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🔗 Physics 🔗 Astronomy 🔗 Geology 🔗 Mythology 🔗 Iceland 🔗 Norse history and culture 🔗 Mythology/Norse mythology

The sunstone (Icelandic: sólarsteinn) is a type of mineral attested in several 13th–14th-century written sources in Iceland, one of which describes its use to locate the Sun in a completely overcast sky. Sunstones are also mentioned in the inventories of several churches and one monastery in 14th–15th-century Iceland and Germany.

A theory exists that the sunstone had polarizing attributes and was used as a navigational instrument by seafarers in the Viking Age. A stone found in 2002 off Alderney, in the wreck of a 16th-century warship, may lend evidence of the existence of sunstones as navigational devices.

🔗 Biography 🔗 Aviation 🔗 Spaceflight 🔗 Military history 🔗 Military history/Military aviation 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Biography/science and academia 🔗 Military history/Military biography 🔗 Biography/military biography 🔗 Aviation/aerospace biography 🔗 Military history/Cold War 🔗 Pritzker Military Library 🔗 Scouting 🔗 Ohio 🔗 Project-independent assessment 🔗 Spaceflight/adopt an astronaut 🔗 Cleveland

James Arthur Lovell Jr. ( LUV-əl; March 25, 1928 – August 7, 2025) was an American astronaut, naval aviator, test pilot and mechanical engineer. In 1968, as command module pilot of Apollo 8, he became, with Frank Borman and William Anders, one of the first three astronauts to fly to and orbit the Moon. He then commanded the Apollo 13 lunar mission in 1970 which, after a critical failure en route, looped around the Moon and returned safely to Earth. He acted in a few movies, such as The Man Who Fell to Earth (1976) and Apollo 13 (1995; uncredited).

A graduate of the United States Naval Academy in Annapolis, Maryland, in the class of 1952, Lovell flew F2H Banshee night fighters. This included a Western Pacific deployment aboard the aircraft carrier USS Shangri-La. In January 1958, he entered a six-month test pilot training course at the Naval Air Test Center at Naval Air Station Patuxent River, Maryland, with Class 20 and graduated at the top of the class. He was then assigned to Electronics Test, working with radar, and in 1960 he became the Navy's McDonnell Douglas F-4 Phantom II program manager. The following year he became a flight instructor and safety engineering officer at Naval Air Station Oceana in Virginia Beach, Virginia, and completed Aviation Safety School at the University of Southern California.

Lovell was not selected by NASA as one of the Mercury Seven astronauts due to a temporarily high bilirubin count. He was accepted in September 1962 as one of the second group of astronauts needed for the Gemini and Apollo programs. Prior to Apollo, Lovell flew in space on two Gemini missions, Gemini 7 (with Borman) in 1965 and Gemini 12 in 1966. He was the first person to fly into space four times. One of 24 people to have flown to the Moon, Lovell was the first to fly to the moon twice, and the only human to have done so without landing. He was a recipient of the Congressional Space Medal of Honor and the Presidential Medal of Freedom. He co-authored the 1994 book Lost Moon, on which the 1995 film Apollo 13 was based. Lovell was featured in a cameo appearance in the film.

The thermal grill illusion is a sensory illusion originally demonstrated in 1896 by the Swedish physician Torsten Thunberg. The illusion is created by an interlaced grill of warm (e.g., 40°C/104°F) and cool (20°C/68°F) bars. When someone presses a hand against the grill, they experience the illusion of burning heat. But if the person presses against only a cool bar, only coolness is experienced; if the person presses against only a warm bar, only warmth is experienced.

Researchers have used the illusion to demonstrate that burning pain sensation is in fact a mixture of both cold and heat pain and that it is only the inhibition of the cold pain "channel" that reveals the heat component.

The illusion is demonstrated by positioning the middle finger in cold water and the ring and index fingers in warm water. Due to shortcomings in the body map - multisensory representation of the body - and this particular sensory input configuration, the brain is tricked into thinking the middle finger is in the warm water and the index and ring fingers in cold water.

In an fMRI experiment of the illusion, researchers recently observed an activation of the thalamus not seen for control stimuli. Also, activity in a portion of the right mid/anterior insula correlated with the perceived unpleasantness of the illusion.

🔗 Russia 🔗 Norway 🔗 Holidays 🔗 Sweden 🔗 Ethnic groups 🔗 Finland 🔗 Norse history and culture

The Sámi National Day is an ethnic national day for the Sámi (Saami) people that falls on February 6, the date when the first Sámi congress was held in 1917 in Trondheim, Norway. The congress was the first time that Norwegian and Swedish Sámi came together across national borders to work on finding solutions to common problems.

In 1992 at the 15th Sámi Conference in Helsinki, Finland, a resolution was passed that Sámi National Day should be celebrated on February 6 to commemorate the first Sámi congress in 1917, that Sami National Day is for all Sámi, regardless of where they live, and on that day the Sámi flag should be flown and the Sámi anthem sung in the local Sámi language. The first time Sami National Day was celebrated was in 1993, when the International Year of Indigenous People was proclaimed open in Jokkmokk, Sweden by the United Nations.

