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🔗 Computer science

Boids is an artificial life program, developed by Craig Reynolds in 1986, which simulates the flocking behaviour of birds. His paper on this topic was published in 1987 in the proceedings of the ACM SIGGRAPH conference. The name "boid" corresponds to a shortened version of "bird-oid object", which refers to a bird-like object. Incidentally, "boid" is also a New York Metropolitan dialect pronunciation for "bird".

As with most artificial life simulations, Boids is an example of emergent behavior; that is, the complexity of Boids arises from the interaction of individual agents (the boids, in this case) adhering to a set of simple rules. The rules applied in the simplest Boids world are as follows:

• separation: steer to avoid crowding local flockmates
• alignment: steer towards the average heading of local flockmates
• cohesion: steer to move towards the average position (center of mass) of local flockmates

More complex rules can be added, such as obstacle avoidance and goal seeking.

The basic model has been extended in several different ways since Reynolds proposed it. For instance, Delgado-Mata et al. extended the basic model to incorporate the effects of fear. Olfaction was used to transmit emotion between animals, through pheromones modelled as particles in a free expansion gas. Hartman and Benes introduced a complementary force to the alignment that they call the change of leadership. This steer defines the chance of the boid to become a leader and try to escape.

The movement of Boids can be characterized as either chaotic (splitting groups and wild behaviour) or orderly. Unexpected behaviours, such as splitting flocks and reuniting after avoiding obstacles, can be considered emergent.

The boids framework is often used in computer graphics, providing realistic-looking representations of flocks of birds and other creatures, such as schools of fish or herds of animals. It was for instance used in the 1998 video game Half-Life for the flying bird-like creatures seen at the end of the game on Xen, named "boid" in the game files.

The Boids model can be used for direct control and stabilization of teams of simple Unmanned Ground Vehicles (UGV) or Micro Aerial Vehicles (MAV) in swarm robotics. For stabilization of heterogeneous UAV-UGV teams, the model was adapted for using onboard relative localization by Saska et al.

At the time of proposal, Reynolds' approach represented a giant step forward compared to the traditional techniques used in computer animation for motion pictures. The first animation created with the model was Stanley and Stella in: Breaking the Ice (1987), followed by a feature film debut in Tim Burton's film Batman Returns (1992) with computer generated bat swarms and armies of penguins marching through the streets of Gotham City.

The boids model has been used for other interesting applications. It has been applied to automatically program Internet multi-channel radio stations. It has also been used for visualizing information and for optimization tasks.

🔗 Physics 🔗 Greece 🔗 Food and drink 🔗 Spirits

The ouzo effect (also louche effect and spontaneous emulsification) is a milky (louche) oil-in-water emulsion that is formed when water is added to ouzo and other anise-flavored liqueurs and spirits, such as pastis, rakı, arak, sambuca and absinthe. Such emulsions occur with only minimal mixing and are highly stable.

🔗 Psychology 🔗 Education 🔗 Classical music

The Mozart effect is the theory that listening to the music of Mozart may temporarily boost scores on one portion of an IQ test. Popular science versions of the theory make the claim that "listening to Mozart makes you smarter" or that early childhood exposure to classical music has a beneficial effect on mental development.

The original study from 1993 reported a short-term (lasting about 15 minutes) improvement on the performance of certain kinds of mental tasks known as spatial reasoning, such as folding paper and solving mazes. The results were highly exaggerated by the popular press and became "Mozart makes you smart", which was said to apply to children in particular (the original study included 36 college students). These claims led to a commercial fad with Mozart CDs being sold to parents, the U.S. state of Georgia even proposed a budget to provide every child with a CD of classical music.

A meta-analysis of studies that have replicated the original study shows that there is little evidence that listening to Mozart has any particular effect on spatial reasoning. The author of the original study has stressed that listening to Mozart has no effect on general intelligence.

