lukasellinger/wiki_dump_2024-07-08 · Datasets at Hugging Face

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electric motor

Elektromotor (wiktionary)

From elektro- +‎ Motor. Elektromotor m (mixed, genitive Elektromotors, plural Elektromotoren) electric motor “Elektromotor” in Duden online “Elektromotor” in Digitales Wörterbuch der deutschen Sprache

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electric motor

elektromotor (wiktionary)

From elektro- +‎ motor. IPA(key): [ˈɛlɛktromotor] Rhymes: -otor elektromotor m inan electric motor See elektro- and motiv elektromotor in Příruční slovník jazyka českého, 1935–1957 elektromotor in Slovník spisovného jazyka českého, 1960–1971, 1989 elektromotor in Internetová jazyková příručka electromotor (superseded) From elektro- +‎ motor. IPA(key): /eːˈlɛk.troːˌmoː.tɔr/ Hyphenation: elek‧tro‧mo‧tor elektromotor m (plural elektromotoren) An electric motor. From elektro- +‎ motor. elektromotor m (definite singular elektromotoren, indefinite plural elektromotorer, definite plural elektromotorene) an electric motor elmotor elektrisk motor “elektromotor” in The Bokmål Dictionary. From elektro- +‎ motor. elektromotor m (definite singular elektromotoren, indefinite plural elektromotorar, definite plural elektromotorane) an electric motor elmotor elektrisk motor “elektromotor” in The Nynorsk Dictionary.

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electric motor

electric motor (wiktionary)

electric motor (plural electric motors) A motor that converts electrical energy into kinetic energy. generator

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electric motor

Electric motor (wikipedia)

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be brushed or brushless, single-phase, two-phase, or three-phase, axial or radial flux, and may be air-cooled or liquid-cooled. Standardized motors provide power for industrial use. The largest are used for ship propulsion, pipeline compression and pumped-storage applications, with output exceeding 100 megawatts. Applications include industrial fans, blowers and pumps, machine tools, household appliances, power tools, vehicles, and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction. Electric motors produce linear or rotary force (torque) intended to propel some external mechanism. This makes them a type of actuator. They are generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Solenoids also convert electrical power to mechanical motion, but over only a limited distance. == History == === Early motors === Before modern electromagnetic motors, experimental motors that worked by electrostatic force were investigated. The first electric motors were simple electrostatic devices described in experiments by Scottish monk Andrew Gordon and American experimenter Benjamin Franklin in the 1740s. The theoretical principle behind them, Coulomb's law, was discovered but not published, by Henry Cavendish in 1771. This law was discovered independently by Charles-Augustin de Coulomb in 1785, who published it so that it is now known with his name. Due to the difficulty of generating the high voltages they required, electrostatic motors were never used for practical purposes. The invention of the electrochemical battery by Alessandro Volta in 1799 made possible the production of persistent electric currents. Hans Christian Ørsted discovered in 1820 that an electric current creates a magnetic field, which can exert a force on a magnet. It only took a few weeks for André-Marie Ampère to develop the first formulation of the electromagnetic interaction and present the Ampère's force law, that described the production of mechanical force by the interaction of an electric current and a magnetic field. The first demonstration of the effect with a rotary motion was given by Michael Faraday on 3 September 1821 in the basement of the Royal Institution. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet (PM) was placed. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. Faraday published the results of his discovery in the Quarterly Journal of Science, and sent copies of his paper along with pocket-sized models of his device to colleagues around the world so they could also witness the phenomenon of electromagnetic rotations. This motor is often demonstrated in physics experiments, substituting brine for (toxic) mercury. Barlow's wheel was an early refinement to this Faraday demonstration, although these and similar homopolar motors remained unsuited to practical application until late in the century. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils. After Jedlik solved the technical problems of continuous rotation with the invention of the commutator, he called his early devices "electromagnetic self-rotors". Although they were used only for teaching, in 1828 Jedlik demonstrated the first device to contain the three main components of practical DC motors: the stator, rotor and commutator. The device employed no permanent magnets, as the magnetic fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. === DC motors === The first commutator DC electric motor capable of turning machinery was invented by English scientist William Sturgeon in 1832. Following Sturgeon's work, a commutator-type direct-current electric motor was built by American inventors Thomas Davenport and Emily Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools and a printing press. Due to the high cost of primary battery power, the motors were commercially unsuccessful and bankrupted the Davenports. Several inventors followed Sturgeon in the development of DC motors, but all encountered the same battery cost issues. As no electricity distribution system was available at the time, no practical commercial market emerged for these motors. After many other more or less successful attempts with relatively weak rotating and reciprocating apparatus Prussian/Russian Moritz von Jacobi created the first real rotating electric motor in May 1834. It developed remarkable mechanical output power. His motor set a world record, which Jacobi improved four years later in September 1838. His second motor was powerful enough to drive a boat with 14 people across a wide river. It was also in 1839/40 that other developers managed to build motors with similar and then higher performance. In 1827–1828, Jedlik built a device using similar principles to those used in his electromagnetic self-rotors that was capable of useful work. He built a model electric vehicle that same year. A major turning point came in 1864, when Antonio Pacinotti first described the ring armature (although initially conceived in a DC generator, i.e. a dynamo). This featured symmetrically grouped coils closed upon themselves and connected to the bars of a commutator, the brushes of which delivered practically non-fluctuating current. The first commercially successful DC motors followed the developments by Zénobe Gramme who, in 1871, reinvented Pacinotti's design and adopted some solutions by Werner Siemens. A benefit to DC machines came from the discovery of the reversibility of the electric machine, which was announced by Siemens in 1867 and observed by Pacinotti in 1869. Gramme accidentally demonstrated it on the occasion of the 1873 Vienna World's Fair, when he connected two such DC devices up to 2 km from each other, using one of them as a generator and the other as motor. The drum rotor was introduced by Friedrich von Hefner-Alteneck of Siemens & Halske to replace Pacinotti's ring armature in 1872, thus improving the machine efficiency. The laminated rotor was introduced by Siemens & Halske the following year, achieving reduced iron losses and increased induced voltages. In 1880, Jonas Wenström provided the rotor with slots for housing the winding, further increasing the efficiency. In 1886, Frank Julian Sprague invented the first practical DC motor, a non-sparking device that maintained relatively constant speed under variable loads. Other Sprague electric inventions about this time greatly improved grid electric distribution (prior work done while employed by Thomas Edison), allowed power from electric motors to be returned to the electric grid, provided for electric distribution to trolleys via overhead wires and the trolley pole, and provided control systems for electric operations. This allowed Sprague to use electric motors to invent the first electric trolley system in 1887–88 in Richmond, Virginia, the electric elevator and control system in 1892, and the electric subway with independently powered centrally-controlled cars. The latter were first installed in 1892 in Chicago by the South Side Elevated Railroad, where it became popularly known as the "L". Sprague's motor and related inventions led to an explosion of interest and use in electric motors for industry. The development of electric motors of acceptable efficiency was delayed for several decades by failure to recognize the extreme importance of an air gap between the rotor and stator. Efficient designs have a comparatively small air gap. The St. Louis motor, long used in classrooms to illustrate motor principles, is inefficient for the same reason, as well as appearing nothing like a modern motor. Electric motors revolutionized industry. Industrial processes were no longer limited by power transmission using line shafts, belts, compressed air or hydraulic pressure. Instead, every machine could be equipped with its own power source, providing easy control at the point of use, and improving power transmission efficiency. Electric motors applied in agriculture eliminated human and animal muscle power from such tasks as handling grain or pumping water. Household uses (like in washing machines, dishwashers, fans, air conditioners and refrigerators (replacing ice boxes) of electric motors reduced heavy labor in the home and made higher standards of convenience, comfort and safety possible. Today, electric motors consume more than half of the electric energy produced in the US. === AC motors === In 1824, French physicist François Arago formulated the existence of rotating magnetic fields, termed Arago's rotations, which, by manually turning switches on and off, Walter Baily demonstrated in 1879 as in effect the first primitive induction motor. In the 1880s many inventors were trying to develop workable AC motors because AC's advantages in long-distance high-voltage transmission were offset by the inability to operate motors on AC. The first alternating-current commutatorless induction motor was invented by Galileo Ferraris in 1885. Ferraris was able to improve his first design by producing more advanced setups in 1886. In 1888, the Royal Academy of Science of Turin published Ferraris's research detailing the foundations of motor operation, while concluding at that time that "the apparatus based on that principle could not be of any commercial importance as motor." Possible industrial development was envisioned by Nikola Tesla, who invented independently his induction motor in 1887 and obtained a patent in May 1888. In the same year, Tesla presented his paper A New System of Alternate Current Motors and Transformers to the AIEE that described three patented two-phase four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor, another with a wound rotor forming a self-starting induction motor, and the third a true synchronous motor with separately excited DC supply to rotor winding. One of the patents Tesla filed in 1887, however, also described a shorted-winding-rotor induction motor. George Westinghouse, who had already acquired rights from Ferraris (US$1,000), promptly bought Tesla's patents (US$60,000 plus US$2.50 per sold hp, paid until 1897), employed Tesla to develop his motors, and assigned C.F. Scott to help Tesla; however, Tesla left for other pursuits in 1889. The constant speed AC induction motor was found not to be suitable for street cars, but Westinghouse engineers successfully adapted it to power a mining operation in Telluride, Colorado in 1891. Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, but these early Westinghouse motors were two-phase motors with wound rotors. B.G. Lamme later developed a rotating bar winding rotor. Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the three-phase induction motor in 1889, of both types cage-rotor and wound rotor with a starting rheostat, and the three-limb transformer in 1890. After an agreement between AEG and Maschinenfabrik Oerlikon, Doliwo-Dobrowolski and Charles Eugene Lancelot Brown developed larger models, namely a 20-hp squirrel cage and a 100-hp wound rotor with a starting rheostat. These were the first three-phase asynchronous motors suitable for practical operation. Since 1889, similar developments of three-phase machinery were started Wenström. At the 1891 Frankfurt International Electrotechnical Exhibition, the first long distance three-phase system was successfully presented. It was rated 15 kV and extended over 175 km from the Lauffen waterfall on the Neckar river. The Lauffen power station included a 240 kW 86 V 40 Hz alternator and a step-up transformer while at the exhibition a step-down transformer fed a 100-hp three-phase induction motor that powered an artificial waterfall, representing the transfer of the original power source. The three-phase induction is now used for the vast majority of commercial applications. Mikhail Dolivo-Dobrovolsky claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work. The General Electric Company began developing three-phase induction motors in 1891. By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design, later called the squirrel-cage rotor. Induction motor improvements flowing from these inventions and innovations were such that a 100-horsepower induction motor currently has the same mounting dimensions as a 7.5-horsepower motor in 1897. === Twenty-first century === In 2022, electric motor sales were estimated to be 800 million units, increasing by 10% annually. Electric motors consume ≈50% of the world's electricity. Since the 1980s, the market share of DC motors has declined in favor of AC motors.: 89 == Components == An electric motor has two mechanical parts: the rotor, which moves, and the stator, which does not. Electrically, the motor consists of two parts, the field magnets and the armature, one of which is attached to the rotor and the other to the stator. Together they form a magnetic circuit. The magnets create a magnetic field that passes through the armature. These can be electromagnets or permanent magnets. The field magnet is usually on the stator and the armature on the rotor, but these may be reversed. === Rotor === The rotor is the moving part that delivers the mechanical power. The rotor typically holds conductors that carry currents, on which the magnetic field of the stator exerts force to turn the shaft. Some rotors carry permanent magnets. Permanent magnets offer high efficiency over a large operating speed and power range. === Stator === The stator surrounds the rotor, and usually holds field magnets, which are either electromagnets (wire windings around a ferromagnetic iron core) or permanent magnets. These create a magnetic field that passes through the rotor armature, exerting force on the rotor windings. The stator core is made up of many thin metal sheets that are insulated from each other, called laminations. These laminations are made of electrical steel, which has a specified magnetic permeability, hysteresis, and saturation. Laminations reduce losses that would result from induced circulating eddy currents that would flow if a solid core were used. Mains powered AC motors typically immobilize the wires within the windings by impregnating them with varnish in a vacuum. This prevents the wires in the winding from vibrating against each other which would abrade the wire insulation and cause premature failures. Resin-packed motors, used in deep well submersible pumps, washing machines, and air conditioners, encapsulate the stator in plastic resin to prevent corrosion and/or reduce conducted noise. === Gap === An air gap between the stator and rotor allows it to turn. The width of the gap has a significant effect on the motor's electrical characteristics. It is generally made as small as possible, as a large gap weakens performance. Conversely, gaps that are too small may create friction in addition to noise. === Armature === The armature consists of wire windings on a ferromagnetic core. Electric current passing through the wire causes the magnetic field to exert a force (Lorentz force) on it, turning the rotor. Windings are coiled wires, wrapped around a laminated, soft, iron, ferromagnetic core so as to form magnetic poles when energized with current. Electric machines come in salient- and nonsalient-pole configurations. In a salient-pole motor the rotor and stator ferromagnetic cores have projections called poles that face each other. Wire is wound around each pole below the pole face, which become north or south poles when current flows through the wire. In a nonsalient-pole (distributed field or round-rotor) motor, the ferromagnetic core is a smooth cylinder, with the windings distributed evenly in slots around the circumference. Supplying alternating current in the windings creates poles in the core that rotate continuously. A shaded-pole motor has a winding around part of the pole that delays the phase of the magnetic field for that pole. === Commutator === A commutator is a rotary electrical switch that supplies current to the rotor. It periodically reverses the flow of current in the rotor windings as the shaft rotates. It consists of a cylinder composed of multiple metal contact segments on the armature. Two or more electrical contacts called "brushes" made of a soft conductive material like carbon press against the commutator. The brushes make sliding contact with successive commutator segments as the rotator turns, supplying current to the rotor. The windings on the rotor are connected to the commutator segments. The commutator reverses the current direction in the rotor windings with each half turn (180°), so the torque applied to the rotor is always in the same direction. Without this reversal, the direction of torque on each rotor winding would reverse with each half turn, stopping the rotor. Commutated motors have been mostly replaced by brushless motors, permanent magnet motors, and induction motors. === Shaft === The motor shaft extends outside of the motor, where it satisfies the load. Because the forces of the load are exerted beyond the outermost bearing, the load is said to be overhung. === Bearings === The rotor is supported by bearings, which allow the rotor to turn on its axis by transferring the force of axial and radial loads from the shaft to the motor housing. == Inputs == === Power supply === A DC motor is usually supplied through a split ring commutator as described above. AC motors' commutation can be achieved using either a slip ring commutator or external commutation. It can be fixed-speed or variable-speed control type, and can be synchronous or asynchronous. Universal motors can run on either AC or DC. === Control === DC motors can be operated at variable speeds by adjusting the voltage applied to the terminals or by using pulse-width modulation (PWM). AC motors operated at a fixed speed are generally powered directly from the grid or through motor soft starters. AC motors operated at variable speeds are powered with various power inverter, variable-frequency drive or electronic commutator technologies. The term electronic commutator is usually associated with self-commutated brushless DC motor and switched reluctance motor applications. == Types == Electric motors operate on one of three physical principles: magnetism, electrostatics and piezoelectricity. In magnetic motors, magnetic fields are formed in both the rotor and the stator. The product between these two fields gives rise to a force and thus a torque on the motor shaft. One or both of these fields changes as the rotor turns. This is done by switching the poles on and off at the right time, or varying the strength of the pole. Motors operate on either DC or AC current (or either). AC motors can be either asynchronous or synchronous. Synchronous motors require the rotor to turn at the same speed as the stator's rotating field. Asynchronous rotors relax this constraint. A fractional-horsepower motor either has a rating below about 1 horsepower (0.746 kW), or is manufactured with a frame size smaller than a standard 1 HP motor. Many household and industrial motors are in the fractional-horsepower class. Notes: 1. Rotation is independent of the frequency of the AC voltage. 2. Rotation is equal to synchronous speed (motor-stator-field speed). 3. In SCIM, fixed-speed operation rotation is equal to synchronous speed, less slip speed. 4. In non-slip energy-recovery systems, WRIM is usually used for motor-starting but can be used to vary load speed. 5. Variable-speed operation. 6. Whereas induction- and synchronous-motor drives are typically with either six-step or sinusoidal-waveform output, BLDC-motor drives are usually with trapezoidal-current waveform; the behavior of both sinusoidal and trapezoidal PM machines is, however, identical in terms of their fundamental aspects. 7. In variable-speed operation, WRIM is used in slip-energy recovery and double-fed induction-machine applications. 8. A cage winding is a short-circuited squirrel-cage rotor, a wound winding is connected externally through slip rings. 9. Mostly single-phase with some three-phase. Abbreviations: BLAC – Brushless AC BLDC – Brushless DC BLDM – Brushless DC motor EC – Electronic commutator PM – Permanent magnet IPMSM – Interior permanent-magnet synchronous motor PMSM – Permanent magnet synchronous motor SPMSM – Surface permanent magnet synchronous motor SCIM – Squirrel-cage induction motor SRM – Switched reluctance motor SyRM – Synchronous reluctance motor VFD – Variable-frequency drive WRIM – Wound-rotor induction motor WRSM – Wound-rotor synchronous motor LRA – Locked-rotor amps: The current you can expect under starting conditions when you apply full voltage. It occurs instantly during start-up. RLA – Rated-load amps: The maximum current a motor should draw under any operating conditions. Often mistakenly called running-load amps, which leads people to believe, incorrectly, that the motor should always pull these amps. FLA – Full-load amps: Changed in 1976 to "RLA – rated-load amps". == Self-commutated motor == === Brushed DC motor === Most DC motors are small permanent magnet (PM) types. They contain a brushed internal mechanical commutation to reverse motor windings' current in synchronism with rotation. ==== Electrically excited DC motor ==== A commutated DC motor has a set of rotating windings wound on an armature mounted on a rotating shaft. The shaft also carries the commutator. Thus, every brushed DC motor has AC flowing through its windings. Current flows through one or more pairs of brushes that touch the commutator; the brushes connect an external source of electric power to the rotating armature. The rotating armature consists of one or more wire coils wound around a laminated, magnetically "soft" ferromagnetic core. Current from the brushes flows through the commutator and one winding of the armature, making it a temporary magnet (an electromagnet). The magnetic field produced interacts with a stationary magnetic field produced by either PMs or another winding (a field coil), as part of the motor frame. The force between the two magnetic fields rotates the shaft. The commutator switches power to the coils as the rotor turns, keeping the poles from ever fully aligning with the magnetic poles of the stator field, so that the rotor keeps turning as long as power is applied. Many of the limitations of the classic commutator DC motor are due to the need for brushes to maintain contact with the commutator, creating friction. The brushes create sparks while crossing the insulating gaps between commutator sections. Depending on the commutator design, the brushes may create short circuits between adjacent sections—and hence coil ends. Furthermore, the rotor coils' inductance causes the voltage across each to rise when its circuit opens, increasing the sparking. This sparking limits the maximum speed of the machine, as too-rapid sparking will overheat, erode, or even melt the commutator. The current density per unit area of the brushes, in combination with their resistivity, limits the motor's output. Crossing the gaps also generates electrical noise; sparking generates RFI. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance or replacement. The commutator assembly on a large motor is a costly element, requiring precision assembly of many parts. On small motors, the commutator is usually permanently integrated into the rotor, so replacing it usually requires replacing the rotor. While most commutators are cylindrical, some are flat, segmented discs mounted on an insulator. Large brushes create a large contact area, which maximizes motor output, while small brushes have low mass to maximize the speed at which the motor can run without excessive sparking. (Small brushes are desirable for their lower cost.) Stiffer brush springs can be used to make brushes of a given mass work at a higher speed, despite greater friction losses (lower efficiency) and accelerated brush and commutator wear. Therefore, DC motor brush design entails a trade-off between output power, speed, and efficiency/wear. DC machines are defined as follows: Armature circuit – A winding that carries the load, either stationary or rotating. Field circuit – A set of windings that produces a magnetic field. Commutation: A mechanical technique in which rectification can be achieved, or from which DC can be derived. The five types of brushed DC motor are: Shunt-wound Series-wound Compound (two configurations): Cumulative compound Differentially compounded Permanent magnet (not shown) Separately excited (not shown). ==== Permanent magnet ==== A permanent magnet (PM) motor does not have a field winding on the stator frame, relying instead on PMs to provide the magnetic field. Compensating windings in series with the armature may be used on large motors to improve commutation under load. This field is fixed and cannot be adjusted for speed control. PM fields (stators) are convenient in miniature motors to eliminate the power consumption of the field winding. Most larger DC motors are of the "dynamo" type, which have stator windings. Historically, PMs could not be made to retain high flux if they were disassembled; field windings were more practical to obtain the needed flux. However, large PMs are costly, as well as dangerous and difficult to assemble; this favors wound fields for large machines. To minimize overall weight and size, miniature PM motors may use high energy magnets made with neodymium; most are neodymium-iron-boron alloy. With their higher flux density, electric machines with high-energy PMs are at least competitive with all optimally designed singly-fed synchronous and induction electric machines. Miniature motors resemble the structure in the illustration, except that they have at least three rotor poles (to ensure starting, regardless of rotor position) and their outer housing is a steel tube that magnetically links the exteriors of the curved field magnets. === Electronic commutator (EC) === ==== Brushless DC ==== Some of the problems of the brushed DC motor are eliminated in the BLDC design. In this motor, the mechanical "rotating switch" or commutator is replaced by an external electronic switch synchronised to the rotor's position. BLDC motors are typically 85%+ efficient, reaching up to 96.5%, while brushed DC motors are typically 75–80% efficient. The BLDC motor's characteristic trapezoidal counter-electromotive force (CEMF) waveform is derived partly from the stator windings being evenly distributed, and partly from the placement of the rotor's permanent magnets. Also known as electronically commutated DC or inside-out DC motors, the stator windings of trapezoidal BLDC motors can be single-phase, two-phase or three-phase and use Hall effect sensors mounted on their windings for rotor position sensing and low cost closed-loop commutator control. BLDC motors are commonly used where precise speed control is necessary, as in computer disk drives or video cassette recorders. The spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products, such as fans, laser printers and photocopiers. They have several advantages over conventional motors: They are more efficient than AC fans using shaded-pole motors, running much cooler than the AC equivalents. This cool operation leads to much-improved life of the fan's bearings. Without a commutator, the life of a BLDC motor can be significantly longer compared to a brushed DC motor with a commutator. Commutation tends to cause electrical and RF noise; without a commutator or brushes, a BLDC motor may be used in electrically sensitive devices like audio equipment or computers. The same Hall effect sensors that provide the commutation can provide a convenient tachometer signal for closed-loop control (servo-controlled) applications. In fans, the tachometer signal can be used to derive a "fan OK" signal as well as provide running speed feedback. The motor can be synchronized to an internal or external clock, providing precise speed control. BLDC motors do not spark, making them better suited to environments with volatile chemicals and fuels. Sparking also generates ozone, which can accumulate in poorly ventilated buildings. BLDC motors are usually used in small equipment such as computers and are generally used in fans to remove heat. They make little noise, which is an advantage in equipment that is affected by vibrations. Modern BLDC motors range in power from a fraction of a watt to many kilowatts. Larger BLDC motors rated up to about 100 kW are used in electric vehicles. They also find use in electric model aircraft. ==== Switched reluctance motor ==== The switched reluctance motor (SRM) has no brushes or permanent magnets, and the rotor has no electric currents. Torque comes from a slight misalignment of poles on the rotor with poles on the stator. The rotor aligns itself with the magnetic field of the stator, while the stator field windings are sequentially energized to rotate the stator field. The magnetic flux created by the field windings follows the path of least magnetic sending the flux through rotor poles that are closest to the energized poles of the stator, thereby magnetizing those poles of the rotor and creating torque. As the rotor turns, different windings are energized, keeping the rotor turning. SRMs are used in some appliances and vehicles. === Universal AC/DC motor === A commutated, electrically excited, series or parallel wound motor is referred to as a universal motor because it can be designed to operate on either AC or DC power. A universal motor can operate well on AC because the current in both the field and the armature coils (and hence the resultant magnetic fields) synchronously reverse polarity, and hence the resulting mechanical force occurs in a constant direction of rotation. Operating at normal power line frequencies, universal motors are often used in sub-kilowatt applications. Universal motors formed the basis of the traditional railway traction motor in electric railways. In this application, using AC power on a motor designed to run on DC would experience efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron. They are now rarely used. An advantage is that AC power may be used on motors that specifically have high starting torque and compact design if high running speeds are used. By contrast, maintenance is higher and lifetimes are shortened. Such motors are used in devices that are not heavily used, and have high starting-torque demands. Multiple taps on the field coil provide (imprecise) stepped speed control. Household blenders that advertise many speeds typically combine a field coil with several taps and a diode that can be inserted in series with the motor (causing the motor to run on half-wave rectified AC). Universal motors also lend themselves to electronic speed control and, as such, are a choice for devices such as domestic washing machines. The motor can agitate the drum (both forwards and in reverse) by switching the field winding with respect to the armature. Whereas SCIMs cannot turn a shaft faster than allowed by the power line frequency, universal motors can run at much higher speeds. This makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high speed and light weight are desirable. They are also commonly used in portable power tools, such as drills, sanders, circular and jig saws, where the motor's characteristics work well. Many vacuum cleaner and weed trimmer motors exceed 10,000 rpm, while miniature grinders may exceed 30,000 rpm. == Externally commutated AC machine == AC induction and synchronous motors are optimized for operation on single-phase or polyphase sinusoidal or quasi-sinusoidal waveform power such as supplied for fixed-speed applications by the AC power grid or for variable-speed application from variable-frequency drive (VFD) controllers. === Induction motor === An induction motor is an asynchronous AC motor where power is transferred to the rotor by electromagnetic induction, much like transformer action. An induction motor resembles a rotating transformer, because the stator (stationary part) is essentially the primary side of the transformer and the rotor (rotating part) is the secondary side. Polyphase induction motors are widely used in industry. ==== Cage and wound rotor ==== Induction motors may be divided into Squirrel Cage Induction Motors (SCIM) and Wound Rotor Induction Motors (WRIM). SCIMs have a heavy winding made up of solid bars, usually aluminum or copper, electrically connected by rings at the ends of the rotor. The bars and rings as a whole are much like an animal's rotating exercise cage. Currents induced into this winding provide the rotor magnetic field. The shape of the rotor bars determines the speed-torque characteristics. At low speeds, the current induced in the squirrel cage is nearly at line frequency and tends to stay in the outer parts of the cage. As the motor accelerates, the slip frequency becomes lower, and more current reaches the interior. By shaping the bars to change the resistance of the winding portions in the interior and outer parts of the cage, a variable resistance is effectively inserted in the rotor circuit. However, most such motors employ uniform bars. In a WRIM, the rotor winding is made of many turns of insulated wire and is connected to slip rings on the motor shaft. An external resistor or other control device can be connected in the rotor circuit. Resistors allow control of the motor speed, although dissipating significant power. A converter can be fed from the rotor circuit and return the slip-frequency power that would otherwise be wasted into the power system through an inverter or separate motor-generator. WRIMs are used primarily to start a high inertia load or a load that requires high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low supply current from zero speed to full speed. Motor speed can be changed because the motor's torque curve is effectively modified by the amount of resistance connected to the rotor circuit. Increasing resistance lowers the speed of maximum torque. If the resistance is increased beyond the point where the maximum torque occurs at zero speed, the torque is further reduced. When used with a load that has a torque curve that increases with speed, the motor operates at the speed where the torque developed by the motor is equal to the load torque. Reducing the load causes the motor to speed up, while increasing the load causes the motor to slow down until the load and motor torque are again equal. Operated in this manner, the slip losses are dissipated in the secondary resistors and can be significant. The speed regulation and net efficiency is poor. ==== Torque motor ==== A torque motor can operate indefinitely while stalled, that is, with the rotor blocked from turning, without incurring damage. In this mode of operation, the motor applies a steady torque to the load. A common application is the supply- and take-up reel motors in a tape drive. In this application, driven by a low voltage, the characteristics of these motors apply a steady light tension to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage (delivering a higher torque), torque motors can achieve fast-forward and rewind operation without requiring additional mechanics such as gears or clutches. In the computer gaming world, torque motors are used in force feedback steering wheels. Another common application is to control the throttle of an internal combustion engine with an electronic governor. The motor works against a return spring to move the throttle in accord with the governor output. The latter monitors engine speed by counting electrical pulses from the ignition system or from a magnetic pickup and depending on the speed, makes small adjustments to the amount of current. If the engine slows down relative to the desired speed, the current increases, producing more torque, pulling against the return spring and opening the throttle. Should the engine run too fast, the governor reduces the current, allowing the return spring to pull back and reduce the throttle. === Synchronous motor === A synchronous electric motor is an AC motor. It includes a rotor spinning with coils passing magnets at the same frequency as the AC and produces a magnetic field to drive it. It has zero slip under typical operating conditions. By contrast induction motors must slip to produce torque. One type of synchronous motor is like an induction motor except that the rotor is excited by a DC field. Slip rings and brushes conduct current to the rotor. The rotor poles connect to each other and move at the same speed. Another type, for low load torque, has flats ground onto a conventional squirrel-cage rotor to create discrete poles. Yet another, as made by Hammond for its pre-World War II clocks, and in older Hammond organs, has no rotor windings and discrete poles. It is not self-starting. The clock requires manual starting by a small knob on the back, while the older Hammond organs had an auxiliary starting motor connected by a spring-loaded manually operated switch. Hysteresis synchronous motors typically are (essentially) two-phase motors with a phase-shifting capacitor for one phase. They start like induction motors, but when slip rate decreases sufficiently, the rotor (a smooth cylinder) becomes temporarily magnetized. Its distributed poles make it act like a permanent magnet synchronous motor. The rotor material, like that of a common nail, stays magnetized, but can be demagnetized with little difficulty. Once running, the rotor poles stay in place; they do not drift. Low-power synchronous timing motors (such as those for traditional electric clocks) may have multi-pole permanent magnet external cup rotors, and use shading coils to provide starting torque. Telechron clock motors have shaded poles for starting torque, and a two-spoke ring rotor that performs like a discrete two-pole rotor. === Doubly-fed electric machine === Doubly fed electric motors have two independent multiphase winding sets, which contribute active (i.e., working) power to the energy conversion process, with at least one of the winding sets electronically controlled for variable speed operation. Two independent multiphase winding sets (i.e., dual armature) are the maximum provided in a single package without topology duplication. Doubly-fed electric motors have an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation. This is twice the constant torque speed range as singly-fed electric machines, which have only one active winding set. A doubly-fed motor allows for a smaller electronic converter but the cost of the rotor winding and slip rings may offset the saving in the power electronics components. Difficulties affect controlling speed near synchronous speed limit applications. == Advanced types == === Rotary === ==== Ironless or coreless rotor motor ==== The coreless or ironless DC motor is a specialized permanent magnet DC motor. Optimized for rapid acceleration, the rotor is constructed without an iron core. The rotor can take the form of a winding-filled cylinder, or a self-supporting structure comprising only wire and bonding material. The rotor can fit inside the stator magnets; a magnetically soft stationary cylinder inside the rotor provides a return path for the stator magnetic flux. A second arrangement has the rotor winding basket surrounding the stator magnets. In that design, the rotor fits inside a magnetically soft cylinder that can serve as the motor housing, and provides a return path for the flux. Because the rotor is much lower mass than a conventional rotor, it can accelerate much more rapidly, often achieving a mechanical time constant under one millisecond. This is especially true if the windings use aluminum rather than (heavier) copper. The rotor has no metal mass to act as a heat sink; even small motors must be cooled. Overheating can be an issue for these designs. The vibrating alert of cellular phones can be generated by cylindrical permanent-magnet motors, or disc-shaped types that have a thin multipolar disc field magnet, and an intentionally unbalanced molded-plastic rotor structure with two bonded coreless coils. Metal brushes and a flat commutator switch power to the rotor coils. Related limited-travel actuators have no core and a bonded coil placed between the poles of high-flux thin permanent magnets. These are the fast head positioners for rigid-disk ("hard disk") drives. Although the contemporary design differs considerably from that of loudspeakers, it is still loosely (and incorrectly) referred to as a "voice coil" structure, because some earlier rigid-disk-drive heads moved in straight lines, and had a drive structure much like that of a loudspeaker. ==== Pancake or axial rotor motor ==== The printed armature or pancake motor has windings shaped as a disc running between arrays of high-flux magnets. The magnets are arranged in a circle facing the rotor spaced to form an axial air gap. This design is commonly known as the pancake motor because of its flat profile. The armature (originally formed on a printed circuit board) is made from punched copper sheets that are laminated together using advanced composites to form a thin, rigid disc. The armature does not have a separate ring commutator. The brushes move directly on the armature surface making the whole design compact. An alternative design is to use wound copper wire laid flat with a central conventional commutator, in a flower and petal shape. The windings are typically stabilized with electrical epoxy potting systems. These are filled epoxies that have moderate, mixed viscosity and a long gel time. They are highlighted by low shrinkage and low exotherm, and are typically UL 1446 recognized as a potting compound insulated with 180 °C (356 °F), Class H rating. The unique advantage of ironless DC motors is the absence of cogging (torque variations caused by changing attraction between the iron and the magnets). Parasitic eddy currents cannot form in the rotor as it is totally ironless, although iron rotors are laminated. This can greatly improve efficiency, but variable-speed controllers must use a higher switching rate (>40 kHz) or DC because of decreased electromagnetic induction. These motors were invented to drive the capstan(s) of magnetic tape drives, where minimal time to reach operating speed and minimal stopping distance were critical. Pancake motors are widely used in high-performance servo-controlled systems, robotic systems, industrial automation and medical devices. Due to the variety of constructions now available, the technology is used in applications from high temperature military to low cost pump and basic servos. Another approach (Magnax) is to use a single stator sandwiched between two rotors. One such design has produced peak power of 15 kW/kg, sustained power around 7.5 kW/kg. This yokeless axial flux motor offers a shorter flux path, keeping the magnets further from the axis. The design allows zero winding overhang; 100 percent of the windings are active. This is enhanced with the use of rectangular-crosssection copper wire. The motors can be stacked to work in parallel. Instabilities are minimized by ensuring that the two rotor discs put equal and opposing forces onto the stator disc. The rotors are connected directly to one another via a shaft ring, cancelling out the magnetic forces. ==== Servomotor ==== A servomotor is a motor that is used within a position-control or speed-control feedback system. Servomotors are used in applications such as machine tools, pen plotters, and other process systems. Motors intended for use in a servomechanism must have predictable characteristics for speed, torque, and power. The speed/torque curve is important and is high ratio for a servomotor. Dynamic response characteristics such as winding inductance and rotor inertia are important; these factors limit performance. Large, powerful, but slow-responding servo loops may use conventional AC or DC motors and drive systems with position or speed feedback. As dynamic response requirements increase, more specialized motor designs such as coreless motors are used. AC motors' superior power density and acceleration characteristics tends to favor permanent magnet synchronous, BLDC, induction, and SRM drive approaches. A servo system differs from some stepper motor applications in that position feedback is continuous while the motor is running. A stepper system inherently operates open-loop—relying on the motor not to "miss steps" for short term accuracy—with any feedback such as a "home" switch or position encoder external to the motor system. ==== Stepper motor ==== Stepper motors are typically used to provide precise rotations. An internal rotor containing permanent magnets or a magnetically soft rotor with salient poles is controlled by a set of electronically switched external magnets. A stepper motor may also be thought of as a cross between a DC electric motor and a rotary solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, the stepper motor may not rotate continuously; instead, it moves in steps—starting and then stopping—advancing from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards, and it may change direction, stop, speed up or slow down at any time. Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions. Microstepping drivers can proportionally control the power to the field windings, allowing the rotors to position between cog points and rotate smoothly. Computer-controlled stepper motors are one of the most versatile positioning systems, particularly as part of a digital servo-controlled system. Stepper motors can be rotated to a specific angle in discrete steps with ease, and hence stepper motors are used for read/write head positioning in early disk drives, where the precision and speed they offered could correctly position the read/write head. As drive density increased, precision and speed limitations made them obsolete for hard drives—the precision limitation made them unusable, and the speed limitation made them uncompetitive—thus newer hard disk drives use voice coil-based head actuator systems. (The term "voice coil" in this connection is historic; it refers to the structure in a cone-type loudspeaker.) Stepper motors are often used in computer printers, optical scanners, and digital photocopiers to move the active element, the print head carriage (inkjet printers), and the platen or feed rollers. So-called quartz analog wristwatches contain the smallest commonplace stepping motors; they have one coil, draw little power, and have a permanent magnet rotor. The same kind of motor drives battery-powered quartz clocks. Some of these watches, such as chronographs, contain more than one stepper motor. Closely related in design to three-phase AC synchronous motors, stepper motors and SRMs are classified as variable reluctance motor type. === Linear === A linear motor is essentially any electric motor that has been "unrolled" so that, instead of producing torque (rotation), it produces a straight-line force along its length. Linear motors are most commonly induction motors or stepper motors. Linear motors are commonly found in roller-coasters where the rapid motion of the motorless railcar is controlled by the rail. They are also used in maglev trains, where the train "flies" over the ground. On a smaller scale, the 1978 era HP 7225A pen plotter used two linear stepper motors to move the pen along the X and Y axes. === Non-magnetic === ==== Electrostatic ==== An electrostatic motor is based on the attraction and repulsion of electric charge. Usually, electrostatic motors are the dual of conventional coil-based motors. They typically require a high-voltage power supply, although small motors employ lower voltages. Conventional electric motors instead employ magnetic attraction and repulsion, and require high current at low voltages. In the 1750s, the first electrostatic motors were developed by Benjamin Franklin and Andrew Gordon. Electrostatic motors find frequent use in micro-electro-mechanical systems (MEMS) where their drive voltages are below 100 volts, and where moving, charged plates are far easier to fabricate than coils and iron cores. The molecular machinery that runs living cells is often based on linear and rotary electrostatic motors. ==== Piezoelectric ==== A piezoelectric motor or piezo motor is a type of electric motor based upon the change in shape of a piezoelectric material when an electric field is applied. Piezoelectric motors make use of the converse piezoelectric effect whereby the material produces acoustic or ultrasonic vibrations to produce linear or rotary motion. In one mechanism, the elongation in a single plane is used to make a series of stretches and position holds, similar to the way a caterpillar moves. ==== Electric propulsion ==== An electrically powered spacecraft propulsion system uses electric motor technology to propel spacecraft in outer space. Most systems are based on electrically accelerating propellant to high speed, while some systems are based on electrodynamic tethers principles of propulsion to the magnetosphere. == Comparison by major categories == == Operating principles == === Force and torque === An electric motor converts electrical energy to mechanical energy through the force between two opposed magnetic fields. At least one of the two magnetic fields must be created by an electromagnet through the magnetic field caused by an electrical current. The force between a current I {\displaystyle I} in a conductor of length ℓ {\displaystyle \ell } perpendicular to a magnetic field B {\displaystyle \mathbf {B} } may be calculated using the Lorentz force law: F = I ℓ × B {\displaystyle \mathbf {F} =I\ell \times \mathbf {B} } Note: X denotes vector cross product. The most general approaches to calculating the forces in motors use tensor notation. === Power === Electric motor output power is given as P em = T ω = F v {\displaystyle P_{\text{em}}=T\omega =Fv} where: ω {\displaystyle \omega } : shaft angular speed, [radians per second] T {\displaystyle T} : torque, [Newton-meters] F {\displaystyle F} : force, [Newtons] v {\displaystyle v} : velocity, [meters per second]. In Imperial units a motor's mechanical power output is given by, P em = ω rpm T 5252 {\displaystyle P_{\text{em}}={\frac {\omega _{\text{rpm}}T}{5252}}} (horsepower) where: ω rpm {\displaystyle \omega _{\text{rpm}}} , shaft angular speed [rpm] T {\displaystyle T} : torque, [foot-pounds]. In an asynchronous or induction motor, the relationship between motor speed and air gap power is given by the following: P airgap = R r s I r 2 {\displaystyle P_{\text{airgap}}={\frac {R_{r}}{s}}I_{r}^{2}} , where Rr – rotor resistance Ir2 – square of current induced in the rotor s – motor slip; i.e., difference between synchronous speed and slip speed, which provides the relative movement needed for current induction in the rotor. === Back EMF === The movement of armature windings of a direct-current or universal motor through a magnetic field, induce a voltage in them. This voltage tends to oppose the motor supply voltage and so is called "back electromotive force (EMF)". The voltage is proportional to the running speed of the motor. The back EMF of the motor, plus the voltage drop across the winding internal resistance and brushes, must equal the voltage at the brushes. This provides the fundamental mechanism of speed regulation in a DC motor. If the mechanical load increases, the motor slows down; a lower back EMF results, and more current is drawn from the supply. This increased current provides the additional torque to balance the load. In AC machines, it is sometimes useful to consider a back EMF source within the machine; this is of particular concern for close speed regulation of induction motors on VFDs. === Losses === Motor losses are mainly due to resistive losses in windings, core losses and mechanical losses in bearings, and aerodynamic losses, particularly where cooling fans are present, also occur. Losses also occur in commutation, mechanical commutators spark; electronic commutators and also dissipate heat. === Efficiency === To calculate a motor's efficiency, the mechanical output power is divided by the electrical input power: η = P m P e {\displaystyle \eta ={\frac {P_{\text{m}}}{P_{\text{e}}}}} , where η {\displaystyle \eta } is energy conversion efficiency, P e {\displaystyle P_{\text{e}}} is electrical input power, and P m {\displaystyle P_{\text{m}}} is mechanical output power: P e = I V {\displaystyle P_{\text{e}}=IV} P m = T ω {\displaystyle P_{\text{m}}=T\omega } where V {\displaystyle V} is input voltage, I {\displaystyle I} is input current, T {\displaystyle T} is output torque, and ω {\displaystyle \omega } is output angular velocity. It is possible to derive analytically the point of maximum efficiency. It is typically at less than 1/2 the stall torque. Various national regulatory authorities have enacted legislation to encourage the manufacture and use of higher-efficiency motors. Electric motors have efficiencies ranging from around 15%-20% for shaded pole motors, up to 98% for permanent magnet motors, with efficiency also dependent on load. Peak efficiency is usually at 75% of the rated load. So (as an example) a 10 HP motor is most efficient when driving a load that requires 7.5 HP. Efficiency also depends on motor size; larger motors tend to be more efficient. Some motors can not operate continually for more than a specified period of time (e.g. for more than an hour per run) === Goodness factor === Eric Laithwaite proposed a metric to determine the 'goodness' of an electric motor: G = ω resistance × reluctance = ω μ σ A m A e l m l e {\displaystyle G={\frac {\omega }{{\text{resistance}}\times {\text{reluctance}}}}={\frac {\omega \mu \sigma A_{\text{m}}A_{\text{e}}}{l_{\text{m}}l_{\text{e}}}}} Where: G {\displaystyle G} is the goodness factor (factors above 1 are likely to be efficient) A m , A e {\displaystyle A_{\text{m}},A_{\text{e}}} are the cross sectional areas of the magnetic and electric circuit l m , l e {\displaystyle l_{\text{m}},l_{\text{e}}} are the lengths of the magnetic and electric circuits μ {\displaystyle \mu } is the permeability of the core ω {\displaystyle \omega } is the angular frequency the motor is driven at From this, he showed that the most efficient motors are likely to have relatively large magnetic poles. However, the equation only directly relates to non PM motors. == Performance parameters == === Torque === Electromagnetic motors derive torque from the vector product of the interacting fields. Calculating torque requires knowledge of the fields in the air gap. Once these have been established, the torque is the integral of all the force vectors multiplied by the vector's radius. The current flowing in the winding produces the fields. For a motor using a magnetic material the field is not proportional to the current. A figure relating the current to the torque can inform motor selection. The maximum torque for a motor depends on the maximum current, absent thermal considerations. When optimally designed within a given core saturation constraint and for a given active current (i.e., torque current), voltage, pole-pair number, excitation frequency (i.e., synchronous speed), and air-gap flux density, all categories of electric motors/generators exhibit virtually the same maximum continuous shaft torque (i.e., operating torque) within a given air-gap area with winding slots and back-iron depth, which determines the physical size of electromagnetic core. Some applications require bursts of torque beyond the maximum, such as bursts to accelerate an electric vehicle from standstill. Always limited by magnetic core saturation or safe operating temperature rise and voltage, the capacity for torque bursts beyond the maximum differs significantly across motor/generator types. Electric machines without a transformer circuit topology, such as that of WRSMs or PMSMs, cannot provide torque bursts without saturating the magnetic core. At that point, additional current cannot increase torque. Furthermore, the permanent magnet assembly of PMSMs can be irreparably damaged. Electric machines with a transformer circuit topology, such as induction machines, induction doubly-fed electric machines, and induction or synchronous wound-rotor doubly-fed (WRDF) machines, permit torque bursts because the EMF-induced active current on either side of the transformer oppose each other and thus contribute nothing to the transformer coupled magnetic core flux density, avoiding core saturation. Electric machines that rely on induction or asynchronous principles short-circuit one port of the transformer circuit and as a result, the reactive impedance of the transformer circuit becomes dominant as slip increases, which limits the magnitude of active (i.e., real) current. Torque bursts two to three times higher than the maximum design torque are realizable. The brushless wound-rotor synchronous doubly-fed (BWRSDF) machine is the only electric machine with a truly dual ported transformer circuit topology (i.e., both ports independently excited with no short-circuited port). The dual ported transformer circuit topology is known to be unstable and requires a multiphase slip-ring-brush assembly to propagate limited power to the rotor winding set. If a precision means were available to instantaneously control torque angle and slip for synchronous operation during operation while simultaneously providing brushless power to the rotor winding set, the active current of the BWRSDF machine would be independent of the reactive impedance of the transformer circuit and bursts of torque significantly higher than the maximum operating torque and far beyond the practical capability of any other type of electric machine would be realizable. Torque bursts greater than eight times operating torque have been calculated. === Continuous torque density === The continuous torque density of conventional electric machines is determined by the size of the air-gap area and the back-iron depth, which are determined by the power rating of the armature winding set, the speed of the machine, and the achievable air-gap flux density before core saturation. Despite the high coercivity of neodymium or samarium-cobalt permanent magnets, continuous torque density is virtually the same amongst electric machines with optimally designed armature winding sets. Continuous torque density relates to method of cooling and permissible operation period before destruction by overheating of windings or permanent magnet damage. Other sources state that various e-machine topologies have differing torque density. One source shows the following: where—specific torque density is normalized to 1.0 for the surface permanent magnet (SPM)—brushless ac, 180° current conduction. Torque density is approximately four times greater for liquid cooled motors, compared to those which are air cooled. A source comparing direct current, induction motors (IM), PMSM and SRM showed: Another source notes that PMSM up to 1 MW have considerably higher torque density than induction machines. === Continuous power density === The continuous power density is determined by the product of the continuous torque density and the constant torque speed range. Electric motors can achieve densities of up to 20 kW/kg, meaning 20 kilowatts of output power per kilogram. == Acoustic noise and vibrations == Acoustic noise and vibrations are usually classified in three sources: mechanical sources (e.g. due to bearings) aerodynamic sources (e.g. due to shaft-mounted fans) magnetic sources (e.g. due to magnetic forces such as Maxwell and magnetostriction forces acting on stator and rotor structures) The latter source, which can be responsible for the "whining noise" of electric motors, is called electromagnetically induced acoustic noise. == Standards == The following are major design, manufacturing, and testing standards covering electric motors: American Petroleum Institute: API 541 Form-Wound Squirrel Cage Induction Motors – 375 kW (500 Horsepower) and Larger American Petroleum Institute: API 546 Brushless Synchronous Machines – 500 kVA and Larger American Petroleum Institute: API 547 General-purpose Form-Wound Squirrel Cage Induction Motors – 250 Hp and Larger Institute of Electrical and Electronics Engineers: IEEE Std 112 Standard Test Procedure for Polyphase Induction Motors and Generators Institute of Electrical and Electronics Engineers: IEEE Std 115 Guide for Test Procedures for Synchronous Machines Institute of Electrical and Electronics Engineers: IEEE Std 841 Standard for Petroleum and Chemical Industry – Premium Efficiency Severe Duty Totally Enclosed Fan-Cooled (TEFC) Squirrel Cage Induction Motors – Up to and Including 370 kW (500 Hp) International Electrotechnical Commission: IEC 60034 Rotating Electrical Machines International Electrotechnical Commission: IEC 60072 Dimensions and output series for rotating electrical machines National Electrical Manufacturers Association: MG-1 Motors and Generators Underwriters Laboratories: UL 1004 – Standard for Electric Motors Indian Standard: IS:12615-2018 – Line Operated Three Phase a.c. Motors (IE CODE) "Efficiency Classes and Performance Specification" (Third Revision) == See also == Compensation winding Electric generator Electric vehicle motor Goodness factor Motor capacitor Motor controller Regenerative brake Traction motor == Notes == == References == == Bibliography == == Further reading == == External links == SparkMuseum: Early Electric Motors The Invention of the Electric Motor 1800 to 1893, hosted by Karlsrushe Institute of Technology's Martin Doppelbauer MAS.865 2018 How to Make Something that Makes (almost) Anything, slow motion gifs and oscillograms for many kinds of motors.

