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π DeCSS Haiku
DeCSS haiku is a 465-stanza haiku poem written in 2001 by American hacker Seth Schoen as part of the protest action regarding the prosecution of Norwegian programmer Jon Lech Johansen for co-creating the DeCSS software. The poem, written in the spirit of civil disobedience against the DVD Copy Control Association, argues that "code is speech."
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- "DeCSS Haiku" | 2020-06-18 | 85 Upvotes 8 Comments
π Howland Will Forgery Trial
The Howland will forgery trial was a U.S. court case in 1868 to decide Henrietta Howland Robinson's contest of the will of Sylvia Ann Howland. It is famous for the forensic use of mathematics by Benjamin Peirce as an expert witness.
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- "Howland Will Forgery Trial" | 2020-07-31 | 66 Upvotes 21 Comments
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.
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- "Ocean Temperature" | 2023-05-13 | 87 Upvotes 53 Comments
π Synchronization gear
A synchronization gear, or a gun synchronizer, sometimes rather less accurately called an interrupter, is attached to the armament of a single-engine tractor-configuration aircraft so it can fire through the arc of its spinning propeller without bullets striking the blades. The idea presupposes a fixed armament directed by aiming the aircraft in which it is fitted at the target, rather than aiming the gun independently.
There are many practical problems, mostly arising from the inherently imprecise nature of an automatic gun's firing, the great (and varying) velocity of the blades of a spinning propeller, and the very high speed at which any gear synchronizing the two has to operate.
Design and experimentation with gun synchronization had been underway in France and Germany in 1913β1914, following the ideas of August Euler, who seems to have been the first to suggest mounting a fixed armament firing in the direction of flight (in 1910). However, the first practicalβif far from reliableβgear to enter operational service was that fitted to the Eindecker monoplane fighters, which entered squadron service with the German Air Service in mid-1915. The success of the Eindecker led to numerous gun synchronization devices, culminating in the reasonably reliable hydraulic British Constantinesco gear of 1917. By the end of the war German engineers were well on the way to perfecting a gear using an electrical rather than a mechanical or hydraulic link between the engine and the gun, with the gun being triggered by a solenoid rather than by a mechanical "trigger motor".
From 1918 to the mid-1930s the standard armament for a fighter aircraft remained two synchronized rifle-calibre machine guns, firing forward through the arc of the propeller. During the late 1930s, however, the main role of the fighter was increasingly seen as the destruction of large, all-metal bombers, for which the "traditional" light armament was inadequate.
Since it was impractical to try to fit more than one or two extra guns in the limited space available in the front of a single-engine aircraft's fuselage, this led to an increasing proportion of the armament being mounted in the wings, firing outside the arc of the propeller. There were in fact some advantages in dispensing with centrally mounted guns altogether. Nevertheless, the conclusive redundancy of synchronization gears did not finally come until the introduction of jet propulsion and the absence of a propeller for guns to be synchronized with.
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- "Synchronization gear" | 2020-01-19 | 54 Upvotes 15 Comments
π Countersteering
Countersteering is used by single-track vehicle operators, such as cyclists and motorcyclists, to initiate a turn toward a given direction by momentarily steering counter to the desired direction ("steer left to turn right"). To negotiate a turn successfully, the combined center of mass of the rider and the single-track vehicle must first be leaned in the direction of the turn, and steering briefly in the opposite direction causes that lean. The rider's action of countersteering is sometimes referred to as "giving a steering command".:β15β
The scientific literature does not provide a clear and comprehensive definition of countersteering. In fact, "a proper distinction between steer torque and steer angle ... is not always made."
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- "Countersteering" | 2022-09-14 | 105 Upvotes 137 Comments
π A hypercane is a hypothetical class of extreme tropical cyclone
A hypercane is a hypothetical class of extreme tropical cyclone that could form if ocean temperatures reached approximately 50Β Β°C (122Β Β°F), which is 15Β Β°C (27Β Β°F) warmer than the warmest ocean temperature ever recorded. Such an increase could be caused by a large asteroid or comet impact, a large supervolcanic eruption, a large submarine flood basalt, or extensive global warming. There is some speculation that a series of hypercanes resulting from an impact by a large asteroid or comet contributed to the demise of the non-avian dinosaurs. The hypothesis was created by Kerry Emanuel of MIT, who also coined the term.
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- "A hypercane is a hypothetical class of extreme tropical cyclone" | 2017-09-11 | 61 Upvotes 18 Comments
π Codex Seraphinianus
Codex Seraphinianus, originally published in 1981, is an illustrated encyclopedia of an imaginary world, created by Italian artist, architect and industrial designer Luigi Serafini between 1976 to 1978. It is approximately 360 pages (depending on edition) and written in an imaginary language.
Originally published in Italy, it has been released in several countries.
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- "Codex Seraphinianus" | 2023-09-17 | 17 Upvotes 1 Comments
- "Codex Seraphinianus" | 2020-09-10 | 10 Upvotes 1 Comments
π Imperial Airship Scheme
The British Imperial Airship Scheme was a 1920s project to improve communication between Britain and the distant countries of the British Empire by establishing air routes using airships. This led to the construction of two large and technically advanced airships, the R100 and the R101. The scheme was terminated in 1931 following the crash of R101 in October 1930 while attempting its first flight to India.
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- "Imperial Airship Scheme" | 2017-03-13 | 40 Upvotes 19 Comments
π Christmas Tree Exec
Christmas Tree EXEC was the first widely disruptive computer worm, which paralyzed several international computer networks in December 1987. The malware ran on the IBM VM/CMS operating system.
Written by a student at the Clausthal University of Technology in the REXX scripting language, it drew a crude Christmas tree as text graphics, then sent itself to each entry in the target's email contacts file. In this way it spread onto the European Academic Research Network (EARN), BITNET, and IBM's worldwide VNET. On all of these systems it caused massive disruption.
The core mechanism of the ILOVEYOU worm of 2000 was essentially the same as Christmas Tree, although it ran on PCs rather than mainframes, was spread over a different network, and was scripted using VBScript rather than REXX.
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- "Christmas Tree Exec" | 2025-12-06 | 22 Upvotes 2 Comments
π Fall of Saigon
The Fall of Saigon, also known as the Liberation of Saigon by North Vietnamese, was the capture of Saigon, the capital of South Vietnam, by the People's Army of Vietnam (PAVN) and the Viet Cong on 30 April 1975. The event marked the end of the Vietnam War and the start of a transition period to the formal reunification of Vietnam into the Socialist Republic of Vietnam.
The PAVN, under the command of General VΔn TiαΊΏn DΕ©ng, began their final attack on Saigon on 29 April 1975, with the Army of the Republic of Vietnam (ARVN) forces commanded by General Nguyα» n VΔn ToΓ n suffering a heavy artillery bombardment. By the afternoon of the next day, the PAVN had occupied the important points of the city and raised their flag over the South Vietnamese presidential palace. The city was renamed Hα» ChΓ Minh City, after the late North Vietnamese President Hα» ChΓ Minh.
The capture of the city was preceded by Operation Frequent Wind, the evacuation of almost all American civilian and military personnel in Saigon, along with tens of thousands of South Vietnamese civilians who had been associated with the Republic of Vietnam. A few Americans chose not to be evacuated. United States ground combat units had left South Vietnam more than two years prior to the fall of Saigon and were not available to assist with either the defense of Saigon or the evacuation. The evacuation was the largest helicopter evacuation in history. In addition to the flight of refugees, the end of the war and the institution of new rules by the communists contributed to a decline in the city's population.
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- "Fall of Saigon" | 2021-08-16 | 64 Upvotes 75 Comments