Since then, celebrating the day has become increasingly popular. In Norway, it is compulsory for municipal administrative buildings to fly the Norwegian flag, and optionally also the Sami flag, on February 6. Particularly notable is the celebration in Norway's capital Oslo, where the bells in the highest tower of Oslo City Hall play the Sami national anthem as the flags are raised. Some larger places have taken to arranging festivities in the week around the Sami National Day. The National Day has been included in the almanacs published by the University of Helsinki since 2004. The Norwegian, Swedish, and Finnish authorities recommend general flagging on the day.

By coincidence, February 6 was also the date representatives of the Sámi of the Kola Peninsula gathered annually to meet with Russian bureaucrats to debate and decide on issues of relevance to them. This assembly, called the Kola Sobbar, has been dubbed the "first Sámi Parliament" by the researcher Johan Albert Kalstad. However, the founding of the Kola Sobbar did not influence the choice of the date for Sámi People's Day, as the assembly existed only during the late 1800s and was largely forgotten until the early 2000s.

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Medicine 🔗 Chemicals 🔗 Occupational Safety and Health 🔗 Military history/World War I 🔗 Medicine/Toxicology

Chloropicrin, also known as PS and nitrochloroform, is a chemical compound currently used as a broad-spectrum antimicrobial, fungicide, herbicide, insecticide, and nematicide. It was used as a poison gas in World War I. Its chemical structural formula is Cl₃CNO₂.

🔗 United States 🔗 Biography 🔗 Computing 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Chicago 🔗 Catholicism 🔗 United States/Iowa

Mary Kenneth Keller, B.V.M. (December 17, 1913 – January 10, 1985) was an American Roman Catholic religious sister, educator and pioneer in computer science. She and Irving C. Tang were the first two people to earn a doctorate in computer science in the United States.

🔗 Crime 🔗 COVID-19 🔗 Women's History

The Signal for Help (or the Violence at Home Signal for Help) is a single-handed gesture that can be used by an individual to alert others that they feel threatened and need help over a video call, or in-person. It was originally created as a tool to combat the rise in domestic violence cases around the world as a result of the self-isolation measures related to the COVID-19 pandemic.

The signal is performed by holding one hand up with the thumb tucked into the palm, then folding the four other fingers down, symbolically trapping the thumb in the rest of the fingers. It was intentionally designed as a single continuous hand movement, rather than a sign held in one position, that could be made easily visible.

The Signal for Help was first introduced in Canada by the Canadian Women's Foundation on April 14, 2020, and on April 28, 2020 in the United States by the Women's Funding Network (WFN). It received widespread praise from local, national, and international news organizations for helping provide a modern solution to the issue of a rise in domestic violence cases.

Addressing concerns that abusers may become aware of such a widespread online initiative, the Canadian Women's Foundation and other organizations clarified that this signal is not "something that's going to save the day," but rather a tool someone could use to get help.

Instructions for what to do if an individual sees the signal, and how to check-in safely, were also created.

🔗 Computing 🔗 Computing/Software

"You aren't gonna need it" (YAGNI) is a principle of extreme programming (XP) that states a programmer should not add functionality until deemed necessary. XP co-founder Ron Jeffries has written: "Always implement things when you actually need them, never when you just foresee that you need them." Other forms of the phrase include "You aren't going to need it" and "You ain't gonna need it".

🔗 Computing 🔗 Computer science

The Rete algorithm ( REE-tee, RAY-tee, rarely REET, reh-TAY) is a pattern matching algorithm for implementing rule-based systems. The algorithm was developed to efficiently apply many rules or patterns to many objects, or facts, in a knowledge base. It is used to determine which of the system's rules should fire based on its data store, its facts. The Rete algorithm was designed by Charles L. Forgy of Carnegie Mellon University, first published in a working paper in 1974, and later elaborated in his 1979 Ph.D. thesis and a 1982 paper.

🔗 Chemicals 🔗 Plants

Cucurbitacin is a class of biochemical compounds that some plants – notably members of the pumpkin and gourd family, Cucurbitaceae – produce and which function as a defence against herbivores. Cucurbitacins are chemically classified as triterpenes, formally derived from cucurbitane, a triterpene hydrocarbon – specifically, from the unsaturated variant cucurbit-5-ene, or 19(10→9β)-abeo-10α-lanost-5-ene. They often occur as glycosides. They and their derivatives have been found in many plant families (including Brassicaceae, Cucurbitaceae, Scrophulariaceae, Begoniaceae, Elaeocarpaceae, Datiscaceae, Desfontainiaceae, Polemoniaceae, Primulaceae, Rubiaceae, Sterculiaceae, Rosaceae, and Thymelaeaceae), in some mushrooms (including Russula and Hebeloma) and even in some marine mollusks.

Cucurbitacins may be a taste deterrent in plants foraged by some animals and in some edible plants preferred by humans, like cucumbers and zucchinis. In laboratory research, cucurbitacins have cytotoxic properties and are under study for their potential biological activities.