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The (pan)arthropod head problem is a long-standing zoological dispute concerning the segmental composition of the heads of the various arthropod groups, and how they are evolutionarily related to each other. While the dispute has historically centered on the exact make-up of the insect head, it has been widened to include other living arthropods such as chelicerates, myriapods, crustaceans; and fossil forms, such as the many arthropods known from exceptionally preserved Cambrian faunas. While the topic has classically been based on insect embryology, in recent years a great deal of developmental molecular data has become available. Dozens of more or less distinct solutions to the problem, dating back to at least 1897, have been published, including several in the 2000s.

The arthropod head problem is popularly known as the endless dispute, the title of a famous paper on the subject by Jacob G. Rempel in 1975, referring to its seemingly intractable nature. Although some progress has been made since that time, the precise nature of especially the labrum and the pre-oral region of arthropods remain highly controversial.

The Cybernetic Culture Research Unit (CCRU) was an experimental cultural theorist collective formed in late 1995 at Warwick University, England and gradually separated from academia until it dissolved in 2003. It garnered reputation for its idiosyncratic and surreal "theory-fiction" which incorporated cyberpunk and Gothic horror, and its work has since had an online cult following related to the rise in popularity of accelerationism. Warwick University maintains that the CCRU was never a sanctioned academic project, with some faculty going so far as to assert that the CCRU "has never existed". The CCRU are strongly associated with their former leading members, Sadie Plant, Mark Fisher and Nick Land.

The ocean temperature varies by depth, geographical location and season. Both the temperature and salinity of ocean water differs. Warm surface water is generally saltier than the cooler deep or polar waters; in polar regions, the upper layers of ocean water are cold and fresh. Deep ocean water is cold, salty water found deep below the surface of Earth's oceans. This water has a very uniform temperature, around 0-3 °C. The ocean temperature also depends on the amount of solar radiation falling on its surface. In the tropics, with the Sun nearly overhead, the temperature of the surface layers can rise to over 30 °C (86 °F) while near the poles the temperature in equilibrium with the sea ice is about −2 °C (28 °F). There is a continuous circulation of water in the oceans. Thermohaline circulation (THC) is a part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes. Warm surface currents cool as they move away from the tropics, and the water becomes denser and sinks. The cold water moves back towards the equator as a deep sea current, driven by changes in the temperature and density of the water, before eventually welling up again towards the surface.

Ocean temperature as a term is used either for the temperature in the ocean at any depth, or specifically for the ocean temperatures that are not near the surface (in which case it is synonymous with "deep ocean temperature").

It is clear that the oceans are warming as a result of climate change and this rate of warming is increasing.^: 9 The upper ocean (above 700 m) is warming fastest, but the warming trend extends throughout the ocean. In 2022, the global ocean was the hottest ever recorded by humans.

The Caproni Ca.60 Transaereo, often referred to as the Noviplano (nine-wing) or Capronissimo, was the prototype of a large nine-wing flying boat intended to become a 100-passenger transatlantic airliner. It featured eight engines and three sets of triple wings.

Only one example of this aircraft, designed by Italian aviation pioneer Gianni Caproni, was built by the Caproni company. It was tested on Lake Maggiore in 1921: its brief maiden flight took place on February 12 or March 2. Its second flight was March 4; shortly after takeoff, the aircraft crashed on the water surface and broke up upon impact. The Ca.60 was further damaged when the wreck was towed to shore and, in spite of Caproni's intention to rebuild the aircraft, the project was soon abandoned because of its excessive cost. The few surviving parts are on display at the Gianni Caproni Museum of Aeronautics and at the Volandia aviation museum in Italy.

The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar.

In 1983, David H. D. Warren designed an abstract machine for the execution of Prolog consisting of a memory architecture and an instruction set. This design became known as the Warren Abstract Machine (WAM) and has become the de facto standard target for Prolog compilers.

The Two Cultures is the first part of an influential 1959 Rede Lecture by British scientist and novelist C. P. Snow which were published in book form as The Two Cultures and the Scientific Revolution the same year. Its thesis was that science and the humanities which represented "the intellectual life of the whole of western society" had become split into "two cultures" and that this division was a major handicap to both in solving the world's problems.

A Hobson's choice is a free choice in which only one thing is actually offered. The term is often used to describe an illusion that multiple choices are available. The most well known Hobson's choice is "I'll give you a choice: take it or leave it", wherein "leaving it" is strongly undesirable.

