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🔗 United States 🔗 Disaster management 🔗 Crime 🔗 Lists 🔗 Politics 🔗 Schools 🔗 Politics/American politics 🔗 United States/U.S. history 🔗 Politics/Gun politics

This chronological list of school shootings in the United States includes any school shootings that occurred at a K-12 public or private school, as well as at colleges and universities, and on school buses. Excluded from this list are the following:

1. Incidents that occurred during wars
2. Incidents that occurred as a result of police actions
3. Murder-suicides by rejected suitors or estranged spouses
4. Suicides or suicide attempts involving only one person.

Shootings by school staff, where the only victims are other employees, are covered at workplace killings.

🔗 Biology 🔗 Physics 🔗 Biophysics

Magnetosomes are membranous structures present in magnetotactic bacteria (MTB). They contain iron-rich magnetic particles that are enclosed within a lipid bilayer membrane. Each magnetosome can often contain 15 to 20 magnetite crystals that form a chain which acts like a compass needle to orient magnetotactic bacteria in geomagnetic fields, thereby simplifying their search for their preferred microaerophilic environments. Recent research has shown that magnetosomes are invaginations of the inner membrane and not freestanding vesicles. Magnetite-bearing magnetosomes have also been found in eukaryotic magnetotactic algae, with each cell containing several thousand crystals.

Overall, magnetosome crystals have high chemical purity, narrow size ranges, species-specific crystal morphologies and exhibit specific arrangements within the cell. These features indicate that the formation of magnetosomes is under precise biological control and is mediated biomineralization.

Magnetotactic bacteria usually mineralize either iron oxide magnetosomes, which contain crystals of magnetite (Fe₃O₄), or iron sulfide magnetosomes, which contain crystals of greigite (Fe₃S₄). Several other iron sulfide minerals have also been identified in iron sulfide magnetosomes—including mackinawite (tetragonal FeS) and a cubic FeS—which are thought to be precursors of Fe₃S₄. One type of magnetotactic bacterium present at the oxic-anoxic transition zone (OATZ) of the southern basin of the Pettaquamscutt River Estuary, Narragansett, Rhode Island, United States is known to produce both iron oxide and iron sulfide magnetosomes.

🔗 Iran 🔗 Cities

Ramsar (Persian: رامسر, also Romanized as Rámsar and Ránsar; formerly, Sakht Sar) is the capital of Ramsar County, Mazandaran Province, Iran. In 2012 its population was 33,018, in 9,421 families.

Ramsar lies on the coast of the Caspian Sea. It was also known as Sakhtsar in the past. The climate of Ramsar is hot and humid in summer and mild in winter. The proximity of the forest and the sea in this city has given a special beauty to this city and this attracts tourists in all seasons. Ramsar has an airport. The city of Ramsar was a small village in western Mazandaran until the Qajar period, and during the first Pahlavi period, with the rule of Reza Shah and with the support of the government, it became a beautiful city with many tourist facilities.

Ramsar is the westernmost county and city in Mazandaran. It borders the Caspian Sea to the north, Gilan province to the west, Qazvin Province to the south, and Tonekabon to the east.

🔗 New York City 🔗 Engineering

The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months. The building, now known as Citigroup Center, occupied an entire block and was to be the headquarters of Citibank. Its structure, designed by William LeMessurier, had several unusual design features, including a raised base supported by four offset stilts, and diagonal bracing which absorbed wind loads from upper stories.

In the original design, potential wind loads for the building were calculated incorrectly. The flaw was discovered by Diane Hartley, an undergraduate student at Princeton University who was writing a thesis on the building, and was communicated to the firm responsible for the structural design. LeMessurier was subsequently lauded for acknowledging his error and orchestrating a successful repair effort. Estimates at the time suggested that the building could be toppled by a 70-mile-per-hour (110 km/h) wind, with possibly many people killed as a result. The crisis was kept secret until 1995 and Hartley had no knowledge of the significance of her work until after that time.

🔗 Technology 🔗 Medicine

The Corsi–Rosenthal Box, also called a Corsi–Rosenthal Cube or a Comparetto Cube, is a design for a do-it-yourself air purifier that can be built comparatively inexpensively. It was designed during the COVID-19 pandemic with the goal of reducing the levels of airborne viral particles in indoor settings.

🔗 Computing

QB64 (originally QB32) is a self-hosting BASIC compiler for Microsoft Windows, Linux and Mac OS X, designed to be compatible with Microsoft QBasic and QuickBASIC. QB64 is a C++ emitter, which is integrated with a C++ compiler to provide compilation via C++ code and GCC optimization.

QB64 implements most QBasic statements, and can run many QBasic programs, including Microsoft's QBasic Gorillas and Nibbles games. Furthermore, QB64 has been designed to contain an IDE resembling the QBASIC IDE. QB64 also extends the QBASIC programming language to include 64-bit data types, as well as better sound and graphics support. It can also emulate some DOS/x86 specific features such as INT 33h mouse access, and multiple timers.

Since version 2.0, QB64 now offers debugging abilities, with the new $DEBUG metacommand.

🔗 Economics 🔗 Lists

This is a list of some of the major unsolved problems, puzzles, or questions in economics. Some of these are theoretical in origin and some of them concern the inability of orthodox economic theory to explain an empirical observation.

🔗 International relations 🔗 Lists 🔗 Countries

This is a list of purchases of territory by a sovereign nation from another sovereign nation.

🔗 Film 🔗 Film/Filmmaking

Soundies are three-minute American musical films, produced between 1940 and 1947, each displaying a song, dance, and/or band or orchestral number. Produced professionally on 35 mm black-and-white film, like theatrical motion pictures, they were printed on the more portable and economical 16 mm film.

The films were shown in a coin-operated "movie jukebox" named the Panoram, manufactured by the Mills Novelty Company of Chicago. Each Panoram housed a 16 mm RCA film projector, with eight Soundies films threaded in an endless-loop arrangement. A system of mirrors flashed the image from the lower half of the cabinet onto a front-facing screen in the top half. Each film cost 10 cents to play, with no choice of song; the patron saw whatever film was next in the queue. Panorams could be found in public amusement centers, nightclubs, taverns, restaurants, and factory lounges, and the films were changed weekly. The completed Soundies were generally made available within a few weeks of their filming, by the Soundies Distributing Corporation of America.

Several production companies filmed the Soundies shorts in New York City, Hollywood, and Chicago: James Roosevelt's Globe Productions (1940–41), Cinemasters (1940–41), Minoco Productions (owned by Mills Novelty, 1941–43), RCM Productions (1941–46), LOL Productions (1943), Glamourettes (1943), Filmcraft Productions (1943–46), and Alexander Productions (1946) led by William D. Alexander). The performers recorded the music in advance, and mimed to the soundtrack during filming.

The movie-jukebox idea developed several imitations and variations of the technical design; the most successful of these imitators were the Techniprocess company (managed by Rudy Vallee) and the Featurettes company, which used original novelty songs and usually unknown talent (17-year-old Gwen Verdon appears in a couple of the Featurettes as "Gwen Verdun"). As Soundies quickly gained most of the market for jukebox films, the other companies disbanded, and some sold their films to the Soundies concern.