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An emirp (prime spelled backwards) is a prime number that results in a different prime when its decimal digits are reversed. This definition excludes the related palindromic primes. The term reversible prime is used to mean the same as emirp, but may also, ambiguously, include the palindromic primes.

The sequence of emirps begins 13, 17, 31, 37, 71, 73, 79, 97, 107, 113, 149, 157, 167, 179, 199, 311, 337, 347, 359, 389, 701, 709, 733, 739, 743, 751, 761, 769, 907, 937, 941, 953, 967, 971, 983, 991, ... (sequence A006567 in the OEIS).

All non-palindromic permutable primes are emirps.

As of November 2009, the largest known emirp is 10¹⁰⁰⁰⁶+941992101×10⁴⁹⁹⁹+1, found by Jens Kruse Andersen in October 2007.

The term 'emirpimes' (singular) is used also in places to treat semiprimes in a similar way. That is, an emirpimes is a semiprime that is also a (distinct) semiprime upon reversing its digits.

🔗 Disaster management 🔗 Medicine 🔗 China 🔗 Food and drink 🔗 Medicine/Toxicology 🔗 Taiwan

Gutter oil (Chinese: 地沟油; pinyin: dìgōu yóu, or 餿水油; sōushuǐ yóu) is oil which has been recycled from waste oil collected from sources such as restaurant fryers, grease traps, slaughterhouse waste and fatbergs.

Reprocessing of used cooking oil is often very rudimentary; techniques include filtration, boiling, refining, and the removal of some adulterants. It is then packaged and resold as a cheaper alternative to normal cooking oil. Another version of gutter oil uses discarded animal parts, animal fat and skins, internal organs, and expired or otherwise low-quality meat, which is then cooked in large vats in order to extract the oil. Used kitchen oil can be purchased for between $859 and $937 per ton, while the cleaned and refined product can sell for $1,560 per ton. Thus there is great economic incentive to produce and sell gutter oil.

It was estimated in 2011 that up to one in every ten lower-market restaurant meals consumed in China is prepared with recycled oil. As Feng Ping of the China Meat Research Center has said: "The illegal oil shows no difference in appearance and indicators after refining and purification because the law breakers are skillful at coping with the established standards."

Some street vendors and restaurants in China and Taiwan have illegally used recycled oil unfit for human consumption for the purposes of cooking food, leading to a crackdown against such establishments by the Chinese and Taiwanese governments.

Gutter oil is an acceptable raw ingredient for products that are not for human consumption, such as soap, rubber, bio-fuel, and cosmetics.

🔗 United States 🔗 Spaceflight 🔗 Philately 🔗 Guild of Copy Editors

The Apollo 15 postal covers incident, a 1972 NASA scandal, involved the astronauts of Apollo 15, who carried about 400 unauthorized postal covers into space and to the Moon's surface on the Lunar Module Falcon. Some of the envelopes were sold at high prices by West German stamp dealer Hermann Sieger, and are known as "Sieger covers". The crew of Apollo 15, David Scott, Alfred Worden and James Irwin, agreed to take payments for carrying the covers; though they returned the money, they were reprimanded by NASA. Amid much press coverage of the incident, the astronauts were called before a closed session of a Senate committee and never flew in space again.

The three astronauts and an acquaintance, Horst Eiermann, had agreed to have the covers made and taken into space. Each astronaut was to receive about $7,000. Scott arranged to have the covers postmarked on the morning of the Apollo 15 launch on July 26, 1971. They were packaged for space and brought to him as he prepared for liftoff. Due to an error, they were not included on the list of the personal items he was taking into space. The covers spent July 30 to August 2 on the Moon inside Falcon. On August 7, the date of splashdown, the covers were postmarked again on the recovery carrier USS Okinawa. One hundred were sent to Eiermann (and passed on to Sieger); the remaining covers were divided among the astronauts.

Worden had agreed to carry 144 additional covers, largely for an acquaintance, F. Herrick Herrick; these had been approved for travel to space. Apollo 15 carried a total of approximately 641 covers. In late 1971, when NASA learned that the Herrick covers were being sold, the astronauts' supervisor, Deke Slayton, warned Worden to avoid further commercialization of what he had been allowed to take into space. After Slayton heard of the Sieger arrangement, he removed the three as backup crew members for Apollo 17, though the astronauts had by then refused compensation from Sieger and Eiermann. The Sieger matter became generally known in the newspapers in June 1972. There was widespread coverage; some said astronauts should not be allowed to reap personal profits from NASA missions.

By 1977, all three former astronauts had left NASA. In 1983, Worden sued, and the covers were returned to them. One of the postal covers given to Sieger sold for over $50,000 in 2014.

🔗 Japan

The Metropolitan Area Outer Underground Discharge Channel (Japanese: 首都圏外郭放水路, Hepburn: shutoken gaikaku hōsuiro), 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 6.4 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 10 MW (13,000 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.

🔗 China 🔗 Politics

Document Number Nine (or Document No. 9), more properly the Communiqué on the Current State of the Ideological Sphere (also translated as the Briefing on the Current Situation in the Ideological Realm), is a confidential internal document widely circulated within the Communist Party of China in 2013 by the General Office of the Communist Party of China. The document was first circulated in July 2012. The document warns of seven dangerous Western values, allegedly including media freedom and judicial independence. Teaching on any of the seven topics is forbidden. There is an emphasis on controlling and preventing communication using the internet of ideas subversive to one party rule. The document was issued in the context of planned economic reforms and increased calls for political reform. It has been described as a critique of the "liberal ways of thinking".

