text stringlengths 1 2.7k | source stringlengths 21 174 |
|---|---|
H. G. Wells was inspired by the work of Rutherford to write about an "atom bomb" in a 1914 novel, The World Set Free, which appeared shortly before the First World War. In a 1924 article, Winston Churchill speculated about the possible military implications: "Might not a bomb no bigger than an orange be found to posses... | Wikipedia - History of nuclear weapons - Background |
Physicist Leo Szilard fled to London where, in 1934, he patented the idea of a nuclear chain reaction via neutrons. The patent also introduced the term critical mass to describe the minimum amount of material required to sustain the chain reaction and its potential to cause an explosion (British patent 630,726). The pa... | Wikipedia - History of nuclear weapons - Background |
Szilard subsequently assigned the patent to the British Admiralty so that it could be covered by the Official Secrets Act. This work of Szilard's was ahead of the time, five years before the public discovery of nuclear fission and eight years before a working nuclear reactor. When he coined the term neutron inducted ch... | Wikipedia - History of nuclear weapons - Background |
Despite this uncertainty, he correctly theorized uranium and thorium as primary candidates for such a reaction, along with beryllium which was later determined to be unnecessary in practice. Szilard joined with Enrico Fermi in developing the first uranium-fuelled nuclear reactor, Chicago Pile-1, which was activated at ... | Wikipedia - History of nuclear weapons - Background |
Lise Meitner and Otto Robert Frisch correctly interpreted these results as being due to the splitting of the uranium atom. Frisch confirmed this experimentally on January 13, 1939. They gave the process the name "fission" because of its similarity to the splitting of a cell into two new cells. | Wikipedia - History of nuclear weapons - Background |
Even before it was published, news of Meitner's and Frisch's interpretation crossed the Atlantic. In their second publication on nuclear fission in February of 1939, Hahn and Strassmann predicted the existence and liberation of additional neutrons during the fission process, opening up the possibility of a nuclear chai... | Wikipedia - History of nuclear weapons - Background |
The following year, they identified the active component of uranium as being the rare isotope uranium-235.Between 1939 and 1940, Joliot-Curie's team applied for a patent family covering different use cases of atomic energy, one (case III, in patent FR 971,324 - Perfectionnements aux charges explosives, meaning Improvem... | Wikipedia - History of nuclear weapons - Background |
When the nucleus of uranium-235 absorbs a neutron, it undergoes nuclear fission, releasing energy and, on average, 2.5 neutrons. Because uranium-235 releases more neutrons than it absorbs, it can support a chain reaction and so is described as fissile. Uranium-238, on the other hand, is not fissile as it does not norma... | Wikipedia - History of nuclear weapons - Background |
By the start of the war in September 1939, many scientists likely to be persecuted by the Nazis had already escaped. Physicists on both sides were well aware of the possibility of utilizing nuclear fission as a weapon, but no one was quite sure how it could be engineered. | Wikipedia - History of nuclear weapons - Background |
In August 1939, concerned that Germany might have its own project to develop fission-based weapons, Albert Einstein signed a letter to U.S. President Franklin D. Roosevelt warning him of the threat. | Wikipedia - History of nuclear weapons - Background |
Roosevelt responded by setting up the Uranium Committee under Lyman James Briggs but, with little initial funding ($6,000), progress was slow. It was not until the U.S. entered the war in December 1941 that Washington decided to commit the necessary resources to a top-secret high priority bomb project.Organized researc... | Wikipedia - History of nuclear weapons - Background |
The Maud Committee was set up following the work of Frisch and Rudolf Peierls who calculated uranium-235's critical mass and found it to be much smaller than previously thought which meant that a deliverable bomb should be possible. In the February 1940 Frisch–Peierls memorandum they stated that: "The energy liberated ... | Wikipedia - History of nuclear weapons - Background |
