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PechaKucha (Japanese: ぺちゃくちゃ, IPA: [petɕa kɯ̥tɕa], chit-chat) is a storytelling format where a presenter shows 20 slides for 20 seconds of commentary each (6 minutes and 40 seconds total). At a PechaKucha Night, individuals gather at a venue to share personal presentations about their work. The PechaKucha format can be used, for example, in business presentations to clients or staff, as well as in education settings.

Inspired by their desire to "talk less, show more," Astrid Klein and Mark Dytham of Tokyo's Klein-Dytham Architecture (KDa) created PechaKucha in February 2003. It was a way to attract people to SuperDeluxe, their experimental event space in Roppongi, and to enable young designers to meet, show their work, and exchange ideas in 6 minutes 40 seconds.

In 2004, cities in Europe began hosting PK Nights and days, followed over the years by hundreds of others. As of April 2019, PKNs had been held in more than 1,142 cities worldwide. More than 3 million people have attended a PK Night.

PechaKucha is a registered trademark of PechaKucha, Inc.

In January 2018, PK's Astrid Klein, Mark Dytham, and Sean Smyth established PK, Inc. to create software to expand the PK platform.

🔗 Technology 🔗 Physics 🔗 Transport 🔗 Trains 🔗 Engineering

A Hyperloop is a proposed mode of passenger and freight transportation, first used to describe an open-source vactrain design released by a joint team from Tesla and SpaceX. Hyperloop is a sealed tube or system of tubes through which a pod may travel free of air resistance or friction conveying people or objects at high speed while being very efficient, thereby drastically reducing travel times over medium-range distances.

Elon Musk's version of the concept, first publicly mentioned in 2012, incorporates reduced-pressure tubes in which pressurized capsules ride on air bearings driven by linear induction motors and axial compressors.

The Hyperloop Alpha concept was first published in August 2013, proposing and examining a route running from the Los Angeles region to the San Francisco Bay Area, roughly following the Interstate 5 corridor. The Hyperloop Genesis paper conceived of a hyperloop system that would propel passengers along the 350-mile (560 km) route at a speed of 760 mph (1,200 km/h), allowing for a travel time of 35 minutes, which is considerably faster than current rail or air travel times. Preliminary cost estimates for this LA–SF suggested route were included in the white paper—US$6 billion for a passenger-only version, and US$7.5 billion for a somewhat larger-diameter version transporting passengers and vehicles—although transportation analysts had doubts that the system could be constructed on that budget; some analysts claimed that the Hyperloop would be several billion dollars overbudget, taking into consideration construction, development, and operation costs.

The Hyperloop concept has been explicitly "open-sourced" by Musk and SpaceX, and others have been encouraged to take the ideas and further develop them. To that end, a few companies have been formed, and several interdisciplinary student-led teams are working to advance the technology. SpaceX built an approximately 1-mile-long (1.6 km) subscale track for its pod design competition at its headquarters in Hawthorne, California.

🔗 United States

🔗 Australia 🔗 Canada 🔗 New Zealand 🔗 Psychology 🔗 United Kingdom 🔗 Sociology 🔗 Ireland

The tall poppy syndrome is the cultural phenomenon of jealous people holding back or directly attacking those who are perceived to be better than the norm, "cutting down the tall poppy". It describes a draw towards mediocrity.

Commonly in Australia and New Zealand, "Cutting down the tall poppy" is used to describe those who think too highly of themselves and it is seen by some as self-deprecating and by others as promoting modesty and egalitarianism.

🔗 Computing 🔗 Classical Greece and Rome 🔗 Greece 🔗 Astronomy 🔗 History of Science 🔗 Alternative Views 🔗 Time

The Antikythera mechanism (, ) is an ancient hand powered Greek analogue computer which has also been described as the first example of such device used to predict astronomical positions and eclipses for calendar and astrological purposes decades in advance. It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.

This artefact was retrieved from the sea in 1901, and identified on 17 May 1902 as containing a gear by archaeologist Valerios Stais, among wreckage retrieved from a shipwreck off the coast of the Greek island Antikythera. The instrument is believed to have been designed and constructed by Greek scientists and has been variously dated to about 87 BC, or between 150 and 100 BC, or to 205 BC, or to within a generation before the shipwreck, which has been dated to approximately 70–60 BC.

The device, housed in the remains of a 34 cm × 18 cm × 9 cm (13.4 in × 7.1 in × 3.5 in) wooden box, was found as one lump, later separated into three main fragments which are now divided into 82 separate fragments after conservation efforts. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 14 centimetres (5.5 in) in diameter and originally had 223 teeth.

It is a complex clockwork mechanism composed of at least 30 meshing bronze gears. A team led by Mike Edmunds and Tony Freeth at Cardiff University used modern computer x-ray tomography and high resolution surface scanning to image inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine.

Detailed imaging of the mechanism suggests that it had 37 gear wheels enabling it to follow the movements of the Moon and the Sun through the zodiac, to predict eclipses and even to model the irregular orbit of the Moon, where the Moon's velocity is higher in its perigee than in its apogee. This motion was studied in the 2nd century BC by astronomer Hipparchus of Rhodes, and it is speculated that he may have been consulted in the machine's construction.

The knowledge of this technology was lost at some point in antiquity. Similar technological works later appeared in the medieval Byzantine and Islamic worlds, but works with similar complexity did not appear again until the development of mechanical astronomical clocks in Europe in the fourteenth century. All known fragments of the Antikythera mechanism are now kept at the National Archaeological Museum in Athens, along with a number of artistic reconstructions and replicas of the mechanism to demonstrate how it may have looked and worked.