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be brushed or brushless, single-phase, two-phase, or three-phase, axial or radial flux, and may be air-cooled or liquid-cooled. Standardized motors provide power for industrial use. The largest are used for ship propulsion, pipeline compression and pumped-storage applications, with output exceeding 100 megawatts. Applications include industrial fans, blowers and pumps, machine tools, household appliances, power tools, vehicles, and disk drives. Small motors may be found in electric watches. In certain applications, such as in regenerative braking with traction motors, electric motors can be used in reverse as generators to recover energy that might otherwise be lost as heat and friction. Electric motors produce linear or rotary force (torque) intended to propel some external mechanism. This makes them a type of actuator. They are generally designed for continuous rotation, or for linear movement over a significant distance compared to its size. Solenoids also convert electrical power to mechanical motion, but over only a limited distance.

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censorship

Zensur (wiktionary)

IPA(key): /t͡sɛnˈzuːɐ̯/ Zensur f (genitive Zensur, plural Zensuren) censorship (education) mark, grade “Zensur” in Digitales Wörterbuch der deutschen Sprache “Zensur” in Uni Leipzig: Wortschatz-Lexikon “Zensur” in Duden online IPA(key): [t͡sænˈzuːɐ̯] Zensur f (plural Zensuren) school report censorship

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censorship

censorship (wiktionary)

From censor +‎ -ship. (Received Pronunciation) IPA(key): /ˈsɛnsəʃɪp/ (General American) IPA(key): /ˈsɛnsɚʃɪp/ Hyphenation: cen‧sor‧ship censorship (countable and uncountable, plural censorships) The use of state or group power to control freedom of expression or press, such as passing laws to prevent media from being published or propagated. (historical) The role of the censor (magistrate) in Ancient Rome. bleep censor censor censorware bowdlerisation media democracy moral panic sensorchip, sphericons

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censorship

Censorship (wikipedia)

Censorship is the suppression of speech, public communication, or other information. This may be done on the basis that such material is considered objectionable, harmful, sensitive, or "inconvenient". Censorship can be conducted by governments, private institutions, and other controlling bodies. Governments sometimes engage in censorship. Other groups or institutions may propose and petition for censorship. When an individual such as an author or other creator engages in censorship of their own works or speech, it is referred to as self-censorship. General censorship occurs in a variety of different media, including speech, books, music, films, and other arts, the press, radio, television, and the Internet for a variety of claimed reasons including national security, to control obscenity, pornography, and hate speech, to protect children or other vulnerable groups, to promote or restrict political or religious views, and to prevent slander and libel. Specific rules and regulations regarding censorship vary between legal jurisdictions and/or private organizations. == History == In 399 BC, Greek philosopher, Socrates, while defying attempts by the Athenian state to censor his philosophical teachings, was accused of collateral charges related to the corruption of Athenian youth and sentenced to death by drinking a poison, hemlock. The details of Socrates's conviction are recorded by Plato as follows. In 399 BC, Socrates went on trial and was subsequently found guilty of both corrupting the minds of the youth of Athens and of impiety (asebeia, "not believing in the gods of the state"), and as a punishment sentenced to death, caused by the drinking of a mixture containing hemlock. Socrates' student, Plato, is said to have advocated censorship in his essay on The Republic, which opposed the existence of democracy. In contrast to Plato, Greek playwright Euripides (480–406 BC) defended the true liberty of freeborn men, including the right to speak freely. In 1766, Sweden became the first country to abolish censorship by law. == Rationale and criticism == Censorship has been criticized throughout history for being unfair and hindering progress. In a 1997 essay on Internet censorship, social commentator Michael Landier explains that censorship is counterproductive as it prevents the censored topic from being discussed. Landier expands his argument by claiming that those who impose censorship must consider what they censor to be true, as individuals believing themselves to be correct would welcome the opportunity to disprove those with opposing views. Censorship is often used to impose moral values on society, as in the censorship of material considered obscene. English novelist E. M. Forster was a staunch opponent of censoring material on the grounds that it was obscene or immoral, raising the issue of moral subjectivity and the constant changing of moral values. When the 1928 novel Lady Chatterley's Lover was put on trial in 1960, Forster wrote: Lady Chatterley's Lover is a literary work of importance...I do not think that it could be held obscene, but am in a difficulty here, for the reason that I have never been able to follow the legal definition of obscenity. The law tells me that obscenity may deprave and corrupt, but as far as I know, it offers no definition of depravity or corruption. Proponents have sought to justify it using different rationales for various types of information censored: Moral censorship is the removal of materials that are obscene or otherwise considered morally questionable. Pornography, for example, is often censored under this rationale, especially child pornography, which is illegal and censored in most jurisdictions in the world. Military censorship is the process of keeping military intelligence and tactics confidential and away from the enemy. This is used to counter espionage. Political censorship occurs when governments hold back information from their citizens. This is often done to exert control over the populace and prevent free expression that might foment rebellion. Religious censorship is the means by which any material considered objectionable by a certain religion is removed. This often involves a dominant religion forcing limitations on less prevalent ones. Alternatively, one religion may shun the works of another when they believe the content is not appropriate for their religion. Corporate censorship is the process by which editors in corporate media outlets intervene to disrupt the publishing of information that portrays their business or business partners in a negative light, or intervene to prevent alternate offers from reaching public exposure. == Types == === Political === === State secrets and prevention of attention === In wartime, explicit censorship is carried out with the intent of preventing the release of information that might be useful to an enemy. Typically it involves keeping times or locations secret, or delaying the release of information (e.g., an operational objective) until it is of no possible use to enemy forces. The moral issues here are often seen as somewhat different, as the proponents of this form of censorship argue that the release of tactical information usually presents a greater risk of casualties among one's own forces and could possibly lead to loss of the overall conflict. During World War I letters written by British soldiers would have to go through censorship. This consisted of officers going through letters with a black marker and crossing out anything which might compromise operational secrecy before the letter was sent. The World War II catchphrase "Loose lips sink ships" was used as a common justification to exercise official wartime censorship and encourage individual restraint when sharing potentially sensitive information. An example of "sanitization" policies comes from the USSR under Joseph Stalin, where publicly used photographs were often altered to remove people whom Stalin had condemned to execution. Though past photographs may have been remembered or kept, this deliberate and systematic alteration to all of history in the public mind is seen as one of the central themes of Stalinism and totalitarianism. Censorship is occasionally carried out to aid authorities or to protect an individual, as with some kidnappings when attention and media coverage of the victim can sometimes be seen as unhelpful. === Religion === Censorship by religion is a form of censorship where freedom of expression is controlled or limited using religious authority or on the basis of the teachings of the religion. This form of censorship has a long history and is practiced in many societies and by many religions. Examples include the Galileo affair, Edict of Compiègne, the Index Librorum Prohibitorum (list of prohibited books) and the condemnation of Salman Rushdie's novel The Satanic Verses by Iranian leader Ayatollah Ruhollah Khomeini. Images of the Islamic figure Muhammad are also regularly censored. In some secular countries, this is sometimes done to prevent hurting religious sentiments. === Educational sources === The content of school textbooks is often an issue of debate, since their target audiences are young people. The term whitewashing is commonly used to refer to revisionism aimed at glossing over difficult or questionable historical events, or a biased presentation thereof. The reporting of military atrocities in history is extremely controversial, as in the case of the Holocaust (or Holocaust denial), Bombing of Dresden, the Nanking Massacre as found with Japanese history textbook controversies, the Armenian genocide, the Tiananmen Square protests of 1989, and the Winter Soldier Investigation of the Vietnam War. In the context of secondary school education, the way facts and history are presented greatly influences the interpretation of contemporary thought, opinion and socialization. One argument for censoring the type of information disseminated is based on the inappropriate quality of such material for the younger public. The use of the "inappropriate" distinction is in itself controversial, as it changed heavily. A Ballantine Books version of the book Fahrenheit 451 which is the version used by most school classes contained approximately 75 separate edits, omissions, and changes from the original Bradbury manuscript. In February 2006, a National Geographic cover was censored by the Nashravaran Journalistic Institute. The offending cover was about the subject of love and a picture of an embracing couple was hidden beneath a white sticker. === Economic induced censorship === Economic induced censorship is a type of censorship enacted by economic markets to favor, and disregard, types of information. Economic induced censorship, is also caused, by market forces which privatize and establish commodification of certain information that is not accessible by the general public, primarily because of the cost associated with commodified information such as academic journals, industry reports and pay to use repositories. The concept was illustrated as a censorship pyramid that was conceptualized by primarily Julian Assange, along with Andy Müller-Maguhn, Jacob Appelbaum and Jérémie Zimmermann, in the Cypherpunks (book). === Self-censorship === Self-censorship is the act of censoring or classifying one's own discourse. This is done out of fear of, or deference to, the sensibilities or preferences (actual or perceived) of others and without overt pressure from any specific party or institution of authority. Self-censorship is often practiced by film producers, film directors, publishers, news anchors, journalists, musicians, and other kinds of authors including individuals who use social media. According to a Pew Research Center and the Columbia Journalism Review survey, "About one-quarter of the local and national journalists say they have purposely avoided newsworthy stories, while nearly as many acknowledge they have softened the tone of stories to benefit the interests of their news organizations. Fully four-in-ten (41%) admit they have engaged in either or both of these practices." Threats to media freedom have shown a significant increase in Europe in recent years, according to a study published in April 2017 by the Council of Europe. This results in a fear of physical or psychological violence, and the ultimate result is self-censorship by journalists. === Copy, picture, and writer approval === Copy approval is the right to read and amend an article, usually an interview, before publication. Many publications refuse to give copy approval but it is increasingly becoming common practice when dealing with publicity anxious celebrities. Picture approval is the right given to an individual to choose which photos will be published and which will not. Robert Redford is well known for insisting upon picture approval. Writer approval is when writers are chosen based on whether they will write flattering articles or not. Hollywood publicist Pat Kingsley is known for banning certain writers who wrote undesirably about one of her clients from interviewing any of her other clients. === Reverse censorship === Flooding the public, often through online social networks, with false or misleading information is sometimes called "reverse censorship". American legal scholar Tim Wu has explained that this type of information control, sometimes by state actors, can "distort or drown out disfavored speech through the creation and dissemination of fake news, the payment of fake commentators, and the deployment of propaganda robots." === Soft censorship === Soft, or indirect, censorship is the practice of influencing news coverage by applying financial pressure on media companies that are deemed critical of a government or its policies and rewarding media outlets and individual journalists who are seen as friendly to the government. == By media == === Books === Book censorship can be enacted at the national or sub-national level, and can carry legal penalties for their infraction. Books may also be challenged at a local, community level. As a result, books can be removed from schools or libraries, although these bans do not typically extend outside of that area. === Films === Aside from the usual justifications of pornography and obscenity, some films are censored due to changing racial attitudes or political correctness in order to avoid ethnic stereotyping and/or ethnic offense despite its historical or artistic value. One example is the still withdrawn "Censored Eleven" series of animated cartoons, which may have been innocent then, but are "incorrect" now. Film censorship is carried out by various countries. Film censorship is achieved by censoring the producer or restricting a state citizen. For example, in China the film industry censors LGBT-related films. Filmmakers must resort to finding funds from international investors such as the "Ford Foundations" and or produce through an independent film company. === Music === Music censorship has been implemented by states, religions, educational systems, families, retailers and lobbying groups – and in most cases they violate international conventions of human rights. === Maps === Censorship of maps is often employed for military purposes. For example, the technique was used in former East Germany, especially for the areas near the border to West Germany in order to make attempts of defection more difficult. Censorship of maps is also applied by Google Maps, where certain areas are grayed out or blacked or areas are purposely left outdated with old imagery. === Art === Art is loved and feared because of its evocative power. Destroying or oppressing art can potentially justify its meaning even more. British photographer and visual artist Graham Ovenden's photos and paintings were ordered to be destroyed by a London's magistrate court in 2015 for being "indecent" and their copies had been removed from the online Tate gallery. A 1980 Israeli law forbade banned artwork composed of the four colours of the Palestinian flag, and Palestinians were arrested for displaying such artwork or even for carrying sliced melons with the same pattern. Moath al-Alwi is a Guantanamo Bay prisoner who creates model ships as an expression of art. Alwi does so with the few tools he has at his disposal such as dental floss and shampoo bottles, and he is also allowed to use a small pair of scissors with rounded edges. A few of Alwi's pieces are on display at John Jay College of Criminal Justice in New York. There are also other artworks on display at the College that were created by other inmates. The artwork that is being displayed might be the only way for some of the inmates to communicate with the outside. Recently things have changed though. The military has come up with a new policy that will not allow the artwork at Guantanamo Bay Military Prison to leave the prison. The artwork created by Alwi and other prisoners is now government property and can be destroyed or disposed of in whatever way the government choose, making it no longer the artist's property. Around 300 artists in Cuba are fighting for their artistic freedom due to new censorship rules Cuba's government has in place for artists. In December 2018, following the introduction of new rules that would ban music performances and artwork not authorized by the state, performance artist Tania Bruguera was detained upon arriving to Havana and released after four days. An example of extreme state censorship was the Nazis' requirements of using art as propaganda. Art was only allowed to be used as a political instrument to control people and failure to act in accordance with the censors was punishable by law, even fatal. The Degenerate Art Exhibition was a historical instance of this, the goal of which was to advertise Nazi values and slander others. === Internet === Internet censorship is control or suppression of the publishing or accessing of information on the Internet. It may be carried out by governments or by private organizations either at the behest of the government or on their own initiative. Individuals and organizations may engage in self-censorship on their own or due to intimidation and fear. The issues associated with Internet censorship are similar to those for offline censorship of more traditional media. One difference is that national borders are more permeable online: residents of a country that bans certain information can find it on websites hosted outside the country. Thus censors must work to prevent access to information even though they lack physical or legal control over the websites themselves. This in turn requires the use of technical censorship methods that are unique to the Internet, such as site blocking and content filtering. Furthermore, the Domain Name System (DNS) a critical component of the Internet is dominated by centralized and few entities. The most widely used DNS root is administered by the Internet Corporation for Assigned Names and Numbers (ICANN). As an administrator they have rights to shut down and seize domain names when they deem necessary to do so and at most times the direction is from governments. This has been the case with Wikileaks shutdowns and name seizure events such as the ones executed by the National Intellectual Property Rights Coordination Center (IPR Center) managed by the Homeland Security Investigations (HSI). This makes it easy for internet censorship by authorities as they have control over what should or should not be on the Internet. Some activists and researchers have started opting for alternative DNS roots, though the Internet Architecture Board (IAB) does not support these DNS root providers. Unless the censor has total control over all Internet-connected computers, such as in North Korea or Cuba, total censorship of information is very difficult or impossible to achieve due to the underlying distributed technology of the Internet. Pseudonymity and data havens (such as Freenet) protect free speech using technologies that guarantee material cannot be removed and prevents the identification of authors. Technologically savvy users can often find ways to access blocked content. Nevertheless, blocking remains an effective means of limiting access to sensitive information for most users when censors, such as those in China, are able to devote significant resources to building and maintaining a comprehensive censorship system. Views about the feasibility and effectiveness of Internet censorship have evolved in parallel with the development of the Internet and censorship technologies: A 1993 Time magazine article quotes computer scientist John Gillmore, one of the founders of the Electronic Frontier Foundation, as saying "The Net interprets censorship as damage and routes around it." In November 2007, "Father of the Internet" Vint Cerf stated that he sees government control of the Internet failing because the Web is almost entirely privately owned. A report of research conducted in 2007 and published in 2009 by the Beckman Center for Internet & Society at Harvard University stated that: "We are confident that the [censorship circumvention] tool developers will for the most part keep ahead of the governments' blocking efforts", but also that "...we believe that less than two percent of all filtered Internet users use circumvention tools". In contrast, a 2011 report by researchers at the Oxford Internet Institute published by UNESCO concludes "... the control of information on the Internet and Web is certainly feasible, and technological advances do not therefore guarantee greater freedom of speech." A BBC World Service poll of 27,973 adults in 26 countries, including 14,306 Internet users, was conducted between 30 November 2009 and 7 February 2010. The head of the polling organization felt, overall, that the poll showed that: Despite worries about privacy and fraud, people around the world see access to the internet as their fundamental right. They think the web is a force for good, and most don't want governments to regulate it. The poll found that nearly four in five (78%) Internet users felt that the Internet had brought them greater freedom, that most Internet users (53%) felt that "the internet should never be regulated by any level of government anywhere", and almost four in five Internet users and non-users around the world felt that access to the Internet was a fundamental right (50% strongly agreed, 29% somewhat agreed, 9% somewhat disagreed, 6% strongly disagreed, and 6% gave no opinion). ==== Social media ==== The rising use of social media in many nations has led to the emergence of citizens organizing protests through social media, sometimes called "Twitter Revolutions". The most notable of these social media-led protests were the Arab Spring uprisings, starting in 2010. In response to the use of social media in these protests, the Tunisian government began a hack of Tunisian citizens' Facebook accounts, and reports arose of accounts being deleted. Automated systems can be used to censor social media posts, and therefore limit what citizens can say online. This most notably occurs in China, where social media posts are automatically censored depending on content. In 2013, Harvard political science professor Gary King led a study to determine what caused social media posts to be censored and found that posts mentioning the government were not more or less likely to be deleted if they were supportive or critical of the government. Posts mentioning collective action were more likely to be deleted than those that had not mentioned collective action. Currently, social media censorship appears primarily as a way to restrict Internet users' ability to organize protests. For the Chinese government, seeing citizens unhappy with local governance is beneficial as state and national leaders can replace unpopular officials. King and his researchers were able to predict when certain officials would be removed based on the number of unfavorable social media posts. Research has proved that criticism is tolerable on social media sites, therefore it is not censored unless it has a higher chance of collective action. It is not important whether the criticism is supportive or unsupportive of the states' leaders, the main priority of censoring certain social media posts is to make sure that no big actions are being made due to something that was said on the internet. Posts that challenge the Party's political leading role in the Chinese government are more likely to be censored due to the challenges it poses to the Chinese Communist Party. In December 2022 Elon Musk, owner and CEO of Twitter released internal documents from the social media microblogging site to journalists Matt Taibbi, Michael Shellenberger and Bari Weiss. The analysis of these files on Twitter, collectively called, the Twitter Files, explored the content moderation and visibility filtering carried out in collaboration with the Federal Bureau of Investigation on the Hunter Biden laptop controversy. On the platform TikTok, certain hashtags have been categorized by the platform's code and determines how viewers can or cannot interact with the content or hashtag specifically. Some shadowbanned tags include: #acab, #GayArab, #gej due to their referencing of certain social movements and LGBTQ identity. As TikTok guidelines are becoming more localized around the world, some experts believe that this could result in more censorship than before. === Video games === Since the early 1980s, advocates of video games have emphasized their use as an expressive medium, arguing for their protection under the laws governing freedom of speech and also as an educational tool. Detractors argue that video games are harmful and therefore should be subject to legislative oversight and restrictions. Many video games have certain elements removed or edited due to regional rating standards. For example, in the Japanese and PAL Versions of No More Heroes, blood splatter and gore is removed from the gameplay. Decapitation scenes are implied, but not shown. Scenes of missing body parts after having been cut off, are replaced with the same scene, but showing the body parts fully intact. == Impact of surveillance == Surveillance and censorship are different. Surveillance can be performed without censorship, but it is harder to engage in censorship without some form of surveillance. Even when surveillance does not lead directly to censorship, the widespread knowledge or belief that a person, their computer, or their use of the Internet is under surveillance can have a "chilling effect" and lead to self-censorship. == Implementation == The former Soviet Union maintained a particularly extensive program of state-imposed censorship. The main organ for official censorship in the Soviet Union was the Chief Agency for Protection of Military and State Secrets generally known as the Glavlit, its Russian acronym. The Glavlit handled censorship matters arising from domestic writings of just about any kind – even beer and vodka labels. Glavlit censorship personnel were present in every large Soviet publishing house or newspaper; the agency employed some 70,000 censors to review information before it was disseminated by publishing houses, editorial offices, and broadcasting studios. No mass medium escaped Glavlit's control. All press agencies and radio and television stations had Glavlit representatives on their editorial staffs. Sometimes, public knowledge of the existence of a specific document is subtly suppressed, a situation resembling censorship. The authorities taking such action will justify it by declaring the work to be "subversive" or "inconvenient". An example is Michel Foucault's 1978 text Sexual Morality and the Law (later republished as The Danger of Child Sexuality), originally published as La loi de la pudeur [literally, "the law of decency"]. This work defends the decriminalization of statutory rape and the abolition of age of consent laws. When a publisher comes under pressure to suppress a book, but has already entered into a contract with the author, they will sometimes effectively censor the book by deliberately ordering a small print run and making minimal, if any, attempts to publicize it. This practice became known in the early 2000s as privishing (private publishing). an OpenNet Initiative (ONI) classifications: == By country == Censorship for individual countries is measured by Freedom House (FH) Freedom of the Press report, Reporters Without Borders (RWB) Press freedom index and V-Dem government censorship effort index. Censorship aspects are measured by Freedom on the Net and OpenNet Initiative (ONI) classifications. Censorship by country collects information on censorship, internet censorship, press freedom, freedom of speech, and human rights by country and presents it in a sortable table, together with links to articles with more information. In addition to countries, the table includes information on former countries, disputed countries, political sub-units within countries, and regional organizations. === Australia === === Canada === Very little is formally censored in Canada, aside from "obscenity" (as defined in the landmark criminal case of R v Butler) which is generally limited to pornography and child pornography depicting and/or advocating non-consensual sex, sexual violence, degradation, or dehumanization, in particular that which causes harm (as in R v Labaye). Most films are simply subject to classification by the British Columbia Film Classification Office under the non-profit Crown corporation by the name of Consumer Protection BC, whose classifications are officially used by the provinces of British Columbia, Saskatchewan, Ontario, and Manitoba. === Cuba === Cuban media used to be operated under the supervision of the Communist Party's Department of Revolutionary Orientation, which "develops and coordinates propaganda strategies". Connection to the Internet is restricted and censored. === China === The People's Republic of China employs sophisticated censorship mechanisms, referred to as the Golden Shield Project, to monitor the internet. Popular search engines such as Baidu also remove politically sensitive search results. === Eastern Bloc === Strict censorship existed in the Eastern Bloc. Throughout the bloc, the various ministries of culture held a tight rein on their writers. Cultural products there reflected the propaganda needs of the state. Party-approved censors exercised strict control in the early years. In the Stalinist period, even the weather forecasts were changed if they suggested that the sun might not shine on May Day. Under Nicolae Ceauşescu in Romania, weather reports were doctored so that the temperatures were not seen to rise above or fall below the levels which dictated that work must stop. Possession and use of copying machines was tightly controlled in order to hinder the production and distribution of samizdat, illegal self-published books and magazines. Possession of even a single samizdat manuscript such as a book by Andrei Sinyavsky was a serious crime which might involve a visit from the KGB. Another outlet for works which did not find favor with the authorities was publishing abroad. === France === Amid declining car sales in 2020, France banned a television ad by a Dutch bike company, saying the ad "unfairly discredited the automobile industry". === India === The Constitution of India guarantees freedom of expression, but places certain restrictions on content, with a view towards maintaining communal and religious harmony, given the history of communal tension in the nation. According to the Information Technology Rules 2011, objectionable content includes anything that "threatens the unity, integrity, defence, security or sovereignty of India, friendly relations with foreign states or public order". Notably many pornographic websites are blocked in India. === Iran === === Iraq === Iraq under Baathist Saddam Hussein had much the same techniques of press censorship as did Romania under Nicolae Ceauşescu but with greater potential violence. === Japan === During the GHQ occupation of Japan after WW2, any criticism of the Allies' pre-war policies, the SCAP, the Far East Military Tribunal, the inquiries against the United States and every direct and indirect references to the role played by the Allied High Command in drafting Japan's new constitution or to censorship of publications, movies, newspapers and magazines was subject to massive censorship, purges, media blackout. In the four years (September 1945–November 1949) since the CCD was active, 200 million pieces of mail and 136 million telegrams were opened, and telephones were tapped 800,000 times. Since no criticism of the occupying forces for crimes such as the dropping of the atomic bomb, rape and robbery by US soldiers was allowed, a strict check was carried out. Those who got caught were put on a blacklist called the watchlist, and the persons and the organizations to which they belonged were investigated in detail, which made it easier to dismiss or arrest the "disturbing molecule". === Malaysia === Under subsection 48(3) and (4) of the Penang Islamic Religious Administration Enactment 2004, non-Muslims in Malaysia are penalized for using the following words, or to write or publish them, in any form, version or translation in any language or for use in any publicity material in any medium: "Allah", "Firman Allah", "Ulama", "Hadith", "Ibadah", "Kaabah", "Qadhi'", "Illahi", "Wahyu", "Mubaligh", "Syariah", "Qiblat", "Haji", "Mufti", "Rasul", "Iman", "Dakwah", "Wali", "Fatwa", "Imam", "Nabi", "Sheikh", "Khutbah", "Tabligh", "Akhirat", "Azan", "Al Quran", "As Sunnah", "Auliya'", "Karamah", "False Moon God", "Syahadah", "Baitullah", "Musolla", "Zakat Fitrah", "Hajjah", "Taqwa" and "Soleh". === North Korea === === Russia === On 4 March 2022, Russian President Vladimir Putin signed into law a bill introducing prison sentences of up to 15 years for those who publish "knowingly false information" about the Russian military and its operations, leading to some media outlets in Russia to stop reporting on Ukraine or shutting their media outlet. Although the 1993 Russian Constitution has an article expressly prohibiting censorship, the Russian censorship apparatus Roskomnadzor ordered the country's media to only use information from Russian state sources or face fines and blocks. As of December 2022, more than 4,000 people were prosecuted under "fake news" laws in connection with the war in Ukraine. Novaya Gazeta's editor-in-chief Dmitry Muratov was awarded the 2021 Nobel Peace Prize for his "efforts to safeguard freedom of expression". In March 2022, Novaya Gazeta suspended its print activities after receiving a second warning from Roskomnadzor. === Serbia === According to Christian Mihr, executive director of Reporters Without Borders, "censorship in Serbia is neither direct nor transparent, but is easy to prove." According to Mihr there are numerous examples of censorship and self-censorship in Serbia According to Mihr, Serbian prime minister Aleksandar Vučić has proved "very sensitive to criticism, even on critical questions," as was the case with Natalija Miletic, a correspondent for Deutsche Welle Radio, who questioned him in Berlin about the media situation in Serbia and about allegations that some ministers in the Serbian government had plagiarized their diplomas, and who later received threats and offensive articles on the Serbian press. Multiple news outlets have accused Vučić of anti-democratic strongman tendencies. In July 2014, journalists associations were concerned about the freedom of the media in Serbia, in which Vučić came under criticism. In September 2015 five members of United States Congress (Edie Bernice Johnson, Carlos Curbelo, Scott Perry, Adam Kinzinger, and Zoe Lofgren) have informed Vice President of the United States Joseph Biden that Aleksandar's brother, Andrej Vučić, is leading a group responsible for deteriorating media freedom in Serbia. === Singapore === In the Republic of Singapore, Section 33 of the Films Act originally banned the making, distribution and exhibition of "party political films", at the pain of a fine not exceeding $100,000 or imprisonment for a term not exceeding two years. The Act further defines a "party political film" as any film or video (a) which is an advertisement made by or on behalf of any political party in Singapore or any body whose objects relate wholly or mainly to politics in Singapore, or any branch of such party or body; or (b) which is made by any person and directed towards any political end in Singapore In 2001, the short documentary called A Vision of Persistence on opposition politician J. B. Jeyaretnam was also banned for being a "party political film". The makers of the documentary, all lecturers at the Ngee Ann Polytechnic, later submitted written apologies and withdrew the documentary from being screened at the 2001 Singapore International Film Festival in April, having been told they could be charged in court. Another short documentary called Singapore Rebel by Martyn See, which documented Singapore Democratic Party leader Dr Chee Soon Juan's acts of civil disobedience, was banned from the 2005 Singapore International Film Festival on the same grounds and See is being investigated for possible violations of the Films Act. This law, however, is often disregarded when such political films are made supporting the ruling People's Action Party (PAP). Channel NewsAsia's five-part documentary series on Singapore's PAP ministers in 2005, for example, was not considered a party political film. Exceptions are also made when political films are made concerning political parties of other nations. Films such as Michael Moore's 2004 documentary Fahrenheit 911 are thus allowed to screen regardless of the law. Since March 2009, the Films Act has been amended to allow party political films as long as they were deemed factual and objective by a consultative committee. Some months later, this committee lifted the ban on Singapore Rebel. === Soviet Union === Independent journalism did not exist in the Soviet Union until Mikhail Gorbachev became its leader. Gorbachev adopted glasnost (openness), political reform aimed at reducing censorship; before glasnost all reporting was directed by the Communist Party or related organizations. Pravda, the predominant newspaper in the Soviet Union, had a monopoly. Foreign newspapers were available only if they were published by communist parties sympathetic to the Soviet Union. === Spain === === Turkey === Online access to all language versions of Wikipedia was blocked in Turkey on 29 April 2017 by Erdoğan's government. Article 299 of the Turkish Penal Code deems it illegal to "Insult the President of Turkey". A person who is sentenced for a violation of this article can be sentenced to a prison term between one and four years and if the violation was made in public the verdict can be elevated by a sixth. Prosecutions often target critics of the government, independent journalists, and political cartoonists. Between 2014 and 2019, 128,872 investigations were launched for this offense and prosecutors opened 27,717 criminal cases. === United Kingdom === From December 1956 until 1974 the Irish republican political party Sinn Féin was banned from participating in elections by the Northern Ireland Government. From 1988 until 1994 the British government prevented the UK media from broadcasting the voices (but not words) of Sinn Féin and ten Irish republican and Ulster loyalist groups. === United States === In the United States, most forms of censorship are self-imposed rather than enforced by the government. The government does not routinely censor material, although state and local governments often restrict what is provided in libraries and public schools. In addition, distribution, receipt, and transmission (but not mere private possession) of obscene material may be prohibited by law. Furthermore, under FCC v. Pacifica Foundation, the FCC has the power to prohibit the transmission of indecent material over broadcast. Additionally, critics of campaign finance reform in the United States say this reform imposes widespread restrictions on political speech. === Uruguay === In 1973, a military coup took power in Uruguay, and the State practiced censorship. For example, writer Eduardo Galeano was imprisoned and later was forced to flee. His book Open Veins of Latin America was banned by the right-wing military government, not only in Uruguay, but also in Chile and Argentina. == See also == Censor bars – Basic form of censorship Collateral censorship – Type of censorship of speech Deplatforming – Administrative or political action to deny access to a platform to express opinions Media regulation – Laws on mass mediaPages displaying short descriptions of redirect targets Motion Picture Production Code, also known as Hays Code – U.S. film studio self-censorship rules (1930–1967)Pages displaying short descriptions of redirect targets Nineteen Eighty-Four – 1949 novel by George Orwell Taboo – Societal or cultural prohibition Streisand effect – Increased awareness of information caused by efforts to suppress it == References == === Works cited === Crampton, R.J. (1997), Eastern Europe in the Twentieth Century and After, Routledge, ISBN 978-0415164221 Major, Patrick; Mitter, Rana (2004), "East is East and West is West?", in Major, Patrick (ed.), Across the Blocs: Exploring Comparative Cold War Cultural and Social History, Taylor & Francis, Inc., ISBN 978-0714684642 == Further reading == Abbott, Randy. "A Critical Analysis of the Library-Related Literature Concerning Censorship in Public Libraries and Public School Libraries in the United States During the 1980s." Project for degree of Education Specialist, University of South Florida, December 1987. Biltereyst, Daniel, ed. Silencing Cinema. Palgrave/Macmillan, 2013.* Birmingham, Kevin, The Most Dangerous Book: The Battle for James Joyce's Ulysses, London (Head of Zeus Ltd), 2014, ISBN 978-1594203367 Burress, Lee. Battle of the Books. Metuchen, NJ: The Scarecrow Press, 1989. Butler, Judith, "Excitable Speech: A Politics of the Performative"(1997). Darnton, Robert, Censors at Work: How States Shaped Literature. New York: W. W. Norton. 2014. ISBN 978-0393242294. Demm, Eberhard. Censorship and Propaganda in World War I: A Comprehensive History (Bloomsbury Academic, 2019) online review Foucault, Michel, edited by Lawrence D. Kritzman. Philosophy, Culture: Interviews and Other Writings 1977–1984 (New York/London: 1988, Routledge, ISBN 0415900824) (The text Sexual Morality and the Law is Chapter 16 of the book). Gilbert, Nora. Better Left Unsaid: Victorian Novels, Hays Code Films, and the Benefits of Censorship. Stanford, CA: Stanford University Press, 2013. Hoffman, Frank. Intellectual Freedom and Censorship. Metuchen, NJ: The Scarecrow Press, 1989. Mathiesen, Kay Censorship and Access to Information Handbook of Information and Computer Ethics, Kenneth E. Himma, Herman T. Tavani, eds., John Wiley and Sons, New York, 2008 National Coalition against Censorship (NCAC). "Books on Trial: A Survey of Recent Cases." January 1985. Parker, Alison M. (1997). Purifying America: Women, Cultural Reform, and Pro-Censorship Activism, 1873–1933, University of Illinois Press. Ringmar, Erik A Blogger's Manifesto: Free Speech and Censorship in the Age of the Internet (London: Anthem Press, 2007) Terry, John David II. "Censorship: Post Pico." In School Law Update, 1986, edited by Thomas N. Jones and Darel P. Semler. Sandefur, Timothy (2008). "Censorship". In Hamowy, Ronald (ed.). The Encyclopedia of Libertarianism. Thousand Oaks, CA: Sage; Cato Institute. pp. 56–57. ISBN 978-1412965804. Silber, Radomír. Partisan Media and Modern Censorship: Media Influence On Czech Political Partisanship and the Media's Creation of Limits to Public Opposition and Control of Exercising Power in the Czech Republic in the 1990s. First edition. Brno: Tribun EU, 2017. 86 stran. Librix.eu. ISBN 978-8026311744. Silber, Radomír. (2018) On Modern Censorship in Public Service Broadcasting. Cultural and Religious Studies, Volume 3, 2018, ISSN 2328-2177. Wittern-Keller, Laura. Freedom of the Screen: Legal Challenges to State Film Censorship, 1915–1981. University Press of Kentucky 2008 Gosztonyi, Gergely. (2023) Censorship from Plato to Social Media Springer, Cham. ISBN 978-3-031-46528-4

Censorship is the suppression of speech, public communication, or other information. This may be done on the basis that such material is considered objectionable, harmful, sensitive, or "inconvenient". Censorship can be conducted by governments, private institutions, and other controlling bodies. Governments sometimes engage in censorship. Other groups or institutions may propose and petition for censorship. When an individual such as an author or other creator engages in censorship of their own works or speech, it is referred to as self-censorship. General censorship occurs in a variety of different media, including speech, books, music, films, and other arts, the press, radio, television, and the Internet for a variety of claimed reasons including national security, to control obscenity, pornography, and hate speech, to protect children or other vulnerable groups, to promote or restrict political or religious views, and to prevent slander and libel. Specific rules and regulations regarding censorship vary between legal jurisdictions and/or private organizations.

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censorship

Censorship (psychoanalysis) (wikipedia)

Censorship (psychoanalysis) (Zensur) is the force identified by Sigmund Freud as operating to separate consciousness from the unconscious mind. == In dreaming == In his 1899 The Interpretation of Dreams, Freud identified a force working to disguise the dream-thoughts so as to make them more acceptable to the dreamer. In his wartime lectures, he compared its operation to the contemporary newspapers, where blanks would reveal first-hand the work of the censor, but where allusions, circumlocutions, and other softening techniques also showed attempts to work round the censorship of thoughts in advance. He went on to characterise the motivating force, which he called "the self-observing agency as the ego-censor [Zensor], the conscience; it is this that exercises the dream-censorship [Zensur] during the night, from which the repressions of inadmissable wishful impulses proceed". Another tool used by the dream-censorship was regression to archaic symbolic forms of expression unfamiliar to the conscious mind. Where all such measures of censorship failed, however, the result could be the development of nightmares and insomnia. == Psychoanalytic extensions == Freud found the same effects of disguise and omission taking place in the construction of neurotic symptoms, under the influence of the censorship, as in dreams. He would eventually assign the role of censor to the mental agency he would term the superego. == Criticism == Sartre questioned how the censorship could operate unless it was already aware of the contents of the unconscious, and thought the phenomena Freud described could be better understood in terms of bad faith. == See also == Ego ideal Screen memory Superego resistance == References == == External links == About censorship (Freud)

Censorship (psychoanalysis) (Zensur) is the force identified by Sigmund Freud as operating to separate consciousness from the unconscious mind.