The size of this area is difficult to estimate, but it will probably cover the centre of a big city." Edgar Sengier, a director of Shinkolobwe Mine in the Congo which produced by far the highest quality uranium ore in the world, had become aware of uranium's possible use in a bomb. In late 1940, fearing that it might b... | Wikipedia - History of nuclear weapons - Background |
: 204 In September 1942, General Leslie Groves was appointed to lead the U.S. project which became known as the Manhattan Project. Two of his first acts were to obtain authorization to assign the highest priority AAA rating on necessary procurements, and to order the purchase of all 1,250 tons of the Shinkolobwe ore. | Wikipedia - History of nuclear weapons - Background |
The Tube Alloys project was quickly overtaken by the U.S. effort and after Roosevelt and Churchill signed the Quebec Agreement in 1943, it was relocated and amalgamated into the Manhattan Project.Szilard started to acquire high-quality graphite and uranium, which were the necessary materials for building a large-scale ... | Wikipedia - History of nuclear weapons - Background |
In the first decades of the 20th century, the term "pleomorphism" was used to refer to the idea that bacteria change morphology, biological systems, or reproductive methods dramatically according to environmental cues. This claim was controversial among microbiologists of the time, and split them into two schools: the ... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
Monomorphic theory, supported by Louis Pasteur, Rudolf Virchow, Ferdinand Cohn, and Robert Koch, emerged to become the dominant paradigm in modern medical science: it is now almost universally accepted that each bacterial cell is derived from a previously existing cell of practically the same size and shape. However it... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
He agreed with the monomorphic school of thought, but disagreed with some of the foundational microbiological beliefs that the prominent monomorphists Cohn and Koch held. Winogradsky published a literature review titled "The Doctrine of Pleomorphism in Bacteriology" in which he attempted to explicate the pleomorphic de... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
Winogradsky explained the perception of pleomorphic bacteria as bacteria progressing through different stages within a developmental cycle, thereby providing the fundamental structure for a theory of morphology based upon the concept of dynamic deviation from a morphological type, or biotype. While the pleomorphic deba... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
A hypothesis referred to as "Pleomorphic Provolution", a component of Stuart Grace's "Ambimorphic Paradigm", takes both of these theories into consideration.Although it has recently been shown that certain bacteria are capable of dramatically changing shape, pleomorphy remains a controversial concept. A well accepted e... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
The genera Corynebacterium and Coccobacillus have been designated as a pleomorphic genera, diphtheroid Bacilli have been classified as pleomorphic nosocomial bacteria. Additionally, in one study focused on agents involved in a non-infectious disease, pleomorphic bacteria were found to exist in the blood of healthy huma... | Wikipedia - Pleomorphism (microbiology) - Bacteria |
In the first decades of the 21st century, an increased interest for historical fiction has been noted. One of the most successful writers of historical novels is Hilary Mantel. Other writers of historical fiction include Philippa Gregory, Bernard Cornwell, Sarah Waters, Ken Follett, George Saunders, Shirley Hazzard and... | Wikipedia - Historical fiction - 21st century |
In the first decades of the nineteenth century there was increased demand for coal in Glasgow, for domestic and industrial purposes. There were limited local supplies, and the Monkland Canal had been bringing coal in from the Monklands pits. In 1826 the Monkland and Kirkintilloch Railway was opened to modernise the tra... | Wikipedia - Coatbridge Branch (NBR) - The coal railways |
Other so-called coal railways followed in the district: the Garnkirk and Glasgow Railway being the first line to reach Glasgow from the Monklands, opening in 1831. It was followed by the Wishaw and Coltness Railway, opening from 1833. The discovery of substantial reserves of blackband iron ore and the development of th... | Wikipedia - Coatbridge Branch (NBR) - The coal railways |
In the first decades of the nineteenth century, there was a considerable increase in coal and iron ore extraction, and of iron smelting, in the general area of Coatbridge and Airdrie, and improvements in the efficiency of the process of iron manufacture led to accelerating demand for coal and iron ore, which in turn em... | Wikipedia - Slamannan Railway - Origins |
