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The elephant clock was a medieval invention by Al-Jazari (1136–1206), an Arab engineer and inventor of various clocks. The device consisted of a weight powered water clock in the form of an Asian elephant. This horological technology was derived from earlier Indian clocks and Chinese clocks.

In China clock escapement mechanism was invented by the polymath and Buddhist monk Yi Xing as well as the hydraulic powered waterwheel and water clock in the mechanically-driven and rotated equatorial armillary sphere of the polymaths Zhang Heng and Ma Jun. The Elephant clock had some design differences compared to earlier Indian and Chinese clocks and the various elements of the clock are in the housing (howdah) on top of the elephant.

Al-Jazari upon finishing the development and construction of his Elephant clock wrote: "The elephant represents the Indian and African cultures, the two dragons represents Chinese culture, the phoenix represents Persian culture, the water work represents Greek culture, and the turban represents Islamic culture" signifying the multicultural mentality of the intellectual Al-Jazari.

In addition to its mechanical innovations, the clock itself is seen as an early example of multiculturalism represented in technology.

Slow-scan television (SSTV) is a picture transmission method, used mainly by amateur radio operators, to transmit and receive static pictures via radio in monochrome or color.

A literal term for SSTV is narrowband television. Analog broadcast television requires at least 6 MHz wide channels, because it transmits 25 or 30 picture frames per second (see ITU analog broadcast standards), but SSTV usually only takes up to a maximum of 3 kHz of bandwidth. It is a much slower method of still picture transmission, usually taking from about eight seconds to a couple of minutes, depending on the mode used, to transmit one image frame.

Since SSTV systems operate on voice frequencies, amateurs use it on shortwave (also known as HF by amateur radio operators), VHF and UHF radio.

The M44 cyanide device (also called a cyanide gun or cyanide trap) is used for the killing of coyotes, feral dogs, and foxes. It is made from four parts: a capsule holder wrapped with cloth or other soft material, a small plastic capsule containing 0.88 grams of sodium cyanide, a spring-powered ejector, and a 5-7 inch stake. To install the trap, the stake is first driven down into the ground, and then the capsule is put in the holder, screwed onto the cocked ejector, and secured to the stake. The wrapped capsule holder is smeared with scented bait to attract coyotes and make them bite and pull on it. (The use of a bite-and-pull action makes the trap less likely to be set off by non-canine wildlife.) When the trap is triggered, the spring propels a dose of sodium cyanide into the animals's mouth, and the sodium cyanide combines with water in the mouth to produce poisonous cyanide gas. In addition to the cyanide, the capsule contains Day-Glo fluorescent particle marker (orange in capsules used by the Wildlife Services, and yellow in capsules prepared for other users).

PGPfone was a secure voice telephony system developed by Philip Zimmermann in 1995. The PGPfone protocol had little in common with Zimmermann's popular PGP email encryption package, except for the use of the name. It used ephemeral Diffie-Hellman protocol to establish a session key, which was then used to encrypt the stream of voice packets. The two parties compared a short authentication string to detect a Man-in-the-middle attack, which is the most common method of wiretapping secure phones of this type. PGPfone could be used point-to-point (with two modems) over the public switched telephone network, or over the Internet as an early Voice over IP system.

In 1996, there were no protocol standards for Voice over IP. Ten years later, Zimmermann released the successor to PGPfone, Zfone and ZRTP, a newer and secure VoIP protocol based on modern VoIP standards. Zfone builds on the ideas of PGPfone.

According to the MIT PGPfone web page, "MIT is no longer distributing PGPfone. Given that the software has not been maintained since 1997, we doubt it would run on most modern systems."

The Trautonium is an electronic synthesizer invented in 1930 by Friedrich Trautwein in Berlin at the Musikhochschule's music and radio lab, the Rundfunkversuchstelle. Soon afterwards Oskar Sala joined him, continuing development until Sala's death in 2002.