The document was not made available to public by the Communist Party or any branches of the Chinese government, but in July 2013 was allegedly leaked by Chinese dissident journalist Gao Yu, who was in turn sentenced to a seven-year imprisonment for "leaking state secrets".

It is unclear whether this document is official Chinese policy or just a faction within the party. However, The New York Times suggests that it "bears the unmistakable imprimatur of Xi Jinping". It is thought that Document No. 9 was issued by the Central Committee General Office, and would have required the approval of Mr. Xi and other top leaders. A severe crackdown against human rights lawyers, media outlets, academics, and other such independent thinkers has followed the document's publication.

🔗 Physics

A nanoscale vacuum-channel transistor (NVCT) is a theoretically visioned transistor in which the electron transport medium is a vacuum. In a traditional solid-state transistor, a semiconductor channel exists between the source and the drain, and the current flows through the semiconductor. However, in a nanoscale vacuum-channel transistor, no material exists between the source and the drain, and therefore, the current flows through the vacuum. However, experimental realization of such a transistor has not been demonstrated.

Theoretically, a vacuum-channel transistor is expected to operate faster than a traditional solid-state transistor, and have higher power output. Moreover, vacuum-channel transistors are expected to operate at higher temperature and radiation level than a traditional transistor making them suitable for space application.

The development of vacuum-channel transistors is still at a very early research stage, and there are only limited study in recent literature such as vertical field-emitter vacuum-channel transistor, gate-insulated planar electrodes vacuum-channel transistor, vertical vacuum-channel transistor, and all-around gate vacuum-channel transistor.

🔗 Brands 🔗 Chemistry 🔗 Invention 🔗 Polymers

Starlite is an intumescent material claimed to be able to withstand and insulate from extreme heat. It was invented by British amateur chemist and hairdresser Maurice Ward (1933-2011) during the 1970s and 1980s, and received significant publicity after coverage of the material aired in 1990 on the BBC science and technology show Tomorrow's World. The name Starlite was coined by Ward's granddaughter Kimberly.

The American company Thermashield, LLC claims to have acquired the rights to Starlite in 2013 and replicated it. It is the only company to have itself publicly demonstrated the technology and have samples tested by third parties.

🔗 Iran 🔗 Alternative Views 🔗 Iraq

The Baghdad Battery or Parthian Battery is a set of three artifacts which were found together: a ceramic pot, a tube of copper, and a rod of iron. It was discovered in modern Khujut Rabu, Iraq, close to the metropolis of Ctesiphon, the capital of the Parthian (150 BC – 223 AD) and Sasanian (224–650 AD) empires of Persia, and it is considered to date from either of these periods.

Its origin and purpose remain unclear. It was hypothesized by some researchers that the object functioned as a galvanic cell, possibly used for electroplating, or some kind of electrotherapy, but there is no electroplated object known from this period. An alternative explanation is that it functioned as a storage vessel for sacred scrolls.

🔗 Lists 🔗 Philosophy 🔗 Skepticism 🔗 Philosophy/Logic

In reasoning to argue a claim, a fallacy is reasoning that is evaluated as logically incorrect and that undermines the logical validity of the argument and permits its recognition as unsound. Regardless of their soundness, all registers and manners of speech can demonstrate fallacies.

Because of their variety of structure and application, fallacies are challenging to classify so as to satisfy all practitioners. Fallacies can be classified strictly by either their structure or content, such as classifying them as formal fallacies or informal fallacies, respectively. The classification of informal fallacies may be subdivided into categories such as linguistic, relevance through omission, relevance through intrusion, and relevance through presumption. On the other hand, fallacies may be classified by the process by which they occur, such as material fallacies (content), verbal fallacies (linguistic), and again formal fallacies (error in inference). In turn, material fallacies may be placed into the more general category of informal fallacies, while formal fallacies may be clearly placed into the more precise category of logical (deductive) fallacies. Yet, verbal fallacies may be placed into either informal or deductive classifications; compare equivocation which is a word or phrase based ambiguity (e.g., "he is mad", which may refer to either him being angry or clinically insane) to the fallacy of composition which is premise and inference based ambiguity (e.g., "this must be a good basketball team because each of its members is an outstanding player").

The conscious or habitual use of fallacies as rhetorical devices is prevalent in the desire to persuade when the focus is more on communication and eliciting common agreement rather than on the correctness of the reasoning. The effective use of a fallacy by an orator may be considered clever, but by the same token, the reasoning of that orator should be recognized as unsound, and thus the orator's claim, supported by an unsound argument, will be regarded as unfounded and dismissed.

🔗 Aviation 🔗 Aviation/airline

Janet, sometimes called Janet Airlines, is the unofficial name given to a highly classified fleet of passenger aircraft operated for the United States Department of the Air Force as an employee shuttle to transport military and contractor employees. The purpose is to pick up the employees at their home airport, and take them to their place of work. Then, in the afternoon, they take the employees back to their home airports. The airline mainly serves the Nevada National Security Site (most notably Area 51 and the Tonopah Test Range), from a private terminal at Las Vegas's McCarran International Airport.

The airline's aircraft are generally unmarked, but do have a red paint strip along the windows of the aircraft, which gives some sort of hint at Janet being the operator.