In 1831–2 the Edinburgh and Dalkeith Railway opened, giving access from pits in the Eskbank and Dalhousie areas to Edinburgh and Leith. Coal and iron deposits were being worked on a small scale in the Slamannan area, about halfway between Airdrie and Linlithgow; it was then in Stirlingshire, now in Falkirk District. Se... | Wikipedia - Slamannan Railway - Origins |
It was to run from a junction with the Ballochney Railway near Arbuckle, north-east of Airdrie, to a wharf on the Union Canal at Causeway End (nowadays spelt Causewayend), 23 miles (38 km) from Edinburgh. Thus it would give transport access for pits on the line to Glasgow (over the Ballochney and Monkland and Kirkintil... | Wikipedia - Slamannan Railway - Origins |
In the first decades of the twentieth century, the work of the Rockefeller Foundation was decisive for the implementation of public health initiatives in Brazil, especially in the so-called public health movement. At that time, Brazilian eugenics was the same as public health, as expressed in the maxim "to sanitize is ... | Wikipedia - History of eugenics - Rockefeller Foundation in Brazil |
In the first decades, Coxeter and Petrie allowed "saddle" vertices with alternating ridges and valleys, enabling them to construct three infinite folded surfaces which they called regular skew polyhedra. Coxeter offered a modified Schläfli symbol {l,m|n} for these figures, with {l,m} implying the vertex figure, with m ... | Wikipedia - Regular polyhedra - Regular skew apeirohedra |
In the first definitive book on defence mechanisms, The Ego and the Mechanisms of Defence (1936), Anna Freud enumerated the ten defence mechanisms that appear in the works of her father, Sigmund Freud: repression, regression, reaction formation, isolation, undoing, projection, introjection, turning against one's own pe... | Wikipedia - Ego defenses - Theories and classifications |
Both Freuds studied defence mechanisms, but Anna spent more of her time and research on five main mechanisms: repression, regression, projection, reaction formation, and sublimation. All defence mechanisms are responses to anxiety and how the consciousness and unconscious manage the stress of a social situation. Repres... | Wikipedia - Ego defenses - Theories and classifications |
For example, if a wife is infatuated with a man who is not her husband, reaction formation may cause her to – rather than cheat – become obsessed with showing her husband signs of love and affection. Sublimation: seen as the most acceptable of the mechanisms, an expression of anxiety in socially acceptable waysOtto F. ... | Wikipedia - Ego defenses - Theories and classifications |
Borderline personality organization develops when the child cannot integrate helpful and harmful mental objects together. Kernberg views the use of primitive defence mechanisms as central to this personality organization. Primitive psychological defences are projection, denial, dissociation or splitting and they are ca... | Wikipedia - Ego defenses - Theories and classifications |
Also, devaluation and projective identification are seen as borderline defences.In George Eman Vaillant's (1977) categorization, defences form a continuum related to their psychoanalytical developmental level. They are classified into pathological, immature, neurotic and "mature" defences. Robert Plutchik's (1979) theo... | Wikipedia - Ego defenses - Theories and classifications |
According to his theory, reaction formation relates to joy (and manic features), denial relates to acceptance (and histrionic features), repression to fear (and passivity), regression to surprise (and borderline traits), compensation to sadness (and depression), projection to disgust (and paranoia), displacement to ang... | Wikipedia - Ego defenses - Theories and classifications |
Different theorists have different categorizations and conceptualizations of defence mechanisms. Large reviews of theories of defence mechanisms are available from Paulhus, Fridhandler and Hayes (1997) and Cramer (1991). The Journal of Personality published a special issue on defence mechanisms (1998). | Wikipedia - Ego defenses - Theories and classifications |
In the first demonstration of the Photoacoustic Doppler effect, a continuous wave diode laser was used in a photoacoustic microscopy setup with an ultrasonic transducer as the detector. The sample was a solution of absorbing particles moving through a tube. The tube was in a water bath containing scattering particlesFi... | Wikipedia - Photoacoustic Doppler effect - Experiment |
