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🔗 Technology 🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Maritime warfare

Communication with submarines is a field within military communications that presents technical challenges and requires specialized technology. Because radio waves do not travel well through good electrical conductors like salt water, submerged submarines are cut off from radio communication with their command authorities at ordinary radio frequencies. Submarines can surface and raise an antenna above the sea level, then use ordinary radio transmissions, however this makes them vulnerable to detection by anti-submarine warfare forces. Early submarines during World War II mostly traveled on the surface because of their limited underwater speed and endurance; they dove mainly to evade immediate threats. During the Cold War, however, nuclear-powered submarines were developed that could stay submerged for months. Transmitting messages to these submarines is an active area of research. Very low frequency (VLF) radio waves can penetrate seawater a few hundred feet, and many navies use powerful VLF transmitters for submarine communications. A few nations have built transmitters which use extremely low frequency (ELF) radio waves, which can penetrate seawater to reach submarines at operating depths, but these require huge antennas. Other techniques that have been used include sonar and blue lasers.

🔗 Military history 🔗 Military history/World War II 🔗 Scottish Islands

Operation Vegetarian was a British military plan in 1942 to disseminate linseed cakes infected with anthrax spores onto the fields of Germany. These cakes would have been eaten by the cattle, which would then be consumed by the civilian population, causing the deaths of millions of German citizens. Furthermore, it would have wiped out the majority of Germany's cattle, creating a massive food shortage for the rest of the population that remained uninfected. Preparations were not complete until early 1944. Operation Vegetarian was only to be used in the event of a German anthrax attack on the United Kingdom.

The cakes themselves were tested on Gruinard Island, just off the coast of Scotland. Because of the widespread contamination from the anthrax spores, the land remained quarantined until 1990. The five million cakes made to be disseminated in Germany were eventually destroyed in an incinerator shortly after the end of World War II.

In his novel The Impossible Dead (2011), author Ian Rankin mentions the clandestine events surrounding the removal of contaminated soils from Guinard Island by a protest group, the Dark Harvest Commando, and the island's removal from maps by the British Government. The island also features as the principal setting for the 1985 novel El año de gracia, by Cristina Fernández Cubas, in which the protagonist spends a winter shipwrecked on the island.

In decision theory, the sure-thing principle states that a decision maker who would take a certain action if he knew that event E has occurred, and also if he knew that the negation of E has occurred, should also take that same action if he knows nothing about E.

The principle was coined by L.J. Savage:

A businessman contemplates buying a certain piece of property. He considers the outcome of the next presidential election relevant. So, to clarify the matter to himself, he asks whether he would buy if he knew that the Democratic candidate were going to win, and decides that he would. Similarly, he considers whether he would buy if he knew that the Republican candidate were going to win, and again finds that he would. Seeing that he would buy in either event, he decides that he should buy, even though he does not know which event obtains, or will obtain, as we would ordinarily say. It is all too seldom that a decision can be arrived at on the basis of this principle, but except possibly for the assumption of simple ordering, I know of no other extralogical principle governing decisions that finds such ready acceptance.

He formulated the principle as a dominance principle, but it can also be framed probabilistically. Richard Jeffrey and later Judea Pearl showed that Savage's principle is only valid when the probability of the event considered (e.g., the winner of the election) is unaffected by the action (buying the property). Under such conditions, the sure-thing principle is a theorem in the do-calculus (see Bayes networks). Blyth constructed a counterexample to the sure-thing principle using sequential sampling in the context of Simpson's paradox, but this example violates the required action-independence provision.

The principle is closely related to independence of irrelevant alternatives, and equivalent under the axiom of truth (everything the agent knows is true). It is similarly targeted by the Ellsberg and Allais paradoxes, in which actual people's choices seem to violate this principle.

🔗 Internet 🔗 Internet culture 🔗 Business 🔗 Politics 🔗 Sociology

The Streisand effect is a social phenomenon that occurs when an attempt to hide, remove, or censor information has the unintended consequence of further publicizing that information, often via the Internet. It is named after American entertainer Barbra Streisand, whose attempt to suppress photographs of her residence in Malibu, California inadvertently drew further attention to it in 2003.

Attempts to suppress information are often made through cease-and-desist letters, but instead of being suppressed, the information receives extensive publicity, as well as media extensions such as videos and spoof songs, which can be mirrored on the Internet or distributed on file-sharing networks.

The Streisand effect is an example of psychological reactance, wherein once people are aware that some information is being kept from them, they are significantly more motivated to access and spread that information.

