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🔗 Genetics 🔗 Amphibians and Reptiles

The fertile hybrids of European water frogs (genus Pelophylax) reproduce by hybridogenesis (hemiclonally). This means that during gametogenesis, they discard the genome of one of the parental species and produce gametes of the other parental species (containing a genome not recombined with the genome of the first parental species). The first parental genome is restored by fertilization of these gametes with gametes from the first species (sexual host). In all-hybrid populations of the edible frog Pelophylax kl. esculentus, however, triploid hybrids provide this missing genome.

Because half of the genome is transmitted to the next generation clonally (not excluded unrecombined intact genome), and only the other half sexually (recombined genome of the sexual host), the hybridogenesis is a hemiclonal mode of reproduction.

For example, the edible frog Pelophylax kl. esculentus (mostly RL genome), which is a hybridogenetic hybrid of the marsh frog P. ridibundus (RR) and the pool frog P. lessonae (LL), usually excludes the lessonae genome (L) and generates gametes of the P. ridibundus (R). In other words, edible frogs produce gametes of marsh frogs.

The hybrid populations are propagated, however, not by the above primary hybridisations, but predominantly by backcrosses with one of the parental species they coexist (live in sympatry) with (see below in the middle).

Since the hybridogenetic hybrids require another taxon as sexual host to reproduce, usually one of the parental species, they are called kleptons (with "kl." in scientific names).

There are three known hybridogenetic hybrids of the European water frogs:

• edible frog Pelophylax kl. esculentus (usually genotype RL):
  pool frog P. lessonae (LL) × P. ridibundus (RR)
• Graf's hybrid frog Pelophylax kl. grafi (PR):
  Perez's frog P. perezi (PP) × P. ridibundus (RR) or
  Perez's frog P. perezi (PP) × edible frog P. kl. esculentus (RE)
  (it is unclear which one crossing was the primary hybridisation)
• Italian edible frog Pelophylax kl. hispanicus (RB):
  Italian pool frog P. bergeri (BB) × P. ridibundus (RR)

🔗 Military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry 🔗 Cold War

Blue Peacock, renamed from Blue Bunny and originally Brown Bunny, was a British tactical nuclear weapon project in the 1950s.

The project's goal was to store a number of ten-kiloton nuclear mines in Germany, to be placed on the North German Plain and, in the event of Soviet invasion from the east, detonated by wire or an eight-day timer to:

... not only destroy facilities and installations over a large area, but ... deny occupation of the area to an enemy for an appreciable time due to contamination ...

🔗 Biography 🔗 Medicine 🔗 Biography/science and academia 🔗 Medicine/Society and Medicine

Min Chiu Li (Chinese: 李敏求; pinyin: Lǐ Mǐnqiú; 1919–1980) was a Chinese-American oncologist and cancer researcher. Li was the first scientist to use chemotherapy to cure widely metastatic, malignant cancer.

🔗 Education 🔗 Homeschooling 🔗 Alternative education

Unschooling is an informal learning that advocates learner-chosen activities as a primary means for learning. Unschooling students learn through their natural life experiences including play, household responsibilities, personal interests and curiosity, internships and work experience, travel, books, elective classes, family, mentors, and social interaction. Unschooling encourages exploration of activities initiated by the children themselves, believing that the more personal learning is, the more meaningful, well-understood and therefore useful it is to the child. While courses may occasionally be taken, unschooling questions the usefulness of standard curricula, conventional grading methods, and other features of traditional schooling in the education of each unique child.

The term "unschooling" was coined in the 1970s and used by educator John Holt, widely regarded as the father of unschooling. While unschooling is often considered a subset of homeschooling and homeschooling has been subject to widespread public debate, little media attention has been given to unschooling in particular.

Critics of unschooling see it as an extreme educational philosophy, with concerns that unschooled children will lack the social skills, structure, and motivation of their schooled peers, while proponents of unschooling say exactly the opposite is true: that self-directed education in a natural environment better equips a child to handle the "real world."

🔗 Law Enforcement 🔗 Chicago

A police riot is a riot carried out by the police; a riot that the police are responsible for instigating, escalating or sustaining as a violent confrontation; an event characterized by widespread police brutality; a mass police action that is violently undertaken against civilians for the purpose of political repression. The term "police riot" was popularized after its use in the Walker Report, which investigated the events surrounding the 1968 Democratic National Convention in Chicago to describe the "unrestrained and indiscriminate" violence that the police "inflicted upon persons who had broken no law, disobeyed no order, made no threat." In this sense a police riot refers to rioting carried out by the police (or those acting in a police capacity) rather than a riot carried out by people who may be motivated to a greater or lesser degree by grievances with the police (see the 1981 Toxteth riots or the 1992 Los Angeles Riots for examples of riots over policing rather than police riots).

