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πŸ”— Three-Domain System

πŸ”— Biology πŸ”— Evolutionary biology πŸ”— Tree of Life

The three-domain system is a biological classification introduced by Carl Woese et al. in 1990 that divides cellular life forms into archaea, bacteria, and eukaryote domains. In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria (now Bacteria) and Archaebacteria (now Archaea). Woese argued that, on the basis of differences in 16S rRNA genes, these two groups and the eukaryotes each arose separately from an ancestor with poorly developed genetic machinery, often called a progenote. To reflect these primary lines of descent, he treated each as a domain, divided into several different kingdoms. Woese initially used the term "kingdom" to refer to the three primary phylogenic groupings, and this nomenclature was widely used until the term "domain" was adopted in 1990.

Parts of the three-domain theory have been fiercly challenged by scientists such as Radhey S. Gupta, who argues that the primary division within prokaryotes should be between those surrounded by a single membrane, and those with two membranes.

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πŸ”— Hyperparasite

πŸ”— Biology πŸ”— Insects πŸ”— Ecology

A hyperparasite, also known as a metaparasite is a parasite whose host, often an insect, is also a parasite, often specifically a parasitoid. Hyperparasites are found mainly among the wasp-waisted Apocrita within the Hymenoptera, and in two other insect orders, the Diptera (true flies) and Coleoptera (beetles). Seventeen families in Hymenoptera and a few species of Diptera and Coleoptera are hyperparasitic. Hyperparasitism developed from primary parasitism, which evolved in the Jurassic period in the Hymenoptera. Hyperparasitism intrigues entomologists because of its multidisciplinary relationship to evolution, ecology, behavior, biological control, taxonomy, and mathematical models.

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πŸ”— Closed-eye hallucination

πŸ”— Medicine πŸ”— Biology

Closed-eye hallucinations and closed-eye visualizations (CEV) are a distinct class of hallucination. These types of hallucinations generally only occur when one's eyes are closed or when one is in a darkened room. They can be a form of phosphene. Some people report closed-eye hallucinations under the influence of psychedelics. These are reportedly of a different nature than the "open-eye" hallucinations of the same compounds. Similar hallucinations that occur due to loss of vision are called visual release hallucinations.

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πŸ”— Invented Tradition

πŸ”— History πŸ”— Biology πŸ”— Politics πŸ”— Anthropology πŸ”— Sociology πŸ”— Conservatism πŸ”— Folklore

Invented traditions are cultural practices that are presented or perceived as traditional, arising from the people starting in the distant past, but which in fact are relatively recent and often even consciously invented by identifiable historical actors. The concept was highlighted in the 1983 book The Invention of Tradition, edited by Eric Hobsbawm and Terence Ranger. Hobsbawm's introduction argues that many "traditions" which "appear or claim to be old are often quite recent in origin and sometimes invented." This "invention" is distinguished from "starting" or "initiating" a tradition that does not then claim to be old. The phenomenon is particularly clear in the modern development of the nation and of nationalism, creating a national identity promoting national unity, and legitimising certain institutions or cultural practices.

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πŸ”— 1984 Rajneeshee bioterror attack

πŸ”— United States πŸ”— Medicine πŸ”— Oregon πŸ”— Crime πŸ”— Religion πŸ”— Biology πŸ”— Terrorism

The 1984 Rajneeshee bioterror attack was the food poisoning of 751Β individuals in The Dalles, Oregon, through the deliberate contamination of salad bars at ten local restaurants with Salmonella. A group of prominent followers of Bhagwan Shree Rajneesh (later known as Osho) led by Ma Anand Sheela had hoped to incapacitate the voting population of the city so that their own candidates would win the 1984 Wasco County elections. The incident was the first and is the single largest bioterrorist attack in United States history.

Having previously gained political control of Antelope, Oregon, Rajneesh's followers, who were based in nearby Rajneeshpuram, sought election to two of the three seats on the Wasco County Circuit Court that were up for election in November 1984. Fearing they would not gain enough votes, some Rajneeshpuram officials decided to incapacitate voters in The Dalles, the largest population center in Wasco County. The chosen biological agent was Salmonella enterica Typhimurium, which was first delivered through glasses of water to two County Commissioners and then, on a larger scale, at salad bars and in salad dressing.

As a result of the attack, 751 people contracted salmonellosis, 45Β of whom were hospitalized, but none died. Although an initial investigation by the Oregon Public Health Division and the Centers for Disease Control did not rule out deliberate contamination, the agents and contamination were only confirmed a year later. On February 28, 1985, Congressman James H. Weaver gave a speech in the United States House of Representatives in which he "accused the Rajneeshees of sprinkling Salmonella culture on salad bar ingredients in eight restaurants".

At a press conference in September 1985, Rajneesh accused several of his followers of participation in this and other crimes, including an aborted plan in 1985 to assassinate a United States Attorney, and he asked state and federal authorities to investigate. Oregon Attorney General David B. Frohnmayer set up an interagency task force, composed of Oregon State Police and the Federal Bureau of Investigation, and executed search warrants in Rajneeshpuram. A sample of bacteria matching the contaminant that had sickened the town residents was found in a Rajneeshpuram medical laboratory. Two leading Rajneeshpuram officials were convicted on charges of attempted murder and served 29Β months of 20-year sentences in a minimum-security federal prison.