In a scattering medium, such as the experimental phantom, fewer photons reach the absorbers than in an optically clear medium. This affects the signal intensity but not the magnitude of the frequency shift. Another demonstrated feature of this technique is that it is capable of measuring flow direction relative to the ... | Wikipedia - Photoacoustic Doppler effect - Experiment |
In the first design of the Altair, the parts needed to make a complete machine would not fit on a single motherboard, and the machine consisted of four boards stacked on top of each other with stand-offs. Another problem facing Roberts was that the parts needed to make a truly useful computer were not available, or wou... | Wikipedia - MITS Altair - Description |
He then looked for a cheap source of connectors and came across a supply of 100-pin edge connectors. The S-100 bus was eventually acknowledged by the professional computer community and adopted as the IEEE-696 computer bus standard. The Altair bus consists of the pins of the Intel 8080 run out onto the backplane. | Wikipedia - MITS Altair - Description |
No particular level of thought went into the design, which led to disasters such as shorting from various power lines of differing voltages being located next to each other. Another oddity was that the system included two unidirectional 8-bit data buses, when the normal practice was for a single bidirectional bus (this... | Wikipedia - MITS Altair - Description |
The Altair shipped in a two-piece case. The backplane and power supply were mounted on a base plate, along with the front and rear of the box. The "lid" was shaped like a C, forming the top, left, and right sides of the box. | Wikipedia - MITS Altair - Description |
The front panel, which was inspired by the Data General Nova minicomputer, included a large number of toggle switches to feed binary data directly into the memory of the machine, and a number of red LEDs to read those values back out.Programming the Altair via the front panel could be a tedious and time-consuming proce... | Wikipedia - MITS Altair - Description |
The only output from the programs was the patterns of lights on the panel. Nevertheless, many were sold in this form. Development was already underway on additional cards, including a paper tape reader for storage, additional RAM cards, and an RS-232 interface to connect to a proper teletype terminal. | Wikipedia - MITS Altair - Description |
In the first developments of synthetic setae, polymers like polyimide, polypropylene and polydimethylsiloxane (PDMS) are frequently used since they are flexible and easily fabricated. Later, as nanotechnology rapidly developed, Carbon Nanotubes (CNTs) are preferred by most research groups and used in most recent projec... | Wikipedia - Synthetic setae - Materials |
In the first diagram clubs are trumps and South could claim all tricks on a crossruff were it not for the trump in East's hand. When the club jack is played, the entry-shifting squeeze comes to his rescue. If West sheds a heart, the jack is overtaken with the ace, a heart ruffed and North is left with the last trump an... | Wikipedia - Entry-shifting squeeze - Examples |
North's club ace ruffs the diamonds good and the South hand wins the last two tricks. The entry-shifting mechanism works also in No Trumps, as can be seen in the next example. As only five tricks out of remaining six cards are required, this is a squeeze without the count. | Wikipedia - Entry-shifting squeeze - Examples |
It is not possible to rectify the count as there are not enough communications between the two hands. The entry-shifting mechanism will overcome this though. South leads the ♦A and West has no good discard. | Wikipedia - Entry-shifting squeeze - Examples |
If he discards a spade, the ♦J is played and South continues with a spade to the ace and the spade eight. West returns a heart to South's ace, but the diamond king serves as an entry to the established spades. If West chooses to discard a heart, the diamond king is played and after ace of hearts and another heart, the ... | Wikipedia - Entry-shifting squeeze - Examples |
In the first diagram, White's rook is behind his passed pawn on the a-file, and the position is won for White. The winning technique is straightforward: Move the king towards the passed pawn. The defending king must also move that way, otherwise he will be forced to give up his rook for the pawn. If the attacking king ... | Wikipedia - Tarrasch rule - Rook behind own passed pawn: usually a win |