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censorship

Censorship in France (wikipedia)

France has a long history of governmental censorship, particularly in the 16th to 19th centuries, but today freedom of press is guaranteed by the French Constitution and instances of governmental censorship are limited. There was strong governmental control over radio and television during the 1950s–1970s. Today, the CSA is only responsible for overseeing the observance of French law by the media, such as the 1990 Gayssot Act which prohibits racist and religious hate speech (which historical revisionism, in particular but not only Holocaust denial falls under), and time period allocated to each political party during pre-electoral periods. Furthermore, other laws prohibit homophobic hate speech, and a 1970 law prohibits the advocacy of illegal drugs. In 2016, a television ad which advocated that babies with Down Syndrome should not be aborted solely because of their syndrome ran. It was ruled anti-abortion speech and removed. Each of these laws has been criticized by some groups, either from the left (especially concerning the 1970 law on drugs) or from the far right (in particular concerning the 1990 Gayssot Act or the laws prohibiting homophobic attacks). Others express the need for minorities to be protected from hate speech which may lead, according to them, to heinous acts and hate crimes, while still others claim that one cannot tolerate free speech concerning drugs as it is a matter of public health and moral order. However, the 2005 vote of the law on colonialism voted by the UMP conservative parliamentary majority has lifted a debate, especially among historians, concerning the legitimacy and relevancy of such "memory laws." Although a fair amount of historians are opposed to such laws, few advocate their repeal because they think that repealing democratically agreed upon laws would be a greater evil. Finally, critics, in particular, but not only, from the left wing, have criticized economic censorship, in particular through concentration of media ownership (Bouygues' influence, for instance, on TF1), or the fact that Dassault or Lagardère, both military firms, control several newspapers in France, such as Le Figaro (owned by Dassault). Overall, freedom of press is guaranteed by the French Constitution but several effective cases of censorship against newspapers (Le Canard enchaîné, Charlie Hebdo and Hara-Kiri newspapers, etc.), films, or radio-shows, have been registered in the history of the Fifth Republic, founded in 1958. According to Human Rights Watch, 6 percent of French people investigated for "apology for terrorism" are under the age of 14. == History of freedom of press and censorship in France == === To the 18th century === Censorship in France may be traced to the Middle Ages. In 1275 Philip III of France put Parisian scriptoria under the control of the University of Paris which inspected manuscript books to verify that they were correctly copied. Correctness of text, not content, was the concern until the early 16th century, when tracts by Martin Luther were printed. On June 13, 1521, Francis I of France decreed that all (religious) books had to be read and approved by the Faculty of Theology of the university, and on August 3, 1521, Parlement ordered that all Lutheran books must be deposited within one week. In 1526, the Parlement of Paris and the Sorbonne issued a ban on the publishing of the Bible in French. On January 13, 1535, an extreme statute was enacted forbidding all printing under threat of hanging and closing all bookshops. This law was quickly abandoned, and Parlement formed a commission to review book printing. In 1536 it was ordered that all medical books must be approved by the Medical Faculty of the university, and actions were taken against certain publishers of books on medicine and astrology. In 1544, the university banned the printing of any book not approved by the appropriate University officials. In 1543, the Faculty of Theology issued its first Index of prohibited books, all religious, preceding by 16 years the Vatican's issuance of the Index Librorum Prohibitorum in 1559. The Edict of Châteaubriant issued on June 27, 1551, prohibited possessing any books listed on the university's Index; translating the Bible or works of the Church Fathers; importing books from Geneva and other places not under the Church's control; or printing or selling of any religious books written in the last 40 years. The state itself began to take a greater role in censorship over the university and in 1566, the Ordonnance of Moulins was issued, banning the writing, printing or selling of defamatory books attacking individuals' good reputations and requiring that all books published must be approved and include the privilege and the great seal. The state control was strengthened in 1571 by the edict of Gaillon which placed enforcement of the censorship laws in the Chancellor's office instead of the university. The concern of the censors was "heresy, sedition and personal libel" until 1629, when censorship began to focus also on immorality and indecency. "Nevertheless ... the government was never so much concerned about looseness of morals as it was about freedom of thought." Manuscripts had to be approved by the Chancellor before publication and a register of permits was maintained. During the 17th century, the university and the state fought over control of censorship, which was haphazard. In 1653, the university was stripped of authority and replaced by royal censors. The royal censors office expanded in the 18th century and banned hundreds of titles. Books that were approved were required to include the censor's name and certificate of approval. Censorship was eventually under the authority of the office of the Director of the Book Trade, the most famous of which was Lamoignon de Malesherbes. Penalties for violations ranged from confiscation of books which often were burned, fines, imprisonment and even death. In the later 18th century these rules were increasingly evaded by printers and booksellers. === 19th century === The loi sur la liberté de la presse of 29 July 1881 was passed under the French Third Republic in 1881 by the then-dominant Opportunist Republicans who sought to liberalise the press and promote free public discussion. The new law swept away a swathe of earlier statutes, stating at the outset the principle that "Printing and publication are free". Following Auguste Vaillant's assassination attempt, the first anti-terrorist laws was voted in 1893, which were quickly denounced as lois scélérates. These laws severely restricted freedom of expression. The first one condemned apology of any felony or crime as a felony itself, permitting widespread censorship of the press. The second one allowed to condemn any person directly or indirectly involved in a propaganda of the deed act, even if no killing was effectively carried on. The last one condemned any person or newspaper using anarchist propaganda (and, by extension, socialist libertarians present or former members of the International Workingmen's Association (IWA): 1. Either by provocation or apology [...] incited one or more persons to commit either robbery, or the crimes of murder, pillage, or arson [...]; 2. Or directed a provocation towards soldiers in the Army or Navy, with the aim of diverting them from their military duties and the obedience they owe their superiors ... would be referred to the police correctional courts and punished by imprisonment for three months to two years. === 20th century === ==== World War I ==== During World War I, postal censorship was in force, as the French state thought it necessary to control the public's morale and thus engaged in a sort of psychological warfare. Censorship was current during the war, leading to the 1915 creation of Le Canard enchaîné weekly, which used satires and other games of words to pass through "Anastasia's scissors", as was popularly called the censors (such word games still exist in Le Canard, for leisure purposes, such as the section named "Sur l'album de la Comtesse").. ==== World War II ==== France fell to German forces in May 1940. The occupying German military administration set up a propaganda effort headquartered in Paris, with branches (Propagandastaffel) in major cities. The propaganda effort included monitoring and censorship of the French press and of publishing, film, advertising and speeches. ==== Fifth Republic ==== Censorship laws were revoked with the founding of the Fifth Republic in 1958, although cases of censorship still occurred (in particular concerning films or satirical newspapers). The proclamation of the state of emergency, used during the Algerian War (1954–1962) and also in 2005, during the civil unrest, allows the state to legally censor news articles and other media productions (used during the Algerian War, this censorship disposition was not used in 2005).. Henri Alleg's book La Question denouncing torture by the French Army during the Algerian war was censored, as well as other similar books and films, such as The Battle of Algiers. In 2003 , UMP deputy Nadine Morano called on Interior Minister (UMP) Nicolas Sarkozy to prosecute the hip hop group Sniper for inciting violence against the police. after the 2005 riots 200 UMP deputies, led by François Grosdidier, brought a petition against several groups including Fabe, Sniper, 113, Lunatic, and others. In March 2006 Grosdidier, frustrated by failure of court actions, proposed a law (no.2957) to amend the law of 29 July 1881 to explicitly remove speech protections for music and sanction racism against the majority by a minority. In 1987 a law repressing inciting suicide was passed, after a best-selling book called Suicide, mode d'emploi was published in 1982. The bill was first adopted by the Senate in 1983; in 1987, during the debates before the National Assembly, the book was cited by name as a prime example of what was to be banned. This book, written by two anarchists (Claude Guillon and Yves Le Bonniec), contained a historic and theoretical account of suicide, as well as a critical overview of ways to commit suicide. The book could not be rereleased in 1989 because of that law. The book is thus censored de facto, unavailable in all libraries and bookshops in France. It has never been translated into English. === 21st century === In 2006, Interior Minister and former President of the Republic Nicolas Sarkozy was accused of interfering in the management of Paris Match after it published photos of Cécilia Sarkozy with another man in New York. The firing of the Paris Match director by Hachette Filipacchi Médias coincided with several other instances of self-censorship in French media. In April 2013 a volunteer with administrator's access to the French language Wikipedia was summoned by the direction centrale du Renseignement intérieur (Central Directorate of Homeland Intelligence, DCRI), a division of France's interior ministry. The volunteer was ordered to take down an article that had been online since 2009 concerning a military radio relay station at Pierre-sur Haute. DCRI claimed the article contained classified military information, for reasons that to date remain unclear, and broke French law. The volunteer, who had no connection with the article, explained "that's not how Wikipedia works" and told them he had no right to interfere with editorial content, but was told he would be held in custody and charged if he failed to comply. The article was promptly restored by a Swiss Wikipedia contributor. Christophe Henner, vice-president of Wikimedia France, said "if the DCRI comes up with the necessary legal papers we will take down the page. We have absolutely no problem with that and have made it a point of honour to respect legal injunctions; it's the method the DCRI used that is shocking." On 15 December 2017, France's Constitutional Court rejected a bill to make visiting terrorist websites a criminal offence, citing "inviolability of freedom of communication and expression" as a reason. In 2024, the sui generis collectivity of France, New Caledonia in the Pacific (also part of EEA) banned TikTok, after riots, and also banned public gatherings. == Political speech == Individuals in these cases have been prosecuted for expressing political agreement or disagreement in a particular manner. In 2008, left wing activist Herve Eon was convicted for a sign he had made and given a €30 fine. The sign, which was held near the car of former President Nicolas Sarkozy, read "get lost jerk", echoing a statement Sarkozy himself had made to a critic at a public event. In 2013, the European Court of Human Rights overturned the ruling and criticized the French decision, stating the remark was protected for being satirical. In 2013 Laure Pora, the head of a Paris chapter of LGBT rights group ACT UP, counter-protested at a rally against abortion. She called the President of an opposing group a "homophobe" and had activists distribute fliers with this message. In 2016, judges convicted Pora of a hate crime and fined her €2,300, ruling that "homophobe" was a slur in violation of French law. This conviction was however definitely cancelled by the Court of Cassation in January 2018: the Court found that Pora's words were within the acceptable limits of freedom of speech. In 2015, France upheld twelve convictions which prosecuted BDS activists for selling T-shirts which read "Long live Palestine, boycott Israel". This ruling was overturned by the European Court of Human Rights in 2020. == Linguistic censorship == The Toubon law enacted in 1994 has the cultural goal of "reaffirming the position of the French language". It requires "the compulsory use of the French language in all [public] written, ...radio and television advertising..." As a direct consequence, advertising industry workers in France have expressed "frustration with regards to what many of them perceive as linguistic censorship." Computer software developed outside France has to have its user interface and instruction manuals translated into French to be legally used by companies in France, due to the provision of the Toubon law applying to all workplaces that "any document that contains obligations for the employee or provisions whose knowledge is necessary for the performance of one's work must be written in French." Also under this law, French language is required in all audiovisual programs, with exceptions for musical works and 'original version' films. Under a related law for television, a minimum of 60 per cent of the movies and TV series must be produced in European countries and 40 per cent in Francophone countries, and these minimums must be met during evening prime-time as well as daily overall time. The latter law is not linguistic censorship because it applies to television programs that are dubbed into French; rather it is a restriction of foreign-produced cultural content. In another law that involves censorship of both linguistic and foreign-produced content, songs in the French language on radio are protected by a minimum quota system. == Press == The press is largely unrestricted by law in France, although indirect pressures are sometimes applied to prevent publication of materials against the interests of the government or influential industries. Involvement of the government and major industrial groups, sometimes with political ties, with certain press organizations sometimes raises questions as to the ability of the press to remain truly independent and unrestricted. Examples include: the Agence France-Presse (AFP), an internationally active news agency used by the media worldwide, is a public corporation nominally independent from the government, but derives a lot of its revenue from sales to government; Radio France International (RFI) is funded by the Minister of Foreign Affairs, and is sometimes criticized for its cover of former French colonies Serge Dassault, businessman involved in warplanes, and thus in government procurement contracts, (see Dassault Aviation) and senator from the UMP party, owns newspapers including Le Figaro; he famously indicated that he intended his papers to reflect only "healthy ideas" (idées saines) and that left-wing ideas were unhealthy; the Bouygues group, a major operator of public works and thus of government procurement contracts, owns the TF1 TV channel, which has the largest audience. Specifically, the talk-show Droit de réponse (Right to reply), shown on prime-time Saturday evening by Michel Polac, was suppressed after criticizing the bridge of Ré Island built by Bouygues. In addition, most of the press depends on advertisement to generate revenue; the question of independence from advertisers is a constant and contentious one, with repeat assertions that undesirable investigations were taken away from TV broadcasts. However, there are examples of independence of the press, including the Canard enchaîné, a newspaper that is known for its scoops and publication thereof, even against the will of the government. In order to remain independent, the Canard does not accept advertising. Human rights defenders were alarmed regarding France's lower house of parliament debating a controversial bill advocated by President Macron's party, and say the measure would hurt press freedoms and will result in "massive" self-censorship. == Theatre == Victor Hugo's 1832 play Le roi s'amuse was banned after one performance. Though it depicts the escapades of Francis I of France, censors of the time believed that it also contained insulting references to King Louis-Philippe. Hugo brought a suit to permit the performance of the play, which he lost but it propelled him into celebrity as a defender of freedom of speech. == Cinema == All films intended for theatrical release have to be granted a visa by the Ministry of Culture, upon the recommendation of Commission for film classification (Commission de classification cinématographique), which can give a film one of five ratings: Tous publics (universal/U): suitable for all audiences Avertissement (!): some scenes may disturb young viewers. Can be used in conjunction with any rating as a warning. Interdit aux moins de 12 ans (-12): Forbidden for under 12s (likes as the Children's Online Privacy Protection Act, which the privacy law prohibits children under 13 years of age to use social media) Interdit aux moins de 16 ans (-16): Forbidden for under 16s Interdit aux moins de 18 ans (-18): Forbidden for under 18s but not pornographic. Usually used for movies containing unsimulated sex (e.g. Ken Park in 2003) or extreme violence/cruelty (e.g. 1971's A Clockwork Orange) Interdit aux moins de 18 ans classé X (-18 or X): Forbidden for under 18s and pornographic. This is not a rating per se and it is equivalent to the American "unrated" rank as such films are not played in movie theaters. Cinemas are bound by law to prevent underaged audiences from viewing films and may be fined if they fail to do so. The Commission cannot make cuts to a film, but it can ban it, although this latter power is rarely used. In practice, this means that most films in France are categorized rather than censored. Although there are no written guidelines as to what sort of content should receive which rating and ratings are given on a case-by-case basis, the commissioners typically cite violent, sexual and drug related content (especially if it is deemed to be graphic or gratuitous) as reasons for higher ratings. By contrast little attention is paid to strong language. However sexual content is much less likely to produce a high rating than in many other countries, including the United States. Films that have received mild ratings in France compared to the U.S. include: American Beauty, U (rated R in the US) Fat Girl, -12 (unrated in the US) Borat: Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan, U (rated R in US) Eyes Wide Shut, U! reclassified to U (rated R in US) Kids, -12 (originally rated NC-17 in the US) Taxi Driver, -16, reclassified to -12 Braveheart, U! reclassified to U (rated R in US) The Exorcist, -16, reclassified to -12 Van Helsing, U, (rated PG-13 in the US) Showgirls, -12 (rated NC-17 in US) Shame (2011 film), -12 (rated NC-17 in US) Killer Joe (film), -12 (rated NC-17 in US) Blue Valentine (film), U (originally rated NC-17 in US, appealed to an R rating) The Royal Tenenbaums, U (rated R in US) Kick-Ass, U! (rated R in US) Team America: World Police (cut version), U! (rated R in US) Man Bites Dog, -12 (rated NC-17 in US) Mulholland Drive, U (rated R in US) Inland Empire, U (rated R in US) Baise-Moi, -16, reclassified to -18 (unrated in US) Fifty Shades of Grey, -12 (rated R in US) The Lobster, U! (rated R in US) Sausage Party, -12 (rated R in US) Parasite (2019 film), U! (rated R in US) Blue is the Warmest Colour, -12 (rated NC-17 in US) Spy × Family Code: White, U (rated PG-13 in US) == Television == The Conseil supérieur de l'audiovisuel (CSA) leaves the TV channels the choice of classification of a program, but can impose penalties if the classification is too low. There are five classifications for television programs: Tous publics (universal/U): suitable for all audiences Déconseillé aux moins de 10 ans (-10): Not recommended for anyone under 10s (excluded from shows for children) Déconseillé aux moins de 12 ans (-12): Not recommended for anyone under 12s (broadcast mostly after 10:00pm but occasionally after 8:30pm) Déconseillé aux moins de 16 ans (-16): Not recommended for anyone under 16s (broadcast after 10:30pm) Interdit aux moins de 18 ans (-18): Forbidden to anyone under 18s (broadcast between 0:00am and 5:00am) Classification of films can vary between the theatrical release and television broadcast. For example, Zombieland has been classified "Tous publics" in cinema, but when it was broadcast on TV, it was classified -16. The CSA is quite permissive about offensive language and sex in relation to the United States and in the United Kingdom. For example, South Park can be broadcast at any time of the day, except adjacent to youth programming, because it is classified -10. Note that cinema-only and VOD channels have different rules. === Classification details === Classification is made by the channels through a "viewing committee" which uses some guidelines proposed by the Conseil supérieur de l'audiovisuel (CSA) to decide of a classification. The CSA exerts control at the time of broadcasting, not before, and can investigate further either after a viewer's complaint or on its own behalf. Sanctions from the CSA can range from a simple warning to a broadcasting ban. Some of the questions that the CSA want to be asked by viewing committees when evaluating a show are the following. For a series, each episode is evaluated. The number and nature of the violent scenes Are the violent scenes gratuitous or important for the scenario? Are women depicted in a respectful or disrespectful way? Is sex being depicted? And how could young viewers react to such scenes? == List of censored books == Lamennais, Le Pays et le gouvernement (1840, led to Lammennais' imprisonment for a year) Henri Alleg, La Question (Minuit, 1958 — on the use of torture during the Algerian War) Frantz Fanon's The Wretched of the Earth (1961), with a preface from Jean-Paul Sartre (published by François Maspero) Mongo Beti's Cruel hand on Cameroon, autopsy of a decolonization (Maspero, 1972) censored by the Ministry of the Interior Raymond Marcellin on the request, brought forward by Jacques Foccart, of the Cameroon government, represented in Paris by the ambassador Ferdinand Oyono. Bagatelles pour un massacre, by Louis-Ferdinand Céline, for antisemitism, just like by the same author: L'Ecole des cadavres Les Beaux draps Léon Degrelle's Tintin mon copain == List of censored songs == Boris Vian, Le Déserteur (1954) JoeyStarr, "Sarkozy" (2006) == List of censored films == La Garçonne (1923) Zéro de conduite (1933) Jean-Luc Godard, Le Petit Soldat (1960) Claude Autant-Lara , Thou Shalt Not Kill (1961) from 1961 to 1963 Du - Zwischenzeichen der Sexualität (1968) Gillo Pontecorvo, The Battle of Algiers (1965) L'Essayeuse (1976) Le Mur (2011) Censored from 2012 to 2014. == CSA == The Conseil Supérieur de l'Audiovisuel (CSA) is charged to regulate televisions, both public and private. It surveys the respect of national legislation, as well as the respect of time allocated to each political party in the media during electoral periods. == Freedom of information == Freedom of information and the accountability of public servants is a constitutional right, according to the Declaration of the Rights of Man and of the Citizen. The implementing freedom of information legislation is the Loi n°78-753 du 17 juillet 1978 portant diverses mesures d'amélioration des relations entre l'administration et le public et diverses dispositions d'ordre administratif, social et fiscal (Act No. 78-753 of 17 July 1978. On various measures for improved relations between the Civil Service and the public and on various arrangements of administrative, social and fiscal nature). It sets as a general rule that citizens can demand a copy of any administrative document (in paper, digitized or other form). The commission on access to administrative documents (Commission d'Accès aux Documents Administratifs, CADA), an independent administrative authority, may help in the process. Regulations specify maximal fees of reproduction. Only final versions, not work documents, may be requested. There exist a number of exemptions: Documents established in the process of justice. Documents of cases before the national ombudsman. Documents carrying an appreciation or judgment over a named or easily identifiable person, or containing private information of that person (such as medical records), when the person requesting the document is not the person described in the document or, in some cases, from his or her family; such documents may often still be obtained after the names of the persons involved are erased; Documents for which that are already available to the public (for instance, publishing in the Journal Officiel). Documents with secrets regarding national defense or national foreign policy (though they may often be communicated after erasure of certain passages). Internal deliberations of the national executive. Documents from fiscal, customs, criminal enquiries. Certain exempted documents may still be available according to other statutes. For instance, some tax-related information about any taxpayer are available to any other taxpayer from the same tax district. CADA does not have the power to order administrations to surrender documents, though it may strongly incite them to do so. However, citizens can challenge the refusal of the administration before the administrative courts (i.e. courts hearing recourses against the executive). Unfortunately, these courts are overbooked, and citizens must often wait several years to have their rights examined in a fair trial. France has been declared guilty of excessive delays (more than 10 years) many times by the European Court of Human Rights.. == See also == Internet censorship in France Human rights in France Reporters Without Borders == Works cited == Pottinger, David Thomas (1958). The French Book Trade in the Ancien Régime, 1500-1791. Cambridge, Mass.: Harvard University Press. ISBN 9780674432581. OCLC 7385496598. == References == == Further reading == Claude Guillon, Le droit à la mort. Suicide, mode d'emploi: ses lecteurs, ses juges, Paris, Hors Texte, 2004 (ISBN 2-915286-34-5) William Hanley, A biographical dictionary of French censors 1742–1789, Ferney, Centre international d'étude du XVIIIe siècle, 2005 (ISBN 978-2-84559031-1) Hesse, Carla. (1991). Publishing and Cultural Politics in Revolutionary Paris, 1789–1810. Berkeley: University of California Press. McLeod, Jane. (2011). Licensing Loyalty: Printers, Patrons, and the State in Early Modern France. University Park: Pennsylvania State University Press. == External links == CNC Centre National de la Cinématographie, parent organisation of the Commission for film classification CSA Conseil supérieur de l'audiovisuel IFEX International Freedom of Expression Exchange Specific Sites Excluded from Google.fr and or Google.de. La Censure cinématographique en France, thesis Report by the chairman of the French Commission of film classification

France has a long history of governmental censorship, particularly in the 16th to 19th centuries, but today freedom of press is guaranteed by the French Constitution and instances of governmental censorship are limited. There was strong governmental control over radio and television during the 1950s–1970s. Today, the CSA is only responsible for overseeing the observance of French law by the media, such as the 1990 Gayssot Act which prohibits racist and religious hate speech (which historical revisionism, in particular but not only Holocaust denial falls under), and time period allocated to each political party during pre-electoral periods. Furthermore, other laws prohibit homophobic hate speech, and a 1970 law prohibits the advocacy of illegal drugs. In 2016, a television ad which advocated that babies with Down Syndrome should not be aborted solely because of their syndrome ran. It was ruled anti-abortion speech and removed. Each of these laws has been criticized by some groups, either from the left (especially concerning the 1970 law on drugs) or from the far right (in particular concerning the 1990 Gayssot Act or the laws prohibiting homophobic attacks). Others express the need for minorities to be protected from hate speech which may lead, according to them, to heinous acts and hate crimes, while still others claim that one cannot tolerate free speech concerning drugs as it is a matter of public health and moral order. However, the 2005 vote of the law on colonialism voted by the UMP conservative parliamentary majority has lifted a debate, especially among historians, concerning the legitimacy and relevancy of such "memory laws." Although a fair amount of historians are opposed to such laws, few advocate their repeal because they think that repealing democratically agreed upon laws would be a greater evil. Finally, critics, in particular, but not only, from the left wing, have criticized economic censorship, in particular through concentration of media ownership (Bouygues' influence, for instance, on TF1), or the fact that Dassault or Lagardère, both military firms, control several newspapers in France, such as Le Figaro (owned by Dassault). Overall, freedom of press is guaranteed by the French Constitution but several effective cases of censorship against newspapers (Le Canard enchaîné, Charlie Hebdo and Hara-Kiri newspapers, etc.), films, or radio-shows, have been registered in the history of the Fifth Republic, founded in 1958. According to Human Rights Watch, 6 percent of French people investigated for "apology for terrorism" are under the age of 14.

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ertu

ertu (wiktionary)

From ert (“[you] are”) + þú (“you”). Compare Swedish äru. IPA(key): /ˈɛr̥tʏ/ ertu you are, are you Ertu is much more used than ert þú which is most often used if the speaker wishes to sound very formal, or if he intends to add emphasis to "þú":

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ertu

National Media Authority (wikipedia)

The National Media Authority (NTU; Arabic: الهيئة الوطنية للإعلام, romanized: al-Hayʾa l-Waṭaniyya li-l-ʾIʿlām), known until 2017 as Egyptian Radio and Television Union (ERTU; Arabic: اتحاد الإذاعة والتلفزيون المصري, romanized: Ittiḥād al-ʾIdhāʿa wa-t-Tilifizyōn al-Miṣrī), is the public broadcaster of Egypt, operated by the Egyptian government. It is a member of the European Broadcasting Union (EBU) and the Arab States Broadcasting Union (ABSU). == History == Egyptian Radio began broadcasting on 31 May 1934 in agreement with the Marconi Company. The General Manager of the station for the period was Said Basha Lotfi who presided over the station from May 1934 to December 1947. In December 1947, the contract with Marconi was suspended in favour of an Egyptian national broadcasting station. The station is known also for its call "This is Cairo" (Arabic: هنا القاهرة, romanized: Hunā l-Qāhira). It is considered the "First Program" (البرنامج الأول, al-Barnāmaj al-ʾAwwal) of the ERTU. Later on three main new radio channels were added, namely the pan-Arab Voice of the Arabs (صوت العرب, Ṣawt al-ʿArab) in 1953, Egyptian Radio's Second Programme (البرنامج الثاني, al-Barnāmaj ath-Thānī) in 1957, and the pan-Arab Middle East Radio (إذاعة الشرق الأوسط, ʾIdhāʿat ash-Sharq al-ʾAwsaṭ) in 1964. All four stations broadcast on high powered medium wave transmitters covering most of the Middle East and North and East Africa. Egyptian television began broadcasting six hours daily on 21 July 1960, with a state-run channel that held a monopoly on terrestrial broadcasts. In 1971, a new decree established the Arab Radio and Television Union, and created four distinct sectors: radio, television, engineering, and finance, each of which had a chairman who reported directly to the minister of information. The name of the Union was changed to the Egyptian Radio and Television Union, the name by which it is still known. Today, its total daily broadcast time on its various channels amounts to 490 hours. Already in 1950 its predecessor, the Egyptian State Broadcasting (الإذاعة الحكومية المصرية, al-ʾIdhāʿa l-Ḥukūmiyya l-Miṣriyya), was one of the founding members of the European Broadcasting Union in 1950. After the admittance of the Israel Broadcasting Service in 1958, it cancelled its active memberships, as did the Syrian Broadcasting Services. It was readmitted as an active member on 1 January 1985. Under previous secularist regimes, women employees wearing hijabs were not allowed on-screen until 2 September 2012, following the inauguration of the Morsi government. == Services & subsidiaries == The NMA is an Egyptian SOE that runs a large spectrum of radio, television and satellite channels, in addition to television and film production facilities. It does this directly as well as through a host of companies that include: Egyptian Media Production City Co SAE Sono Cairo Egyptian Satellites Co SAE (Nilesat) Nile Radio Network === Radio === ==== General stations ==== General Programme Radio (إذاعة البرنامج العام, ʾIdhāʿat al-Barnāmaj al-ʿĀmm) or Egyptian Radio – established in 1934 as the main channel of the network Voice of the Arabs (إذاعة صوت العرب, ʾIdhāʿat Ṣawt al-ʿArab) – established in 1953 as a pan-Arab station Second Program (البرنامج الثاني, al-Barnāmaj ath-Thānī) – established in 1957 (now replaced and converted into the Cultural Radio) Middle East Radio (إذاعة الشرق الأوسط, ʾIdhāʿat ash-Sharq al-ʾAwsaṭ) – established in 1964 as a pan-Arab station European Program Radio (إذاعة البرنامج الأوربي, ʾIdhāʿat al-Barnāmaj al-ʾŌrōbbī) – broadcasting in English, French, Greek, Italian and German ==== Specialized (thematic) stations ==== Cultural Radio (إذاعة البرنامج الثقافي, ʾIdhāʿat al-Barnāmaj ath-ʿThaqāfī) – replaced the Second Program Youth and Sports Radio (إذاعة الشباب والرياضة, ʾIdhāʿat ash-Shabāb wa-r-ʾRiyāḍa) – established in 1975) Radio Greater Cairo (إذاعة القاهرة الكبرى, ʾIdhāʿat al-Qāhira l-Kubrā) – established in 1981 Songs Radio (إذاعة الأغاني, ʾIdhāʿat al-ʾAghānī) – established in 2000 News and Music Radio (إذاعة الأخبار والموسيقى, ʾIdhāʿat al-ʾAkhbār wa-l-Mūsīqā) Radio Masr or (إذاعة راديو مصر, ʾIdhāʿat Rādiyō Miṣr) or Egypt Radio – established in 2009 Al Qur'an al Karim Radio (إذاعة القرآن الكريم, ʾIdhāʿat al-Qurʾān al-Karīm) – Muslim religious broadcasting Educational Radio (الإذاعة التعليمية, al-ʾIdhāʿa t-Taʿlīmiyya) Voice of Palestine (صوت فلسطين, Ṣawt Filasṭīn) ==== Regional programming radio stations ==== North of Saaeed Radio (إذاعة شمال الصعيد, ʾIdhāʿat Shamāl aṣ-Ṣaʿīd) Nile Valley Radio (إذاعة وادي النيل, ʾIdhāʿat Wādī n-Nīl) Middle Delta Radio (إذاعة وسط الدلتا, ʾIdhāʿat Wasṭ ad-Diltā) Radio Alexandria (إذاعة الإسكندرية, ʾIdhāʿat al-ʾIskandariyya) ==== International stations ==== Radio Cairo (International) including Radio Cairo World Service 1 to 7 (various channels, shortwave and satellite) === Television === ==== National ==== ERTU 1 – Generalist and informative programming. It began its broadcasts in 1960. ERTU 2 – focused on fiction, entertainment and current affairs programming, launched in 1961. Al Masriya – Channel aimed at the Egyptian diaspora, available since 1990. Channel Egypt ==== Regional ==== There are six state-owned broadcast and satellite channels in Egypt: Six regional channels, each providing specialized services for a number of governorates: Cairo Channel: broadcasting from Cairo and covering Greater Cairo governorates, i.e. Cairo, Giza and Qalioubia. Alexandria Channel: broadcasting from Alexandria and covering Alexandria, Al Buhayrah and parts of Matrouh. Canal Channel: broadcasting from Ismailia and covering Suez Canal governorates, i.e. Ismailia, Suez and Port Said. Delta Channel: broadcasting from Tanta and covering Central Delta governorates, i.e. Al Gharbiyah, Al Minufiyah, Ad Daqahliyah, Kafr ash Shaykh and Dimyat. Upper Channel: broadcasting from Minya and covering Northern Upper Egypt governorates, i.e. Minya, El-Fayoum, Beni Suef and Asiut. Thebes Channel: broadcasting from Aswan and covering Southern Upper Egypt governorates, i.e. Suhag, Qena, Al Uqsur and Aswan. === Nile Television === Nilesat allowed for the launch of several specialized TV channels in addition to Egyptian Satellite Channel (ESC) and Nile TV. All are owned by the Egyptian state. Specialized channels include: Al Nile Nile Culture channel Nile Comedy channel Nile Drama channel, specialized in Drama, mainly movies and TV series. Nile Educational channels, several channels for primary, preparatory, secondary, medical and language education. Nile Family channel Nile Sports channel Nile Variety channel, specialized in various forms of entertainment mainly concerts, music videos, contests and some talk shows. Tanweer channel == See also == List of radio stations in Egypt == References == == External links == Media related to Egyptian Radio and Television Union at Wikimedia Commons Official website (in Arabic) Official website (ERTU Building) (in Arabic)

The National Media Authority (NTU; Arabic: الهيئة الوطنية للإعلام, romanized: al-Hayʾa l-Waṭaniyya li-l-ʾIʿlām), known until 2017 as Egyptian Radio and Television Union (ERTU; Arabic: اتحاد الإذاعة والتلفزيون المصري, romanized: Ittiḥād al-ʾIdhāʿa wa-t-Tilifizyōn al-Miṣrī), is the public broadcaster of Egypt, operated by the Egyptian government. It is a member of the European Broadcasting Union (EBU) and the Arab States Broadcasting Union (ABSU).

12

printed circuit board

Leiterplatte (wiktionary)

Leiter (“conductor”) +‎ Platte (“plate”) Leiterplatte f (genitive Leiterplatte, plural Leiterplatten) circuit board, printed circuit board “Leiterplatte” in Duden online “Leiterplatte” in Digitales Wörterbuch der deutschen Sprache

13

printed circuit board

printed circuit board (wiktionary)

printed circuit board (plural printed circuit boards) (electronics) A flat board that holds chips and other electronic components in layers that interconnect via copper pathways, often called traces. PCB circuit board printed circuit printed circuit board on Wikipedia.Wikipedia

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printed circuit board

Printed circuit board (wikipedia)

