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Flash Blindness
Flash blindness is an either temporary or permanent visual impairment during and following exposure of a varying length of time to a light flash of extremely high intensity, such as a nuclear explosion, flash photograph, lightning strike, or extremely bright light, i.e. a searchlight, laser pointer, landing lights, the sun, or ultraviolet light. The bright light overwhelms the retinas of the eyes and generally gradually fades, lasting anywhere from a few seconds to a few minutes. However, if the eyes are exposed to a high enough level of light, such as a nuclear explosion, the blindness can become permanent. Flash blindness may also occur in everyday life. For example, the subject of a flash photograph can be temporarily flash blinded. This phenomenon is leveraged in non-lethal weapons such as flash grenades and laser dazzlers. Cause Flash blindness is caused by bleaching (oversaturation) of the retinal pigment. As the pigment returns to normal, so too does sight. In daylight t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Visual Impairment
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception. In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. The terms ''low vision'' and ''blindness'' are often used for levels of impairment which are difficult or impossible to correct and significantly impact daily life. In addition to the various permanent conditions, fleeting temporary vision impairment, amaurosis fugax, may occur, and may indicate serious medical problems. The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%). Refractive errors include near-sightedness, far-sightedness, presbyopia, and astigmatism (eye), astigmatism. Cataracts are the most common cause of blindness. Other disorders that may cause visual problems include age-related macular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Defense
The United States Department of Defense (DoD, USDOD, or DOD) is an United States federal executive departments, executive department of the federal government of the United States, U.S. federal government charged with coordinating and supervising the six U.S. armed services: the United States Army, Army, United States Navy, Navy, United States Marine Corps, Marines, United States Air Force, Air Force, United States Space Force, Space Force, the United States Coast Guard, Coast Guard for some purposes, and related functions and agencies. As of November 2022, the department has over 1.4 million active-duty uniformed personnel in the six armed services. It also supervises over 778,000 National Guard (United States), National Guard and reservist personnel, and over 747,000 civilians, bringing the total to over 2.91 million employees. Headquartered at the Pentagon in Arlington County, Virginia, just outside Washington, D.C., the Department of Defense's stated mission is "to provid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Welding
Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Common alternative methods include solvent welding (of thermoplastics) using chemicals to melt materials being bonded without heat, and #Solid-state welding, solid-state welding processes which bond without melting, such as pressure, cold welding, and diffusion bonding. Metal welding is distinct from lower temperature bonding techniques such as brazing and soldering, which do not melt the base metal (parent metal) and instead require flowing a filler metal to solidify their bonds. In addition to melting the base metal in welding, a filler material is typically added to the joint to form a pool of molten material (the weld pool) that cools to form a joint that can be stronger than the base material. Welding also requires a form of shield to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psychological Pain
Psychological pain, mental pain, or emotional pain is an unpleasant feeling (a suffering) of a psychological, mental origin. A pioneer in the field of suicidology, Edwin S. Shneidman, described it as "how much you hurt as a human being. It is mental suffering; mental torment." There are numerous ways psychological pain is referred to, using a different word usually reflects an emphasis on a particular aspect of mind life. Technical terms include algopsychalia and psychalgia, but it may also be called mental pain, emotional pain, psychic pain, social pain, spiritual or soul pain, or suffering. While these clearly are not equivalent terms, one systematic comparison of theories and models of psychological pain, psychic pain, emotional pain, and suffering concluded that each describe the same profoundly unpleasant feeling. Psychological pain is widely believed to be an inescapable aspect of human existence. Other descriptions of psychological pain are "a wide range of subjective ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
The cornea is the transparency (optics), transparent front part of the eyeball which covers the Iris (anatomy), iris, pupil, and Anterior chamber of eyeball, anterior chamber. Along with the anterior chamber and Lens (anatomy), lens, the cornea Refraction, refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK. While the cornea contributes most of the eye's focusing power, its Focus (optics), focus is fixed. Accommodation (eye), Accommodation (the refocusing of light to better view near objects) is accomplished by changing the geometry of the lens. Medical terms related to the cornea often start with the prefix "''wikt:kerat-, kerat-''" from the Ancient Greek, Greek word κέρας, ''horn''. Structure The cornea has myelinated, unmyelinated nerve endings sensitive to touch, temperature and chemicals; a to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nociceptor
A nociceptor (; ) is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain to direct attention to the body part, so the threat can be mitigated; this process is called nociception. Terminology Nociception and pain are usually evoked only by pressures and temperatures that are potentially damaging to tissues. This barrier or threshold of pain, threshold contrasts with the more sensitive visual, auditory, olfactory, taste, and somatosensory responses to stimuli. The experience of pain is individualistic and can be suppressed by stress or exacerbated by anticipation. Simple activation of a nociceptor does not always lead to perceived pain, because the latter also depends on the frequency of the action potentials, integration of pre- and postsynaptic signals, and influences from higher or central processes. Scientific investigation Nociceptors were disc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photic Retinopathy
