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π Hapax legomenon
In corpus linguistics, a hapax legomenon ( also or ; pl. hapax legomena; sometimes abbreviated to hapax) is a word that occurs only once within a context, either in the written record of an entire language, in the works of an author, or in a single text. The term is sometimes incorrectly used to describe a word that occurs in just one of an author's works, but more than once in that particular work. Hapax legomenon is a transliteration of Greek αΌ ΟΞ±ΞΎ λΡγΟμΡνον, meaning "(something) being said (only) once".
The related terms dis legomenon, tris legomenon, and tetrakis legomenon respectively (, , ) refer to double, triple, or quadruple occurrences, but are far less commonly used.
Hapax legomena are quite common, as predicted by Zipf's law, which states that the frequency of any word in a corpus is inversely proportional to its rank in the frequency table. For large corpora, about 40% to 60% of the words are hapax legomena, and another 10% to 15% are dis legomena. Thus, in the Brown Corpus of American English, about half of the 50,000 distinct words are hapax legomena within that corpus.
Hapax legomenon refers to a word's appearance in a body of text, not to either its origin or its prevalence in speech. It thus differs from a nonce word, which may never be recorded, may find currency and may be widely recorded, or may appear several times in the work which coins it, and so on.
Discussed on
- "Hapax legomenon" | 2014-03-06 | 87 Upvotes 40 Comments
π Alto Trek, a networked multiplayer game from 1978
Alto Trek is a computer game, developed by Gene Ball and Rick Rashid for the Xerox Alto while they were graduate students at the University of Rochester during the late 1970s. It is one of the first networked multiplayer games.
Discussed on
- "Alto Trek, a networked multiplayer game from 1978" | 2023-07-14 | 110 Upvotes 25 Comments
π Galton Board
The bean machine, also known as the Galton Board or quincunx, is a device invented by Sir Francis Galton to demonstrate the central limit theorem, in particular that with sufficient sample size the binomial distribution approximates a normal distribution. Among its applications, it afforded insight into regression to the mean or "regression to mediocrity".
Discussed on
- "Galton Board" | 2019-06-18 | 98 Upvotes 30 Comments
π Pink Noise
Pink noise or β1βf noise is a signal or process with a frequency spectrum such that the power spectral density (energy or power per frequency interval) is inversely proportional to the frequency of the signal. In pink noise, each octave (halving or doubling in frequency) carries an equal amount of noise energy.
Pink noise is one of the most common signals in biological systems.
The name arises from the pink appearance of visible light with this power spectrum. This is in contrast with white noise which has equal intensity per frequency interval.
Discussed on
- "Pink Noise" | 2019-09-27 | 10 Upvotes 4 Comments
π Naismith's Rule
Naismith's rule helps with the planning of a walking or hiking expedition by calculating how long it will take to travel the intended route, including any extra time taken when walking uphill. This rule of thumb was devised by William W. Naismith, a Scottish mountaineer, in 1892. A modern version can be formulated as follows:
- Allow one hour for every 3 miles (5Β km) forward, plus an additional hour for every 2,000 feet (600Β m) of ascent.
Discussed on
- "Naismith's Rule" | 2024-04-11 | 47 Upvotes 14 Comments
π Surveillance Capitalism
Surveillance capitalism has a number of meanings around the commodification of personal information. Since 2014, social psychologist Shoshana Zuboff has used and popularized the term.
Discussed on
- "Surveillance Capitalism" | 2021-07-27 | 16 Upvotes 1 Comments
- "Surveillance Capitalism" | 2020-04-12 | 71 Upvotes 38 Comments
- "Surveillance Capitalism" | 2019-03-13 | 14 Upvotes 2 Comments
π Lockheed CL-1201 nuclear-powered transport aircraft concept
The Lockheed CL-1201 was a design study by Lockheed for a giant 6,000 ton nuclear-powered transport aircraft in the late 1960s. One envisioned use of the concept was as an airborne aircraft carrier.
Discussed on
- "Lockheed CL-1201 nuclear-powered transport aircraft concept" | 2024-08-25 | 23 Upvotes 2 Comments
π Fibonacci Coding
In mathematics and computing, Fibonacci coding is a universal code which encodes positive integers into binary code words. It is one example of representations of integers based on Fibonacci numbers. Each code word ends with "11" and contains no other instances of "11" before the end.
The Fibonacci code is closely related to the Zeckendorf representation, a positional numeral system that uses Zeckendorf's theorem and has the property that no number has a representation with consecutive 1s. The Fibonacci code word for a particular integer is exactly the integer's Zeckendorf representation with the order of its digits reversed and an additional "1" appended to the end.
Discussed on
- "Fibonacci Coding" | 2021-07-04 | 61 Upvotes 27 Comments
π Diatoms make 20% of Earth's oxygen and can double in population every 24 hours
Diatoms (diΓ‘-tom-os 'cut in half', from diΓ‘, 'through' or 'apart'; and the root of tΓ©m-n-Ε, 'I cut'.) are a major group of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion metric tons of silicon each year from the waters in which they live, and contribute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half-mile (800m) deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the BodΓ©lΓ© Depression, which was once made up a system of fresh-water lakes.
