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🔗 Internet 🔗 Computing 🔗 Law 🔗 Computing/Software 🔗 Computing/Websites 🔗 Computing/Networking

In computer networking, HTTP 451 Unavailable For Legal Reasons is an error status code of the HTTP protocol to be displayed when the user requests a resource which cannot be served for legal reasons, such as a web page censored by a government. The number 451 is a reference to Ray Bradbury's 1953 dystopian novel Fahrenheit 451, in which books are outlawed. 451 intends to provide more information than 403 Forbidden, which is often used for the same purpose. This status code is standardized in RFC 7725.

Examples of situations where an HTTP 451 error code could be displayed include web pages deemed a danger to national security, or web pages deemed to violate copyright, privacy, blasphemy laws, or any other law or court order.

The RFC is specific that a 451 response does not indicate whether the resource exists but requests for it have been blocked, if the resource has been removed for legal reasons and no longer exists, or even if the resource has never existed, but any discussion of its topic has been legally forbidden (see superinjunction). Some sites have previously returned HTTP 404 (Not Found) or similar if they are not legally permitted to disclose that the resource has been removed. Such a tactic is used in the United Kingdom by some internet service providers utilising the Internet Watch Foundation blacklist, returning a 404 message or another error message instead of showing a message indicating the site is blocked.

The status code was formally proposed in 2013 by Tim Bray, following earlier informal proposals by Chris Applegate in 2008 and Terence Eden in 2012. It was approved by the IESG on December 18, 2015. It was published as RFC 7725 in February 2016.

HTTP 451 was mentioned by the BBC's From Our Own Correspondent program, as an indication of the effects of sanctions on Sudan and the inability to access Airbnb, iOS's App Store, or other Western web services.

After introduction of the GDPR in European Economic Area (EEA) many websites located outside EEA started to serve HTTP 451 instead of trying to comply with this new privacy law.

🔗 Computing

In computing, a pizza box is a style of case design for desktop computers or network switches. Pizza box cases tend to be wide and flat, normally 1.5 to 4 inches or 4 to 10 centimetres in height, resembling pizza delivery boxes and thus the name. This is in contrast to a tower system, whose case height is much greater than the width and has an "upright" appearance. In modern usage, the term "pizza box" is normally reserved for very flat cases with height no more than 2 inches (51 mm), while those taller than 2 inches are referred to as desktop cases instead.

The common setup of a pizza box system is to have the display monitor placed directly on top of the case, which serves as a podium to elevate the monitor more towards the user's eye level, and to have other peripherals placed in front and alongside the case. Occasionally, the pizza box may be laid on its sides in a tower-like orientation.

Data General's Aviion Unix server was the first to coin the expression when it advertised in 1991 with the tagline "Who just fit mainframe power in a pizza box?", but most computers generally referred to as pizza box systems were high-end desktop systems such as Sun Microsystems workstations sold in the 1990s, most notably the SPARCstation 1 and SPARCstation 5. Other notable examples have been among the highest-performing desktop computers of their generations, including the SGI Indy, the NeXTstation, and the Amiga 1000, but the form factor was also seen in budget and lower-end lines such as the Macintosh LC family.

The original SPARCstation 1 design included an expansion bus technology, SBus, expressly designed for the form factor; expansion cards were small, especially in comparison to other expansion cards in use at the time such as VMEbus, and were mounted horizontally instead of vertically. PC-compatible computers in this type of case typically use the PCI expansion bus and are usually either a) limited to one or two horizontally placed expansion cards or b) require special low-profile expansion cards, shorter than the PCI cards regular PCs use.

The density of computing power and stackability of pizza box systems also made them attractive for use in data centers. Systems originally designed for desktop use were placed on shelves inside of 19-inch racks, sometimes requiring that part of their cases be cut off for them to fit. Since the late 1990s, pizza boxes have been a common form factor in office cubicles, data centers or industrial applications, where desktop space, rack room and density are critical. Servers in this form factor, as well as higher-end Ethernet switches, are now designed for rack mounting. Rack mount 1U computers come in all types of configurations and depths.

