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The Ford Nucleon is a concept car developed by Ford in 1957 designed as a future nuclear-powered car, one of a handful of such designs during the 1950s and '60s. The concept was only demonstrated as a scale model. The design did not include an internal-combustion engine; rather, the vehicle was to be powered by a small nuclear reactor in the rear of the vehicle, based on the assumption that this would one day be possible by reducing sizes. The car was to use a steam engine powered by uranium fission similar to those found in nuclear submarines.

The mock-up of the car can be viewed at the Henry Ford Museum in Dearborn, Michigan.

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.

In graph theory, a moral graph is used to find the equivalent undirected form of a directed acyclic graph. It is a key step of the junction tree algorithm, used in belief propagation on graphical models.

The moralized counterpart of a directed acyclic graph is formed by adding edges between all pairs of non-adjacent nodes that have a common child, and then making all edges in the graph undirected. Equivalently, a moral graph of a directed acyclic graph G is an undirected graph in which each node of the original G is now connected to its Markov blanket. The name stems from the fact that, in a moral graph, two nodes that have a common child are required to be married by sharing an edge.

Moralization may also be applied to mixed graphs, called in this context "chain graphs". In a chain graph, a connected component of the undirected subgraph is called a chain. Moralization adds an undirected edge between any two vertices that both have outgoing edges to the same chain, and then forgets the orientation of the directed edges of the graph.

Since the Renaissance, every century has seen the solution of more mathematical problems than the century before, yet many mathematical problems, both major and minor, still remain unsolved. These unsolved problems occur in multiple domains, including physics, computer science, algebra, analysis, combinatorics, algebraic, differential, discrete and Euclidean geometries, graph, group, model, number, set and Ramsey theories, dynamical systems, partial differential equations, and more. Some problems may belong to more than one discipline of mathematics and be studied using techniques from different areas. Prizes are often awarded for the solution to a long-standing problem, and lists of unsolved problems (such as the list of Millennium Prize Problems) receive considerable attention.

In quantum field theory, the Casimir effect and the Casimir–Polder force are physical forces arising from a quantized field. They are named after the Dutch physicist Hendrik Casimir who predicted them in 1948.

The Casimir effect can be understood by the idea that the presence of conducting metals and dielectrics alters the vacuum expectation value of the energy of the second quantized electromagnetic field. Since the value of this energy depends on the shapes and positions of the conductors and dielectrics, the Casimir effect manifests itself as a force between such objects.

Any medium supporting oscillations has an analogue of the Casimir effect. For example, beads on a string as well as plates submerged in turbulent water or gas illustrate the Casimir force.

In modern theoretical physics, the Casimir effect plays an important role in the chiral bag model of the nucleon; in applied physics it is significant in some aspects of emerging microtechnologies and nanotechnologies.

A Michigan left is an at-grade intersection design that replaces each left turn at an intersection between a (major) divided roadway and a secondary (minor) roadway with the combination of a right turn followed by a U-turn, or a U-turn followed by a right turn, depending on the situation.

The Writers Guild of America (WGA) writing credit system for motion pictures and television programs covers all works under the jurisdiction of the Writers Guild of America, East (WGAE) and the Writers Guild of America, West (WGAW). Since 1941, the Screen Writers Guild and then the WGA has been the final arbiter of who receives credit for writing a theatrical, television or new media motion picture written under their jurisdiction. Though the system has been a standard since before the WGA's inception, it has seen criticism.

Sixel, short for "six pixels", is a bitmap graphics format supported by terminals and printers from DEC. It consists of a pattern six pixels high and one wide, resulting in 64 possible patterns. Each possible pattern is assigned an ASCII character, making the sixels easy to transmit on 7-bit serial links.

Sixel was first introduced as a way of sending bitmap graphics to DEC dot matrix printers like the LA50. After being put into "sixel mode" the following data was interpreted to directly control six of the pins in the nine-pin print head. A string of sixel characters encodes a single 6-pixel high row of the image.

The system was later re-used as a way to send bitmap data to the VT200 series and VT320 terminals when defining custom character sets. A series of sixels are used to transfer the bitmap for each character. This feature is known as soft character sets or dynamically redefinable character sets (DRCS). With the VT240, VT241, VT330, and VT340, the terminals could decode a complete sixel image to the screen, like those previously sent to printers.

Habitat is a massively multiplayer online role-playing game (MMORPG) developed by LucasArts. It is the first attempt at a large-scale commercial virtual community that was graphic based. Initially created in 1985 by Randy Farmer and Chip Morningstar, the game was made available as a beta test in 1986 by Quantum Link, an online service for the Commodore 64 computer and the corporate progenitor to AOL. Both Farmer and Morningstar were given a First Penguin Award at the 2001 Game Developers Choice Awards for their innovative work on Habitat. As a graphical MUD it is considered a forerunner of modern MMORPGs unlike other online communities of the time (i.e. MUDs and massively multiplayer onlines with text-based interfaces). Habitat had a GUI and large user base of consumer-oriented users, and those elements in particular have made Habitat a much-cited project and acknowledged benchmark for the design of today's online communities that incorporate accelerated 3D computer graphics and immersive elements into their environments.

A saddle chair uses the same principles in its design as an equestrian saddle. It is equipped with a chair base on casters and a gas cylinder for adjusting the correct sitting height. The casters enable moving around and reaching out for objects while sitting. Some saddle chairs have backrests, but most do not.

Riding-like sitting on a saddle chair differs from sitting on a conventional chair. Saddle chair users sit 20–30 cm higher, which puts the hips and the knees into a 135° angle, compared to the 90° angle typically associated with sitting on a traditional chair.

Because the saddle chair is higher than a normal office chair, the desk has to be higher as well. For this purpose there are desks that can be electronically or mechanically adjusted to fit the user. A saddle chair can also be used with a normal office desk, but then the desk has to be lifted up with height extension pieces.

The saddle chair seat is either solid or divided. A divided seat reduces pressure on the perineum and lowers the temperature in the genital area. A divided seat is thought to be healthier, especially for men, than a solid seat.

Some saddle chairs include not only height adjustments but also a tilt mechanism. There is also a divided saddle chair model on the market that has an adjustable gap between the two seat parts. Accessories, such as elbow and wrist supports, are available for saddle chairs to make different work tasks easier.

Adapting to a saddle chair takes time and requires a new kind of attitude towards sitting. The most common reason for using a saddle chair is that the users feel it is healthier for the back and legs than a standard chair. An intervention study on schoolchildren found that initially saddle chairs were liked better, but the difference leveled off over time.