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Visual system
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Structure
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Optic chiasm The optic nerves from both eyes meet and cross at the optic chiasm, at the base of the hypothalamus of the brain. At this point, the information coming from both eyes is combined and then splits according to the visual field. The corresponding halves of the field of view (right and left) are sent to the left and right halves of the brain, respectively, to be processed. That is, the right side of primary visual cortex deals with the left half of the field of view from both eyes, and similarly for the left brain. A small region in the center of the field of view is processed redundantly by both halves of the brain.
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Visual system
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Structure
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Optic tract Information from the right visual field (now on the left side of the brain) travels in the left optic tract. Information from the left visual field travels in the right optic tract. Each optic tract terminates in the lateral geniculate nucleus (LGN) in the thalamus.
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Visual system
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Structure
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Lateral geniculate nucleus The lateral geniculate nucleus (LGN) is a sensory relay nucleus in the thalamus of the brain. The LGN consists of six layers in humans and other primates starting from catarrhines, including cercopithecidae and apes. Layers 1, 4, and 6 correspond to information from the contralateral (crossed) fibers of the nasal retina (temporal visual field); layers 2, 3, and 5 correspond to information from the ipsilateral (uncrossed) fibers of the temporal retina (nasal visual field). Layer one contains M cells, which correspond to the M (magnocellular) cells of the optic nerve of the opposite eye and are concerned with depth or motion. Layers four and six of the LGN also connect to the opposite eye, but to the P cells (color and edges) of the optic nerve. By contrast, layers two, three and five of the LGN connect to the M cells and P (parvocellular) cells of the optic nerve for the same side of the brain as its respective LGN. Spread out, the six layers of the LGN are the area of a credit card and about three times its thickness. The LGN is rolled up into two ellipsoids about the size and shape of two small birds' eggs. In between the six layers are smaller cells that receive information from the K cells (color) in the retina. The neurons of the LGN then relay the visual image to the primary visual cortex (V1) which is located at the back of the brain (posterior end) in the occipital lobe in and close to the calcarine sulcus. The LGN is not just a simple relay station, but it is also a center for processing; it receives reciprocal input from the cortical and subcortical layers and reciprocal innervation from the visual cortex.
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Visual system
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Structure
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Optic radiation The optic radiations, one on each side of the brain, carry information from the thalamic lateral geniculate nucleus to layer 4 of the visual cortex. The P layer neurons of the LGN relay to V1 layer 4C β. The M layer neurons relay to V1 layer 4C α. The K layer neurons in the LGN relay to large neurons called blobs in layers 2 and 3 of V1.There is a direct correspondence from an angular position in the visual field of the eye, all the way through the optic tract to a nerve position in V1 (up to V4, i.e. the primary visual areas. After that, the visual pathway is roughly separated into a ventral and dorsal pathway).
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Visual system
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Structure
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Visual cortex The visual cortex is the largest system in the human brain and is responsible for processing the visual image. It lies at the rear of the brain (highlighted in the image), above the cerebellum. The region that receives information directly from the LGN is called the primary visual cortex, (also called V1 and striate cortex). It creates a bottom-up saliency map of the visual field to guide attention or eye gaze to salient visual locations, hence selection of visual input information by attention starts at V1 along the visual pathway. Visual information then flows through a cortical hierarchy. These areas include V2, V3, V4 and area V5/MT (the exact connectivity depends on the species of the animal). These secondary visual areas (collectively termed the extrastriate visual cortex) process a wide variety of visual primitives. Neurons in V1 and V2 respond selectively to bars of specific orientations, or combinations of bars. These are believed to support edge and corner detection. Similarly, basic information about color and motion is processed here.Heider, et al. (2002) have found that neurons involving V1, V2, and V3 can detect stereoscopic illusory contours; they found that stereoscopic stimuli subtending up to 8° can activate these neurons.
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Visual system
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Structure
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Visual association cortex As visual information passes forward through the visual hierarchy, the complexity of the neural representations increases. Whereas a V1 neuron may respond selectively to a line segment of a particular orientation in a particular retinotopic location, neurons in the lateral occipital complex respond selectively to complete object (e.g., a figure drawing), and neurons in visual association cortex may respond selectively to human faces, or to a particular object.
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Visual system
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Structure
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Along with this increasing complexity of neural representation may come a level of specialization of processing into two distinct pathways: the dorsal stream and the ventral stream (the Two Streams hypothesis, first proposed by Ungerleider and Mishkin in 1982). The dorsal stream, commonly referred to as the "where" stream, is involved in spatial attention (covert and overt), and communicates with regions that control eye movements and hand movements. More recently, this area has been called the "how" stream to emphasize its role in guiding behaviors to spatial locations. The ventral stream, commonly referred to as the "what" stream, is involved in the recognition, identification and categorization of visual stimuli.
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Visual system
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Structure
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However, there is still much debate about the degree of specialization within these two pathways, since they are in fact heavily interconnected.Horace Barlow proposed the efficient coding hypothesis in 1961 as a theoretical model of sensory coding in the brain. Limitations in the applicability of this theory in the primary visual cortex (V1) motivated the V1 Saliency Hypothesis that V1 creates a bottom-up saliency map to guide attention exogenously. With attentional selection as a center stage, vision is seen as composed of encoding, selection, and decoding stages.The default mode network is a network of brain regions that are active when an individual is awake and at rest. The visual system's default mode can be monitored during resting state fMRI: Fox, et al. (2005) have found that "The human brain is intrinsically organized into dynamic, anticorrelated functional networks'", in which the visual system switches from resting state to attention.
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Visual system
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Structure
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In the parietal lobe, the lateral and ventral intraparietal cortex are involved in visual attention and saccadic eye movements. These regions are in the Intraparietal sulcus (marked in red in the adjacent image).
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Visual system
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Development
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Infancy Newborn infants have limited color perception. One study found that 74% of newborns can distinguish red, 36% green, 25% yellow, and 14% blue. After one month, performance "improved somewhat." Infant's eyes do not have the ability to accommodate. The pediatricians are able to perform non-verbal testing to assess visual acuity of a newborn, detect nearsightedness and astigmatism, and evaluate the eye teaming and alignment. Visual acuity improves from about 20/400 at birth to approximately 20/25 at 6 months of age. All this is happening because the nerve cells in their retina and brain that control vision are not fully developed.
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Visual system
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Development
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Childhood and adolescence Depth perception, focus, tracking and other aspects of vision continue to develop throughout early and middle childhood. From recent studies in the United States and Australia there is some evidence that the amount of time school aged children spend outdoors, in natural light, may have some impact on whether they develop myopia. The condition tends to get somewhat worse through childhood and adolescence, but stabilizes in adulthood. More prominent myopia (nearsightedness) and astigmatism are thought to be inherited. Children with this condition may need to wear glasses.
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Visual system
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Development
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Adulthood Eyesight is often one of the first senses affected by aging. A number of changes occur with aging: Over time, the lens become yellowed and may eventually become brown, a condition known as brunescence or brunescent cataract. Although many factors contribute to yellowing, lifetime exposure to ultraviolet light and aging are two main causes.
The lens becomes less flexible, diminishing the ability to accommodate (presbyopia).
While a healthy adult pupil typically has a size range of 2–8 mm, with age the range gets smaller, trending towards a moderately small diameter.
On average tear production declines with age. However, there are a number of age-related conditions that can cause excessive tearing.
