Have a deep view into what people are curious about.

🔗 Norway

Norwegian Constitution Day is the national day of Norway and is an official public holiday observed on May 17 each year. Among Norwegians, the day is referred to simply as syttende mai (lit. "seventeenth May"), Nasjonaldagen (The National Day) or Grunnlovsdagen (The Constitution Day), although the latter is less frequent.

🔗 Computer science 🔗 Molecular and Cell Biology 🔗 Computational Biology

The Needleman–Wunsch algorithm is an algorithm used in bioinformatics to align protein or nucleotide sequences. It was one of the first applications of dynamic programming to compare biological sequences. The algorithm was developed by Saul B. Needleman and Christian D. Wunsch and published in 1970. The algorithm essentially divides a large problem (e.g. the full sequence) into a series of smaller problems, and it uses the solutions to the smaller problems to find an optimal solution to the larger problem. It is also sometimes referred to as the optimal matching algorithm and the global alignment technique. The Needleman–Wunsch algorithm is still widely used for optimal global alignment, particularly when the quality of the global alignment is of the utmost importance. The algorithm assigns a score to every possible alignment, and the purpose of the algorithm is to find all possible alignments having the highest score.

🔗 Physics 🔗 Physics/Acoustics

In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies.

With tuning instruments that can produce sustained tones, beats can be readily recognized. Tuning two tones to a unison will present a peculiar effect: when the two tones are close in pitch but not identical, the difference in frequency generates the beating. The volume varies like in a tremolo as the sounds alternately interfere constructively and destructively. As the two tones gradually approach unison, the beating slows down and may become so slow as to be imperceptible. As the two tones get further apart, their beat frequency starts to approach the range of human pitch perception, the beating starts to sound like a note, and a combination tone is produced. This combination tone can also be referred to as a missing fundamental, as the beat frequency of any two tones is equivalent to the frequency of their implied fundamental frequency.

🔗 Philosophy 🔗 Philosophy/Logic

The raven paradox, also known as Hempel's paradox, Hempel's ravens, or rarely the paradox of indoor ornithology, is a paradox arising from the question of what constitutes evidence for a statement. Observing objects that are neither black nor ravens may formally increase the likelihood that all ravens are black even though, intuitively, these observations are unrelated.

This problem was proposed by the logician Carl Gustav Hempel in the 1940s to illustrate a contradiction between inductive logic and intuition.

🔗 Board and table games

1000 Blank White Cards is a party card game played with cards in which the deck is created as part of the game. Though it has been played by adults in organized groups worldwide, 1000 Blank White Cards is also described as well-suited for children in Hoyle's Rules of Games. Since any game rules are contained on the cards (rather than existing as all-encompassing rules or in a rule book), 1000 Blank White Cards can be considered a sort of nomic. It can be played by any number of players and provides the opportunity for card creation and gameplay outside the scope of a single sitting. Creating new cards during the game, dealing with previous cards' effects, is allowed, and rule modification is encouraged as an integral part of gameplay.

🔗 Biography 🔗 Biography/science and academia 🔗 University of Pennsylvania

George Harry Heilmeier (May 22, 1936 – April 21, 2014) was an American engineer, manager, and a pioneering contributor to liquid crystal displays (LCDs), for which he was inducted into the National Inventors Hall of Fame. Heilmeier's work is an IEEE Milestone.

🔗 Aviation 🔗 Aviation/aircraft

A propfan, also called an open rotor engine, or unducted fan, is a type of aircraft engine related in concept to both the turboprop and turbofan, but distinct from both. The design is intended to offer the speed and performance of a turbofan, with the fuel economy of a turboprop. A propfan is typically designed with a large number of short, highly twisted blades, similar to a turbofan's bypass compressor (the fan itself). For this reason, the propfan has been variously described as an "unducted fan" or an "ultra-high-bypass (UHB) turbofan."

🔗 Architecture 🔗 Pakistan

Osama bin Laden's compound, known locally as the Waziristan Haveli (Urdu: وزیرستان حویلی‎), was an upper-class mansion that was used as a safe house for militant Islamist Osama bin Laden, who was shot and killed there by U.S. forces on May 2, 2011. The compound was located at the end of a dirt road 1,300 metres (0.8 mi) southwest of the Pakistan Military Academy in Bilal Town, Abbottabad, Pakistan, a suburb housing many retired military officers. Bin Laden was reported to have evaded capture by living in a section of the house for at least five years, having no Internet or phone connection, and hiding away from the public, who were allegedly unaware of his presence.

Completed in 2005, the main buildings in the compound lay on a 3,500-square-metre (38,000 sq ft) plot of land, much larger than those of nearby houses. Its perimeter was 3.7- to 5.5-metre (12 to 18 ft) concrete walls topped with barbed wire, and there were two security gates. The compound had very few windows. Little more than five years old, the compound's ramshackle buildings were badly in need of repainting. The grounds contained a well-kept vegetable garden, rabbits, some 100 chickens and a cow. The house itself did not stand out architecturally from others in the neighbourhood, except for its size and exaggerated security measures; for example, the third-floor balcony had a 2-metre (7 ft) privacy wall. Photographs inside the house showed excessive clutter and modest furnishings. After the American mission, there was extensive interest in and reporting about the compound and its design. To date, the Pakistani government has not responded to any allegations as to who had built the structure.

After the September 11 attacks in 2001, the U.S. searched for bin Laden for nearly 10 years. By tracking his courier Abu Ahmed al-Kuwaiti to the compound, U.S. officials surmised that bin Laden was hiding there. During a raid on May 2, 2011, 24 members of the United States Naval Special Warfare Development Group arrived by helicopter, breached a wall using explosives, and entered the compound in search of bin Laden. After the operation was completed and bin Laden was killed, Pakistan demolished the structure in February 2012.

🔗 Psychology

The Johari window is a technique designed to help people better understand their relationship with themselves and others. It was created by psychologists Joseph Luft (1916–2014) and Harrington Ingham (1916–1995) in 1955, and is used primarily in self-help groups and corporate settings as a heuristic exercise. Luft and Ingham named their model "Johari" using a combination of their first names.

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

Homomorphic encryption is a form of encryption that allows computation on ciphertexts, generating an encrypted result which, when decrypted, matches the result of the operations as if they had been performed on the plaintext.

Homomorphic encryption can be used for privacy-preserving outsourced storage and computation. This allows data to be encrypted and out-sourced to commercial cloud environments for processing, all while encrypted. In highly regulated industries, such as health care, homomorphic encryption can be used to enable new services by removing privacy barriers inhibiting data sharing. For example, predictive analytics in health care can be hard to apply due to medical data privacy concerns, but if the predictive analytics service provider can operate on encrypted data instead, these privacy concerns are diminished.