🔗 Fashion

The Great Male Renunciation (French: Grande Renonciation masculine) is the historical phenomenon at the end of the 18th century in which Western men stopped using bright colours, elaborate shapes and variety in their dress, which were left to women's clothing. Instead men concentrated on minute differences of cut, and the quality of the plain cloth.

Coined by the Anglo-German psychologist John Flügel in 1930, it is considered a major turning point in the history of clothing in which the men relinquished their claim to adornment and beauty. Flugel asserted that men "abandoned their claim to be considered beautiful" and "henceforth aimed at being only useful". The Great Renunciation encouraged the establishment of the suit's monopoly on male dress codes at the beginning of the 19th century.

🔗 United States 🔗 Library of Congress 🔗 Geography 🔗 Maps 🔗 Libraries

The Waldseemüller map or Universalis Cosmographia ("Universal Cosmography") is a printed wall map of the world by German cartographer Martin Waldseemüller, originally published in April 1507. It is known as the first map to use the name "America". The name America is placed on what is now called South America on the main map. As explained in Cosmographiae Introductio, the name was bestowed in honor of the Italian Amerigo Vespucci.

The map is drafted on a modification of Ptolemy's second projection, expanded to accommodate the Americas and the high latitudes. A single copy of the map survives, presently housed at the Library of Congress in Washington, D.C.

Waldseemüller also created globe gores, printed maps designed to be cut out and pasted onto spheres to form globes of the Earth. The wall map, and his globe gores of the same date, depict the American continents in two pieces. These depictions differ from the small inset map in the top border of the wall map, which shows the two American continents joined by an isthmus.

🔗 Computing 🔗 Computing/Software 🔗 Computing/Free and open-source software 🔗 Plan 9

Plan 9 from Bell Labs is a distributed operating system, originating in the Computing Science Research Center (CSRC) at Bell Labs in the mid-1980s, and building on UNIX concepts first developed there in the late 1960s. The final official release was in early 2015.

Under Plan 9, UNIX's everything is a file metaphor is extended via a pervasive network-centric filesystem, and graphical user interface is assumed as a basis for almost all functionality, though it retains a heavily text-centric ideology.

The name Plan 9 from Bell Labs is a reference to the Ed Wood 1959 cult science fiction Z-movie Plan 9 from Outer Space. The name of the project's mascot is "Glenda, the Plan 9 Bunny". The system continues to be used and developed by operating system researchers and hobbyists.

🔗 Computer science

In computer science, a skip list is a data structure that allows ${\displaystyle {\mathcal {O}}(\log n)}$ search complexity as well as ${\displaystyle {\mathcal {O}}(\log n)}$ insertion complexity within an ordered sequence of ${\displaystyle n}$ elements. Thus it can get the best features of an array (for searching) while maintaining a linked list-like structure that allows insertion, which is not possible in an array. Fast search is made possible by maintaining a linked hierarchy of subsequences, with each successive subsequence skipping over fewer elements than the previous one (see the picture below on the right). Searching starts in the sparsest subsequence until two consecutive elements have been found, one smaller and one larger than or equal to the element searched for. Via the linked hierarchy, these two elements link to elements of the next sparsest subsequence, where searching is continued until finally we are searching in the full sequence. The elements that are skipped over may be chosen probabilistically or deterministically, with the former being more common.

🔗 Medicine

The Therac-25 was a computer-controlled radiation therapy machine produced by Atomic Energy of Canada Limited (AECL) in 1982 after the Therac-6 and Therac-20 units (the earlier units had been produced in partnership with CGR of France).

It was involved in at least six accidents between 1985 and 1987, in which patients were given massive overdoses of radiation. Because of concurrent programming errors, it sometimes gave its patients radiation doses that were hundreds of times greater than normal, resulting in death or serious injury. These accidents highlighted the dangers of software control of safety-critical systems, and they have become a standard case study in health informatics and software engineering. Additionally the overconfidence of the engineers and lack of proper due diligence to resolve reported software bugs are highlighted as an extreme case where the engineers' overconfidence in their initial work and failure to believe the end users' claims caused drastic repercussions.