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🔗 Mathematics

A tautochrone or isochrone curve (from Greek prefixes tauto- meaning same or iso- equal, and chrono time) is the curve for which the time taken by an object sliding without friction in uniform gravity to its lowest point is independent of its starting point on the curve. The curve is a cycloid, and the time is equal to π times the square root of the radius (of the circle which generates the cycloid) over the acceleration of gravity. The tautochrone curve is related to the brachistochrone curve, which is also a cycloid.

🔗 Computing

Unlambda is a minimal, "nearly pure" functional programming language invented by David Madore. It is based on combinatory logic, an expression system without the lambda operator or free variables. It relies mainly on two built-in functions (s and k) and an apply operator (written `, the backquote character). These alone make it Turing-complete, but there are also some input/output (I/O) functions to enable interacting with the user, some shortcut functions, and a lazy evaluation function. Variables are unsupported.

Unlambda is free and open-source software distributed under a GNU General Public License (GPL) 2.0 or later.

🔗 Medicine 🔗 Health and fitness

The protein leverage hypothesis states that human beings will prioritize the consumption of protein in food over other dietary components, and will eat until protein needs have been met, regardless of energy content, thus leading to over-consumption of foodstuffs when their protein content is low.

This hypothesis has been put forward as a potential explanation of the obesity epidemic. Empirical tests have provided some evidence to confirm the hypothesis with one study suggesting that this could be a link between ultra-processed foods and the prevalence of obesity in the developed world.

In the 1980s, David Raubenheimer and Stephen Simpson, researchers now at the University of Sydney, began to study appetite and food intake in locusts. By studying responses to artificial diets with differing compositions of protein and carbohydrate, they developed the protein leverage hypothesis. Their experiments showed that those who aren't getting enough protein in their diet will continue to be hungry, even when their overall caloric intake is high. "Protein decoys", such as ultraprocessed savory foods that contain little protein (e.g., barbecue chips), are likely to be attractive and to result in overeating. The hormone FGF21, which is released from the liver, can drive savory-seeking behavior under conditions of low protein intake. However, extremely high protein diets can also have drawbacks. In 2020 Simpson and Raubenheimer published the popular science book Eat Like the Animals: What Nature Teaches Us about the Science of Healthy Eating, which details their experiments. For lifelong health they recommend eating a balanced diet with more fiber and fewer fats and carbohydrates rather than an extremely high protein diet.

In 1995, Australian researcher Susanna Holt developed the concept of satiety value, a measure of how much a given food is likely to satisfy the hunger of someone. High protein foods have been found to have high satiety values, though these are outmatched by potatoes and oats (which have a low glycemic index). Fruits rank similarly to high protein foods (likely due to their high level of dietary fibre).

🔗 France

La Bougie du Sapeur (French: [la bu.ʒi dy sa.pœʁ]) is a French satirical newspaper launched in 1980 that is published only on Leap Day, making it the world's least frequently published newspaper. The editor-in-chief is Jean d'Indy, who works for France Galop and has been involved in producing the paper since 1992.

🔗 Economics

"The Market for Lemons: Quality Uncertainty and the Market Mechanism" is a well-known 1970 paper by economist George Akerlof which examines how the quality of goods traded in a market can degrade in the presence of information asymmetry between buyers and sellers, leaving only "lemons" behind. In American slang, a lemon is a car that is found to be defective after it has been bought.

Suppose buyers cannot distinguish between a high-quality car (a "peach") and a "lemon". Then they are only willing to pay a fixed price for a car that averages the value of a "peach" and "lemon" together (p_avg). But sellers know whether they hold a peach or a lemon. Given the fixed price at which buyers will buy, sellers will sell only when they hold "lemons" (since p_lemon < p_avg) and they will leave the market when they hold "peaches" (since p_peach > p_avg). Eventually, as enough sellers of "peaches" leave the market, the average willingness-to-pay of buyers will decrease (since the average quality of cars on the market decreased), leading to even more sellers of high-quality cars to leave the market through a positive feedback loop.

Thus the uninformed buyer's price creates an adverse selection problem that drives the high-quality cars from the market. Adverse selection is a market mechanism that can lead to a market collapse.

Akerlof's paper shows how prices can determine the quality of goods traded on the market. Low prices drive away sellers of high-quality goods, leaving only lemons behind. In 2001, Akerlof, along with Michael Spence, and Joseph Stiglitz, jointly received the Nobel Memorial Prize in Economic Sciences, for their research on issues related to asymmetric information.

