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🔗 Spaceflight 🔗 Physics

A Van Allen radiation belt is a zone of energetic charged particles, most of which originate from the solar wind, that are captured by and held around a planet by that planet's magnetic field. Earth has two such belts and sometimes others may be temporarily created. The discovery of the belts is credited to James Van Allen, and as a result, Earth's belts are known as the Van Allen belts. Earth's two main belts extend from an altitude of about 640 to 58,000 km (400 to 36,040 mi) above the surface in which region radiation levels vary. Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction.

The belts are located in the inner region of Earth's magnetosphere. The belts trap energetic electrons and protons. Other nuclei, such as alpha particles, are less prevalent. The belts endanger satellites, which must have their sensitive components protected with adequate shielding if they spend significant time near that zone. In 2013, NASA reported that the Van Allen Probes had discovered a transient, third radiation belt, which was observed for four weeks until it was destroyed by a powerful, interplanetary shock wave from the Sun.

🔗 Astronomy 🔗 Geology

The Eltanin impact is thought to be an asteroid impact in the eastern part of the South Pacific Ocean during the Pliocene-Pleistocene boundary around 2.51 ± 0.07  million years ago. The location was at the edge of the Bellingshausen Sea 1,500 km (950 mi) southwest of Chile. The asteroid was estimated to be about one to four km (0.6 to 2.5 mi) in diameter and the impact would have left a crater approximately 35 km (22 mi) across.

🔗 Algae

Valonia ventricosa, also known as bubble algae or sailor's eyeballs is a species of alga found in oceans throughout the world in tropical and subtropical regions. It is one of the largest – if not the largest – unicellular organisms.

🔗 Medicine 🔗 Psychology 🔗 Linguistics 🔗 Linguistics/Applied Linguistics 🔗 Education

Spaced repetition is an evidence-based learning technique that is usually performed with flashcards. Newly introduced and more difficult flashcards are shown more frequently while older and less difficult flashcards are shown less frequently in order to exploit the psychological spacing effect. The use of spaced repetition has been shown to increase rate of learning.

Although the principle is useful in many contexts, spaced repetition is commonly applied in contexts in which a learner must acquire many items and retain them indefinitely in memory. It is, therefore, well suited for the problem of vocabulary acquisition in the course of second-language learning. A number of spaced repetition software programs have been developed to aid the learning process. Alternative names for spaced repetition include spaced rehearsal, expanding rehearsal, graduated intervals, repetition spacing, repetition scheduling, spaced retrieval and expanded retrieval.

Vital articles are lists of subjects for which the English Wikipedia should have corresponding featured-class articles. They serve as centralized watchlists to track the status of Wikipedia's most important articles. The very most important articles are in Level 1.

This page constitutes Level 3 of the vital articles list and includes approximately 1,000 articles. All articles from higher levels are also included in lower levels. For example, all 100 subjects on the Level 2 list (shown on this page in bold font) are included here in Level 3. And the Level 2 list also includes the 10 subjects on Level 1 (shown on this page in bold italics). A larger Level 4 list of 10,000 articles also exists, and a Level 5 list of 50,000 articles is in the process of being created.

Articles are labelled as:

These symbols and article counts are updated daily by User:cewbot.

• The bot only update counter with the pattern "(000 articles)" in section title.
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This list is tailored to the English-language Wikipedia. There is also a list of one thousand articles considered vital to Wikipedias of all languages, as well as Vital Article lists tailored to different Wikipedia languages accessible via the languages sidebar.

Articles should not be added or removed from this list without a consensus on the talk page. For more information on this list and the process for adding or removing articles, please see the Frequently Asked Questions (FAQ) page.

🔗 Insects 🔗 Diptera

Toxorhynchites, also called elephant mosquito or mosquito eater, is a genus of diurnal and often relatively colorful mosquitoes, found worldwide between about 35° north and 35° south. It includes the largest known species of mosquito, at up to 18 mm (0.71 in) in length and 24 mm (0.94 in) in wingspan. It is among the many kinds of mosquito that do not consume blood. The adults subsist on carbohydrate-rich materials, such as honeydew, or saps and juices from damaged plants, refuse, fruit, and nectar.

Their larvae prey on the larvae of other mosquitoes and similar nektonic prey, making Toxorhynchites beneficial to humans. In this respect, they contrast with blood-sucking species of mosquitoes. Toxorhynchites larvae live on a protein- and fat-rich diet of aquatic animals such as mosquito larvae. They have no need to risk their lives sucking blood in adulthood, having already accumulated the necessary materials for oogenesis and vitellogenesis.

