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🔗 Automobiles

The Dymaxion car was designed by American inventor Buckminster Fuller during the Great Depression and featured prominently at Chicago's 1933/1934 World's Fair. Fuller built three experimental prototypes with naval architect Starling Burgess – using donated money as well as a family inheritance – to explore not an automobile per se, but the 'ground-taxiing phase' of a vehicle that might one day be designed to fly, land and drive – an "Omni-Medium Transport". Fuller associated the word Dymaxion with much of his work, a portmanteau of the words dynamic, maximum, and tension, to summarize his goal to do more with less.

The Dymaxion's aerodynamic bodywork was designed for increased fuel efficiency and top speed, and its platform featured a lightweight hinged chassis, rear-mounted V8 engine, front-wheel drive (a rare RF layout), and three wheels. With steering via its third wheel at the rear (capable of 90° steering lock), the vehicle could steer itself in a tight circle, often causing a sensation. Fuller noted severe limitations in its handling, especially at high speed or in high wind, due to its rear-wheel steering (highly unsuitable for anything but low speeds) and the limited understanding of the effects of lift and turbulence on automobile bodies in that era – allowing only trained staff to drive the car and saying it "was an invention that could not be made available to the general public without considerable improvements." Shortly after its launch, a prototype crashed and killed the Dymaxion's driver.

Despite courting publicity and the interest of auto manufacturers, Fuller used his inheritance to finish the second and third prototypes, selling all three, dissolving Dymaxion Corporation and reiterating that the Dymaxion was never intended as a commercial venture. One of the three original prototypes survives, and two semi-faithful replicas have recently been constructed. The Dymaxion was included in the 2009 book Fifty Cars That Changed The World and was the subject of the 2012 documentary The Last Dymaxion.

In 2008, The New York Times said Fuller "saw the Dymaxion, as he saw much of the world, as a kind of provisional prototype, a mere sketch, of the glorious, eventual future."

🔗 Greece 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Greece/Byzantine world 🔗 Textile Arts

In the mid-6th century CE, two monks, with the support of the Byzantine emperor Justinian I, acquired and smuggled living silkworms into the Byzantine Empire, which led to the establishment of an indigenous Byzantine silk industry that long held a silk monopoly in Europe.

🔗 Computing 🔗 Computing/Software

Scheme 48 is a programming language, a dialect of the language Scheme, an implementation using an interpreter which emits bytecode. It has a foreign function interface for calling functions from the language C and comes with a library for regular expressions (regex), and an interface for Portable Operating System Interface (POSIX). It is supported by the portable Scheme library SLIB, and is the basis for the Scheme shell Scsh. It has been used in academic research. It is free and open-source software released under a BSD license.

It is called "Scheme 48" because the first version was written in 48 hours in August 1986. The authors now say it is intended to be understood in 48 hours.

🔗 Classical music 🔗 Classical music/Compositions

Leck mich im Arsch ('Kiss my arse!', or literally 'Lick me in the arse') is a canon in B-flat major composed by Wolfgang Amadeus Mozart, K. 231 (K. 382c), with lyrics in German. It was one of a set of at least six canons probably written in Vienna in 1782. Sung by six voices as a three-part round, it is thought to be a party piece for his friends. The main theme is derived from the final movement of Joseph Haydn's Symphony No. 3 in G-Major.

🔗 Italy 🔗 Geography

The Aosta Valley (Italian: Valle d'Aosta [ˈvalle daˈɔsta] (official) or Val d'Aosta (usual); French: Vallée d'Aoste; Arpitan: Val d'Outa; Walser: Augschtalann or Ougstalland; Piedmontese: Val d'Osta) is a mountainous autonomous region in northwestern Italy. It is bordered by Auvergne-Rhône-Alpes, France, to the west, Valais, Switzerland, to the north, and by Piedmont, Italy, to the south and east. The regional capital is Aosta.