A printed circuit board (PCB), also called printed wiring board (PWB), is a medium used to connect or "wire" components to one another in a circuit. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers in the shape designed to accept the component's terminals, generally by means of soldering, to both electrically connect and mechanically fasten them to it. Another manufacturing process adds vias, plated-through holes that allow interconnections between layers. Printed circuit boards are used in nearly all electronic products. Alternatives to PCBs include wire wrap and point-to-point construction, both once popular but now rarely used. PCBs require additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Electronic design automation software is available to do much of the work of layout. Mass-producing circuits with PCBs is cheaper and faster than with other wiring methods, as components are mounted and wired in one operation. Large numbers of PCBs can be fabricated at the same time, and the layout has to be done only once. PCBs can also be made manually in small quantities, with reduced benefits. PCBs can be single-sided (one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multi-layer (outer and inner layers of copper, alternating with layers of substrate). Multi-layer PCBs allow for much higher component density, because circuit traces on the inner layers would otherwise take up surface space between components. The rise in popularity of multilayer PCBs with more than two, and especially with more than four, copper planes was concurrent with the adoption of surface mount technology. However, multilayer PCBs make repair, analysis, and field modification of circuits much more difficult and usually impractical. The world market for bare PCBs exceeded $60.2 billion in 2014 and is estimated to reach $79 billion by 2024. == History == === Predecessors === Before the development of printed circuit boards, electrical and electronic circuits were wired point-to-point on a chassis. Typically, the chassis was a sheet metal frame or pan, sometimes with a wooden bottom. Components were attached to the chassis, usually by insulators when the connecting point on the chassis was metal, and then their leads were connected directly or with jumper wires by soldering, or sometimes using crimp connectors, wire connector lugs on screw terminals, or other methods. Circuits were large, bulky, heavy, and relatively fragile (even discounting the breakable glass envelopes of the vacuum tubes that were often included in the circuits), and production was labor-intensive, so the products were expensive. Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented a print-and-etch method in the UK, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1925 patented a method of electroplating circuit patterns. Predating the printed circuit invention, and similar in spirit, was John Sargrove's 1936–1947 Electronic Circuit Making Equipment (ECME) that sprayed metal onto a Bakelite plastic board. The ECME could produce three radio boards per minute. === Early PCBs === The Austrian engineer Paul Eisler invented the printed circuit as part of a radio set while working in the UK around 1936. In 1941 a multi-layer printed circuit was used in German magnetic influence naval mines. Around 1943 the USA began to use the technology on a large scale to make proximity fuzes for use in World War II. Such fuzes required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted a proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors, with ceramic disc capacitors and subminiature vacuum tubes soldered in place. The technique proved viable, and the resulting patent on the process, which was classified by the U.S. Army, was assigned to Globe Union. It was not until 1984 that the Institute of Electrical and Electronics Engineers (IEEE) awarded Harry W. Rubinstein the Cledo Brunetti Award for early key contributions to the development of printed components and conductors on a common insulating substrate. Rubinstein was honored in 1984 by his alma mater, the University of Wisconsin-Madison, for his innovations in the technology of printed electronic circuits and the fabrication of capacitors. This invention also represents a step in the development of integrated circuit technology, as not only wiring but also passive components were fabricated on the ceramic substrate. === Post-war developments === In 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. At around the same time in the UK work along similar lines was carried out by Geoffrey Dummer, then at the RRDE. Motorola was an early leader in bringing the process into consumer electronics, announcing in August 1952 the adoption of "plated circuits" in home radios after six years of research and a $1M investment. Motorola soon began using its trademarked term for the process, PLAcir, in its consumer radio advertisements. Hallicrafters released its first "foto-etch" printed circuit product, a clock-radio, on 1 November 1952. Even as circuit boards became available, the point-to-point chassis construction method remained in common use in industry (such as TV and hi-fi sets) into at least the late 1960s. Printed circuit boards were introduced to reduce the size, weight, and cost of parts of the circuitry. In 1960, a small consumer radio receiver might be built with all its circuitry on one circuit board, but a TV set would probably contain one or more circuit boards. Originally, every electronic component had wire leads, and a PCB had holes drilled for each wire of each component. The component leads were then inserted through the holes and soldered to the copper PCB traces. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered. The patent they obtained in 1956 was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are inefficient since drilling holes is expensive and consumes drill bits and the protruding wires are cut off and discarded. From the 1980s onward, small surface mount parts have been used increasingly instead of through-hole components; this has led to smaller boards for a given functionality and lower production costs, but with some additional difficulty in servicing faulty boards. In the 1990s the use of multilayer surface boards became more frequent. As a result, size was further minimized and both flexible and rigid PCBs were incorporated in different devices. In 1995 PCB manufacturers began using microvia technology to produce High-Density Interconnect (HDI) PCBs. === Recent advances === Recent advances in 3D printing have meant that there are several new techniques in PCB creation. 3D printed electronics (PEs) can be utilized to print items layer by layer and subsequently the item can be printed with a liquid ink that contains electronic functionalities. HDI (High Density Interconnect) technology allows for a denser design on the PCB and thus potentially smaller PCBs with more traces and/or components in a given area. As a result, the paths between components can be shorter. HDIs use blind/buried vias, or a combination that includes microvias. With multi-layer HDI PCBs the interconnection of several vias stacked on top of each other (stacked vías, instead of one deep buried via) can be made stronger, thus enhancing reliability in all conditions. The most common applications for HDI technology are computer and mobile phone components as well as medical equipment and military communication equipment. A 4-layer HDI microvia PCB is equivalent in quality to an 8-layer through-hole PCB, so HDI technology can reduce costs. HDI PCBs are often made using build-up film such as ajinomoto build-up film, which is also used in the production of flip chip packages. Some PCBs have optical waveguides, similar to optical fibers built on the PCB. == Composition == A basic PCB consists of a flat sheet of insulating material and a layer of copper foil, laminated to the substrate. Chemical etching divides the copper into separate conducting lines called tracks or circuit traces, pads for connections, vias to pass connections between layers of copper, and features such as solid conductive areas for electromagnetic shielding or other purposes. The tracks function as wires fixed in place, and are insulated from each other by air and the board substrate material. The surface of a PCB may have a coating that protects the copper from corrosion and reduces the chances of solder shorts between traces or undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist or solder mask. The pattern to be etched into each copper layer of a PCB is called the "artwork". The etching is usually done using photoresist which is coated onto the PCB, then exposed to light projected in the pattern of the artwork. The resist material protects the copper from dissolution into the etching solution. The etched board is then cleaned. A PCB design can be mass-reproduced in a way similar to the way photographs can be mass-duplicated from film negatives using a photographic printer. FR-4 glass epoxy is the most common insulating substrate. Another substrate material is cotton paper impregnated with phenolic resin, often tan or brown. When a PCB has no components installed, it is less ambiguously called a printed wiring board (PWB) or etched wiring board. However, the term "printed wiring board" has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly (PCBA). In informal usage, the term "printed circuit board" most commonly means "printed circuit assembly" (with components). The IPC preferred term for an assembled board is circuit card assembly (CCA), and for an assembled backplane it is backplane assembly. "Card" is another widely used informal term for a "printed circuit assembly". For example, expansion card. A PCB may be printed with a legend identifying the components, test points, or identifying text. Originally, silkscreen printing was used for this purpose, but today other, finer quality printing methods are usually used. Normally the legend does not affect the function of a PCBA. === Layers === A printed circuit board can have multiple layers of copper which almost always are arranged in pairs. The number of layers and the interconnection designed between them (vias, PTHs) provide a general estimate of the board complexity. Using more layers allow for more routing options and better control of signal integrity, but are also time-consuming and costly to manufacture. Likewise, selection of the vias for the board also allow fine tuning of the board size, escaping of signals off complex ICs, routing, and long term reliability, but are tightly coupled with production complexity and cost. One of the simplest boards to produce is the two-layer board. It has copper on both sides that are referred to as external layers; multi layer boards sandwich additional internal layers of copper and insulation. After two-layer PCBs, the next step up is the four-layer. The four layer board adds significantly more routing options in the internal layers as compared to the two layer board, and often some portion of the internal layers is used as ground plane or power plane, to achieve better signal integrity, higher signaling frequencies, lower EMI, and better power supply decoupling. In multi-layer boards, the layers of material are laminated together in an alternating sandwich: copper, substrate, copper, substrate, copper, etc.; each plane of copper is etched, and any internal vias (that will not extend to both outer surfaces of the finished multilayer board) are plated-through, before the layers are laminated together. Only the outer layers need be coated; the inner copper layers are protected by the adjacent substrate layers. === Component mounting === "Through hole" components are mounted by their wire leads passing through the board and soldered to traces on the other side. "Surface mount" components are attached by their leads to copper traces on the same side of the board. A board may use both methods for mounting components. PCBs with only through-hole mounted components are now uncommon. Surface mounting is used for transistors, diodes, IC chips, resistors, and capacitors. Through-hole mounting may be used for some large components such as electrolytic capacitors and connectors. The first PCBs used through-hole technology, mounting electronic components by leads inserted through holes on one side of the board and soldered onto copper traces on the other side. Boards may be single-sided, with an unplated component side, or more compact double-sided boards, with components soldered on both sides. Horizontal installation of through-hole parts with two axial leads (such as resistors, capacitors, and diodes) is done by bending the leads 90 degrees in the same direction, inserting the part in the board (often bending leads located on the back of the board in opposite directions to improve the part's mechanical strength), soldering the leads, and trimming off the ends. Leads may be soldered either manually or by a wave soldering machine. Through-hole manufacture adds to board cost by requiring many holes to be drilled accurately, and it limits the available routing area for signal traces on layers immediately below the top layer on multi-layer boards, since the holes must pass through all layers to the opposite side. Once surface-mounting came into use, small-sized SMD components were used where possible, with through-hole mounting only of components unsuitably large for surface-mounting due to power requirements or mechanical limitations, or subject to mechanical stress which might damage the PCB (e.g. by lifting the copper off the board surface). Surface-mount technology emerged in the 1960s, gained momentum in the early 1980s, and became widely used by the mid-1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be soldered directly onto the PCB surface, instead of wire leads to pass through holes. Components became much smaller and component placement on both sides of the board became more common than with through-hole mounting, allowing much smaller PCB assemblies with much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labor costs and greatly increasing production rates compared with through-hole circuit boards. Components can be supplied mounted on carrier tapes. Surface mount components can be about one-quarter to one-tenth of the size and weight of through-hole components, and passive components much cheaper. However, prices of semiconductor surface mount devices (SMDs) are determined more by the chip itself than the package, with little price advantage over larger packages, and some wire-ended components, such as 1N4148 small-signal switch diodes, are actually significantly cheaper than SMD equivalents. === Electrical properties === Each trace consists of a flat, narrow part of the copper foil that remains after etching. Its resistance, determined by its width, thickness, and length, must be sufficiently low for the current the conductor will carry. Power and ground traces may need to be wider than signal traces. In a multi-layer board one entire layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave circuits, transmission lines can be laid out in a planar form such as stripline or microstrip with carefully controlled dimensions to assure a consistent impedance. In radio-frequency and fast switching circuits the inductance and capacitance of the printed circuit board conductors become significant circuit elements, usually undesired; conversely, they can be used as a deliberate part of the circuit design, as in distributed-element filters, antennae, and fuses, obviating the need for additional discrete components. High density interconnects (HDI) PCBs have tracks and/or vias with a width or diameter of under 152 micrometers. == Materials == === Laminates === Laminates are manufactured by curing layers of cloth or paper with thermoset resin under pressure and heat to form an integral final piece of uniform thickness. They can be up to 4 by 8 feet (1.2 by 2.4 m) in width and length. Varying cloth weaves (threads per inch or cm), cloth thickness, and resin percentage are used to achieve the desired final thickness and dielectric characteristics. Available standard laminate thickness are listed in ANSI/IPC-D-275. The cloth or fiber material used, resin material, and the cloth to resin ratio determine the laminate's type designation (FR-4, CEM-1, G-10, etc.) and therefore the characteristics of the laminate produced. Important characteristics are the level to which the laminate is fire retardant, the dielectric constant (er), the loss tangent (tan δ), the tensile strength, the shear strength, the glass transition temperature (Tg), and the Z-axis expansion coefficient (how much the thickness changes with temperature). There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of the circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well known pre-preg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability. FR-4 is by far the most common material used today. The board stock with unetched copper on it is called "copper-clad laminate". With decreasing size of board features and increasing frequencies, small nonhomogeneities like uneven distribution of fiberglass or other filler, thickness variations, and bubbles in the resin matrix, and the associated local variations in the dielectric constant, are gaining importance. === Key substrate parameters === The circuitboard substrates are usually dielectric composite materials. The composites contain a matrix (usually an epoxy resin) and a reinforcement (usually a woven, sometimes nonwoven, glass fibers, sometimes even paper), and in some cases a filler is added to the resin (e.g. ceramics; titanate ceramics can be used to increase the dielectric constant). The reinforcement type defines two major classes of materials: woven and non-woven. Woven reinforcements are cheaper, but the high dielectric constant of glass may not be favorable for many higher-frequency applications. The spatially nonhomogeneous structure also introduces local variations in electrical parameters, due to different resin/glass ratio at different areas of the weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications. The substrates are characterized by several key parameters, chiefly thermomechanical (glass transition temperature, tensile strength, shear strength, thermal expansion), electrical (dielectric constant, loss tangent, dielectric breakdown voltage, leakage current, tracking resistance...), and others (e.g. moisture absorption). At the glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding Tg then exerts mechanical overload on the board components - e.g. the joints and the vias. Below Tg the thermal expansion of the resin roughly matches copper and glass, above it gets significantly higher. As the reinforcement and copper confine the board along the plane, virtually all volume expansion projects to the thickness and stresses the plated-through holes. Repeated soldering or other exposition to higher temperatures can cause failure of the plating, especially with thicker boards; thick boards therefore require a matrix with a high Tg. The materials used determine the substrate's dielectric constant. This constant is also dependent on frequency, usually decreasing with frequency. As this constant determines the signal propagation speed, frequency dependence introduces phase distortion in wideband applications; as flat a dielectric constant vs frequency characteristics as is achievable is important here. The impedance of transmission lines decreases with frequency, therefore faster edges of signals reflect more than slower ones. Dielectric breakdown voltage determines the maximum voltage gradient the material can be subjected to before suffering a breakdown (conduction, or arcing, through the dielectric). Tracking resistance determines how the material resists high voltage electrical discharges creeping over the board surface. Loss tangent determines how much of the electromagnetic energy from the signals in the conductors is absorbed in the board material. This factor is important for high frequencies. Low-loss materials are more expensive. Choosing unnecessarily low-loss material is a common engineering error in high-frequency digital design; it increases the cost of the boards without a corresponding benefit. Signal degradation by loss tangent and dielectric constant can be easily assessed by an eye pattern. Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water also may be soaked by capillary forces through voids in the materials and along the reinforcement. Epoxies of the FR-4 materials are not too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water is about 73, compared to about 4 for common circuit board materials. Absorbed moisture can also vaporize on heating, as during soldering, and cause cracking and delamination, the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required to dry them prior to soldering. === Common substrates === Often encountered materials: FR-2, phenolic paper or phenolic cotton paper, paper impregnated with a phenol formaldehyde resin. Common in consumer electronics with single-sided boards. Electrical properties inferior to FR-4. Poor arc resistance. Generally rated to 105 °C. FR-4, a woven fiberglass cloth impregnated with an epoxy resin. Low water absorption (up to about 0.15%), good insulation properties, good arc resistance. Very common. Several grades with somewhat different properties are available. Typically rated to 130 °C. Aluminum, or metal core board or insulated metal substrate (IMS), clad with thermally conductive thin dielectric - used for parts requiring significant cooling - power switches, LEDs. Consists of usually single, sometimes double layer thin circuit board based on e.g. FR-4, laminated on aluminum sheet metal, commonly 0.8, 1, 1.5, 2 or 3 mm thick. The thicker laminates sometimes also come with thicker copper metalization. Flexible substrates - can be a standalone copper-clad foil or can be laminated to a thin stiffener, e.g. 50-130 μm Kapton or UPILEX, a polyimide foil. Used for flexible printed circuits, in this form common in small form-factor consumer electronics or for flexible interconnects. Resistant to high temperatures. Pyralux, a polyimide-fluoropolymer composite foil. Copper layer can delaminate during soldering. Less-often encountered materials: FR-1, like FR-2, typically specified to 105 °C, some grades rated to 130 °C. Room-temperature punchable. Similar to cardboard. Poor moisture resistance. Low arc resistance. FR-3, cotton paper impregnated with epoxy. Typically rated to 105 °C. FR-5, woven fiberglass and epoxy, high strength at higher temperatures, typically specified to 170 °C. FR-6, matte glass and polyester G-10, woven glass and epoxy - high insulation resistance, low moisture absorption, very high bond strength. Typically rated to 130 °C. G-11, woven glass and epoxy - high resistance to solvents, high flexural strength retention at high temperatures. Typically rated to 170 °C. CEM-1, cotton paper and epoxy CEM-2, cotton paper and epoxy CEM-3, non-woven glass and epoxy CEM-4, woven glass and epoxy CEM-5, woven glass and polyester PTFE, ("Teflon") - expensive, low dielectric loss, for high frequency applications, very low moisture absorption (0.01%), mechanically soft. Difficult to laminate, rarely used in multilayer applications. PTFE, ceramic filled - expensive, low dielectric loss, for high frequency applications. Varying ceramics/PTFE ratio allows adjusting dielectric constant and thermal expansion. RF-35, fiberglass-reinforced ceramics-filled PTFE. Relatively less expensive, good mechanical properties, good high-frequency properties. Alumina, a ceramic. Hard, brittle, very expensive, very high performance, good thermal conductivity. Polyimide, a high-temperature polymer. Expensive, high-performance. Higher water absorption (0.4%). Can be used from cryogenic temperatures to over 260 °C. === Copper thickness === Copper thickness of PCBs can be specified directly or as the weight of copper per area (in ounce per square foot) which is easier to measure. One ounce per square foot is 1.344 mils or 34 micrometers thickness. Heavy copper is a layer exceeding three ounces of copper per ft2, or approximately 0.0042 inches (4.2 mils, 105 μm) thick. Heavy copper layers are used for high current or to help dissipate heat. On the common FR-4 substrates, 1 oz copper per ft2 (35 μm) is the most common thickness; 2 oz (70 μm) and 0.5 oz (17.5 μm) thickness is often an option. Less common are 12 and 105 μm, 9 μm is sometimes available on some substrates. Flexible substrates typically have thinner metalization. Metal-core boards for high power devices commonly use thicker copper; 35 μm is usual but also 140 and 400 μm can be encountered. In the US, copper foil thickness is specified in units of ounces per square foot (oz/ft2), commonly referred to simply as ounce. Common thicknesses are 1/2 oz/ft2 (150 g/m2), 1 oz/ft2 (300 g/m2), 2 oz/ft2 (600 g/m2), and 3 oz/ft2 (900 g/m2). These work out to thicknesses of 17.05 μm (0.67 thou), 34.1 μm (1.34 thou), 68.2 μm (2.68 thou), and 102.3 μm (4.02 thou), respectively. 1/2 oz/ft2 foil is not widely used as a finished copper weight, but is used for outer layers when plating for through holes will increase the finished copper weight Some PCB manufacturers refer to 1 oz/ft2 copper foil as having a thickness of 35 μm (may also be referred to as 35 μ, 35 micron, or 35 mic). 1/0 – denotes 1 oz/ft2 copper one side, with no copper on the other side. 1/1 – denotes 1 oz/ft2 copper on both sides. H/0 or H/H – denotes 0.5 oz/ft2 copper on one or both sides, respectively. 2/0 or 2/2 – denotes 2 oz/ft2 copper on one or both sides, respectively. == Construction == === Design === Manufacturing starts from the fabrication data generated by computer aided design, and component information. The fabrication data is read into the CAM (Computer Aided Manufacturing) software. CAM performs the following functions: Input of the fabrication data. Verification of the data Compensation for deviations in the manufacturing processes (e.g. scaling to compensate for distortions during lamination) Panelization Output of the digital tools (copper patterns, drill files, inspection, and others) Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. Rub-on dry transfers of common component footprints increased efficiency. Traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout. The finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards. Modern PCBs are designed with dedicated layout software, generally in the following steps: Schematic capture through an electronic design automation (EDA) tool. Card dimensions and template are decided based on required circuitry and enclosure of the PCB. The positions of the components and heat sinks are determined. Layer stack of the PCB is decided, with one to tens of layers depending on complexity. Ground and power planes are decided. A power plane is the counterpart to a ground plane and behaves as an AC signal ground while providing DC power to the circuits mounted on the PCB. Signal interconnections are traced on signal planes. Signal planes can be on the outer as well as inner layers. For optimal EMI performance high frequency signals are routed in internal layers between power or ground planes. Line impedance is determined using dielectric layer thickness, routing copper thickness and trace-width. Trace separation is also taken into account in case of differential signals. Microstrip, stripline or dual stripline can be used to route signals. Components are placed. Thermal considerations and geometry are taken into account. Vias and lands are marked. Signal traces are routed. Electronic design automation tools usually create clearances and connections in power and ground planes automatically. Fabrication data consists of a set of Gerber files, a drill file, and a pick-and-place file. === Panelization === Several small printed circuit boards can be grouped together for processing as a panel. A panel consisting of a design duplicated n-times is also called an n-panel, whereas a multi-panel combines several different designs onto a single panel. The outer tooling strip often includes tooling holes, a set of panel fiducials, a test coupon, and may include hatched copper pour or similar patterns for even copper distribution over the whole panel in order to avoid bending. The assemblers often mount components on panels rather than single PCBs because this is efficient. Panelization may also be necessary for boards with components placed near an edge of the board because otherwise the board could not be mounted during assembly. Most assembly shops require a free area of at least 10 mm around the board. ==== Depaneling ==== The panel is eventually broken into individual PCBs along perforations or grooves in the panel through milling or cutting. For milled panels a common distance between the individual boards is 2–3 mm. Today depaneling is often done by lasers which cut the board with no contact. Laser depaneling reduces stress on the fragile circuits, improving the yield of defect-free units. === Copper patterning === The first step is to replicate the pattern in the fabricator's CAM system on a protective mask on the copper foil PCB layers. Subsequent etching removes the unwanted copper unprotected by the mask. (Alternatively, a conductive ink can be ink-jetted on a blank (non-conductive) board. This technique is also used in the manufacture of hybrid circuits.) Silk screen printing uses etch-resistant inks to create the protective mask. Photoengraving uses a photomask and developer to selectively remove a UV-sensitive photoresist coating and thus create a photoresist mask that will protect the copper below it. Direct imaging techniques are sometimes used for high-resolution requirements. Experiments have been made with thermal resist. A laser may be used instead of a photomask. This is known as maskless lithography or direct imaging. PCB milling uses a two or three-axis mechanical milling system to mill away the copper foil from the substrate. A PCB milling machine (referred to as a 'PCB Prototyper') operates in a similar way to a plotter, receiving commands from the host software that control the position of the milling head in the x, y, and (if relevant) z axis. Laser resist ablation involves spraying black paint onto copper clad laminate, then placing the board into CNC laser plotter. The laser raster-scans the PCB and ablates (vaporizes) the paint where no resist is wanted. (Note: laser copper ablation is rarely used and is considered experimental.) Laser etching, in which the copper may be removed directly by a CNC laser. Like PCB milling above, this is used mainly for prototyping. EDM etching uses an electrical discharge to remove a metal from a substrate submerged into a dielectric fluid. The method chosen depends on the number of boards to be produced and the required resolution. Large volume Silk screen printing – Used for PCBs with bigger features Photoengraving – Used when finer features are required Small volume Print onto transparent film and use as photo mask along with photo-sensitized boards, then etch. (Alternatively, use a film photoplotter.) Laser resist ablation PCB milling Laser etching Hobbyist Laser-printed resist: Laser-print onto toner transfer paper, heat-transfer with an iron or modified laminator onto bare laminate, soak in water bath, touch up with a marker, then etch. Vinyl film and resist, non-washable marker, some other methods. Labor-intensive, only suitable for single boards. === Etching === The process by which copper traces are applied to the surface is known as etching after the subtractive method of the process, though there are also additive and semi-additive methods. Subtractive methods remove copper from an entirely copper-coated board to leave only the desired copper pattern. The simplest method, used for small-scale production and often by hobbyists, is immersion etching, in which the board is submerged in etching solution such as ferric chloride. Compared with methods used for mass production, the etching time is long. Heat and agitation can be applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to splash boards with etchant; the process has become commercially obsolete since it is not as fast as spray etching. In spray etching, the etchant solution is distributed over the boards by nozzles, and recirculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and etchant composition gives predictable control of etching rates and high production rates. As more copper is consumed from the boards, the etchant becomes saturated and less effective; different etchants have different capacities for copper, with some as high as 150 grams of copper per liter of solution. In commercial use, etchants can be regenerated to restore their activity, and the dissolved copper recovered and sold. Small-scale etching requires attention to disposal of used etchant, which is corrosive and toxic due to its metal content. The etchant removes copper on all surfaces not protected by the resist. "Undercut" occurs when etchant attacks the thin edge of copper under the resist; this can reduce conductor widths and cause open-circuits. Careful control of etch time is required to prevent undercut. Where metallic plating is used as a resist, it can "overhang" which can cause short-circuits between adjacent traces when closely spaced. Overhang can be removed by wire-brushing the board after etching. In additive methods the pattern is electroplated onto a bare substrate using a complex process. The advantage of the additive method is that less material is needed and less waste is produced. In the full additive process the bare laminate is covered with a photosensitive film which is imaged (exposed to light through a mask and then developed which removes the unexposed film). The exposed areas are sensitized in a chemical bath, usually containing palladium and similar to that used for through hole plating which makes the exposed area capable of bonding metal ions. The laminate is then plated with copper in the sensitized areas. When the mask is stripped, the PCB is finished. Semi-additive is the most common process: The unpatterned board has a thin layer of copper already on it. A reverse mask is then applied (Unlike a subtractive process mask, this mask exposes those parts of the substrate that will eventually become the traces). Additional copper is then plated onto the board in the unmasked areas; copper may be plated to any desired weight. Tin-lead or other surface platings are then applied. The mask is stripped away and a brief etching step removes the now-exposed bare original copper laminate from the board, isolating the individual traces. Some single-sided boards which have plated-through holes are made in this way. General Electric made consumer radio sets in the late 1960s using additive boards. The (semi-)additive process is commonly used for multi-layer boards as it facilitates the plating-through of the holes to produce conductive vias in the circuit board. Industrial etching is usually done with ammonium persulfate or ferric chloride. For PTH (plated-through holes), additional steps of electroless deposition are done after the holes are drilled, then copper is electroplated to build up the thickness, the boards are screened, and plated with tin/lead. The tin/lead becomes the resist leaving the bare copper to be etched away. === Lamination === Multi-layer printed circuit boards have trace layers inside the board. This is achieved by laminating a stack of materials in a press by applying pressure and heat for a period of time. This results in an inseparable one piece product. For example, a four-layer PCB can be fabricated by starting from a two-sided copper-clad laminate, etch the circuitry on both sides, then laminate to the top and bottom pre-preg and copper foil. It is then drilled, plated, and etched again to get traces on top and bottom layers. The inner layers are given a complete machine inspection before lamination because mistakes cannot be corrected afterwards. Automatic optical inspection (AOI) machines compare an image of the board with the digital image generated from the original design data. Automated Optical Shaping (AOS) machines can then add missing copper or remove excess copper using a laser, reducing the number of PCBs that have to be discarded. PCB tracks can have a width of just 10 micrometers. === Drilling === Holes through a PCB are typically drilled with drill bits coated with tungsten carbide. Coated tungsten carbide is used because board materials are abrasive. High-speed-steel bits would dull quickly, tearing the copper and ruining the board. Drilling is done by computer-controlled drilling machines, using a drill file or Excellon file that describes the location and size of each drilled hole. ==== Vias ==== Holes may be made conductive, by electroplating or inserting hollow metal eyelets, to connect board layers. Some conductive holes are intended for the insertion of through-hole-component leads. Others used to connect board layers, are called vias. ==== Micro vias ==== When vias with a diameter smaller than 76.2 micrometers are required, drilling with mechanical bits is impossible because of high rates of wear and breakage. In this case, the vias may be laser drilled—evaporated by lasers. Laser-drilled vias typically have an inferior surface finish inside the hole. These holes are called micro vias and can have diameters as small as 10 micrometers. ==== Blind and buried vias ==== It is also possible with controlled-depth drilling, laser drilling, or by pre-drilling the individual sheets of the PCB before lamination, to produce holes that connect only some of the copper layers, rather than passing through the entire board. These holes are called blind vias when they connect an internal copper layer to an outer layer, or buried vias when they connect two or more internal copper layers and no outer layers. Laser drilling machines can drill thousands of holes per second and can use either UV or CO2 lasers. The hole walls for boards with two or more layers can be made conductive and then electroplated with copper to form plated-through holes. These holes electrically connect the conducting layers of the PCB. ==== Smear ==== For multi-layer boards, those with three layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by Plasma etching. The de-smear process ensures that a good connection is made to the copper layers when the hole is plated through. On high reliability boards a process called etch-back is performed chemically with a potassium permanganate based etchant or plasma etching. The etch-back removes resin and the glass fibers so that the copper layers extend into the hole and as the hole is plated become integral with the deposited copper. === Plating and coating === Proper plating or surface finish selection can be critical to process yield, the amount of rework, field failure rate, and reliability. PCBs may be plated with solder, tin, or gold over nickel. After PCBs are etched and then rinsed with water, the solder mask is applied, and then any exposed copper is coated with solder, nickel/gold, or some other anti-corrosion coating. Matte solder is usually fused to provide a better bonding surface for bare copper. Treatments, such as benzimidazolethiol, prevent surface oxidation of bare copper. The places to which components will be mounted are typically plated, because untreated bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was coated with solder by hot air (solder) levelling (HASL aka HAL). The HASL finish prevents oxidation from the underlying copper, thereby guaranteeing a solderable surface. This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU, which restricts the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3% tin, 0.7% copper, 0.05% nickel, and a nominal of 60 ppm germanium. It is important to use solder compatible with both the PCB and the parts used. An example is ball grid array (BGA) using tin-lead solder balls for connections losing their balls on bare copper traces or using lead-free solder paste. Other platings used are organic solderability preservative (OSP), immersion silver (IAg), immersion tin (ISn), electroless nickel immersion gold (ENIG) coating, electroless nickel electroless palladium immersion gold (ENEPIG), and direct gold plating (over nickel). Edge connectors, placed along one edge of some boards, are often nickel-plated then gold-plated using ENIG. Another coating consideration is rapid diffusion of coating metal into tin solder. Tin forms intermetallics such as Cu6Sn5 and Ag3Cu that dissolve into the Tin liquidus or solidus (at 50 °C), stripping surface coating or leaving voids. Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias. Silver, zinc, and aluminum are known to grow whiskers under the influence of an electric field. Silver also grows conducting surface paths in the presence of halide and other ions, making it a poor choice for electronics use. Tin will grow "whiskers" due to tension in the plated surface. Tin-lead or solder plating also grows whiskers, only reduced by reducing the percentage of tin. Reflow to melt solder or tin plate to relieve surface stress lowers whisker incidence. Another coating issue is tin pest, the transformation of tin to a powdery allotrope at low temperature. === Solder resist application === Areas that should not be soldered may be covered with solder resist (solder mask). The solder mask is what gives PCBs their characteristic green color, although it is also available in several other colors, such as red, blue, purple, yellow, black and white. One of the most common solder resists used today is called "LPI" (liquid photoimageable solder mask). A photo-sensitive coating is applied to the surface of the PWB, then exposed to light through the solder mask image film, and finally developed where the unexposed areas are washed away. Dry film solder mask is similar to the dry film used to image the PWB for plating or etching. After being laminated to the PWB surface it is imaged and developed as LPI. Once but no longer commonly used, because of its low accuracy and resolution, is to screen print epoxy ink. In addition to repelling solder, solder resist also provides protection from the environment to the copper that would otherwise be exposed. === Legend / silkscreen === A legend (also known as silk or silkscreen) is often printed on one or both sides of the PCB. It contains the component designators, switch settings, test points and other indications helpful in assembling, testing, servicing, and sometimes using the circuit board. There are three methods to print the legend: Silkscreen printing epoxy ink was the established method, resulting in the alternative name. Liquid photo imaging is a more accurate method than screen printing. Ink jet printing is increasingly used. Ink jet can print variable data, unique to each PWB unit, such as text or a bar code with a serial number. === Bare-board test === Boards with no components installed are usually bare-board tested for "shorts" and "opens". This is called electrical test or PCB e-test. A short is a connection between two points that should not be connected. An open is a missing connection between points that should be connected. For high-volume production, a fixture such as a "bed of nails" in a rigid needle adapter makes contact with copper lands on the board. The fixture or adapter is a significant fixed cost and this method is only economical for high-volume or high-value production. For small or medium volume production flying probe testers are used where test probes are moved over the board by an XY drive to make contact with the copper lands. There is no need for a fixture and hence the fixed costs are much lower. The CAM system instructs the electrical tester to apply a voltage to each contact point as required and to check that this voltage appears on the appropriate contact points and only on these. === Assembly === In assembly the bare board is populated (or "stuffed") with electronic components to form a functional printed circuit assembly (PCA), sometimes called a "printed circuit board assembly" (PCBA). In through-hole technology, the component leads are inserted in holes surrounded by conductive pads; the holes keep the components in place. In surface-mount technology (SMT), the component is placed on the PCB so that the pins line up with the conductive pads or lands on the surfaces of the PCB; solder paste, which was previously applied to the pads, holds the components in place temporarily; if surface-mount components are applied to both sides of the board, the bottom-side components are glued to the board. In both through hole and surface mount, the components are then soldered; once cooled and solidified, the solder holds the components in place permanently and electrically connects them to the board. There are a variety of soldering techniques used to attach components to a PCB. High volume production is usually done with a pick-and-place machine and bulk wave soldering for through-hole parts or reflow ovens for SMT components and/or through-hole parts, but skilled technicians are able to hand-solder very tiny parts (for instance 0201 packages which are 0.02 in. by 0.01 in.) under a microscope, using tweezers and a fine-tip soldering iron, for small volume prototypes. Selective soldering may be used for delicate parts. Some SMT parts cannot be soldered by hand, such as BGA packages. All through-hole components can be hand soldered, making them favored for prototyping where size, weight, and the use of the exact components that would be used in high volume production are not concerns. Often, through-hole and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only in through-hole packages. Or, even if all components are available in through-hole packages, it might be desired to take advantage of the size, weight, and cost reductions obtainable by using some available surface-mount devices. Another reason to use both methods is that through-hole mounting can provide needed strength for components likely to endure physical stress (such as connectors that are frequently mated and demated or that connect to cables expected to impart substantial stress to the PCB-and-connector interface), while components that are expected to go untouched will take up less space using surface-mount techniques. For further comparison, see the SMT page. After the board has been populated it may be tested in a variety of ways: While the power is off, visual inspection, automated optical inspection. JEDEC guidelines for PCB component placement, soldering, and inspection are commonly used to maintain quality control in this stage of PCB manufacturing. While the power is off, analog signature analysis, power-off testing. While the power is on, in-circuit test, where physical measurements (for example, voltage) can be done. While the power is on, functional test, just checking if the PCB does what it had been designed to do. To facilitate these tests, PCBs may be designed with extra pads to make temporary connections. Sometimes these pads must be isolated with resistors. The in-circuit test may also exercise boundary scan test features of some components. In-circuit test systems may also be used to program nonvolatile memory components on the board. In boundary scan testing, test circuits integrated into various ICs on the board form temporary connections between the PCB traces to test that the ICs are mounted correctly. Boundary scan testing requires that all the ICs to be tested use a standard test configuration procedure, the most common one being the Joint Test Action Group (JTAG) standard. The JTAG test architecture provides a means to test interconnects between integrated circuits on a board without using physical test probes, by using circuitry in the ICs to employ the IC pins themselves as test probes. JTAG tool vendors provide various types of stimuli and sophisticated algorithms, not only to detect the failing nets, but also to isolate the faults to specific nets, devices, and pins. When boards fail the test, technicians may desolder and replace failed components, a task known as rework. === Protection and packaging === PCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane, acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered onto the PCB in a vacuum chamber. The chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficult. Many assembled PCBs are static sensitive, and therefore they must be placed in antistatic bags during transport. When handling these boards, the user must be grounded (earthed). Improper handling techniques might transmit an accumulated static charge through the board, damaging or destroying components. The damage might not immediately affect function but might lead to early failure later on, cause intermittent operating faults, or cause a narrowing of the range of environmental and electrical conditions under which the board functions properly. Even bare boards are sometimes static sensitive: traces have become so fine that it is possible to blow a trace (or change its characteristics) with a static discharge. This is especially true on non-traditional PCBs such as MCMs and microwave PCBs. === Cordwood construction === Cordwood construction can save significant space and was often used with wire-ended components in applications where space was at a premium (such as fuzes, missile guidance, and telemetry systems) and in high-speed computers, where short traces were important. In cordwood construction, axial-leaded components were mounted between two parallel planes. The name comes from the way axial-lead components (capacitors, resistors, coils, and diodes) are stacked in parallel rows and columns, like a stack of firewood. The components were either soldered together with jumper wire or they were connected to other components by thin nickel ribbon welded at right angles onto the component leads. To avoid shorting together different interconnection layers, thin insulating cards were placed between them. Perforations or holes in the cards allowed component leads to project through to the next interconnection layer. One disadvantage of this system was that special nickel-leaded components had to be used to allow reliable interconnecting welds to be made. Differential thermal expansion of the component could put pressure on the leads of the components and the PCB traces and cause mechanical damage (as was seen in several modules on the Apollo program). Additionally, components located in the interior are difficult to replace. Some versions of cordwood construction used soldered single-sided PCBs as the interconnection method (as pictured), allowing the use of normal-leaded components at the cost of being difficult to remove the boards or replace any component that is not at the edge. Before the advent of integrated circuits, this method allowed the highest possible component packing density; because of this, it was used by a number of computer vendors including Control Data Corporation. The cordwood method of construction was used only rarely once PCBs became widespread, mainly in aerospace or other extremely high-density electronics. == Types == === Breakout boards === A minimal PCB for a single component, used for prototyping, is called a breakout board. The purpose of a breakout board is to "break out" the leads of a component on separate terminals so that manual connections to them can be made easily. Breakout boards are especially used for surface-mount components or any components with fine lead pitch. Advanced PCBs may contain components embedded in the substrate, such as capacitors and integrated circuits, to reduce the amount of space taken up by components on the surface of the PCB while improving electrical characteristics. === Multiwire boards === Multiwire is a patented technique of interconnection which uses machine-routed insulated wires embedded in a non-conducting matrix (often plastic resin). It was used during the 1980s and 1990s. As of 2010, Multiwire was still available through Hitachi. Since it was quite easy to stack interconnections (wires) inside the embedding matrix, the approach allowed designers to forget completely about the routing of wires (usually a time-consuming operation of PCB design): Anywhere the designer needs a connection, the machine will draw a wire in a straight line from one location/pin to another. This led to very short design times (no complex algorithms to use even for high density designs) as well as reduced crosstalk (which is worse when wires run parallel to each other—which almost never happens in Multiwire), though the cost is too high to compete with cheaper PCB technologies when large quantities are needed. Corrections can be made to a Multiwire board layout more easily than to a PCB layout. == Uses == Printed circuit boards have been used as an alternative to their typical use for electronic and biomedical engineering thanks to the versatility of their layers, especially the copper layer. PCB layers have been used to fabricate sensors, such as capacitive pressure sensors and accelerometers, actuators such as microvalves and microheaters, as well as platforms of sensors and actuators for Lab-on-a-chip (LoC), for example to perform polymerase chain reaction (PCR), and fuel cells, to name a few. == Repair == Manufacturers may not support component-level repair of printed circuit boards because of the relatively low cost to replace compared with the time and cost of troubleshooting to a component level. In board-level repair, the technician identifies the board (PCA) on which the fault resides and replaces it. This shift is economically efficient from a manufacturer's point of view but is also materially wasteful, as a circuit board with hundreds of functional components may be discarded and replaced due to the failure of one minor and inexpensive part, such as a resistor or capacitor. This practice is a significant contributor to the problem of e-waste. == Legislation == In many countries (including all European Single Market participants, the United Kingdom, Turkey, and China), legislation restricts the use of lead, cadmium and mercury in electrical equipment. PCBs sold in such countries must therefore use lead-free manufacturing processes and lead-free solder, and attached components must themselves be compliant. Safety Standard UL 796 covers component safety requirements for printed wiring boards for use as components in devices or appliances. Testing analyzes characteristics such as flammability, maximum operating temperature, electrical tracking, heat deflection, and direct support of live electrical parts. == See also == Breadboard Certified interconnect designer - qualification for PCB designers Occam process - solder-free circuit board manufacture method BT-Epoxy - resin used in PCBs == References == == Further reading == Tavernier, Karel (September 2015). "PCB Fabrication Data - Design to Fabrication Data Transfer" (PDF). V6. Archived (PDF) from the original on 2022-03-08. Retrieved 2022-05-09. (45 pages) Colotti, James (2022). "Analog, RF and EMC Considerations in Printed Wiring Board (PWB) Design" (PDF). Revision 5. IEEE, Long Island Section. Archived (PDF) from the original on 2022-05-08. Retrieved 2022-05-09. (81 pages) Media related to Printed circuit boards at Wikimedia Commons

A printed circuit board (PCB), also called printed wiring board (PWB), is a medium used to connect or "wire" components to one another in a circuit. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers in the shape designed to accept the component's terminals, generally by means of soldering, to both electrically connect and mechanically fasten them to it. Another manufacturing process adds vias, plated-through holes that allow interconnections between layers. Printed circuit boards are used in nearly all electronic products. Alternatives to PCBs include wire wrap and point-to-point construction, both once popular but now rarely used. PCBs require additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Electronic design automation software is available to do much of the work of layout. Mass-producing circuits with PCBs is cheaper and faster than with other wiring methods, as components are mounted and wired in one operation. Large numbers of PCBs can be fabricated at the same time, and the layout has to be done only once. PCBs can also be made manually in small quantities, with reduced benefits. PCBs can be single-sided (one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multi-layer (outer and inner layers of copper, alternating with layers of substrate). Multi-layer PCBs allow for much higher component density, because circuit traces on the inner layers would otherwise take up surface space between components. The rise in popularity of multilayer PCBs with more than two, and especially with more than four, copper planes was concurrent with the adoption of surface mount technology. However, multilayer PCBs make repair, analysis, and field modification of circuits much more difficult and usually impractical. The world market for bare PCBs exceeded $60.2 billion in 2014 and is estimated to reach $79 billion by 2024.

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exhibition game

Freundschaftsspiel (wiktionary)

Freundschaft (“friendship”) +‎ Spiel (“match”) Freundschaftsspiel n (strong, genitive Freundschaftsspieles or Freundschaftsspiels, plural Freundschaftsspiele) friendly match “Freundschaftsspiel” in Duden online

16

exhibition game

exhibition game (wiktionary)

exhibition game (plural exhibition games) (sports) A practice game which does not count on a team's record.

17

exhibition game

Exhibition game (wikipedia)

An exhibition game (also known as a friendly, a scrimmage, a demonstration, a pre-season game, a warmup match, or a preparation match, depending at least in part on the sport) is a sporting event whose prize money and impact on the player's or the team's rankings is either zero or otherwise greatly reduced. Exhibition games often serve as "warm-up matches", particularly in many team sports where these games help coaches and managers select and condition players, before the competitive matches of a league season or tournament. If the players usually play in different teams in other leagues, exhibition games offer an opportunity for the players to learn to work with each other. The games can be held between separate teams or between parts of the same team. An exhibition game may also be used to settle a challenge, to provide professional entertainment, to promote the sport, to commemorate an anniversary or a famous player, or to raise money for charities. Several sports leagues hold all-star games to showcase their best players against each other, while other exhibitions games may pit participants from two different leagues or countries to unofficially determine who would be the best in the world. International competitions like the Olympic Games may also hold exhibition games as part of a demonstration sport. == Association football == In the early days of association football, friendlies were the most common type of match. However, with the development of The Football League in England in 1888, league and cup tournaments became the primary methods of competition. The significance of friendly matches thus declined since the 19th century: by 2000, national leagues were established in almost every country throughout the world, with local or regional leagues for lower-level teams. === Club football === Since the introduction of league football, most club sides play a number of friendlies before the start of each season (called pre-season friendlies). Friendly football matches are considered to be non-competitive and are mostly used to "warm up" players for a new season/competitive match. Some rules may be changed or experimented with, such as unlimited substitutions (which allow teams to play less experienced players). Frequently such games take place between a large club and nearby smaller clubs, such as those between Newcastle United and Gateshead, or on a large club on an international tour against local opponents. Since the 2000s, friendlies played in the United States have become increasingly lucrative for European teams. Although most friendlies are simply one-off matches arranged between the clubs in which a certain amount is paid by the challenger club to the incumbent club, some teams do compete in short tournaments, such as the Emirates Cup, Teresa Herrera Trophy, International Champions Cup and the Amsterdam Tournament. Although these events may involve sponsorship deals, a trophy, and television broadcasts, there is little prestige attached to them. In addition, club teams may tour other continents as part of global branding campaigns. === International football === International teams also play friendlies, generally in preparation for the qualifying or final stages of major tournaments. This is essential, since national squads generally have much less time together in which to prepare. The biggest difference between friendlies at the club and international levels is that international friendlies mostly take place during club league seasons, not between them. This has on occasion led to disagreement between national associations and clubs as to the availability of players, who could become injured or fatigued in a friendly. International friendlies give team managers the opportunity to experiment with team selection and tactics before the tournament proper, and also allow them to assess the abilities of players they may potentially select for the tournament squad. Players can be booked in international friendlies, and can be suspended from future international matches based on red cards or accumulated yellows in a specified period. Caps and goals scored also count towards a player's career records. The results can play a part in affecting the country's FIFA ranking. In 2004, FIFA ruled that substitutions by a team be limited to six per match in international friendlies in response to criticism that such matches were becoming increasingly farcical with managers making as many as 11 substitutions per match. An international match loses its official status if this regulation is breached. Matches in multinational football tournaments such as the King's Cup, the Kirin Cup, and the China Cup are usually considered international friendlies by FIFA. === Fundraising game === In the UK and Ireland, "exhibition match" and "friendly match" refer to two different types of games. The types described above as friendlies are not termed exhibition matches, all-star matches such as those held in the US Major League Soccer, Japan's J.League or South Korea's K League are called exhibition matches rather than friendly matches. A one-off match for charitable fundraising, usually involving one or two all-star teams, or a match held in honor of a player for contribution to their club, may also be described as exhibition matches but they are normally referred to as charity matches (Soccer Aid, Team UNICEF etc.) and testimonial matches respectively. === Training game === A training game is generally a non-competitive football match played between two sides usually as part of a training exercise or to give players match practice. Managers may also use bounce games as an opportunity to observe a player in action before offering a contract. Usually these games are played on a training ground rather than in a stadium with no spectators in attendance. == Bandy == Before the establishment of the Bandy World Championship in 1957, annually held friendly games were the main events for national teams of the sport. International friendlies are still often held. == Boxing == Exhibition fights were once common in boxing. Jack Dempsey fought many exhibition bouts after retiring. Joe Louis fought a charity fight on his rematch with Buddy Baer, but this was not considered an exhibition as it was for Louis' world Heavyweight title, and as a championship fight, it counted on both boxers' records. Muhammad Ali fought many exhibitions, including one with Lyle Alzado. In more modern times, Mike Tyson, Julio César Chávez, Jorge Castro, and Floyd Mayweather Jr. have been involved in exhibition fights. Although not fought for profit, amateur bouts (usually) and sparring sessions are not considered to be exhibition fights. On 25 August 2018, YouTubers Logan Paul and KSI had an exhibition match that ended in a draw. On 28 November 2020, Mike Tyson and Roy Jones Jr. had a fight that ended in a draw. == Ice hockey == Prior to the 1917–18 NHL season, an exhibition game was played on 15 December, between the Montreal Canadiens and the Montreal Wanderers. The game was played as a benefit to aid victims of the Halifax explosion. Under the 1995–2004 National Hockey League collective bargaining agreement, teams were limited to nine preseason games. From 1975 to 1991, NHL teams sometimes played exhibition games against teams from the Soviet Union in the Super Series, and in 1978, played against World Hockey Association teams also in preseason training. Like the NFL, the NHL sometimes schedules exhibition games for cities without their own NHL teams, often at a club's minor league affiliate (e.g. Carolina Hurricanes games at Time Warner Cable Arena in Charlotte, North Carolina, home of their AHL affiliate the Charlotte Checkers; Los Angeles Kings games at Citizens Business Bank Arena in Ontario, California, home of their AHL affiliate the Ontario Reign; Montreal Canadiens games at Colisée Pepsi in Quebec City, which has no pro hockey but used to have an NHL team until 1995; Washington Capitals at 1st Mariner Arena in the Baltimore Hockey Classic; Buffalo Sabres at Pegula Ice Arena on the campus of owner Terrence Pegula's alma mater Penn State University; various Western Canada teams at Credit Union Centre in Saskatoon, a potential NHL expansion venue; and the St. Louis Blues in Kansas City, Missouri at T-Mobile Center, also a potential expansion venue that is currently considered part of the Blues' television market). Before the Vegas Golden Knights entered the NHL in 2017, the Kings would traditionally play an annual game known as Frozen Fury in Las Vegas in a partnership with the MGM Grand Las Vegas. The game is played today at Vivint Arena in Salt Lake City, Utah. Today, all teams must play six, seven, or eight preseason games. Each preseason game must have at least eight veterans dressed, except during the World Cup of Hockey. In the 1994–95 season and the 2012–13 season, no preseason games were played due to lockouts. Since the 2000s, some preseason games have been played in Europe against European teams, as part of the NHL Challenge and NHL Premiere series. In addition to the standard preseason, there also exist prospect tournaments such as the Vancouver Canucks' YoungStars tournament and the Detroit Red Wings' training camp, in which NHL teams' younger prospects face off against each other under their parent club's banner. In 1992, goaltender Manon Rhéaume played in a preseason game for the Tampa Bay Lightning, becoming the first woman to suit up for an all-male pro sports team in North America. The Flying Fathers, a Canadian group of Catholic priests, regularly toured North America playing exhibition hockey games for charity. One of the organization's founders, Les Costello, was a onetime NHL player who was ordained as a priest after retiring from professional hockey. Another prominent exhibition hockey team is the Buffalo Sabres Alumni Hockey Team, which is composed almost entirely of retired NHL players, the majority of whom (as the name suggests) played at least a portion of their career for the Buffalo Sabres. American college hockey teams occasionally play exhibition games against Canadian college teams as well as against USA or Canadian national teams. (In men's hockey, the senior national teams are selected from NHL and other pro players, and college teams would be overmatched against those teams even if they were allowed to play them. However, the national under-18 teams are made up of amateurs, allowing college squads to play them.) == Baseball == The Major League Baseball's preseason is also known as spring training. All MLB teams maintain a spring-training base in Arizona or Florida. The teams in Arizona make up the Cactus League, while the teams in Florida play in the Grapefruit League. Each team plays about 30 preseason games against other MLB teams. They may also play exhibitions against a local college team or a minor-league team from their farm system. Some days feature the team playing two games with two different rosters evenly divided up, which are known as "split-squad" games. Several MLB teams used to play regular exhibition games during the year against nearby teams in the other major league, but regular-season interleague play has made such games unnecessary. The two Canadian MLB teams, the Toronto Blue Jays of the American League and the Montreal Expos of the National League, met annually to contest the Pearson Cup; this tradition ended when the Expos moved to Washington DC for the 2005 season. Similarly, the New York Yankees played in the Mayor's Trophy Game against various local rivals from 1946 to 1983. It also used to be commonplace to have a team play an exhibition against Minor League affiliates during the regular season, but worries of injuries to players, along with travel issues, have made this very rare. Exhibitions between inter-city teams in different leagues, like Chicago's Crosstown Classic and New York's Subway Series which used to be played solely as exhibitions for bragging rights are now blended into interleague play. The annual MLB All-Star Game, played in July between players from AL teams and players from NL teams, had long been considered an exhibition match, though between 2003 and 2016 this status was questioned because the league whose team won the All-Star game has been awarded home field advantage for the upcoming World Series (prior to 2003 the leagues alternated which one of them had home field advantage; starting in 2017 the team with the better regular season record would be given home field advantage). Another exhibition game, the Hall of Fame Game/Classic which was played in Cooperstown, New York on the weekend of inductions to the Baseball Hall of Fame, was also ended in 2008 due to interleague play and teams playing only substitutes. == Basketball == === Professional basketball === National Basketball Association teams usually play eight preseason games per year, with the number rarely being lower than seven. Today, NBA teams almost always play each other in the preseason but often at neutral sites within their market areas in order to allow those who can not usually make a trip to a home team's arena during the regular season to see a game close to home; for instance, the Minnesota Timberwolves will play games in arenas in North and South Dakota, while the Phoenix Suns schedule one exhibition game outdoors at Indian Wells Tennis Garden in Indian Wells, California, yearly, the only such instance an NBA game takes place in an outdoor venue. Exhibition games have also been held on occasion outside the US and Canada. However, from 1971 to 1975, NBA teams played preseason exhibitions against American Basketball Association teams with the ABA winning the series 80 to 75 games. In the early days of the NBA, league clubs sometimes challenged the legendary barnstorming Harlem Globetrotters, with mixed success. The Minneapolis Lakers beat the Globetrotters seven games to one. The NBA has played preseason games in Europe and Asia. Beginning in 2015, the league has scheduled NBA Africa Games with players of direct African descent against players from the rest of the league; the NBA has also played against teams in Australia's National Basketball League. In the 2006 and 2007 seasons, the NBA and the primary European club competition, the Euroleague, conducted a preseason tournament featuring two NBA teams and the finalists from that year's Euroleague. In the 1998–99 and 2011–12 seasons, teams were limited to only two preseason games due to lockouts. The annual NBA All-Star Game is an exhibition game. Women's National Basketball Association teams play up to three preseasons games per year. WNBA teams will play each other and will also play women's national basketball teams. Most years, the WNBA also stages an All-Star Game, but this game is canceled if pre-empted by major international competitions such as the Olympic Games. === College basketball === Traditionally, major college basketball teams began their seasons with a few exhibition games. They played traveling teams made up of former college players on teams such as Athletes in Action or a team sponsored by Marathon Petroleum. On occasion before 1992, when FIBA allowed professional players on foreign national teams, colleges played those teams in exhibitions. However, in 2003, the National Collegiate Athletic Association banned games with non-college teams. Some teams have begun scheduling exhibition games against teams in NCAA Division II, NCAA Division III and the NAIA, or even against colleges and universities located in Canada. Major college basketball teams still travel to other countries during the summer to play in exhibition games, although a college team is allowed only one foreign tour every four years and a maximum of ten games in each tour. == American football == === Professional football === The National Football League teams play three preseason games a year, at least one of which is played at home, with the exception of two teams each year who play a fourth game, the Pro Football Hall of Fame Game (previously before the 2021 season expansion, two home and two away games). These exhibition games, most of which are held in the month of August, are played for the purpose of helping coaches narrow down the roster from the offseason limit of 90 players to the regular-season limit of 53 players. While the scheduling formula is not as rigid for preseason games as they are for the regular season, there are numerous restrictions and traditions that limit the choices of preseason opponents; teams are also restricted on what days and times they can play these games. Split-squad games, a practice common in baseball and hockey, where a team that is scheduled to play two games on the same day splits their team into two squads, are prohibited. The NFL has played exhibition games in Europe, Japan, Canada, Australia (including the American Bowl in 1999) and Mexico to spread the league's popularity (a game of this type was proposed for China but, due to financial and logistical problems, was eventually canceled). The league has tacitly forbidden the playing of non-league opponents, with the last interleague game having come in 1972 and the last game against a team other than an NFL team (the all-NFL rookie College All-Stars) was held in 1976. Exhibition games are quite unpopular with many fans, who resent having to pay regular-season prices for two home exhibition games as part of a season-ticket package. Numerous lawsuits have been brought by fans and classes of fans against the NFL or its member teams regarding this practice, but none have been successful in halting it. The Pro Bowl, traditionally played after the end of the NFL season (since 2011 played the week prior to the Super Bowl), is also considered an exhibition game. The Arena Football League briefly had a two-game exhibition season in the early 2000s, a practice that ended in 2003 with a new television contract. Exhibition games outside of a structured season are relatively common among indoor American football leagues; because teams switch leagues frequently at that level of play, it is not uncommon to see some of the smaller leagues schedule exhibition games against teams that are from another league, about to join the league as a probational franchise, or a semi-pro outdoor team to fill holes in a schedule. === College and high school football === Many college football teams, particularly larger organizations, play a public intramural exhibition game in the spring mainly to promote the team and give new recruits an early chance at public game action. Many of these intramural games are nationally televised, though not to the same level of prominence as intercollegiate play. In college sports the commonly used term for the major scrimmage at the end of spring practice is the "Spring Game." True exhibition games between opposing colleges at the highest level do not exist in college football; due to the importance of opinion polling in the top level of college football, even exhibition games would not truly be exhibitions because they could influence the opinions of those polled. Intramural games are possible because a team playing against itself leaves little ability for poll participants to make judgments, and at levels below the Football Bowl Subdivision (FBS), championships are decided by objective formulas and thus those teams can play non-league games without affecting their playoff hopes. High school football teams frequently participate in controlled scrimmages with other teams during preseason practice, but full exhibition games are rare because of league rules and concerns about finances, travel and player injuries, along with enrollments not being registered until the early part of August in most school districts under the traditional September–June academic term. Some states hold preseason events known as "jamborees" in which several pairs of high school football squads take turns playing one half (usually 24 minutes of game time) to give players some experience before the first official game. Another high school football exhibition contest is the all-star game, which usually brings together top players from a region. These games are typically played by graduating seniors after the regular season or in the summer. Many of these games, which include the U.S. Army All-American Bowl and Under Armour All-America Game, are used as showcases for players to be seen by colleges and increase their college recruiting profile, or for athletes to confirm their choice and sign their National Letter of Intent outside of National Signing Day. === Teams outside North America === Outside North America, teams will sometimes organize exhibition games as part of their pre season preparations – German Football League teams for example often schedule games against second or third tier opponents ahead of their regular season. Exhibition games are also sometimes scheduled between teams from different countries which would otherwise never play each other – including on occasion between non-North American teams and North American college teams. As a result of the COVID-19 pandemic leading to the cancellation of regular league play in many places, some teams scheduled exhibition games instead, including the Dresden Monarchs hosting the Wroclaw Panthers on September 20, 2020. == Canadian football == Teams in the Canadian Football League play two exhibition games each year, in June. Exhibition games in the CFL have taken on great importance to coaching staff and players alike in that they are used as a final stage of training camp and regular season rosters are finalized after the exhibition games, which are generally referred to as "pre-season" play. == Rugby union == During the amateur era, there was only a limited number of rugby union competitions between national teams. Therefore, matches between national teams are never considered "exhibitions" or "friendlies", as they always have Test match status. National teams sometimes play exhibition matches versus invitational teams like the Barbarian F.C. and Barbarian Rugby Club. Also, rugby union clubs sometimes play preseason matches. == Australian rules football == Australian rules football has been introduced to a wide range of places around Australia and the world since the code originated in Victoria in 1859. Much of this expansion can be directly attributed to exhibition matches by the major leagues in regions and countries where the code has been played as a demonstration sport. == Auto racing == Various auto racing organizations hold non-championship exhibition events; these events usually award no championship points to participants, but they do offer prize money to participants. The NASCAR Cup Series holds two exhibition events annually – the Busch Clash, held at Los Angeles Memorial Coliseum at the start of the season, and the All-Star Race, held at North Wilkesboro Speedway midway through the season. Both events carry a hefty purse of over US$1,000,000. NASCAR has also held exhibition races at Suzuka Circuit and Twin Ring Motegi in Japan and Calder Park Thunderdome in Australia. Other historical examples of non-championship races include the Marlboro Challenge in IndyCar racing and the TOCA Touring Car Shootout in the British Touring Car Championship. Until the mid-1980s there were also a significant number of non-championship Formula One races. The National Hot Rod Association Pro Stock teams will have a preseason drag meet held before the traditional start in Pomona. The Pro Stock Showdown is a preseason drag meet held for the Pro Stock teams held at The Strip at Las Vegas Motor Speedway. == Sumo == In sumo wrestling, official tournaments (honbasho) are held six times per year, in the cities of Tokyo, Osaka, Nagoya, and Fukuoka. In between the tournaments, regional tours known as jungyō (巡業) are undertaken to bring sumo wrestling to more regions of Japan. In addition to exhibition bouts, there are "demonstrations of hairdressing, comedy sumo and sumo singing", as well as opportunities for fans to meet with wrestlers and for sumo stables to find new recruits. == See also == Criterium Sparring == References == == External links == All-Time ABA vs. NBA Exhibition Game Results Remember the ABA – article about NBA vs. ABA exhibitions College Basketball Exhibitions: No Longer Open Season CollegeHoopsNet, 16 November 2004 – article about the 2003 NCAA ruling

An exhibition game (also known as a friendly, a scrimmage, a demonstration, a pre-season game, a warmup match, or a preparation match, depending at least in part on the sport) is a sporting event whose prize money and impact on the player's or the team's rankings is either zero or otherwise greatly reduced. Exhibition games often serve as "warm-up matches", particularly in many team sports where these games help coaches and managers select and condition players, before the competitive matches of a league season or tournament. If the players usually play in different teams in other leagues, exhibition games offer an opportunity for the players to learn to work with each other. The games can be held between separate teams or between parts of the same team. An exhibition game may also be used to settle a challenge, to provide professional entertainment, to promote the sport, to commemorate an anniversary or a famous player, or to raise money for charities. Several sports leagues hold all-star games to showcase their best players against each other, while other exhibitions games may pit participants from two different leagues or countries to unofficially determine who would be the best in the world. International competitions like the Olympic Games may also hold exhibition games as part of a demonstration sport.

