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🔗 Companies 🔗 Aviation 🔗 Spaceflight 🔗 Aviation/aircraft 🔗 Rocketry

Rotary Rocket Company was a rocketry company that developed the Roton concept in the late 1990s as a fully reusable single-stage-to-orbit (SSTO) crewed spacecraft. The design was initially conceived by Bevin McKinney, who shared it with Gary Hudson. In 1996, Rotary Rocket Company was formed to commercialize the concept. The Roton was intended to reduce costs of launching payloads into low earth orbit by a factor of ten.

The company gathered considerable venture capital from angel investors and opened a factory headquartered in a 45,000-square-foot (4,200 m²) facility at Mojave Air and Space Port in Mojave, California. The fuselage for their vehicles was made by Scaled Composites, at the same airport, while the company developed the novel engine design and helicopter-like landing system. A full-scale test vehicle made three hover flights in 1999, but the company exhausted its funds and closed its doors in early 2001.

🔗 Physics 🔗 Firearms

A projectile is any object thrown into space (empty or not) by the exertion of a force. Although any object in motion through space (for example a thrown baseball) may be called a projectile, the term more commonly refers to a ranged weapon. Mathematical equations of motion are used to analyze projectile trajectory. An object projected at an angle to the horizontal has both the vertical and horizontal components of velocity. The vertical component of the velocity on the y-axis given as Vy=USin(teta) while the horizontal component of the velocity Vx=UCos(teta). There are various terms used in projectiles at specific angle teta 1. Time to reach maximum height. It is symbolized as (t), which is the time taken for the projectile to reach the maximum height from the plane of projection. Mathematically, it is given as t=USin(teta)/g Where g=acceleration due to gravity(app 9.81m/s²) U= initial velocity (m/s) teta= angle made by the projectile with the horizontal axis.

2. Time of flight (T): this is the total time taken for the projectile to fall back to the same plane from which it was projected. Mathematically it is given as T=2USin(teta)/g

3. Maximum Height (H): this is the maximum height attained by the projectile OR the maximum displacement on the vertical axis(y-axis) covered by the projectile. It is given as H= U²Sin²(teta)/2g

4. Range(R): The Range of a projectile is the horizontal distance covered (on the x-axis) by the projectile. Mathematically, R= U²Sin2(teta)/g. The Range is maximum when angle teta= 45° I.e Sin2(teta)=1.

🔗 Spaceflight 🔗 Rocketry

Black Arrow, officially capitalised BLACK ARROW, was a British satellite carrier rocket. Developed during the 1960s, it was used for four launches between 1969 and 1971. Its final flight was the first and only successful orbital launch to be conducted by the United Kingdom, and placed the Prospero satellite into low Earth orbit.

Black Arrow originated from studies by the Royal Aircraft Establishment for carrier rockets based on the Black Knight rocket, with the project being authorised in 1964. It was initially developed by Saunders-Roe, and later Westland Aircraft as the result of a merger.

Black Arrow was a three-stage rocket, fuelled by RP-1 paraffin (kerosene) and high test peroxide, a concentrated form of hydrogen peroxide (85% hydrogen peroxide + 15% water). It was retired after only four launches in favour of using American Scout rockets, which the Ministry of Defence calculated to be cheaper than maintaining the Black Arrow programme.

🔗 Olympics 🔗 Classical Greece and Rome 🔗 Greece 🔗 Martial arts 🔗 Mixed martial arts

Pankration (; Greek: παγκράτιον) was a sporting event introduced into the Greek Olympic Games in 648 BC and was an empty-hand submission sport with scarcely any rules. The athletes used boxing and wrestling techniques, but also others, such as kicking and holds, locks and chokes on the ground. The term comes from the Greek παγκράτιον [paŋkrátion], literally meaning "all of power" from πᾶν (pan) "all" and κράτος (kratos) "strength, might, power".

It was known in ancient times for its ferocity and allowance of such tactics as knees to the head and eye gouging. One ancient account tells of a situation in which the judges were trying to determine the winner of a match. The difficulty lay in that fact that both men had died in the arena from their injuries, making it hard to determine a victor. Eventually, the judges decided the winner was the one who didn't have his eyes gouged out. Over time, however, maneuvers like eye gouging were discouraged to prevent such unpleasant incidents.

🔗 Biology 🔗 Genetics 🔗 Computational Biology 🔗 Evolutionary biology 🔗 Human Genetic History

The last universal common ancestor (LUCA), also called the last universal ancestor (LUA), or concestor, is the most recent population of organisms from which all organisms now living on Earth have a common descent, the most recent common ancestor of all current life on Earth. (A related concept is that of progenote.) LUCA is not thought to be the first life on Earth but only one of many early organisms, all the others becoming extinct.

While there is no specific fossil evidence of LUCA, it can be studied by comparing the genomes of all modern organisms, its descendants. By this means, a 2016 study identified a set of 355 genes most likely to have been present in LUCA. (However, some of those genes could have developed later, then spread universally by horizontal gene transfer between archaea and bacteria.) The genes describe a complex life form with many co-adapted features, including transcription and translation mechanisms to convert information from DNA to RNA to proteins. The study concluded that the LUCA probably lived in the high-temperature water of deep sea vents near ocean-floor magma flows.

