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🔗 Internet 🔗 Marketing & Advertising

ads.txt (Authorized Digital Sellers) is an initiative from IAB Technology Laboratory. It specifies a text file that companies can host on their web servers, listing the other companies authorized to sell their products or services. This is designed to allow online buyers to check the validity of the sellers from whom they buy, for the purposes of internet fraud prevention.

🔗 Economics

In finance, the rule of 72, the rule of 70 and the rule of 69.3 are methods for estimating an investment's doubling time. The rule number (e.g., 72) is divided by the interest percentage per period (usually years) to obtain the approximate number of periods required for doubling. Although scientific calculators and spreadsheet programs have functions to find the accurate doubling time, the rules are useful for mental calculations and when only a basic calculator is available.

These rules apply to exponential growth and are therefore used for compound interest as opposed to simple interest calculations. They can also be used for decay to obtain a halving time. The choice of number is mostly a matter of preference: 69 is more accurate for continuous compounding, while 72 works well in common interest situations and is more easily divisible. There is a number of variations to the rules that improve accuracy. For periodic compounding, the exact doubling time for an interest rate of r percent per period is

${\displaystyle t={\frac {\ln(2)}{\ln(1+r/100)}}\approx {\frac {72}{r}}}$,

where t is the number of periods required. The formula above can be used for more than calculating the doubling time. If one wants to know the tripling time, for example, replace the constant 2 in the numerator with 3. As another example, if one wants to know the number of periods it takes for the initial value to rise by 50%, replace the constant 2 with 1.5.

🔗 Physics

A Klemperer rosette is a gravitational system of heavier and lighter bodies orbiting in a regular repeating pattern around a common barycenter. It was first described by W. B. Klemperer in 1962, and is a special case of a central configuration.

Klemperer described the system as follows:

Such symmetry is also possessed by a peculiar family of geometrical configurations which may be described as 'rosettes'. In these an even number of 'planets' of two (or more) kinds, one (or some) heavier than the other, but all of each set of equal mass, are placed at the corners of two (or more) interdigitating regular polygons so that the lighter and heavier ones alternate (or follow each other in a cyclic manner).

The simplest rosette would be a series of four alternating heavier and lighter bodies, 90 degrees from one another, in a rhombic configuration [Heavy, Light, Heavy, Light], where the two larger bodies have the same mass, and likewise the two smaller bodies have the same mass. The number of "mass types" can be increased, so long as the arrangement pattern is cyclic: e.g. [ 1,2,3 ... 1,2,3 ], [ 1,2,3,4,5 ... 1,2,3,4,5 ], [ 1,2,3,3,2,1 ... 1,2,3,3,2,1 ], etc.

Klemperer also mentioned octagonal and rhombic rosettes. While all Klemperer rosettes are vulnerable to destabilization, the hexagonal rosette has extra stability because the "planets" sit in each other's L4 and L5 Lagrangian points.

🔗 Software 🔗 Software/Computing 🔗 Norway

Razor 1911 (RZR) is a warez and demogroup founded in Norway, 1986. It was the first ever such group to be initially founded exclusively as a demogroup, before moving into warez in 1987. According to the US Justice Department, Razor 1911 is the oldest software cracking group that is still active on the internet. Razor 1911 ran the diskmag 'Propaganda' until 1995.

🔗 Philosophy 🔗 Philosophy/Aesthetics 🔗 Philosophy/Social and political philosophy 🔗 Philosophy/Philosophy of religion

In a paper delivered to the Aristotelian Society on 12 March 1956, Walter Bryce Gallie (1912–1998) introduced the term essentially contested concept to facilitate an understanding of the different applications or interpretations of the sorts of abstract, qualitative, and evaluative notions—such as "art", "philanthropy" and "social justice"—used in the domains of aesthetics, development, political philosophy, philosophy of history, and philosophy of religion.

Garver (1978) describes their use as follows:

The term essentially contested concepts gives a name to a problematic situation that many people recognize: that in certain kinds of talk there is a variety of meanings employed for key terms in an argument, and there is a feeling that dogmatism ("My answer is right and all others are wrong"), skepticism ("All answers are equally true (or false); everyone has a right to his own truth"), and eclecticism ("Each meaning gives a partial view so the more meanings the better") are none of them the appropriate attitude towards that variety of meanings.

