Wikisnaps! We find what's interesting on Wikipedia, so you don't have to!

A 3-D (three-dimensional) film or S3D (stereoscopic 3D) film is a motion picture that enhances the illusion of depth perception. Derived from stereoscopic photography, a regular motion picture camera system is used to record the images as seen from two perspectives (or computer-generated imagery generates the two perspectives in post-production), and special projection hardware and/or eyewear are used to provide the illusion of depth when viewing the film. 3-D films are not limited to feature film theatrical releases; television broadcasts and direct-to-video films have also incorporated similar methods, primarily for marketing purposes. 3-D films have existed in some form since the 1950s, but had been largely relegated to a niche in the motion picture industry because of the costly hardware and processes required to produce and display a 3-D film, and the lack of a standardized format for all segments of the entertainment business. Nonetheless, 3-D films were prominently featured in the 1950s in American cinema, and later experienced a worldwide resurgence in the 1980s and '90s driven by IMAX high-end theaters and Disney themed-venues. 3-D films became more and more successful throughout the 2000s, culminating in the unprecedented success of 3-D presentations of Avatar in December 2009 and January 2010. Stereoscopic motion pictures can be produced through a variety of different methods. Over the years the popularity of systems being widely employed in movie theaters has waxed and waned. Though anaglyph was sometimes used prior to 1948, during the early "Golden Era" of 3-D cinematography of the 1950s the polarization system was used for every single feature length movie in the United states, and all but one short film. In the 21st century, polarization 3-D systems have continued to dominate the scene, though during the 60s and 70s some classic films which were converted to anaglyph for theaters not equipped for polarization, and were even shown in 3-D on TV. In the years following the mid 80s, some movies were made with short segments in anaglyph 3D. The following are some of the technical details and methodologies employed in some of the more notable 3-D movie systems that have been developed. In the case of RealD a circularly polarizing liquid crystal filter which can switch polarity 144 times per second is placed in front of the projector lens. Only one projector is needed, as the left and right eye images are displayed alternately. Sony features a new system called RealD XLS, which shows both circular polarized images simultaneously: a single 4K projector (40962160 resolution) displays both 2K images (2048858 resolution) on top of each other at the same time, a special lens attachment polarizes and projects the images. [READ THE REST OF THIS ARTICLE]

The Goliath Bird-eating Spider (also called the Goliath Birdeater) (Theraphosa blondi) is an arachnid belonging to the tarantula family, Theraphosidae, and is considered to be the largest spider (by leg-span) in the world.[citation needed] The spider was named by explorers from the Victorian era, who witnessed one eating a hummingbird. It is native to the rain forest regions of northern South America. These spiders have up to a 12 inch (30 cm) leg span and can weigh over 6 ounces. Wild Goliath birdeaters are a deep-burrowing species, found commonly in marshy or swampy areas, usually living in burrows that they have dug or which have been abandoned by other burrowing creatures. Females mature in 3 to 4 years and have an average life span of 15 to 25 years. Males die soon after maturity and have a lifespan of three to six years. Colors range from dark to light brown with faint markings on the legs. Birdeaters have hair on their bodies, abdomens, and legs. The female lays anywhere from 100 to 200 eggs, which hatch into spiderlings within two months. The Goliath birdeater is fairly harmless to humans, as are most species of tarantulas. Like all tarantulas, they have fangs large enough to break the skin of a human (.75 to 1 and a half inches). They carry venom in their fangs and have been known to bite when threatened, but the venom is relatively harmless and its effects are comparable to those of a wasp's sting. Also when threatened they rub their abdomen with their hind legs and release hairs that are a severe irritant to the skin and mucus membranes. Tarantulas generally bite humans only in self-defense, and these bites do not always result in envenomation (known as a "dry bite"). The Goliath birdeater has poor eyesight and mainly relies on vibrations in the ground that it can sense from its burrow. Despite its name, the Goliath Birdeater does not normally eat birds. As with other species of spider, (specifically tarantulas), their diet consists primarily of insects and other invertebrates. However, because of its naturally large size, it is not uncommon for this species to kill and consume a variety of vertebrates. In the wild, larger species of tarantula have been seen feeding on rodents, lizards, and even bats. In captivity, the Goliath Birdeater's staple diet should consist of cockroaches, anoles, and an occasional small mouse. Spiderlings and juveniles can be fed crickets or cockroaches that do not exceed the body length of the individual. [READ THE REST OF THIS ARTICLE]

