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๐ XOR Linked List
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- "XOR Linked List" | 2012-05-03 | 153 Upvotes 84 Comments
- "Things you shouldn't do: Two pointers in one field." | 2010-05-16 | 42 Upvotes 20 Comments
- "XOR Linked List: A Curious List Structure" | 2007-12-03 | 10 Upvotes 3 Comments
๐ BogleโChandler Case
The BogleโChandler case refers to the mysterious deaths of Gilbert Bogle and Margaret Chandler on the banks of the Lane Cove River in Sydney, Australia on 1 January 1963. The case became famous because of the circumstances in which the bodies were found and because the cause of death could not be established. In 2006 a filmmaker discovered evidence to suggest the cause of death was hydrogen sulphide gas. In the early hours of 1 January an eruption of gas from the polluted river bed may have occurred, causing the noxious fumes to pool in deadly quantities in the grove.
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- "BogleโChandler Case" | 2019-12-22 | 23 Upvotes 1 Comments
๐ COMEFROM
In computer programming, COMEFROM (or COME FROM) is an obscure control flow structure used in some programming languages, originally as a joke. COMEFROM
is roughly the opposite of GOTO
in that it can take the execution state from any arbitrary point in code to a COMEFROM
statement.
The point in code where the state transfer happens is usually given as a parameter to COMEFROM
. Whether the transfer happens before or after the instruction at the specified transfer point depends on the language used. Depending on the language used, multiple COMEFROM
s referencing the same departure point may be invalid, be non-deterministic, be executed in some sort of defined priority, or even induce parallel or otherwise concurrent execution as seen in Threaded Intercal.
A simple example of a "COMEFROM x
" statement is a label x
(which does not need to be physically located anywhere near its corresponding COMEFROM
) that acts as a "trap door". When code execution reaches the label, control gets passed to the statement following the COMEFROM
. This may also be conditional, passing control only if a condition is satisfied, analogous to a GOTO within an IF statement. The primary difference from GOTO is that GOTO only depends on the local structure of the code, while COMEFROM depends on the global structure โ a GOTO transfers control when it reaches a line with a GOTO statement, while COMEFROM requires scanning the entire program or scope to see if any COMEFROM statements are in scope for the line, and then verifying if a condition is hit. The effect of this is primarily to make debugging (and understanding the control flow of the program) extremely difficult, since there is no indication near the line or label in question that control will mysteriously jump to another point of the program โ one must study the entire program to see if any COMEFROM statements reference that line or label.
Debugger hooks can be used to implement a COMEFROM statement, as in the humorous Python goto module; see below. This also can be implemented with the gcc feature "asm goto" as used by the Linux kernel configuration option CONFIG_JUMP_LABEL. A no-op has its location stored, to be replaced by a jump to an executable fragment that at its end returns to the instruction after the no-op.
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- "COMEFROM" | 2019-10-19 | 82 Upvotes 24 Comments
- "COMEFROM" | 2011-11-17 | 41 Upvotes 20 Comments
๐ Tokyo's Underground Discharge Channel
The Metropolitan Area Outer Underground Discharge Channel (Japanese: ้ฆ้ฝๅๅค้ญๆพๆฐด่ทฏ, Hepburn: shutoken gaikaku hลsuiro), is an underground water infrastructure project in Kasukabe, Saitama, Japan. It is the world's largest underground flood water diversion facility, built to mitigate overflowing of the city's major waterways and rivers during rain and typhoon seasons. It is located between Showa in Tokyo and Kasukabe in Saitama prefecture, on the outskirts of the city of Tokyo in the Greater Tokyo Area, Japan.
Work on the project started in 1992 and was completed by early 2006. It consists of five concrete containment silos with heights of 65 m and diameters of 32 m, connected by 6.4ย km of tunnels, 50 m beneath the surface, as well as a large water tank with a height of 25.4 m, with a length of 177m, with a width of 78m, and with 59 massive pillars connected to 78 10ย MW (13,000ย hp) pumps that can pump up to 200 tons of water into the Edo River per second.
"Ryukyukan" for Underground Exploration Museum of The Metropolitan Area Outer Underground Discharge Channel is also a tourist attraction and can be visited for 3.000 Yen; however, as the tours are conducted in Japanese, a Japanese speaker must be present in the group to act as a translator for non-Japanese speakers.