Essentially contested concepts involve widespread agreement on a concept (e.g., "fairness"), but not on the best realization thereof. They are "concepts the proper use of which inevitably involves endless disputes about their proper uses on the part of their users", and these disputes "cannot be settled by appeal to empirical evidence, linguistic usage, or the canons of logic alone".

🔗 Iran 🔗 Architecture 🔗 Food and drink

Yakhchāl (Persian: یخچال‎ "ice pit"; yakh meaning "ice" and chāl meaning "pit") is an ancient type of evaporative cooler. Above ground, the structure had a domed shape, but had a subterranean storage space. It was often used to store ice, but sometimes was used to store food as well. The subterranean space coupled with the thick heat-resistant construction material insulated the storage space year round. These structures were mainly built and used in Persia. Many that were built hundreds of years ago remain standing.

🔗 Libraries 🔗 Belgium

The Universal Decimal Classification (UDC) is a bibliographic and library classification representing the systematic arrangement of all branches of human knowledge organized as a coherent system in which knowledge fields are related and inter-linked. The UDC is an analytico-synthetic and faceted classification system featuring detailed vocabulary and syntax that enables powerful content indexing and information retrieval in large collections. Since 1991, the UDC has been owned and managed by the UDC Consortium, a non-profit international association of publishers with headquarters in The Hague (Netherlands).

Unlike other library classification schemes that have started their life as national systems, the UDC was conceived and maintained as an international scheme. Its translation in world languages started at the beginning of the 20th century and has since been published in various printed editions in over 40 languages. UDC Summary, an abridged Web version of the scheme, is available in over 50 languages. The classification has been modified and extended over the years to cope with increasing output in all areas of human knowledge, and is still under continuous review to take account of new developments.

Albeit originally designed as an indexing and retrieval system, due to its logical structure and scalability, UDC has become one of the most widely used knowledge organization systems in libraries, where it is used for either shelf arrangement, content indexing or both. UDC codes can describe any type of document or object to any desired level of detail. These can include textual documents and other media such as films, video and sound recordings, illustrations, maps as well as realia such as museum objects.

🔗 Medicine 🔗 Medicine/Pulmonology 🔗 Physiology 🔗 Scuba diving 🔗 Physiology/respiratory

Liquid breathing is a form of respiration in which a normally air-breathing organism breathes an oxygen-rich liquid (such as a perfluorocarbon), rather than breathing air.

This requires certain physical properties such as respiratory gas solubility, density, viscosity, vapor pressure, and lipid solubility which some, but not all, perfluorochemicals (perfluorocarbon) have. Thus, it is critical to choose the appropriate PFC for a specific biomedical application, such as liquid ventilation, drug delivery or blood substitutes. The physical properties of PFC liquids vary substantially; however, the one common property is their high solubility for respiratory gases. In fact, these liquids carry more oxygen and carbon dioxide than blood.

In theory, liquid breathing could assist in the treatment of patients with severe pulmonary or cardiac trauma, especially in pediatric cases. Liquid breathing has also been proposed for use in deep diving and space travel. Despite some recent advances in liquid ventilation, a standard mode of application has not yet been established.

🔗 Military history 🔗 Poland 🔗 Military history/World War II 🔗 Scotland 🔗 Zoo

Wojtek (1942 – 2 December 1963; Polish pronunciation: [ˈvɔjtɛk]; in English, sometimes spelled Voytek and pronounced as such) was a Syrian brown bear (Ursus arctos syriacus) bought, as a young cub, at a railway station in Hamadan, Iran, by Polish II Corps soldiers who had been evacuated from the Soviet Union. In order to provide for his rations and transportation, he was eventually enlisted officially as a soldier with the rank of private, and was subsequently promoted to corporal.

He accompanied the bulk of the II Corps to Italy, serving with the 22nd Artillery Supply Company. During the Battle of Monte Cassino, in Italy in 1944, Wojtek helped move crates of ammunition and became a celebrity with visiting Allied generals and statesmen. After the war, mustered out of the Polish Army, he was billeted and lived out the rest of his life at the Edinburgh Zoo in Scotland.