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🔗 Computing

A Machine Identification Code (MIC), also known as printer steganography, yellow dots, tracking dots or secret dots, is a digital watermark which certain color laser printers and copiers leave on every single printed page, allowing identification of the device with which a document was printed and giving clues to the originator. Developed by Xerox and Canon in the mid-1980s, its existence became public only in 2004. In 2018, scientists developed privacy software to anonymize prints in order to support whistleblowers publishing their work.

🔗 Human rights 🔗 Russia 🔗 Crime 🔗 Religion 🔗 Islam 🔗 LGBT studies 🔗 Sociology 🔗 Chechnya 🔗 Discrimination 🔗 Correction and Detention Facilities 🔗 Sexology and sexuality

Anti-gay purges in the Chechen Republic, a part of the Russian Federation, have included forced disappearances — secret abductions, imprisonment, torture — and extrajudicial killing by authorities targeting persons based on their perceived sexual orientation. An unknown number of people, who authorities detained on suspicion of being gay or bisexual, have reportedly died after being held in what human rights groups and eyewitnesses have called concentration camps.

Allegations were initially reported on 1 April 2017 in Novaya Gazeta, a Russian-language opposition newspaper, which reported that since February 2017 over 100 men had allegedly been detained and tortured and at least three had died in an extrajudicial killing. The paper, citing its sources in the Chechen special services, called the wave of detentions a "prophylactic sweep". The journalist who first reported on the subject went into hiding. There have been calls for reprisals against journalists who report on the situation.

As news spread of Chechen authorities' actions, which have been described as part of a systematic anti-LGBT purge, Russian and international activists scrambled to evacuate survivors of the camps and other vulnerable Chechens but were met with difficulty obtaining visas to conduct them safely beyond Russia.

The reports of the persecution were met with a variety of reactions worldwide. The Head of the Chechen Republic Ramzan Kadyrov denied not only the occurrence of any persecution but also the existence of gay men in Chechnya, adding that such people would be killed by their own families. Officials in Moscow were skeptical, although in late May the Russian government reportedly agreed to send an investigative team to Chechnya. Numerous national leaders and other public figures in the West condemned Chechnya's actions, and protests were held in Russia and elsewhere. A report released in December 2018 by the Organization for Security and Cooperation in Europe (OSCE) confirmed claims that persecution of LGBT persons had taken place and was ignored by authorities.

On 11 January 2019, it was reported that another 'gay purge' had begun in the country in December 2018, with several gay men and women being detained. The Russian LGBT Network believes that around 40 persons were detained and two killed.

🔗 England 🔗 English Royalty

The Groom of the Stool (formally styled: "Groom of the King's Close Stool") was the most intimate of an English monarch's courtiers, responsible for assisting the king in excretion and ablution.

The physical intimacy of the role naturally led to his becoming a man in whom much confidence was placed by his royal master and with whom many royal secrets were shared as a matter of course. This secret information—while it would never have been revealed, for it would have led to the discredit of his honour—in turn led to his becoming feared and respected and therefore powerful within the royal court in his own right. The office developed gradually over decades and centuries into one of administration of the royal finances, and under Henry VII, the Groom of the Stool became a powerful official involved in setting national fiscal policy, under the "chamber system".

Later, the office was renamed Groom of the Stole. The Tudor historian David Starkey classes this change as classic Victorianism: "When the Victorians came to look at this office, they spelt it s-t-o-l-e, and imagined all kinds of fictions about elaborate robes draped around the neck of the monarch at the coronation;" however, the change is in fact seen as early as the 17th century.

🔗 Visual arts

Artist's Shit (Italian: Merda d'artista) is a 1961 artwork by the Italian artist Piero Manzoni. The work consists of 90 tin cans, each reportedly filled with 30 grams (1.1 oz) of faeces, and measuring 4.8 by 6.5 centimetres (1.9 in × 2.6 in), with a label in Italian, English, French, and German stating:

Artist's Shit
Contents 30 gr net
Freshly preserved
Produced and tinned
in May 1961

🔗 Computing 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Computing/Software 🔗 Cryptography 🔗 Cryptography/Computer science

Pretty Good Privacy (PGP) is an encryption program that provides cryptographic privacy and authentication for data communication. PGP is used for signing, encrypting, and decrypting texts, e-mails, files, directories, and whole disk partitions and to increase the security of e-mail communications. Phil Zimmermann developed PGP in 1991.

PGP and similar software follow the OpenPGP, an open standard of PGP encryption software, standard (RFC 4880) for encrypting and decrypting data.

