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🔗 Transport 🔗 Cycling

The Idaho stop is the common name for laws that allow cyclists to treat a stop sign as a yield sign, and a red light as a stop sign. It first became law in Idaho in 1982, but was not adopted elsewhere until Delaware adopted a limited stop-as-yield law, the "Delaware Yield", in 2017. Arkansas was the second state to legalize both stop-as-yield and red light-as-stop in April 2019. Studies in Delaware and Idaho have shown significant decreases in crashes at stop-controlled intersections.

🔗 Metalworking

Biomachining is the machining process of using lithotropic bacteria to remove material from metal parts, contrasted with chemical machining methods such as chemical milling and physical machining methods such as milling. Certain bacteria, such as Thiobacillus ferrooxidans and Thiobacillus thiooxidans, which are also used in the mineral refinement process of bioleaching, utilize the chemical energy from oxidation of iron or copper to fix carbon dioxide from the air. A metal object, when placed in a culture fluid containing these metal-metabolizing bacteria, will have material removed from its surface over time.

Biomachining is ideal for micromachining due to its very low material removal rate. In addition, biomachining is less likely to leave an undesirable surface finish; neither chemical nor physical energy is concentrated on the cutting area, so the possibility of a damaged or burned surface is slim.

This process has been successfully used to cut both pure iron and pure copper.

🔗 United States 🔗 Biography 🔗 California 🔗 Women scientists 🔗 Biography/science and academia 🔗 Astronomy 🔗 United States/Arizona 🔗 Solar System 🔗 California/California State University

Carolyn Jean Spellmann Shoemaker (June 24, 1929 – August 13, 2021) was an American astronomer and a co-discoverer of Comet Shoemaker–Levy 9. She once held the record for most comets discovered by an individual.

Although Shoemaker earned degrees in history, political science and English literature, she had little interest in science until she met and married geologist Eugene M. ("Gene") Shoemaker in 1950–51. She later said that his explanations of his work thrilled her. Despite her relative inexperience and lack of a science degree, California Institute of Technology (Caltech) had no objection to her joining Gene's team there as a research assistant. She had already shown herself to be unusually patient, and demonstrated exceptional stereoscopic vision, which were particularly valuable qualities for looking for objects in near-Earth space.

🔗 Physics 🔗 Meteorology 🔗 Radio

A whistler is a very low frequency or VLF electromagnetic (radio) wave generated by lightning. Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with a maximum amplitude usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes (mostly intracloud and return-path) where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other. They undergo dispersion of several kHz due to the slower velocity of the lower frequencies through the plasma environments of the ionosphere and magnetosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers categorizes them into Pure Note, Diffuse, 2-Hop, and Echo Train types.

Voyager 1 and 2 spacecraft detected whistler-like activity in the vicinity of Jupiter known as "Jovian Whistlers", implying the presence of lightning there.

🔗 Film 🔗 Military history 🔗 Military history/World War II 🔗 Japan 🔗 Military history/Asian military history 🔗 Military history/Japanese military history 🔗 Film/War films 🔗 Military history/War films 🔗 Anime and manga 🔗 Japan/Japanese cinema 🔗 Anime and manga/Studio Ghibli 🔗 Film/Japanese cinema 🔗 Film/Animated films

Grave of the Fireflies (Japanese: 火垂るの墓, Hepburn: Hotaru no Haka) is a 1988 Japanese animated war drama film written and directed by Isao Takahata, and produced by Studio Ghibli. It is based on the 1967 semi-autobiographical short story Grave of the Fireflies by Akiyuki Nosaka.

The film stars Tsutomu Tatsumi, Ayano Shiraishi, Yoshiko Shinohara and Akemi Yamaguchi. Set in the city of Kobe, Japan, it tells the story of siblings and war orphans Seita and Setsuko, and their desperate struggle to survive during the final months of World War II. Universally acclaimed, Grave of the Fireflies has been ranked as one of the greatest war films of all time and is recognized as a major work of Japanese animation.

🔗 United States 🔗 Mathematics 🔗 Law 🔗 History of Science 🔗 United States/Indiana

The Indiana Pi Bill is the popular name for bill #246 of the 1897 sitting of the Indiana General Assembly, one of the most notorious attempts to establish mathematical truth by legislative fiat. Despite its name, the main result claimed by the bill is a method to square the circle, rather than to establish a certain value for the mathematical constant π, the ratio of the circumference of a circle to its diameter. The bill, written by the crank Edward J. Goodwin, does imply various incorrect values of π, such as 3.2. The bill never became law, due to the intervention of Professor C. A. Waldo of Purdue University, who happened to be present in the legislature on the day it went up for a vote.