The pizza box form factor for smaller personal systems and thin clients remains in use well into the 21st century, though it is increasingly being superseded by laptops, nettops or All-in-One PC designs that embed the already size-reduced computer onto the keyboard or display monitor.

🔗 Computer graphics

The Ramer–Douglas–Peucker algorithm, also known as the Douglas–Peucker algorithm and iterative end-point fit algorithm, is an algorithm that decimates a curve composed of line segments to a similar curve with fewer points.

🔗 Philately

Letterlocking is the act of folding and securing a written message which could be on papyrus, parchment, or paper, so that it does not require an envelope or additional enclosure. It is a document security tradition which utilizes folding and cutting. The process dates to the 13th century in Western history, corresponding with the availability of flexible writing paper. Letterlocking uses small slits, tab, and holes placed directly into a letter, which combined with folding techniques are used to secure the letter ("letterpacket"), preventing reading the letter without breaking seals or slips, providing a means of tamper resistance. These folds and holes may be additionally secured with string and sealing wax. A Scottish diplomat in Italy, William Keith of Delny, sent letters to James VI of Scotland which would tear in two if not opened with care.

Intricate letterlocking works contain artistic elements, demonstrating more than a utilitarian purpose. While the use of sealing techniques may have been limited to ecclesiastic and the nobility, letterlocking was historically performed by all classes of writers. An individual could also be recognised by their personal technique of folding, as was the case with Jane Whorwood, of whose letter Charles I, imprisoned in Carisbrooke Castle on the Isle of Wight, wrote: "This Note [...] I know, by the fowldings [...] that it is written by [Mrs Whorwood]".

Letterlocking is also a discipline focusing on "the materially engineered security and privacy of letters, both as a technology and a historically evolving tradition."

🔗 New Zealand 🔗 Antarctica

The McMurdo Dry Valleys are a row of largely snow-free valleys in Antarctica, located within Victoria Land west of McMurdo Sound. The Dry Valleys experience extremely low humidity and surrounding mountains prevent the flow of ice from nearby glaciers. The rocks here are granites and gneisses, and glacial tills dot this bedrock landscape, with loose gravel covering the ground. It is one of the driest places on Earth and has not seen rain for nearly 2 million years.

The region is one of the world's most extreme deserts, and includes many features including Lake Vida, a saline lake, and the Onyx River, a meltwater stream and Antarctica's longest river. Although no living organisms have been found in the permafrost here, endolithic photosynthetic bacteria have been found living in the relatively moist interior of rocks, and anaerobic bacteria, with a metabolism based on iron and sulfur, live under the Taylor Glacier.

🔗 Politics 🔗 Politics/American politics 🔗 Ohio

The Ohio nuclear bribery scandal is a 2020 political scandal in Ohio involving allegations that FirstEnergy paid roughly $60 million to Generation Now, a 501(c)(4) organization purportedly controlled by Speaker of the Ohio House of Representatives Larry Householder, in exchange for passing a $1.3 billion bailout for the struggling nuclear power operator. It was described as "likely the largest bribery, money laundering scheme ever perpetrated against the people of the state of Ohio" by U.S. Attorney David M. DeVillers, who charged Householder and four others with racketeering on July 21. According to prosecutors, FirstEnergy poured millions into the campaigns of 21 candidates during the 2018 Ohio House of Representatives election, which ultimately helped Householder replace Ryan Smith as Republican House speaker.

According to DeVillers in late July 2020, the investigation is far from over. "There are a lot of federal agents knocking on a lot of doors."

🔗 United States 🔗 Media 🔗 Popular Culture 🔗 Georgia (U.S. state) 🔗 United States/United States Presidents 🔗 Animals in media

The Jimmy Carter rabbit incident, sensationalized as the "killer rabbit attack" by the press, involved a swamp rabbit (Sylvilagus aquaticus) that swam toward then-U.S. President Jimmy Carter's fishing boat on April 20, 1979. The incident caught the imagination of the media after Carter's press secretary, Jody Powell, mentioned the event to a correspondent months later.

Political opponents argued that the incident was symbolic of Carter's purported weakness. According to Powell, anti-Carter political commentators went so far as to blame it for the Soviet invasion of Afghanistan and the Iran hostage crisis.