🔗 Military history 🔗 China 🔗 Urban studies and planning 🔗 Military history/Fortifications 🔗 Military history/Asian military history 🔗 Hong Kong 🔗 Military history/Chinese military history 🔗 Organized crime

Kowloon Walled City was an ungoverned, densely populated settlement in Kowloon City, Hong Kong. Originally a Chinese military fort, the Walled City became an enclave after the New Territories were leased to the UK by China in 1898. Its population increased dramatically following the Japanese occupation of Hong Kong during World War II. By 1990, the walled city contained 50,000 residents within its 2.6-hectare (6.4-acre) borders. From the 1950s to the 1970s, it was controlled by local triads and had high rates of prostitution, gambling, and drug abuse.

In January 1987, the Hong Kong municipal government announced plans to demolish the walled city. After an arduous eviction process, demolition began in March 1993 and was completed in April 1994. Kowloon Walled City Park opened in December 1995 and occupies the area of the former Walled City. Some historical artefacts from the walled city, including its yamen building and remnants of its southern gate, have been preserved there.

🔗 Aviation 🔗 Disaster management 🔗 Aviation/Aviation accident 🔗 Canada 🔗 Aviation/aircraft 🔗 Aviation/gliding 🔗 Canada/History of Canada 🔗 Canada/Manitoba

Air Canada Flight 143 was a Canadian scheduled domestic passenger flight between Montreal and Edmonton that ran out of fuel on July 23, 1983, at an altitude of 41,000 feet (12,000 m), midway through the flight. The crew was able to glide the Boeing 767 aircraft safely to an emergency landing at a former Royal Canadian Air Force base in Gimli, Manitoba, that had been turned into a motor racing track. This unusual aviation incident earned the aircraft the nickname "Gimli Glider".

The subsequent investigation revealed that a combination of company failures, human errors and confusion over unit measures had led to the aircraft being refuelled with insufficient fuel for the planned flight.

🔗 Library of Congress 🔗 Classical music 🔗 Albums

In C is a musical piece composed by Terry Riley in 1964 for an indefinite number of performers. He suggests "a group of about 35 is desired if possible but smaller or larger groups will work". A series of short melodic fragments that can be repeated at the discretion of musicians, In C is often cited as the first minimalist composition to make a significant impact on the public consciousness.

The piece was first performed by Steve Reich, Jon Gibson, Pauline Oliveros, Stuart Dempster, Morton Subotnick and others at the San Francisco Tape Music Center. It received its first recorded release in 1968 on CBS Records. Subsequent performances have been recorded many times since.

In 2022, the 1968 LP recording of In C was selected by the Library of Congress for preservation in the United States National Recording Registry as being "culturally, historically, or aesthetically significant.".

🔗 Lists 🔗 Statistics 🔗 Linguistics 🔗 Linguistics/Applied Linguistics 🔗 Languages 🔗 Countries 🔗 English Language

The following is a list of English-speaking population by country, including information on both native speakers and second-language speakers.

Some of the entries in this list are dependent territories (e.g.: U.S. Virgin Islands), autonomous regions (e.g.: Hong Kong) or associated states (e.g.: Cook Islands) of other countries, rather than being fully sovereign countries in their own right.

🔗 Physics

Absolute hot is a theoretical upper limit to the thermodynamic temperature scale, conceived as an opposite to absolute zero.

🔗 Computing 🔗 Computing/Software

SIMH is a free and open source, multi-platform multi-system emulator. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, and has been in development in one form or another since the 1960s.

🔗 Chemistry

Supramolecular chemistry refers to the branch of chemistry concerning chemical systems composed of a discrete number of molecules. The strength of the forces responsible for spatial organization of the system range from weak intermolecular forces, electrostatic charge, or hydrogen bonding to strong covalent bonding, provided that the electronic coupling strength remains small relative to the energy parameters of the component. While traditional chemistry concentrates on the covalent bond, supramolecular chemistry examines the weaker and reversible non-covalent interactions between molecules. These forces include hydrogen bonding, metal coordination, hydrophobic forces, van der Waals forces, pi–pi interactions and electrostatic effects.

Important concepts advanced by supramolecular chemistry include molecular self-assembly, molecular folding, molecular recognition, host–guest chemistry, mechanically-interlocked molecular architectures, and dynamic covalent chemistry. The study of non-covalent interactions is crucial to understanding many biological processes that rely on these forces for structure and function. Biological systems are often the inspiration for supramolecular research.