The phrase is said to have originated with Thomas Hobson (1544–1631), a livery stable owner in Cambridge, England, who offered customers the choice of either taking the horse in his stall nearest to the door or taking none at all.

A self-replicating machine is a type of autonomous robot that is capable of reproducing itself autonomously using raw materials found in the environment, thus exhibiting self-replication in a way analogous to that found in nature. The concept of self-replicating machines has been advanced and examined by Homer Jacobson, Edward F. Moore, Freeman Dyson, John von Neumann, Konrad Zuse and in more recent times by K. Eric Drexler in his book on nanotechnology, Engines of Creation (coining the term clanking replicator for such machines) and by Robert Freitas and Ralph Merkle in their review Kinematic Self-Replicating Machines which provided the first comprehensive analysis of the entire replicator design space. The future development of such technology is an integral part of several plans involving the mining of moons and asteroid belts for ore and other materials, the creation of lunar factories, and even the construction of solar power satellites in space. The von Neumann probe is one theoretical example of such a machine. Von Neumann also worked on what he called the universal constructor, a self-replicating machine that would be able to evolve and which he formalized in a cellular automata environment. Notably, Von Neumann's Self-Reproducing Automata scheme posited that open-ended evolution requires inherited information to be copied and passed to offspring separately from the self-replicating machine, an insight that preceded the discovery of the structure of the DNA molecule by Watson and Crick and how it is separately translated and replicated in the cell.

A self-replicating machine is an artificial self-replicating system that relies on conventional large-scale technology and automation. Although suggested earlier than in the late 1940's by Von Neumann, no self-replicating machine has been seen until today. Certain idiosyncratic terms are occasionally found in the literature. For example, the term clanking replicator was once used by Drexler to distinguish macroscale replicating systems from the microscopic nanorobots or "assemblers" that nanotechnology may make possible, but the term is informal and is rarely used by others in popular or technical discussions. Replicators have also been called "von Neumann machines" after John von Neumann, who first rigorously studied the idea. However, the term "von Neumann machine" is less specific and also refers to a completely unrelated computer architecture that von Neumann proposed and so its use is discouraged where accuracy is important. Von Neumann himself used the term universal constructor to describe such self-replicating machines.

Historians of machine tools, even before the numerical control era, sometimes figuratively said that machine tools were a unique class of machines because they have the ability to "reproduce themselves" by copying all of their parts. Implicit in these discussions is that a human would direct the cutting processes (later planning and programming the machines), and would then assemble the parts. The same is true for RepRaps, which are another class of machines sometimes mentioned in reference to such non-autonomous "self-replication". In contrast, machines that are truly autonomously self-replicating (like biological machines) are the main subject discussed here.

A long-running debate in computer science known as the Protocol Wars occurred from the 1970s to the 1990s when engineers, organizations and nations became polarized over the issue of which communication protocol would result in the best and most robust computer networks. This culminated in the Internet–OSI Standards War in the late 1980s and early 1990s, which was ultimately "won" by the Internet protocol suite ("TCP/IP") by the mid-1990s and has since resulted in most other protocols disappearing.

The pioneers of packet switching technology built computer networks to research data communications in the early 1970s. As public data networks emerged in the mid to late 1970s, the debate about interface standards was described as a "battle for access standards". An international collaboration between several national postal, telegraph and telephone ("PTT") providers and commercial operators developed the X.25 standard in 1976, which was adopted on public networks providing global coverage. Several proprietary standards also emerged, most notably IBM's Systems Network Architecture.

The United States Department of Defense developed and tested TCP/IP during the 1970s in collaboration with universities and researchers in the United States, United Kingdom and France. IPv4 was released in 1981 and the DoD made it standard for all military computer networking. By 1984, an international reference model known as the OSI model had been agreed on, with which TCP/IP was not compatible. Many governments in Europe – particularly France, West Germany, the United Kingdom and the European Economic Community – and also the United States Department of Commerce mandated compliance with the OSI model and the US Department of Defense planned to transition away from TCP/IP to OSI.

Meanwhile, the development of a complete Internet protocol suite by 1989, and partnerships with the telecommunication and computer industry to incorporate TCP/IP software into various operating systems laid the foundation for the widespread adoption of TCP/IP as a comprehensive protocol suite. While OSI developed its networking standards in the late 1980s, TCP/IP came into widespread use on multi-vendor networks for internetworking and as the core component of the emerging Internet.