Most species occur in forests. The larvae of one jungle variety, Toxorhynchites splendens, consume larvae of other mosquito species occurring in tree crevices, particularly Aedes aegypti.

Unlike Toxorhynchites mosquitoes, detritus feeder mosquito female larvae rely on blood meals to produce eggs more plentifully than a diet of nectar would permit. And even though blood sucking is a risky strategy that entails more casualties, and they could in principle subsist on nectar and the like as their males generally do, the risk is outweighed on average by the increase in the number and size of yolk-rich eggs that such protein-rich food permit.

Environmental scientists have suggested that Toxorhynchites mosquitoes be introduced to areas outside their natural range in order to fight dengue fever. This has been practiced historically, but errors have been made. For example, when intending to introduce T. splendens to new areas, scientists actually introduced T. amboinensis. An extinct species is known from Miocene aged Mexican Amber

🔗 California 🔗 Companies 🔗 California/San Francisco Bay Area 🔗 Internet 🔗 Food and drink

Webvan was a dot-com company and grocery business that filed for bankruptcy in 2001 after 3 years of operation. It was headquartered in Foster City, California, United States. It delivered products to customers' homes within a 30-minute window of their choosing. At its peak, it offered service in ten US markets: the San Francisco Bay Area; Dallas; Sacramento; San Diego; Los Angeles; Orange County, California; Chicago; Seattle; Portland, Oregon; and Atlanta, Georgia. The company had hoped to expand to 26 cities by 2001.

🔗 Germany 🔗 Law Enforcement 🔗 Typography

The FE-Schrift or Fälschungserschwerende Schrift (forgery-impeding typeface) is a sans serif typeface introduced for use on licence plates. Its monospaced letters and numbers are slightly disproportionate to prevent easy modification and to improve machine readability. It has been developed in Germany where it has been mandatory since November 2000.

The abbreviation "FE" is derived from the compound German adjective "fälschungserschwerend" combining the noun "Fälschung" (falsification) and the verb "erschweren" (to hinder). "Schrift" means font in German. Other countries have later introduced the same or a derived typeface for license plates taking advantage of the proven design for the FE-Schrift.

🔗 Climate change 🔗 Environment 🔗 Plants 🔗 Arctic 🔗 Palaeontology 🔗 Geology

The Azolla event is a scenario hypothesized to have occurred in the middle Eocene epoch, around 49 million years ago, when blooms of the freshwater fern Azolla are thought to have happened in the Arctic Ocean. As they sank to the stagnant sea floor, they were incorporated into the sediment; the resulting draw-down of carbon dioxide has been speculated to have helped transform the planet from a "greenhouse Earth" state, hot enough for turtles and palm trees to prosper at the poles, to the current icehouse Earth known as the Late Cenozoic Ice Age.

🔗 Environment 🔗 Disaster management 🔗 London 🔗 Ecology 🔗 River Thames

The Great Stink was an event in central London in July and August 1858 during which the hot weather exacerbated the smell of untreated human waste and industrial effluent that was present on the banks of the River Thames. The problem had been mounting for some years, with an ageing and inadequate sewer system that emptied directly into the Thames. The miasma from the effluent was thought to transmit contagious diseases, and three outbreaks of cholera before the Great Stink were blamed on the ongoing problems with the river.

The smell, and fears of its possible effects, prompted action from the local and national administrators who had been considering possible solutions for the problem. The authorities accepted a proposal from the civil engineer Joseph Bazalgette to move the effluent eastwards along a series of interconnecting sewers that sloped towards outfalls beyond the metropolitan area. Work on high-, mid- and low-level systems for the new Northern and Southern Outfall Sewers started at the beginning of 1859 and lasted until 1875. To aid the drainage, pumping stations were placed to lift the sewage from lower levels into higher pipes. Two of the more ornate stations, Abbey Mills in Stratford and Crossness on the Erith Marshes, are listed for protection by English Heritage. Bazalgette's plan introduced the three embankments to London in which the sewers ran—the Victoria, Chelsea and Albert Embankments.

Bazalgette's work ensured that sewage was no longer dumped onto the shores of the Thames and brought an end to the cholera outbreaks; his actions are thought to have saved more lives than the efforts of any other Victorian official. His sewer system operates into the 21st century, servicing a city that has grown to a population of over eight million. The historian Peter Ackroyd argues that Bazalgette should be considered a hero of London.