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- "Tokyo's Underground Discharge Channel" | 2019-04-30 | 96 Upvotes 40 Comments
๐ Usury
Usury () is the practice of making unethical or immoral monetary loans that unfairly enrich the lender. The term may be used in a moral senseโcondemning taking advantage of others' misfortunesโor in a legal sense, where an interest rate is charged in excess of the maximum rate that is allowed by law. A loan may be considered usurious because of excessive or abusive interest rates or other factors defined by the laws of a state. Someone who practices usury can be called a usurer, but in modern colloquial English may be called a loan shark.
In many historical societies including ancient Christian, Jewish, and Islamic societies, usury meant the charging of interest of any kind, and was considered wrong, or was made illegal. During the Sutra period in India (7th to 2nd centuries BC) there were laws prohibiting the highest castes from practicing usury. Similar condemnations are found in religious texts from Buddhism, Judaism (ribbit in Hebrew), Christianity, and Islam (riba in Arabic). At times, many states from ancient Greece to ancient Rome have outlawed loans with any interest. Though the Roman Empire eventually allowed loans with carefully restricted interest rates, the Catholic Church in medieval Europe, as well as the Reformed Churches, regarded the charging of interest at any rate as sinful (as well as charging a fee for the use of money, such as at a bureau de change). Religious prohibitions on usury are predicated upon the belief that charging interest on a loan is a sin.
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- "Usury" | 2023-03-13 | 25 Upvotes 9 Comments
๐ Mechanical television
Mechanical television or mechanical scan television is a television system that relies on a mechanical scanning device, such as a rotating disk with holes in it or a rotating mirror, to scan the scene and generate the video signal, and a similar mechanical device at the receiver to display the picture. This contrasts with modern television technology, which uses electronic scanning methods, for example electron beams in cathode ray tube (CRT) televisions, and liquid-crystal displays (LCD), to create and display the picture.
Mechanical-scanning methods were used in the earliest experimental television systems in the 1920s and 1930s. One of the first experimental wireless television transmissions was by John Logie Baird on November 25, 1925, in London. By 1928 many radio stations were broadcasting experimental television programs using mechanical systems. However the technology never produced images of sufficient quality to become popular with the public. Mechanical-scan systems were largely superseded by electronic-scan technology in the mid-1930s, which was used in the first commercially successful television broadcasts which began in the late 1930s in Great Britain.
A mechanical television receiver is also called a televisor in some countries.
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- "Mechanical television" | 2015-12-10 | 10 Upvotes 1 Comments
๐ Sousveillance
Sousveillance ( soo-VAY-lษnss) is the recording of an activity by a participant in the activity, typically by way of small wearable or portable personal technologies. The term "sousveillance", coined by Steve Mann, stems from the contrasting French words sur, meaning "above", and sous, meaning "below", i.e. "surveillance" denotes the "eye-in-the-sky" watching from above, whereas "sousveillance" denotes bringing the camera or other means of observation down to human level, either physically (mounting cameras on people rather than on buildings), or hierarchically (ordinary people doing the watching, rather than higher authorities or architectures doing the watching).
While surveillance and sousveillance both generally refer to visual monitoring, the terms also denote other forms of monitoring such as audio surveillance or sousveillance. In the audio sense (e.g. recording of phone conversations), sousveillance is referred to as "one party consent".
Undersight (inverse oversight) is sousveillance at high-level, e.g. "citizen undersight" being reciprocal to a congressional oversight committee or the like.
Inverse surveillance is a subset of sousveillance with a particular emphasis on the "watchful vigilance from underneath" and a form of surveillance inquiry or legal protection involving the recording, monitoring, study, or analysis of surveillance systems, proponents of surveillance, and possibly also recordings of authority figures and their actions. Inverse surveillance is typically an activity undertaken by those who are generally the subject of surveillance, and may thus be thought of as a form of an ethnography or ethnomethodology study (i.e. an analysis of the surveilled from the perspective of a participant in a society under surveillance).