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Visual system
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Other functions
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Balance Along with proprioception and vestibular function, the visual system plays an important role in the ability of an individual to control balance and maintain an upright posture. When these three conditions are isolated and balance is tested, it has been found that vision is the most significant contributor to balance, playing a bigger role than either of the two other intrinsic mechanisms. The clarity with which an individual can see his environment, as well as the size of the visual field, the susceptibility of the individual to light and glare, and poor depth perception play important roles in providing a feedback loop to the brain on the body's movement through the environment. Anything that affects any of these variables can have a negative effect on balance and maintaining posture. This effect has been seen in research involving elderly subjects when compared to young controls, in glaucoma patients compared to age matched controls, cataract patients pre and post surgery, and even something as simple as wearing safety goggles. Monocular vision (one eyed vision) has also been shown to negatively impact balance, which was seen in the previously referenced cataract and glaucoma studies, as well as in healthy children and adults.According to Pollock et al. (2010) stroke is the main cause of specific visual impairment, most frequently visual field loss (homonymous hemianopia, a visual field defect). Nevertheless, evidence for the efficacy of cost-effective interventions aimed at these visual field defects is still inconsistent.
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Visual system
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Clinical significance
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Proper function of the visual system is required for sensing, processing, and understanding the surrounding environment. Difficulty in sensing, processing and understanding light input has the potential to adversely impact an individual's ability to communicate, learn and effectively complete routine tasks on a daily basis.
In children, early diagnosis and treatment of impaired visual system function is an important factor in ensuring that key social, academic and speech/language developmental milestones are met.
Cataract is clouding of the lens, which in turn affects vision. Although it may be accompanied by yellowing, clouding and yellowing can occur separately. This is typically a result of ageing, disease, or drug use.
Presbyopia is a visual condition that causes farsightedness. The eye's lens becomes too inflexible to accommodate to normal reading distance, focus tending to remain fixed at long distance.
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Visual system
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Clinical significance
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Glaucoma is a type of blindness that begins at the edge of the visual field and progresses inward. It may result in tunnel vision. This typically involves the outer layers of the optic nerve, sometimes as a result of buildup of fluid and excessive pressure in the eye.Scotoma is a type of blindness that produces a small blind spot in the visual field typically caused by injury in the primary visual cortex.
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Visual system
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Clinical significance
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Homonymous hemianopia is a type of blindness that destroys one entire side of the visual field typically caused by injury in the primary visual cortex.
Quadrantanopia is a type of blindness that destroys only a part of the visual field typically caused by partial injury in the primary visual cortex. This is very similar to homonymous hemianopia, but to a lesser degree.
Prosopagnosia, or face blindness, is a brain disorder that produces an inability to recognize faces. This disorder often arises after damage to the fusiform face area.
Visual agnosia, or visual-form agnosia, is a brain disorder that produces an inability to recognize objects. This disorder often arises after damage to the ventral stream.
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Visual system
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Other animals
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Different species are able to see different parts of the light spectrum; for example, bees can see into the ultraviolet, while pit vipers can accurately target prey with their pit organs, which are sensitive to infrared radiation. The mantis shrimp possesses arguably the most complex visual system of any species. The eye of the mantis shrimp holds 16 color receptive cones, whereas humans only have three. The variety of cones enables them to perceive an enhanced array of colors as a mechanism for mate selection, avoidance of predators, and detection of prey. Swordfish also possess an impressive visual system. The eye of a swordfish can generate heat to better cope with detecting their prey at depths of 2000 feet. Certain one-celled microorganisms, the warnowiid dinoflagellates have eye-like ocelloids, with analogous structures for the lens and retina of the multi-cellular eye. The armored shell of the chiton Acanthopleura granulata is also covered with hundreds of aragonite crystalline eyes, named ocelli, which can form images.Many fan worms, such as Acromegalomma interruptum which live in tubes on the sea floor of the Great Barrier Reef, have evolved compound eyes on their tentacles, which they use to detect encroaching movement. If movement is detected, the fan worms will rapidly withdraw their tentacles. Bok, et al., have discovered opsins and G proteins in the fan worm's eyes, which were previously only seen in simple ciliary photoreceptors in the brains of some invertebrates, as opposed to the rhabdomeric receptors in the eyes of most invertebrates.Only higher primate Old World (African) monkeys and apes (macaques, apes, orangutans) have the same kind of three-cone photoreceptor color vision humans have, while lower primate New World (South American) monkeys (spider monkeys, squirrel monkeys, cebus monkeys) have a two-cone photoreceptor kind of color vision.
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Visual system
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History
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In the second half of the 19th century, many motifs of the nervous system were identified such as the neuron doctrine and brain localization, which related to the neuron being the basic unit of the nervous system and functional localisation in the brain, respectively. These would become tenets of the fledgling neuroscience and would support further understanding of the visual system.
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Visual system
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History
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The notion that the cerebral cortex is divided into functionally distinct cortices now known to be responsible for capacities such as touch (somatosensory cortex), movement (motor cortex), and vision (visual cortex), was first proposed by Franz Joseph Gall in 1810. Evidence for functionally distinct areas of the brain (and, specifically, of the cerebral cortex) mounted throughout the 19th century with discoveries by Paul Broca of the language center (1861), and Gustav Fritsch and Eduard Hitzig of the motor cortex (1871). Based on selective damage to parts of the brain and the functional effects of the resulting lesions, David Ferrier proposed that visual function was localized to the parietal lobe of the brain in 1876. In 1881, Hermann Munk more accurately located vision in the occipital lobe, where the primary visual cortex is now known to be.In 2014, a textbook "Understanding vision: theory, models, and data" illustrates how to link neurobiological data and visual behavior/psychological data through theoretical principles and computational models.
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Twiddler's syndrome
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Twiddler's syndrome
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Twiddler's syndrome is a malfunction of a pacemaker due to manipulation of the device and the consequent dislodging of the leads from their intended location. As the leads move, they stop pacing the heart and can cause strange symptoms such as phrenic nerve stimulation resulting in abdominal pulsing or brachial plexus stimulation resulting in rhythmic arm twitching. Twiddler's syndrome in patients with an implanted defibrilator may lead to inadequate, painful defibrillation-shocks.
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4-HO-DSBT
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4-HO-DSBT
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4-HO-DsBT (4-hydroxy-N,N-di-sec-butyltryptamine) is a tryptamine derivative which acts as a serotonin receptor agonist. It was first made by Alexander Shulgin and is mentioned in his book TiHKAL, but was never tested by him. However it has subsequently been tested in vitro and unlike the n-butyl and isobutyl isomers which are much weaker, the s-butyl derivative retains reasonable potency, with a similar 5-HT2A receptor affinity to MiPT but better selectivity over the 5-HT1A and 5-HT2B subtypes.
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Thorium(IV) hydroxide
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Thorium(IV) hydroxide
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Thorium(IV) hydroxide is an inorganic compound with a chemical formula Th(OH)4.
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Thorium(IV) hydroxide
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Production
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Thorium(IV) hydroxide can be produced by reacting sodium hydroxide and soluble thorium salts.
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Thorium(IV) hydroxide
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Reactions
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New thorium(IV) hydroxide is soluble in acid but its solubility will decrease when older.Thorium(IV) hydroxide will break up at high temperature and produce thorium dioxide: Th(OH)4 → ThO2 + 2 H2OAt high pressure, thorium(IV) hydroxide reacts with carbon dioxide, and produce thorium carbonate hemihydrate.
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4-Isopropenylphenol
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4-Isopropenylphenol
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4-Isopropenylphenol is an organic compound with the formula CH2=(CH3)CC6H4OH. The molecule consists of a 2-propenyl group (CH2=C-CH3) affixed to the 4 position of phenol. The compound is an intermediate in the production of bisphenol A (BPA), 2.7 Mkg/y of which are produced annually (2007). It is also generated by the recycling of o,p-BPA, a byproduct of the production of the p,p-isomer of BPA.