🔗 Physics 🔗 Physics/Fluid Dynamics

A jiggle syphon (or siphon) is the combination of a syphon pipe and a simple priming pump that uses mechanical shaking action to pump enough liquid up the pipe to reach the highest point, and thus start the syphoning action.

In 2011, Randall Munroe in his comic xkcd coined the term "citogenesis" to describe the creation of "reliable" sources through circular reporting. This is a list of some well-documented cases where Wikipedia has been the source.

🔗 United States 🔗 Alternative Views

The Business Plot was a political conspiracy in 1933 in the United States. Retired Marine Corps Major General Smedley Butler revealed that wealthy businessmen were plotting to create a fascist veterans' organization with Butler as its leader and use it in a coup d'état to overthrow President Franklin D. Roosevelt. In 1934, Butler testified before the United States House of Representatives Special Committee on Un-American Activities (the "McCormack–Dickstein Committee") on these revelations. No one was prosecuted.

At the time of the incidents, news media dismissed the plot, with a New York Times editorial characterizing it as a "gigantic hoax". While historians have not accepted the notion of a plot, they agree that Butler described one.

🔗 Architecture

Ruin value (German: Ruinenwert) is the concept that a building be designed such that if it eventually collapsed, it would leave behind aesthetically pleasing ruins that would last far longer without any maintenance at all. The idea was pioneered by German architect Albert Speer while planning for the 1936 Summer Olympics and published as "The Theory of Ruin Value" (Die Ruinenwerttheorie), although he was not its original inventor. The intention did not stretch only to the eventual collapse of the buildings, but rather assumed such buildings were inherently better designed and more imposing during their period of use.

The idea was supported by Adolf Hitler, who planned for such ruins to be a symbol of the greatness of the Third Reich, just as Ancient Greek and Roman ruins were symbolic of those civilisations.

🔗 Computing 🔗 Computer science 🔗 Computing/Software 🔗 Computing/Computer science

Comb sort is a relatively simple sorting algorithm originally designed by Włodzimierz Dobosiewicz and Artur Borowy in 1980, later rediscovered by Stephen Lacey and Richard Box in 1991. Comb sort improves on bubble sort.

The cryotron is a switch that operates using superconductivity. The cryotron works on the principle that magnetic fields destroy superconductivity. This simple device consists of two superconducting wires (e.g. tantalum and niobium) with different critical temperature (Tc). The cryotron was invented by Dudley Allen Buck of the Massachusetts Institute of Technology Lincoln Laboratory.

As described by Buck, a straight wire of tantalum (having lower Tc) is wrapped around with a wire of niobium in a single layer coil. Both wires are electrically isolated from each other. When this device is immersed in a liquid helium bath both wires become superconducting and hence offer no resistance to the passage of electric current. Tantalum in superconducting state can carry large amount of current as compared to its normal state. Now when current is passed through the niobium coil (wrapped around tantalum) it produces a magnetic field, which in turn reduces (kills) the superconductivity of the tantalum wire and hence reduces the amount of the current that can flow through the tantalum wire. Hence one can control the amount of the current that can flow in the straight wire with the help of small current in the coiled wire. We can think of the tantalum straight wire as a "gate" and the coiled niobium as a "control".

The article by Buck includes descriptions of several logic circuits implemented using cryotrons, including: one stage of a binary adder, carry network, binary accumulator stage, and two stages of a cryotron stepping register.

A planar cryotron using thin films of lead and tin was developed in 1957 by John Bremer at General Electric's General Engineering Lab in Schenectady, New York. This was one of the first integrated circuits, although using superconductors rather than semiconductors. In the next few years, a demonstration computer was made and arrays with 2000 devices operated. A short history of this work is in the November 2007 newsletter of the IEEE History Center.

Juri Matisoo developed a version of the cryotron incorporating a Josephson junction switched by the magnetic field from a control wire. He also explained the shortcomings of traditional cryotrons in which the superconductive material must transition between superconducting and normal states to switch the device, and thus switch relatively slowly. Matisoo's cryotron switched between a conducting state in which 'pair tunneling' of electrons through the gate took place and a 'resistive' state where only single electrons were able to tunnel. The circuit was (like the traditional cryotron) capable of some amplification (i.e gain greater than unity) had a switching rate of less than 800 picoseconds. Although the requirement for cryogenic cooling limited its practicality, it wasn't until the late 2010s that commercial transistors came close to matching this performance.

There have been periods of renewed interest in various types of cryotron, IBM experimented with using them for limited applications in supercomputers during the 1980s and (as of 2020) there has been some investigation of their potential applications both to I/O and logic in prototype quantum computers.