Diatoms are unicellular: they occur either as solitary cells or in colonies, which can take the shape of ribbons, fans, zigzags, or stars. Individual cells range in size from 2 to 200 micrometers. In the presence of adequate nutrients and sunlight, an assemblage of living diatoms doubles approximately every 24 hours by asexual multiple fission; the maximum life span of individual cells is about six days. Diatoms have two distinct shapes: a few (centric diatoms) are radially symmetric, while most (pennate diatoms) are broadly bilaterally symmetric. A unique feature of diatom anatomy is that they are surrounded by a cell wall made of silica (hydrated silicon dioxide), called a frustule. These frustules have structural coloration due to their photonic nanostructure, prompting them to be described as "jewels of the sea" and "living opals". Movement in diatoms primarily occurs passively as a result of both water currents and wind-induced water turbulence; however, male gametes of centric diatoms have flagella, permitting active movement for seeking female gametes. Similar to plants, diatoms convert light energy to chemical energy by photosynthesis, although this shared autotrophy evolved independently in both lineages. Unusually for autotrophic organisms, diatoms possess a urea cycle, a feature that they share with animals, although this cycle is used to different metabolic ends in diatoms. The family Rhopalodiaceae also possess a cyanobacterial endosymbiont called a spheroid body. This endosymbiont has lost its photosynthetic properties, but has kept its ability to perform nitrogen fixation, allowing the diatom to fix atmospheric nitrogen.
The study of diatoms is a branch of phycology. Diatoms are classified as eukaryotes, organisms with a membrane-bound cell nucleus, that separates them from the prokaryotes archaea and bacteria. Diatoms are a type of plankton called phytoplankton, the most common of the plankton types. Diatoms also grow attached to benthic substrates, floating debris, and on macrophytes. They comprise an integral component of the periphyton community. Another classification divides plankton into eight types based on size: in this scheme, diatoms are classed as microalgae. Several systems for classifying the individual diatom species exist. Fossil evidence suggests that diatoms originated during or before the early Jurassic period, which was about 150 to 200 million years ago.
Diatoms are used to monitor past and present environmental conditions, and are commonly used in studies of water quality. Diatomaceous earth (diatomite) is a collection of diatom shells found in the earth's crust. They are soft, silica-containing sedimentary rocks which are easily crumbled into a fine powder and typically have a particle size of 10 to 200 ΞΌm. Diatomaceous earth is used for a variety of purposes including for water filtration, as a mild abrasive, in cat litter, and as a dynamite stabilizer.
Discussed on
- "Diatoms make 20% of Earth's oxygen and can double in population every 24 hours" | 2019-07-07 | 11 Upvotes 2 Comments
π The Overview Effect
The overview effect is a cognitive shift in awareness reported by some astronauts during spaceflight, often while viewing the Earth from outer space.
It is the experience of seeing firsthand the reality of the Earth in space, which is immediately understood to be a tiny, fragile ball of life, "hanging in the void", shielded and nourished by a paper-thin atmosphere. From space, national boundaries vanish, the conflicts that divide people become less important, and the need to create a planetary society with the united will to protect this "pale blue dot" becomes both obvious and imperative.
The thing that really surprised me was that it [Earth] projected an air of fragility. And why, I donβt know. I donβt know to this day. I had a feeling itβs tiny, itβs shiny, itβs beautiful, itβs home, and itβs fragile.
Astronauts Michael Collins, Ron Garan, Rusty Schweikart, Edgar Mitchell, Tom Jones, Scott Kelly, James Irwin, Mike Massimino, AndrΓ© Kuipers, Chris Hadfield, and Sally Ride are all reported to have experienced the effect.
The term and concept were coined in 1987 by Frank White, who explored the theme in his book The Overview EffectΒ β Space Exploration and Human Evolution (Houghton-Mifflin, 1987), (AIAA, 1998).
In 2018, the SpaceBuzz project was created so "children around the world can also get to experience the Overview Effect." It was announced in a press release on December 20 by astronaut AndrΓ© Kuipers on the European Space Agency's (ESA) website. Spacebuzz aims to give children an overview effect like experience using virtual reality (VR) in order to have the same insight astronauts have when seeing planet Earth from space. Spacebuzz is a project started by the Overview Effect Foundation backed by ESA and the Netherlands Space Office..
In late 2019 it was reported that researchers at the University of Missouri aimed to reproduce the experience, with an isolation tank, half a tonne of Epsom salts, and a waterproof VR headset.
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- "The Overview Effect" | 2021-08-15 | 44 Upvotes 27 Comments
- "The Overview Effect" | 2019-08-21 | 47 Upvotes 6 Comments