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4-Isopropenylphenol
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Synthesis and reactions
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The high-temperature hydrolysis of BPA gives the title compound together with phenol: (CH3)2C(C6H4OH)2 + H2O → CH2=(CH3)CC6H4OH + C6H5OHThe compound can also be produced by catalytic dehydrogenation of 4-isopropylphenol.4-Isopropenylphenol undergoes O-protonation by sulfuric acid, giving the carbocation, which undergoes a variety of dimerization reactions.
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Recoilless rifle
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Recoilless rifle
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A recoilless rifle (rifled), recoilless launcher (smoothbore), or simply recoilless gun, sometimes abbreviated to "RR" or "RCL" (for ReCoilLess) is a type of lightweight artillery system or man-portable launcher that is designed to eject some form of countermass such as propellant gas from the rear of the weapon at the moment of firing, creating forward thrust that counteracts most of the weapon's recoil. This allows for the elimination of much of the heavy and bulky recoil-counteracting equipment of a conventional cannon as well as a thinner-walled barrel, and thus the launch of a relatively large projectile from a platform that would not be capable of handling the weight or recoil of a conventional gun of the same size. Technically, only devices that use spin-stabilized projectiles fired from a rifled barrel are recoilless rifles, while smoothbore variants (which can be fin-stabilized or unstabilized) are recoilless guns. This distinction is often lost, and both are often called recoilless rifles.Though similar in appearance to a tube-based rocket launcher (since these also operate on a recoilless launch principle), the key difference is that recoilless weapons fire shells using a conventional smokeless propellant. While there are rocket-assisted rounds for recoilless weapons, they are still ejected from the barrel by the deflagration of a conventional propelling charge.
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Recoilless rifle
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Recoilless rifle
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Because some projectile velocity is inevitably lost to the recoil compensation, recoilless rifles tend to have inferior range to traditional cannon, although with a far greater ease of transport, making them popular with paratroop, mountain warfare and special forces units, where portability is of particular concern, as well as with some light infantry and infantry fire support units. The greatly diminished recoil allows for devices that can be carried by individual infantrymen: heavier recoilless rifles are mounted on light tripods, wheeled light carriages, or small vehicles, and intended to be carried by crew of two to five. The largest versions retain enough bulk and recoil to be restricted to a towed mount or relatively heavy vehicle, but are still much lighter and more portable than cannon of the same scale. Such large systems have been replaced by guided anti-tank missiles in many armies.
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Recoilless rifle
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Design
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There are a number of principles under which a recoilless gun can operate, all involving the ejection of some kind of counter-mass from the rear of the gun tube to offset the force of the projectile being fired forward. The most basic method, and the first to be employed, is simply making a double-ended gun with a conventional sealed breech, which fires identical projectiles forwards and backwards. Such a system places enormous stress on its midpoint, is extremely cumbersome to reload, and has the highly undesirable effect of launching a projectile potentially just as deadly as the one launched at the enemy at a point behind the shooter where their allies may well be.
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Recoilless rifle
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Design
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The most common system involves venting some portion of the weapon's propellant gas to the rear of the tube, in the same fashion as a rocket launcher. This creates a forward directed momentum which is nearly equal to the rearward momentum (recoil) imparted to the system by accelerating the projectile. The balance thus created does not leave much momentum to be imparted to the weapon's mounting or the gunner in the form of felt recoil. Since recoil has been mostly negated, a heavy and complex recoil damping mechanism is not necessary. Despite the name, it is rare for the forces to completely balance, and real-world recoilless rifles do recoil noticeably (with varying degrees of severity). Recoilless rifles will not function correctly if the venting system is damaged, blocked, or poorly maintained: in this state, the recoil-damping effect can be reduced or lost altogether, leading to dangerously powerful recoil. Conversely, if a projectile becomes lodged in the barrel for any reason, the entire weapon will be forced forward.
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Recoilless rifle
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Design
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Recoilless rifle rounds for breech-loading reloadable systems resemble conventional cased ammunition, using a driving band to engage the rifled gun tube and spin-stabilize the projectile. The casing of a recoilless rifle round is often perforated to vent the propellant gases, which are then directed to the rear by an expansion chamber surrounding the weapon's breech. In the case of single-shot recoilless weapons such as the Panzerfaust or AT4, the device is externally almost identical in design to a single-shot rocket launcher: the key difference is that the launch tube is a gun that launches the projectile using a pre-loaded powder charge, not a hollow tube. Weapons of this type can either encase their projectile inside the disposable gun tube, or mount it on the muzzle: the latter allows the launching of an above-caliber projectile. Like single shot rocket launchers, the need to only survive a single firing means that single-shot recoilless weapons can be made from relatively flimsy and therefore very light materials, such as fiberglass. Recoilless gun launch systems are often used to provide the initial thrust for man-portable weapons firing rocket-powered projectiles: examples include the RPG-7, Panzerfaust 3 and MATADOR.
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Recoilless rifle
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Design
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Since venting propellant gases to the rear can be dangerous in confined spaces, some recoilless guns use a combination of a countershot and captive piston propelling cartridge design to avoid both recoil and backblast. The Armbrust "cartridge," for example, contains the propellant charge inside a double-ended piston assembly, with the projectile in front, and an equal countermass of shredded plastic to the rear. On firing, the propellant expands rapidly, pushing the pistons outward. This pushes the projectile forwards towards the target and the countermass backwards providing the recoilless effect. The shredded plastic countermass is quickly slowed by air resistance and is harmless at a distance more than a few feet from the rear of the barrel. The two ends of the piston assembly are captured at the ends of the barrel, by which point the propellant gas has expanded and cooled enough that there is no threat of explosion. Other countermass materials that have been used include inert powders and liquids.
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Recoilless rifle
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History
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The earliest known example of a design for a gun based on recoilless principles was created by Leonardo da Vinci in the 15th or early 16th century. This design was of a gun which fired projectiles in opposite directions, but there is no evidence any physical firearm based on the design was constructed at the time.
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Recoilless rifle
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History
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In 1879 a French patent was filed by Alfred Krupp for a recoilless gun.The first recoilless gun known to have actually been constructed was developed by Commander Cleland Davis of the US Navy, just prior to World War I. His design, named the Davis gun, connected two guns back-to-back, with the backwards-facing gun loaded with lead balls and grease of the same weight as the shell in the other gun. His idea was used experimentally by the British as an anti-Zeppelin and anti-submarine weapon mounted on a Handley Page O/100 bomber and intended to be installed on other aircraft.In the Soviet Union, the development of recoilless weapons ("Dinamo-Reaktivnaya Pushka" (DRP), roughly "dynamic reaction cannon") began in 1923. In the 1930s, many different types of weapons were built and tested with configurations ranging from 37 mm to 305 mm. Some of the smaller examples were tested in aircraft (Grigorovich I-Z and Tupolev I-12) and saw some limited production and service, but development was abandoned around 1938. The best-known of these early recoilless rifles was the Model 1935 76 mm DRP designed by Leonid Kurchevsky. A small number of these mounted on trucks saw combat in the Winter War. Two were captured by the Finns and tested; one example was given to the Germans in 1940.