🔗 Computing 🔗 Computing/Software 🔗 Numismatics 🔗 Software 🔗 Software/Computing 🔗 Numismatics/Cryptocurrency 🔗 Cryptocurrency 🔗 Computing/Computer Security

Namecoin (Symbol: ℕ or NMC) is a cryptocurrency originally forked from bitcoin software. It is based on the code of bitcoin and uses the same proof-of-work algorithm. Like bitcoin, it is limited to 21 million coins.

Namecoin can store data within its own blockchain transaction database. The original proposal for Namecoin called for Namecoin to insert data into bitcoin's blockchain directly. Anticipating scaling difficulties with this approach, a shared proof-of-work (POW) system was proposed to secure new cryptocurrencies with different use cases.

Namecoin's flagship use case is the censorship-resistant top level domain .bit, which is functionally similar to .com or .net domains but is independent of ICANN, the main governing body for domain names.

🔗 Computer science 🔗 Mathematics

In numerical analysis, the Kahan summation algorithm, also known as compensated summation, significantly reduces the numerical error in the total obtained by adding a sequence of finite-precision floating-point numbers, compared to the obvious approach. This is done by keeping a separate running compensation (a variable to accumulate small errors).

In particular, simply summing n numbers in sequence has a worst-case error that grows proportional to n, and a root mean square error that grows as ${\displaystyle {\sqrt {n}}}$ for random inputs (the roundoff errors form a random walk). With compensated summation, the worst-case error bound is effectively independent of n, so a large number of values can be summed with an error that only depends on the floating-point precision.

The algorithm is attributed to William Kahan. Similar, earlier techniques are, for example, Bresenham's line algorithm, keeping track of the accumulated error in integer operations (although first documented around the same time) and the delta-sigma modulation (integrating, not just summing the error).

🔗 History 🔗 Mathematics 🔗 Books 🔗 Greece 🔗 History of Science

The Archimedes Palimpsest is a parchment codex palimpsest, originally a Byzantine Greek copy of a compilation of Archimedes and other authors. It contains two works of Archimedes that were thought to have been lost (the Ostomachion and the Method of Mechanical Theorems) and the only surviving original Greek edition of his work On Floating Bodies. The first version of the compilation is believed to have been produced by Isidorus of Miletus, the architect of the geometrically complex Hagia Sophia cathedral in Constantinople, sometime around AD 530. The copy found in the palimpsest was created from this original, also in Constantinople, during the Macedonian Renaissance (c. AD 950), a time when mathematics in the capital was being revived by the former Greek Orthodox bishop of Thessaloniki Leo the Geometer, a cousin of the Patriarch.

Following the sack of Constantinople by Western crusaders in 1204, the manuscript was taken to an isolated Greek monastery in Palestine, possibly to protect it from occupying crusaders, who often equated Greek script with heresy against their Latin church and either burned or looted many such texts (including at least two other copies of Archimedes). The complex manuscript was not appreciated at this remote monastery and was soon overwritten (1229) with a religious text. In 1899, nine hundred years after it was written, the manuscript was still in the possession of the Greek church, and back in Istanbul, where it was catalogued by the Greek scholar Papadopoulos-Kerameus, attracting the attention of Johan Heiberg. Heiberg visited the church library and was allowed to make detailed photographs in 1906. Most of the original text was still visible, and Heiberg published it in 1915. In 1922 the manuscript went missing in the midst of the evacuation of the Greek Orthodox library in Istanbul, during a tumultuous period following the World War I. Concealed for over 70 years by a Western businessman, forged pictures were painted on top of some text to increase resale value. Unable to sell the book privately, in 1998 the businessman's daughter risked a public auction in New York contested by the Greek church; the U.S. court ruled for the auction, and the manuscript was purchased by an anonymous buyer (rumored to be Jeff Bezos). The texts under the forged pictures, and previously unreadable texts, were revealed by analyzing images produced by ultraviolet, infrared, visible and raking light, and X-ray.

All images and transcriptions are now freely available on the web at the Archimedes Digital Palimpsest under the Creative Commons License CC BY.