Sousveillance typically involves community-based recording from first person perspectives, without necessarily involving any specific political agenda, whereas inverse-surveillance is a form of sousveillance that is typically directed at, or used to collect data to analyze or study, surveillance or its proponents (e.g., the actions of police or protestors at a protest rally).
Sousveillance is not necessarily countersurveillance; i.e. sousveillance can be used to "counter" the forces of surveillance, or it can also be used together with surveillance to create a more complete "veillance" ("Surveillance is a half-truth without sousveillance"). The question of "Who watches the watchers" is dealt with more properly under the topic of metaveillance (the veillance of veillance) than sousveillance.
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- "Sousveillance" | 2018-11-20 | 154 Upvotes 70 Comments
๐ Engines of Creation, by K. Eric Drexler (1986)
Engines of Creation: The Coming Era of Nanotechnology is a 1986 molecular nanotechnology book written by K. Eric Drexler with a foreword by Marvin Minsky. An updated version was released in 2007. The book has been translated into Japanese, French, Spanish, Italian, Russian, and Chinese.
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- "Engines of Creation, by K. Eric Drexler (1986)" | 2019-07-28 | 19 Upvotes 10 Comments
๐ Iran Air Flight 655 (Wikipedia)
Iran Air Flight 655 was a scheduled passenger flight from Tehran to Dubai via Bandar Abbas that was shot down on 3ย July 1988 by an SM-2MR surface-to-air missile fired from USSย Vincennes, a guided-missile cruiser of the United States Navy. The aircraft, an Airbus A300, was destroyed and all 290 people on board were killed. The jet was hit while flying over Iran's territorial waters in the Persian Gulf, along the flight's usual route, shortly after departing Bandar Abbas International Airport, the flight's stopover location. The incident occurred during the final stages of the IranโIraq War, which had been continuing for nearly eight years. Vincennes had entered Iranian territory after one of its helicopters drew warning fire from Iranian speedboats operating within Iranian territorial limits.
The reason for the shootdown has been disputed between the governments of the two countries. According to the U.S., the Vincennes crew had incorrectly identified the Airbus as an attacking F-14 Tomcat, a U.S.-made jet fighter that had been part of the Iranian Air Force inventory since the 1970s. While the F-14s had been supplied to Iran in an air-to-air configuration, the Vincennes crew had been briefed that the Iranian F-14s were equipped with air-to-ground ordnance. Vincennes had made ten attempts to contact the aircraft both on military and on civilian frequencies, but had received no response. According to Iran, the cruiser negligently shot down the aircraft, which was transmitting IFF squawks in Mode III, a signal that identified it as a civilian aircraft, and not Mode II as used by Iranian military aircraft. The event generated a great deal of criticism of the United States. Some analysts blamed the captain of Vincennes, William C. Rogers III, for overly aggressive behavior in a tense and dangerous environment. In the days immediately following the incident, President Ronald Reagan issued a written diplomatic note to the Iranian government, expressing deep regret. However, the U.S. continued to insist that Vincennes was acting in self-defense in international waters.
In 1996, the governments of the U.S. and Iran reached a settlement at the International Court of Justice which included the statement "...ย the United States recognized the aerial incident of 3ย July 1988 as a terrible human tragedy and expressed deep regret over the loss of lives caused by the incidentย ..." When President Ronald Reagan was directly asked if he considered the statement an apology, Reagan replied, "Yes." As part of the settlement, even though the U.S. government did not admit legal liability or formally apologize to Iran, it still agreed to pay US$61.8 million on an ex gratia basis in compensation to the families of the Iranian victims. The shootdown was the deadliest aviation disaster involving an Airbus A300.
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- "Iran Air Flight 655 (Wikipedia)" | 2020-01-08 | 57 Upvotes 24 Comments
๐ IBM Common User Access
Common User Access (CUA) is a standard for user interfaces to operating systems and computer programs. It was developed by IBM and first published in 1987 as part of their Systems Application Architecture. Used originally in the MVS/ESA, VM/CMS, OS/400, OS/2 and Microsoft Windows operating systems, parts of the CUA standard are now implemented in programs for other operating systems, including variants of Unix. It is also used by Java AWT and Swing.
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- "IBM Common User Access" | 2021-05-20 | 32 Upvotes 21 Comments