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Recoilless rifle
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History
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The first recoilless gun to enter service in Germany was the 7.5 cm Leichtgeschütz 40 ("light gun" '40), a simple 75 mm smoothbore recoilless gun developed to give German airborne troops artillery and anti-tank support that could be parachuted into battle. The 7.5cm LG 40 was found to be so useful during the invasion of Crete that Krupp and Rheinmetall set to work creating more powerful versions, respectively the 10.5 cm Leichtgeschütz 40 and 10.5 cm Leichtgeschütz 42. These weapons were loosely copied by the US Army. The Luftwaffe also showed great interest in aircraft-mounted recoilless weapons to allow their planes to attack tanks, fortified structures and ships. These included the unusual Düsenkanone 88, an 88mm recoilless rifle fed by a 10-round rotary cylinder and with the exhaust vent angled upwards at 51 degrees to the barrel so it could pass through the host aircraft's fuselage rather than risking a rear-vented backblast damaging the tail, and the Sondergerät SG104 "Münchhausen", a gargantuan 14-inch (355.6mm) weapon designed to be mounted under the fuselage of a Dornier Do 217. None of these systems proceeded beyond the prototype stage.The US did have a development program, and it is not clear to what extent the German designs were copied. These weapons remained fairly rare during the war, although the American M20 became increasingly common in 1945. Postwar saw a great deal of interest in recoilless systems, as they potentially offered an effective replacement for the obsolete anti-tank rifle in infantry units.
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Recoilless rifle
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History
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During World War II, the Swedish military developed a shoulder-fired 20 mm device, the Pansarvärnsgevär m/42 (20 mm m/42); the British expressed their interest in it, but by that point the weapon, patterned after obsolete anti-tank rifles, was too weak to be effective against period tank armor. This system would form the basis of the much more successful Carl Gustav recoilless rifle postwar.
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Recoilless rifle
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History
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By the time of the Korean War, recoilless rifles were found throughout the US forces. The earliest American infantry recoilless rifles were the shoulder-fired 57 mm M18 and the tripod-mounted 75 mm M20, later followed by the 105 mm M27: the latter proved unreliable, too heavy, and too hard to aim. Newer models replacing these were the 90 mm M67 and 106 mm M40 (which was actually 105 mm caliber, but designated otherwise to prevent accidental issue of incompatible M27 ammunition). In addition, the Davy Crockett, a muzzle-loaded recoilless launch system for tactical nuclear warheads intended to counteract Soviet tank units, was developed in the 1960s and deployed to American units in Germany.
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Recoilless rifle
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History
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The Soviet Union adopted a series of crew-served smoothbore recoilless guns in the 1950s and 1960s, specifically the 73mm SPG-9, 82mm B-10 and 107mm B-11. All are found quite commonly around the world in the inventories of former Soviet client states, where they are usually used as anti-tank guns.
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Recoilless rifle
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History
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The British, whose efforts were led by Charles Dennistoun Burney, inventor of the Wallbuster HESH round, also developed recoilless designs. Burney demonstrated the technique with a recoilless 4-gauge shotgun. His "Burney Gun" was developed to fire the Wallbuster shell against the Atlantic Wall defences, but was not required in the D-Day landings of 1944. He went on to produce further designs, with two in particular created as anti-tank weapons. The Ordnance, RCL, 3.45 in could be fired off a man's shoulder or from a light tripod, and fired an 11 lb (5 kg) wallbuster shell to 1,000 yards. The larger Ordnance RCL. 3.7in fired a 22.2 lb (10 kg) wallbuster to 2,000 yards. Postwar work developed and deployed the BAT (Battalion, Anti Tank) series of recoilless rifles, culminating in the 120 mm L6 WOMBAT. This was too large to be transported by infantry and was usually towed by jeep. The weapon was aimed via a spotting rifle, a modified Bren Gun on the MOBAT and an American M8C spotting rifle on the WOMBAT: the latter fired a .50 BAT (12.7x77mm) point-detonating incendiary tracer round whose trajectory matched that of the main weapon. When tracer rounds hits were observed, the main gun was fired.
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Recoilless rifle
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History
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During the late 1960s and 1970s, SACLOS wire-guided missiles began to supplant recoilless rifles in the anti-tank role. While recoilless rifles retain several advantages such as being able to be employed at extremely close range, as a guided missile typically has a significant deadzone before it can arm and begin to seek its target, missile systems tend to be lighter and more accurate, and are better suited to deployment of hollow-charge warheads. The large crew-served recoilless rifle started to disappear from first-rate armed forces, except in areas such as the Arctic, where thermal batteries used to provide after-launch power to wire-guided missiles like M47 Dragon and BGM-71 TOW would fail due to extremely low temperatures. The former 6th Light Infantry Division in Alaska used the M67 in its special weapons platoons, as did the Ranger Battalions and the US Army's Berlin Brigade. The last major use was the M50 Ontos, which mounted six M40 rifles on a light (9 ton) tracked chassis. They were largely used in an anti-personnel role firing "beehive" flechette rounds. In 1970 the Ontos was removed from service and most were broken up. The M40, usually mounted on a jeep or technical, is still very common in conflict zones throughout the world, where it is used as a hard-hitting strike weapon in support of infantry, with the M40-armed technical fulfilling a similar combat role to an attack helicopter.
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Recoilless rifle
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History
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Front-line recoilless weapons in the armies of modern industrialized nations are mostly man-portable devices such as the Carl Gustav, an 84 mm weapon. First introduced in 1948 and exported extensively since 1964, it is still in widespread use throughout the world today: a huge selection of special-purpose rounds are available for the system, and the current variant, known as the M4 or M3E1, is designed to be compatible with computerized optics and future "smart" ammunition. Many nations also use a weapon derived from the Carl Gustav, the one-shot AT4, which was originally developed in 1984 to fulfil an urgent requirement for an effective replacement for the M72 LAW after the failure of the FGR-17 Viper program the previous year. The ubiquitous RPG-7 is also technically a recoilless gun, since its rocket-powered projectile is launched using an explosive booster charge (even more so when firing the OG-7V anti-personnel round, which has no rocket motor), though it is usually not classified as one.
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Recoilless rifle
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Civilian use
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Obsolete 75mm M20 and 105mm M27 recoilless rifles were used by the U.S. National Park Service and the U.S. Forest Service as a system for triggering controlled avalanches at a safe distance, from the early 1950s until the US Military's inventory of surplus ammunition for these weapons was exhausted in the 1990s. They were then replaced with M40 106mm recoilless rifles, but following a catastrophic in-bore ammunition explosion that killed one of the five-man gun crew at Alpine Meadows Ski Resort, California, in 1995 and two further in-bore explosions at Mammoth Mountain, California, within thirteen days of each other in December 2002, all such guns were removed from use and replaced with surplus 105mm howitzers.
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Ponazuril
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Ponazuril
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Ponazuril (INN), sold by Merial, Inc., now part of Boehringer Ingelheim, under the trade name Marquis® (15% w/w ponazuril), is a drug currently approved for the treatment of equine protozoal myeloencephalitis (EPM) in horses, caused by coccidia Sarcocystis neurona. More recently, veterinarians have been preparing a formulary version of the medication for use in small animals such as cats, dogs, and rabbits against coccidia as an intestinal parasite. Coccidia treatment in small animals is far shorter than treatment for EPM.
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Electric Image Animation System
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Electric Image Animation System
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The Electric Image Animation System (EIAS) is a 3D computer graphics package published by EIAS3D. It currently runs on the macOS and Windows platforms.
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Electric Image Animation System
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History
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Electric Image, Inc. was initially a visual effects production company. They developed their own in-house 3D animation and rendering package for the Macintosh beginning in the late 1980s, calling it ElectricImage Animation System. (To avoid confusion with the current product with its similar name, we will refer to this initial incarnation of the product simply as ElectricImage.) When the company later decided to offer their software for sale externally, it quickly gained a customer base that lauded the developers for the software's exceptionally fast rendering engine and high image quality. Because it was capable of film-quality output on commodity hardware, ElectricImage was popular in the movie and television industries throughout the decade. It was used by the "Rebel Unit" at Industrial Light and Magic quite extensively and was in use by a variety of game companies, such as Bad Mojo and Bad Day on the Midway. However, only these high end effects companies could afford it: Electric Image initially sold for US $7500.
