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πŸ”— Chester Carlson – Inventor of Xerography

πŸ”— United States πŸ”— Biography πŸ”— Physics πŸ”— Biography/science and academia πŸ”— Physics/Biographies πŸ”— United States/Washington - Seattle πŸ”— Buddhism πŸ”— Invention

Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington.

He is best known for inventing electrophotography, the process performed today by millions of photocopiers worldwide. Carlson's process produced a dry copy, as contrasted with the wet copies then produced by the mimeograph process. Carlson's process was renamed xerography, a term that means "dry writing."

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πŸ”— Gridcoin: An open source cryptocurrency that rewards work performed on the BOINC

πŸ”— Computing πŸ”— Computing/Software πŸ”— Numismatics πŸ”— Numismatics/Cryptocurrency πŸ”— Cryptocurrency

Gridcoin (ticker: GRC) is an open source cryptocurrency which securely rewards volunteer computing performed on the BOINC, a distributed computing platform that is home to over 30 science projects spanning a range of scientific disciplines.

Gridcoin attempts to address and ease the environmental energy impact of cryptocurrency mining through its proof-of-research and proof-of-stake protocols, as compared to the proof of work system used by Bitcoin.

πŸ”— Whirlwind I

πŸ”— Computing πŸ”— Military history πŸ”— Military history/North American military history πŸ”— Military history/United States military history πŸ”— Military history/Military science, technology, and theory πŸ”— Military history/Cold War πŸ”— Computing/Early computers

Whirlwind I was a Cold War-era vacuum tube computer developed by the MIT Servomechanisms Laboratory for the U.S. Navy. Operational in 1951, it was among the first digital electronic computers that operated in real-time for output, and the first that was not simply an electronic replacement of older mechanical systems.

It was one of the first computers to calculate in bit-parallel (rather than bit-serial), and was the first to use magnetic-core memory.

Its development led directly to the Whirlwind II design used as the basis for the United States Air Force SAGE air defense system, and indirectly to almost all business computers and minicomputers in the 1960s, particularly because of the mantra "short word length, speed, people."

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πŸ”— Sator Square

πŸ”— Religion πŸ”— Classical Greece and Rome πŸ”— Middle Ages πŸ”— Middle Ages/History πŸ”— Cryptography πŸ”— Cryptography/Computer science πŸ”— Latin πŸ”— Christianity πŸ”— Jewish history πŸ”— Occult πŸ”— Mysticism

The Sator Square (or Rotas Square) is a word square containing a five-word Latin palindrome. The earliest form has ROTAS as the top line, but in time the version with SATOR on the top line became dominant. It is a 5X5 square made up of five 5-letter words, thus consisting of 25 letters in total. These 25 letters are all derived from 8 Latin letters: 5 consonants (S, T, R, P, N) and 3 vowels (A, E, O).


In particular, this is a square 2D palindrome, which is when a square text admits four symmetries: identity, two diagonal reflections, and 180 degree rotation. As can be seen, the text may be read top-to-bottom, bottom-to-top, left-to-right, or right-to-left; and it may be rotated 180 degrees and still be read in all those ways.

The Sator Square is the earliest dateable 2D palindrome. It was found in the ruins of Pompeii, at Herculaneum, a city buried in the ash of Mount Vesuvius in 79 AD. It consists of a sentence written in Latin: "Sator Arepo Tenet Opera Rotas." Its translation has been the subject of speculation with no clear consensus; see below for details.

Other 2D Palindrome examples may be found carved on stone tablets or pressed into clay before being fired.

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πŸ”— PainStation

πŸ”— Video games

Painstation is an art object and arcade game based on Pong developed by the artists' group "/////////fur//// art entertainment interfaces", with pain feedback.

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πŸ”— Tell HN: There will be a Blue moon in December

πŸ”— Time πŸ”— Moon

A blue moon is an additional full moon that appears in a subdivision of a year: either the third of four full moons in a season, or a second full moon in a month of the common calendar.