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light bulb

Glühbirne (wiktionary)

glühen (“to glow”) +‎ Birne (“pear”), due to the pear-like shape of (older) light bulbs. IPA(key): /ˈɡlyːˌbɪʁnə/, [-ˌbɪʁnə], [-ˌbɪɐ̯nə] Hyphenation: Glüh‧bir‧ne Glühbirne f (genitive Glühbirne, plural Glühbirnen) light bulb (lamp consisting of a glass bulb with a heated filament, or similar lighting article) “Glühbirne” in Duden online “Glühbirne” in Digitales Wörterbuch der deutschen Sprache

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light bulb

light bulb (wiktionary)

light-bulb, lightbulb light +‎ bulb First attested in 1885. IPA(key): /ˈlaɪtˌbʌlb/ light bulb (plural light bulbs) An evacuated glass bulb containing a metal filament which is heated by electrical resistance to produce light. Synonyms: bulb, glow-lamp, incandescent lamp, (Australia) light globe (by extension) An article that resembles such a bulb and converts electricity to light by any process. (figuratively) Used in reference to the sudden arrival of a realization, an inspiration, an idea, or the like. light bulb joke light-bulb moment electric light on Wikipedia.Wikipedia

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light bulb

Light Bulb (Abbott Elementary) (wikipedia)

"Light Bulb" is the second episode of the American sitcom television series Abbott Elementary. It was written by series creator and star Quinta Brunson, and was directed by Randall Einhorn. It premiered on the American Broadcasting Company (ABC) in the United States on January 4, 2022. The episode follows Janine (Quinta Brunson), who attempts to fix a flickering light without the help of the school or electricians, and Gregory (Tyler James Williams) who must confront a parent of his class for bringing her son into school late. The episode sees the first appearance of recurring characters, Tariq Temple and Amber Williams. The episode also sees a short cameo from Philadelphia broadcaster Jim Gardner, who appears in the cold open and is beloved by the staff of Abbott. == Plot == Janine arrives at school with her boyfriend, Tariq (Zack Fox). She finds a student who does not want to walk down the hallway because of a flickering light. Mr. Johnson (William Stanford Davis) tells her that it is above his paygrade to fix it and that they will have to wait for an electrician to get the lights fixed; because of this, she decides to fix the light herself. In Gregory's class, a student arrives with his mother an hour late, and he tries but fails to call the attention of the mother and only manages to tell her that school starts earlier than when they arrived, to which she barely acknowledges. Barbara tells him that he simply needs to talk to the student's mother. Janine finds a ladder and tries to fix the lights herself, but instead causes a partial power outage in the school. Barbara coaches Gregory into confronting Amber about her son's tardiness. He tells her that her son could fall behind and retake the grade, and she promises him that her son will be at school on time. In the electrical room, Janine fiddles with the circuit breakers in the panel box with the help of Jacob which causes all the remaining power to go out, including the air conditioning. Barbara and Melissa confront Janine after the outage; shortly before she faints due to having not eaten any food. Janine wakes up in the nurse's office. Janine finds that everybody else is outside due to the outage and the heat. Janine expresses her disappointment that after trying so hard to fix the issue with the lights, she instead managed to make things worse. Janine tries calling Tariq but gets his voicemail. Shortly after, Gregory arrives and the two decide to grab dinner. Jacob sees the two leaving and invites himself to join. Just as they leave, they find that Mr. Johnson has fixed the lights. == Reception == Upon its initial broadcast on ABC, "Light Bulb" received a total of 3.45 million viewers. Compared to the first episode, the second episode increased its viewership by 5.6 million viewers to 9 million after 35 days. Following DVR viewership totals, the total viewership within the first 35 days of its airing was 4.27 million. The episode has the highest viewership in the series overall. The episode was included as part of the show's submission for the Outstanding Comedy Series award. The episode airs following its midseason entry in the 2021–22 television season; and following a winter break. Filming for the episode took place between August 16, and November 5, 2021, in Los Angeles, California. Like other episodes, interior scenes are filmed at Warner Bros. Studios, Burbank in Burbank, California, with exterior shots of the series being filmed in front of Vermont Elementary School in Los Angeles. === Critical response === Janelle Ureta of Tell-Tale TV complemented the series by stating that; ""Light Bulb," is more heart warming than hilarious, but given the state of the world at the moment, that is perfectly excusable. The funniest bits come from little, often silly, very specific, moments." However, Ureta critiqued the episodes use of slow-humor, by stating; "However, to establish itself as a top-tier comedy, the new ABC series needs to have funny jokes with a larger reach. Janine’s persistent idealism and Ava’s persistent inappropriate flirting aren't enough. On “Light Bulb," they make us want to yell at the screen to move-it-along. Ava's doomsday bunker is far more interesting and entertaining." == Notes == == References ==

"Light Bulb" is the second episode of the American sitcom television series Abbott Elementary. It was written by series creator and star Quinta Brunson, and was directed by Randall Einhorn. It premiered on the American Broadcasting Company (ABC) in the United States on January 4, 2022. The episode follows Janine (Quinta Brunson), who attempts to fix a flickering light without the help of the school or electricians, and Gregory (Tyler James Williams) who must confront a parent of his class for bringing her son into school late. The episode sees the first appearance of recurring characters, Tariq Temple and Amber Williams. The episode also sees a short cameo from Philadelphia broadcaster Jim Gardner, who appears in the cold open and is beloved by the staff of Abbott.

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light bulb

Electric light (wikipedia)

An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic which secures the lamp in the socket of a light fixture, which is often called a "lamp" as well. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet mount. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, such as fluorescent lamps, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery-powered light is often reserved for when and where stationary lights fail, often in the form of flashlights or electric lanterns, as well as in vehicles. == History == Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. In 1799–1800, Alessandro Volta created the voltaic pile, the first electric battery. Current from these batteries could heat copper wire to incandescence. Vasily Vladimirovich Petrov developed the first persistent electric arc in 1802, and English chemist Humphry Davy gave a practical demonstration of an arc light in 1806. It took more than a century of continuous and incremental improvement, including numerous designs, patents, and resulting intellectual property disputes, to get from these early experiments to commercially produced incandescent light bulbs in the 1920s. In 1840, Warren de la Rue enclosed a platinum coil in a vacuum tube and passed an electric current through it, thus creating one of the world's first electric light bulbs. The design was based on the concept that the high melting point of platinum would allow it to operate at high temperatures and that the evacuated chamber would contain fewer gas molecules to react with the platinum, improving its longevity. Although it was an efficient design, the cost of the platinum made it impractical for commercial use. William Greener, an English inventor, made significant contributions to early electric lighting with his lamp in 1846 (patent specification 11076), laying the groundwork for future innovations such as those by Thomas Edison. The late 1870s and 1880s were marked by intense competition and innovation, with inventors like Joseph Swan in the UK and Thomas Edison in the US independently developing functional incandescent lamps. Swan's bulbs, based on designs by William Staite, were successful, but the filaments were too thick. Edison worked to create bulbs with thinner filaments, leading to a better design. The rivalry between Swan and Edison eventually led to a merger, forming the Edison and Swan Electric Light Company. By the early twentieth century these had completely replaced arc lamps. The turn of the century saw further improvements in bulb longevity and efficiency, notably with the introduction of the tungsten filament by William D. Coolidge, who applied for a patent in 1912. This innovation became a standard for incandescent bulbs for many years. In 1910, Georges Claude introduced the first neon light, paving the way for neon signs which would become ubiquitous in advertising. In 1934, Arthur Compton, a renowned physicist and GE consultant, reported to the GE lamp department on successful experiments with fluorescent lighting at General Electric Co., Ltd. in Great Britain (unrelated to General Electric in the United States). Stimulated by this report, and with all of the key elements available, a team led by George E. Inman built a prototype fluorescent lamp in 1934 at General Electric’s Nela Park (Ohio) engineering laboratory. This was not a trivial exercise; as noted by Arthur A. Bright, "A great deal of experimentation had to be done on lamp sizes and shapes, cathode construction, gas pressures of both argon and mercury vapor, colors of fluorescent powders, methods of attaching them to the inside of the tube, and other details of the lamp and its auxiliaries before the new device was ready for the public." The first practical LED arrived in 1962. === U.S. transition to LED bulbs === In the United States, incandescent light bulbs including halogen bulbs stopped being sold as of August 1, 2023, because they do not meet minimum lumens per watt performance metrics established by the U.S. Department of Energy. Compact fluorescent bulbs are also banned despite their lumens per watt performance, because of their toxic mercury that can be released into the home if broken and widespread problems with proper disposal of mercury-containing bulbs. == Types == === Incandescent === In its modern form, the incandescent light bulb consists of a coiled filament of tungsten sealed in a globular glass chamber, either a vacuum or full of an inert gas such as argon. When an electric current is connected, the tungsten is heated to 2,000 to 3,300 K (1,730 to 3,030 °C; 3,140 to 5,480 °F) and glows, emitting light that approximates a continuous spectrum. Incandescent bulbs are highly inefficient, in that just 2–5% of the energy consumed is emitted as visible, usable light. The remaining 95% is lost as heat. In warmer climates, the emitted heat must then be removed, putting additional pressure on ventilation or air conditioning systems. In colder weather, the heat byproduct has some value, and has been successfully harnessed for warming in devices such as heat lamps. Incandescent bulbs are nonetheless being phased out in favor of technologies like CFLs and LED bulbs in many countries due to their low energy efficiency. The European Commission estimated in 2012 that a complete ban on incandescent bulbs would contribute 5 to 10 billion euros to the economy and save 15 billion metric tonnes of carbon dioxide emissions. === Halogen === Halogen lamps are usually much smaller than standard incandescent lamps, because for successful operation a bulb temperature over 200 °C is generally necessary. For this reason, most have a bulb of fused silica (quartz) or aluminosilicate glass. This is often sealed inside an additional layer of glass. The outer glass is a safety precaution, to reduce ultraviolet emission and to contain hot glass shards should the inner envelope explode during operation. Oily residue from fingerprints may cause a hot quartz envelope to shatter due to excessive heat buildup at the contamination site. The risk of burns or fire is also greater with bare bulbs, leading to their prohibition in some places, unless enclosed by the luminaire. Those designed for 12- or 24-volt operation have compact filaments, useful for good optical control. Also, they have higher efficacies (lumens per watt) and longer lives than non-halogen types. The light output remains almost constant throughout their life. === Fluorescent === Fluorescent lamps consist of a glass tube that contains mercury vapour or argon under low pressure. Electricity flowing through the tube causes the gases to give off ultraviolet energy. The inside of the tubes are coated with phosphors that give off visible light when struck by ultraviolet photons. They have much higher efficiency than incandescent lamps. For the same amount of light generated, they typically use around one-quarter to one-third the power of an incandescent. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. Fluorescent lamp fixtures are more costly than incandescent lamps, because they require a ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost. Compact fluorescent lamps are available in the same popular sizes as incandescent lamps and are used as an energy-saving alternative in homes. Because they contain mercury, many fluorescent lamps are classified as hazardous waste. The United States Environmental Protection Agency recommends that fluorescent lamps be segregated from general waste for recycling or safe disposal, and some jurisdictions require recycling of them. === LED === The solid-state light-emitting diode (LED) has been popular as an indicator light in consumer electronics and professional audio gear since the 1970s. In the 2000s, efficacy and output have risen to the point where LEDs are now being used in lighting applications such as car headlights and brake lights, in flashlights and bicycle lights, as well as in decorative applications, such as holiday lighting. Indicator LEDs are known for their extremely long life, up to 100,000 hours, but lighting LEDs are operated much less conservatively, and consequently have shorter lives. LED technology is useful for lighting designers, because of its low power consumption, low heat generation, instantaneous on/off control, and in the case of single color LEDs, continuity of color throughout the life of the diode and relatively low cost of manufacture. LED lifetime depends strongly on the temperature of the diode. Operating an LED lamp in conditions that increase the internal temperature can greatly shorten the lamp's life. Some lasers have been adapted as an alternative to LEDs to provide highly focused illumination. === Carbon arc === Carbon arc lamps consist of two carbon rod electrodes in open air, supplied by a current-limiting ballast. The electric arc is struck by touching the rod tips then separating them. The ensuing arc produces a white-hot plasma between the rod tips. These lamps have higher efficacy than filament lamps, but the carbon rods are short-lived and require constant adjustment in use, as the intense heat of the arc erodes them. The lamps produce significant ultraviolet output, they require ventilation when used indoors, and due to their intensity they need protection from direct sight. Invented by Humphry Davy around 1805, the carbon arc was the first practical electric light. It was used commercially beginning in the 1870s for large building and street lighting until it was superseded in the early 20th century by the incandescent light. Carbon arc lamps operate at high power and produce high intensity white light. They also are a point source of light. They remained in use in limited applications that required these properties, such as movie projectors, stage lighting, and searchlights, until after World War II. === Discharge === A discharge lamp has a glass or silica envelope containing two metal electrodes separated by a gas. Gases used include, neon, argon, xenon, sodium, metal halides, and mercury. The core operating principle is much the same as the carbon arc lamp, but the term "arc lamp" normally refers to carbon arc lamps, with more modern types of gas discharge lamp normally called discharge lamps. With some discharge lamps, very high voltage is used to strike the arc. This requires an electrical circuit called an igniter, which is part of the electrical ballast circuitry. After the arc is struck, the internal resistance of the lamp drops to a low level, and the ballast limits the current to the operating current. Without a ballast, excess current would flow, causing rapid destruction of the lamp. Some lamp types contain a small amount of neon, which permits striking at normal running voltage with no external ignition circuitry. Low-pressure sodium lamps operate this way. The simplest ballasts are just an inductor, and are chosen where cost is the deciding factor, such as street lighting. More advanced electronic ballasts may be designed to maintain constant light output over the life of the lamp, may drive the lamp with a square wave to maintain completely flicker-free output, and shut down in the event of certain faults. The most efficient source of electric light is the low-pressure sodium lamp. It produces, for all practical purposes, a monochromatic orange-yellow light, which gives a similarly monochromatic perception of any illuminated scene. For this reason, it is generally reserved for outdoor public lighting applications. Low-pressure sodium lights are favoured for public lighting by astronomers, since the light pollution that they generate can be easily filtered, contrary to broadband or continuous spectra. == Characteristics == === Form factor === Many lamp units, or light bulbs, are specified in standardized shape codes and socket names. Incandescent bulbs and their retrofit replacements are often specified as "A19/A60 E26/E27", a common size for those kinds of light bulbs. In this example, the "A" parameters describe the bulb size and shape within the A-series light bulb while the "E" parameters describe the Edison screw base size and thread characteristics. === Comparison parameters === Common comparison parameters include: Luminous flux (in lumens) Energy consumption (in watts) Luminous efficacy (in lumens per watt) Color temperature (in kelvins) Less common parameters include color rendering index (CRI). === Life expectancy === Life expectancy for many types of lamp is defined as the number of hours of operation at which 50% of them fail, that is the median life of the lamps. Production tolerances as low as 1% can create a variance of 25% in lamp life, so in general some lamps will fail well before the rated life expectancy, and some will last much longer. For LEDs, lamp life is defined as the operation time at which 50% of lamps have experienced a 70% decrease in light output. In the 1900s the Phoebus cartel formed in an attempt to reduce the life of electric light bulbs, an example of planned obsolescence. Some types of lamp are also sensitive to switching cycles. Rooms with frequent switching, such as bathrooms, can expect much shorter lamp life than what is printed on the box. Compact fluorescent lamps are particularly sensitive to switching cycles. == Uses == The total amount of artificial light (especially from street light) is sufficient for cities to be easily visible at night from the air, and from space. External lighting grew at a rate of 3–6 percent for the later half of the 20th century and is the major source of light pollution that burdens astronomers and others with 80% of the world's population living in areas with night time light pollution. Light pollution has been shown to have a negative effect on some wildlife. Electric lamps can be used as heat sources, for example in incubators, as infrared lamps in fast food restaurants and toys such as the Kenner Easy-Bake Oven. Lamps can also be used for light therapy to deal with such issues as vitamin D deficiency, skin conditions such as acne and dermatitis, skin cancers, and seasonal affective disorder. Lamps which emit a specific frequency of blue light are also used to treat neonatal jaundice with the treatment which was initially undertaken in hospitals being able to be conducted at home. Electric lamps can also be used as a grow light to aid in plant growth especially in indoor hydroponics and aquatic plants with recent research into the most effective types of light for plant growth. Due to their nonlinear resistance characteristics, tungsten filament lamps have long been used as fast-acting thermistors in electronic circuits. Popular uses have included: Stabilization of sine wave oscillators Protection of tweeters in loudspeaker enclosures; excess current that is too high for the tweeter illuminates the light rather than destroying the tweeter. Automatic volume control in telephones == Cultural symbolism == In Western culture, a lightbulb — in particular, the appearance of an illuminated lightbulb above a person's head — signifies sudden inspiration. In the Middle East, a light bulb symbol has a sexual connotation. A stylized depiction of a light bulb features as the logo of the Turkish AK Party. == See also == Flameless candle Light tube List of light sources == References == == External links == Dark Sacred Night" (2023) is a short science film from the Princeton University Office of Sustainability about lighting obscuring the stars and affecting health and the environment.

An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic which secures the lamp in the socket of a light fixture, which is often called a "lamp" as well. The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet mount. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, such as fluorescent lamps, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric generators or battery systems. Battery-powered light is often reserved for when and where stationary lights fail, often in the form of flashlights or electric lanterns, as well as in vehicles.

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russian studies

Russistik (wiktionary)

IPA(key): /ʁʊˈsɪstɪk/, [ʁʊˈsɪstɪkʰ] Rhymes: -ɪstɪk Hyphenation: Rus‧sis‧tik Russistik f (genitive Russistik, no plural) Russian studies (academic discipline) Slawistik Russist Russistin russistisch “Russistik” in Duden online

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russian studies

Russian studies (wikipedia)

Russian studies is an interdisciplinary field crossing politics, history, culture, economics, and languages of Russia and its neighborhood, often grouped under Soviet and Communist studies. Russian studies should not be confused with the study of the Russian literature or linguistics, which is often a distinct department within universities. In university, a Russian studies major includes many cultural classes teaching Russian politics, history, geography, linguistics, Russian language, literature, and arts. Mysticism and folklore are commonly studied, the introduction of Christianity, rule under the tsars and expansion of Russian empire, later rule under communism, history of the Soviet Union, and its collapse and studies about present-day Russia. Russian studies rose in prominence during the Cold War, but experienced a decline after the collapse of the Soviet Union. Aggressive behavior by Russia, particularly its invasion of Ukraine, led to increased attention to Russian studies and a reevaluation of its precepts in terms of decolonization. == History == In the year 1897, During the last Emperor's reign of Russia, Czar Nikolai I implemented the public school system in Russia that had a population of 125 million people, but only around 26.5 million were literate in reading or writing. After his reign was over, Joseph Stalin took position of leader of the Soviet Union in the 1930s. He emphasized the industrialization of reform and need for engineers and scientists, which have led to Russia now being in the top 5 countries to rank #1 in Physics regional research reputation. The reform of their education system came from being 21.2% literate to 99.69% in 2021. == See also == Area studies Kremlinology List of Russian studies centers Russian culture Slavic studies Byzantine studies Education in Russia == References == == External links == Russian Studies at Petrozavodsk State University Russian Studies / University of Helsinki "Russia, Eastern Europe, and Eurasia: A Research Guide". Princeton LibGuides. US: Princeton University Library. "Russian and East European Studies". Research & Subject Guides. Washington, DC: Georgetown University Library. "All-Russian Primary Education (1894-1917): Developmental Milestones" Sochi State University https://www.sociostudies.org/journal/files/seh/2011_2/138-149.pdf

Russian studies is an interdisciplinary field crossing politics, history, culture, economics, and languages of Russia and its neighborhood, often grouped under Soviet and Communist studies. Russian studies should not be confused with the study of the Russian literature or linguistics, which is often a distinct department within universities. In university, a Russian studies major includes many cultural classes teaching Russian politics, history, geography, linguistics, Russian language, literature, and arts. Mysticism and folklore are commonly studied, the introduction of Christianity, rule under the tsars and expansion of Russian empire, later rule under communism, history of the Soviet Union, and its collapse and studies about present-day Russia. Russian studies rose in prominence during the Cold War, but experienced a decline after the collapse of the Soviet Union. Aggressive behavior by Russia, particularly its invasion of Ukraine, led to increased attention to Russian studies and a reevaluation of its precepts in terms of decolonization.

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Orphism (wikipedia)

Orphism may refer to: Orphism (art), a school of art, also known as "Orphic cubism" Orphism (religion), a religious movement in antiquity, supposed to have been founded by Orpheus

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Orphism (art) (wikipedia)

Orphism or Orphic Cubism, a term coined by the French poet Guillaume Apollinaire in 1912, was an offshoot of Cubism that focused on pure abstraction and bright colors, influenced by Fauvism, the theoretical writings of Paul Signac, Charles Henry and the dye chemist Michel Eugène Chevreul. This movement, perceived as key in the transition from Cubism to Abstract art, was pioneered by František Kupka, Robert Delaunay and Sonia Delaunay, who relaunched the use of color during the monochromatic phase of Cubism. The meaning of the term Orphism was elusive when it first appeared and remains to some extent vague. == History == The Orphists were rooted in Cubism but tended towards a pure lyrical abstraction. They saw art as the unification of sensation and color. More concerned with sensation, they began with recognizable subjects, depicted with abstract structures. Orphism aimed to vacate recognizable subject matter by concentrating exclusively on form and color. The movement also strove toward the ideals of Simultanism: endless interrelated states of being. The decomposition of spectral light in Neo-Impressionist color theory of Paul Signac and Charles Henry played an important role in the development of Orphism. Robert Delaunay, Albert Gleizes, and Gino Severini all knew Henry personally. A mathematician, inventor, and esthetician, Charles Henry was a close friend of the Symbolist writers Félix Fénéon and Gustave Kahn. He also knew Seurat, Signac and Pissarro, whom he met during the eighth and last Impressionist exhibition in 1886. Henry brought emotional associational theory into the realm of art: something that ultimately influenced the Neo-Impressionists. Henry and Seurat agreed that the basic elements of art—line, color and form—like words, could be treated independently, each with its own abstract quantity, independent of one another, or in unison, depending on the intention of the artist. "Seurat knows well" wrote Fénéton in 1889, "that the line, independent of its topographical role, possesses an assessable abstract value" in addition to the particles of color, and the relation to emotion of the viewer. The underlying theory behind Neo-Impressionsim had a lasting effect on the works of Delaunay. The Neo-Impressionists had succeeded in establishing an objective scientific basis for their painting in the domain of color, but only as regards the spectrum of light (for paint pigments the result was less scientific). The Cubists ultimately employed the theory to some extent in color, form and dynamics. The Symbolists perceived Orpheus of Greek mythology as the ideal artist. In 1907 Apollinaire wrote Bestiaire ou cortège d'Orphée, symbolizing Orpheus as a mystic and influential poet and artist, just as the Symbolists. The voice of light that Apollinaire mentioned in his poems was a metaphor for inner experiences. == Apollinaire == Apollinaire mentioned the term Orphism in an address at the Salon de la Section d'Or in 1912, referring to the pure painting of František Kupka. In his 1913 Les Peintres Cubistes, Méditations Esthétiques Apollinaire described Orphism as "the art of painting new totalities with elements that the artist does not take from visual reality, but creates entirely by himself. [...] An Orphic painter's works should convey an 'untroubled aesthetic pleasure', a meaningful structure and sublime significance." Orphism represented a new art-form, much as music was to literature. These analogies could be seen in the titles of paintings such as Kupka's Amorpha: Fugue in Two Colors (1912); Francis Picabia's Dance at the Source (1912) and Wassily Kandinsky's Über das Geistige in der Kunst (1912). Kandinsky described the relationships between sound and color. Robert Delaunay was concerned with color and music, and exhibited with the Blaue Reiter at the request of Kandinsky. The increasingly abstract paintings of Fernand Léger and Marcel Duchamp were also treated as Orphists by Apollinaire. == Exhibitions == The Salon de la Section d'Or in 1912 was the first exhibition that presented Orphism to the general public. In March 1913 Orphism was exhibited at the Salon des Indépendants in Paris. Reviewing the salon in Montjoie (29 March 1913) Apollinaire argued for the abolition of Cubism in favor of Orphism: "If Cubism is dead, long live Cubism. The kingdom of Orpheus is at hand!" The Autumn salon (Erster Deutscher Herbstsalon, Berlin) of 1913, organized by Herwarth Walden of Der Sturm, exhibited many works by Robert and Sonia Delaunay, Jean Metzinger's L'Oiseau bleu (1913, Musée d'Art Moderne de la Ville de Paris), Albert Gleizes' Les Joueurs de football (1912–13, National Gallery of Art), paintings by Picabia, and Léger, along with several Futurist works. From this exhibition Apollinaire's relation with R. Delaunay cooled, following remarks with Umberto Boccioni about the ambiguity of 'simultaneity'. Apollinaire no longer used the term Orphism in his subsequent writings and began instead promoting Picabia, Alexander Archipenko, and Futurist concepts. == The Delaunays == Robert Delaunay and his wife Sonia Terk Delaunay remained the main protagonists of the Orphic movement. Their earlier works focused on Fauvist colors, variously abstract; such as Sonia's 1907 Finnish Girl and Robert's 1906 Paysage au disque. The former relying on pure colors, the latter on color and mosaic-like brushstrokes painted under the influence of Jean Metzinger, also a Neo-Impressionist (with highly Divisionist and Fauve components) at the time. Even though Orphism was effectively dissolved before World War I, American painters Patrick Henry Bruce and Arthur Burdett Frost, two of R. Delaunay's pupils, embarked on a similar form of art from 1912 onward. The Synchromists Morgan Russell and Stanton Macdonald-Wright wrote their own manifestos in an attempt to differentiate themselves from the Orphism of the Delaunays. == See also == Purism De Stijl Crystal Cubism Orpheus (play) == References and sources == References Sources Baron, Stanley; Damase, Jacques. Sonia Delaunay: The Life of an Artist. Harry N. Abrams, Inc., 1995 Buckberrough, Sherry A. Robert Delaunay: The Discovery of Simultaneity. Ann Arbor, Michigan: UMI Research Press, 1978. Chadwick, Whitney; de Courtivron, Isabelle. (ed) Significant Others: Creativity and Intimate partnership. London: Thames & Hudson, 1993. Chip, Herschel B. "Orphism and Color Theory". The Art Bulletin, Vol. 40, No. 1, pp. 55–63, Mar 1958. Damase, Jacque. Sonia Delaunay: Rhythms and Colours. Greenwich, Connecticut: New York Graphic Society Ltd, 1972. Gale, Matthew. Dada and Surrealism. New York: Phaidon Press Inc., 2006 Hughes, Gordon "Envisioning Abstraction: The Simultaneity of Robert Delaunay's First Disk". The Art Bulletin, Vol. 89, No. 2, pp. 306–332, Jun 2007. The College Art Association. MoMA. Orphism Seidner, David. Sonia Delaunay. BOMB Magazine, 2/Winter, ART, 1982. BOMB Magazine: Sonia Delauney by David Seidner Stangoes, Nikos (ed). Concepts of Modern Art: Fauvism to Post-Modernism. Chapter: "Orphism", Virginia Spate. (Revised) London: Thames & Hudson, 1981. == External links == MoMA Collection: Robert Delaunay MoMA Collection: Sonia Delaunay MoMA Collection: František Kupka Agence photographique de la réunion des Musées nationaux

Orphism or Orphic Cubism, a term coined by the French poet Guillaume Apollinaire in 1912, was an offshoot of Cubism that focused on pure abstraction and bright colors, influenced by Fauvism, the theoretical writings of Paul Signac, Charles Henry and the dye chemist Michel Eugène Chevreul. This movement, perceived as key in the transition from Cubism to Abstract art, was pioneered by František Kupka, Robert Delaunay and Sonia Delaunay, who relaunched the use of color during the monochromatic phase of Cubism. The meaning of the term Orphism was elusive when it first appeared and remains to some extent vague.

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Orphism (religion) (wikipedia)

Orphism (more rarely Orphicism; Ancient Greek: Ὀρφικά, romanized: Orphiká) is the name given to a set of religious beliefs and practices originating in Thrace and later spreading to the ancient Greek and Hellenistic world, associated with literature ascribed to the mythical Thracian poet Orpheus, who descended into the Greek underworld and returned. This type of journey is called a katabasis and is the basis of several hero worships and journeys. Orphics revered Dionysus (who once descended into the Underworld and returned) and Persephone (who annually descended into the Underworld for a season and then returned). Orphism has been described as a reform of the earlier Dionysian religion, involving a re-interpretation or re-reading of the myth of Dionysus and a re-ordering of Hesiod's Theogony, based in part on pre-Socratic philosophy. The suffering and death of the god Dionysus at the hands of the Titans has been considered the central myth of Orphism. According to this myth, the infant Dionysus is killed, torn apart, and consumed by the Titans. In retribution, Zeus strikes the Titans with a thunderbolt, turning them to ash. From these ashes, humanity is born. In Orphic belief, this myth describes humanity as having a dual nature: body (Ancient Greek: σῶμα, romanized: sôma), inherited from the Titans, and a divine spark or soul (Ancient Greek: ψυχή, romanized: psukhḗ), inherited from Dionysus. In order to achieve salvation from the Titanic, material existence, one had to be initiated into the Dionysian mysteries and undergo teletē, a ritual purification and reliving of the suffering and death of the god. Orphics believed that they would, after death, spend eternity alongside Orpheus and other heroes. The uninitiated (Ancient Greek: ἀμύητος, romanized: amúētos), they believed, would be reincarnated indefinitely. == History == Orphism is named after the legendary poet-hero Orpheus, who was said to have originated the Mysteries of Dionysus. However, Orpheus was more closely associated with Apollo than to Dionysus in the earliest sources and iconography. According to some versions of his mythos, he was the son of Apollo, and during his last days, he shunned the worship of other gods and devoted himself to Apollo alone. === Origins === Poetry containing distinctly Orphic beliefs has been traced back to the 6th century BC or at least 5th century BC, and graffiti of the 5th century BC apparently refers to "Orphics". The Derveni papyrus allows Orphic mythology to be dated to the end of the 5th century BC, and it is probably even older. Orphic views and practices are attested as by Herodotus, Euripides, and Plato. Plato refers to "Orpheus-initiators" (Ὀρφεοτελεσταί), and associated rites, although how far "Orphic" literature in general related to these rites is not certain. === Relationship to Pythagoreanism === Orphic views and practices have parallels to elements of Pythagoreanism, and various traditions hold that the Pythagoreans or Pythagoras himself authored early Orphic works; alternately, later philosophers believed that Pythagoras was an initiate of Orphism. The extent to which one movement may have influenced the other remains controversial. Some scholars maintain that Orphism and Pythagoreanism began as separate traditions which later became confused and conflated due to a few similarities. Others argue that the two traditions share a common origin and can even be considered a single entity, termed "Orphico-Pythagoreanism." The belief that Pythagoreanism was a subset or direct descendant of Orphic religion existed by late antiquity, when Neoplatonist philosophers took the Orphic origin of Pythagorean teachings at face value. Proclus wrote: all that Orpheus transmitted through secret discourses connected to the mysteries, Pythagoras learnt thoroughly when he completed the initiation at Libethra in Thrace, and Aglaophamus, the initiator, revealed to him the wisdom about the gods that Orpheus acquired from his mother Calliope. In the fifteenth century, the Neoplatonic Greek scholar Constantine Lascaris (who found the poem Argonautica Orphica) considered a Pythagorean Orpheus. Bertrand Russell (1947) noted: The Orphics were an ascetic sect; wine, to them, was only a symbol, as, later, in the Christian sacrament. The intoxication that they sought was that of "enthusiasm," of union with the god. They believed themselves, in this way, to acquire mystic knowledge not obtainable by ordinary means. This mystical element entered into Greek philosophy with Pythagoras, who was a reformer of Orphism as Orpheus was a reformer of the religion of Dionysus. From Pythagoras Orphic elements entered into the philosophy of Plato, and from Plato into most later philosophy that was in any degree religious. Study of early Orphic and Pythagorean sources, however, is more ambiguous concerning their relationship, and authors writing closer to Pythagoras' own lifetime never mentioned his supposed initiation into Orphism, and in general regarded Orpheus himself as a mythological figure. Despite this, even these authors of the 5th and 4th centuries BC noted a strong similarity between the two doctrines. In fact, some claimed that rather than being an initiate of Orphism, Pythagoras was actually the original author of the first Orphic texts. Specifically, Ion of Chios claimed that Pythagoras authored poetry which he attributed to the mythical Orpheus, and Epigenes, in his On Works Attributed to Orpheus, attributed the authorship of several influential Orphic poems to notable early Pythagoreans, including Cercops. According to Cicero, Aristotle also claimed that Orpheus never existed, and that the Pythagoreans ascribed some Orphic poems to Cercon (see Cercops). Belief in metempsychosis was common to both currents, although it also seems to contain differences. Where the Orphics taught about a cycle of grievous embodiments that could be escaped through their rites, Pythagoras seemed to teach about an eternal, neutral metempsychosis against which personal actions would be irrelevant. The Neoplatonists regarded the theology of Orpheus, carried forward through Pythagoreanism, as the core of the original Greek religious tradition. Proclus, an influential neoplatonic philosopher, one of the last major classical philosophers of late antiquity, says "For all the Grecian theology is the progeny of the mystic tradition of Orpheus; Pythagoras first of all learning from Aglaophemus the rites of the gods, but Plato in the second place receiving an all-perfect science of the divinities from the Pythagoric and Orphic writings." (trans. Thomas Taylor, 1816) == Orphic literature == A number of Greek religious poems in hexameters were attributed to Orpheus, as they were to similar miracle-working figures, like Bakis, Musaeus, Abaris, Aristeas, Epimenides, and the Sibyl. Of this vast literature, only two works survived whole: the Orphic Hymns, a set of 87 poems, possibly composed at some point in the second or third century, and the epic Orphic Argonautica, composed somewhere between the fourth and sixth centuries. Earlier Orphic literature, which may date back as far as the sixth century BC, survives only in papyrus fragments or in quotations. === Orphic Hymns === The Orphic Hymns are 87 hexametric poems of a shorter length composed in the Roman Imperial age. === Orphic Argonautica === The Orphic Argonautica (Greek: Ὀρφέως Ἀργοναυτικά) is a Greek epic poem dating from the 4th century CE of unknown authorship. It is narrated in the first person in the name of Orpheus and tells the story of Jason and the Argonauts. The narrative is basically similar to that in other versions of the story, such as the Argonautica of Apollonius Rhodius, on which it is probably based. The main differences are the emphasis on the role of Orpheus and a more mythological, less realistic technique of narration. In the Argonautica Orphica, unlike in Apollonius Rhodius, it is claimed that the Argo was the first ship ever built. === Derveni papyrus === The Derveni papyrus, found in Derveni, Macedonia (Greece) in 1962, contains a philosophical treatise that is an allegorical commentary on an Orphic poem in hexameters, a theogony concerning the birth of the gods, produced in the circle of the philosopher Anaxagoras, written in the second half of the fifth century BC. Fragments of the poem are quoted making it "the most important new piece of evidence about Greek philosophy and religion to come to light since the Renaissance". The papyrus dates to around 340 BC, during the reign of Philip II of Macedon, making it Europe's oldest surviving manuscript. === Theogonies === The Orphic theogonies are works which present accounts of the origin of the gods, much like the Theogony of Hesiod. These theogonies are symbolically similar to Near Eastern models. The main story has it that Zagreus, Dionysus' previous incarnation, is the son of Zeus and Persephone. Zeus names the child as his successor, which angers his wife Hera. She instigates the Titans to murder the child. Zagreus is then tricked with a mirror and children's toys by the Titans, who shred him to pieces and consume him. Athena saves the heart and tells Zeus of the crime, who in turn hurls a thunderbolt on the Titans. The resulting soot, from which sinful mankind is born, contains the bodies of the Titans and Zagreus. The soul of man (the Dionysus part) is therefore divine, but the body (the Titan part) holds the soul in bondage. Thus, it was declared that the soul returns to a host ten times, bound to the wheel of rebirth. Following the punishment, the dismembered limbs of Zagreus were cautiously collected by Apollo who buried them in his sacred land Delphi. ==== Orphic Egg ==== In Orphic theogonies, the Orphic Egg is a cosmic egg from which hatched the primordial hermaphroditic deity Phanes/Protogonus (variously equated also with Zeus, Pan, Metis, Eros, Erikepaios and Bromius), who in turn created the other gods. The egg is often depicted with the serpent-like creature, Ananke, wound about it. Phanes is the golden winged primordial being who was hatched from the shining cosmic egg that was the source of the universe. Called Protogonos (First-Born) and Eros (Love) an ancient Orphic hymn addresses him thus:Ineffable, hidden, brilliant scion, whose motion is whirring, you scattered the dark mist that lay before your eyes and, flapping your wings, you whirled about, and through this world you brought pure light. ==== Variations ==== There are two Orphic stories of the rebirth of Dionysus: in one it is the heart of Dionysus that is implanted into the thigh of Zeus; in the other Zeus has impregnated the mortal woman Semele, resulting in Dionysus's literal rebirth. Many of these details differ from accounts in the classical authors. Damascius says that Apollo "gathers him (Dionysus) together and brings him back up". The main difference seems to be in the primordial succession: In the Eudemian Theogony (5th century BC), the first being to exist is Night (Nyx). In the Rhapsodic Theogony, it starts with Chronos ('Unageing Time', different from Kronos, Zeus' father) who gives birth to Ether and Chaos, and then lays the egg from which Phanes/Protogonos arises. In the Hieronyman Theogony, the egg arises from soil (more specifically 'the matter out of which earth was coagulated') and water, and it is 'Unageing Time' Kronos which arises from it, and gives birth to Ether, Chaos and Erebus. Then Kronos lays a new egg in Chaos, from which arises Protogonos. In the Derveni Theogony, the Night lays the egg from which Protogonos arises, he then give birth to Ouranos & Gaia, which give birth to Kronos, himself father of Zeus who end up swallowing the primordial egg of Protogonos and recreating the Universe in the process. But there are other differences, notably in the treatment of Dionysos: In the Rhapsodic Theogony, Dionysos is dismembered and cooked by the Titans before Zeus struck them with lightning (mankind then arises from the soot, and Dionysos is resurrected from his preserved heart). The Derveni Papyrus being fragmentary, the story stops without having mentioned him. The Hieronyman Theogony does not include Dionysos being eaten by the Titans, as both sources for the work (Damascius and Athenagoras) do not mention it, despite the latter describing the war on the Titans. In later centuries, these versions underwent a development where Apollo's act of burying became responsible for the reincarnation of Dionysus, thus giving Apollo the title Dionysiodotes (bestower of Dionysus). Apollo plays an important part in the dismemberment myth because he represents the reverting of Encosmic Soul back towards unification. === Gold tablets === Surviving written fragments show a number of beliefs about the afterlife similar to those in the "Orphic" mythology about Dionysus' death and resurrection. Bone tablets found in Olbia (5th century BC) carry short and enigmatic inscriptions like: "Life. Death. Life. Truth. Dio(nysus). Orphics." The function of these bone tablets is unknown. Gold-leaf tablets found in graves from Thurii, Hipponium, Thessaly and Crete (4th century BC and after) give instructions to the dead. Although these thin tablets are often highly fragmentary, collectively they present a shared scenario of the passage into the afterlife. When the deceased arrives in the underworld, he is expected to confront obstacles. He must take care not to drink of Lethe ("Forgetfulness"), but of the pool of Mnemosyne ("Memory"). He is provided with formulaic expressions with which to present himself to the guardians of the afterlife. As said in the Petelia tablet: I am a son of Earth and starry sky. I am parched with thirst and am dying; but quickly grant me cold water from the Lake of Memory to drink. Other gold leaves offer instructions for addressing the rulers of the underworld: Now you have died and now you have come into being, O thrice happy one, on this same day. Tell Persephone that the Bacchic One himself released you. == Notes == == Bibliography == === Editions and translations === Athanassakis, Apostolos N. Orphic Hymns: Text, Translation, and Notes. Missoula: Scholars Press for the Society of Biblical Literature, 1977. ISBN 978-0-89130-119-6 Bernabé, Albertus (ed.), Orphicorum et Orphicis similium testimonia et fragmenta. Poetae Epici Graeci. Pars II. Fasc. 1. Bibliotheca Teubneriana, München/Leipzig: K.G. Saur, 2004. ISBN 3-598-71707-5 Kern, Otto. Orphicorum fragmenta, Berolini apud Weidmannos, 1922. Graf, Fritz; Johnston, Sarah (2007). Ritual Texts for the Afterlife: Orpheus and the Bacchic Gold Tablets. Routledge. ISBN 978-0-415-41550-7. Retrieved 10 August 2023. === References === Betegh, Gábor (19 November 2007). The Derveni Papyrus: Cosmology, Theology and Interpretation. Cambridge University Press. ISBN 978-0-521-04739-5. Retrieved 10 August 2023. Betegh, Gábor (24 April 2014). "Pythagoreans, Orphism and Greek Religion". In Huffman, Carl A. (ed.). A History of Pythagoreanism. Cambridge University Press. pp. 149–66. ISBN 978-1-139-91598-4. Guthrie, William Keith Chambers (1935). Orpheus and Greek Religion: A Study of the Orphic Movement. Methuen & Company, Limited. Guthrie, William Keith Chambers (1955). The Greeks and Their Gods. by W.K.C. Guthrie. Beacon Press. Retrieved 10 August 2023. Kirk, G. S.; Raven, J. E.; Schofield, M. (29 December 1983). The Presocratic Philosophers: A Critical History with a Selection of Texts. Cambridge University Press. ISBN 978-0-521-27455-5. Meisner, Dwayne A. (2018). Orphic Tradition and the Birth of the Gods. Oxford University Press. ISBN 978-0-19-066352-0. Retrieved 10 August 2023. Sider, David; Obbink, Dirk (30 October 2013). Doctrine and Doxography. ISBN 978-3-11-033137-0. Richardson, N. J. (1985). "The Orphic Poems". The Classical Review. 35 (1): 87–90. doi:10.1017/S0009840X00107474. JSTOR 3063696. S2CID 162276006. Parker, Robert (1995). "Early Orphism". In Powell, Anton (ed.). The Greek World. Psychology Press. pp. 483–510. ISBN 978-0-415-06031-8. Retrieved 10 August 2023. West, Martin Litchfield (1983). The Orphic Poems. Clarendon Press. ISBN 978-0-19-814854-8. Retrieved 10 August 2023. == Further reading == === Articles on Orphism === Bernabé, Alberto. "Some Thoughts about the 'New' Gold Tablet from Pherai." Zeitschrift für Papyrologie und Epigraphik 166 (2008): 53–58. Bremmer, Jan. "Orphism, Pythagoras, and the Rise of the Immortal Soul". The Rise and Fall of the Afterlife: The 1995 Read-Tuckwell Lectures at the University of Bristol. New York: Routledge, 2002. 11–26. ISBN 978-0-415-14147-5 Bremmer, Jan. "Rationalization and Disenchantment in Ancient Greece: Max Weber among the Pythagoreans and Orphics?" From Myth to Reason: Studies in the Development of Greek Thought. Ed. Richard Buxton. Oxford: Oxford University Press, 1999. 71–83. Bremmer, Jan N. (2013). "Divinities in the Orphic Gold Leaves: Euklês, Eubouleus, Brimo, Kybele, Kore and Persephone". Zeitschrift für Papyrologie und Epigraphik. 187: 35–48. JSTOR 23850747. Comparetti, Domenico, and Cecil Smith. "The Petelia Gold Tablet". The Journal of Hellenic Studies 3 (1882): 111–18. Edmunds, Radcliffe. "Tearing Apart the Zagreus Myth: A Few Disparaging Remarks on Orphism and Original Sin." Classical Antiquity 18.1 (1999): 35–73. Finkelberg, Aryeh. "On the Unity of Orphic and Milesian Thought". The Harvard Theological Review 79 (1986): 321–35. ISSN 0017-8160 Graf, Fritz. "Dionysian and Orphic Eschatology: New Texts and Old Questions". Masks of Dionysus. Ed. T. Carpenter and C. Faraone. Ithaca: Cornell UP, 1993. 239–58, ISSN 0012-9356. Fulińska, Agnieszka (1 January 1970). "Dionysos, Orpheus and Argead Macedonia: Overwiev and Perspectives". Classica Cracoviensia. 17: 43–67. doi:10.12797/CC.17.2014.17.03. Robertson, Noel. "Orphic Mysteries and Dionysiac Ritual." Greek Mysteries: the Archaeology and Ritual of Ancient Greek Secret Cults. Ed. Michael B. Cosmopoulos. New York: Routledge, 2004. 218–40, ISBN 978-0-415-24872-3. Torjussen, Stian (September 2005). "Phanes and Dionysos in the Derveni Theogony". Symbolae Osloenses. 80 (1): 7–22. doi:10.1080/00397670600684691. S2CID 170976252. West, Martin L. "Graeco-Oriental Orphism in the 3rd cent. BC". Assimilation et résistence à la culture Gréco-romaine dans le monde ancient: Travaux du VIe Congrès International d'Etudes Classiques. Ed.D. M. Pippidi. Paris: Belles Lettres, 1976. 221–26. === Books on Orphism === Alderink, Larry J. (1981). Creation and Salvation in Ancient Orphism. American Philological Association. ISBN 978-0-89130-502-6. Retrieved 10 August 2023. Bernabé, Alberto; Cristóbal, Ana Isabel Jiménez San (30 January 2008). Instructions for the Netherworld: The Orphic Gold Tablets. BRILL. ISBN 978-90-474-2374-4. Retrieved 10 August 2023. Brisson, Luc (1995). Orphée Et L'orphisme Dans L'antiquité Gréco-romaine. Variorum. ISBN 978-0-86078-453-1. Retrieved 10 August 2023. Burkert, Walter. "Craft Versus Sect: The Problem of Orphics and Pythagoreans". Jewish and Christian Self-Definition: Volume Three - Self-Definition in the Greco-Roman World. Ed. B. Meyer and E. P. Sanders. Philadelphia: Fortress, 1982. Carratelli, Giovanni Pugliese (2001). Le lamine d'oro orfiche: istruzioni per il viaggio oltremondano degli iniziati greci (in Italian). Adelphi. ISBN 978-88-459-1663-2. Retrieved 10 August 2023. Chrysanthou, Anthi (20 April 2020). Defining Orphism: The Beliefs, the 'teletae' and the Writings. Walter de Gruyter GmbH & Co KG. ISBN 978-3-11-067845-1. Retrieved 10 August 2023. Edmonds, Radcliffe G. (20 September 2004). Myths of the Underworld Journey: Plato, Aristophanes, and the 'Orphic' Gold Tablets. Cambridge University Press. ISBN 978-0-521-83434-6. Retrieved 10 August 2023. Edmonds, Radcliffe G. (7 November 2013). Redefining Ancient Orphism: A Study in Greek Religion. Cambridge University Press. ISBN 978-1-107-03821-9. Retrieved 10 August 2023. Graf, Fritz (1974). Eleusis und die orphische Dichtung Athens in vorhellenistischer Zeit (in German). Walter de Gruyter. ISBN 978-3-11-004498-0. Retrieved 10 August 2023. Jáuregui, Miguel Herrero de (26 March 2010). Orphism and Christianity in Late Antiquity. Walter de Gruyter. ISBN 978-3-11-021660-8. Retrieved 10 August 2023. Jáuregui, Miguel Herrero de; Cristóbal, Ana Isabel Jiménez San; Martínez, Eugenio R. Luján; Hernández, Raquel Martín; Álvarez, Marco Antonio Santamaría; Tovar, Sofía Torallas (8 December 2011). Tracing Orpheus: Studies of Orphic Fragments. Walter de Gruyter. ISBN 978-3-11-026053-3. Linforth, Ivan Mortimer (1973). The Arts of Orpheus. Arno Press. ISBN 978-0-405-04847-0. Retrieved 10 August 2023. === General studies === Albinus, L. (2000). The house of Hades: Studies in ancient Greek eschatology. Aarhus [Denmark: Aarhus University Press. ISBN 978-87-7288-833-0 Burkert, Walter (2004). Babylon, Memphis, Persepolis: Eastern Contexts of Greek Culture. Harvard University Press. ISBN 978-0-674-01489-3. Retrieved 10 August 2023. Martin, Luther H. Hellenistic Religions: An Introduction 1987, 102, ISBN 978-0-19-504390-7. Russo, Attilio (2004). "Costantino Lascaris tra fama e oblio nel Cinquecento messinese", Archivio Storico Messinese, Messina 2003–2004, LXXXIV-LXXXV, 5–87, especially 53–54. Sournia Alain. Chap. "Sapesse orientale et philosophie occidentale : la période axiale" in Fondements d'une philosophie sauvage. Connaissances et savoirs, 2012, 300 p., ISBN 978-2-7539-0187-2. Zuntz, Günther. Persephone: Three Essays on Religion and Thought in Magna Graecia. Oxford: Clarendon Press, 1971, ISBN 978-0-19-814286-7. == External links == Online Text: The Orphic Hymns translated by Thomas Taylor The Orphic Hymns translated by Thomas Taylor – alternative version Alexander Fol, Orphica Magica I, Sofia 2004 Rosicrucian Digest vol. 87 devoted entirely to Orphism Edmonds, Radcliffe. "Tearing Apart the Zagreus Myth: A Few Disparaging Remarks on Orphism and Original Sin." Classical Antiquity 18.1 (1999): 35–73. A Genealogy of Philosophic Enlightenment in Classical Greece Orphism in the modern world