A leptocephalus is the flat and transparent larva of the eel, marine eels, and other members of the Superorder Elopomorpha. These fishes with a leptocephalus larva stage include the most familiar eels such as the conger, moray eel, and garden eel, and the freshwater eels of the family Anguillidae, plus more than 10 other families of lesser-known types of marine eels. These are all true eels of the order Anguilliformes. The fishes of the other four traditional orders of elopomorph fishes that have this type of larva are more diverse in their body forms and include the tarpon, bonefish, spiny eel, and pelican eel. Leptocephali (more than one leptocephalus) all have laterally compressed bodies that contain transparent jelly-like substances on the inside of the body and a thin layer of muscle on the outside. Their body organs are small, and this combination of features results in them being very transparent when they are alive. They also lack red blood cells until they begin to metamorphose into the juvenile glass eel stage when they start to look like eels. Leptocephali differ from most fish larvae because they grow to much larger sizes (about 60300 mm and sometimes larger) and have long larval periods of about 3 months to more than a year. They move with typical anguilliform swimming motions and can swim both forwards and backwards. Their food source was difficult to determine because no zooplankton, which are the typical food of fish larvae, were ever seen in their guts. It was recently found though, that they appear to feed on tiny particles floating free in the ocean, which are often referred to as marine snow. Leptocephalus larvae live primarily in the upper 100 meters of the ocean at night, and often a little deeper during the day. Leptocephali are present worldwide in the ocean from southern temperate to tropical latitudes, where adult eels and their close relatives live. [READ THE REST OF THIS ARTICLE]

The M18A1 Claymore is a directional anti-personnel mine used by the U.S. military. It was named after the large Scottish sword by its inventor, Norman A. MacLeod. It is used primarily in ambushes and as an anti-infiltration device against enemy infantry. It is also of some use against unarmored vehicles. The M18A1 Claymore mine consists of a horizontally convex black plastic case (inert training versions are gray), which is vertically concave. The shape was developed through experimentation to deliver the optimum distribution of fragments at 50m range. The case has the words "Front Toward Enemy" embossed on the front surface of the mine. A simple open sight on the top surface is provided for aiming the mine. Two pairs of scissor legs attached to the bottom support the mine and allow it to be aimed vertically. Either side of the sight are fuse wells set at 45 degrees to the vertical. Internally the mine contains a layer of C-4 explosive on top of which is a matrix of approximately seven hundred 1/8 inch diameter steel balls (about as big as #4 birdshot) set into an epoxy resin. When the M18A1 is detonated, the explosion drives the matrix of 700 spherical fragments out of the mine at a velocity of 1,200 m/s, at the same time breaking the matrix into individual fragments. The spherical steel balls are projected in a 60 fan-shaped pattern that is 2m high and 50m wide at a range of 50m. The force of the explosion deforms the relatively soft steel fragments into a shape similar to a .22 rimfire projectile. The Claymore mine is typically deployed in one of three modes: Controlled, Uncontrolled, or Time-delayed. When in use by the U.S. military, the M18A1 Claymore Anti-Personnel Mine is most often command-detonated. Such use is permitted by the Mine Ban Treaty. However, use of Claymore mines in uncontrolled (tripwire) mode is prohibited by the treaty. Because of this uncontrolled mode, it is frequently listed in efforts to ban anti-personnel mines. [READ THE REST OF THIS ARTICLE] is not affiliated with or endorsed by wikipedia. wikipedia and the wikipedia globe are registered trademarks of
article content reproduced in compliance with wikipedia's copyright policy and gnu free documentation license
view our privacy policy and terms of service here