The following is a list of the most expensive video games ever developed, with a minimum total cost of US$50 million and sorted by the total cost adjusted for inflation. Most game budgets are not disclosed, so this list is not indicative of industry trends.

Foldering is the practice of communicating via messages saved to the "drafts" folder of an email or other electronic messaging account that is accessible by multiple people. The messages are never actually sent.

Foldering has been described as a digital equivalent of a dead drop.

MOLLE (pronounced , similar in pronunciation to the name Molly) is an acronym for Modular Lightweight Load-carrying Equipment. It is used to define the current generation of load-bearing equipment and backpacks used by a number of NATO armed forces, especially the British Army and the United States Army.

The system's modularity is derived from the use of Pouch Attachment Ladder System (PALS) webbing equipment as rows of heavy-duty nylon stitched onto the vest to allow for the attachment of various compatible pouches and accessories. This method of attachment has become a de facto standard for modular tactical gear, replacing the All-purpose Lightweight Individual Carrying Equipment (ALICE) system used in the earliest modular vest systems (which is still in use with many police forces).

Dimetrodon ( (listen) or , meaning "two measures of teeth") is an extinct genus of non-mammalian synapsids that lived during the Cisuralian (Early Permian), around 295–272 million years ago (Ma). It is a member of the family Sphenacodontidae. The most prominent feature of Dimetrodon is the large neural spine sail on its back formed by elongated spines extending from the vertebrae. It walked on four legs and had a tall, curved skull with large teeth of different sizes set along the jaws. Most fossils have been found in the southwestern United States, the majority coming from a geological deposit called the Red Beds of Texas and Oklahoma. More recently, fossils have been found in Germany. Over a dozen species have been named since the genus was first described in 1878.

Dimetrodon is often mistaken for a dinosaur or as a contemporary of dinosaurs in popular culture, but it became extinct some 40 million years before the first appearance of dinosaurs. Reptile-like in appearance and physiology, Dimetrodon is nevertheless more closely related to mammals than to modern reptiles, though it is not a direct ancestor of mammals. Dimetrodon is assigned to the "non-mammalian synapsids", a group traditionally called "mammal-like reptiles". This groups Dimetrodon together with mammals in a clade (evolutionary group) called Synapsida, while placing dinosaurs, reptiles and birds in a separate clade, Sauropsida. Single openings in the skull behind each eye, known as temporal fenestrae, and other skull features distinguish Dimetrodon and mammals from most of the earliest sauropsids.

Dimetrodon was probably one of the apex predators of the Cisuralian ecosystems, feeding on fish and tetrapods, including reptiles and amphibians. Smaller Dimetrodon species may have had different ecological roles. The sail of Dimetrodon may have been used to stabilize its spine or to heat and cool its body as a form of thermoregulation. Some recent studies argue that the sail would have been ineffective at removing heat from the body due to large species being discovered with small sails and small species being discovered with large sails, essentially ruling out heat regulation as its main purpose. The sail was most likely used in courtship display with methods such as threatening rivals or showing off to potential mates.

The Montessori method of education is a type of educational method that involves children's natural interests and activities rather than formal teaching methods. A Montessori classroom places an emphasis on hands-on learning and developing real-world skills. It emphasizes independence and it views children as naturally eager for knowledge and capable of initiating learning in a sufficiently supportive and well-prepared learning environment. It discourages some conventional measures of achievement, such as grades and tests.

The method was started in the early 20th century by Italian physician Maria Montessori, who developed her theories through scientific experimentation with her students; the method has since been used in many parts of the world, in public and private schools alike.

A range of practices exist under the name "Montessori", which is not trademarked. Popular elements include mixed-age classrooms, student freedom (including their choices of activity), long blocks of uninterrupted work time, specially trained teachers and prepared environment. Scientific studies regarding the Montessori method are mostly positive, with a 2017 review stating that "broad evidence" exists for its efficacy.