Once pawn moves are exhausted, then the defender runs out of options. If the defending rook retreats, then advance the pawn. The defender cannot keep up this strategy. | Wikipedia - Tarrasch rule - Rook behind own passed pawn: usually a win |
If the defending king sidesteps away from the pawn, the attacking king moves towards the pawn, and forces its advance. The defender will have to give up his rook. So the only option is for the defending king to move towards the pawn. | Wikipedia - Tarrasch rule - Rook behind own passed pawn: usually a win |
The attacking king penetrates the kingside pawn structure as far as possible. If the defender wins the passed pawn, an exchange of rooks ensues and the resulting pawn ending is an easy win for the attacker. | Wikipedia - Tarrasch rule - Rook behind own passed pawn: usually a win |
At the right moment, the attacking rook abandons the pawn and joins in the attack on the kingside pawns.The 34th game of the 1927 World Championship match between Alekhine and Capablanca is a classic example of the technique (or see annotated text). The position is after White's 54.Ra4. White won on move 82. | Wikipedia - Tarrasch rule - Rook behind own passed pawn: usually a win |
In the first drawing the current (I, red arrows) in both wires is in the same direction. The current in the lefthand wire creates a circular magnetic field (B, green lines) which passes through the other wire. From the right hand rule the field lines pass through the wire in an upward direction. From Faraday's law of i... | Wikipedia - Proximity effect (electromagnetism) - Currents in the same direction |
These are called eddy currents. On the lefthand side nearest to the other wire (1) the eddy current is in the opposite direction to the main current (big pink arrow) in the wire, so it subtracts from the main current, reducing it. On the righthand side (2) the eddy current is in the same direction as the main current s... | Wikipedia - Proximity effect (electromagnetism) - Currents in the same direction |
The net effect is to redistribute the current in the cross section of the wire into a thin strip on the side facing away from the other wire. The current distribution is shown by the red arrows and color gradient (3) on the cross section, with blue areas indicating low current and green, yellow, and red indicating high... | Wikipedia - Proximity effect (electromagnetism) - Currents in the same direction |
In the first edition of Advanced Dungeons & Dragons, "Cacodemon" is a seventh level magic-user spell. It was used to summon a type IV, V, or VI demon to the player character's location in the game world. The spell was omitted from the early versions of the second edition of the game, and was later revised in the Planes... | Wikipedia - Cacodemon - Games |
In the fantasy video game Baldur's Gate II: Shadows of Amn, the BioWare Infinity Engine equivalent of the "Cacodemon" spell is known as "Cacofiend". In the fantasy world Glorantha, Cacodemon is the god of lawlessness and ogres. In the Doom video game series developed by id Software, Cacodemons are an enemy, depicted as... | Wikipedia - Cacodemon - Games |
They have appeared in every game of the series. In Final Fantasy XI MMORPG, the Terrestrial Avatar Diabolos uses a special attack called "Cacodemonia". In Anarchy Online MMORPG, a pet that one of the professions can summon is the Cacodemon. | Wikipedia - Cacodemon - Games |
In Wizardry V: Heart of the Maelstrom, Cacodaemons are large red demons encountered on floor 777. In the Pathfinder Roleplaying Game, cacodaemons are many-eyed, tadpolish daemons used as pets by greater ones and as familiars by spellcasters. In Smite, there is a set of three Cacodemon skins for the playable God Ymir. | Wikipedia - Cacodemon - Games |
In Magic: The Gathering, Dread Cacodemon is a card from the Commander expansion. In Dungeon Crawl Stone Soup, Cacodemons are large, yellow demons who attack with projectiles and hexes. In Final Fantasy XIV: Endwalker, a "kakodaimon" is part of a pivotal combat encounter. | Wikipedia - Cacodemon - Games |
In the first edition of Civic Biology, Hunter briefly discusses eugenics on one page of the 432 page textbook. Along with many other evolutionary biologists, Hunter embraced the idea of eugenics as a social doctrine. It was a popular idea in the early 20th century, and several states had enacted laws to compel the sexu... | Wikipedia - Civic Biology - Eugenics |
