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🔗 Mathematics

A prime number (or a prime) is a natural number greater than 1 that cannot be formed by multiplying two smaller natural numbers. A natural number greater than 1 that is not prime is called a composite number. For example, 5 is prime because the only ways of writing it as a product, 1 × 5 or 5 × 1, involve 5 itself. However, 6 is composite because it is the product of two numbers (2 × 3) that are both smaller than 6. Primes are central in number theory because of the fundamental theorem of arithmetic: every natural number greater than 1 is either a prime itself or can be factorized as a product of primes that is unique up to their order.

The property of being prime is called primality. A simple but slow method of checking the primality of a given number ${\displaystyle n}$, called trial division, tests whether ${\displaystyle n}$ is a multiple of any integer between 2 and ${\displaystyle {\sqrt {n}}}$. Faster algorithms include the Miller–Rabin primality test, which is fast but has a small chance of error, and the AKS primality test, which always produces the correct answer in polynomial time but is too slow to be practical. Particularly fast methods are available for numbers of special forms, such as Mersenne numbers. As of December 2018 the largest known prime number has 24,862,048 decimal digits.

There are infinitely many primes, as demonstrated by Euclid around 300 BC. No known simple formula separates prime numbers from composite numbers. However, the distribution of primes within the natural numbers in the large can be statistically modelled. The first result in that direction is the prime number theorem, proven at the end of the 19th century, which says that the probability of a randomly chosen number being prime is inversely proportional to its number of digits, that is, to its logarithm.

Several historical questions regarding prime numbers are still unsolved. These include Goldbach's conjecture, that every even integer greater than 2 can be expressed as the sum of two primes, and the twin prime conjecture, that there are infinitely many pairs of primes having just one even number between them. Such questions spurred the development of various branches of number theory, focusing on analytic or algebraic aspects of numbers. Primes are used in several routines in information technology, such as public-key cryptography, which relies on the difficulty of factoring large numbers into their prime factors. In abstract algebra, objects that behave in a generalized way like prime numbers include prime elements and prime ideals.

🔗 Computer science 🔗 Mathematics

In combinatory logic for computer science, a fixed-point combinator (or fixpoint combinator),^: p.26 is a higher-order function (i.e. a function which takes a function as argument) that returns some fixed point (a value that is mapped to itself) of its argument function, if one exists.

Formally, if ${\displaystyle {\textsf {fix}}}$ is a fixed-point combinator and the function ${\displaystyle f}$ has one or more fixed points, then ${\displaystyle {\textsf {fix}}\ f}$ is one of these fixed points, i.e.

${\displaystyle f\ ({\textsf {fix}}\ f)={\textsf {fix}}\ f\ .}$

Fixed-point combinators can be defined in the lambda calculus and in functional programming languages and provide a means to allow for recursive definitions.

🔗 Medicine 🔗 Viruses 🔗 Dogs 🔗 Cats 🔗 Neuroscience 🔗 Microbiology 🔗 Medicine/Neurology 🔗 Rodents 🔗 Medicine/Translation 🔗 Veterinary medicine 🔗 Medicine/Dermatology

Rabies is a viral disease that causes inflammation of the brain in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness. Once symptoms appear, the result is nearly always death. The time period between contracting the disease and the start of symptoms is usually one to three months, but can vary from less than one week to more than one year. The time depends on the distance the virus must travel along peripheral nerves to reach the central nervous system.

Rabies is caused by lyssaviruses, including the rabies virus and Australian bat lyssavirus. It is spread when an infected animal bites or scratches a human or other animal. Saliva from an infected animal can also transmit rabies if the saliva comes into contact with the eyes, mouth, or nose. Globally, dogs are the most common animal involved. In countries where dogs commonly have the disease, more than 99% of rabies cases are the direct result of dog bites. In the Americas, bat bites are the most common source of rabies infections in humans, and less than 5% of cases are from dogs. Rodents are very rarely infected with rabies. The disease can be diagnosed only after the start of symptoms.

Animal control and vaccination programs have decreased the risk of rabies from dogs in a number of regions of the world. Immunizing people before they are exposed is recommended for those at high risk, including those who work with bats or who spend prolonged periods in areas of the world where rabies is common. In people who have been exposed to rabies, the rabies vaccine and sometimes rabies immunoglobulin are effective in preventing the disease if the person receives the treatment before the start of rabies symptoms. Washing bites and scratches for 15 minutes with soap and water, povidone-iodine, or detergent may reduce the number of viral particles and may be somewhat effective at preventing transmission. As of 2016, only fourteen people had survived a rabies infection after showing symptoms.

