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🔗 Aviation 🔗 Organized Labour

The Professional Air Traffic Controllers Organization or PATCO was a United States trade union that operated from 1968 until its decertification in 1981 following an illegal strike that was broken by the Reagan Administration. According to labor historian Joseph A. McCartin, the 1981 strike and defeat of PATCO was "one of the most important events in late twentieth century U.S. labor history".

🔗 Computing 🔗 Telecommunications 🔗 Computing/Software 🔗 Computing/Networking

ZMODEM is a file transfer protocol developed by Chuck Forsberg in 1986, in a project funded by Telenet in order to improve file transfers on their X.25 network. In addition to dramatically improved performance compared to older protocols, ZMODEM also offered restartable transfers, auto-start by the sender, an expanded 32-bit CRC, and control character quoting supporting 8-bit clean transfers, allowing it to be used on networks that would not pass control characters.

In contrast to most transfer protocols developed for bulletin board systems (BBSs), ZMODEM was not directly based on, nor compatible with, the seminal XMODEM. Many variants of XMODEM had been developed in order to address one or more of its shortcomings, and most remained backward compatible and would successfully complete transfers with "classic" XMODEM implementations.

ZMODEM eschewed backward compatibility in favor of producing a radically improved protocol. It performed as well or better than any of the high-performance varieties of XMODEM, did so over links that previously didn't work at all, like X.25, or had poor performance, like Telebit modems, and included useful features found in few or no other protocols. ZMODEM became extremely popular on bulletin board systems (BBS) in the early 1990s, becoming a standard as widespread as XMODEM had been before it.

🔗 Cryptography 🔗 Cryptography/Computer science

The Cardan grille is a method of writing secret messages using a grid.

🔗 Computer science 🔗 Mathematics 🔗 Systems

An L-system or Lindenmayer system is a parallel rewriting system and a type of formal grammar. An L-system consists of an alphabet of symbols that can be used to make strings, a collection of production rules that expand each symbol into some larger string of symbols, an initial "axiom" string from which to begin construction, and a mechanism for translating the generated strings into geometric structures. L-systems were introduced and developed in 1968 by Aristid Lindenmayer, a Hungarian theoretical biologist and botanist at the University of Utrecht. Lindenmayer used L-systems to describe the behaviour of plant cells and to model the growth processes of plant development. L-systems have also been used to model the morphology of a variety of organisms and can be used to generate self-similar fractals.

🔗 Video games

Bob's Game (stylized as "bob's game") was a role-playing video game being developed by independent video game developer Robert Pelloni since 2003/2004. The project is most notable for Pelloni developing the game using open source software development tools and Nintendo's refusal to license him the official SDK as well as Bob's response to that decision.

🔗 Color

YInMn Blue (for yttrium, indium, manganese), also known as Oregon Blue, Mas Blue, or Yin Min Blue, is an inorganic blue pigment that was discovered accidentally by Professor Mas Subramanian and his then-graduate student Andrew E. Smith at Oregon State University in 2009. It is the first inorganic blue pigment discovered in 200 years, since cobalt blue was identified in 1802.

The compound has a unique trigonal bipyramidal structure, and further research has discovered it may be modified to create green, purple, and orange pigments.

🔗 Numbers 🔗 Canada 🔗 Arctic 🔗 Writing systems 🔗 Indigenous peoples of North America 🔗 Canada/Canadian Territories 🔗 Alaska

Kaktovik Iñupiaq numerals are a featural positional numeral system created by Alaskan Iñupiat.

Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students from Kaktovik, Alaska invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan Iñupiat and has been considered in other countries where Inuit languages are spoken.

The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (I0), forty as a two and a zero (V0), four hundred as a one and two zeros (I00), eight hundred as a two and two zeros (V00), etc.

🔗 Biography 🔗 Mathematics 🔗 Biography/science and academia 🔗 History of Science 🔗 Switzerland 🔗 Genealogy

The Bernoulli family (German pronunciation: [bɛʁˈnʊli]) of Basel was a patrician family, notable for having produced eight mathematically gifted academics who, among them, contributed substantially to the development of mathematics and physics during the early modern period.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Business 🔗 Politics 🔗 Psychology 🔗 Marketing & Advertising

Serial-position effect is the tendency of a person to recall the first and last items in a series best, and the middle items worst. The term was coined by Hermann Ebbinghaus through studies he performed on himself, and refers to the finding that recall accuracy varies as a function of an item's position within a study list. When asked to recall a list of items in any order (free recall), people tend to begin recall with the end of the list, recalling those items best (the recency effect). Among earlier list items, the first few items are recalled more frequently than the middle items (the primacy effect).

One suggested reason for the primacy effect is that the initial items presented are most effectively stored in long-term memory because of the greater amount of processing devoted to them. (The first list item can be rehearsed by itself; the second must be rehearsed along with the first, the third along with the first and second, and so on.) The primacy effect is reduced when items are presented quickly and is enhanced when presented slowly (factors that reduce and enhance processing of each item and thus permanent storage). Longer presentation lists have been found to reduce the primacy effect.

One theorised reason for the recency effect is that these items are still present in working memory when recall is solicited. Items that benefit from neither (the middle items) are recalled most poorly. An additional explanation for the recency effect is related to temporal context: if tested immediately after rehearsal, the current temporal context can serve as a retrieval cue, which would predict more recent items to have a higher likelihood of recall than items that were studied in a different temporal context (earlier in the list). The recency effect is reduced when an interfering task is given. Intervening tasks involve working memory, as the distractor activity, if exceeding 15 to 30 seconds in duration, can cancel out the recency effect. Additionally, if recall comes immediately after the test, the recency effect is consistent regardless of the length of the studied list, or presentation rate.

Amnesiacs with poor ability to form permanent long-term memories do not show a primacy effect, but do show a recency effect if recall comes immediately after study. People with Alzheimer's disease exhibit a reduced primacy effect but do not produce a recency effect in recall.

🔗 Music theory

The Parsons code, formally named the Parsons code for melodic contours, is a simple notation used to identify a piece of music through melodic motion — movements of the pitch up and down. Denys Parsons developed this system for his 1975 book The Directory of Tunes and Musical Themes. Representing a melody in this manner makes it easier to index or search for pieces, particularly when the notes values are unknown.

The book was also published in Germany in 2002 and reprinted by Piatkus as The Directory of Classical Themes in 2008.