The impossibility of squaring the circle using only compass and straightedge constructions, suspected since ancient times, was rigorously proven in 1882 by Ferdinand von Lindemann. Better approximations of π than those implied by the bill have been known since ancient times.

🔗 Physics 🔗 Weather 🔗 Weather/Meteorological instruments and data

The wet-bulb temperature (WBT) is the temperature read by a thermometer covered in water-soaked cloth (a wet-bulb thermometer) over which air is passed. At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature); at lower humidity the wet-bulb temperature is lower than dry-bulb temperature because of evaporative cooling.

The wet-bulb temperature is defined as the temperature of a parcel of air cooled to saturation (100% relative humidity) by the evaporation of water into it, with the latent heat supplied by the parcel. A wet-bulb thermometer indicates a temperature close to the true (thermodynamic) wet-bulb temperature. The wet-bulb temperature is the lowest temperature that can be reached under current ambient conditions by the evaporation of water only.

Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of 32 °C (90 °F), equivalent to a heat index of 55 °C (130 °F). The theoretical limit to human survival for more than a few hours in the shade, even with unlimited water, is a wet-bulb temperature of 35 °C (95 °F) – theoretically equivalent to a heat index of 70 °C (160 °F), though the heat index does not go that high.

🔗 Mathematics

Zero is an even number. In other words, its parity—the quality of an integer being even or odd—is even. This can be easily verified based on the definition of "even": it is an integer multiple of 2, specifically 0 × 2. As a result, zero shares all the properties that characterize even numbers: for example, 0 is neighbored on both sides by odd numbers, any decimal integer has the same parity as its last digit—so, since 10 is even 0 will be even, and if y is even then y + x has the same parity as x—and x and 0 + x always have the same parity.

Zero also fits into the patterns formed by other even numbers. The parity rules of arithmetic, such as even − even = even, require 0 to be even. Zero is the additive identity element of the group of even integers, and it is the starting case from which other even natural numbers are recursively defined. Applications of this recursion from graph theory to computational geometry rely on zero being even. Not only is 0 divisible by 2, it is divisible by every power of 2, which is relevant to the binary numeral system used by computers. In this sense, 0 is the "most even" number of all.

Among the general public, the parity of zero can be a source of confusion. In reaction time experiments, most people are slower to identify 0 as even than 2, 4, 6, or 8. Some students of mathematics—and some teachers—think that zero is odd, or both even and odd, or neither. Researchers in mathematics education propose that these misconceptions can become learning opportunities. Studying equalities like 0 × 2 = 0 can address students' doubts about calling 0 a number and using it in arithmetic. Class discussions can lead students to appreciate the basic principles of mathematical reasoning, such as the importance of definitions. Evaluating the parity of this exceptional number is an early example of a pervasive theme in mathematics: the abstraction of a familiar concept to an unfamiliar setting.

🔗 Military history 🔗 Futures studies 🔗 Military history/Cold War 🔗 Cold War

World War III or the Third World War, often abbreviated as WWIII or WW3, are names given to a hypothetical third worldwide large-scale military conflict after World War I and World War II. The term has been in use since at least as early as 1941. Some apply it loosely to limited or more minor conflicts such as the Cold War or the war on terror. In contrast, others assume that such a conflict would surpass prior world wars in both scope and destructive impact.

Due to the development and use of nuclear weapons near the end of World War II and their subsequent acquisition and deployment by many countries, the potential risk of a nuclear apocalypse causing widespread destruction of Earth's civilization and life is a common theme in speculations about a Third World War. Another primary concern is that biological warfare could cause many casualties. It could happen intentionally or inadvertently, by an accidental release of a biological agent, the unexpected mutation of an agent, or its adaptation to other species after use. Large-scale apocalyptic events like these, caused by advanced technology used for destruction, could render Earth's surface uninhabitable.

Before the beginning of World War II in 1939, World War I (1914–1918) was believed to have been "the war to end [all] wars." It was popularly believed that never again could there possibly be a global conflict of such magnitude. During the interwar period, World War I was typically referred to simply as "The Great War". The outbreak of World War II disproved the hope that humanity might have already "outgrown" the need for such widespread global wars.

With the advent of the Cold War in 1945 and with the spread of nuclear weapons technology to the Soviet Union, the possibility of a third global conflict became more plausible. During the Cold War years, the possibility of a Third World War was anticipated and planned for by military and civil authorities in many countries. Scenarios ranged from conventional warfare to limited or total nuclear warfare. At the height of the Cold War, the doctrine of mutually assured destruction (MAD), which determined an all-out nuclear confrontation would destroy all of the states involved in the conflict, had been developed. The absolute potential destruction of the human race may have contributed to the ability of both American and Soviet leaders to avoid such a scenario.