The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon appearing with a bluish tinge) may occur under certain atmospheric conditions – for instance, if volcanic eruptions or fires release particles in the atmosphere of just the right size to preferentially scatter red light.

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πŸ”— Confocal microscopy

πŸ”— Technology πŸ”— Physics πŸ”— Neuroscience πŸ”— Molecular Biology πŸ”— Molecular Biology/Molecular and Cell Biology

Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures (a process known as optical sectioning) within an object. This technique is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection and materials science.

Light travels through the sample under a conventional microscope as far into the specimen as it can penetrate, while a confocal microscope only focuses a smaller beam of light at one narrow depth level at a time. The CLSM achieves a controlled and highly limited depth of field.

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πŸ”— Intermarium

πŸ”— International relations πŸ”— History πŸ”— Europe πŸ”— Politics πŸ”— Poland πŸ”— Lithuania πŸ”— Eastern Europe

Intermarium (Polish: MiΔ™dzymorze, Polish pronunciation:Β [mΚ²Ι›ndΝ‘zɨˈmɔʐɛ]) was a geopolitical project conceived by politicians in successor states of the former Polish–Lithuanian Commonwealth in several iterations, some of which anticipated the inclusion as well of other, neighboring states. The proposed multinational polity would have extended across territories lying between the Baltic, Black and Adriatic Seas, hence the name meaning "Between-Seas".

Prospectively a federation of Central and Eastern European countries, the post-World War I Intermarium plan pursued by Polish leader and former political prisoner of the Russian Empire, JΓ³zef PiΕ‚sudski (1867–1935), sought to recruit to the proposed federation the Baltic states (Lithuania, Latvia, Estonia), Finland, Belarus, Ukraine, Hungary, Romania, Yugoslavia and Czechoslovakia. The Polish name MiΔ™dzymorze (from miΔ™dzy, "between"; and morze, "sea"), meaning "Between-Seas", was rendered into Latin as "Intermarium."

The proposed federation was meant to emulate the Polish–Lithuanian Commonwealth, stretching from the Baltic Sea to the Black Sea, that, from the end of the 16th century to the end of the 18th, had united the Kingdom of Poland and the Grand Duchy of Lithuania. Intermarium complemented PiΕ‚sudski's other geopolitical vision, Prometheism, whose goal was the dismemberment of the Russian Empire and that Empire's divestment of its territorial acquisitions.

Intermarium was, however, perceived by some Lithuanians as a threat to their newly established independence, and by some Ukrainians as a threat to their aspirations for independence, and while France backed the proposal, it was opposed by Russia and by most other Western powers. Within two decades of the failure of PiΕ‚sudski's grand scheme, all the countries that he had viewed as candidates for membership in the Intermarium federation had fallen to the Soviet Union or Nazi Germany, except for Finland (which suffered some territorial losses in the 1939–40 Winter War with the Soviet Union).

πŸ”— Looped Square Or ⌘

πŸ”— Apple Inc./Macintosh πŸ”— Apple Inc. πŸ”— Apple Inc./Mac

The Command key (sometimes abbreviated as Cmd key), ⌘, formerly also known as the Apple key or open Apple key, is a modifier key present on Apple keyboards. The Command key's purpose is to allow the user to enter keyboard commands in applications and in the system. An "extended" Macintosh keyboardβ€”the most common typeβ€”has two command keys, one on each side of the space bar; some compact keyboards have one only on the left.

The ⌘ symbol (the "looped square") was chosen by Susan Kare after Steve Jobs decided that the use of the Apple logo in the menu system (where the keyboard shortcuts are displayed) would be an over-use of the logo. Apple's adaptation of the symbolβ€”encoded in Unicode at U+2318β€”was derived in part from its use in Nordic countries as an indicator of cultural locations and places of interest. The symbol is known by various other names, including "Saint John's Arms" and "Bowen knot".

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πŸ”— Shepard Tone

πŸ”— Professional sound production

A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the bass pitch of the tone moving upward or downward, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower.

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