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🔗 Human rights 🔗 Soviet Union 🔗 Russia 🔗 Military history 🔗 Crime 🔗 Death 🔗 Socialism 🔗 Poland 🔗 Military history/World War II 🔗 Military history/Russian, Soviet and CIS military history 🔗 Russia/history of Russia 🔗 Military history/Polish military history 🔗 Military history/European military history

The Katyn massacre (Polish: zbrodnia katyńska, "Katyń crime"; Russian: Катынская резня Katynskaya reznya, "Katyn massacre", or Russian: Катынский расстрел, "Katyn execution by shooting") was a series of mass executions of about 22,000 Polish military officers and intelligentsia carried out by the Soviet Union, specifically the NKVD ("People's Commissariat for Internal Affairs", the Soviet secret police) in April and May 1940. Though the killings also occurred in the Kalinin and Kharkiv prisons and elsewhere, the massacre is named after the Katyn Forest, where some of the mass graves were first discovered.

The massacre was initiated in NKVD chief Lavrentiy Beria's proposal of 5 March 1940 to execute all captive members of the Polish officer corps, approved by the Soviet Politburo led by Joseph Stalin. Of the total killed, about 8,000 were officers imprisoned during the 1939 Soviet invasion of Poland, another 6,000 were police officers, and the remaining 8,000 were Polish intelligentsia the Soviets deemed to be "intelligence agents, gendarmes, landowners, saboteurs, factory owners, lawyers, officials, and priests". The Polish Army officer class was representative of the multi-ethnic Polish state; the murdered included ethnic Poles, Polish Ukrainians, Belarusians, and Polish Jews including the Chief Rabbi of the Polish Army, Baruch Steinberg.

The government of Nazi Germany announced the discovery of mass graves in the Katyn Forest in April 1943. Stalin severed diplomatic relations with the London-based Polish government-in-exile when it asked for an investigation by the International Committee of the Red Cross. The USSR claimed the Nazis had killed the victims, and it continued to deny responsibility for the massacres until 1990, when it officially acknowledged and condemned the killings by the NKVD, as well as the subsequent cover-up by the Soviet government.

An investigation conducted by the office of the Prosecutors General of the Soviet Union (1990–1991) and the Russian Federation (1991–2004) confirmed Soviet responsibility for the massacres, but refused to classify this action as a war crime or as an act of mass murder. The investigation was closed on the grounds the perpetrators were dead, and since the Russian government would not classify the dead as victims of the Great Purge, formal posthumous rehabilitation was deemed inapplicable.

In November 2010, the Russian State Duma approved a declaration blaming Stalin and other Soviet officials for ordering the massacre.

🔗 Film 🔗 Film/American cinema

The Black Maria ( mə-RY-ə) was Thomas Edison's film production studio in West Orange, New Jersey. It was the world's first film studio.

🔗 Novels 🔗 Novels/Short story

"The Red One" is a short story by Jack London. It was first published in the October 1918 issue of The Cosmopolitan, two years after London's death. The story was reprinted in the same year by MacMillan, in a collection of London's stories of the same name.

🔗 Mathematics

In mathematics, Euler's identity (also known as Euler's equation) is the equality

${\displaystyle e^{i\pi }+1=0}$

where

e is Euler's number, the base of natural logarithms,

i is the imaginary unit, which by definition satisfies i² = −1, and

π is pi, the ratio of the circumference of a circle to its diameter.

Euler's identity is named after the Swiss mathematician Leonhard Euler. It is considered to be an exemplar of mathematical beauty as it shows a profound connection between the most fundamental numbers in mathematics.

🔗 Physiology 🔗 Molecular Biology 🔗 Physiology/cell 🔗 Molecular Biology/Molecular and Cell Biology

Peto's paradox is an observation that at the species level, the incidence of cancer does not appear to correlate with the number of cells in an organism. For example, the incidence of cancer in humans is much higher than the incidence of cancer in whales, despite whales having more cells than humans. If the probability of carcinogenesis were constant across cells, one would expect whales to have a higher incidence of cancer than humans. Peto's paradox is named after English statistician and epidemiologist Richard Peto, who first observed the connection.