Studies from 2000 to 2018 have suggested an increasingly ancient time for LUCA. In 2000, estimations suggested LUCA existed 3.5 to 3.8 billion years ago in the Paleoarchean era, a few hundred million years after the earliest fossil evidence of life, for which there are several candidates ranging in age from 3.48 to 4.28 billion years ago. A 2018 study from the University of Bristol, applying a molecular clock model, places the LUCA shortly after 4.5 billion years ago, within the Hadean.

Charles Darwin first proposed the theory of universal common descent through an evolutionary process in his book On the Origin of Species in 1859: "Therefore I should infer from analogy that probably all the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." Later biologists have separated the problem of the origin of life from that of the LUCA.

🔗 Business 🔗 Psychology 🔗 Languages 🔗 Anthroponymy

Nominative determinism is the hypothesis that people tend to gravitate towards areas of work that fit their names. The term was first used in the magazine New Scientist in 1994, after the magazine's humorous Feedback column noted several studies carried out by researchers with remarkably fitting surnames. These included a book on polar explorations by Daniel Snowman and an article on urology by researchers named Splatt and Weedon. These and other examples led to light-hearted speculation that some sort of psychological effect was at work. Since the term appeared, nominative determinism has been an irregularly recurring topic in New Scientist, as readers continue to submit examples. Nominative determinism differs from the related concept aptronym, and its synonyms aptonym, namephreak, and Perfect Fit Last Name, in that it focuses on causality. "Aptronym" merely means the name is fitting, without saying anything about why it has come to fit.

The idea that people are drawn to professions that fit their name was suggested by psychologist Carl Jung, citing as an example Sigmund Freud who studied pleasure and whose surname means "joy". A few recent empirical studies have indicated that certain professions are disproportionately represented by people with appropriate surnames (and sometimes given names), though the methods of these studies have been challenged. One explanation for nominative determinism is implicit egotism, which states that humans have an unconscious preference for things they associate with themselves. An alternative explanation is genetic: a person might be named Smith or Taylor because that was originally their occupation, and they would pass on their genes to their descendants, including an aptitude for activities involving strength in the case of Smith, or dexterity in the case of Taylor.

🔗 Biology 🔗 Science Fiction 🔗 Chemistry

Hypothetical types of biochemistry are forms of biochemistry speculated to be scientifically viable but not proven to exist at this time. The kinds of living organisms currently known on Earth all use carbon compounds for basic structural and metabolic functions, water as a solvent, and DNA or RNA to define and control their form. If life exists on other planets or moons, it may be chemically similar; it is also possible that there are organisms with quite different chemistries—for instance, involving other classes of carbon compounds, compounds of another element, or another solvent in place of water.

The possibility of life-forms being based on "alternative" biochemistries is the topic of an ongoing scientific discussion, informed by what is known about extraterrestrial environments and about the chemical behaviour of various elements and compounds. It is of interest in synthetic biology and is also a common subject in science fiction.

The element silicon has been much discussed as a hypothetical alternative to carbon. Silicon is in the same group as carbon on the periodic table and, like carbon, it is tetravalent. Hypothetical alternatives to water include ammonia, which, like water, is a polar molecule, and cosmically abundant; and non-polar hydrocarbon solvents such as methane and ethane, which are known to exist in liquid form on the surface of Titan.

🔗 Molecular and Cell Biology 🔗 Microbiology 🔗 Genetics 🔗 Citizendium Porting 🔗 Evolutionary biology

Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the evolution of many organisms.

Horizontal gene transfer is the primary mechanism for the spread of antibiotic resistance in bacteria, and plays an important role in the evolution of bacteria that can degrade novel compounds such as human-created pesticides and in the evolution, maintenance, and transmission of virulence. It often involves temperate bacteriophages and plasmids. Genes responsible for antibiotic resistance in one species of bacteria can be transferred to another species of bacteria through various mechanisms of HGT such as transformation, transduction and conjugation, subsequently arming the antibiotic resistant genes' recipient against antibiotics. The rapid spread of antibiotic resistance genes in this manner is becoming medically challenging to deal with. Ecological factors may also play a role in the LGT of antibiotic resistant genes. It is also postulated that HGT promotes the maintenance of a universal life biochemistry and, subsequently, the universality of the genetic code.

Most thinking in genetics has focused upon vertical transfer, but the importance of horizontal gene transfer among single-cell organisms is beginning to be acknowledged.

Gene delivery can be seen as an artificial horizontal gene transfer, and is a form of genetic engineering.

🔗 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.

🔗 Psychology

The psychology of music preference refers to the psychological factors behind peoples' different music preferences. Music is heard by people daily in many parts of the world, and affects people in various ways from emotion regulation to cognitive development, along with providing a means for self-expression. Music training has been shown to help improve intellectual development and ability, though no connection has been found as to how it affects emotion regulation. Numerous studies have been conducted to show that individual personality can have an effect on music preference, mostly using personality, though a recent meta-analysis has shown that personality in itself explains little variance in music preferences. These studies are not limited to American culture, as they have been conducted with significant results in countries all over the world, including Japan, Germany, and Spain.