In the first edition of The Theatre of the Absurd, Esslin quotes the French philosopher Albert Camus's essay "Myth of Sisyphus", as it uses the word "absurdity" to describe the human situation: "In a universe that is suddenly deprived of illusions and of light, man feels a stranger. … This divorce between man and his l... | Wikipedia - Absurd theatre - Origin |
In the first edition of the American Psychiatric Association's Diagnostic and Statistical Manual (DSM-I), a disorder of impulsive aggression was referred to as a passive-aggressive personality type (aggressive type). This construct was characterized by a "persistent reaction to frustration are "generally excitable, agg... | Wikipedia - Intermittent Explosive Disorder - History |
The severity and frequency of aggressive behavior required for the diagnosis were clearly operationalized, the aggressive acts were required to be impulsive in nature, subjective distress was required to precede the explosive outbursts, and the criteria allowed for comorbid diagnoses with borderline personality disorde... | Wikipedia - Intermittent Explosive Disorder - History |
In the DSM-IV, physical aggression was required to meet the criteria for the disorder, but these criteria were modified in the DSM-5 to include verbal aggression and non-destructive/noninjurious physical aggression. The listing was also updated to specify frequency criteria. | Wikipedia - Intermittent Explosive Disorder - History |
Further, aggressive outbursts are now required to be impulsive in nature and must cause marked distress, impairment, or negative consequences for the individual. Individuals must be at least six years old to receive the diagnosis. The text also clarified the disorder's relationship to other disorders such as ADHD and d... | Wikipedia - Intermittent Explosive Disorder - History |
In the first edition of the Logical Investigations, under the influence of Brentano, Husserl describes his position as "descriptive psychology." Husserl analyzes the intentional structures of mental acts and how they are directed at both real and ideal objects. The first volume of the Logical Investigations, the Proleg... | Wikipedia - Transcendental constitutive phenomenology - Logical Investigations (1900/1901) |
Husserl establishes a separate field for research in logic, philosophy, and phenomenology, independently from the empirical sciences. "Pre-reflective self-consciousness" is Shaun Gallagher and Dan Zahavi's term for Husserl's (1900/1901) idea that self-consciousness always involves a self-appearance or self-manifestatio... | Wikipedia - Transcendental constitutive phenomenology - Logical Investigations (1900/1901) |
In the first edition of the official Latin nomenclature (Nomina Anatomica, renamed in 1998 as Terminologia Anatomica), the Latin expression ligamenta cruciata was used, similar to the expression cruciate ligaments currently in use in English. In classical Latin the verb cruciare is derived from crux, meaning cross. It ... | Wikipedia - Cruciate ligament - Etymology |
In the first edition, Irving estimated that the two Royal Air Force raids and the first U.S. Army Air Forces raid combined were "estimated authoritatively to have killed more than 135,000 of the population ..." and the "documentation suggests very strongly that the figure was certainly between a minimum of 100,000 and ... | Wikipedia - The Destruction of Dresden - Deaths |
In the 1995 edition, the three raids "cost the lives of between fifty and one hundred thousand inhabitants....". Richard J. Evans states that "Elsewhere he dropped the lower figure and said the attack cost 'up to a hundred thousand people their lives'".According to Richard J. Evans, an expert witness for the defence at... | Wikipedia - The Destruction of Dresden - Deaths |
In the first edition, all artifacts are classed as miscellaneous magic items, even ones that are weapons, armor, or rings. Each artifact has a certain number of Minor, Major, and Prime Powers, and of Minor, Major, and Side Effects which trigger when the item is acquired, or its Major and Prime Powers are used. The powe... | Wikipedia - Bag of Holding - 1st edition Advanced Dungeons & Dragons |
In the first electromechanical switching systems, the current pulses generated by the rotary dial on the local loop directly operated electrical stepping switches at the central office. The mechanical nature of these relays generally limited the speed of operation, the pulsing rate, to ten pulses per second. The specif... | Wikipedia - Dial pulse - Pulse rate and coding |
