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Langton's Loops
Langton's loops are a particular "species" of artificial life in a cellular automaton created in 1984 by Christopher Langton. They consist of a loop of cells containing genetic information, which flows continuously around the loop and out along an "arm" (or pseudopod), which will become the daughter loop. The "genes" instruct it to make three left turns, completing the loop, which then disconnects from its parent. History In 1952 John von Neumann created the first cellular automaton (CA) with the goal of creating a self-replicating machine. This automaton was necessarily very complex due to its computation- and construction-universality. In 1968 Edgar F. Codd reduced the number of states from 29 in von Neumann's CA to 8 in his. When Christopher Langton did away with the universality condition, he was able to significantly reduce the automaton's complexity. Its self-replicating loops are based on one of the simplest elements in Codd's automaton, the periodic emitter. Specific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langtons Loop
Langtons House and Langtons Gardens are a grade II listed 18th century house and landscaped gardens located in Hornchurch, in the London Borough of Havering, Greater London. The house and gardens became local authority property in 1929 and are currently used as the borough register office and a public park. Langtons House was used as the council offices of Hornchurch Urban District Council from 1929 to 1965. History The house, built on the foundations of an older house in the early 18th century, stands in a picturesque landscaped garden with a lake, orangery, Public bathing, bath house and a gazebo, all dating from the end of the 18th century, when Hornchurch was a rural settlement. In 1776 Langtons and considerable property in Essex was owned by John Mayor (brewer), John Mayor a brewer who became MP for Abingdon and established HM Stationery Office. The house was purchased in 1797 by John Massu, whose family, originally Huguenot refugees, had become wealthy silk merchants in th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen infecting tobacco plants and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898,Dimmock p. 4 more than 9,000 virus species have been described in detail of the millions of types of viruses in the environment. Viruses are found in almost every ecosystem on Earth and are the most numerous type of biological entity. The study of viruses is known as virology, a subspeciality of microbiology. When infected, a host cell is often forced to rapidly produce thousands of copies of the original virus. When not inside an infected cell or in the process of infecting a cell, viruses exist in the form of independent particles, or ''virions'', consisting of (i) the genetic material, i.e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charles Darwin popularised the term "natural selection", contrasting it with selective breeding, artificial selection, which in his view is intentional, whereas natural selection is not. Genetic diversity, Variation exists within all populations of organisms. This occurs partly because random mutations arise in the genome of an individual organism, and their offspring can inherit such mutations. Throughout the lives of the individuals, their genomes interact with their environments to cause variations in traits. The environment of a genome includes the molecular biology in the Cell (biology), cell, other cells, other individuals, populations, species, as well as the abiotic environment. Because individuals with certain variants of the trait tend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SDSR Loop
SDSR is a four-letter abbreviation which may refer to: * Southern Downs Steam Railway Downs Explorer (originally known as Southern Downs Steam Railway) was founded in 1996, initially to restore the former Queensland Railways locomotive depot in Warwick.Strategic Defence and Security Review (other), three of the defence strategy policy reviews of the United Kingdom {{dab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perrier Loop
Perrier ( , also , ) is a French brand of natural bottled mineral water obtained at its source in Vergèze, located in the Gard '' département''. Perrier is known for its carbonation and its distinctive green bottle. Perrier was part of the Perrier Vittel Group SA, which became Nestlé Waters France after the acquisition of the company by Nestlé in 1992. Nestlé Waters France also includes Vittel, S.Pellegrino and Contrex. About The spring from which Perrier water is sourced is naturally carbonated, but the water and natural carbon dioxide gas are obtained independently. The water is then purified, and during bottling, the carbon dioxide gas is re-added so that the level of carbonation in bottled Perrier matches that of the Vergèze spring. In 1990, Perrier removed the "naturally sparkling" claim from its bottles under pressure from the United States Food and Drug Administration. Since at least 2019, Perrier water is no longer "reinforced with gas from the source" ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computable Function
Computable functions are the basic objects of study in computability theory. Computable functions are the formalized analogue of the intuitive notion of algorithms, in the sense that a function is computable if there exists an algorithm that can do the job of the function, i.e. given an input of the function domain it can return the corresponding output. Computable functions are used to discuss computability without referring to any concrete model of computation such as Turing machines or register machines. Any definition, however, must make reference to some specific model of computation but all valid definitions yield the same class of functions. Particular models of computability that give rise to the set of computable functions are the Turing-computable functions and the general recursive functions. Before the precise definition of computable function, mathematicians often used the informal term ''effectively calculable''. This term has since come to be identified with the com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moore Neighborhood
In cellular automata, the Moore neighborhood is defined on a two-dimensional square lattice and is composed of a central cell and the eight cells that surround it. Name The neighborhood is named after Edward F. Moore, a pioneer of cellular automata theory. Importance It is one of the two most commonly used neighborhood types, the other one being the von Neumann neighborhood, which excludes the corner cells. The well known Conway's Game of Life, for example, uses the Moore neighborhood. It is similar to the notion of 8-connected pixels in computer graphics. The Moore neighbourhood of a cell is the cell itself and the cells at a Chebyshev distance of 1. The concept can be extended to higher dimensions, for example forming a 26-cell cubic neighborhood for a cellular automaton in three dimensions, as used by 3D Life. In dimension ''d,'' where 0 \le d, d \in \mathbb, the size of the neighborhood is 3''d'' − 1. In two dimensions, the number of cells in an ''ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Byl's Loop
The Byl's loop is an artificial lifeform similar in concept to Langton's loop. It is a two-dimensional, 5-neighbor cellular automaton with 6 states per cell, and was developed in 1989 by John Byl, from the Department of Mathematical Sciences of Trinity Western University. Details The Byl's loop was developed just a few years after Langton's simplification of Codd's automaton, which produced a simpler automaton that would reproduce itself in 151 time-steps. John Byl simplified Langton's automaton further, with an even smaller automaton that reproduced in just 25 time-steps. Byl's automaton consisted of an array of 12 chips — of which 4 or 5 could be counted as the instruction tape — and 43 transition rules, while Langton's device consisted of some 10×15 chips, including an instruction tape of 33 chips, plus some 190 transition rules. Essentially, the simplification consisted in using fewer cellular states (6 as compared with Langton's 8) and a smaller replicating loop (1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
