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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 60–300 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]

Human Universal Load Carrier, or HULC, is un-tethered, hydraulic-powered anthropomorphic exoskeleton developed by Berkeley Bionics. It is intended to help soldiers in combat carry a load of up to 200 pounds at a top speed of 10 miles per hour for extended periods of time. After being under development at Berkeley Robotics and Human Engineering Laboratory since 2000, the system was announced publicly at the AUSA Winter Symposium on February 26, 2009 when an exclusive licensing agreement was reached with Lockheed Martin. Loads attach to the exoskeleton system and are carried by the exoskeleton, bypassing the human operator. The effective forces felt by the operator are dramatically diminished reducing the risk of muscularskeletal injuries. The HULC provides power assistance at the hip and knee joint. The innovative hydraulic architecture is highly efficient enabling the system to run on batteries. Other exoskeleton systems, such as the Raytheon/SARCOS XOS 2 system are tethered to a power generator. Lockheed Martin announced that it is evaluating fuel cell power sources to increase the duration to support a 72 hour mission . HULC is also easy to put on. It arrives folded in a small package, so soldiers just have to stretch out a leg and step into foot beds underneath the boot. Straps then wrap around the thighs, waist and shoulders. Sensors in the foot pads relay information to an onboard microcomputer that moves the hydraulic system to amplify and enhance the wearer's movement. The flexibility of the system allows soldiers to run, walk, kneel, crawl, and even go into low squats. Lockheed Martin originally developed the HULC to assist soldiers during combat. It could be used to help lift heavy loads while exerting minimal effort, with soldiers currently going into combat with up to 130 pounds of combat gear. Also, it could be used as a framework for body armor or sensor arrays that would allow for better situational awareness during combat. Lockheed Martin is also exploring exoskeleton designs to support industrial and medical applications. [READ THE REST OF THIS ARTICLE]

A Rube Goldberg machine, device, or apparatus is a deliberately over-engineered machine that performs a very simple task in a very complex fashion, usually including a chain reaction. The expression is named after American cartoonist and inventor Rube Goldberg. Since then, the expression has expanded to denote any form of overly confusing or complicated system. For example, news headlines include "Is Rep. Bill Thomas the Rube Goldberg of Legislative Reform?" and "Retirement 'insurance' as a Rube Goldberg machine". Rube Goldberg's cartoons became well known for depicting complex devices that performed simple tasks in indirect, convoluted ways. An example on the right is Goldberg's "Professor Butts and the Self-Operating Napkin", which was later reprinted in the postcard book, Rube Goldberg's Inventions!, compiled by Maynard Frank Wolfe from the Rube Goldberg Archives. The "Self-Operating Napkin" is activated when the soup spoon (A) is raised to mouth, pulling string (B) and thereby jerking ladle (C) which throws cracker (D) past parrot (E). Parrot jumps after cracker and perch (F) tilts, upsetting seeds (G) into pail (H). Extra weight in pail pulls cord (I), which opens and lights automatic cigar lighter (J), setting off skyrocket (K) which causes sickle (L) to cut string (M) and allow pendulum with attached napkin to swing back and forth, thereby wiping chin. In 1931, the Merriam–Webster dictionary adopted the word "Rube Goldberg" as an adjective defined as accomplishing something simple through complex means. In early 1987, Purdue University in Indiana started the annual National Rube Goldberg Machine Contest, organized by the Phi Chapter of Theta Tau, a national engineering fraternity. In 2009, the Epsilon Chapter of Theta Tau established a similar annual contest at the University of California, Berkeley. Since around 1997, the kinetic artist Arthur Ganson has been the emcee of the annual "Friday After Thanksgiving" (FAT) competition sponsored by the MIT Museum in Cambridge, Massachusetts. Teams of contestants construct elaborate Rube Goldberg style chain-reaction machines on tables arranged around a large gymnasium. Each apparatus is linked by a string to its predecessor and successor machine. The initial string is ceremonially pulled, and the ensuing events are videotaped in closeup, and simultaneously projected on large screens for viewing by the live audience. After the entire cascade of events has finished, prizes are then awarded in various categories and age levels. Videos from several previous years' contests are viewable on the MIT Museum website. [READ THE REST OF THIS ARTICLE]

The Russian Woodpecker was a notorious Soviet signal that could be heard on the shortwave radio bands worldwide between July 1976 and December 1989. It sounded like a sharp, repetitive tapping noise, at 10 Hz, giving rise to the "Woodpecker" name. The random frequency hops disrupted legitimate broadcast, amateur radio, and utility transmissions and resulted in thousands of complaints by many countries worldwide. The signal was long believed to be that of an over-the-horizon radar (OTH) system. This theory was publicly confirmed after the fall of the Soviet Union, and is now known to be the Duga-3 system, part of the Soviet ABM early-warning network. This was something that NATO military intelligence was well aware of all along, having photographed it and giving it the NATO reporting name Steel Yard. Starting in the late 1980s, even as the FCC was publishing studies of the signal, the signals became less frequent, and in 1989 disappeared altogether. Although the reasons for the eventual shutdown of the Duga-3 systems have not been made public, the changing strategic balance with the fall of the cold war in the late 1980s likely had a major part to play. Another factor was the success of the US-KS early-warning satellites, which entered preliminary service in the early 1980s, and by this time had grown into a complete network. The satellite system provides immediate, direct and highly secure warnings, whereas any radar-based system is subject to jamming, and the effectiveness of OTH systems is also subject to atmospheric conditions. According to some reports, the Komsomolsk-na-Amure installation in Siberia was taken off combat alert duty in November 1989, and some of its equipment was subsequently scrapped. Google Maps photography of the area shows that the antenna has been removed. The original Duga-3 site lies within the 30 kilometer Zone of Alienation around the Chernobyl power plant. It appears to have been permanently deactivated, since their continued maintenance did not figure in the negotiations between Russia and Ukraine over the active early warning radars at Mukachevo and Sevastopol. The antenna still stands, however, and has been used by amateurs as a transmission tower (using their own antennas) and has been extensively photographed. [READ THE REST OF THIS ARTICLE] is not affiliated with or endorsed by wikipedia. wikipedia and the wikipedia globe are registered trademarks of
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