Exceptions to this are Sweden, with one pulse for 0, two pulses for 1, and so on, and New Zealand, with ten pulses for 0, nine pulses for 1, etc. Oslo, the capital city of Norway, used the New Zealand system, but the rest of the country did not. Systems that used this encoding of the ten digits in a sequence of up to t... | Wikipedia - Dial pulse - Pulse rate and coding |
These included access lines to the panel switch in the 1920s, crossbar systems, the later version (7A2) of the rotary system, and the earlier 1970s stored program control exchanges. In some telephones, the pulses may be heard in the receiver as clicking sounds. However, in general, such effects were undesirable and tel... | Wikipedia - Dial pulse - Pulse rate and coding |
In the first electronic keyboards in the early 1970s, the key switches were individual switches inserted into holes in metal frames. These keyboards cost from 80 to 120 USD and were used in mainframe data terminals. The most popular switch types were reed switches (contacts enclosed in a vacuum in a glass capsule, affe... | Wikipedia - Computer keyboards - Key switches |
There was simply a sponge pad with a conductive-coated Mylar plastic sheet on the switch plunger, and two half-moon trace patterns on the printed circuit board below. As the key was depressed, the capacitance between the plunger pad and the patterns on the PCB below changed, which was detected by integrated circuits (I... | Wikipedia - Computer keyboards - Key switches |
Prices of $60 for keyboards were achieved, and Key Tronic rapidly became the largest independent keyboard manufacturer. Meanwhile, IBM made their own keyboards, using their own patented technology: Keys on older IBM keyboards were made with a "buckling spring" mechanism, in which a coil spring under the key buckles und... | Wikipedia - Computer keyboards - Key switches |
Over time, less key travel was accepted in the market, finally landing on 0.110 inches (2.79 mm). Coincident with this, Key Tronic was the first company to introduce a keyboard that was only about one inch thick. | Wikipedia - Computer keyboards - Key switches |
And now keyboards measure only about a half-inch thick. Keytops are an important element of keyboards. | Wikipedia - Computer keyboards - Key switches |
In the beginning, keyboard keytops had a "dish shape" on top, like typewriters before them. Keyboard key legends must be extremely durable over tens of millions of depressions, since they are subjected to extreme mechanical wear from fingers and fingernails, and subject to hand oils and creams, so engraving and filling... | Wikipedia - Computer keyboards - Key switches |
But, to save cost, other methods were explored, such as sublimation printing and laser engraving, both methods which could be used to print a whole keyboard at the same time. Initially, sublimation printing, where a special ink is printed onto the keycap surface and the application of heat causes the ink molecules to p... | Wikipedia - Computer keyboards - Key switches |
But one problem with sublimation or laser printing was that the processes took too long and only dark legends could be printed on light-colored keys. On another note, IBM was unique in using separate shells, or "keycaps", on keytop bases. This might have made their manufacturing of different keyboard layouts more flexi... | Wikipedia - Computer keyboards - Key switches |
Three final mechanical technologies brought keyboards to where they are today, driving the cost well under $10: "Monoblock" keyboard designs were developed where individual switch housings were eliminated and a one-piece "monoblock" housing used instead. This was possible because of molding techniques that could provid... | Wikipedia - Computer keyboards - Key switches |
This technology came from flat-panel switch membranes, where the switch contacts are printed inside of a top and bottom layer, with a spacer layer in between, so that when pressure is applied to the area above, a direct electrical contact is made. The membrane layers can be printed by very-high volume, low-cost "reel-t... | Wikipedia - Computer keyboards - Key switches |
Greasing or oiling switch plungers was undesirable because it would attract dirt over time which would eventually affect the feel and even bind the key switches (although keyboard manufacturers would sometimes sneak this into their keyboards, especially if they could not control the tolerances of the key plungers and h... | Wikipedia - Computer keyboards - Key switches |
