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πŸ”— Gallery of animations that explain math ideas

Below is a mostly comprehensive gallery of all images β€” illustrations, diagrams and animations β€” that I have created for Wikipedia over the years, some of which have been selected as featured pictures, or even picture of the day. As you'll probably notice, they're mostly related to physics and mathematics, which are my main areas of interest.

If you have any comments, requests, suggestions or corrections, feel free to drop me a message on my talk page. But please, before making a suggestion, first take a look and see what sort of stuff I can do. Due to time, knowledge and complexity constraints, I cannot guarantee I'll be able to make a good illustration of any topic.

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πŸ”— Before Present

πŸ”— Time πŸ”— Geology

Before Present (BP) years is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred in the past. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale, reflecting the origin of practical radiocarbon dating in the 1950s. The abbreviation "BP" has been interpreted retrospectively as "Before Physics"; that refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, making dating after that time likely to be unreliable.

In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation RCYBP is explicitly Radio Carbon Years Before Present.

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πŸ”— The lifetime tooth decay vaccine is now available (in Honduras)

πŸ”— Pharmacology πŸ”— Dentistry

A caries vaccine is a vaccine to prevent and protect against tooth decay. Streptococcus mutans (S. mutans) has been identified as the major etiological agent of human dental caries. The development of a vaccine for tooth decay has been under investigation since the 1970s. In 1972, a caries vaccine was said to be in animal testing in England, and that it would have begun human testing soon. However, intrinsic difficulties in developing it, coupled with lack of strong economic interests, are the reasons why still no such vaccine is commercially available today. Several types of vaccines are being developed at research centres, with some kind of caries vaccines being considered to diminish or prevent dental caries' impact on young people.

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πŸ”— McCollough effect

πŸ”— Psychology

The McCollough effect is a phenomenon of human visual perception in which colorless gratings appear colored contingent on the orientation of the gratings. It is an aftereffect requiring a period of induction to produce it. For example, if someone alternately looks at a red horizontal grating and a green vertical grating for a few minutes, a black-and-white horizontal grating will then look greenish and a black-and-white vertical grating will then look pinkish. The effect is remarkable because, where time-elapse testing is employed, it has been reported to last up to 2.8 months.

The effect was discovered by American psychologist Celeste McCollough in 1965.

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πŸ”— Jonathan James

πŸ”— Biography πŸ”— Law πŸ”— Computer Security πŸ”— Computer Security/Computing πŸ”— Biography/science and academia πŸ”— Florida

Jonathan Joseph James (December 12, 1983 – May 18, 2008) was an American hacker who was the first juvenile incarcerated for cybercrime in the United States. The South Florida native was 15 years old at the time of the first offense and 16 years old on the date of his sentencing. He died at his Pinecrest, Florida home on May 18, 2008, of a self-inflicted gunshot wound.

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πŸ”— Low-Background Steel

πŸ”— Metalworking πŸ”— Materials

Low-background steel is any steel produced prior to the detonation of the first nuclear bombs in the 1940s and 1950s. With the Trinity test and the nuclear bombings of Hiroshima and Nagasaki in 1945, and then subsequent nuclear weapons testing during the early years of the Cold War, background radiation levels increased across the world. Modern steel is contaminated with radionuclides because its production uses atmospheric air. Low-background steel is so-called because it does not suffer from such nuclear contamination. This steel is used in devices that require the highest sensitivity for detecting radionuclides.

The primary source of low-background steel is ships that were constructed before the Trinity test, most famously the scuttled German World War I warships in Scapa Flow.

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πŸ”— Russian Web Brigades

πŸ”— Espionage πŸ”— Internet πŸ”— Russia πŸ”— Russia/mass media in Russia πŸ”— Russia/Russian, Soviet, and CIS military history πŸ”— Russia/politics and law of Russia

Russian web brigades, also called Russian trolls, Russian bots, or more recently Kremlin Bots (after the Kremlin in Moscow) / Kremlins (a pejorative allusion to Gremlin) are state-sponsored anonymous Internet political commentators and trolls linked to the Government of Russia. Participants report that they are organized into teams and groups of commentators that participate in Russian and international political blogs and Internet forums using sockpuppets, social bots and large-scale orchestrated trolling and disinformation campaigns to promote pro-Putin and pro-Russian propaganda. Articles on the Russian Wikipedia concerning the MH17 crash and the 2014 Ukraine conflict were targeted by Russian internet propaganda outlets.

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πŸ”— Kaktovik numerals – A base-20 number system that is visually easy too

πŸ”— Numbers πŸ”— Canada πŸ”— Arctic πŸ”— Writing systems πŸ”— Indigenous peoples of North America πŸ”— Canada/Canadian Territories πŸ”— Alaska

Kaktovik numerals are a featural positional numeral system created by Alaskan IΓ±upiat.

Arabic numeral notation, which was designed for a base-10 numeral system, is inadequate for the Inuit languages, which use a base-20 numeral system. Students in Kaktovik, Alaska, invented a base-20 numeral notation in 1994 to rectify this issue, and this system spread among the Alaskan IΓ±upiat and has been considered in other countries where Inuit languages are spoken.

The image at right shows the digits 0 to 19. Twenty is written as a one and a zero (\Ι€), forty as a two and a zero (VΙ€), four hundred as a one and two zeros (\Ι€Ι€), eight hundred as a two and two zeros (VΙ€Ι€), etc.

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πŸ”— Human Accelerated Region 1

πŸ”— Molecular Biology πŸ”— Molecular Biology/Genetics

In molecular biology, Human Accelerated Region 1 (Highly Accelerated Region 1, HAR1) is a segment of the human genome found on the long arm of chromosome 20. It is a human accelerated region. It is located within a pair of overlapping long non-coding RNA genes, HAR1A (HAR1F) and HAR1B (HAR1R).

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πŸ”— Normally distributed and uncorrelated does not imply independent

πŸ”— Statistics

In probability theory, although simple examples illustrate that linear uncorrelatedness of two random variables does not in general imply their independence, it is sometimes mistakenly thought that it does imply that when the two random variables are normally distributed. This article demonstrates that assumption of normal distributions does not have that consequence, although the multivariate normal distribution, including the bivariate normal distribution, does.

To say that the pair ( X , Y ) {\displaystyle (X,Y)} of random variables has a bivariate normal distribution means that every linear combination a X + b Y {\displaystyle aX+bY} of X {\displaystyle X} and Y {\displaystyle Y} for constant (i.e. not random) coefficients a {\displaystyle a} and b {\displaystyle b} has a univariate normal distribution. In that case, if X {\displaystyle X} and Y {\displaystyle Y} are uncorrelated then they are independent. However, it is possible for two random variables X {\displaystyle X} and Y {\displaystyle Y} to be so distributed jointly that each one alone is marginally normally distributed, and they are uncorrelated, but they are not independent; examples are given below.

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