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🔗 Internet 🔗 Computing

BBCode ("Bulletin Board Code") is a lightweight markup language used to format messages in many Internet forum software. It was first introduced in 1998. The available "tags" of BBCode are usually indicated by square brackets ([ and ]) surrounding a keyword, and are parsed before being translated into HTML.

🔗 Toys

The Gakken EX-System is a series of educational electronics kits produced by Gakken in the late 1970s. The kits use denshi blocks (also known as electronic blocks) to allow electronics experiments to be performed easily and safely. Over 25 years after its original release, one of the main kits from the series was reissued in Japan in 2002.

🔗 Systems 🔗 Systems/Control theory

In control theory, a bang–bang controller (2 step or on–off controller), also known as a hysteresis controller, is a feedback controller that switches abruptly between two states. These controllers may be realized in terms of any element that provides hysteresis. They are often used to control a plant that accepts a binary input, for example a furnace that is either completely on or completely off. Most common residential thermostats are bang–bang controllers. The Heaviside step function in its discrete form is an example of a bang–bang control signal. Due to the discontinuous control signal, systems that include bang–bang controllers are variable structure systems, and bang–bang controllers are thus variable structure controllers.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Military history/Medieval warfare

A rondel dagger or roundel dagger was a type of stiff-bladed dagger in Europe in the late Middle Ages (from the 14th century onwards), used by a variety of people from merchants to knights. It was worn at the waist and might be used as a utility tool, or worn into battle or in a jousting tournament as a side arm.

The rondel dagger featured a long, slim steel blade with a round or circular hand guard and pommel. Designed for close-quarter combat, it was effective in puncturing and bursting mail armor links and penetrating weak points in plate armor. The dagger evolved from the early knightly dagger and became the standard side-arm for knights in the 15th century. It was used as a backup weapon for hand-to-hand fighting and as a tool to force surrender, as captured knights could be ransomed. The rondel dagger also gained popularity among the middle class in the 15th century. Various combat techniques involving the rondel dagger can be found in Hans Talhoffer's combat manuals from the 1440s to 1460s.

🔗 Japan 🔗 Japan/Culture

Chindōgu (珍道具) is the practice of inventing ingenious everyday gadgets that seem to be ideal solutions to particular problems, but which may cause more problems than they solve. The term is of Japanese origin.

🔗 Disability 🔗 Deaf

Tadoma is a method of communication used by deafblind individuals, in which the deafblind person places their little finger on the speaker's lips and their fingers along the jawline. The middle three fingers often fall along the speaker's cheeks with the little finger picking up the vibrations of the speaker's throat. It is sometimes referred to as tactile lipreading, as the deafblind person feels the movement of the lips, as well as vibrations of the vocal cords, puffing of the cheeks and the warm air produced by nasal sounds such as 'N' and 'M'. There are variations in the hand positioning, and it is a method sometimes used by people to support their remaining hearing.

In some cases, especially if the speaker knows sign language, the deaf-blind person may use the Tadoma method with one hand, to feel the speaker's face, and, at the same time, the deaf-blind person may use their other hand to feel the speaker sign the same words. In this way, the two methods reinforce each other, giving the deaf-blind person a better chance of understanding what the speaker is trying to communicate.

In addition, the Tadoma method can provide the deaf-blind person with a closer connection with speech than they might otherwise have had. This can, in turn, help them to retain speech skills that they developed before going deaf, and in special cases, to learn how to speak brand new words.

It is a difficult method to learn and use, and is rarely used nowadays. However, a small number of deafblind people successfully use Tadoma in everyday communication.

🔗 India 🔗 Visual arts

Mauryan polish describes one of the frequent characteristics of architecture and sculptures of the Maurya Empire in India (325 to 185 BCE), which gives a very smooth and shiny surface to the stone material, generally of sandstone or granite. Mauryan polish is found especially in the Ashoka Pillars as well as in some constructions like the Barabar Caves. The technique did not end with the empire, but continued to be "used on occasion up to the first or second century A.D.", although the presence of the polish sometimes complicates dating, as with the Didarganj Yakshi. According to the archaeologist John Marshall: the "extraordinary precision and accuracy which characterizes all Mauryan works, and which has never, we venture to say, been surpassed even by the finest workmanship on Athenian buildings".

🔗 Apple Inc. 🔗 Software 🔗 Software/Computing

A/UX is a Unix-based operating system from Apple Computer for Macintosh computers, integrated with System 7's graphical interface and application compatibility. It is Apple's first official Unix-based operating system, launched in 1988 and discontinued in 1995 with version 3.1.1. A/UX requires select 68k-based Macintosh models with an FPU and a paged memory management unit (PMMU), including the Macintosh II, SE/30, Quadra, and Centris series.

Described by InfoWorld as "an open systems solution with the Macintosh at its heart", A/UX is based on UNIX System V Release 2.2, with features from System V Releases 3 and 4 and BSD versions 4.2 and 4.3. It is POSIX- and System V Interface Definition (SVID)-compliant and includes TCP/IP networking since version 2. Having a Unix-compatible, POSIX-compliant operating system enabled Apple to bid for large contracts to supply computers to U.S. federal government institutes.

🔗 History of Science 🔗 Tree of Life

The species problem is the set of questions that arises when biologists attempt to define what a species is. Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for sexually reproducing organisms such as birds is useless for species that reproduce asexually, such as bacteria. The scientific study of the species problem has been called microtaxonomy.

One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from reproductive isolation with no interbreeding, to panmixis, unlimited interbreeding. Populations can move forward or backwards along this continuum, at any point meeting the criteria for one or another species concept, and failing others.

Many of the debates on species touch on philosophical issues, such as nominalism and realism, and on issues of language and cognition.

The current meaning of the phrase "species problem" is quite different from what Charles Darwin and others meant by it during the 19th and early 20th centuries. For Darwin, the species problem was the question of how new species arose. Darwin was however one of the first people to question how well-defined species are, given that they constantly change.

🔗 Trains 🔗 Trains/Operations

Signalling block systems enable the safe and efficient operation of railways by preventing collisions between trains. The basic principle is that a route is broken up into a series of sections or "blocks". Only one train may occupy a block at a time, and the blocks are sized to allow a train to stop within them. That ensures that a train always has time to stop before getting dangerously close to another train on the same line. The block system is referred to in the UK as the method of working, in the US as the method of operation, and in Australia as safeworking.

In most situations, a system of signals is used to control the passage of trains between the blocks. When a train enters a block, signals at both ends change to indicate that the block is occupied, typically using red lamps or indicator flags. When a train first enters a block, the rear of the same train has not yet left the previous block, so both blocks are marked as occupied. That ensures there is slightly less than one block length on either end of the train that is marked as occupied, so any other train approaching that section will have enough room to stop in time, even if the first train has stopped dead on the tracks. The previously-occupied block will only be marked unoccupied when the end of the train has entirely left it, leaving the entire block clear.

Block systems have the disadvantage that they limit the number of trains on a particular route to something fewer than the number of blocks. Since the route has a fixed length, increasing the number of trains requires the creation of more blocks, which means the blocks are shorter and trains have to operate at lower speeds in order to stop safely. As a result, the number and size of blocks are closely related to the overall route capacity, and cannot be changed easily because expensive alterations to the signals along the line would be required.

Block systems are used to control trains between stations and yards, but not normally within the yards, where some other method is used. Any block system is defined by its associated physical equipment and by the application of a relevant set of rules. Some systems involve the use of signals while others do not. Some systems are specifically designed for single track railways, on which there is a danger of both head-on and rear-end collision, as opposed to double track, on which the main danger is rear-end collisions.