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Electric Image Animation System
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History
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EIAS has been used in numerous film and television productions, such as: Piranha 3D, Alien Trespass, Pirates of the Caribbean: The Curse of the Black Pearl, Daddy Day Care, K-19: The Widowmaker, Gangs of New York, Austin Powers: Goldmember, Men In Black II, The Bourne Identity, Behind Enemy Lines, Time Machine, Ticker, JAG - Pilot Episode, Spawn, Star Trek: First Contact, Star Trek: Insurrection, Galaxy Quest, Mission to Mars, Austin Powers: The Spy Who Shagged Me, Star Wars Episode 1: The Phantom Menace, Titan A.E., U-571, Dinosaur, Terminator 2: Judgment Day, Terminator 2: Judgment Day - DVD Intro, Jungle Book 2, American President, Sleepers, Star Wars Special Edition, Empire Strikes Back Special Edition, Return of Jedi Special Edition, Bicentennial Man, Vertical Limit, Elf, Blade Trinity, and Lost In Space.
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Electric Image Animation System
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History
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TV Shows: Revolution, Breaking Bad, Alcatraz, Pan AM, The whole Truth, Lost, Flash Forward, Fringe, Surface, Weeds, Pushing Daisies, The X-Files, Alias, Smallville, Star Trek: The Next Generation, Babylon 5, Young Indiana Jones, Star Trek Voyager, Mists of Avalon, Star Trek Enterprise....
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Electric Image Animation System
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History
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Electric Image, Inc. was always a small company that produced software on the Mac platform and so never had a large a market share. Play, Inc. purchased Electric Image corporation in November 1998. The first version of EIAS released under the Play moniker was version 2.9. Play later released the 3.0 version. This was the first version to run on Windows, and to mark this move, Play renamed the package Electric Image Universe. Play was never a greatly successful company, and so Electric Image Universe stagnated during the time they owned it.
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Electric Image Animation System
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History
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In 2000, Dwight Parscale (former CEO of Newtek) and original Electric Image founders Markus Houy and Jay Roth bought back the original company from Play Inc. On September 19, 2000, the company bought back the shares of Electric Image from Play and set about to recapture the product's former customer base. The new company released version 4.0 and 5.0 under the Electric Image moniker. Then due to a licensing problem with Spatial Technologies, they dropped the Modeler program from the version 5.5 release, and renamed the package back to Electric Image Animation System.
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Electric Image Animation System
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History
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Versions 6.0 and 6.5 were subsequently released with vast improvements to the rendering engine and OpenGL performance. Version 6.5r2 added FBX file importing capability. 6.6 added Universal Binary support and finally drops support for Mac OS 9. Version 7.0 brought Multi-Layer Rendering, Image-Based Lighting, Raytrace Sky Maps and Rigid Body Dynamics. The version, 8.0, added Photon Mapping, Fast soft shadows, area light, Quadratic light drop-off, EXR and 16bit image input support, Displacement Sea Level, new Weight maps tools, much workflow enhancement and Renderama improvements.
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Electric Image Animation System
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History
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In 2009, EITG began negotiations to sell the intellectual property rights of ElectricImage. On January 12, 2010 it was announced that Tomas Egger, Igor Yatsenko, and Igor Ivaniuk had become the new owners of EIAS. Known collectively as "The Igors", Igor Yatsenko and Igor Ivaniuk had been EIAS's primary software developers for many years. They released version 9.0 in November 2012, followed by version 9.1 in June 2013.
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Electric Image Animation System
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Market positioning
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The existing customer base for EIAS favors it for its fast renderer, its high output quality, and its camera mapping features. The tool set lends itself particularly well to hard-surface animation/rendering and other forms of non-organic tasks. It is most popular with architects and visual effects artists for TV and film.
EIAS's primary competitors in the integrated 3D package space are Autodesk with Maya, 3D Studio Max and Softimage, Maxon with Cinema 4D, and Newtek with Lightwave 3D.
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Electric Image Animation System
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Components
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The Electric Image Animation System is not a single program, but rather a suite of several programs designed to work together. Each of the primary programs handles a particular part of the production workflow: Animator Animator is the EIAS animation program. It can directly import 3D models in the Lightwave, 3D Studio, AutoCAD, Maya, and Electric Image FACT formats. In addition to animating models, Animator allows you to set up rendering settings. It efficiently supports the animation of very geometrically complex projects.
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Electric Image Animation System
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Components
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Camera Camera is the EIAS rendering program, known for its speed and high image quality. As of version 9.0, it supports ray tracing, Phong shading, scanline rendering, spatial anti-aliasing, motion blur, caustics, radiosity, Photon mapping, Irradiance Cache, Screen Cache and global illumination. Camera outputs to several file formats, like Quicktime and EI's own Image format. The latter is directly supported by Adobe After Effects CC and Adobe Photoshop CC.
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Electric Image Animation System
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Components
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Renderama Renderama and Renderama Slave compose EIAS's distributed network rendering system. It allows for the rendering of a project to be distributed over a network's computers (i.e., for the formation of a render farm). It supports both single and multiprocessor computers, taking advantage of all available processors to distribute the workload. It also supports rendering across platforms (e.g., Windows 7/8 - 64 bits and Mac OS X 10.6.8 or earlier).
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Electric Image Animation System
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Components
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Modeler Modeler saves its files in Electric Image's "FACT" file format for importing into Animator (see above). It supports ACIS modeling, "ÜberNurbs" (EIAS' subdivision surfaces modeling technology), LAWS (based on parametric formulas) as well as Boolean operations and other modern modeling tools.
Modeler last shipped in Electric Image Universe 5.0. As a result, users of EIAS 5.5 and newer use a third-party modeler instead. As of this writing, Electric Image recommends Nevercenter Silo for this purpose. Form•Z from auto•des•sys is also popularly used as a companion for EIAS.
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Gamma camera
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Gamma camera
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A gamma camera (γ-camera), also called a scintillation camera or Anger camera, is a device used to image gamma radiation emitting radioisotopes, a technique known as scintigraphy. The applications of scintigraphy include early drug development and nuclear medical imaging to view and analyse images of the human body or the distribution of medically injected, inhaled, or ingested radionuclides emitting gamma rays.
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Gamma camera
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Imaging techniques
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Scintigraphy ("scint") is the use of gamma cameras to capture emitted radiation from internal radioisotopes to create two-dimensional images.
SPECT (single photon emission computed tomography) imaging, as used in nuclear cardiac stress testing, is performed using gamma cameras. Usually one, two or three detectors or heads, are slowly rotated around the patient's torso.
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Gamma camera
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Imaging techniques
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Multi-headed gamma cameras can also be used for positron emission tomography (PET) scanning, provided that their hardware and software can be configured to detect "coincidences" (near simultaneous events on 2 different heads). Gamma camera PET is markedly inferior to PET imaging with a purpose designed PET scanner, as the scintillator crystal has poor sensitivity for the high-energy annihilation photons, and the detector area is significantly smaller. However, given the low cost of a gamma camera and its additional flexibility compared to a dedicated PET scanner, this technique is useful where the expense and resource implications of a PET scanner cannot be justified.
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Gamma camera
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Construction
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A gamma camera consists of one or more flat crystal planes (or detectors) optically coupled to an array of photomultiplier tubes in an assembly known as a "head", mounted on a gantry. The gantry is connected to a computer system that both controls the operation of the camera and acquires and stores images.: 82 The construction of a gamma camera is sometimes known as a compartmental radiation construction.