Rabies caused about 17,400 human deaths worldwide in 2015. More than 95% of human deaths from rabies occur in Africa and Asia. About 40% of deaths occur in children under the age of 15. Rabies is present in more than 150 countries and on all continents but Antarctica. More than 3 billion people live in regions of the world where rabies occurs. A number of countries, including Australia and Japan, as well as much of Western Europe, do not have rabies among dogs. Many Pacific islands do not have rabies at all. It is classified as a neglected tropical disease.

🔗 Russia 🔗 China

"China's final warning" (Russian: Последнее китайское предупреждение) is a Russian proverb meaning a warning that carries no real consequences.

🔗 International relations 🔗 France 🔗 Military history 🔗 Terrorism 🔗 New Zealand 🔗 Military history/Intelligence 🔗 International relations/International law 🔗 Military history/Maritime warfare 🔗 Military history/French military history 🔗 Shipwrecks 🔗 International relations/United Nations 🔗 New Zealand/New Zealand politics 🔗 Military history/European military history 🔗 Crime and Criminal Biography 🔗 Crime and Criminal Biography/Terrorism 🔗 Auckland

The sinking of the Rainbow Warrior, codenamed Opération Satanique, was a bombing operation by the "action" branch of the French foreign intelligence services, the Direction générale de la sécurité extérieure (DGSE), carried out on 10 July 1985. During the operation, two operatives sank the flagship of the Greenpeace fleet, the Rainbow Warrior, at the Port of Auckland in New Zealand on its way to a protest against a planned French nuclear test in Moruroa. Fernando Pereira, a photographer, drowned on the sinking ship.

France initially denied responsibility, but two French agents were captured by New Zealand Police and charged with arson, conspiracy to commit arson, willful damage, and murder. As the truth came out, the scandal resulted in the resignation of the French Defence Minister Charles Hernu. The two agents pleaded guilty to manslaughter and were sentenced to ten years in prison. They spent a little over two years confined to the French island of Hao before being freed by the French government.

Several political figures, including then New Zealand Prime Minister David Lange, have referred to the bombing as an act of terrorism or state-sponsored terrorism.

🔗 Philosophy 🔗 Philosophy/Philosophy of mind

The hard problem of consciousness is the problem of explaining why and how sentient organisms have qualia or phenomenal experiences—how and why it is that some internal states are subjective, felt states, such as heat or pain, rather than merely nonsubjective, unfelt states, as in a thermostat or a toaster. The philosopher David Chalmers, who introduced the term "hard problem" of consciousness, contrasts this with the "easy problems" of explaining the ability to discriminate, integrate information, report mental states, focus attention, and so forth. Easy problems are (relatively) easy because all that is required for their solution is to specify a mechanism that can perform the function. That is, regardless of how complex or poorly understood the phenomena of the easy problems may be, they can eventually be understood by relying entirely on standard scientific methodologies. Chalmers claims that the problem of experience is distinct from this set and will "persist even when the performance of all the relevant functions is explained".

The existence of a "hard problem" is controversial. It has been accepted by philosophers of mind such as Joseph Levine, Colin McGinn, and Ned Block and cognitive neuroscientists such as Francisco Varela, Giulio Tononi, and Christof Koch. However, its existence is disputed by philosophers of mind such as Daniel Dennett, Massimo Pigliucci, and Keith Frankish and cognitive neuroscientists such as Stanislas Dehaene and Bernard Baars.

🔗 Biography 🔗 Syria

Bassel Khartabil (Arabic: باسل خرطبيل‎), also known as Bassel Safadi (Arabic: باسل صفدي‎), (22 May 1981, Damascus – 3 October 2015) was a Palestinian Syrian open-source software developer. On 15 March 2012, the one-year anniversary of the Syrian uprising, he was detained by the Syrian government at Adra Prison in Damascus. Between then and 3 October 2015, he had been transferred to an unknown location, probably to be judged by a military court. On 7 October 2015, Human Rights Watch and 30 other human rights organizations issued a letter demanding that Khartabil's whereabouts be disclosed. On 11 November 2015, rumors surfaced that Khartabil had been secretly sentenced to death. In August 2017, his wife made public that Khartabil had been executed by the Syrian regime shortly after his disappearance in 2015.

