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π Ocean Temperature
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 0-3Β Β°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 30Β Β°C (86Β Β°F) while near the poles the temperature in equilibrium with the sea ice is about β2Β Β°C (28Β Β°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.:β9β 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.
Discussed on
- "Ocean Temperature" | 2023-05-13 | 87 Upvotes 53 Comments
π Pax Calendar
The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar.
Discussed on
- "Pax Calendar" | 2023-05-12 | 48 Upvotes 24 Comments
π Hobson's Choice
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 (1544β1631), 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.
Discussed on
- "Hobson's Choice" | 2023-05-11 | 91 Upvotes 38 Comments
π Protocol Wars
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 InternetβOSI 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 β particularly France, West Germany, the United Kingdom and the European Economic Community β 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.
Discussed on
- "Protocol Wars" | 2023-05-10 | 183 Upvotes 116 Comments
π Self-Replicating Machine
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.
π Darvaza Gas Crater
The Darvaza gas crater (Turkmen: Garagum Γ½alkymy), also known as the Door to Hell or Gates of Hell, or, officially, the Shining of Karakum, is a burning natural gas field collapsed into a cavern near Darvaza, Turkmenistan. The floor and especially rim of the crater is illumined by hundreds of natural gas fires. The crater has been burning for an unknown amount of time, as how the crater formed and ignited remains unknown.
Discussed on
- "Darvaza Gas Crater" | 2023-05-09 | 109 Upvotes 24 Comments
π Indian Citizenship Act of 1924
The Indian Citizenship Act of 1924, (43Β Stat.Β 253, enacted June 2, 1924) was an Act of the United States Congress that granted US citizenship to the indigenous peoples of the United States. While the Fourteenth Amendment to the United States Constitution defines a citizen as any persons born in the United States and subject to its laws and jurisdiction, the amendment had previously been interpreted by the courts not to apply to Native peoples.
The act was proposed by Representative Homer P. Snyder (R-NY), and signed into law by President Calvin Coolidge on June 2, 1924. It was enacted partially in recognition of the thousands of Native Americans who served in the armed forces during the First World War.
Discussed on
- "Indian Citizenship Act of 1924" | 2023-05-07 | 30 Upvotes 12 Comments
π Defenestrations of Prague
The Defenestrations of Prague (Czech: PraΕΎskΓ‘ defenestrace, German: Prager Fenstersturz, Latin: Defenestratio Pragensis) were three incidents in the history of Bohemia in which people were defenestrated (thrown out of a window). Though already existing in Middle French, the word defenestrate ("out of the window") is believed to have first been used in English in reference to the episodes in Prague in 1618 when the disgruntled Protestant estates threw two royal governors and their secretary out of a window of the HradΔany Castle and wrote an extensive apologia explaining their action. In the Middle Ages and early modern times, defenestration was not uncommonβthe act carried elements of lynching and mob violence in the form of murder committed together.
The first governmental defenestration occurred in 1419, the second in 1483 and the third in 1618, although the term "Defenestration of Prague" more commonly refers to the third. Often, however, the 1483 event is not recognized as a "significant defenestration", which leads to some ambiguity when the 1618 defenestration is referred to as the "second Prague defenestration". The first and third defenestrations helped to trigger a prolonged religious conflict inside Bohemia (the Hussite Wars, 1st defenestration) or beyond (Thirty Years' War, 3rd defenestration), while the second helped establish a religious peace in the country for 31 years (Peace of KutnΓ‘ Hora, 2nd defenestration).
Discussed on
- "Defenestrations of Prague" | 2023-05-08 | 35 Upvotes 35 Comments
π Operation Epsilon
Operation Epsilon was the codename of a program in which Allied forces near the end of World War II detained ten German scientists who were thought to have worked on Nazi Germany's nuclear program. The scientists were captured between May 1 and June 30, 1945, as part of the Allied Alsos Mission, mainly as part of its Operation Big sweep through southwestern Germany.
They were interned at Farm Hall, a bugged house in Godmanchester, near Cambridge, England, from July 3, 1945, to January 3, 1946. The primary goal of the program was to determine how close Nazi Germany had been to constructing an atomic bomb by listening to their conversations.
Discussed on
- "Operation Epsilon" | 2023-05-08 | 61 Upvotes 10 Comments
π Intel Skulltrail
Intel's Skulltrail is an enthusiast gaming platform that was released on February 19, 2008. It is based on the company's 5400 "Seaburg" workstation chipset. The primary difference between Skulltrail and Intel's current and past enthusiast chipsets is a dual CPU socket design that allows two processors to operate on the same motherboard. Therefore, Skulltrail can operate eight processing cores on one system. The platform supports two Core 2 Extreme QX9775 processors (commonly mistaken for the Core 2 Extreme QX9770, which is the LGA775 counterpart), which operate at 3.2Β GHz.
Skulltrail was one of the first platforms to support SLI on chipsets not designed by Nvidia. It achieves this by including two NVIDIA nForce 100 PCIe 1.1 switch (two x16 to one x16) chips. The implementation of SLI supports Quad SLI technology, which is achieved through the use of two dual-GPU graphics cards from NVIDIA, including the GeForce 9800 GX2. This gives a total of four graphics processors. Owners of Skulltrail systems can also make use of up to four ATI graphics cards using ATI CrossFireX technology, which made SkullTrail the only platform (other than Intel X58 and P55 Chipset) to support both SLI and CrossFire with public drivers at the time of release. The HP Firebird 803 also supported SLI on one (proprietary, MXM) motherboard at the time, but the drivers were special and only available for Firebird hardware.
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- "Intel Skulltrail" | 2023-05-08 | 13 Upvotes 13 Comments