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Maxima () is a computer algebra system (CAS) based on a 1982 version of Macsyma. It is written in Common Lisp and runs on all POSIX platforms such as macOS, Unix, BSD, and Linux, as well as under Microsoft Windows and Android. It is free software released under the terms of the GNU General Public License (GPL).

A broad arrow, of which a pheon is a variant, is a stylised representation of a metal arrowhead, comprising a tang and two barbs meeting at a point. It is a symbol used traditionally in heraldry, most notably in England, and later by the British government to mark government property. It became particularly associated with the Board of Ordnance, and later the War Department and the Ministry of Defence. It was exported to other parts of the British Empire, where it was used in similar official contexts.

In heraldry, the arrowhead generally points downwards, whereas in other contexts it more usually points upwards.

MOOSE, originally an acronym for Man Out Of Space Easiest but later changed to the more professional-sounding Manned Orbital Operations Safety Equipment, was a proposed emergency "bail-out" system capable of bringing a single astronaut safely down from Earth orbit to the planet's surface. The design was proposed by General Electric in the early 1960s. The system was quite compact, weighing 200 lb (91 kg) and fitting inside a suitcase-sized container. It consisted of a small twin-nozzle rocket motor sufficient to deorbit the astronaut, a PET film bag 6 ft (1.8 m) long with a flexible 0.25 in (6.4 mm) ablative heat shield on the back, two pressurized canisters to fill it with polyurethane foam, a parachute, radio equipment and a survival kit.

The astronaut would leave the vehicle in a space suit, climb inside the plastic bag, and then fill it with foam. The bag had the shape of a blunt cone, with the astronaut embedded in its base facing the apex of the cone. The rocket pack would protrude from the bag and be used to slow the astronaut's orbital speed enough so that he would reenter Earth's atmosphere, and the foam-filled bag would act as insulation during the subsequent aerobraking. Finally, once the astronaut had descended to 30,000 ft (9.1 km) where the air was sufficiently dense, the parachute would automatically deploy and slow the astronaut's fall to 17 mph (7.6 m/s). The foam heat shield would serve a final role as cushioning when the astronaut touched down and as a flotation device should they land on water. The radio beacon would guide rescuers.

General Electric performed preliminary testing on some of the components of the MOOSE system, including flying samples of heat shield material on a Mercury mission, inflating a foam-filled bag with a human subject embedded inside, and test-dropping dummies and a human subject in MOOSE foam shields short distances. U.S. Air Force Capt. Joe Kittinger's historic freefall from a balloon at 103,000 ft (31,000 m) in August 1960 also helped demonstrate the feasibility of such extreme parachuting. However, the MOOSE system was nonetheless always intended as an extreme emergency measure when no other option for returning an astronaut to Earth existed; falling from orbit protected by nothing more than a spacesuit and a bag of foam was unlikely to ever become a particularly safe—or enticing—maneuver.

Neither NASA nor the U.S. Air Force expressed an interest in the MOOSE system, and so by the end of the 1960s the program had been quietly shelved.

In marketing strategy, first-mover advantage (FMA) is the advantage gained by the initial ("first-moving") significant occupant of a market segment. First-mover advantage may be gained by technological leadership, or early purchase of resources.

A market participant has first-mover advantage if it is the first entrant and gains a competitive advantage through control of resources. With this advantage, first-movers can be rewarded with huge profit margins and a monopoly-like status.

Not all first-movers are rewarded. If the first-mover does not capitalize on its advantage, its "first-mover disadvantages" leave opportunity for new entrants to enter the market and compete more effectively and efficiently than the first-movers; such firms have "second-mover advantage".

Raku rules are the regular expression, string matching and general-purpose parsing facility of Raku, and are a core part of the language. Since Perl's pattern-matching constructs have exceeded the capabilities of formal regular expressions for some time, Raku documentation refers to them exclusively as regexes, distancing the term from the formal definition.

