (2) implementation of operational procedures (e.g. 'soft start' - where sound levels are gradually increased over time); and (3) monitoring of animals for the purpose of maintaining an 'exclusion zone' around the sound source. Suggestions towards a minimum worldwide mitigation standard are made.

Navy sonar and cetaceans: just how much does the gun need to smoke before we act?

Cetacean mass stranding events associated with naval mid-frequency sonar use have raised considerable conservation concerns. These strandings have mostly involved beaked whales, with common pathologies, including "bubble lesions" similar to decompression sickness symptoms and acoustic traumas. However, other cetacean species have also stranded coincident with naval exercises. Possible mechanisms for the strandings include a behavioral response that causes deep divers to alter their diving behavior, which then results in decompression sickness-like impacts. Current mitigation measures during military exercises are focused on preventing auditory damage (hearing loss), but there are significant flaws with this approach. Behavioral responses, which occur at lower sound levels than those that cause hearing loss, may be more critical. Thus, mitigation measures should be revised. A growing number of international bodies recognize this issue and have urged increasing scrutiny of sound-producing activities, but many national jurisdictions have resisted calls for increased protection.

Mobile chemical detector (AP2C+SP4E) as an aid for medical decision making in the battlefield.

The combination of the AP2C unit with the SP4E kit composes a lightweight mobile detector of chemical warfare agents (CWA), such as nerve and mustard agents, with both vapor- and liquid-sampling capabilities. This apparatus was recently introduced into our military medical units as an aid for detection of CWA on casualties. Importantly, critical information regarding the applicability in the battlefield was absent. In view of the serious consequences that might follow a proclamation of CWA recognition in battlefield, a high false-positive rate positions the utilization of this apparatus as a medical decision tool in question. We have therefore conducted a field experiment to test the false-positive rate as well as analyze possible factors leading to false-positive readings with this device. The experiment was carried out before and after a 4-day army field exercise, using a standard AP2C device, a SP4E surface sampling kit, and a specially designed medical sampling kit for casualties, intended for medical teams. Soldiers were examined at rest, after mild exercise, and after 4 days in the field. The readings with AP2C alone were compared to the combination of AP2C and SP4E and to the medical sampling kit. Various body fluids served as negative controls. Remarkably, we found a false-positive rate of 57% at rest and after mild exercise, and an even higher rate of 64% after the 4-day field exercise with the AP2C detector alone, as compared to almost no false-positive readings with the combination of AP2C and SP4E. Strikingly, the medical sampling kit has yielded numerous false-positive readings, even in normal body fluids such as blood, urine, and saliva. We therefore see no place for using the medical sampling kit due to an unaccepted high rate of false-positive readings. Finally, we have designed an algorithm that uses the entire apparatus of AP2C and SP4E as a reliable validation tool for medical triage in the setting of exposure to nerve agents in the battlefield.

Initial effects of light armored vehicle use on grassland vegetation at Fort Lewis, Washington.

Sustainable use of military training lands requires understanding and prediction of the effects of military vehicles on vegetation. We examined the initial impacts of an 8-wheeled, light armored vehicle (LAV) on grassland vegetation at Fort Lewis, Washington. The LAV drove replicate spiral paths at two starting velocities, 10.3 and 5.1 m s(-1). The disturbed width (width of ground impacted by the tires) increased as turning radius decreased, but was unaffected by vehicle velocity. An inverse-exponential model predicted disturbed width (r(2)=0.68) at all turning radii for both velocities combined. In low-velocity spirals, and for straight tracking (turning radius>40 m) and moderate turns (radius 20-40 m) in high-velocity spirals, all vegetation damage was imprint (plants flattened by wheels). During sharp (radius <20 m), high-velocity turns, most or all of the disturbed width was scraped free of surface vegetation and soil, which was piled to the outside of each tire track. Total plant cover (all species) was not affected by track curvature in low-velocity spirals, but decreased in the order straight tracking>moderate turns>sharp turns in high-velocity spirals. In low-velocity spirals, post-tracking cover of several plant growth forms (non-native species, perennial species, sod-forming grasses) was similar to pre-tracking cover, but in high-velocity spirals, post-tracking cover of these growth forms decreased in the order straight > or =moderate=sharp. Cover of native species and forbs decreased more in high- than in low-velocity spirals, but was unaffected by curvature. Pre- and post-tracking cover of annual species, bunchgrasses, and shrubs was < or =3%. The most severe vegetation damage caused by operation of wheeled LAVs on grasslands is associated with sharp, high-velocity turns.

Offense-defense aspects of nanotechnologies: a forecast of potential military applications.

Potential military applications of nanotechnology will evolve in the next few decades. The implications for both defense and offense should be carefully assessed. Nanotechnology can push major changes in stability, and shape the consequences of future conflict.