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Gamma camera
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Construction
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The system accumulates events, or counts, of gamma photons that are absorbed by the crystal in the camera. Usually a large flat crystal of sodium iodide with thallium doping NaI(Tl) in a light-sealed housing is used. The highly efficient capture method of this combination for detecting gamma rays was discovered in 1944 by Sir Samuel Curran whilst he was working on the Manhattan Project at the University of California at Berkeley. Nobel prize-winning physicist Robert Hofstadter also worked on the technique in 1948.The crystal scintillates in response to incident gamma radiation. When a gamma photon leaves the patient (who has been injected with a radioactive pharmaceutical), it knocks an electron loose from an iodine atom in the crystal, and a faint flash of light is produced when the dislocated electron again finds a minimal energy state. The initial phenomenon of the excited electron is similar to the photoelectric effect and (particularly with gamma rays) the Compton effect. After the flash of light is produced, it is detected. Photomultiplier tubes (PMTs) behind the crystal detect the fluorescent flashes (events) and a computer sums the counts. The computer reconstructs and displays a two dimensional image of the relative spatial count density on a monitor. This reconstructed image reflects the distribution and relative concentration of radioactive tracer elements present in the organs and tissues imaged.: 162
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Gamma camera
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Signal processing
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Hal Anger developed the first gamma camera in 1957. His original design, frequently called the Anger camera, is still widely used today. The Anger camera uses sets of vacuum tube photomultipliers (PMT). Generally each tube has an exposed face of about 7.6 cm in diameter and the tubes are arranged in hexagon configurations, behind the absorbing crystal. The electronic circuit connecting the photodetectors is wired so as to reflect the relative coincidence of light fluorescence as sensed by the members of the hexagon detector array. All the PMTs simultaneously detect the (presumed) same flash of light to varying degrees, depending on their position from the actual individual event. Thus the spatial location of each single flash of fluorescence is reflected as a pattern of voltages within the interconnecting circuit array.
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Gamma camera
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Signal processing
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The location of the interaction between the gamma ray and the crystal can be determined by processing the voltage signals from the photomultipliers; in simple terms, the location can be found by weighting the position of each photomultiplier tube by the strength of its signal, and then calculating a mean position from the weighted positions.: 112 The total sum of the voltages from each photomultiplier, measured by a pulse height analyzer is proportional to the energy of the gamma ray interaction, thus allowing discrimination between different isotopes or between scattered and direct photons.: 166
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Gamma camera
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Spatial resolution
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In order to obtain spatial information about the gamma-ray emissions from an imaging subject (e.g. a person's heart muscle cells which have absorbed an intravenous injected radioactive, usually thallium-201 or technetium-99m, medicinal imaging agent) a method of correlating the detected photons with their point of origin is required.
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Gamma camera
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Spatial resolution
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The conventional method is to place a collimator over the detection crystal/PMT array. The collimator consists of a thick sheet of lead, typically 25 to 55 millimetres (1 to 2.2 in) thick, with thousands of adjacent holes through it. There are three types of collimators: low energy, medium energy, and high energy collimators. As the collimators transitioned from low energy to high energy, the hole sizes, thickness, and septations between the holes also increased. Given a fixed septal thickness, the collimator resolution decreases with increased efficiency and also increasing distance of the source from the collimator. Pulse-height analyser determines the Full width at half maximum that selects certain photons to contribute to the final image, thus determining the collimator resolution.The individual holes limit photons which can be detected by the crystal to a cone shape; the point of the cone is at the midline center of any given hole and extends from the collimator surface outward. However, the collimator is also one of the sources of blurring within the image; lead does not totally attenuate incident gamma photons, there can be some crosstalk between holes. Unlike a lens, as used in visible light cameras, the collimator attenuates most (>99%) of incident photons and thus greatly limits the sensitivity of the camera system. Large amounts of radiation must be present so as to provide enough exposure for the camera system to detect sufficient scintillation dots to form a picture.: 128 Other methods of image localization (pinhole, rotating slat collimator with CZT) have been proposed and tested; however, none have entered widespread routine clinical use.
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Gamma camera
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Spatial resolution
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The best current camera system designs can differentiate two separate point sources of gamma photons located at 6 to 12 mm depending on distance from the collimator, the type of collimator and radio-nucleide. Spatial resolution decreases rapidly at increasing distances from the camera face. This limits the spatial accuracy of the computer image: it is a fuzzy image made up of many dots of detected but not precisely located scintillation. This is a major limitation for heart muscle imaging systems; the thickest normal heart muscle in the left ventricle is about 1.2 cm and most of the left ventricle muscle is about 0.8 cm, always moving and much of it beyond 5 cm from the collimator face. To help compensate, better imaging systems limit scintillation counting to a portion of the heart contraction cycle, called gating, however this further limits system sensitivity.
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Knowledge ark
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Knowledge ark
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A knowledge ark (also known as a doomsday ark or doomsday vault) is a collection of knowledge preserved in such a way that future generations would have access to said knowledge if all other copies of it were lost.
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Knowledge ark
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Knowledge ark
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Scenarios where access to information (such as the Internet) would become otherwise impossible could be described as existential risks or extinction-level events. A knowledge ark could take the form of a traditional library or a modern computer database. It could also be pictorial in nature, including photographs of important information, or diagrams of critical processes. A knowledge ark would have to be resistant to the effects of natural or man-made disasters in order to be viable. Such an ark should include, but would not be limited to, information or material relevant to the survival and prosperity of human civilization.
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Knowledge ark
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Knowledge ark
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Other types of knowledge arks might include genetic material, such as in a DNA bank. With the potential for widespread personal DNA sequencing becoming a reality, an individual might agree to store their genetic code in a digital or analog storage format which would enable later retrieval of that code. If a species was sequenced before extinction, its genome would still remain available for study.
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Knowledge ark
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Examples
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An example of a DNA bank is the Svalbard Global Seed Vault, a seedbank which is intended to preserve a wide variety of plant seeds (such as important crops) in case of their extinction.
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Knowledge ark
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Examples
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The Memory of Mankind project involves engraving human knowledge on clay tablets and storing it in a salt mine. The engravings are microscopic.A Lunar ark has been proposed which would store and transmit valuable information to receiver stations on Earth. The success of this would also depend on the availability of compatible receiver equipment on Earth, and adequate knowledge of that equipment's operation.
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Knowledge ark
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Examples
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The Arch Mission Foundation sent the Lunar Library, a 30 million page knowledge ark designed to survive for millions or billions of years in space, to the moon on the Israeli Beresheet spacecraft in 2019. The spacecraft experienced a crash landing. However, the library likely survived intact.The Phoenix mars lander (landed on surface of Mars in 2008) included the "Visions of Mars" DVD, a digital library about Mars designed to last for hundreds or thousands of years.
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Pseudostrabismus
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Pseudostrabismus
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Pseudostrabismus is the false appearance of crossed eyes. When the eyes are actually crossed or not completely aligned with one another, it is called strabismus. Pseudostrabismus is more likely to be observed in East Asian or Native American infants, due to the presence of epicanthic folds obscuring the medial aspect of each eye.
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Pseudostrabismus
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Pseudostrabismus
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Pseudostrabismus generally occurs in infants and toddlers, whose facial features are not fully developed. The bridge of their nose is wide and flat, creating telecanthus (increased distance between medial canthus of both eyes). With age, the bridge will narrow, and the epicanthic folds in the corner of the eyes will go away. This will cause the eyes to appear wider and thus not have the appearance of strabismus.
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Pseudostrabismus
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Pseudostrabismus
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To detect the difference between strabismus and pseudostrabismus, clinicians use a flashlight to shine into the child's eyes. When the child is looking at the light, a reflection can be seen on the front surface of the pupil. If the eyes are aligned with one another, the reflection from the light will be in the same spot of each eye. If strabismus is present, the reflection from the light will not be in the same spot of each eye.