Photic retinopathy is damage to the eye's retina, particularly the macula, from prolonged exposure to solar radiation or other bright light, e.g., lasers or arc welders. The term includes solar, laser, and welder's retinopathy and is synonymous with retinal phototoxicity.Mainster, Martin A; Turner, Patricia L. (2006). "Retinal Injuries from Light: Mechanisms, Hazards, and Prevention". ''Retina'' (4 ed.). Elsevier Mosby. pp. 1857-70. It usually occurs due to staring at the Sun, watching a solar eclipse, or viewing an ultraviolet, Illuminant D65, or other bright light. /sup> Signs and symptoms * Long-term reduced eyesightSefic-Kasumovic S, Firdus H, Alimanovic E, Ljaljevic S, Sefic M. " ye injuries caused by an eclipse of the sun" ''Med Arh.'' 2000;54(1):41-4. Kallmark FP, Ygge J. "Photo-induced foveal injury after viewing a solar eclipse." ''Acta Ophthalmol Scand.'' 2005 Oct;83(5):586-9. * Central or paracentral scotoma Vision loss due to solar retinopathy is typically revers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operation Tumbler-Snapper
Operation or Operations may refer to: Arts, entertainment and media * ''Operation'' (game), a battery-operated board game that challenges dexterity * Operation (music), a term used in musical set theory * ''Operations'' (magazine), Multi-Man Publishing's house organ for articles and discussion about its wargaming products * ''The Operation'' (film), a 1973 British television film * ''The Operation'' (1990), a crime, drama, TV movie starring Joe Penny, Lisa Hartman, and Jason Beghe * The Operation M.D., formerly The Operation, a Canadian garage rock band * "Operation", a song by Relient K from ''The Creepy EP'', 2001 Television Episodes * "The Operation", ''Sky Dancers'' episode 27 (1996) * "The Operation", ''The Golden Girls'' season 1, episode 18 (1986) * "The Operation", ''You're Only Young Twice'' (1997) series 2, episode 8 (1978) Shows * ''The Operation'' (1992–1998), a reality television series from TLC Business * Manufacturing operations, operation of a facil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effects Of Nuclear Explosions
The effects of a nuclear explosion on its immediate vicinity are typically much more destructive and multifaceted than those caused by conventional explosives. In most cases, the energy released from a nuclear weapon detonated within the troposphere, lower atmosphere can be approximately divided into four basic categories: *the Blast wave, blast and shock wave: 50% of total energy *thermal radiation: 35% of total energy *ionizing radiation: 5% of total energy (more in a neutron bomb) *Nuclear fallout, residual radiation: 5–10% of total energy with the mass of the explosion. Depending on the design of the weapon and the location in which it is detonated, the energy distributed to any one of these categories may be significantly higher or lower. The physical blast effect is created by the coupling of immense amounts of energy, spanning the electromagnetic spectrum, with the surroundings. The environment of the explosion (e.g. submarine, ground burst, air burst, or exo-atmospheric ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nuclear Weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter. Nuclear bombs have had yields between 10 tons (the W54) and 50 megatons for the Tsar Bomba (see TNT equivalent). Yields in the low kilotons can devastate cities. A thermonuclear weapon weighing as little as can release energy equal to more than 1.2 megatons of TNT (5.0 PJ). Apart from the blast, effects of nuclear weapons include firestorms, extreme heat and ionizing radiation, radioactive nuclear fallout, an electromagnetic pulse, and a radar blackout. The first nuclear weapons were developed by the Allied Manhattan Project during World War II. Their production continues to require a large scientific and industrial complex, pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Final Approach (aeronautics)
In aeronautics, the final approach (also called the final leg and final approach leg) is the last leg in an aircraft's approach to landing, when the aircraft is lined up with the runway and descending for landing.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 213 and 241. Aviation Supplies & Academics, 1997. In aviation radio terminology, it is often shortened to "final". The last section of the final approach is sometimes referred to as short final. In a standard airport landing pattern, which is usually used under visual meteorological conditions (VMC), aircraft turns from base leg to final within one-half to two miles of the airport. For instrument approaches, as well as approaches into a controlled airfield under visual flight rules (VFR), often a "straight-in" final approach is used, where all the other legs are dispensed within. Straight-in approaches are discouraged at non-towered airports in the United States. Approach slope An approach slo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Searchlights
A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direction. It is usually constructed so that it can be swiveled about. The most common element used in modern searchlights is Xenon (Xe). However, Rare-earth elements such as lanthanum (La) and cerium (Ce) are used in phosphors to improve light quality in some specialized searchlights. Military use The first use of searchlights using carbon arc technology occurred during the Siege of Paris during the Franco-Prussian War. The Royal Navy used searchlights in 1882 to dazzle and prevent Egyptian forces from manning artillery batteries at Alexandria. Later that same year, the French and British forces landed troops under searchlights. By 1907 the value of searchlights had become widely recognized. One recent use was to assist attacks by t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