🔗 London 🔗 British Museum 🔗 Classical Greece and Rome 🔗 History of Science 🔗 Archaeology 🔗 Visual arts 🔗 Glass

The Lycurgus Cup is a 4th-century Roman glass cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it: red when lit from behind and green when lit from in front. It is the only complete Roman glass object made from this type of glass, and the one exhibiting the most impressive change in colour; it has been described as "the most spectacular glass of the period, fittingly decorated, which we know to have existed".

The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level. Many parts of the cage have been completely undercut. Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures, showing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the god Dionysus (Bacchus to the Romans). She was transformed into a vine that twined around the enraged king and restrained him, eventually killing him. Dionysus and two followers are shown taunting the king. The cup is the "only well-preserved figural example" of a cage cup.

The dichroic effect is achieved by making the glass with tiny proportions of nanoparticles of gold and silver dispersed in colloidal form throughout the glass material. The process used remains unclear, and it is likely that it was not well understood or controlled by the makers, and was probably discovered by accidental "contamination" with minutely ground gold and silver dust. The glass-makers may not even have known that gold was involved, as the quantities involved are so tiny; they may have come from a small proportion of gold in any silver added (most Roman silver contains small proportions of gold), or from traces of gold or gold leaf left by accident in the workshop, as residue on tools, or from other work. The very few other surviving fragments of Roman dichroic glass vary considerably in their two colours.

🔗 Mathematics

This is a list of mathematical symbols used in all branches of mathematics to express a formula or to represent a constant.

A mathematical concept is independent of the symbol chosen to represent it. For many of the symbols below, the symbol is usually synonymous with the corresponding concept (ultimately an arbitrary choice made as a result of the cumulative history of mathematics), but in some situations, a different convention may be used. For example, depending on context, the triple bar "≡" may represent congruence or a definition. However, in mathematical logic, numerical equality is sometimes represented by "≡" instead of "=", with the latter representing equality of well-formed formulas. In short, convention dictates the meaning.

Each symbol is shown both in HTML, whose display depends on the browser's access to an appropriate font installed on the particular device, and typeset as an image using TeX.

🔗 Robotics 🔗 Transhumanism

In aesthetics, the uncanny valley is a hypothesized relationship between the degree of an object's resemblance to a human being and the emotional response to such an object. The concept of the uncanny valley suggests that humanoid objects which imperfectly resemble actual human beings provoke uncanny or strangely familiar feelings of eeriness and revulsion in observers. "Valley" denotes a dip in the human observer's affinity for the replica, a relation that otherwise increases with the replica's human likeness.

Examples can be found in robotics, 3D computer animations, and lifelike dolls among others. With the increasing prevalence of virtual reality, augmented reality, and photorealistic computer animation, the "valley" has been cited in the popular press in reaction to the verisimilitude of the creation as it approaches indistinguishability from reality. The uncanny valley hypothesis predicts that an entity appearing almost human will risk eliciting cold, eerie feelings in viewers.

🔗 Computer science 🔗 Mathematics 🔗 Systems 🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Systems/Operations research

The knapsack problem is a problem in combinatorial optimization: Given a set of items, each with a weight and a value, determine the number of each item to include in a collection so that the total weight is less than or equal to a given limit and the total value is as large as possible. It derives its name from the problem faced by someone who is constrained by a fixed-size knapsack and must fill it with the most valuable items. The problem often arises in resource allocation where the decision makers have to choose from a set of non-divisible projects or tasks under a fixed budget or time constraint, respectively.

The knapsack problem has been studied for more than a century, with early works dating as far back as 1897. The name "knapsack problem" dates back to the early works of mathematician Tobias Dantzig (1884–1956), and refers to the commonplace problem of packing the most valuable or useful items without overloading the luggage.

🔗 Germany

A hunger stone (German: Hungerstein) is a type of hydrological landmark common in Central Europe. Hunger stones serve as famine memorials and warnings and were erected in Germany and in ethnic German settlements throughout Europe in the 15th through 19th centuries.

These stones were embedded into a river during droughts to mark the water level as a warning to future generations that they will have to endure famine-related hardships if the water sinks to this level again. One famous example in the Elbe river in Děčín, Czech Republic, has "Wenn du mich siehst, dann weine" (lit. "If you see me, weep") carved into it as a warning.

Many of these stones, featuring carvings or other artwork, were erected following the hunger crisis of 1816–1817 caused by the eruptions of the Tambora volcano.

In 1918, a hunger stone on the bed of the Elbe River, near Tetschen, became exposed during a period of low water coincident to the wartime famines of World War I. Similar hunger stones in the river were uncovered again during a drought in 2018.