In common use, the term "mechanical keyboard" refers to a keyboard with individual mechanical key switches, each of which contains a fully encased plunger with a spring below it and metallic electrical contacts on a side. The plunger sits on the spring and the key will often close the contacts when the plunger is press... | Wikipedia - Computer keyboards - Key switches |
In the first enantioselective synthesis of (+)-Griseofulvin, a potent antifungal agent, a Curtin–Hammett situation was observed. A key step in the synthesis is the rhodium-catalyzed formation of an oxonium ylide, which then undergoes a sigmatropic rearrangement en route to the desired product. However, the substrate c... | Wikipedia - Curtin–Hammett principle - Synthesis of (+)-griseofulvin |
If the ortho-methoxy group undergoes oxonium ylide formation, a 1,4-methyl shift can then generate an undesired product. The oxonium ylide formed from the other ortho-alkoxy group is primed to undergo a sigmatropic rearrangement to yield the desired compound. Pirrung and coworkers reported complete selectivity for the... | Wikipedia - Curtin–Hammett principle - Synthesis of (+)-griseofulvin |
In the first episode Richard Dawkins explains the basic mechanisms of natural selection, and tells the story of how Charles Darwin developed his theory. He teaches a year 11 science class about evolution, which many of the students are reluctant to accept. He then takes them to the Jurassic Coast in Dorset to search fo... | Wikipedia - The Genius of Charles Darwin - Part 1: Life, Darwin & Everything |
In the first episode of series 20, Clarkson, Hammond and May revealed their new Reasonably Priced Car: a Vauxhall Astra 1.6 Tech Line. In similar fashion to earlier "new starts", an open day was held for multiple stars to drive the car. Following the abrupt end of Series 22 as a result of Clarkson's dismissal from the ... | Wikipedia - Top gear test track - Vauxhall Astra (2013–2015) |
In the first episode of the series, "The Eleventh Hour", Prisoner Zero tells the Doctor, "The universe is cracked. The Pandorica will open. Silence will fall". The Pandorica was also mentioned by River in "Flesh and Stone" as the next time she would meet him, and the Doctor dismissed the Pandorica as a fairy tale. | Wikipedia - The Pandorica Opens - Continuity |
In River's timeline this takes place before "The Time of Angels"/"Flesh and Stone". The painting of the TARDIS explosion passes through several characters from previous episodes: the painting is created by Vincent van Gogh (Tony Curran) after his meeting with the Doctor ("Vincent and the Doctor"). The painting is found... | Wikipedia - The Pandorica Opens - Continuity |
In the first episode of the series, a small group of misfits are kept behind from a Space Academy field trip. Nearby, an odd bird-like alien ship appears, and Harlan Band decides to sneak onto it; the other students, all of whom are younger and much less troublesome, follow Harlan onto the ship. During their exploratio... | Wikipedia - Space Cases - Synopsis |
One of the students accidentally charges the engines, hurtling the ship off into a spatial rift. By the time everyone figures out that only the children who bonded to the ship can actually control it, the ship has stopped several light years away from the Academy. They set off on a return trip which would take them at ... | Wikipedia - Space Cases - Synopsis |
In the first episode, Cox considers the fundamental nature of time while pondering the ruins at Chankillo in Peru. He explores the familiarly brief cycles of time that define the lives of humans on Earth (such as days, months, and years), and compares them to the cycles of time on a cosmically universal scale (such as ... | Wikipedia - Wonders of the Universe - 1. "Destiny" |
In the first era (1st–6th editions, 1768–1826), the Britannica was managed and published by its founders, Colin Macfarquhar and Andrew Bell, by Archibald Constable, and by others. The Britannica was first published between December 1768 and 1771 in Edinburgh as the Encyclopædia Britannica, or, A Dictionary of Arts and ... | Wikipedia - Encyclopaedia Britannica - 1768–1826 |
It went on sale 10 December.The Britannica of this period was primarily a Scottish enterprise, and it is one of the most enduring legacies of the Scottish Enlightenment. In this era, the Britannica moved from being a three-volume set (1st edition) compiled by one young editor—William Smellie—to a 20-volume set written ... | Wikipedia - Encyclopaedia Britannica - 1768–1826 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.