Orphism (more rarely Orphicism; Ancient Greek: Ὀρφικά, romanized: Orphiká) is the name given to a set of religious beliefs and practices originating in Thrace and later spreading to the ancient Greek and Hellenistic world, associated with literature ascribed to the mythical Thracian poet Orpheus, who descended into the Greek underworld and returned. This type of journey is called a katabasis and is the basis of several hero worships and journeys. Orphics revered Dionysus (who once descended into the Underworld and returned) and Persephone (who annually descended into the Underworld for a season and then returned). Orphism has been described as a reform of the earlier Dionysian religion, involving a re-interpretation or re-reading of the myth of Dionysus and a re-ordering of Hesiod's Theogony, based in part on pre-Socratic philosophy. The suffering and death of the god Dionysus at the hands of the Titans has been considered the central myth of Orphism. According to this myth, the infant Dionysus is killed, torn apart, and consumed by the Titans. In retribution, Zeus strikes the Titans with a thunderbolt, turning them to ash. From these ashes, humanity is born. In Orphic belief, this myth describes humanity as having a dual nature: body (Ancient Greek: σῶμα, romanized: sôma), inherited from the Titans, and a divine spark or soul (Ancient Greek: ψυχή, romanized: psukhḗ), inherited from Dionysus. In order to achieve salvation from the Titanic, material existence, one had to be initiated into the Dionysian mysteries and undergo teletē, a ritual purification and reliving of the suffering and death of the god. Orphics believed that they would, after death, spend eternity alongside Orpheus and other heroes. The uninitiated (Ancient Greek: ἀμύητος, romanized: amúētos), they believed, would be reincarnated indefinitely.

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Kyffhäuser Monument (wikipedia)

The Kyffhäuser Monument (German: Kyffhäuserdenkmal), also known as Barbarossa Monument (Barbarossadenkmal), is an Emperor William monument in the Kyffhäuser mountain range in the German state of Thuringia. It was erected from 1890 to 1896 atop the ruins of the medieval Kyffhausen Castle near Bad Frankenhausen. Designed by architect Bruno Schmitz (1858–1916), it is the third-largest monument in Germany. Schmitz has also designed the two largest memorials, the Monument to the Battle of the Nations, that commemorates the 1813 Battle of Leipzig and the Emperor William Monument at the Porta Westfalica. == Geography == The monument has a total height of 81 m (266 ft) and is located at an elevation of 420 m (1,380 ft) on top of an 800 m (2,600 ft) long outcrop of the eastern Kyffhäuser range, below the 439 m (1,440 ft) high mountain peak of the Kyffhausen Castle. The site lies within the Steinthaleben community in the Kyffhäuserland district, about 6.5 km (4.0 mi) north of Bad Frankenhausen and southwest of Tilleda in the Goldene Aue plain. == History == After the 1888 death of emperor William I, numerous memorials were erected in his honour all over Germany. The Kyffhäuser Monument had initially been proposed by the 19th century War Veterans Federation (Deutscher Kriegerbund), which as Kyffhäuser Federation (Kyffhäuserbund) took over its management around 1900. Architect Bruno Schmitz drew up plans in accordance with the late 19th century tradition of imperial grandeur, realized in massive stone structures like the Walhalla in Bavaria, the Hermannsdenkmal in the Teutoburg Forest, and the Niederwalddenkmal near Rüdesheim. The monument sits among the ruins (the upper and lower castle) of the medieval Imperial castle of Kyffhausen, that, built beginning around 1,000 AD, reached its maximal extent during the reign of the Hohenstaufen emperor Frederick I Barbarossa. Curious evidence of the medieval imperial castle has been preserved, such as the world's deepest castle well of 176 m (577 ft) depth. The 17 m (56 ft) high keep on the site of the former upper Kyffhausen castle is accessible and houses two exhibitions. Parts of the old gate structures have also been preserved. The Castle Museum focuses on the history of the ancient castle complex, the Barbarossa Saga and the construction history of the Emperor Wilhelm monument. The Museum also exhibits numerous artefacts, that were unearthed during excavations and conservation work by the Kyffhäuser Federation in and around the medieval castle. Architect Bruno Schmitz had borrowed romanesque style elements from the Hohenstaufen castles and fortresses of the 12th and 13th centuries for his Monument walls and towers. The roughly hewn stones are reminiscent of the Hohenstaufen hump block masonry, that were also used on the Barbarossa tower. The 1871 founded Prussian-dominated empire, was to be understood as the legitimate successor to the medieval Holy Roman Empire. It also signifies the national theme of decline and rebirth. The Prusso-German authorities were also aware of necessary integration concepts for the non-Prussian population. The nation was to be forged through empire as national identity was expressed in bombastic imperial stone iconography and was to be achieved as an imperial people, with an emperor as head of state and it was to develop imperial ambitions – domestic, European and global. == Features == A little scenic stone quarry surrounded by terraces on the east side of the monument forms the backdrop for the emperor Frederick Barbarossa sandstone sculpture created by Nikolaus Geiger (1849–1897). The 6.5 m (21 ft) high figure was fashioned on site from several sandstone blocks. At its feet linger knights, mythical creatures and members of his court, with whom the old emperor is lying in wait for resurrection in his underground dungeon. The Barabarossa legend holds, that he would rise again when Germany was in need of his leadership. The emperor himself is depicted as one might imagine an ancient powerful monarch in poems and legends at the very moment of awakening. This moment has been highlighted by the cawling movement of the left hand, that rests in the bottom-long beard and a slightly recessed leg that is not covered by the coat. The emperor doesn't really sleep, he even winks with one eye. Sculptor Nikolaus Geiger decorated the emperor's red beard with the imperial crown, as its original is on display in the Vienna Hofburg. Above him towers an equestrian statue of Emperor William I, designed by sculptor Emil Hundrieser (1846–1911) in Neo-baroque style. Wilhelm is depicted as a general, with Pickelhaube and Grand Cross of the Iron Cross, he poses on horseback in a dignified manner. He is flanked by two allegorical sculptures. To the right a Germanic warrior, who represents defense and to the left a woman, holding a pen and an oak leaf wreath, symbolizing history. Both, the Barbarossa and the Wilhelm sculptures represent the idea of the monument's program - the glorification of the monarchy and the military strength of the empire. The whole group has a height of almost 11 m (36 ft) and weighs around 16 tons. The driven copper sheets have a thickness of 2 to 3 mm (0.079 to 0.118 in). The Wilhelm sculpture is attached to a 57-metre (187 ft) tower, which is topped by a huge imperial crown. A 247-step stairway leads to a platform on top of the tower, that offers a panoramic view over the Kyffhäuser range to the Harz mountains in the north and down to the Thuringian Forest in the south. Since 2014 the site is run by the Kur & Tourismus GmbH Bad Frankenhausen after the Kyffhäuser-Tourismusverband had run into financial difficulties. == See also == Barbarossa Cave Cultural depictions of Frederick I, Holy Roman Emperor == References == == Further reading == Gunther Mai: Das Kyffhäuser-Denkmal 1896–1996; Böhlau Verlag; 1997; ISBN 3-412-02397-3 Rudy Koshar: From Monuments to Traces: Artifacts of German Memory, 1870–1990; University of California Press, 2000; ISBN 0-520-21768-3. == External links == Official website by the Kyffhäuser Tourist Association Kyffhäuserdenkmal (in German)

The Kyffhäuser Monument (German: Kyffhäuserdenkmal), also known as Barbarossa Monument (Barbarossadenkmal), is an Emperor William monument in the Kyffhäuser mountain range in the German state of Thuringia. It was erected from 1890 to 1896 atop the ruins of the medieval Kyffhausen Castle near Bad Frankenhausen. Designed by architect Bruno Schmitz (1858–1916), it is the third-largest monument in Germany. Schmitz has also designed the two largest memorials, the Monument to the Battle of the Nations, that commemorates the 1813 Battle of Leipzig and the Emperor William Monument at the Porta Westfalica.

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silk road

Seidenstraße (wiktionary)

Seidenstrasse (Switzerland, Liechtenstein) From Seide (“silk”) +‎ Straße (“street, road”). Coined by Ferdinand von Richthofen. IPA(key): /ˈzaɪ̯dn̩ˌʃtʁaːsə/ die Seidenstraße f (proper noun, usually definite, definite genitive der Seidenstraße) (history) Silk Road Seidenstraße on the German Wikipedia.Wikipedia de “Seidenstraße” in Digitales Wörterbuch der deutschen Sprache “Seidenstraße” in Duden online

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Silk Road (album) (wikipedia)

Silk Road is an album by Art Farmer which was recorded in 1996 and released on the Arabesque label the following year. == Reception == The AllMusic review by Scott Yanow said "Art Farmer has long been one of the most consistent of all brassmen. Playing the flumpet (which is a cross between a trumpet and a flugelhorn), Farmer is heard throughout this 1996 set in top form ... While his sidemen play quite well, the warm-toned and swinging Farmer is consistently the main star, and at age 68 he proves to still be in his prime". In JazzTimes, Jim Ferguson wrote "Richly melodic but bold, Farmer’s influential, distinctive approach is facilitated by his full-toned instrument-the flumpet, a cross between the trumpet and the fluegelhorn. Throughout this eight-tune set, he demonstrates that he is as adept at selecting material and personnel as he is at playing ... Rife with winning performances, Silk Road reflects the current state of one of jazz’s best". == Track listing == "Tonk" (Ray Bryant) – 6:38 "Ancient Evening" (Geoff Keezer) – 8:26 "Stardust" (Hoagy Carmichael, Mitchell Parish) – 5:38 "Dance of the One" (Don Braden) – 7:34 "Silk Road" (Keezer) – 5:51 "Flashback" (Art Farmer) – 6:59 "I Let a Song Go Out of My Heart" (Duke Ellington, Irving Mills, Henry Nemo, John Redmond) – 7:50 "Coming Home" (Kenny Davis) – 6:41 == Personnel == Art Farmer – flumpet Ron Blake, Don Braden – tenor saxophone, soprano saxophone Geoff Keezer – piano Kenny Davis – double bass Carl Allen – drums == References ==

Silk Road is an album by Art Farmer which was recorded in 1996 and released on the Arabesque label the following year.

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silk road

Silk Road (disambiguation) (wikipedia)

The Silk Road is a number of trade routes across the Eurasian landmass. Silk Road may also refer to: == Art and media == === Films and television === The Silk Road (Japanese TV series), a 1980 documentary produced by Japan's NHK The Silk Road (film), a 1988 Japanese film The Maritime Silk Road (film), a 2011 Iranian movie The Silk Road (British TV series), a 2016 documentary by the BBC, in three episodes, presented by Sam Willis Silk Road (film), about the online marketplace of the same name === Games === Silkroad Online, a 2005 free multiplayer online game === Literature === Silk Road, a novel by Jeanne Larsen Silk Road, a book by Eileen Ormsby of All Things Vice Silk Road, 2011 book written by Colin Falconer (writer) The Silk Roads: A New History of the World, 2015 book written by Peter Frankopan The Silk Road: Trade, Travel, War and Faith, 2004 book written by Susan Whitfield Silk Roads. Peoples, Cultures, Landscapes., 2019 book written by Susan Whitfield === Music === Silk Road (album), a 1997 album by Art Farmer Silk Road, for string quartet Tan Dun Silk Road Fantasia, Zhao Jiping Silk Road, album by Kitarō Silk Road Suite, a 1996 musical compositions by Kitarō for the NHK documentary series "Silk Road", song by Rick Ross from Black Market (Rick Ross album) === Theater === Silk Road Rising, a theater company in downtown Chicago == Companies and organizations == Silk Road (marketplace), anonymous online black market (Tor hidden service) best known for the illegal drug trade, active from 2011 to 2013 Silkroad (arts organization), a non-profit organization initiated by cellist Yo-Yo Ma == See also == Belt and Road Initiative Maritime Silk Road (disambiguation) New Silk Road (disambiguation) Silk Route (disambiguation) Silk Way (disambiguation)

The Silk Road is a number of trade routes across the Eurasian landmass. Silk Road may also refer to:

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silk road

Silk Road (film) (wikipedia)

Silk Road is a 2021 American crime thriller film, written for the screen and directed by Tiller Russell based on the Rolling Stone article "Dead End on Silk Road: Internet Crime Kingpin Ross Ulbricht's Big Fall" by David Kushner. The film stars Jason Clarke, Nick Robinson, Alexandra Shipp, Jimmi Simpson, Paul Walter Hauser, Darrell Britt-Gibson, and Will Ropp. It is based on the true story of Ross Ulbricht who develops a website on the darknet, an act which attracts the attention of the FBI and DEA who send in federal agent Richard "Rick" Bowden, a fictional composite of real life DEA Agent Carl Force and US Secret Service Special Agent Shaun Bridges, both of whom were convicted of felonies related to theft of assets in the investigation of Ulbricht, to bring down Ross' empire. Silk Road was released in the United States on February 19, 2021 by Lionsgate. == Plot == The film begins with Ross Ulbricht's arrest in San Francisco in 2013. It then delves into Ross's background, portraying him as a well-educated aspiring entrepreneur living in Austin, Texas. Ross comes up with the idea for Silk Road as a way to challenge government control and regulations, believing in the idea of taking back liberty. He starts the website to allow anonymous buying and selling of illegal goods. The movie introduces Ross Ulbricht, a charismatic and tech-savvy young man who creates the Silk Road, an underground website that facilitates the sale of illegal drugs and other contraband using cryptocurrencies. Ulbricht adopts the alias "Dread Pirate Roberts" to operate the site anonymously. Ross meets Julia, a student who becomes his lover and partner in crime. As Silk Road gains popularity, Ross makes millions by facilitating the sale of illegal items such as drugs, weapons, and identity information. However, when a Gawker article about Silk Road brings unwanted attention, law enforcement begins investigating the darknet marketplace. DEA agent Rick Bowden, who has been reassigned to the cybercrimes unit after rehab, is tasked with investigating Silk Road. He enlists an informant to teach him about darknet activities, leading to clashes with fellow agents and strains in his personal life. As Silk Road thrives, Ross becomes increasingly isolated from Julia and his friend Max, who express concerns about his illegal activities. Ross, operating under the alias Dread Pirate Roberts, becomes a sensation on Silk Road and engages in various interactions with sellers and buyers on the website, all while maintaining a sense of invincibility. DEA agents, including Rick, work tirelessly to track down the owner of Silk Road, leading to a sting operation orchestrated by Rick. The film portrays Ross's eventual arrest and the dismantling of Silk Road. Throughout the movie, the personal struggles of both Ross and Rick are depicted, shedding light on their motivations and challenges. Ross's arrest has a profound impact on his relationships and the lives of those affected by Silk Road. The film touches on themes of hubris, greed, and the clash between individual freedom and law enforcement. It also explores the complexities of Ross's character and the blurred lines between the moralities of the law and the actions of its enforcers. As the Silk Road gains notoriety, law enforcement agencies become determined to shut it down. Rick Bowden, a DEA agent, takes on the case and begins investigating Ulbricht. Bowden is portrayed as a dedicated law enforcement officer who is intent on bringing down Silk Road and its elusive operator. Ross Ulbricht continues to manage Silk Road, amassing a substantial fortune through the illicit marketplace. He forms alliances and confronts threats from both law enforcement and rival criminals within the dark web. In the end, Ross Ulbricht is arrested and faces the legal consequences of his actions, highlighting the significant impact of Silk Road on the world of online criminal enterprises and the ongoing debate about the boundaries of individual liberty and government intervention in the digital age. The film reaches its climax when Ulbricht is finally apprehended by law enforcement, and his true identity is revealed. He is arrested and faces a lengthy trial for drug trafficking, money laundering, and other charges related to Silk Road. During the trial, Ulbricht's defense team argues that he was framed and that he is not the true Dread Pirate Roberts. == Cast == Jason Clarke as Richard "Rick" Bowden aka "Jurassic Narc" Nick Robinson as Ross Ulbricht Alexandra Shipp as Julia Vie Jimmi Simpson as Chris Tarbell Paul Walter Hauser as Curtis Clark Green Darrell Britt-Gibson as Rayford Katie Aselton as Sandy Bowden Lexi Rabe as Edie Bowden Daniel David Stewart as Max Will Ropp as Shields Jennifer Yun as FBI Agent Kim Yum David DeLao as Johnny Marales Raleigh Cain as Callie == Production == In January 2019, it was announced Jason Clarke and Nick Robinson had joined the cast of the film, with Tiller Russell directing from a screenplay he wrote. In May 2019, Cole Sprouse, Darrell Britt-Gibson and Jimmi Simpson joined the cast of the film. In June 2019, Paul Walter Hauser, Katie Aselton and Lexi Rabe joined the cast of the film. That same month, Daniel David Stewart joined the cast of the film, replacing Sprouse. Principal photography began in June 2019 in Albuquerque, New Mexico. == Release == It was scheduled to have its world premiere at the Tribeca Film Festival on April 16, 2020. However, the festival was postponed due to the COVID-19 pandemic. In December 2020, Lionsgate acquired U.S. distribution rights to the film, and set it for a February 19, 2021, release. === Reception === Review aggregator Rotten Tomatoes gives the film a 52% approval rating based on 64 reviews, with an average rating of 5.60/10. The website's critics consensus reads: "Silk Road draws intriguing parallels between its oppositional main characters, but doesn't do quite enough to develop the story surrounding them." According to Metacritic, which sampled 11 critics and calculated a weighted average score of 41 out of 100, the film received "mixed or average reviews". == See also == Deep Web (film) Ross Ulbricht == References == == External links == Silk Road at IMDb

Silk Road is a 2021 American crime thriller film, written for the screen and directed by Tiller Russell based on the Rolling Stone article "Dead End on Silk Road: Internet Crime Kingpin Ross Ulbricht's Big Fall" by David Kushner. The film stars Jason Clarke, Nick Robinson, Alexandra Shipp, Jimmi Simpson, Paul Walter Hauser, Darrell Britt-Gibson, and Will Ropp. It is based on the true story of Ross Ulbricht who develops a website on the darknet, an act which attracts the attention of the FBI and DEA who send in federal agent Richard "Rick" Bowden, a fictional composite of real life DEA Agent Carl Force and US Secret Service Special Agent Shaun Bridges, both of whom were convicted of felonies related to theft of assets in the investigation of Ulbricht, to bring down Ross' empire. Silk Road was released in the United States on February 19, 2021 by Lionsgate.

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Silk Road (marketplace) (wikipedia)

Silk Road was an online black market and the first modern darknet market. It was launched in 2011 by its American founder Ross Ulbricht under the pseudonym "Dread Pirate Roberts." As part of the dark web, Silk Road operated as a hidden service on the Tor network, allowing users to buy and sell products and services between each other anonymously. All transactions were conducted with bitcoin, a cryptocurrency which aided in protecting user identities. The website was known for its illegal drug marketplace, among other illegal and legal product listings. Between February 2011 and July 2013, the site facilitated sales amounting to 9,519,664 Bitcoins. In October 2013, the Federal Bureau of Investigation (FBI) shut down the Silk Road website and arrested Ulbricht. Silk Road 2.0 came online the next month, run by other administrators of the former site, but was shut down the following year as part of Operation Onymous. In 2015, Ulbricht was convicted in federal court for multiple charges related to operating Silk Road and was given two life sentences without possibility of parole. == History == === Operations === The website was launched in February 2011; development had begun six months prior. The name "Silk Road" comes from a historical network of trade routes started during the Han Dynasty (206 BCE – 220 CE) between Europe, India, China, and many other countries on the Afro-Eurasian landmass. Silk Road was operated by the pseudonymous "Dread Pirate Roberts" (named after the fictional character from The Princess Bride), who was known for espousing libertarian ideals and criticizing regulation. Two other individuals were also closely involved in the site's growth and success, known as Variety Jones and Smedley. In June 2011, Gawker published an article about the site which led to an increase in notoriety and website traffic. U.S. Senator Charles Schumer asked federal law enforcement authorities to shut it down, including the Drug Enforcement Administration (DEA) and Department of Justice. In May 2013, Silk Road was taken down for a short period of time by a sustained DDoS attack. On 23 June 2013, it was first reported that the DEA seized 11.02 bitcoins, then worth a total of $814, which the media suspected was a result of a Silk Road honeypot sting. The FBI has claimed that the real IP address of the Silk Road server was found via data leaked directly from the site's CAPTCHA and it was located in Reykjavík, Iceland. IT security experts have doubted the FBI's claims because technical evidence suggests that no misconfiguration that could cause the specific leak was present at the time. Henry Farrell, an associate professor of political science and international affairs at George Washington University, analyzed Silk Road in an essay for Aeon in 2015. He noted that Ulbricht created the marketplace to function without government oversight but found it difficult to verify anonymous transactions. To sustain a steady stream of revenue, he started increasing oversight to ensure low transaction costs. To do this, he added measures to ensure trustworthiness with implementation of an automated escrow payment system and automated review system. === Arrest and trial of Ross Ulbricht === Due, in part, to off-duty research conducted by IRS Criminal Investigation Special Agent Gary Alford, Ross Ulbricht was alleged by the FBI to be the founder and owner of Silk Road and the person behind the pseudonym "Dread Pirate Roberts" (DPR). Alford searched for any mentions of the .onion URL or .tor address, stating that someone might have advertised or suggested the marketplace on Google. The first mention of the website was by a user named "altoid." Further searching into this altoid profile led him to a post about an open position that told interested applicants to contact what was Ross Ulbricht's personal email. He was arrested on 1 October 2013 in San Francisco in Glen Park Library, a branch of the San Francisco Public Library. During the arrest, the FBI seized Ulbricht's laptop which he was using to connect to the servers and manage the marketplace. Ulbricht was indicted on charges of engaging in a continuing criminal enterprise, distributing narcotics, distributing narcotics by means of the Internet, and four conspiracy charges related to distribution of narcotics, computer hacking, money laundering, and false identity documents. He was separately indicted for a single murder-for-hire charge. Prosecutors alleged that Ulbricht paid $730,000 to others to commit the murders, although none of the murders actually occurred. Ulbricht ultimately was not prosecuted for any of the alleged murder attempts. The FBI initially seized 26,000 bitcoins from accounts on Silk Road, worth approximately $3.6 million at the time. An FBI spokesperson said that the agency would hold the bitcoins until Ulbricht's trial finished, after which the bitcoins would be liquidated. In October 2013, the FBI reported that it had seized 144,000 bitcoins, worth $28.5 million, and that the bitcoins belonged to Ulbricht. On 27 June 2014, the U.S. Marshals Service sold 29,657 bitcoins in 10 blocks in an online auction, estimated to be worth $18 million at contemporary rates and only about a quarter of the seized bitcoins. Another 144,342 bitcoins were kept which had been found on Ulbricht's computer, roughly $87 million. Tim Draper bought the bitcoins at the auction with an estimated worth of $17 million, to lend them to a bitcoin start-up called Vaurum which is working in developing economies of emerging markets. Ulbricht's trial began on 13 January 2015 in federal court in Manhattan. At the start of the trial, Ulbricht admitted to founding the Silk Road website, but claimed to have transferred control of the site to other people soon after he founded it. Ulbricht's lawyers contended that Dread Pirate Roberts was really Mark Karpelès, and that Karpelès set up Ulbricht as a fall guy. However, Judge Katherine B. Forrest ruled that any speculative statements regarding whether Karpelès or anyone else ran Silk Road would not be allowed, and statements already made would be stricken from the record. In the second week of the trial, prosecutors presented documents and chat logs from Ulbricht's computer that, they said, demonstrated how Ulbricht had administered the site for many months, which contradicted the defense's claim that Ulbricht had relinquished control of Silk Road. Ulbricht's attorney suggested that the documents and chat logs were planted there by way of BitTorrent, which was running on Ulbricht's computer at the time of his arrest. On 4 February 2015, the jury convicted Ulbricht of seven charges, including charges of engaging in a continuing criminal enterprise, narcotics trafficking, money laundering, and computer hacking. The continuing criminal enterprise charge has a minimum sentence of 20 years. The amount of narcotics distributed also triggered an additional 10-year minimum. The government also accused Ulbricht of paying for the murders of at least five people, but there is no evidence that the murders were actually carried out, and the accusations never became formal charges against Ulbricht. During the trial, Judge Forrest received death threats. Users of an underground site called The Hidden Wiki posted her personal information there, including her address and Social Security number. Ulbricht's lawyer Joshua Dratel said that he and his client "obviously, and as strongly as possible, condemn" the anonymous postings against the judge. "They do not in any way have anything to do with Ross Ulbricht or anyone associated with him or reflect his views or those of anyone associated with him," Dratel said. In late March 2015, a criminal complaint issued by the United States District Court for the Northern District of California led to the arrest of two former federal agents who had worked undercover in the Baltimore Silk Road investigation of Ulbricht, former Drug Enforcement Administration agent Carl Mark Force IV and Secret Service agent Shaun Bridges. The agents are alleged to have kept funds that Ulbricht transferred to them in exchange for purported information about the investigation. The agents were charged with wire fraud and money laundering. In late November 2016, Ulbricht's lawyers brought forward a case on a third DEA agent, who they claim was leaking information about the investigation and tampered with evidence to omit chat logs showing conversations with him. In a letter to Judge Forrest before his sentencing, Ulbricht stated that his actions through Silk Road were committed through libertarian idealism and that "Silk Road was supposed to be about giving people the freedom to make their own choices" and admitted that he made a "terrible mistake" that "ruined his life." On 29 May 2015, Ulbricht was given five sentences to be served concurrently, including two of life imprisonment without the possibility of parole. He was also ordered to forfeit $183 million. Ulbricht's lawyer Joshua Dratel said that he would appeal the sentencing and the original guilty verdict. On 31 May 2017, the United States Court of Appeals for the Second Circuit denied Ulbricht's appeal, and affirmed the judgment of conviction and life sentence, in a written opinion authored by Gerard E. Lynch, United States circuit judge. The Supreme Court declined to review the case. === Other trials === In February 2013, an Australian cocaine and MDMA ("ecstasy") dealer became the first person to be convicted of crimes directly related to Silk Road, after authorities intercepted drugs that he was importing through the mail, searched his premises, and discovered his Silk Road alias in an image file on his personal computer. Australian police and the DEA have targeted Silk Road users and made arrests, albeit with limited success at reaching convictions. In December 2013, a New Zealand man was sentenced to two years and four months in jail after being convicted of importing 15 grams of methamphetamine that he had bought on Silk Road. 23-year-old Dutch drug dealer Cornelis Jan "Maikel" Slomp pled guilty to large-scale selling of drugs through the Silk Road website, and was sentenced in Chicago to 10 years in prison on 29 May 2015 with his attorney, Paul Petruzzi, present. Dealer Steven Sadler was sentenced to five years in prison. There have been over 130 other arrests connected with Silk Road, although some of these arrests may not be directly related to Silk Road, and may not be public information for legal reasons. === Later seizures === On 3 November 2020, after years of inactivity, observers of the bitcoin blockchain detected that two transactions totaling 69,370 bitcoin and bitcoin cash, worth approximately $1 billion in total at the time of transfer, had been made from a bitcoin address associated with the Silk Road. At the time of transfer, it was worth 58 times its value in 2015. It was subsequently revealed that the transfer had been made by the United States government in a civil forfeiture action. According to a press release by the U.S. Attorney's Office of the Northern District of California, the bitcoin wallet belonged to an "Individual X" who had originally acquired the bitcoins by hacking the Silk Road. == Products == In March 2013, the site had 10,000 products for sale by vendors, 70% of which were drugs. Drugs were grouped under the headings stimulants, psychedelics, prescription, precursors, other, opioids, ecstasy, dissociatives, and steroids/PEDs. Fake driver's licenses were also offered for sale. The site's terms of service prohibited the sale of certain items. When the Silk Road marketplace first began, the creator and administrators instituted terms of service that prohibited the sale of anything whose purpose was to "harm or defraud." This included child pornography, stolen credit cards, assassinations, and weapons of any type; other darknet markets such as Black Market Reloaded gained user notoriety because they were not as restrictive on these items as the Silk Road incarnations were. There were also legal goods and services for sale, such as apparel, art, books, cigarettes, erotica, jewellery, and writing services. A sister site, called "The Armoury," sold weapons (primarily firearms) during 2012, but was shut down, due to a lack of demand. The Silk Road offered over 24,400 products related to drugs for sale and an infrastructure that made these transactions. The official sellers guide stated the prohibition of any sale of goods that were meant for harm or fraud, but allowed for prescription drugs, pornography, and counterfeit documents. Only users of Tor could access the Silk Road. Buyers were able to leave reviews of sellers' products on the site and in an associated forum, where crowdsourcing provided information about the best sellers and worst scammers. Most products were delivered through the mail, with the site's seller's guide instructing sellers how to vacuum-seal their products to escape detection. == Sales == Silk Road provided goods and services to over 100,000 buyers. Over the 2+1⁄2 years in which the website was in operation, it generated $183 million in sales and $13 million in commissions, based on the value of bitcoin at the time of transactions. Due to the significant rise in bitcoin value over that period, the revenue and commission are also sometimes reported as $1.2 billion and $80 million, respectively. Initially there were a limited number of new seller accounts available; new sellers had to purchase an account in an auction. Later, a fixed fee was charged for each new seller account. Buyers and sellers conducted all transactions with bitcoins (BTC), a cryptocurrency that provides a certain degree of anonymity. Silk Road held buyers' bitcoins in escrow until the order had been received and a hedging mechanism allowed sellers to opt for the value of bitcoins held in escrow to be fixed to their value in US$ at the time of the sale to mitigate against Bitcoin's volatility. Any changes in the price of bitcoins during transit were covered by Dread Pirate Roberts. The complaint published when Ulbricht was arrested included information the FBI gained from a system image of the Silk Road server collected on 23 July 2013. It noted that, "From February 6, 2011 to July 23, 2013 there were approximately 1,229,465 transactions completed on the site. The total revenue generated from these sales was 9,519,664 Bitcoins, and the total commissions collected by Silk Road from the sales amounted to 614,305 Bitcoins. According to the government, total sales were equivalent to roughly $1.2 billion and involved 146,946 buyers and 3,877 vendors. According to information users provided upon registering, 30 percent were from the United States, 27 percent chose to be "undeclared," and beyond that, in descending order of prevalence: the United Kingdom, Australia, Germany, Canada, Sweden, France, Russia, Italy, and the Netherlands. During the 60-day period from 24 May to 23 July, there were 1,217,218 messages sent over Silk Road's private messaging system. == Similar sites == The Farmer's Market was a Tor site similar to Silk Road, but which did not use bitcoins. It has been considered a 'proto-Silk Road' but the use of payment services such as PayPal and Western Union allowed law enforcement to trace payments and it was subsequently shut down by the FBI in 2012. Other sites already existed when Silk Road was shut down and The Guardian predicted that these would take over the market that Silk Road previously dominated. Atlantis was founded in March 2013 and closed six months later, while Project Black Flag closed in October 2013; both websites stole their users' bitcoins. In October 2013, Black Market Reloaded closed temporarily after its source code was leaked. The market shares of various Silk Road successor sites were described by The Economist in May 2015. == Book club == Silk Road had a Tor-based book club that continued to operate following the initial site's closure and even following the arrest of one of its members. Reading material included conspiracy theories and computer hacking. Some of the titles included mainstream books as well as books such as The Anarchist Cookbook and Defeating Electromagnetic Door Locks. Most of the titles on this book club were pirated. This book club still exists as a private Tor-based chatroom. == Direct successors == === Silk Road 2.0 === On 6 November 2013, administrators from the closed Silk Road relaunched the site, led by a new pseudonymous Dread Pirate Roberts, and dubbed it "Silk Road 2.0." It recreated the original site's setup and promised improved security. The new DPR took the precaution of distributing encrypted copies of the site's source code to allow the site to be quickly recreated in the event of another shutdown. On 20 December 2013, it was announced that three alleged Silk Road 2.0 administrators had been arrested; two of these suspects, Andrew Michael Jones and Gary Davis, were named as the administrators "Inigo" and "Libertas" who had continued their work on Silk Road 2.0. Around this time, the new Dread Pirate Roberts abruptly surrendered control of the site and froze its activity, including its escrow system. A new temporary administrator under the screenname "Defcon" took over and promised to bring the site back to working order. On 13 February 2014, Defcon announced that Silk Road 2.0's escrow accounts had been compromised through a vulnerability in Bitcoin protocol called "transaction malleability." While the site remained online, all the bitcoins in its escrow accounts, valued at $2.7 million, were reported stolen. It was later reported that the vulnerability was in the site's "Refresh Deposits" function, and that the Silk Road administrators had used their commissions on sales since 15 February to refund users who lost money, with 50 percent of the hack victims being completely repaid as of 8 April. On 6 November 2014, authorities with the Federal Bureau of Investigation, Europol, and Eurojust announced the arrest of Blake Benthall, allegedly the owner and operator of Silk Road 2.0 under the pseudonym "Defcon," the previous day in San Francisco as part of Operation Onymous. The creator of the relaunched website—an English computer programmer named Thomas White—was also arrested in the course of the shutdown, but his arrest was not made public until 2019 after he pled guilty to charges stemming from running the website and was sentenced to five years in prison. Among the charges White admitted to was creating child pornography, and chat logs recovered by police showed White discussing the possibility of launching a website to host such material. === Others === Following the closure of Silk Road 2.0 in November 2014, Diabolus Market renamed itself to 'Silk Road 3 Reloaded' in order to capitalize on the brand. In January 2015, Silk Road Reloaded launched on I2P with multiple cryptocurrency support and similar listing restrictions to the original Silk Road market. This website is also defunct. == Advocates of dark web drug sales & Ulbricht == Meghan Ralston, a former harm reduction manager for the Drug Policy Alliance, was quoted as saying that the Silk Road was "a peaceable alternative to the often deadly violence so commonly associated with the global drug war, and street drug transactions, in particular." Proponents of the Silk Road and similar sites argue that buying illegal narcotics from the safety of your home is better than buying them in person from criminals on the streets. == Media == Deep Web (2015) – A film by director/screenwriter Alex Winter based on Silk Road which gives the inside story of the arrest of Ross Ulbricht Silk Road: Drugs, Death, and the Dark Web. A&E Television, 2018. Casefile True Crime Podcast – Case 76: Silk Road (Parts 1, 2, 3) - aired 10, 17, 24 February 2018 American Kingpin - A New York Times best-selling biography, by Nick Bilton, of Ross Ulbricht's life prior to, during, and after the Silk Road Silk Road – A 2021 film starring Jason Clarke, and Nick Robinson as Ross Ulbricht == See also == Agorism Crypto-anarchism James Zhong OpenBazaar War on drugs == References == "Ross Ulbricht, the Creator and Owner of the Silk Road Website, Found Guilty in Manhattan Federal Court on All Counts — FBI". www.fbi.gov. Retrieved 21 April 2023. Christin, Nicolas (13 May 2013). "Traveling the silk road". Proceedings of the 22nd international conference on World Wide Web. WWW '13. New York, NY, USA: Association for Computing Machinery. pp. 213–224. doi:10.1145/2488388.2488408. ISBN 978-1-4503-2035-1. S2CID 4534396. == External links == "'Silk Road' website called the Amazon of heroin, cocaine." ABC Action News. YouTube. 10 June 2011 "Silk Road: Theory & Practice" "United States of America v. Ross William Ulbricht" Grand Jury Indictment, District of Maryland (1 October 2013) "United States of America v. Ross William Ulbricht" Trial Transcript Archived early advertisement page for Silk Road

Silk Road was an online black market and the first modern darknet market. It was launched in 2011 by its American founder Ross Ulbricht under the pseudonym "Dread Pirate Roberts." As part of the dark web, Silk Road operated as a hidden service on the Tor network, allowing users to buy and sell products and services between each other anonymously. All transactions were conducted with bitcoin, a cryptocurrency which aided in protecting user identities. The website was known for its illegal drug marketplace, among other illegal and legal product listings. Between February 2011 and July 2013, the site facilitated sales amounting to 9,519,664 Bitcoins. In October 2013, the Federal Bureau of Investigation (FBI) shut down the Silk Road website and arrested Ulbricht. Silk Road 2.0 came online the next month, run by other administrators of the former site, but was shut down the following year as part of Operation Onymous. In 2015, Ulbricht was convicted in federal court for multiple charges related to operating Silk Road and was given two life sentences without possibility of parole.

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Black Market (Rick Ross album) (wikipedia)

Black Market is the eighth studio album by American rapper Rick Ross. The album was released on December 4, 2015, by Maybach Music Group and Def Jam Recordings. The album features guest appearances from John Legend, CeeLo Green, Nas, DJ Premier, Mariah Carey, Mary J. Blige, Chris Brown, Future and The-Dream. == Background == In November 2015, in an interview with Billboard, he spoke about the album, saying: "You know, this album is, I feel like, most definitely gonna be a Rozay on a higher, intellectual level, just discussing a different array of things. When you listen to records like "Foreclosure," that's like me sitting in a room by myself just rapping about things that's running across my mind and things that have been bothering me. And during my incarceration, that was the type of music I created. Just in that short moment of time, I really just sat there... I'm a muthafucka that flies six million miles a year and just to halt one day, out of the blue, for three weeks? It's just, "Woah." There's a lot of shit that I wrote and a lot of shit that I thought about. I came back out and scrapped a lot of music and I recorded some dope songs, but my first day home I recorded six records. So that's why I was able to put out the Black Dollar record and have been releasing a slew of freestyles, just feeding the fans and everybody that's been asking for that Rozay music." == Singles == The album's lead single, "Foreclosures" was released on September 23, 2015. The album's second single, "Sorry" was released on October 9, 2015. The song features guest vocals from American recording artist Chris Brown and is produced by Scott Storch. On November 12, 2015, the music video was released for "Sorry". == Critical reception == Black Market received generally positive reviews from music critics. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 61, based on 9 reviews, which indicates "generally positive reviews". David Jeffries of AllMusic said, "This Miami Don remains an unapologetic and indefensible brute -- and he says as much on this very LP -- but this rough, honest, and ambitious work is like his Raging Bull, taking the listener on a compelling, dirty journey that's also a connectable character study, and then letting some slick Chris Brown ("Sorry") and Future ("D.O.P.E") features play while the credits roll." Scott Glaysher of HipHopDX said, "All in all, Black Market does its job. It doesn’t hit as hard as some previous albums, but it surely proves just how good Rick Ross can be as a songwriter and collaborator. It also proves how sharp he has become as a rapper. There may not be a thundering single that the album is built around, but, for the most part, Ross’s consistency fills that gap quite nicely." Julian Kimble of Pitchfork Media stated, "The motivated, slightly weary Ross heard on Black Market—which has no MMG features—is a better fit for the moment than the bulletproof supervillain of old. Ross has proven his resilience in the past; maybe carefully controlled doses of reality are just what he needs to move forward." == Commercial performance == In the United States, the album debuted at number 6 on the Billboard 200, with 65,000 album-equivalent units (54,000 copies of pure sales) in its first week. == Track listing == Notes ^[a] signifies a co-producer ^[b] signifies an additional producer "Silk Road" features additional vocals from Teedra Moses. "Peace Sign" features additional vocals from Red Café and Jeremih. "Foreclosures" features additional vocals from Kenneth Bartolomei. == Charts == == References ==

Black Market is the eighth studio album by American rapper Rick Ross. The album was released on December 4, 2015, by Maybach Music Group and Def Jam Recordings. The album features guest appearances from John Legend, CeeLo Green, Nas, DJ Premier, Mariah Carey, Mary J. Blige, Chris Brown, Future and The-Dream.