🔗 Marine life 🔗 Animals

Iridogorgia chewbacca is a species of deep-sea bamboo coral in the family Chrysogorgiidae. Named after the Star Wars character Chewbacca due to its long, flexible, "hairy" branches that evoke the Wookiee's fur, the species was formally described in 2025. It inhabits rocky seafloors in the tropical western Pacific Ocean at depths exceeding 400 meters, where it forms solitary colonies up to 1.2 meters tall.

🔗 Climate change 🔗 Environment 🔗 Antarctica 🔗 Glaciers

The Western Antarctic Ice Sheet (WAIS) is the segment of the continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. The WAIS is classified as a marine-based ice sheet, meaning that its bed lies well below sea level and its edges flow into floating ice shelves. The WAIS is bounded by the Ross Ice Shelf, the Ronne Ice Shelf, and outlet glaciers that drain into the Amundsen Sea.

🔗 Computer science 🔗 Mathematics

Tupper's self-referential formula is a formula that visually represents itself when graphed at a specific location in the (x, y) plane.

🔗 Technology

A blast valve is used to protect a shelter, such as a fallout shelter or bunker, from the effects of sudden outside air pressure changes. A nuclear weapon creates a shock wave, which may produce sudden pressure changes of more than an atmosphere (about 1 bar) even several kilometres from the detonation point. After the shock wave passes, a sudden negative pressure follows.

If such pressure waves enter a shelter, they will likely do substantial harm to occupants and equipment. A blast valve is placed in air intake/exhaust pipes, that remains open normally, but automatically closes when strong pressure is applied in either direction. Blast dampers operate in the same fashion and are related or identical to blast valves, the former name however is generally used to describe blast mitigation devices, for more conventional explosive events.

A typical blast valve has entries of 15–30 cm diameter, and a larger centre section. Within the centre section is a disk mounted on an axle, with weak springs that keep it centred, away from both entries. Pressure displaces the disk along the axle, until it plugs one entry or the other. After the blast, the springs return the disk to the centre, re-opening the valve.

Another type of blast valve employs rounded metal tubes held in place by springs. As pressure rises it pushes the tubes against the frame of the valve closing the opening. These valves are typically unidirectional in airflow and are employed in large wall structures where large amounts of airflow is required.

One form of blast valve, popularized by the book Nuclear War Survival Skills and tested by ORNL is worn flat rubber tire treads nailed or bolted to frames strong enough to resist the maximum overpressure, with tested closing times cited as being identical to commercial grade blast valves, however the use of this form of blast valve design must also take the risk of the flammable rubber catching fire into consideration.

🔗 Philosophy 🔗 Skepticism 🔗 Philosophy/Logic 🔗 Psychology 🔗 Cognitive science

A cognitive bias is a systematic pattern of deviation from norm or rationality in judgment. Individuals create their own "subjective reality" from their perception of the input. An individual's construction of reality, not the objective input, may dictate their behavior in the world. Thus, cognitive biases may sometimes lead to perceptual distortion, inaccurate judgment, illogical interpretation, or what is broadly called irrationality.

Some cognitive biases are presumably adaptive. Cognitive biases may lead to more effective actions in a given context. Furthermore, allowing cognitive biases enables faster decisions which can be desirable when timeliness is more valuable than accuracy, as illustrated in heuristics. Other cognitive biases are a "by-product" of human processing limitations, resulting from a lack of appropriate mental mechanisms (bounded rationality), impact of individual's constitution and biological state (see embodied cognition), or simply from a limited capacity for information processing.

A continually evolving list of cognitive biases has been identified over the last six decades of research on human judgment and decision-making in cognitive science, social psychology, and behavioral economics. Daniel Kahneman and Tversky (1996) argue that cognitive biases have efficient practical implications for areas including clinical judgment, entrepreneurship, finance, and management.