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π Foucault pendulum
The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist LΓ©on Foucault and conceived as an experiment to demonstrate the Earth's rotation. The pendulum was introduced in 1851 and was the first experiment to give simple, direct evidence of the earth's rotation. Foucault pendulums today are popular displays in science museums and universities.
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- "Foucault pendulum" | 2020-04-27 | 69 Upvotes 33 Comments
π Abu Ghraib prison human rights abuses
During the early stages of the Iraq War, members of the United States Army and the CIA committed a series of human rights violations and war crimes against detainees in the Abu Ghraib prison in Iraq, including physical and sexual abuse, torture, rape and the killing of Manadel al-Jamadi. The abuses came to public attention with the publication of photographs of the abuse by CBS News in April 2004. The incidents caused shock and outrage, receiving widespread condemnation within the United States and internationally.
The George W. Bush administration claimed that the abuses at Abu Ghraib were isolated incidents and not indicative of U.S. policy.:β328β This was disputed by humanitarian organizations including the Red Cross, Amnesty International, and Human Rights Watch; these organizations stated that the abuses at Abu Ghraib were part of a wider pattern of torture and brutal treatment at American overseas detention centers, including those in Iraq, in Afghanistan, and at Guantanamo Bay.:β328β
Documents popularly known as the Torture Memos came to light a few years later. These documents, prepared in the months leading up to the 2003 invasion of Iraq by the United States Department of Justice, authorized certain enhanced interrogation techniques (generally held to involve torture) of foreign detainees. The memoranda also argued that international humanitarian laws, such as the Geneva Conventions, did not apply to American interrogators overseas. Several subsequent U.S. Supreme Court decisions, including Hamdan v. Rumsfeld (2006), have overturned Bush administration policy, ruling that the Geneva Conventions do apply.
In response to the events at Abu Ghraib, the United States Department of Defense removed 17 soldiers and officers from duty. Eleven soldiers were charged with dereliction of duty, maltreatment, aggravated assault and battery. Between May 2004 and April 2006, these soldiers were court-martialed, convicted, sentenced to military prison, and dishonorably discharged from service. Two soldiers, found to have perpetrated many of the worst offenses at the prison, Specialist Charles Graner and PFC Lynndie England, were subject to more severe charges and received harsher sentences. Graner was convicted of assault, battery, conspiracy, maltreatment of detainees, committing indecent acts and dereliction of duty; he was sentenced to 10 years imprisonment and loss of rank, pay and benefits. England was convicted of conspiracy, maltreating detainees and committing an indecent act and sentenced to three years in prison. Brigadier General Janis Karpinski, the commanding officer of all detention facilities in Iraq, was reprimanded and demoted to the rank of colonel. Several more military personnel who were accused of perpetrating or authorizing the measures, including many of higher rank, were not prosecuted. In 2004, President George W. Bush and Defense Secretary Donald Rumsfeld apologized for the Abu Ghraib abuses.
π BerkShares
BerkShares is a local currency that circulates in The Berkshires region of Massachusetts. It was launched on September 29, 2006 by BerkShares Inc., with research and development assistance from the Schumacher Center for a New Economics. The BerkShares website lists around 400 businesses in Berkshire County that accept the currency. Since launch, over 10 million BerkShares have been issued from participating branch offices of local banks (as of February 2020, 9 branches of 3 different banks). The bills were designed by John Isaacs and were printed by Excelsior Printing on special paper with incorporated security features from Crane & Co.. BerkShares are pegged with an exchange rate to the US dollar, but the Schumacher Center has discussed the possibility of pegging its value to a basket of local goods in order to insulate the local economy against volatility in the US economy.
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- "BerkShares" | 2017-09-08 | 214 Upvotes 88 Comments
π Vocal Fry Register
The vocal fry register (also known as pulse register, laryngealization, pulse phonation, creaky voice, creak, croak, popcorning, glottal fry, glottal rattle, glottal scrape) is the lowest vocal register and is produced through a loose glottal closure that permits air to bubble through slowly with a popping or rattling sound of a very low frequency. During this phonation, the arytenoid cartilages in the larynx are drawn together, which causes the vocal folds to compress rather tightly and become relatively slack and compact. This process forms a large and irregularly vibrating mass within the vocal folds that produces the characteristic low popping or rattling sound when air passes through the glottal closure. The register (if well controlled) can extend far below the modal voice register, in some cases up to 8 octaves lower, such as in the case of Tim Storms who holds the world record for lowest frequency note ever produced by a human, a Gβ7, which is only 0.189Β Hz, inaudible to the human ear.
Vocal fry is thought to have become more common among young female speakers of American English in the early 21st century, with the style of speaking being considered informal, nonaggressive and urban-oriented.