🔗 Video games

Doom, a first-person shooter game by id Software, was released in December 1993 and is considered one of the most significant and influential titles in video game history. Development began in November 1992, with programmers John Carmack and John Romero, artists Adrian Carmack and Kevin Cloud, and designer Tom Hall. Late in development, Hall was replaced by Sandy Petersen and programmer Dave Taylor joined. The music and sound effects were created by Bobby Prince.

The Doom concept was proposed in late 1992, after the release of Wolfenstein 3D and its sequel Spear of Destiny. John Carmack was working on an improved 3D game engine from those games, and the team wanted to have their next game take advantage of his designs. Several ideas were proposed, including a new game in their Commander Keen series, but John proposed a game about using technology to fight demons inspired by the Dungeons & Dragons campaigns the team played. The initial months of development were spent building prototypes, while Hall created the Doom Bible, a design document for his vision of the game and its story; after id released a grandiose press release touting features that the team had not yet begun working on, the Doom Bible was rejected in favor of a plotless game with no design document at all.

Over the next six months, Hall designed levels based on real military bases, Romero built features, and artists Adrian and Cloud created textures and demons based on clay models they built. Hall's level designs, however, were deemed uninteresting and Romero began designing his own levels; Hall, increasingly frustrated with his limited influence, was fired in July. He was replaced by Petersen in September, and the team worked increasingly long hours until the game was completed in December 1993. Doom was self-published by id on December 10, 1993, and immediately downloaded by thousands of players.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Asian military history 🔗 Military history/Southeast Asian military history 🔗 Vietnam

Operation Popeye (Project Controlled Weather Popeye / Motorpool / Intermediary-Compatriot) was a highly classified weather modification program in Southeast Asia during 1967–1972. The cloud seeding operation during the Vietnam War ran from March 20, 1967 until July 5, 1972 in an attempt to extend the monsoon season, specifically over areas of the Ho Chi Minh Trail. The operation was used to induce rain and extend the East Asian Monsoon season in support of U.S. government efforts related to the War in Southeast Asia.

The former U.S. Secretary of Defense, Robert S. McNamara, was aware that there might be objections raised by the international scientific community but said in a memo to the president that such objections had not in the past been a basis for prevention of military activities considered to be in the interests of U.S. national security.

The chemical weather modification program was conducted from Thailand over Cambodia, Laos, and Vietnam and allegedly sponsored by Secretary of State Henry Kissinger and CIA without the authorization of then Secretary of Defense Melvin Laird who had categorically denied to Congress that a program for modification of the weather for use as a tactical weapon even existed.

🔗 Film 🔗 Film/Documentary films 🔗 Women scientists

Top Secret Rosies: The Female "Computers" of WWII is a 2010 documentary film directed by LeAnn Erickson. The film is focused on recognizing the contributions of women during WWII, serving as human computers and six of whom went on to program one of the earliest computers, the ENIAC. Their work helped the United States improve the accuracy of weaponry as most conducted ballistics analysis. The film officially premiered on November 1 on PBS.

🔗 Games

Nomic is a game created in 1982 by philosopher Peter Suber in which the rules of the game include mechanisms for the players to change those rules, usually beginning through a system of democratic voting.

Nomic is a game in which changing the rules is a move. In that respect it differs from almost every other game. The primary activity of Nomic is proposing changes in the rules, debating the wisdom of changing them in that way, voting on the changes, deciding what can and cannot be done afterwards, and doing it. Even this core of the game, of course, can be changed.

The initial ruleset was designed by Peter Suber, and first published in Douglas Hofstadter's column Metamagical Themas in Scientific American in June 1982. The column discussed Suber's then-upcoming book, The Paradox of Self-Amendment, which was published some years later. Nomic now refers to many games, all based on the initial ruleset.

The game is in some ways modeled on modern government systems. It demonstrates that in any system where rule changes are possible, a situation may arise in which the resulting laws are contradictory or insufficient to determine what is in fact legal. Because the game models (and exposes conceptual questions about) a legal system and the problems of legal interpretation, it is named after νόμος (nomos), Greek for "law".

While the victory condition in Suber's initial ruleset is the accumulation of 100 points by the roll of dice, he once said that "this rule is deliberately boring so that players will quickly amend it to please themselves". Players can change the rules to such a degree that points can become irrelevant in favor of a true currency, or make victory an unimportant concern. Any rule in the game, including the rules specifying the criteria for winning and even the rule that rules must be obeyed, can be changed. Any loophole in the ruleset, however, may allow the first player to discover it the chance to pull a "scam" and modify the rules to win the game. Complicating this process is the fact that Suber's initial ruleset allows for the appointment of judges to preside over issues of rule interpretation.

🔗 Engineering 🔗 Metalworking

Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes can avoid, or greatly reduce, the need to use metal removal processes, thereby drastically reducing yield losses in manufacture and often resulting in lower costs.

Powder metallurgy is also used to make unique materials impossible to get from melting or forming in other ways. A very important product of this type is tungsten carbide (WC). WC is used to cut and form other metals and is made from WC particles bonded with cobalt. It is very widely used in industry for tools of many types and globally ~50,000 tonnes/year (t/y) is made by PM. Other products include sintered filters, porous oil-impregnated bearings, electrical contacts and diamond tools.

Since the advent of industrial production–scale metal powder–based additive manufacturing (AM) in the 2010s, selective laser sintering and other metal AM processes are a new category of commercially important powder metallurgy applications.