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πŸ”— DNA origami

πŸ”— Biology πŸ”— Molecular and Cell Biology πŸ”— Genetics

DNA origami is the nanoscale folding of DNA to create non-arbitrary two- and three-dimensional shapes at the nanoscale. The specificity of the interactions between complementary base pairs make DNA a useful construction material, through design of its base sequences. DNA is a well-understood material that is suitable for creating scaffolds that hold other molecules in place or to create structures all on its own.

DNA origami was the cover story of Nature on March 16, 2006. Since then, DNA origami has progressed past an art form and has found a number of applications from drug delivery systems to uses as circuitry in plasmonic devices; however, most applications remain in a concept or testing phase.

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πŸ”— Artificial Photosynthesis

πŸ”— Environment πŸ”— Biology πŸ”— Physics πŸ”— Guild of Copy Editors πŸ”— Energy πŸ”— Chemical and Bio Engineering

Artificial photosynthesis is a chemical process that biomimics the natural process of photosynthesis to convert sunlight, water, and carbon dioxide into carbohydrates and oxygen. The term artificial photosynthesis is commonly used to refer to any scheme for capturing and storing the energy from sunlight in the chemical bonds of a fuel (a solar fuel). Photocatalytic water splitting converts water into hydrogen and oxygen and is a major research topic of artificial photosynthesis. Light-driven carbon dioxide reduction is another process studied that replicates natural carbon fixation.

Research of this topic includes the design and assembly of devices for the direct production of solar fuels, photoelectrochemistry and its application in fuel cells, and the engineering of enzymes and photoautotrophic microorganisms for microbial biofuel and biohydrogen production from sunlight.

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πŸ”— Indefinite lifespan

πŸ”— Medicine πŸ”— Biology πŸ”— Skepticism πŸ”— Transhumanism πŸ”— Alternative Views πŸ”— Guild of Copy Editors πŸ”— Alternative medicine πŸ”— Longevity

Life extension is the idea of extending the human lifespan, either modestly – through improvements in medicine – or dramatically by increasing the maximum lifespan beyond its generally settled limit of 125 years. The ability to achieve such dramatic changes, however, does not currently exist.

Some researchers in this area, and "life extensionists", "immortalists" or "longevists" (those who wish to achieve longer lives themselves), believe that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans (agerasia) through complete rejuvenation to a healthy youthful condition. The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.

The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry that promotes the use of hormones as a treatment for consumers to slow or reverse the aging process in the US market generated about $50Β billion of revenue a year in 2009. The use of such products has not been proven to be effective or safe.

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πŸ”— Tendril perversion – spontaneous symmetry breaking, uncoiling helical structures

πŸ”— Mathematics πŸ”— Biology πŸ”— Physics πŸ”— Plants

Tendril perversion, often referred to in context as simply perversion, is a geometric phenomenon found in helical structures such as plant tendrils, in which a helical structure forms that is divided into two sections of opposite chirality, with a transition between the two in the middle. A similar phenomenon can often be observed in kinked helical cables such as telephone handset cords.

The phenomenon was known to Charles Darwin, who wrote in 1865,

A tendril ... invariably becomes twisted in one part in one direction, and in another part in the opposite direction... This curious and symmetrical structure has been noticed by several botanists, but has not been sufficiently explained.

The term "tendril perversion" was coined by Goriely and Tabor in 1998 based on the word perversion found in the 19th Century science literature. "Perversion" is a transition from one chirality to another and was known to James Clerk Maxwell, who attributed it to the topologist J. B. Listing.

Tendril perversion can be viewed as an example of spontaneous symmetry breaking, in which the strained structure of the tendril adopts a configuration of minimum energy while preserving zero overall twist.

Tendril perversion has been studied both experimentally and theoretically. Gerbode et al. have made experimental studies of the coiling of cucumber tendrils. A detailed study of a simple model of the physics of tendril perversion was made by MacMillen and Goriely in the early 2000s. Liu et al. showed in 2014 that "the transition from a helical to a hemihelical shape, as well as the number of perversions, depends on the height to width ratio of the strip's cross-section."

Generalized tendril perversions were put forward by Silva et al., to include perversions that can be intrinsically produced in elastic filaments, leading to a multiplicity of geometries and dynamical properties.

πŸ”— DNA Computing

πŸ”— Computing πŸ”— Computer science πŸ”— Biology πŸ”— Chemistry πŸ”— Genetics

DNA computing is a branch of computing which uses DNA, biochemistry, and molecular biology hardware, instead of the traditional silicon-based computer technologies. Research and development in this area concerns theory, experiments, and applications of DNA computing. The term "molectronics" has sometimes been used, but this term has already been used for an earlier technology, a then-unsuccessful rival of the first integrated circuits; this term has also been used more generally, for molecular-scale electronic technology.

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