Raku provides a superset of Perl 5 features with respect to regexes, folding them into a larger framework called rules, which provide the capabilities of a parsing expression grammar, as well as acting as a closure with respect to their lexical scope. Rules are introduced with the rule keyword, which has a usage quite similar to subroutine definitions. Anonymous rules can be introduced with the regex (or rx) keyword, or simply be used inline as regexes were in Perl 5 via the m (matching) or s (substitution) operators.

The Schaffer–Vega diversity system (SVDS) was a wireless guitar system developed in 1975–76, engineered and prototyped by Ken Schaffer in New York City, and manufactured by the Vega Corporation, El Monte, California. A handheld microphone version was introduced in 1977.

The system was the first cordless system to be adopted by major rock acts because it solved technical problems common to earlier wireless systems. The reliable sound and freedom of movement it provided paved the way for bands to tour with large multi-level stages in arenas. Schaffer-Vegas were used in the late 1970s and early 1980s by many rock bands such as Pink Floyd (namely guitarist David Gilmour), the Rolling Stones, AC/DC and Kiss.

The 996 working hour system (Chinese: 996工作制) is a work schedule commonly practiced by some companies in the People's Republic of China. It derives its name from its requirement that employees work from 9:00 am to 9:00 pm, 6 days per week; i.e. 72 hours per week. A number of Chinese internet companies have adopted this system as their official work schedule. Critics argue that the 996 working hour system is a flagrant violation of Chinese law.

In March 2019 an "anti-996" protest was launched via GitHub.

An automated vacuum waste collection system, also known as pneumatic refuse collection, or automated vacuum collection (AVAC), transports waste at high speed through underground pneumatic tubes to a collection station where it is compacted and sealed in containers. When the container is full, it is transported away and emptied. The system helps facilitate separation and recycling of waste.

The process begins with the deposit of trash into intake hatches, called portholes, which may be specialized for waste, recycling, or compost. Portholes are located in public areas and on private property where the owner has opted in. The waste is then pulled through an underground pipeline by air pressure difference created by large industrial fans, in response to porthole sensors that indicate when the trash needs to be emptied and help ensure that only one kind of waste material is travelling through the pipe at a time. The pipelines converge on a central processing facility that uses automated software to direct the waste to the proper container, from there to be trucked to its final location, such as a landfill or composting plant.

The Great Debate, also called the Shapley–Curtis Debate, was held on 26 April 1920 at the Smithsonian Museum of Natural History, between the astronomers Harlow Shapley and Heber Curtis. It concerned the nature of so-called spiral nebulae and the size of the universe; Shapley believed that distant nebulae were relatively small and lay within the outskirts of Earth's home galaxy, while Curtis held that they were in fact independent galaxies, implying that they were exceedingly large and distant.

The two scientists first presented independent technical papers about "The Scale of the Universe" during the day and then took part in a joint discussion that evening. Much of the lore of the Great Debate grew out of two papers published by Shapley and by Curtis in the May 1921 issue of the Bulletin of the National Research Council. The published papers each included counter arguments to the position advocated by the other scientist at the 1920 meeting.

In the aftermath of the public debate, scientists have been able to verify individual pieces of evidence from both astronomers, but on the main point of the existence of other galaxies, Curtis has been proven correct.

The half-life of knowledge or half-life of facts is the amount of time that has to elapse before half of the knowledge or facts in a particular area is superseded or shown to be untrue. These coined terms belong to the field of quantitative analysis of science known as scientometrics.

These ideas of half-life applied to different fields differ from the concept of half-life in physics in that there is no guarantee that the knowledge or facts in areas of study are declining exponentially. It is unclear that there is any way to establish what constitutes "knowledge" in a particular area, as opposed to mere opinion or theory.

An engineering degree went from having a half life of 35 years in ca. 1930 to about 10 years in 1960.

A Delphi Poll showed that the half life of psychology as measured in 2016 ranged from 3.3 to 19 years depending on the specialty, with an average of a little over 7 years.

It has also been used in Christian missiology to increase the effectiveness of their teachings.