🔗 Psychology 🔗 Education

Bloom's taxonomy is a set of three hierarchical models used to classify educational learning objectives into levels of complexity and specificity. The three lists cover the learning objectives in cognitive, affective and sensory domains. The cognitive domain list has been the primary focus of most traditional education and is frequently used to structure curriculum learning objectives, assessments and activities.

The models were named after Benjamin Bloom, who chaired the committee of educators that devised the taxonomy. He also edited the first volume of the standard text, Taxonomy of Educational Objectives: The Classification of Educational Goals.

🔗 Economics

The Alchian–Allen effect was described in 1964 by Armen Alchian and William R Allen in the book University Economics (now called Exchange and Production). It states that when the prices of two substitute goods, such as high and low grades of the same product, are both increased by a fixed per-unit amount such as a transportation cost or a lump-sum tax, consumption will shift toward the higher-grade product. This is because the added per-unit amount decreases the relative price of the higher-grade product.

Suppose, for example, that high-grade coffee beans are $3/pound and low-grade beans $1.50/pound; in this example, high-grade beans cost twice as much as low-grade beans. Now add a per-pound international shipping cost of $1. The effective prices are now $4 and $2.50; high-grade beans now cost only 1.6 times as much as low-grade beans. This reduced ratio of difference will induce distant coffee-buyers to now choose a higher ratio of high-to-low grade beans than local coffee-buyers.

The effect has been studied as it applies to illegal drugs and it has been shown that the potency of marijuana increased in response to higher enforcement budgets, and there was a similar effect for alcohol in the U.S. during Prohibition. This effect is called iron law of prohibition.

Another example is that Australians drink higher-quality Californian wine than Californians, and vice versa, because it is only worth the transportation costs for the most expensive wine.

Colloquially, the Alchian–Allen theorem is also known as the “shipping the good apples out” theorem (Thomas Borcherding), or as the “third law of demand.”

🔗 Germany 🔗 Architecture 🔗 Poland

Drzymała's wagon (Polish: wóz Drzymały) was a house on wheels built by Michał Drzymała as a protest against Imperial Germany's policy of Germanization in its Polish territories. Its owner, the peasant Michał Drzymała (1857-1937), was not only able to circumvent German building regulations by moving his home every day, but with his wagon-home became a Polish folk hero during the Partitions of Poland.

In 1886, by resolution of the Prussian Landtag, a Settlement Commission had been established to encourage German settlement in the Province of Posen and West Prussia. The Commission was empowered to purchase vacant property of the Polish szlachta and sell it to approved German applicants. The Prussian government regarded this as a measure designed to counteract the German "Flight from the East" (Ostflucht) and reduce the number of Poles, who were migrating to the area in hundreds of thousands looking for work. In Polish eyes, the establishment of the Commission was an aggressive measure designed to drive Poles from their lands.

While the campaign against Polish landownership largely missed its aims, it produced a strong opposition with its own hero, Drzymała. In 1904 he purchased a plot of land in Pogradowitz in the Posen district of Bomst, but found that the newly implemented Prussian Feuerstättengesetz ("furnace law") enabled local officials to deny him as a Pole the permission to build a permanent dwelling with an oven on his land. The law considered any place of stay a house if it stayed in one place for more than 24 hours. To get around the rule, he set himself up in a former circus caravan and for several years tenaciously defied in the courts all attempts to remove him. Each day, Drzymała moved the wagon a short distance, thereby exploiting the loophole and avoiding any legal penalties, until in 1909 he was able to buy an existent farmhouse nearby.

The case attracted publicity all over Germany. The German Kulturkampf measures and the Colonization Commission ultimately succeeded in stimulating the Polish national sentiment that they had been designed to suppress.

🔗 Biography 🔗 Soviet Union 🔗 Russia 🔗 Biography/sports and games 🔗 Russia/sports and games in Russia 🔗 Armenia 🔗 Underwater diving 🔗 Swimming

Shavarsh Vladimiri (Vladimirovich) Karapetyan (Armenian: Շավարշ Կարապետյան; born May 19, 1953) is a retired former Soviet finswimmer, best known for saving the lives of 20 people in a 1976 incident in Yerevan.