Covering an area of 3,263 km² (1,260 sq mi) and with a population of about 128,000 it is the smallest, least populous, and least densely populated region of Italy. The province of Aosta having been dissolved in 1945, the Aosta Valley region was the first region of Italy to abolish provincial subdivisions. Provincial administrative functions are provided by the regional government. The region is divided into 74 comuni (French: communes).

Italian and French are the official languages, though the native population also speak Valdôtain, a dialect of Franco-Provençal. Italian is spoken as a mother tongue by 77.29% of population, Valdôtain by 17.91%, and French by 1.25%. In 2009, reportedly 50.53% of the population could speak all three languages.

🔗 Europe 🔗 Middle Ages 🔗 Middle Ages/History

An erdstall is a type of tunnel found across Europe. They are of unknown origin but are believed to date from the Middle Ages. A variety of purposes have been theorized, including that they were used as escape routes or hiding places, but the most prominent theory is that they served a religious or spiritual purpose.

🔗 Microbiology

Cable bacteria are filamentous bacteria that conduct electricity across distances over 1 cm in sediment and groundwater aquifers. Cable bacteria allow for long distance electron transport, which connects electron donors to electron acceptors, connecting previously separated oxidation and reduction reactions. Cable bacteria couple the reduction of oxygen or nitrate at the sediment's surface to the oxidation of sulfide in the deeper, anoxic, sediment layers.

🔗 International relations 🔗 Lists 🔗 Countries

This is a list of purchases of territory by a sovereign nation from another sovereign nation.

🔗 Psychology

In psychology, the four stages of competence, or the "conscious competence" learning model, relates to the psychological states involved in the process of progressing from incompetence to competence in a skill. People may have several skills, some unrelated to each other, and each skill will typically be at one of the stages at a given time. Many skills require practice to remain at a high level of competence.

The four stages suggest that individuals are initially unaware of how little they know, or unconscious of their incompetence. As they recognize their incompetence, they consciously acquire a skill, then consciously use it. Eventually, the skill can be utilized without it being consciously thought through: the individual is said to have then acquired unconscious competence.

🔗 Mathematics

Hilbert's twenty-fourth problem is a mathematical problem that was not published as part of the list of 23 problems known as Hilbert's problems but was included in David Hilbert's original notes. The problem asks for a criterion of simplicity in mathematical proofs and the development of a proof theory with the power to prove that a given proof is the simplest possible.

The 24th problem was rediscovered by German historian Rüdiger Thiele in 2000, noting that Hilbert did not include the 24th problem in the lecture presenting Hilbert's problems or any published texts. Hilbert's friends and fellow mathematicians Adolf Hurwitz and Hermann Minkowski were closely involved in the project but did not have any knowledge of this problem.

This is the full text from Hilbert's notes given in Rüdiger Thiele's paper. The section was translated by Rüdiger Thiele.

The 24th problem in my Paris lecture was to be: Criteria of simplicity, or proof of the greatest simplicity of certain proofs. Develop a theory of the method of proof in mathematics in general. Under a given set of conditions there can be but one simplest proof. Quite generally, if there are two proofs for a theorem, you must keep going until you have derived each from the other, or until it becomes quite evident what variant conditions (and aids) have been used in the two proofs. Given two routes, it is not right to take either of these two or to look for a third; it is necessary to investigate the area lying between the two routes. Attempts at judging the simplicity of a proof are in my examination of syzygies and syzygies [Hilbert misspelled the word syzygies] between syzygies (see Hilbert 42, lectures XXXII–XXXIX). The use or the knowledge of a syzygy simplifies in an essential way a proof that a certain identity is true. Because any process of addition [is] an application of the commutative law of addition etc. [and because] this always corresponds to geometric theorems or logical conclusions, one can count these [processes], and, for instance, in proving certain theorems of elementary geometry (the Pythagoras theorem, [theorems] on remarkable points of triangles), one can very well decide which of the proofs is the simplest. [Author's note: Part of the last sentence is not only barely legible in Hilbert's notebook but also grammatically incorrect. Corrections and insertions that Hilbert made in this entry show that he wrote down the problem in haste.]