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- "Vocal Fry Register" | 2023-10-07 | 42 Upvotes 45 Comments
π Slaughterbots
Slaughterbots is a 2017 arms-control advocacy video presenting a dramatized near-future scenario where swarms of inexpensive microdrones use artificial intelligence and facial recognition to assassinate political opponents based on preprogrammed criteria. The video was released onto YouTube by the Future of Life Institute and Stuart Russell, a professor of computer science at Berkeley, on 12 November 2017. The video quickly went viral, gaining over two million views. The video was also screened to the November 2017 United Nations Convention on Certain Conventional Weapons meeting in Geneva.
π How trains avoid colliding with each other
Signalling block systems enable the safe and efficient operation of railways by preventing collisions between trains. The basic principle is that a route is broken up into a series of sections or "blocks". Only one train may occupy a block at a time, and the blocks are sized to allow a train to stop within them. That ensures that a train always has time to stop before getting dangerously close to another train on the same line. The block system is referred to in the UK as the method of working, in the US as the method of operation, and in Australia as safeworking.
In most situations, a system of signals is used to control the passage of trains between the blocks. When a train enters a block, signals at both ends change to indicate that the block is occupied, typically using red lamps or indicator flags. When a train first enters a block, the rear of the same train has not yet left the previous block, so both blocks are marked as occupied. That ensures there is slightly less than one block length on either end of the train that is marked as occupied, so any other train approaching that section will have enough room to stop in time, even if the first train has stopped dead on the tracks. The previously-occupied block will only be marked unoccupied when the end of the train has entirely left it, leaving the entire block clear.
Block systems have the disadvantage that they limit the number of trains on a particular route to something fewer than the number of blocks. Since the route has a fixed length, increasing the number of trains requires the creation of more blocks, which means the blocks are shorter and trains have to operate at lower speeds in order to stop safely. As a result, the number and size of blocks are closely related to the overall route capacity, and cannot be changed easily because expensive alterations to the signals along the line would be required.
Block systems are used to control trains between stations and yards, but not normally within the yards, where some other method is used. Any block system is defined by its associated physical equipment and by the application of a relevant set of rules. Some systems involve the use of signals while others do not. Some systems are specifically designed for single track railways, on which there is a danger of both head-on and rear-end collision, as opposed to double track, on which the main danger is rear-end collisions.
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- "How trains avoid colliding with each other" | 2021-11-10 | 17 Upvotes 2 Comments
π Buridan's Ass
Buridan's ass is an illustration of a paradox in philosophy in the conception of free will. It refers to a hypothetical situation wherein an ass that is equally hungry and thirsty is placed precisely midway between a stack of hay and a pail of water. Since the paradox assumes the ass will always go to whichever is closer, it dies of both hunger and thirst since it cannot make any rational decision between the hay and water. A common variant of the paradox substitutes two identical piles of hay for the hay and water; the ass, unable to choose between the two, dies of hunger.
The paradox is named after the 14th-century French philosopher Jean Buridan, whose philosophy of moral determinism it satirizes. Although the illustration is named after Buridan, philosophers have discussed the concept before him, notably Aristotle, who used the example of a man equally hungry and thirsty, and Al-Ghazali, who used a man faced with the choice of equally good dates.
A version of this situation appears as metastability in digital electronics, when a circuit must decide between two states based on an input that is in itself undefined (neither zero nor one). Metastability becomes a problem if the circuit spends more time than it should in this "undecided" state, which is usually set by the speed of the clock the system is using.
π Open Cola
OpenCola is a brand of open-source cola, where the instructions for making it are freely available and modifiable. Anybody can make the drink, and anyone can modify and improve on the recipe. It was launched in 2001 by free software P2P company Opencola, to promote their open-source software concept.
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- "OpenCola (Drink)" | 2021-06-19 | 74 Upvotes 7 Comments
- "Open Cola" | 2016-09-21 | 146 Upvotes 66 Comments
- "Open Source Cola" | 2011-01-01 | 69 Upvotes 14 Comments
π Wang tile
Wang tiles (or Wang dominoes), first proposed by mathematician, logician, and philosopher Hao Wang in 1961, are a class of formal systems. They are modelled visually by square tiles with a color on each side. A set of such tiles is selected, and copies of the tiles are arranged side by side with matching colors, without rotating or reflecting them.
The basic question about a set of Wang tiles is whether it can tile the plane or not, i.e., whether an entire infinite plane can be filled this way. The next question is whether this can be done in a periodic pattern.
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- "Wang tile" | 2018-01-05 | 145 Upvotes 24 Comments
π Non-blocking synchronization
In computer science, an algorithm is called non-blocking if failure or suspension of any thread cannot cause failure or suspension of another thread; for some operations, these algorithms provide a useful alternative to traditional blocking implementations. A non-blocking algorithm is lock-free if there is guaranteed system-wide progress, and wait-free if there is also guaranteed per-thread progress.
The word "non-blocking" was traditionally used to describe telecommunications networks that could route a connection through a set of relays "without having to re-arrange existing calls", see Clos network. Also, if the telephone exchange "is not defective, it can always make the connection", see nonblocking minimal spanning switch.
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- "Non-blocking synchronization" | 2010-02-03 | 21 Upvotes 8 Comments