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Pseudostrabismus
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Pseudostrabismus
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Rakel's Textbook of Family Medicine states, "A common misconception is that children with crossed eyes outgrow the condition, but this is generally not the case. This belief stems from the confusion between true strabismus and pseudostrabismus. When a child's eyes are truly crossed, it is always a serious condition and requires the care of an ophthalmologist."
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Threose
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Threose
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Threose is a four-carbon monosaccharide with molecular formula C4H8O4. It has a terminal aldehyde group rather than a ketone in its linear chain, and so is considered part of the aldose family of monosaccharides. The threose name can be used to refer to both the D- and L-stereoisomers, and more generally to the racemic mixture (D/L-, equal parts D- and L-) as well as to the more generic threose structure (absolute stereochemistry unspecified). The prefix "threo" which derives from threose (and "erythro" from a corresponding diastereomer erythrose) offer a useful way to describe general organic structures with adjacent chiral centers, where "the prefixes... designate the relative configuration of the centers". As is depicted in a Fischer projection of D-threose, the adjacent substituents will have a syn orientation in the isomer referred to as "threo", and are anti in the isomer referred to as "erythro".
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Mock trial
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Mock trial
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A mock trial is an act or imitation trial. It is similar to a moot court, but mock trials simulate lower-court trials, while moot court simulates appellate court hearings. Attorneys preparing for a real trial might use a mock trial consisting of volunteers as role players to test theories or experiment with each other. Mock trial is also the name of an extracurricular program in which students participate in rehearsed trials to learn about the legal system in a competitive manner. Interscholastic mock trials take place on all levels including primary school, middle school, high school, college, and law school. Mock trial is often taught in conjunction with a course in trial advocacy or takes place as an after school enrichment activity. Some gifted and talented programs may also take place in one.
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Mock trial
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Litigation related mock trials
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Litigators may use mock trials to assist with trial preparation and settlement negotiations of actual cases. Unlike school-related mock trials, these mock trials can take numerous forms depending on the information sought. For example, when faced with complex fact issues in a particular case, attorneys might convene a mini mock trial to try different methods of presenting their evidence, sometimes before a jury.
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Mock trial
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Competitive school-related mock trials around the world
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Asia Pacific Guam has been hosting the annual Asia-Pacific Invitational Mock Trial Competition. In 2011 and 2012, there were 14 teams from Guam, South Korea, and Saipan in its 4th annual competition. The competition was held at the Superior Court of Guam. The teams made up of mostly junior and senior students from high schools. The Champion of the 4th Annual Asia-Pacific Invitational Mock Trial Competition was Marianas Baptist Academy of Saipan.
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Mock trial
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Competitive school-related mock trials around the world
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Australia Mock trial competitions in Australia are held regionally. These include: The Law Society of South Australia Mock Trial Competition comprises a series of simulated court cases by students years 10, 11 and 12 from 32 schools in South Australia.
The Law Society of Western Australia Interschool Mock Trial Competition is held each year for students enrolled in years 10, 11 and 12 in Western Australia. There were 773 students representing 68 teams from 38 schools participated in 2011.
The Capital Region Mock Trial Competition is organized by University of Canberra. There were teams of schools in Australian Capital Territory region with year 10, 11 and 12 students.
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Mock trial
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Competitive school-related mock trials around the world
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The New South Wales Mock Trial Competition has been running since 1981 for students years 10 and 11 in New South Wales initially with 28 schools. There have also been international events with mock trial competitions between Australia and the United Kingdom. In 2008, schools from this region also traveled to New York City to compete in the Empire Mock Trial Competition. The first Asia-Australia mock trial competition via video conference between Australian teams and a Korean team was held in 2009.
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Mock trial
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Competitive school-related mock trials around the world
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Continental Europe Mock trials in continental Europe are less coordinated than their UK or US counterparts, but there are a few isolated examples. In Germany, the Faculty of Legal Sciences of the University of Regensburg organizes the REGINA Mock Trial. The University of Erlangen-Nuremberg organizes a mock trial specialized in administrative law. In Spain, there is a mock trial program specialized in insurance law coordinated by the Fundacion INADE-UDC Chair of Risk Management and Insurance.
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Mock trial
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Competitive school-related mock trials around the world
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United Kingdom The Bar National Mock Trial Competition involves students taking on the roles of barristers and witnesses and presenting their case against teams from other schools. Young Citizens, in association with His Majesty's Courts and Tribunal Service and the Bar Council, has been running Mock Trial Competitions annually since 1991. The competition consists of several regional heats and a national final to decide the winner. In 2022/23, 938 students aged between 15 - 18 years old from 144 schools participated in the competition. The heats were supported by over 70 legal volunteers, including judges, barristers and law students.The Magistrates Mock Trial Competition, organised by Young Citizens in association with the Magistrates Association, involves students taking on the roles of magistrates and witnesses. In 2022/2023, approximately 2,900 students aged between 12 - 14 years from 193 schools participated in the competition. The heats were supported by approximately 600 legal volunteers, including judges, barristers and law students.Mock Trials are primarily aimed at promoting confidence in public speaking as well as introducing young people to the justice system and legal profession.
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Mock trial
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Competitive school-related mock trials around the world
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In Scotland, The School Mock Court Case Project runs both primary and secondary school competitions, although has undertaken a number of international competitions. Currently some 100 schools, circa 3,000 students are involved. As of 2021, international schools started entering the programme, with over 16 countries taking part.
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Mock trial
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Competitive school-related mock trials around the world
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United States Competition framework Competitive mock trial functions in yearly cycles. Each year, a case packet is distributed to all participating schools in late summer to early fall. The case packet is a series of documents including the charges, penal code, stipulations, case law, and jury instructions as well as all exhibits and affidavits relevant to the case. During a mock trial, competitors are restricted to only the materials provided in the case packet and may not reference any outside sources. In order to prepare for competition, teams thoroughly read and analyze the case packet.
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Mock trial
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Competitive school-related mock trials around the world
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National mock trial teams consist of a minimum of six and a maximum of twelve official members. The size of state mock trial teams can vary; California, for example, allows up to 25 official team members. Each team prepares both sides of the case: prosecution/plaintiff and defense in a criminal trial, plaintiff and defense in a civil action. Each side is composed of two or three attorneys as well as two or three witnesses, all played by members of the team. Teams must be organized into two sides of five to six players for the prosecution/plaintiff and defense. It is important to note that high school mock trial is governed by state bar associations, meaning that cases, rules, and competition structure vary from state to state whereas all of college mock trial is governed by the American Mock Trial Association, meaning that every school uses the same case and is subject to the same rules.
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Mock trial
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Competitive school-related mock trials around the world
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Procedure The mock trial begins with the judge entering the courtroom. The judge then gives out the instructions to the jury (about what they are to listen to). Then if there is a pretrial motion, the defense and prosecution give their respective pretrial arguments. The judge then lets the prosecution or plaintiff give an opening statement. Following the prosecution/plaintiff's opening statement, the judge may offer the defense to deliver the opening statement during that time as well, or to wait until after the prosecution has presented all of its witnesses. After the opening statements, examination of the witnesses begins. The prosecution/plaintiff calls their witnesses first. Witnesses are sworn in by their team's bailiff/timekeeper. A student competitor attorney for the prosecution/plaintiff does a direct examination of the witness. Once the direct examination is complete, the opposing team may cross-examine the witness. After the cross-examination, if the first team chooses, they may re-direct the witness. Likewise, the other team may do a re-cross after a re-direct. However, re-direct and re-cross examinations are only limited to the scope of the previous examination conducted by opposing counsel. This process is repeated for the two remaining plaintiff witnesses. Once the prosecution/plaintiff have finished with their witnesses, the defense may give their opening statement if not delivered before, and then the process is repeated with the defense witnesses, having the defense attorneys direct and the plaintiff attorneys cross-examine.Once all of the witnesses have been examined, the trial moves to closing arguments. The prosecutor/plaintiff again goes first and has the option to reserve time beforehand for rebuttal. After the defense finishes their closing argument, the plaintiff may give their rebuttal argument if they still have time remaining. In some competitions, the rebuttal is limited to the scope of the defense's closing argument. Time limits are set at each level of competition to prevent the trials from running too long and to keep rounds of competition running smoothly. Time limits are as follows: Time limits may vary from state-to-state competitions. Please note that time is kept track of by the bailiff/timekeeper, who times their co-counsel's statements, examinations, and arguments. Time is stopped for objections.