Khartabil was born in Damascus and raised in Syria, where he specialized in open source software development. He was chief technology officer (CTO) and co-founder of collaborative research company Aiki Lab and was CTO of Al-Aous, a publishing and research institution dedicated to archaeological sciences and arts in Syria. He has served as project lead and public affiliate for Creative Commons Syria, and has contributed to Mozilla Firefox, Wikipedia, Openclipart, Fabricatorz, and Sharism. He "is credited with opening up the Internet in Syria and vastly extending online access and knowledge to the Syrian people."

His last work included an open, 3D virtual reconstruction of the ancient city of Palmyra in Syria, real time visualization, and development with Fabricatorz for the web programming framework Aiki Framework. This was later created and displayed in his honor.

On February 7, 2018, the Bassel Khartabil Free Culture Fellowship was announced in Bassel's memory. The fellowship awards $50,000, including additional support, to outstanding individuals developing open culture in their communities. The fellowship was created by Creative Commons, Fabricatorz Foundation, Jimmy Wales Foundation, Mozilla, #NEWPALMYRA, and Wikimedia.

🔗 Germany 🔗 Architecture 🔗 Poland

Drzymała's wagon (Polish: wóz Drzymały) was a house on wheels built by Michał Drzymała as a protest against Imperial Germany's policy of Germanization in its Polish territories. Its owner, the peasant Michał Drzymała (1857-1937), was not only able to circumvent German building regulations by moving his home every day, but with his wagon-home became a Polish folk hero during the Partitions of Poland.

In 1886, by resolution of the Prussian Landtag, a Settlement Commission had been established to encourage German settlement in the Province of Posen and West Prussia. The Commission was empowered to purchase vacant property of the Polish szlachta and sell it to approved German applicants. The Prussian government regarded this as a measure designed to counteract the German "Flight from the East" (Ostflucht) and reduce the number of Poles, who were migrating to the area in hundreds of thousands looking for work. In Polish eyes, the establishment of the Commission was an aggressive measure designed to drive Poles from their lands.

While the campaign against Polish landownership largely missed its aims, it produced a strong opposition with its own hero, Drzymała. In 1904 he purchased a plot of land in Pogradowitz in the Posen district of Bomst, but found that the newly implemented Prussian Feuerstättengesetz ("furnace law") enabled local officials to deny him as a Pole the permission to build a permanent dwelling with an oven on his land. The law considered any place of stay a house if it stayed in one place for more than 24 hours. To get around the rule, he set himself up in a former circus caravan and for several years tenaciously defied in the courts all attempts to remove him. Each day, Drzymała moved the wagon a short distance, thereby exploiting the loophole and avoiding any legal penalties, until in 1909 he was able to buy an existent farmhouse nearby.

The case attracted publicity all over Germany. The German Kulturkampf measures and the Colonization Commission ultimately succeeded in stimulating the Polish national sentiment that they had been designed to suppress.

🔗 Germany 🔗 Germany/Hamburg 🔗 Germany/German transportation

Old Elbe Tunnel or St. Pauli Elbe Tunnel (German: Alter Elbtunnel colloquially or St. Pauli Elbtunnel officially) which opened in 1911, is a pedestrian and vehicle tunnel in Hamburg. The 426 m (1,398 ft) long tunnel was a technical sensation; 24 m (80 ft) beneath the surface, two 6 m (20 ft) diameter tubes connect central Hamburg with the docks and shipyards on the south side of the river Elbe. This was a big improvement for tens of thousands of workers in one of the busiest harbors in the world.

Six large lifts on either side of the tunnel carry pedestrians and vehicles to the bottom. The two tunnels are both still in operation, though due to their limited capacity by today's standards, other bridges and tunnels have been built and taken over most of the traffic.

In 2008 approximately 300,000 cars, 63,000 bicycles, and 700,000 pedestrians used the tunnel. The tunnel is opened 24 hours for pedestrians and bicycles. For motorized vehicles, opening times are currently Monday to Friday from 5:20 a.m. to 8:00 p.m. and on Saturdays from 5:20 a.m. to 4:00 p.m.