Does the transmission of complex wave activity by the skull into the semiliquid brain cause an embolism? Does pressure deform the skull, causing it to squeeze the brain? Is the explosive noise damaging? The flash of light? The majority of soldiers diagnosed with blast-induced neurotrauma have also been hurled or rattled by blast wind.
Is military neurotrauma, then, simply an exotic form of concussion? The tests in Colorado arose from a landmark study by the military of breachers, those soldiers whose job is to set explosives and who for years had been reported to suffer a high incidence of neurological symptoms.
The study, conducted by the U. Marine Corps Weapons Training Battalion Dynamic Entry School, followed instructors and students over a two-week explosives training course.
This suggested that repetitive exposure even to low-level blasts—even over just a two-week period—could be damaging. The breacher study went some way toward bringing blast-induced neurotrauma into focus. Previously, many in the military and medical communities had found it difficult to believe that a low-energy blast could inflict significant injury.
Christian Macedonia Ret. But today some researchers are floating a different theory: that mild TBI may increase vulnerability to certain psychological disorders, possibly accounting for the high rate of such disorders and even suicide among veterans. In the bunker we waited for the smoke to clear, then ventured into still-singed air. Pressure gauges at head and chest level had recorded the back-blast as it bounced off corners and walls. The explosion itself had been preserved on video, which replayed events, at two to three frames a second, that had flashed by at a speed of 14, frames a second—the ignited fuse glowing red-gold in a long, snaking, elegant stem of light, then the gold-black bloom of the explosion: BOOM.
Shot 52 was one of a series intended to cast light on the phenomenon of back-blast, the reflection of blast pressure off a surface. Other studies are examining the length of blast exposure and the frequency and type of blast. On site to lead the analysis was Charles Needham, a world authority on blast physics. Studying a computer-generated graph, he traced the spikes and dips of pressure that oscillated through five cycles before flattening out.
The entire sequence lasted some 65 milliseconds. One hundred milliseconds is the minimum time it takes for a human to react to any stimulus—it had taken less than five milliseconds for the shock wave to hit the gauges on the walls. How a blast is reflected is determined not only by whether a space is square or rectangular, and the ceiling high or low, but also by where the wall studs lie, the number and placement of doors and windows, whether there are gaps or holes in the enclosure, whether there is furniture in the room.
A shock wave bouncing off a rigid surface, whether of thin plaster or of steel, can be more powerful than the original wave. Notoriously, the back-blast reflected off the ground at Hiroshima was more powerful than the actual explosion.
The corners of a room, where one might instinctively seek shelter, are particularly dangerous—as is being the third man in a line of breachers carrying protective shields, which, as it turns out, also reflect shock waves. Every feature in a landscape, every gesture a person makes, shapes a blast event. Encompassing a multitude of variables, calculations about blast events are elaborately difficult, and only in recent years has it been possible to make the kind of models Needham is now devising.
Keen interest in blast effects began in World War I, when the signature mechanism of injury was—as in the wars in Iraq and Afghanistan—blast force, mostly in the form of exploding artillery shells.
The blast was the latest to rock the seat of the internationally recognised government. No group immediately claimed responsibility for the attack, which took place on Tuesday, and authorities said an investigation was ongoing.
Al-Harazi, who works for the United Arab Emirates-based Asharq satellite television channel, was pregnant. Al-Harazi and her child Jawad died at the scene, while her husband, Mahmoud al-Atmi, also a journalist, was seriously wounded and hospitalised in a critical condition, officials said.
Three passersby were also wounded, they added. Additionally, these waves can damage buildings or even knock them flat—often injuring or killing the people inside them. The sudden change in pressure can also affect pressure-sensitive organs like the ears and lungs.
The table at the bottom of this page relates overpressure values to the structural and physiological effects produced. Unlike toxic LOCs , no well-defined guidelines or standards exist to evaluate the overpressure hazard. So, ALOHA uses default overpressure values in pounds per square inch, psi that are based on a review of several widely accepted sources on overpressure and explosions:.
The red, orange, and yellow threat zones indicate the areas where the overpressure is predicted to exceed the corresponding LOC at some time after the release begins. Note that the text accompanying the default LOC values are examples of effects that could occur if that value is exceeded; see the table below for more details about possible damage at various overpressure levels.
The explosive filler can be set off by friction, heat, impact, sparks or flame. If you have a bag full of illegal fireworks and one of them goes off accidentally, you can assume that all of the fireworks in the bag will go off at the same time. A small amount of fireworks going off at the same time in a vehicle can kill everyone who is in that vehicle and scatter parts of the car in all directions.
Some of them have complicated fuses that are designed to detonate the explosive by a slight movement, or impact. Some of them contain poisonous gas. It is usually not the actual explosion of a military device that kills people.
It is usually the shrapnel small pieces of metal from the explosion that kills people. Shrapnel can travel at feet per second in all directions from the explosion.
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