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Mock trial
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Competitive school-related mock trials around the world
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Objections A main part of Mock Trial is the raising and arguing of objections given by opposing teams. Objections are raised when the opposing counsel attempts to bring in evidence or testimony that go against the rules of evidence. When an objection is raised, the judge may either overrule or sustain it immediately, or ask opposing counsel for their argument about why the testimony/evidence is admissible. Time is paused for objections, so an objection "battle" could theoretically go on for hours at a time until the judge makes a ruling. There is often an over all time limit given to rounds of competition, called "all loss" that prevent this from occurring. Mock Trial students receive an abridged version of Rules of Evidence to base their objections on in the case packet that contains the witness affidavits and other elements of the court case.
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Mock trial
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Competitive school-related mock trials around the world
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Judging There are several different ways that a mock trial can be judged. In one, the judges for scoring the mock trial consist of the presiding judge and two scoring judges, all of whom score the teams. In a second method, there are two scoring judges and the presiding judge, as in the first method, but the presiding judge does not score the teams, rather the judge simply votes or casts a ballot for one team or another. In yet another method of judging, there are three scoring judges and the presiding judge is not involved in the scoring of the teams. Often at college invitationals, there are two scoring judges, one of whom doubles as the presiding judge. Since enticing attorneys to judge is notoriously difficult (as judges are rarely compensated with more than a free lunch), it is rare to see more than two judges in a round at most competitions.
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Mock trial
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Competitive school-related mock trials around the world
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Unlike real law, the victorious team does not necessarily have to win on the merits of the case. Instead, evaluators score individual attorneys and witnesses on a 1–10 scale (though some states use different scales for high school competitions) based on each stage of the trial. These consist of the opening statements for the plaintiff and defense, each of the witnesses’ testimony, direct and cross-examination by attorneys, and the closing statements for both sides. The team with the highest total number of points is often, but not always, the team that wins the judge's verdict. Given this method of scoring, it is possible for the defendant to be found guilty or lose the case but for the defense team to still win the round.
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Mock trial
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Competitive school-related mock trials around the world
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In some competitions, points can be deducted from a team's score for testifying with information outside the scope of the mock trial materials and for unsportsmanlike conduct or abuse of objections. However, scores are completely at a judge's discretion, meaning that scores are subjective based on different evaluation criteria.
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Mock trial
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Competitive school-related mock trials around the world
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Power matching In the first round of the tournament, all of the teams are randomly matched to compete with each other. After the first round of some tournaments, teams are “power matched” to go up against other teams with similar records (e.g. in the second round, a 1–0 team will be matched with another 1–0 team). If there is a tie in record, the judges will use the number of ballots and total points earned to decide the matching. This allows for teams to compete with other teams of similar skill.
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Mock trial
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Competitive school-related mock trials around the world
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Of course, there are practical exceptions to the theory of power matching. Tab room coordinators who are creating brackets for each round may deviate from the rules of power matching in order to 1. allow each team to alternate between prosecution/plaintiff and defense between rounds, 2. avoid two teams from the same school competing against each other (Maryland Rule), 3. avoid having a team compete against a team it played in a prior round.
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Mock trial
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Competitive school-related mock trials around the world
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National championship format In the national championship format, which is also employed by invitationals across the country, the tournament is power matched through the last round. While this determines the strongest team at the tournament overall, it does not provide an accurate representation of 2nd, 3rd, 4th place teams, etc., because they might have lost multiple ballots to a strong team who placed first.
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Mock trial
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Competitive school-related mock trials around the world
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Power protection When tournaments are power protected, it means that the first rounds of competition are power matched as stated above. In the last round(s), however, the team with the strongest record is paired against the team with the weakest record. This ensures that the best teams do not knock each other out of the running for a rank. Rather, it's anticipated that the stronger team will win and protect their chance at a rank, while there is no harm done to the weaker team who is already out of reach of a trophy. Additionally, this method gives weaker teams exposure to stronger programs that they can learn from.
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Mock trial
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Competitive school-related mock trials around the world
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Levels of competition Elementary school At the elementary school level, the mock trial guide by American Bar Association suggests to use role-playing from scripted mock trials such as fairy tale mock trials as a way to introduce the concept of conflicts, trials, jury verdicts in civil trials, vocabulary of the court, damages, and the roles of individuals portrayed in the trial. Therefore, most of mock trials at this level are non-competitive classroom activities. There is no national competition for this level. However, a few states offer intrastate competitions. There are a couple of different formats for competitions at this level.
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Mock trial
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Competitive school-related mock trials around the world
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The first format focuses on how the cases are developed such as New Jersey Law Fair competitions. Students grades 3 to 6 are asked to generate, develop and write the case from their own idea to include details of the facts, issue, witnesses, statements, instructions, sub-issues, concepts and law. As the students at this age range may not know the details of applicable law, students are allowed to create their own law. There are no specific themes, students can choose any age-appropriate topics. The students are encouraged to do a role-playing in a mock trial based on the script that they have developed to involve other students in the classroom as juries in order to refine their case. Each team plays the roles of both side in their case during the mock trial. The winners will perform their case in the real court.In North Carolina, the competition has a different format which focuses more on presentation skills. All teams are given the same case which has been written prior to the competition and students are asked to perform role-playing on the case. North Carolina Elementary School Mock Trial Competition uses the winning entries from New Jersey Law Fair in the prior year as the cases for students to perform.Another format is to follow the standard format similar to the high school level but with less technical restriction. All teams are given the same material related to a case and prepare for the competition. Two teams compete in a live mock trial to represent two sides of the case. This format is used in the New Hampshire Bar Association's Mock Trial Competition. However, the first round of the competition is done by video submission where each team performs in both sides of the case. The qualified teams will be invited to the live competition with each team on each side of the case.
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Mock trial
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Competitive school-related mock trials around the world
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Middle school Although there is no national competition for middle/junior high school level, there are many intrastate competitions held by state/county level organizers: * With the exception of New Jersey, all competitions have similar format as in high school competitions with some rules relaxed. In New Jersey, the format is similar to the New Jersey Law Fair at the elementary school level with two specific themes that the teams can choose to develop their cases.
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Mock trial
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Competitive school-related mock trials around the world
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High school The mock trial program was started to allow high school students to experience a courtroom setting in a variety of hands-on roles. The mock trials are set up and structured just like a real court and are bound by the same rules. This can help the students to know exactly what role each of the different people in a court (judges, lawyers, witnesses, etc.) do in the judicial system. High school competitions are even held in functional courtrooms in the local City Hall to lend additional authenticity to the trial, are presided over by real judges, and the competing teams are typically coached and scored by practicing attorneys. Cases typically have to do with problems faced by teens, and includes competitors as witnesses. Each year the case for pre-Nationals competitions alternates between a Civil case and a Criminal case. The cases are set up in such a way that the witnesses, defendant, and prosecution (or plaintiff, for a Civil case) are all given gender neutral names to prevent gender based arguments from being brought up in the final arguments.
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