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Silk Road (wikipedia)

The Silk Road (Chinese: 丝绸之路) was a network of Eurasian trade routes active from the second century BCE until the mid-15th century. Spanning over 6,400 kilometers (4,000 miles), it played a central role in facilitating economic, cultural, political, and religious interactions between the East and West. The name "Silk Road," first coined in the late 19th century, has fallen into disuse among some modern historians in favor of Silk Routes, on the grounds that it more accurately describes the intricate web of land and sea routes connecting Central, East, South, Southeast, and West Asia as well as East Africa and Southern Europe. The Silk Road derives its name from the highly lucrative trade of silk textiles that were primarily produced in China. The network began with the Han dynasty's expansion into Central Asia around 114 BCE through the missions and explorations of the Chinese imperial envoy Zhang Qian, which brought the region under unified control. The Chinese took great interest in the security of their trade products, and extended the Great Wall of China to ensure the protection of the trade route. By the early first century CE, Chinese silk was widely sought-after in Rome, Egypt, and Greece. Other lucrative commodities from the East included tea, dyes, perfumes, and porcelain; among Western exports were horses, camels, honey, wine, and gold. Aside from generating substantial wealth for emerging mercantile classes, the proliferation of goods such as paper and gunpowder greatly altered the trajectory of various realms, if not world history. During its more than 1,500 years of existence, the Silk Road endured the rise and fall of numerous empires and major events such as the Black Death and the Mongol conquests. As a highly decentralized network, security was sparse. Travelers faced constant threats of banditry and nomadic raiders, and long expanses of inhospitable terrain. Few individuals crossed the entirety of the Silk Road, instead relying on a succession of middlemen based at various stopping points along the way. In addition to goods, the network facilitated an unprecedented exchange of ideas, religions (especially Buddhism), philosophies, and scientific discoveries, many of which were syncretised or reshaped by the societies that encountered them. Likewise, a wide variety of people used the routes. Diseases such as plague also spread along the Silk Road, possibly contributing to the Black Death. Despite repeatedly surviving many geopolitical changes and disruptions, the Ottoman Empire and other gunpowder empires expanded efforts to gain greater control of it from 1453 onwards. This prompted European efforts to seek alternative routes to trading with the gunpowder empires, as well as other nations and communities, while also gaining leverage over them in turn after the Ottomans increased their usage of land-based trade, thereby ushering in the Age of Discovery, European colonialism, and a more intensified process of globalization, which had arguably begun with the Silk Road. In the 21st century, the name "New Silk Road" is used to describe several large infrastructure projects along many of the historic trade routes; among the best known include the Eurasian Land Bridge and the Chinese Belt and Road Initiative (BRI). In June 2014, UNESCO designated the Chang'an-Tianshan corridor of the Silk Road as a World Heritage Site, while the Indian portion remains on the tentative site list. == Name == The Silk Road derives its name from the lucrative trade in silk, first developed in China, and a major reason for the connection of trade routes into an extensive transcontinental network. It derives from the German term Seidenstraße (literally "Silk Road") and was first popularized in 1877 by Ferdinand von Richthofen, who made seven expeditions to China from 1868 to 1872. However, the term itself had been in use in decades prior to that. The alternative translation "Silk Route" is also used occasionally. Although the term was coined in the 19th century, it did not gain widespread acceptance in academia or popularity among the public until the 20th century. The first book entitled The Silk Road was by Swedish geographer Sven Hedin in 1938. The use of the term 'Silk Road' is not without its detractors. For instance, Warwick Ball contends that the maritime spice trade with India and Arabia was far more consequential for the economy of the Roman Empire than the silk trade with China, which at sea was conducted mostly through India and on land was handled by numerous intermediaries such as the Sogdians. Going as far as to call the whole thing a "myth" of modern academia, Ball argues that there was no coherent overland trade system and no free movement of goods from East Asia to the West until the period of the Mongol Empire. He notes that traditional authors discussing east–west trade such as Marco Polo and Edward Gibbon never labelled any route a "silk" one in particular. The southern stretches of the Silk Road, from Khotan (Xinjiang) to Eastern China, were first used for jade and not silk, as long as 5000 BCE, and are still in use for this purpose. The term "Jade Road" would have been more appropriate than "Silk Road" had it not been for the far larger and geographically wider nature of the silk trade; the term is in current use in China. == Routes == The Silk Road consisted of several routes. As it extended westwards from the ancient commercial centres of China, the overland, intercontinental Silk Road divided into northern and southern routes bypassing the Taklamakan Desert and Lop Nur. Merchants along these routes were involved in "relay trade" in which goods changed "hands many times before reaching their final destinations." === Northern route === The northern route started at Chang'an (now called Xi'an), an ancient capital of China that was moved further east during the Later Han to Luoyang. The route was defined around the 1st century BCE when Han Wudi put an end to harassment by nomadic tribes. The northern route travelled northwest through the Chinese province of Gansu from Shaanxi Province and split into three further routes, two of them following the mountain ranges to the north and south of the Taklamakan Desert to rejoin at Kashgar, and the other going north of the Tian Shan mountains through Turpan, Talgar, and Almaty (in what is now southeast Kazakhstan). The routes split again west of Kashgar, with a southern branch heading down the Alai Valley towards Termez (in modern Uzbekistan) and Balkh (Afghanistan), while the other travelled through Kokand in the Fergana Valley (in present-day eastern Uzbekistan) and then west across the Karakum Desert. Both routes joined the main southern route before reaching ancient Merv, Turkmenistan. Another branch of the northern route turned northwest past the Aral Sea and north of the Caspian Sea, then and on to the Black Sea. A route for caravans, the northern Silk Road brought to China many goods such as "dates, saffron powder and pistachio nuts from Persia; frankincense, aloes and myrrh from Somalia; sandalwood from India; glass bottles from Egypt, and other expensive and desirable goods from other parts of the world." In exchange, the caravans sent back bolts of silk brocade, lacquer-ware, and porcelain. === Southern route === The southern route or Karakoram route was mainly a single route from China through the Karakoram mountains, where it persists in modern times as the Karakoram Highway, a paved road that connects Pakistan and China. It then set off westwards, but with southward spurs so travelers could complete the journey by sea from various points. Crossing the high mountains, it passed through northern Pakistan, over the Hindu Kush mountains, and into Afghanistan, rejoining the northern route near Merv, Turkmenistan. From Merv, it followed a nearly straight line west through mountainous northern Iran, Mesopotamia, and the northern tip of the Syrian Desert to the Levant, where Mediterranean trading ships plied regular routes to Italy, while land routes went either north through Anatolia or south to North Africa. Another branch road travelled from Herat through Susa to Charax Spasinu at the head of the Persian Gulf and across to Petra and on to Alexandria and other eastern Mediterranean ports from where ships carried the cargoes to Rome. === Southwestern route === The southwestern route is believed to be the Ganges/Brahmaputra Delta, which has been the subject of international interest for over two millennia. Strabo, the 1st-century Roman writer, mentions the deltaic lands: "Regarding merchants who now sail from Egypt ... as far as the Ganges, they are only private citizens." His comments are interesting as Roman beads and other materials are being found at Wari-Bateshwar ruins, the ancient city with roots from much earlier, before the Bronze Age, presently being slowly excavated beside the Old Brahmaputra in Bangladesh. Ptolemy's map of the Ganges Delta, a remarkably accurate effort, showed that his informants knew all about the course of the Brahmaputra River, crossing through the Himalayas then bending westward to its source in Tibet. It is doubtless that this delta was a major international trading center, almost certainly from much earlier than the Common Era. Gemstones and other merchandise from Thailand and Java were traded in the delta and through it. Chinese archaeological writer Bin Yang and some earlier writers and archaeologists, such as Janice Stargardt, strongly suggest this route of international trade as Sichuan–Yunnan–Burma–Bangladesh route. According to Bin Yang, especially from the 12th century, the route was used to ship bullion from Yunnan (gold and silver are among the minerals in which Yunnan is rich), through northern Burma, into modern Bangladesh, making use of the ancient route, known as the 'Ledo' route. The emerging evidence of the ancient cities of Bangladesh, in particular Wari-Bateshwar ruins, Mahasthangarh, Bhitagarh, Bikrampur, Egarasindhur, and Sonargaon, are believed to be the international trade centers in this route. === Maritime route === The Maritime Silk Road or Maritime Silk Route is the maritime section of the historic Silk Road that connected Southeast Asia, East Asia, the Indian subcontinent, the Arabian Peninsula, eastern Africa, and Europe. It began by the 2nd century BCE and flourished until the 15th century CE. The Maritime Silk Road was primarily established and operated by Austronesian sailors in Southeast Asia who sailed large long-distance ocean-going sewn-plank and lashed‑lug trade ships.: 11 The route was also utilized by the dhows of the Persian and Arab traders in the Arabian Sea and beyond,: 13 and the Tamil merchants in South Asia.: 13 China also started building their own trade ships (chuán) and followed the routes in the later period, from the 10th to the 15th centuries CE. The network followed the footsteps of older Austronesian jade maritime networks in Southeast Asia, as well as the maritime spice networks between Southeast Asia and South Asia, and the West Asian maritime networks in the Arabian Sea and beyond, coinciding with these ancient maritime trade roads by the current era. Austronesian thalassocracies controlled the flow of trade in the eastern regions of the Maritime Silk Road, especially the polities around the straits of Malacca and Bangka, the Malay Peninsula, and the Mekong Delta; through which passed the main routes of the Austronesian trade ships to Giao Chỉ (in the Tonkin Gulf) and Guangzhou (southern China), the endpoints (later also including Quanzhou by the 10th century CE). Secondary routes also passed through the coastlines of the Gulf of Thailand; as well as through the Java Sea, Celebes Sea, Banda Sea, and the Sulu Sea, reconnecting with the main route through the northern Philippines and Taiwan. The secondary routes also continue onward to the East China Sea and the Yellow Sea for a limited extent. The main route of the western regions of the Maritime Silk Road directly crosses the Indian Ocean from the northern tip of Sumatra (or through the Sunda Strait) to Sri Lanka, southern India and Bangladesh, and the Maldives. It branches from here into routes through the Arabian Sea entering the Gulf of Oman (into the Persian Gulf), and the Gulf of Aden (into the Red Sea). Secondary routes also pass through the coastlines of the Bay of Bengal, the Arabian Sea, and southwards along the coast of East Africa to Zanzibar, the Comoros, Madagascar, and the Seychelles. The term "Maritime Silk Road" is a modern name, acquired from its similarity to the overland Silk Road. Like the overland routes, the ancient maritime routes through Southeast Asia and the Indian Ocean had no particular name for the majority of its very long history. Despite the modern name, the Maritime Silk Road involved exchanges in a wide variety of goods over a very wide region, not just silk or Asian exports. It differed significantly in several aspects from the overland Silk Road, and thus should not be viewed as a mere extension of it. Traders traveling through the Maritime Silk Road could span the entire distance of the maritime routes, instead of through regional relays as with the overland route. Ships could carry far larger amounts of goods, creating greater economic impact with each exchange. Goods carried by the ships also differed from goods carried by caravans. Traders on the maritime route faced different perils like weather and piracy, but they were not affected by political instability and could simply avoid areas in conflict. == History == === Precursors === ==== Chinese and Central Asian contacts (2nd millennium BCE) ==== Central Eurasia has been known from ancient times for its horse riding and horse breeding communities, and the overland Steppe Route across the northern steppes of Central Eurasia was in use long before that of the Silk Road. Archeological sites, such as the Berel burial ground in Kazakhstan, confirmed that the nomadic Arimaspians were not only breeding horses for trade but also produced great craftsmen able to propagate exquisite art pieces along the Silk Road. From the 2nd millennium BCE, nephrite jade was being traded from mines in the region of Yarkand and Khotan to China. Significantly, these mines were not very far from the lapis lazuli and spinel ("Balas Ruby") mines in Badakhshan, and, although separated by the formidable Pamir Mountains, routes across them were apparently in use from very early times. Genetic study of the Tarim mummies, found in the Tarim Basin, in the area of Loulan located along the Silk Road 200 kilometres (124 miles) east of Yingpan, dating to as early as 1600 BCE, suggest very ancient contacts between East and West. These mummified remains may have been of people who spoke Indo-European languages, which remained in use in the Tarim Basin, in the modern day Xinjiang region, until replaced by Turkic influences from the Xiongnu culture to the north and by Chinese influences from the eastern Han dynasty, who spoke a Sino-Tibetan language. Some remnants of what was probably Chinese silk dating from 1070 BCE have been found in Ancient Egypt. The Great Oasis cities of Central Asia played a crucial role in the effective functioning of the Silk Road trade. The originating source seems sufficiently reliable, but silk degrades very rapidly, so it cannot be verified whether it was cultivated silk (which almost certainly came from China) or a type of wild silk, which might have come from the Mediterranean or Middle East. Following contacts between Metropolitan China and nomadic western border territories in the 8th century BCE, gold was introduced from Central Asia, and Chinese jade carvers began to make imitation designs of the steppes, adopting the Scythian-style animal art of the steppes (depictions of animals locked in combat). This style is particularly reflected in the rectangular belt plaques made of gold and bronze, with other versions in jade and steatite. An elite burial near Stuttgart, Germany, dated to the 6th century BCE, was excavated and found to have not only Greek bronzes but also Chinese silks. Similar animal-shaped pieces of art and wrestler motifs on belts have been found in Scythian grave sites stretching from the Black Sea region all the way to Warring States era archaeological sites in Inner Mongolia (at Aluchaideng) and Shaanxi (at Keshengzhuang) in China. The expansion of Scythian cultures, stretching from the Hungarian plain and the Carpathian Mountains to the Chinese Gansu Corridor, and linking the Middle East with Northern India and the Punjab, undoubtedly played an important role in the development of the Silk Road. Scythians accompanied the Assyrian Esarhaddon on his invasion of Egypt, and their distinctive triangular arrowheads have been found as far south as Aswan. These nomadic peoples were dependent upon neighbouring settled populations for a number of important technologies, and in addition to raiding vulnerable settlements for these commodities, they also encouraged long-distance merchants as a source of income through the enforced payment of tariffs. Sogdians played a major role in facilitating trade between China and Central Asia along the Silk Roads as late as the 10th century, their language serving as a lingua franca for Asian trade as far back as the 4th century. === Initiation in China (130 BCE) === The Silk Road was initiated and spread by China's Han dynasty through exploration and conquests in Central Asia. With the Mediterranean linked to the Fergana Valley, the next step was to open a route across the Tarim Basin and the Hexi Corridor to China Proper. This extension came around 130 BCE, with the embassies of the Han dynasty to Central Asia following the reports of the ambassador Zhang Qian (who was originally sent to obtain an alliance with the Yuezhi against the Xiongnu). Zhang Qian visited directly the kingdom of Dayuan in Ferghana, the territories of the Yuezhi in Transoxiana, the Bactrian country of Daxia with its remnants of Greco-Bactrian rule, and Kangju. He also made reports on neighbouring countries that he did not visit, such as Anxi (Parthia), Tiaozhi (Mesopotamia), Shendu (Indian subcontinent) and the Wusun. Zhang Qian's report suggested the economic reason for Chinese expansion and wall-building westward, and trail-blazed the Silk Road, making it one of the most famous trade routes in history and in the world. After winning the War of the Heavenly Horses and the Han–Xiongnu War, Chinese armies established themselves in Central Asia, initiating the Silk Route as a major avenue of international trade. Some say that the Chinese Emperor Wu became interested in developing commercial relationships with the sophisticated urban civilizations of Ferghana, Bactria, and the Parthian Empire: "The Son of Heaven on hearing all this reasoned thus: Ferghana (Dayuan "Great Ionians") and the possessions of Bactria (Ta-Hsia) and Parthian Empire (Anxi) are large countries, full of rare things, with a population living in fixed abodes and given to occupations somewhat identical with those of the Chinese people, but with weak armies, and placing great value on the rich produce of China" (Hou Hanshu, Later Han History). Others say that Emperor Wu was mainly interested in fighting the Xiongnu and that major trade began only after the Chinese pacified the Hexi Corridor. The Chinese were also strongly attracted by the tall and powerful horses (named "heavenly horses") in the possession of the Dayuan (literally the "Great Ionians," the Greek kingdoms of Central Asia), which were of capital importance in fighting the nomadic Xiongnu. They defeated the Dayuan in the Han-Dayuan war. The Chinese subsequently sent numerous embassies, around ten every year, to these countries and as far as Seleucid Syria. Thus more embassies were dispatched to Anxi [Parthia], Yancai [who later joined the Alans ], Lijian [Syria under the Greek Seleucids], Tiaozhi (Mesopotamia), and Tianzhu [northwestern India] ... As a rule, rather more than ten such missions went forward in the course of a year, and at the least five or six. (Hou Hanshu, Later Han History). These connections marked the beginning of the Silk Road trade network that extended to the Roman Empire. The Chinese campaigned in Central Asia on several occasions, and direct encounters between Han troops and Roman legionaries (probably captured or recruited as mercenaries by the Xiong Nu) are recorded, particularly in the 36 BCE battle of Sogdiana (Joseph Needham, Sidney Shapiro). It has been suggested that the Chinese crossbow was transmitted to the Roman world on such occasions, although the Greek gastraphetes provides an alternative origin. R. Ernest Dupuy and Trevor N. Dupuy suggest that in 36 BCE, [A] Han expedition into Central Asia, west of Jaxartes River, apparently encountered and defeated a contingent of Roman legionaries. The Romans may have been part of Antony's army invading Parthia. Sogdiana (modern Bukhara), east of the Oxus River, on the Polytimetus River, was apparently the most easterly penetration ever made by Roman forces in Asia. The margin of Chinese victory appears to have been their crossbows, whose bolts and darts seem easily to have penetrated Roman shields and armour. The Han dynasty army regularly policed the trade route against nomadic bandit forces generally identified as Xiongnu. Han general Ban Chao led an army of 70,000 mounted infantry and light cavalry troops in the 1st century CE to secure the trade routes, reaching far west to the Tarim Basin. Ban Chao expanded his conquests across the Pamirs to the shores of the Caspian Sea and the borders of Parthia. It was from here that the Han general dispatched envoy Gan Ying to Daqin (Rome). The Silk Road essentially came into being from the 1st century BCE, following these efforts by China to consolidate a road to the Western world and India, both through direct settlements in the area of the Tarim Basin and diplomatic relations with the countries of the Dayuan, Parthians and Bactrians further west. The Silk Roads were a "complex network of trade routes" that gave people the chance to exchange goods and culture. A maritime Silk Route opened up between Chinese-controlled Giao Chỉ (centred in modern Vietnam, near Hanoi), probably by the 1st century. It extended, via ports on the coasts of India and Sri Lanka, all the way to Roman-controlled ports in Roman Egypt and the Nabataean territories on the northeastern coast of the Red Sea. The earliest Roman glassware bowl found in China was unearthed from a Western Han tomb in Guangzhou, dated to the early 1st century BCE, indicating that Roman commercial items were being imported through the South China Sea. According to Chinese dynastic histories, it is from this region that the Roman embassies arrived in China, beginning in 166 CE during the reigns of Marcus Aurelius and Emperor Huan of Han. Other Roman glasswares have been found in Eastern-Han-era tombs (25–220 CE) further inland in Luoyang, Nanyang, and Nanjing. === Roman Empire (30 BCE – 3rd century CE) === Soon after the Roman conquest of Egypt in 30 BCE, regular communications and trade between China, Southeast Asia, India, the Middle East, Africa, and Europe blossomed on an unprecedented scale. The Roman Empire inherited eastern trade routes that were part of the Silk Road from the earlier Hellenistic powers and the Arabs. With control of these trade routes, citizens of the Roman Empire received new luxuries and greater prosperity for the Empire as a whole. The Roman-style glassware discovered in the archeological sites of Gyeongju, the capital of the Silla kingdom (Korea) showed that Roman artifacts were traded as far as the Korean peninsula. The Greco-Roman trade with India started by Eudoxus of Cyzicus in 130 BCE continued to increase, and according to Strabo (II.5.12), by the time of Augustus, up to 120 ships were setting sail every year from Myos Hormos in Roman Egypt to India. The Roman Empire connected with the Central Asian Silk Road through their ports in Barygaza (known today as Bharuch) and Barbaricum (known today as the city of Karachi, Sindh, Pakistan) and continued along the western coast of India. An ancient "travel guide" to this Indian Ocean trade route was the Greek Periplus of the Erythraean Sea written in 60 CE. The travelling party of Maës Titianus penetrated farthest east along the Silk Road from the Mediterranean world, probably with the aim of regularising contacts and reducing the role of middlemen, during one of the lulls in Rome's intermittent wars with Parthia, which repeatedly obstructed movement along the Silk Road. Intercontinental trade and communication became regular, organised, and protected by the "Great Powers." Intense trade with the Roman Empire soon followed, confirmed by the Roman craze for Chinese silk (supplied through the Parthians), even though the Romans thought silk was obtained from trees. This belief was affirmed by Seneca the Younger in his Phaedra and by Virgil in his Georgics. Notably, Pliny the Elder knew better. Speaking of the bombyx or silk moth, he wrote in his Natural Histories "They weave webs, like spiders, that become a luxurious clothing material for women, called silk." The Romans traded spices, glassware, perfumes, and silk. Roman artisans began to replace yarn with valuable plain silk cloths from China and the Silla Kingdom in Gyeongju, Korea. Chinese wealth grew as they delivered silk and other luxury goods to the Roman Empire, whose wealthy women admired their beauty. The Roman Senate issued, in vain, several edicts to prohibit the wearing of silk, on economic and moral grounds: the import of Chinese silk caused a huge outflow of gold, and silk clothes were considered decadent and immoral. I can see clothes of silk, if materials that do not hide the body, nor even one's decency, can be called clothes. ... Wretched flocks of maids labour so that the adulteress may be visible through her thin dress, so that her husband has no more acquaintance than any outsider or foreigner with his wife's body. The Western Roman Empire, and its demand for sophisticated Asian products, collapsed in the fifth century. The unification of Central Asia and Northern India within the Kushan Empire between the first and third centuries reinforced the role of the powerful merchants from Bactria and Taxila. They fostered multi-cultural interaction as indicated by their 2nd century treasure hoards filled with products from the Greco-Roman world, China, and India, such as in the archeological site of Begram. === Byzantine Empire (6th–14th centuries) === Byzantine Greek historian Procopius stated that two Nestorian Christian monks eventually uncovered the way silk was made. From this revelation, monks were sent by the Byzantine Emperor Justinian (ruled 527–565) as spies on the Silk Road from Constantinople to China and back to steal the silkworm eggs, resulting in silk production in the Mediterranean, particularly in Thrace in northern Greece, and giving the Byzantine Empire a monopoly on silk production in medieval Europe. In 568, the Byzantine ruler Justin II was greeted by a Sogdian embassy representing Istämi, ruler of the First Turkic Khaganate, who formed an alliance with the Byzantines against Khosrow I of the Sasanian Empire that allowed the Byzantines to bypass the Sasanian merchants and trade directly with the Sogdians for purchasing Chinese silk. Although the Byzantines had already procured silkworm eggs from China by this point, the quality of Chinese silk was still far greater than anything produced in the West, a fact that is perhaps emphasized by the discovery of coins minted by Justin II found in a Chinese tomb of Shanxi province dated to the Sui dynasty (581–618). Both the Old Book of Tang and New Book of Tang, covering the history of the Chinese Tang dynasty (618–907), record that a new state called Fu-lin (拂菻; i.e. Byzantine Empire) was virtually identical to the previous Daqin (大秦; i.e. Roman Empire). Several Fu-lin embassies were recorded for the Tang period, starting in 643 with an alleged embassy by Constans II (transliterated as Bo duo li, 波多力, from his nickname "Kōnstantinos Pogonatos") to the court of Emperor Taizong of Tang. The History of Song describes the final embassy and its arrival in 1081, apparently sent by Michael VII Doukas (transliterated as Mie li yi ling kai sa, 滅力伊靈改撒, from his name and title Michael VII Parapinakēs Caesar) to the court of Emperor Shenzong of the Song dynasty (960–1279). However, the History of Yuan claims that a Byzantine man became a leading astronomer and physician in Khanbaliq, at the court of Kublai Khan, Mongol founder of the Yuan dynasty (1271–1368) and was even granted the noble title 'Prince of Fu lin' (Chinese: 拂菻王; Fú lǐn wáng). The Uyghur Nestorian Christian diplomat Rabban Bar Sauma, who set out from his Chinese home in Khanbaliq (Beijing) and acted as a representative for Arghun (a grandnephew of Kublai Khan), traveled throughout Europe and attempted to secure military alliances with Edward I of England, Philip IV of France, Pope Nicholas IV, as well as the Byzantine ruler Andronikos II Palaiologos. Andronikos II had two half-sisters who were married to great-grandsons of Genghis Khan, which made him an in-law with the Yuan-dynasty Mongol ruler in Beijing, Kublai Khan. The History of Ming preserves an account where the Hongwu Emperor, after founding the Ming dynasty (1368–1644), had a supposed Byzantine merchant named Nieh-ku-lun (捏古倫) deliver his proclamation about the establishment of a new dynasty to the Byzantine court of John V Palaiologos in September 1371. Friedrich Hirth (1885), Emil Bretschneider (1888), and more recently Edward Luttwak (2009) presumed that this was none other than Nicolaus de Bentra, a Roman Catholic bishop of Khanbilaq chosen by Pope John XXII to replace the previous archbishop John of Montecorvino. === Tang dynasty (7th century) === Although the Silk Road was initially formulated during the reign of Emperor Wu of Han (141–87 BCE), it was reopened by the Tang Empire in 639 when Hou Junji conquered the Western Regions, and remained open for almost four decades. It was closed after the Tibetans captured it in 678, but in 699, during Empress Wu's period, the Silk Road reopened when the Tang reconquered the Four Garrisons of Anxi originally installed in 640, once again connecting China directly to the West for land-based trade. The Tang captured the vital route through the Gilgit Valley from Tibet in 722, lost it to the Tibetans in 737, and regained it under the command of the Goguryeo-Korean General Gao Xianzhi. While the Turks were settled in the Ordos region (former territory of the Xiongnu), the Tang government took on the military policy of dominating the central steppe. The Tang dynasty (along with Turkic allies) conquered and subdued Central Asia during the 640s and 650s. During Emperor Taizong's reign alone, large campaigns were launched against not only the Göktürks, but also separate campaigns against the Tuyuhun, the oasis states, and the Xueyantuo. Under Emperor Taizong, Tang general Li Jing conquered the Eastern Turkic Khaganate. Under Emperor Gaozong, Tang general Su Dingfang conquered the Western Turkic Khaganate, an important ally of the Byzantine empire. After these conquests, the Tang dynasty fully controlled the Xiyu, which was the strategic location astride the Silk Road. This led the Tang dynasty to reopen the Silk Road, with this portion named the Tang-Tubo Road ("Tang-Tibet Road") in many historical texts. The Tang dynasty established a second Pax Sinica, and the Silk Road reached its golden age, whereby Persian and Sogdian merchants benefited from the commerce between East and West. At the same time, the Chinese empire welcomed foreign cultures, making it very cosmopolitan in its urban centres. In addition to the land route, the Tang dynasty also developed the maritime Silk Route. Chinese envoys had been sailing through the Indian Ocean to India since perhaps the 2nd century BCE, yet, it was during the Tang dynasty that a strong Chinese maritime presence could be found in the Persian Gulf and Red Sea into Persia, Mesopotamia (sailing up the Euphrates River in modern-day Iraq), Arabia, Egypt, Aksum (Ethiopia), and Somalia in the Horn of Africa. === Sogdian–Türkic tribes (4th–8th centuries) === The Silk Road represents an early phenomenon of political and cultural integration due to inter-regional trade. In its heyday, it sustained an international culture that strung together groups as diverse as the Magyars, Armenians, and Chinese. The Silk Road reached its peak in the west during the time of the Byzantine Empire; in the Nile-Oxus section, from the Sassanid Empire period to the Il Khanate period; and in the sinitic zone from the Three Kingdoms period to the Yuan dynasty period. Trade between East and West also developed across the Indian Ocean, between Alexandria in Egypt and Guangzhou in China. Persian Sassanid coins emerged as a means of currency, just as valuable as silk yarn and textiles. Under its strong integrating dynamics on the one hand and the impacts of change it transmitted on the other, tribal societies previously living in isolation along the Silk Road, and pastoralists who were of barbarian cultural development, were drawn to the riches and opportunities of the civilisations connected by the routes, taking on the trades of marauders or mercenaries. "Many barbarian tribes became skilled warriors able to conquer rich cities and fertile lands and to forge strong military empires." The Sogdians dominated the east–west trade after the 4th century up to the 8th century. They were the main caravan merchants of Central Asia. A.V. Dybo noted that "according to historians, the main driving force of the Great Silk Road were not just Sogdians, but the carriers of a mixed Sogdian-Türkic culture that often came from mixed families." The Silk Road gave rise to the clusters of military states of nomadic origins in North China, ushered the Nestorian, Manichaean, Buddhist, and later Islamic religions into Central Asia and China. === Islamic era (8th–13th centuries) === By the Umayyad era, Damascus had overtaken Ctesiphon as a major trade center until the Abbasid dynasty built the city of Baghdad, which became the most important city along the silk road. At the end of its glory, the routes brought about the largest continental empire ever, the Mongol Empire, with its political centres strung along the Silk Road (Beijing) in North China, Karakorum in central Mongolia, Sarmakhand in Transoxiana, Tabriz in Northern Iran, realising the political unification of zones previously loosely and intermittently connected by material and cultural goods. The Islamic world expanded into Central Asia during the 8th century, under the Umayyad Caliphate, while its successor the Abbasid Caliphate put a halt to Chinese westward expansion at the Battle of Talas in 751 (near the Talas River in modern-day Kyrgyzstan). However, following the disastrous An Lushan Rebellion (755–763) and the conquest of the Western Regions by the Tibetan Empire, the Tang Empire was unable to reassert its control over Central Asia. Contemporary Tang authors noted how the dynasty had gone into decline after this point. In 848 the Tang Chinese, led by the commander Zhang Yichao, were only able to reclaim the Hexi Corridor and Dunhuang in Gansu from the Tibetans. The Persian Samanid Empire (819–999) centered in Bukhara (Uzbekistan) continued the trade legacy of the Sogdians. The disruptions of trade were curtailed in that part of the world by the end of the 10th century and conquests of Central Asia by the Turkic Islamic Kara-Khanid Khanate, yet Nestorian Christianity, Zoroastrianism, Manichaeism, and Buddhism in Central Asia virtually disappeared. During the early 13th century Khwarezmia was invaded by the Mongol Empire. The Mongol ruler Genghis Khan had the once vibrant cities of Bukhara and Samarkand burned to the ground after besieging them. However, in 1370 Samarkand saw a revival as the capital of the new Timurid Empire. The Turko-Mongol ruler Timur forcefully moved artisans and intellectuals from across Asia to Samarkand, making it one of the most important trade centers and cultural entrepôts of the Islamic world. === Mongol Empire (13th–14th centuries) === The Mongol expansion throughout the Asian continent from around 1207 to 1360 helped bring political stability and re-established the Silk Road (via Karakorum and Khanbaliq). It also brought an end to the dominance of the Islamic Caliphate over world trade. Because the Mongols came to control the trade routes, trade circulated throughout the region, though they never abandoned their nomadic lifestyle. The Mongol rulers wanted to establish their capital on the Central Asian steppe, so to accomplish this goal, after every conquest they enlisted local people (traders, scholars, artisans) to help them construct and manage their empire. The Mongols developed overland and maritime routes throughout the Eurasian continent, Black Sea and the Mediterranean in the west, and the Indian Ocean in the south. In the second half of the thirteenth century Mongol-sponsored business partnerships flourished in the Indian Ocean connecting Mongol Middle East and Mongol China The Mongol diplomat Rabban Bar Sauma visited the courts of Europe in 1287–88 and provided a detailed written report to the Mongols. Around the same time, the Venetian explorer Marco Polo became one of the first Europeans to travel the Silk Road to China. His tales, documented in The Travels of Marco Polo, opened Western eyes to some of the customs of the Far East. He was not the first to bring back stories, but he was one of the most widely read. He had been preceded by numerous Christian missionaries to the East, such as William of Rubruck, Benedykt Polak, Giovanni da Pian del Carpine, and Andrew of Longjumeau. Later envoys included Odoric of Pordenone, Giovanni de' Marignolli, John of Montecorvino, Niccolò de' Conti, and Ibn Battuta, a Moroccan Muslim traveller who passed through the present-day Middle East and across the Silk Road from Tabriz between 1325 and 1354. In the 13th century, efforts were made at forming a Franco-Mongol alliance, with an exchange of ambassadors and (failed) attempts at military collaboration in the Holy Land during the later Crusades. Eventually, the Mongols in the Ilkhanate, after they had destroyed the Abbasid and Ayyubid dynasties, converted to Islam and signed the 1323 Treaty of Aleppo with the surviving Muslim power, the Egyptian Mamluks. Some studies indicate that the Black Death, which devastated Europe starting in the late 1340s, may have reached Europe from Central Asia (or China) along the trade routes of the Mongol Empire. One theory holds that Genoese traders coming from the entrepôt of Trebizond in northern Turkey carried the disease to Western Europe; like many other outbreaks of plague, there is strong evidence that it originated in marmots in Central Asia and was carried westwards to the Black Sea by Silk Road traders. === Decline (15th century – present) === The fragmentation of the Mongol Empire loosened the political, cultural, and economic unity of the Silk Road. Turkmeni marching lords seized land around the western part of the Silk Road from the decaying Byzantine Empire. After the fall of the Mongol Empire, the great political powers along the Silk Road became economically and culturally separated. Accompanying the crystallisation of regional states was the decline of nomad power, partly due to the devastation of the Black Death and partly due to the encroachment of sedentary civilisations equipped with gunpowder. Significant is Armenians' role in making Europe–Asia trade possible by being located in the crossing roads between these two. Armenia had a monopoly on almost all trade roads in this area and a colossal network. From 1700 to 1765, the total export of Persian silk was entirely conducted by Armenians. They were also exporting raisins, coffee beans, figs, Turkish yarn, camel hair, various precious stones, rice, etc., from Turkey and Iran. The silk trade continued to flourish until it was disrupted by the collapse of the Safavid Empire in the 1720s. == Expansion of religions == Richard Foltz, Xinru Liu, and others have described how trading activities along the Silk Road over many centuries facilitated the transmission not just of goods but also ideas and culture, notably in the area of religions. Zoroastrianism, Judaism, Buddhism, Christianity, Manichaeism, and Islam all spread across Eurasia through trade networks that were tied to specific religious communities and their institutions. Notably, established Buddhist monasteries along the Silk Road offered a haven, as well as a new religion for foreigners. The spread of religions and cultural traditions along the Silk Roads, according to Jerry H. Bentley, also led to syncretism. One example was the encounter with the Chinese and Xiongnu nomads. These unlikely events of cross-cultural contact allowed both cultures to adapt to each other as an alternative. The Xiongnu adopted Chinese agricultural techniques, dress style, and lifestyle, while the Chinese adopted Xiongnu military techniques, some dress style, music, and dance. Perhaps most surprising of the cultural exchanges between China and the Xiongnu, Chinese soldiers sometimes defected and converted to the Xiongnu way of life, and stayed in the steppes for fear of punishment. Nomadic mobility played a key role in facilitating inter-regional contacts and cultural exchanges along the ancient Silk Roads. === Transmission of Christianity === The transmission of Christianity was primarily known as Nestorianism on the Silk Road. In 781, an inscribed stele shows Nestorian Christian missionaries arriving on the Silk Road. Christianity had spread both east and west, simultaneously bringing Syriac language and evolving the forms of worship. === Transmission of Buddhism === The transmission of Buddhism to China via the Silk Road began in the 1st century CE, according to a semi-legendary account of an ambassador sent to the West by the Chinese Emperor Ming (58–75). During this period Buddhism began to spread throughout Southeast, East, and Central Asia. Mahayana, Theravada, and Vajrayana are the three primary forms of Buddhism that spread across Asia via the Silk Road. The Buddhist movement was the first large-scale missionary movement in the history of world religions. Chinese missionaries were able to assimilate Buddhism, to an extent, to native Chinese Daoists, which brought the two beliefs together. Buddha's community of followers, the Sangha, consisted of male and female monks and laity. These people moved through India and beyond to spread the ideas of Buddha. As the number of members within the Sangha increased, it became costly so that only the larger cities were able to afford having the Buddha and his disciples visit. It is believed that under the control of the Kushans, Buddhism was spread to China and other parts of Asia from the middle of the first century to the middle of the third century. Extensive contacts started in the 2nd century, probably as a consequence of the expansion of the Kushan empire into the Chinese territory of the Tarim Basin, due to the missionary efforts of a great number of Buddhist monks to Chinese lands. The first missionaries and translators of Buddhists scriptures into Chinese were either Parthian, Kushan, Sogdian, or Kuchean. One result of the spread of Buddhism along the Silk Road was displacement and conflict. The Greek Seleucids were exiled to Iran and Central Asia because of a new Iranian dynasty called the Parthians at the beginning of the 2nd century BCE, and as a result, the Parthians became the new middlemen for trade in a period when the Romans were major customers for silk. Parthian scholars were involved in one of the first-ever Buddhist text translations into the Chinese language. Its main trade centre on the Silk Road, the city of Merv, in due course and with the coming of age of Buddhism in China, became a major Buddhist centre by the middle of the 2nd century. Knowledge among people on the silk roads also increased when Emperor Ashoka of the Maurya dynasty (268–239 BCE) converted to Buddhism and raised the religion to official status in his northern Indian empire. From the 4th century CE onward, Chinese pilgrims also started to travel on the Silk Road to India to get improved access to the original Buddhist scriptures, with Fa-hsien's pilgrimage to India (395–414), and later Xuanzang (629–644) and Hyecho, who traveled from Korea to India. The travels of the priest Xuanzang were fictionalized in the 16th century in a fantasy adventure novel called Journey to the West, which told of trials with demons and the aid given by various disciples on the journey. There were many different schools of Buddhism travelling on the Silk Road. The Dharmaguptakas and the Sarvastivadins were two of the major Nikaya schools. These were both eventually displaced by the Mahayana, also known as "Great Vehicle." This movement of Buddhism first gained influence in the Khotan region. The Mahayana, which was more of a "pan-Buddhist movement" than a school of Buddhism, appears to have begun in northwestern India or Central Asia. It formed during the 1st century BCE and was small at first, and the origins of this "Greater Vehicle" are not fully clear. Some Mahayana scripts were found in northern Pakistan, but the main texts are still believed to have been composed in Central Asia along the Silk Road. These different schools and movements of Buddhism were a result of the diverse and complex influences and beliefs on the Silk Road. With the rise of Mahayana Buddhism, the initial direction of Buddhist development changed. This form of Buddhism highlighted, as stated by Xinru Liu, "the elusiveness of physical reality, including material wealth." It also stressed getting rid of material desire to a certain point; this was often difficult for followers to understand. During the 5th and 6th centuries CE, merchants played a large role in the spread of religion, in particular Buddhism. Merchants found the moral and ethical teachings of Buddhism an appealing alternative to previous religions. As a result, merchants supported Buddhist monasteries along the Silk Road, and in return, the Buddhists gave the merchants somewhere to stay as they traveled from city to city. As a result, merchants spread Buddhism to foreign encounters as they traveled. Merchants also helped to establish diaspora within the communities they encountered, and over time their cultures became based on Buddhism. As a result, these communities became centers of literacy and culture with well-organized marketplaces, lodging, and storage. The voluntary conversion of Chinese ruling elites helped the spread of Buddhism in East Asia and led Buddhism to become widespread in Chinese society. The Silk Road transmission of Buddhism essentially ended around the 7th century with the rise of Islam in Central Asia. === Judaism on the Silk Road === Adherents to the Jewish faith first began to travel eastward from Mesopotamia following the Persian conquest of Babylon in 559 by the armies of Cyrus the Great. Judean slaves freed after the Persian conquest of Babylon dispersed throughout the Persian Empire. Some Judeans could have traveled as far east as Bactria and Sogdia, though there is no clear evidence for this early settlement of Judeans. After settlement, it is likely that most Judeans took up trades in commerce. Trading along the silk trade networks by Judean merchants increased as the trade networks expanded. By the classical age, when trade goods traveled from as far east as China to as far west as Rome, Judean merchants in Central Asia would have been in an advantageous position to participate in trade along the Silk Road. A group of Judean merchants originating from Gaul known as the Radanites were one group of Judean merchants that had thriving trade networks from China to Rome. This trade was facilitated by a positive relationship the Radanites were able to foster with the Khazar Turks. The Khazar Turks served as a good spot in between China and Rome, and the Khazar Turks saw a relationship with the Radanites as a good commercial opportunity. According to Richard Foltz "there is more evidence for Iranian influence on the formation of Jewish [religious] ideas than the reverse." Concepts of a paradise (heaven) for the good and a place of suffering (hell) for the wicked, and a form or world-ending apocalypse came from Iranian religious ideas, and this is supported by a lack of such ideas from pre-exile Judean sources. The origin of the devil is also said to come from the Iranian Angra Mainyu, an evil figure in Persian mythology. == Expansion of the arts == Many artistic influences were transmitted via the Silk Road, particularly through Central Asia, where Hellenistic, Iranian, Indian and Chinese influences could intermix. Greco-Buddhist art represents one of the most vivid examples of this interaction. Silk was also a representation of art, serving as a religious symbol. Most importantly, silk was used as currency for trade along the silk road. These artistic influences can be seen in the development of Buddhism where, for instance, Buddha was first depicted as human in the Kushan period. Many scholars have attributed this to Greek influence. The mixture of Greek and Indian elements can be found in later Buddhist art in China and throughout countries on the Silk Road. The production of art consisted of many different items that were traded along the Silk Roads from the East to the West. One common product, the lapis lazuli, was a blue stone with golden specks, which was used as paint after it was ground into powder. == Commemoration == On 22 June 2014, the United Nations Educational, Scientific and Cultural Organization (UNESCO) named the Silk Road a World Heritage Site at the 2014 Conference on World Heritage. The United Nations World Tourism Organization has been working since 1993 to develop sustainable international tourism along the route with the stated goal of fostering peace and understanding. To commemorate the Silk Road becoming a UNESCO World Heritage Site, the China National Silk Museum announced a "Silk Road Week" to take place 19–25 June 2020. Bishkek and Almaty each have a major east–west street named after the Silk Road (Kyrgyz: Жибек жолу, Jibek Jolu in Bishkek, and Kazakh: Жібек жолы, Jibek Joly in Almaty). == Gallery == Silk Road and artifacts == See also == == References == === Notes === === Citations === === Sources === == Further reading == == External links == Silk Road Atlas (University of Washington) "The Silk Road," a historical overview by Oliver Wild The Silk Road Journal, a freely available scholarly journal run by Daniel Waugh "The New Silk Road" – a lecture by Paul Lacourbe at TEDx Danubia 2013 Escobar, Pepe (February 2015). "Year of the Sheep, Century of the Dragon? New Silk Roads and the Chinese Vision of a Brave New (Trade) World," an essay at Tom Dispatch

The Silk Road (Chinese: 丝绸之路) was a network of Eurasian trade routes active from the second century BCE until the mid-15th century. Spanning over 6,400 kilometers (4,000 miles), it played a central role in facilitating economic, cultural, political, and religious interactions between the East and West. The name "Silk Road," first coined in the late 19th century, has fallen into disuse among some modern historians in favor of Silk Routes, on the grounds that it more accurately describes the intricate web of land and sea routes connecting Central, East, South, Southeast, and West Asia as well as East Africa and Southern Europe. The Silk Road derives its name from the highly lucrative trade of silk textiles that were primarily produced in China. The network began with the Han dynasty's expansion into Central Asia around 114 BCE through the missions and explorations of the Chinese imperial envoy Zhang Qian, which brought the region under unified control. The Chinese took great interest in the security of their trade products, and extended the Great Wall of China to ensure the protection of the trade route. By the early first century CE, Chinese silk was widely sought-after in Rome, Egypt, and Greece. Other lucrative commodities from the East included tea, dyes, perfumes, and porcelain; among Western exports were horses, camels, honey, wine, and gold. Aside from generating substantial wealth for emerging mercantile classes, the proliferation of goods such as paper and gunpowder greatly altered the trajectory of various realms, if not world history. During its more than 1,500 years of existence, the Silk Road endured the rise and fall of numerous empires and major events such as the Black Death and the Mongol conquests. As a highly decentralized network, security was sparse. Travelers faced constant threats of banditry and nomadic raiders, and long expanses of inhospitable terrain. Few individuals crossed the entirety of the Silk Road, instead relying on a succession of middlemen based at various stopping points along the way. In addition to goods, the network facilitated an unprecedented exchange of ideas, religions (especially Buddhism), philosophies, and scientific discoveries, many of which were syncretised or reshaped by the societies that encountered them. Likewise, a wide variety of people used the routes. Diseases such as plague also spread along the Silk Road, possibly contributing to the Black Death. Despite repeatedly surviving many geopolitical changes and disruptions, the Ottoman Empire and other gunpowder empires expanded efforts to gain greater control of it from 1453 onwards. This prompted European efforts to seek alternative routes to trading with the gunpowder empires, as well as other nations and communities, while also gaining leverage over them in turn after the Ottomans increased their usage of land-based trade, thereby ushering in the Age of Discovery, European colonialism, and a more intensified process of globalization, which had arguably begun with the Silk Road. In the 21st century, the name "New Silk Road" is used to describe several large infrastructure projects along many of the historic trade routes; among the best known include the Eurasian Land Bridge and the Chinese Belt and Road Initiative (BRI). In June 2014, UNESCO designated the Chang'an-Tianshan corridor of the Silk Road as a World Heritage Site, while the Indian portion remains on the tentative site list.

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vacuum

Vakuum (wiktionary)

Latin vacuus IPA(key): /ˈvaːkuʊm/ Vakuum n (strong, genitive Vakuums, plural Vakua or Vakuen) vacuum “Vakuum” in Duden online “Vakuum” in Digitales Wörterbuch der deutschen Sprache

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vacuum

vakuum (wiktionary)

IPA(key): [ˈvakuum] vakuum n (related adjective vakuový) vacuum (empty space) Synonym: vzduchoprázdno n From Latin vacuum, neuter of vacuus (“empty”), from vacō (“I am empty”). IPA(key): /vaːkuɔm/, [ˈvæːˀkʰuɔm], IPA(key): /vakuɔm/, [ˈvɑkʰuɔm] or IPA(key): /vakɔm/, [ˈvɑkʰɔm] vakuum n (singular definite vakuummet, plural indefinite vakuummer) vacuum (region of space that contains no matter) vakuum on the Danish Wikipedia.Wikipedia da From Latin vacuum, neuter of vacuus. vakuum n (definite singular vakuumet, indefinite plural vakuum or vakuumer, definite plural vakuuma or vakuumene) a vacuum (area of space that contains no matter) maktvakuum “vakuum” in The Bokmål Dictionary. From Latin vacuum, neuter of vacuus. vakuum n (definite singular vakuumet, indefinite plural vakuum, definite plural vakuuma) a vacuum (as above) maktvakuum “vakuum” in The Nynorsk Dictionary. vakum vakuum m (Cyrillic spelling вакуум) vacuum vakuum n vacuum; a region of space that contains no matter (figuratively) vacuum; an isolated space without contact with the surrounding world vakuum in Svensk ordbok (SO) vakuum in Svenska Akademiens ordlista (SAOL) vakuum in Svenska Akademiens ordbok (SAOB)

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vacuum

vacuum (wiktionary)

vacuüm (rare) From Latin vacuum (“an empty space, void”), noun use of neuter of vacuus (“empty”), related to vacare (“be empty”). IPA(key): /ˈvæ.kjuːm/, /ˈvæ.kjuː.əm/ vacuum (plural vacuums or (rare, formal) vacua) A region of space that contains no matter. Synonyms: vacancy, void Antonym: plenum The condition of rarefaction, or reduction of pressure below that of the atmosphere, in a vessel, such as the condenser of a steam engine, which is nearly exhausted of air or steam, etc. (colloquial, only pluralized as "vacuums") Ellipsis of vacuum cleaner. Synonym: (British) hoover (physics) A spacetime having tensors of zero magnitude. An emptiness in life created by a loss of a person who was close, or of an occupation. An exercise in which one draws their abdomen towards the spine. The Latin in vacuo is sometimes used instead of in a vacuum (in free space). vacuum (third-person singular simple present vacuums, present participle vacuuming, simple past and past participle vacuumed) (transitive) To clean (something) with a vacuum cleaner. Synonym: (British) hoover (intransitive) To use a vacuum cleaner. Synonyms: (British) to do the hoovering, (British) to hoover (transitive, databases) To optimise a database or database table by physically removing deleted tuples. IPA(key): /va.kɥɔm/ vacuum m (plural vacuums) vacuum (space containing no matter) Synonym: vide Turkish: vakum “vacuum”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012. vacuum accusative neuter singular of vacuus Borrowed from Latin vacuum. vacuum n (plural vacuumuri) vacuum vácuum (recommended) vacuum m (plural vacuums) vacuum

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vacuum

Vacuum (wikipedia)

A vacuum (pl.: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective vacuus (neuter vacuum) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term in vacuo is used to describe an object that is surrounded by a vacuum. The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3. Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average in intergalactic space. Vacuum has been a frequent topic of philosophical debate since ancient Greek times, but was not studied empirically until the 17th century. Clemens Timpler (1605) philosophized about the experimental possibility of producing a vacuum in small tubes. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A Torricellian vacuum is created by filling with mercury a tall glass container closed at one end, and then inverting it in a bowl to contain the mercury (see below). Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technologies has since become available. The development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general. == Etymology == The word vacuum comes from Latin 'an empty space, void', noun use of neuter of vacuus, meaning "empty", related to vacare, meaning "to be empty". Vacuum is one of the few words in the English language that contains two consecutive instances of the vowel u. == Historical understanding == Historically, there has been much dispute over whether such a thing as a vacuum can exist. Ancient Greek philosophers debated the existence of a vacuum, or void, in the context of atomism, which posited void and atom as the fundamental explanatory elements of physics. Following Plato, even the abstract concept of a featureless void faced considerable skepticism: it could not be apprehended by the senses, it could not, itself, provide additional explanatory power beyond the physical volume with which it was commensurate and, by definition, it was quite literally nothing at all, which cannot rightly be said to exist. Aristotle believed that no void could occur naturally, because the denser surrounding material continuum would immediately fill any incipient rarity that might give rise to a void. In his Physics, book IV, Aristotle offered numerous arguments against the void: for example, that motion through a medium which offered no impediment could continue ad infinitum, there being no reason that something would come to rest anywhere in particular. Lucretius argued for the existence of vacuum in the first century BC and Hero of Alexandria tried unsuccessfully to create an artificial vacuum in the first century AD. In the medieval Muslim world, the physicist and Islamic scholar Al-Farabi wrote a treatise rejecting the existence of the vacuum in the 10th century. He concluded that air's volume can expand to fill available space, and therefore the concept of a perfect vacuum was incoherent. According to Ahmad Dallal, Abū Rayhān al-Bīrūnī states that "there is no observable evidence that rules out the possibility of vacuum". The suction pump was described by Arab engineer Al-Jazari in the 13th century, and later appeared in Europe from the 15th century. European scholars such as Roger Bacon, Blasius of Parma and Walter Burley in the 13th and 14th century focused considerable attention on issues concerning the concept of a vacuum. Eventually following Stoic physics in this instance, scholars from the 14th century onward increasingly departed from the Aristotelian perspective in favor of a supernatural void beyond the confines of the cosmos itself, a conclusion widely acknowledged by the 17th century, which helped to segregate natural and theological concerns. Almost two thousand years after Plato, René Descartes also proposed a geometrically based alternative theory of atomism, without the problematic nothing–everything dichotomy of void and atom. Although Descartes agreed with the contemporary position, that a vacuum does not occur in nature, the success of his namesake coordinate system and more implicitly, the spatial–corporeal component of his metaphysics would come to define the philosophically modern notion of empty space as a quantified extension of volume. By the ancient definition however, directional information and magnitude were conceptually distinct. Medieval thought experiments into the idea of a vacuum considered whether a vacuum was present, if only for an instant, between two flat plates when they were rapidly separated. There was much discussion of whether the air moved in quickly enough as the plates were separated, or, as Walter Burley postulated, whether a 'celestial agent' prevented the vacuum arising. The commonly held view that nature abhorred a vacuum was called horror vacui. There was even speculation that even God could not create a vacuum if he wanted and the 1277 Paris condemnations of Bishop Étienne Tempier, which required there to be no restrictions on the powers of God, led to the conclusion that God could create a vacuum if he so wished. Jean Buridan reported in the 14th century that teams of ten horses could not pull open bellows when the port was sealed. The 17th century saw the first attempts to quantify measurements of partial vacuum. Evangelista Torricelli's mercury barometer of 1643 and Blaise Pascal's experiments both demonstrated a partial vacuum. In 1654, Otto von Guericke invented the first vacuum pump and conducted his famous Magdeburg hemispheres experiment, showing that, owing to atmospheric pressure outside the hemispheres, teams of horses could not separate two hemispheres from which the air had been partially evacuated. Robert Boyle improved Guericke's design and with the help of Robert Hooke further developed vacuum pump technology. Thereafter, research into the partial vacuum lapsed until 1850 when August Toepler invented the Toepler pump and in 1855 when Heinrich Geissler invented the mercury displacement pump, achieving a partial vacuum of about 10 Pa (0.1 Torr). A number of electrical properties become observable at this vacuum level, which renewed interest in further research. While outer space provides the most rarefied example of a naturally occurring partial vacuum, the heavens were originally thought to be seamlessly filled by a rigid indestructible material called aether. Borrowing somewhat from the pneuma of Stoic physics, aether came to be regarded as the rarefied air from which it took its name, (see Aether (mythology)). Early theories of light posited a ubiquitous terrestrial and celestial medium through which light propagated. Additionally, the concept informed Isaac Newton's explanations of both refraction and of radiant heat. 19th century experiments into this luminiferous aether attempted to detect a minute drag on the Earth's orbit. While the Earth does, in fact, move through a relatively dense medium in comparison to that of interstellar space, the drag is so minuscule that it could not be detected. In 1912, astronomer Henry Pickering commented: "While the interstellar absorbing medium may be simply the ether, [it] is characteristic of a gas, and free gaseous molecules are certainly there". Later, in 1930, Paul Dirac proposed a model of the vacuum as an infinite sea of particles possessing negative energy, called the Dirac sea. This theory helped refine the predictions of his earlier formulated Dirac equation, and successfully predicted the existence of the positron, confirmed two years later. Werner Heisenberg's uncertainty principle, formulated in 1927, predicted a fundamental limit within which instantaneous position and momentum, or energy and time can be measured. This has far reaching consequences on the "emptiness" of space between particles. == Classical field theories == The strictest criterion to define a vacuum is a region of space and time where all the components of the stress–energy tensor are zero. This means that this region is devoid of energy and momentum, and by consequence, it must be empty of particles and other physical fields (such as electromagnetism) that contain energy and momentum. === Gravity === In general relativity, a vanishing stress–energy tensor implies, through Einstein field equations, the vanishing of all the components of the Ricci tensor. Vacuum does not mean that the curvature of space-time is necessarily flat: the gravitational field can still produce curvature in a vacuum in the form of tidal forces and gravitational waves (technically, these phenomena are the components of the Weyl tensor). The black hole (with zero electric charge) is an elegant example of a region completely "filled" with vacuum, but still showing a strong curvature. === Electromagnetism === In classical electromagnetism, the vacuum of free space, or sometimes just free space or perfect vacuum, is a standard reference medium for electromagnetic effects. Some authors refer to this reference medium as classical vacuum, a terminology intended to separate this concept from QED vacuum or QCD vacuum, where vacuum fluctuations can produce transient virtual particle densities and a relative permittivity and relative permeability that are not identically unity. In the theory of classical electromagnetism, free space has the following properties: Electromagnetic radiation travels, when unobstructed, at the speed of light, the defined value 299,792,458 m/s in SI units. The superposition principle is always exactly true. For example, the electric potential generated by two charges is the simple addition of the potentials generated by each charge in isolation. The value of the electric field at any point around these two charges is found by calculating the vector sum of the two electric fields from each of the charges acting alone. The permittivity and permeability are exactly the electric constant ε0 and magnetic constant μ0, respectively (in SI units), or exactly 1 (in Gaussian units). The characteristic impedance (η) equals the impedance of free space Z0 ≈ 376.73 Ω. The vacuum of classical electromagnetism can be viewed as an idealized electromagnetic medium with the constitutive relations in SI units: D ( r , t ) = ε 0 E ( r , t ) {\displaystyle {\boldsymbol {D}}({\boldsymbol {r}},\ t)=\varepsilon _{0}{\boldsymbol {E}}({\boldsymbol {r}},\ t)\,} H ( r , t ) = 1 μ 0 B ( r , t ) {\displaystyle {\boldsymbol {H}}({\boldsymbol {r}},\ t)={\frac {1}{\mu _{0}}}{\boldsymbol {B}}({\boldsymbol {r}},\ t)\,} relating the electric displacement field D to the electric field E and the magnetic field or H-field H to the magnetic induction or B-field B. Here r is a spatial location and t is time. == Quantum mechanics == In quantum mechanics and quantum field theory, the vacuum is defined as the state (that is, the solution to the equations of the theory) with the lowest possible energy (the ground state of the Hilbert space). In quantum electrodynamics this vacuum is referred to as 'QED vacuum' to distinguish it from the vacuum of quantum chromodynamics, denoted as QCD vacuum. QED vacuum is a state with no matter particles (hence the name), and no photons. As described above, this state is impossible to achieve experimentally. (Even if every matter particle could somehow be removed from a volume, it would be impossible to eliminate all the blackbody photons.) Nonetheless, it provides a good model for realizable vacuum, and agrees with a number of experimental observations as described next. QED vacuum has interesting and complex properties. In QED vacuum, the electric and magnetic fields have zero average values, but their variances are not zero. As a result, QED vacuum contains vacuum fluctuations (virtual particles that hop into and out of existence), and a finite energy called vacuum energy. Vacuum fluctuations are an essential and ubiquitous part of quantum field theory. Some experimentally verified effects of vacuum fluctuations include spontaneous emission and the Lamb shift. Coulomb's law and the electric potential in vacuum near an electric charge are modified. Theoretically, in QCD multiple vacuum states can coexist. The starting and ending of cosmological inflation is thought to have arisen from transitions between different vacuum states. For theories obtained by quantization of a classical theory, each stationary point of the energy in the configuration space gives rise to a single vacuum. String theory is believed to have a huge number of vacua – the so-called string theory landscape. == Outer space == Outer space has very low density and pressure, and is the closest physical approximation of a perfect vacuum. But no vacuum is truly perfect, not even in interstellar space, where there are still a few hydrogen atoms per cubic meter. Stars, planets, and moons keep their atmospheres by gravitational attraction, and as such, atmospheres have no clearly delineated boundary: the density of atmospheric gas simply decreases with distance from the object. The Earth's atmospheric pressure drops to about 32 millipascals (4.6×10−6 psi) at 100 kilometres (62 mi) of altitude, the Kármán line, which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar winds, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre. But although it meets the definition of outer space, the atmospheric density within the first few hundred kilometers above the Kármán line is still sufficient to produce significant drag on satellites. Most artificial satellites operate in this region called low Earth orbit and must fire their engines every couple of weeks or a few times a year (depending on solar activity). The drag here is low enough that it could theoretically be overcome by radiation pressure on solar sails, a proposed propulsion system for interplanetary travel. All of the observable universe is filled with large numbers of photons, the so-called cosmic background radiation, and quite likely a correspondingly large number of neutrinos. The current temperature of this radiation is about 3 K (−270.15 °C; −454.27 °F). == Measurement == The quality of a vacuum is indicated by the amount of matter remaining in the system, so that a high quality vacuum is one with very little matter left in it. Vacuum is primarily measured by its absolute pressure, but a complete characterization requires further parameters, such as temperature and chemical composition. One of the most important parameters is the mean free path (MFP) of residual gases, which indicates the average distance that molecules will travel between collisions with each other. As the gas density decreases, the MFP increases, and when the MFP is longer than the chamber, pump, spacecraft, or other objects present, the continuum assumptions of fluid mechanics do not apply. This vacuum state is called high vacuum, and the study of fluid flows in this regime is called particle gas dynamics. The MFP of air at atmospheric pressure is very short, 70 nm, but at 100 mPa (≈10−3 Torr) the MFP of room temperature air is roughly 100 mm, which is on the order of everyday objects such as vacuum tubes. The Crookes radiometer turns when the MFP is larger than the size of the vanes. Vacuum quality is subdivided into ranges according to the technology required to achieve it or measure it. These ranges were defined in ISO 3529-1:2019 as shown in the following table (100 Pa corresponds to 0.75 Torr; Torr is a non-SI unit): Atmospheric pressure is variable but 101.325 and 100 kilopascals (1013.25 and 1000.00 mbar) are common standard or reference pressures. Deep space is generally much more empty than any artificial vacuum. It may or may not meet the definition of high vacuum above, depending on what region of space and astronomical bodies are being considered. For example, the MFP of interplanetary space is smaller than the size of the Solar System, but larger than small planets and moons. As a result, solar winds exhibit continuum flow on the scale of the Solar System, but must be considered a bombardment of particles with respect to the Earth and Moon. Perfect vacuum is an ideal state of no particles at all. It cannot be achieved in a laboratory, although there may be small volumes which, for a brief moment, happen to have no particles of matter in them. Even if all particles of matter were removed, there would still be photons and gravitons, as well as dark energy, virtual particles, and other aspects of the quantum vacuum. === Relative versus absolute measurement === Vacuum is measured in units of pressure, typically as a subtraction relative to ambient atmospheric pressure on Earth. But the amount of relative measurable vacuum varies with local conditions. On the surface of Venus, where ground-level atmospheric pressure is much higher than on Earth, much higher relative vacuum readings would be possible. On the surface of the Moon with almost no atmosphere, it would be extremely difficult to create a measurable vacuum relative to the local environment. Similarly, much higher than normal relative vacuum readings are possible deep in the Earth's ocean. A submarine maintaining an internal pressure of 1 atmosphere submerged to a depth of 10 atmospheres (98 metres; a 9.8-metre column of seawater has the equivalent weight of 1 atm) is effectively a vacuum chamber keeping out the crushing exterior water pressures, though the 1 atm inside the submarine would not normally be considered a vacuum. Therefore, to properly understand the following discussions of vacuum measurement, it is important that the reader assumes the relative measurements are being done on Earth at sea level, at exactly 1 atmosphere of ambient atmospheric pressure. === Measurements relative to 1 atm === The SI unit of pressure is the pascal (symbol Pa), but vacuum is often measured in torrs, named for an Italian physicist Torricelli (1608–1647). A torr is equal to the displacement of a millimeter of mercury (mmHg) in a manometer with 1 torr equaling 133.3223684 pascals above absolute zero pressure. Vacuum is often also measured on the barometric scale or as a percentage of atmospheric pressure in bars or atmospheres. Low vacuum is often measured in millimeters of mercury (mmHg) or pascals (Pa) below standard atmospheric pressure. "Below atmospheric" means that the absolute pressure is equal to the current atmospheric pressure. In other words, most low vacuum gauges that read, for example 50.79 Torr. Many inexpensive low vacuum gauges have a margin of error and may report a vacuum of 0 Torr but in practice this generally requires a two-stage rotary vane or other medium type of vacuum pump to go much beyond (lower than) 1 torr. === Measuring instruments === Many devices are used to measure the pressure in a vacuum, depending on what range of vacuum is needed. Hydrostatic gauges (such as the mercury column manometer) consist of a vertical column of liquid in a tube whose ends are exposed to different pressures. The column will rise or fall until its weight is in equilibrium with the pressure differential between the two ends of the tube. The simplest design is a closed-end U-shaped tube, one side of which is connected to the region of interest. Any fluid can be used, but mercury is preferred for its high density and low vapour pressure. Simple hydrostatic gauges can measure pressures ranging from 1 torr (100 Pa) to above atmospheric. An important variation is the McLeod gauge which isolates a known volume of vacuum and compresses it to multiply the height variation of the liquid column. The McLeod gauge can measure vacuums as high as 10−6 torr (0.1 mPa), which is the lowest direct measurement of pressure that is possible with current technology. Other vacuum gauges can measure lower pressures, but only indirectly by measurement of other pressure-controlled properties. These indirect measurements must be calibrated via a direct measurement, most commonly a McLeod gauge. The kenotometer is a particular type of hydrostatic gauge, typically used in power plants using steam turbines. The kenotometer measures the vacuum in the steam space of the condenser, that is, the exhaust of the last stage of the turbine. Mechanical or elastic gauges depend on a Bourdon tube, diaphragm, or capsule, usually made of metal, which will change shape in response to the pressure of the region in question. A variation on this idea is the capacitance manometer, in which the diaphragm makes up a part of a capacitor. A change in pressure leads to the flexure of the diaphragm, which results in a change in capacitance. These gauges are effective from 103 torr to 10−4 torr, and beyond. Thermal conductivity gauges rely on the fact that the ability of a gas to conduct heat decreases with pressure. In this type of gauge, a wire filament is heated by running current through it. A thermocouple or Resistance Temperature Detector (RTD) can then be used to measure the temperature of the filament. This temperature is dependent on the rate at which the filament loses heat to the surrounding gas, and therefore on the thermal conductivity. A common variant is the Pirani gauge which uses a single platinum filament as both the heated element and RTD. These gauges are accurate from 10 torr to 10−3 torr, but they are sensitive to the chemical composition of the gases being measured. Ionization gauges are used in ultrahigh vacuum. They come in two types: hot cathode and cold cathode. In the hot cathode version an electrically heated filament produces an electron beam. The electrons travel through the gauge and ionize gas molecules around them. The resulting ions are collected at a negative electrode. The current depends on the number of ions, which depends on the pressure in the gauge. Hot cathode gauges are accurate from 10−3 torr to 10−10 torr. The principle behind cold cathode version is the same, except that electrons are produced in a discharge created by a high voltage electrical discharge. Cold cathode gauges are accurate from 10−2 torr to 10−9 torr. Ionization gauge calibration is very sensitive to construction geometry, chemical composition of gases being measured, corrosion and surface deposits. Their calibration can be invalidated by activation at atmospheric pressure or low vacuum. The composition of gases at high vacuums will usually be unpredictable, so a mass spectrometer must be used in conjunction with the ionization gauge for accurate measurement. == Uses == Vacuum is useful in a variety of processes and devices. Its first widespread use was in the incandescent light bulb to protect the filament from chemical degradation. The chemical inertness produced by a vacuum is also useful for electron beam welding, cold welding, vacuum packing and vacuum frying. Ultra-high vacuum is used in the study of atomically clean substrates, as only a very good vacuum preserves atomic-scale clean surfaces for a reasonably long time (on the order of minutes to days). High to ultra-high vacuum removes the obstruction of air, allowing particle beams to deposit or remove materials without contamination. This is the principle behind chemical vapor deposition, physical vapor deposition, and dry etching which are essential to the fabrication of semiconductors and optical coatings, and to surface science. The reduction of convection provides the thermal insulation of thermos bottles. Deep vacuum lowers the boiling point of liquids and promotes low temperature outgassing which is used in freeze drying, adhesive preparation, distillation, metallurgy, and process purging. The electrical properties of vacuum make electron microscopes and vacuum tubes possible, including cathode ray tubes. Vacuum interrupters are used in electrical switchgear. Vacuum arc processes are industrially important for production of certain grades of steel or high purity materials. The elimination of air friction is useful for flywheel energy storage and ultracentrifuges. === Vacuum-driven machines === Vacuums are commonly used to produce suction, which has an even wider variety of applications. The Newcomen steam engine used vacuum instead of pressure to drive a piston. In the 19th century, vacuum was used for traction on Isambard Kingdom Brunel's experimental atmospheric railway. Vacuum brakes were once widely used on trains in the UK but, except on heritage railways, they have been replaced by air brakes. Manifold vacuum can be used to drive accessories on automobiles. The best known application is the vacuum servo, used to provide power assistance for the brakes. Obsolete applications include vacuum-driven windscreen wipers and Autovac fuel pumps. Some aircraft instruments (Attitude Indicator (AI) and the Heading Indicator (HI)) are typically vacuum-powered, as protection against loss of all (electrically powered) instruments, since early aircraft often did not have electrical systems, and since there are two readily available sources of vacuum on a moving aircraft, the engine and an external venturi. Vacuum induction melting uses electromagnetic induction within a vacuum. Maintaining a vacuum in the condenser is an important aspect of the efficient operation of steam turbines. A steam jet ejector or liquid ring vacuum pump is used for this purpose. The typical vacuum maintained in the condenser steam space at the exhaust of the turbine (also called condenser backpressure) is in the range 5 to 15 kPa (absolute), depending on the type of condenser and the ambient conditions. === Outgassing === Evaporation and sublimation into a vacuum is called outgassing. All materials, solid or liquid, have a small vapour pressure, and their outgassing becomes important when the vacuum pressure falls below this vapour pressure. Outgassing has the same effect as a leak and will limit the achievable vacuum. Outgassing products may condense on nearby colder surfaces, which can be troublesome if they obscure optical instruments or react with other materials. This is of great concern to space missions, where an obscured telescope or solar cell can ruin an expensive mission. The most prevalent outgassing product in vacuum systems is water absorbed by chamber materials. It can be reduced by desiccating or baking the chamber, and removing absorbent materials. Outgassed water can condense in the oil of rotary vane pumps and reduce their net speed drastically if gas ballasting is not used. High vacuum systems must be clean and free of organic matter to minimize outgassing. Ultra-high vacuum systems are usually baked, preferably under vacuum, to temporarily raise the vapour pressure of all outgassing materials and boil them off. Once the bulk of the outgassing materials are boiled off and evacuated, the system may be cooled to lower vapour pressures and minimize residual outgassing during actual operation. Some systems are cooled well below room temperature by liquid nitrogen to shut down residual outgassing and simultaneously cryopump the system. === Pumping and ambient air pressure === Fluids cannot generally be pulled, so a vacuum cannot be created by suction. Suction can spread and dilute a vacuum by letting a higher pressure push fluids into it, but the vacuum has to be created first before suction can occur. The easiest way to create an artificial vacuum is to expand the volume of a container. For example, the diaphragm muscle expands the chest cavity, which causes the volume of the lungs to increase. This expansion reduces the pressure and creates a partial vacuum, which is soon filled by air pushed in by atmospheric pressure. To continue evacuating a chamber indefinitely without requiring infinite growth, a compartment of the vacuum can be repeatedly closed off, exhausted, and expanded again. This is the principle behind positive displacement pumps, like the manual water pump for example. Inside the pump, a mechanism expands a small sealed cavity to create a vacuum. Because of the pressure differential, some fluid from the chamber (or the well, in our example) is pushed into the pump's small cavity. The pump's cavity is then sealed from the chamber, opened to the atmosphere, and squeezed back to a minute size. The above explanation is merely a simple introduction to vacuum pumping, and is not representative of the entire range of pumps in use. Many variations of the positive displacement pump have been developed, and many other pump designs rely on fundamentally different principles. Momentum transfer pumps, which bear some similarities to dynamic pumps used at higher pressures, can achieve much higher quality vacuums than positive displacement pumps. Entrapment pumps can capture gases in a solid or absorbed state, often with no moving parts, no seals and no vibration. None of these pumps are universal; each type has important performance limitations. They all share a difficulty in pumping low molecular weight gases, especially hydrogen, helium, and neon. The lowest pressure that can be attained in a system is also dependent on many things other than the nature of the pumps. Multiple pumps may be connected in series, called stages, to achieve higher vacuums. The choice of seals, chamber geometry, materials, and pump-down procedures will all have an impact. Collectively, these are called vacuum technique. And sometimes, the final pressure is not the only relevant characteristic. Pumping systems differ in oil contamination, vibration, preferential pumping of certain gases, pump-down speeds, intermittent duty cycle, reliability, or tolerance to high leakage rates. In ultra high vacuum systems, some very "odd" leakage paths and outgassing sources must be considered. The water absorption of aluminium and palladium becomes an unacceptable source of outgassing, and even the adsorptivity of hard metals such as stainless steel or titanium must be considered. Some oils and greases will boil off in extreme vacuums. The permeability of the metallic chamber walls may have to be considered, and the grain direction of the metallic flanges should be parallel to the flange face. The lowest pressures currently achievable in laboratory are about 1×10−13 torrs (13 pPa). However, pressures as low as 5×10−17 torrs (6.7 fPa) have been indirectly measured in a 4 K (−269.15 °C; −452.47 °F) cryogenic vacuum system. This corresponds to ≈100 particles/cm3. == Effects on humans and animals == Humans and animals exposed to vacuum will lose consciousness after a few seconds and die of hypoxia within minutes, but the symptoms are not nearly as graphic as commonly depicted in media and popular culture. The reduction in pressure lowers the temperature at which blood and other body fluids boil, but the elastic pressure of blood vessels ensures that this boiling point remains above the internal body temperature of 37 °C. Although the blood will not boil, the formation of gas bubbles in bodily fluids at reduced pressures, known as ebullism, is still a concern. The gas may bloat the body to twice its normal size and slow circulation, but tissues are elastic and porous enough to prevent rupture. Swelling and ebullism can be restrained by containment in a flight suit. Shuttle astronauts wore a fitted elastic garment called the Crew Altitude Protection Suit (CAPS) which prevents ebullism at pressures as low as 2 kPa (15 Torr). Rapid boiling will cool the skin and create frost, particularly in the mouth, but this is not a significant hazard. Animal experiments show that rapid and complete recovery is normal for exposures shorter than 90 seconds, while longer full-body exposures are fatal and resuscitation has never been successful. A study by NASA on eight chimpanzees found all of them survived two and a half minute exposures to vacuum. There is only a limited amount of data available from human accidents, but it is consistent with animal data. Limbs may be exposed for much longer if breathing is not impaired. Robert Boyle was the first to show in 1660 that vacuum is lethal to small animals. An experiment indicates that plants are able to survive in a low pressure environment (1.5 kPa) for about 30 minutes. Cold or oxygen-rich atmospheres can sustain life at pressures much lower than atmospheric, as long as the density of oxygen is similar to that of standard sea-level atmosphere. The colder air temperatures found at altitudes of up to 3 km generally compensate for the lower pressures there. Above this altitude, oxygen enrichment is necessary to prevent altitude sickness in humans that did not undergo prior acclimatization, and spacesuits are necessary to prevent ebullism above 19 km. Most spacesuits use only 20 kPa (150 Torr) of pure oxygen. This pressure is high enough to prevent ebullism, but decompression sickness and gas embolisms can still occur if decompression rates are not managed. Rapid decompression can be much more dangerous than vacuum exposure itself. Even if the victim does not hold his or her breath, venting through the windpipe may be too slow to prevent the fatal rupture of the delicate alveoli of the lungs. Eardrums and sinuses may be ruptured by rapid decompression, soft tissues may bruise and seep blood, and the stress of shock will accelerate oxygen consumption leading to hypoxia. Injuries caused by rapid decompression are called barotrauma. A pressure drop of 13 kPa (100 Torr), which produces no symptoms if it is gradual, may be fatal if it occurs suddenly. Some extremophile microorganisms, such as tardigrades, can survive vacuum conditions for periods of days or weeks. == Examples == == See also == == References == Henning Genz (2001). Nothingness: The Science Of Empty Space. Da Capo Press. ISBN 978-0-7382-0610-3. Luciano Boi (2011). The Quantum Vacuum: A Scientific and Philosophical Concept, from Electrodynamics to String Theory and the Geometry of the Microscopic World. Johns Hopkins University Press. ISBN 978-1-4214-0247-5. == External links == Leybold – Fundamentals of Vacuum Technology (PDF) VIDEO on the nature of vacuum by Canadian astrophysicist Doctor P The Foundations of Vacuum Coating Technology American Vacuum Society Journal of Vacuum Science and Technology A Journal of Vacuum Science and Technology B FAQ on explosive decompression and vacuum exposure. Discussion of the effects on humans of exposure to hard vacuum. Roberts, Mark D. (2000). "Vacuum Energy". High Energy Physics – Theory: hep–th/0012062. arXiv:hep-th/0012062. Bibcode:2000hep.th...12062R. Vacuum, Production of Space "Much Ado About Nothing" by Professor John D. Barrow, Gresham College Free pdf copy of The Structured Vacuum – thinking about nothing by Johann Rafelski and Berndt Muller (1985) ISBN 3-87144-889-3.

A vacuum (pl.: vacuums or vacua) is space devoid of matter. The word is derived from the Latin adjective vacuus (neuter vacuum) meaning "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often discuss ideal test results that would occur in a perfect vacuum, which they sometimes simply call "vacuum" or free space, and use the term partial vacuum to refer to an actual imperfect vacuum as one might have in a laboratory or in space. In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is considerably lower than atmospheric pressure. The Latin term in vacuo is used to describe an object that is surrounded by a vacuum. The quality of a partial vacuum refers to how closely it approaches a perfect vacuum. Other things equal, lower gas pressure means higher-quality vacuum. For example, a typical vacuum cleaner produces enough suction to reduce air pressure by around 20%. But higher-quality vacuums are possible. Ultra-high vacuum chambers, common in chemistry, physics, and engineering, operate below one trillionth (10−12) of atmospheric pressure (100 nPa), and can reach around 100 particles/cm3. Outer space is an even higher-quality vacuum, with the equivalent of just a few hydrogen atoms per cubic meter on average in intergalactic space. Vacuum has been a frequent topic of philosophical debate since ancient Greek times, but was not studied empirically until the 17th century. Clemens Timpler (1605) philosophized about the experimental possibility of producing a vacuum in small tubes. Evangelista Torricelli produced the first laboratory vacuum in 1643, and other experimental techniques were developed as a result of his theories of atmospheric pressure. A Torricellian vacuum is created by filling with mercury a tall glass container closed at one end, and then inverting it in a bowl to contain the mercury (see below). Vacuum became a valuable industrial tool in the 20th century with the introduction of incandescent light bulbs and vacuum tubes, and a wide array of vacuum technologies has since become available. The development of human spaceflight has raised interest in the impact of vacuum on human health, and on life forms in general.

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Vacuum (band) (wikipedia)

Vacuum is a Swedish pop band consisting of Mattias Lindblom and Anders Wollbeck. They also work as song writers and producers under the same name. As songwriters and producers Wollbeck and Lindblom have worked with artists such as Tarja Turunen, Tina Arena, Garou, Monrose, TVXQ, Keisha Buchanan, f(x) and The Canadian Tenors. Wollbeck and Lindblom are signed to Universal Music Publishing world wide. Playing symphonic pop, the group scored successes in countries like Italy and Russia. == History == Vacuum was formed in 1996 by Anders Wollbeck, Alexander Bard and Mattias Lindblom. Their first single "I Breathe" was a big hit in large parts of Europe. At that time Marina Schiptjenko was part of the group. After the second album Bard left the group. Vacuum then released the single "Starting Where the Story Ended". Schiptjenko left the group shortly after. Wollbeck and Lindblom wrote and produced, in 2004, Vacuum's critically acclaimed album Your Whole Life Is Leading up to This, marking a new direction for the band. At that point Wollbeck and Lindblom had started writing and producing for other artists as well. Vacuum then released the singles "Six Billion Voices" in 2006 and "Walk on the Sun" in 2007. In 2008 Wollbeck and Lindblom started a collaboration with Austrian pianist Michael Zlanabitnig. It resulted in the release of "Know by Now" and "My Friend Misery". The latter being a duet with Marcella Detroit. In 2009 they released "The Ocean". Another single written in collaboration with Zlanabitnig. On June 4, 2011, Vacuum released the song "Black Angels". == Discography == === Albums === The Plutonium Cathedral (1997) Parallel Universe (4:10) I Breathe (4:35) Pride in My Religion (4:01) Science of the Sacred (4:52) Rise and Shine Olympia (4:00) Atlas Shrugged (4:38) Illuminati (4:14) Woman Named America (4:16) Prussia (4:38) The Shape of Things to Come (4:01) Sign on the Skyline (5:25) Tin Soldiers (4:29) Closer Than the Holy Ghost (5:02) Seance at the Chaebol (1998) Tonnes of Attraction Power Tears of a Nation Let the Mountain Come to Me Chant like a Mantra Satyricon Nuclear India Culture of Night Big Ideas Grand Vision Ulysses I Breathe (slightly shorter version) Science of the Sacred (slightly shorter version) Culture of Night (2000, three new songs + two songs with new sound, Russian release only) Culture of Night (2002, yet another two new songs) Your Whole Life Is Leading Up to This (2004) Intro Your whole life is leading up to this They do it (feat. K) Mind your Mind The Void In the Dirt Love Earth Cry (feat. Jessica Pilnäs) Something Evil I Love Sea of Silence A Shallow Heart Queen Fools like me Dead Temporary Solution Your Whole Life Is Leading Up to This (2007, five new bonustracks + video, German release only) === Singles === "I Breathe" (1996) "Science of the Sacred" (1997) "Pride in My Religion" (1997) "Tonnes of Attraction" (1998) "Let the Mountain Come to Me" (1998) "Icaros" (2000) "Starting (Where the Story Ended)" (2002) "Fools Like Me" (2004) "They Do It" (2004) "The Void" (2005) "Open My Eyes" (2005) "Six Billion Voices" (2006) "Walk On The Sun" (2007) "Know By Now" (2008) "My Friend Misery" (2008) "Where Angels Belong" (2009) "The Ocean" (2009) "Black Angels" (2011) "I Loved You" (2012) "Animal" (2013) "You Are Everywhere" (2020) == Members == Mattias Lindblom Anders Wollbeck == References == == External links == Official Vacuum page on Facebook Official Vacuum Website Mattias Lindblom on Instagram Vacuum on SoundCloud Illuminati Arts - Mattias Lindblom (Tumblr Blog) on Archived December 6, 2017, at the Wayback Machine

Vacuum is a Swedish pop band consisting of Mattias Lindblom and Anders Wollbeck. They also work as song writers and producers under the same name. As songwriters and producers Wollbeck and Lindblom have worked with artists such as Tarja Turunen, Tina Arena, Garou, Monrose, TVXQ, Keisha Buchanan, f(x) and The Canadian Tenors. Wollbeck and Lindblom are signed to Universal Music Publishing world wide. Playing symphonic pop, the group scored successes in countries like Italy and Russia.

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vacuum

Vacuum (disambiguation) (wikipedia)

Vacuum is the absence of matter. Vacuum may also refer to: Vacuum cleaner, a home appliance which uses suction to remove dirt Vacuum flask, an insulated storage vessel Vacuum (outer space), the very high, but imperfect, vacuum of the solar system and interstellar space Ultra-high vacuum Vacuum state, the quantum state with the lowest possible energy Vacuum (journal), academic journal on vacuum science and technology Vacuum Oil Company, an 1866 US petroleum company, now part of ExxonMobil Vacuum (band), a musical group from Sweden The Vacuum, a free monthly newspaper published in Belfast, Northern Ireland Vacuum, a 2006 play by Deborah McAndrew Vacuum, a 2004 album by The Watch VACUUM, a data set clean-up process

41

vacuum

Vacuum (journal) (wikipedia)

Vacuum is a quarterly peer-reviewed scientific journal published by the Elsevier. Founded in 1951, the journal covers the fundamental research and technical advances in vacuum engineering, materials science and surface science. Its editor-in-chief is Lars Hultman (Linköping University). According to the Journal Citation Reports, the journal has a 2023 impact factor of 3.8. == References == == External links == Official website

Vacuum is a quarterly peer-reviewed scientific journal published by the Elsevier. Founded in 1951, the journal covers the fundamental research and technical advances in vacuum engineering, materials science and surface science. Its editor-in-chief is Lars Hultman (Linköping University). According to the Journal Citation Reports, the journal has a 2023 impact factor of 3.8.

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tu

Tu (wiktionary)

Tu Abbreviation of Tuesday. Borrowed from Chinese. Tu (plural Tus) A surname from Chinese. Hanks, Patrick, editor (2003), “Tu”, in Dictionary of American Family Names, volume 3, New York City: Oxford University Press, →ISBN. Forebears UT, ut

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tu

tu (wiktionary)

tu Pronunciation spelling of to, representing African-American Vernacular English. IPA(key): /ˈtu/ [ˈtʊ] tú f thing ím E. M. Parker, R. J. Hayward (1985) “tu”, in An Afar-English-French dictionary (with Grammatical Notes in English), University of London, →ISBN Mohamed Hassan Kamil (2015) L’afar: description grammaticale d’une langue couchitique (Djibouti, Erythrée et Ethiopie)‎[2], Paris: Université Sorbonne Paris Cité (doctoral thesis) IPA(key): /tu/ tu (Kana spelling トゥ) two Unknown. tu may From Latin tū, from Proto-Italic *tū, from Proto-Indo-European *túh₂. tu you (singular) tini/tine ti io/iou, mini el/elu, nãs noi voi nãsh, elj Compare tru. tu in into tru, ãn From Latin tū. tu you (singular) From English two. IPA(key): /tu/ tu (Bengali script তু) two ni rongni do van Breugel, Seino. 2015. Atong-English dictionary, second edition. Available online: https://www.academia.edu/487044/Atong_English_Dictionary. Stated in Appendix 2. tu forest; thicket tu to spit (out) Borrowed from Indonesian tua. tu old Daigle (2015). Cited in: "Batuley" in Greenhill, S.J., Blust, R., & Gray, R.D. (2008). The Austronesian Basic Vocabulary Database: From Bioinformatics to Lexomics. Evolutionary Bioinformatics, 4:271–283. IPA(key): /tu/ tu give Big Nambas Grammar Pacific Linguistics - G.J. Fox From English two. tu two From English too. tu too tu to go From Proto-Brythonic *tʉβ, from Proto-Celtic *toibos, whence also Old Irish tóeb and Irish taobh. Cognate with Welsh tu, Cornish tu. tu m side From Old Catalan tu, from Latin tū. IPA(key): (Central, Balearic, Valencia) [ˈtu] Rhymes: -u tu you (singular); thou one (singular, impersonal) vostè, vós (plural or polite) vosaltres (plural) “tu” in Diccionari català-valencià-balear, Antoni Maria Alcover and Francesc de Borja Moll, 1962. From Proto-Athabaskan *tuˑ. tu water Eung-Do Cook (2013) A Tsilhqút'ín Grammar From Proto-Athabaskan [Term?]; cognate with Hän chuu, Ahtna tuu, Deg Xinag te, Navajo tó, Gwich'in chųų, etc. tu water Eung-Do Cook (2004) A grammar of Dëne Sųłiné (Chipewyan), page 350 tu one SIL Zapotec Basic Vocabulary, page 52 tu Hard mutation of du. Mixed mutation of du. IPA(key): [ˈtu] Inherited from Old Czech tu, from Proto-Slavic *tu. tu (informal or dialectal) here Synonyms: zde, tady See the etymology of the corresponding lemma form. tu feminine accusative singular of ten tu in Příruční slovník jazyka českého, 1935–1957 tu in Slovník spisovného jazyka českého, 1960–1971, 1989 tu in Internetová jazyková příručka From Proto-Sino-Tibetan *s-tawŋ. tu thousand Ross Perlin (2019) A Grammar of Trung‎[3], Santa Barbara: University of California tu (plural tuwo) gun tu to build to close to crush to grind to meet to untie tu f sg (Lagarteiru) Apocopic form of túa (“your”) Used in Lagarteiru before a feminine singular noun as part of a noun phrase. Valeš, Miroslav (2021) Diccionariu de A Fala: lagarteiru, mañegu, valverdeñu (web)‎[4], 2nd edition, Minde, Portugal: CIDLeS, published 2022, →ISBN Borrowed from English two. tu two IPA(key): /tu/ tu to stand to be (only in situations regarding posture or position) IPA(key): /ty/ (Quebec) IPA(key): [t͡sy], [t͡sʏ] (Louisiana) IPA(key): [ti], [t͡ʃy] Homophones: tue, tues, tuent, tus, tut, tût Rhymes: -y From Old French tu, from Latin tū, from Proto-Italic *tū, from Proto-Indo-European *túh₂. Cognates with the exact same usage are the Italian tu, as well as du in German or ты in Russian. tu (second person informal singular, plural vous, object te, emphatic toi, possessive determiner ton) you (singular); thou When more pronouns are included in the same sentence, it is considered somewhat impolite to say the pronoun moi first, etiquette says it must be the last one, and toi must be said after a third person: Rose, toi et moi irons là-bas., “Rose, you and I will go there.” "Tu" is used to address one person in an informal situation. Older people tend to exclusively use it with familiar people, and do not use it with unfamiliar adults unless invited to; but younger people use this pronoun much more, using it together in any informal situation, even if they don't know each other. Using "vous" in this context will be seen as old-fashioned and distant. "Tu" is not typically used in formal settings such as business meetings and never in court, regardless of the relationship between the speaker and the listener. Using "vous" when "tu" would be more appropriate will come across as rigid and awkward; however, using "tu" when "vous" would be more appropriate could come over as deliberate disrespect. For this reason, as a rule of thumb, it is advised to use "vous" if in doubt, as it is "all-encompassing". Children are always addressed using "tu" – vous would come over as comical. In elementary, middle, and high schools, teachers address students using "tu", but students address teachers using vous*. In higher education usage of vous becomes more common in both directions. In formal written communication to any adult, use vous. Not doing so may come over as unprofessional at best, deliberately disrespectful at worst. *However, depending on the region or type of school, other norms may be more used in place. For example, in Quebec (not the rest of Canada), it is more common for students to use "tu" with their teachers. As a final note: These come as natural to a person who grew up in a French-speaking country, but not necessarily for outsiders. If you are obviously a foreigner, people will normally be forgiving of such mistakes. Nominative: tu Emphatic: toi Oblique: te t’ (proclitic form, colloquial) vous (plural form and polite singular form) tu (feminine tue, masculine plural tus, feminine plural tues) past participle of taire From t-il. tu (Quebec, informal) question marker C’est-tu possible ? ― Is it possible? “tu”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012. ut From Latin tū, from Proto-Indo-European *túh₂. tu you From Proto-Celtic *tū, from Proto-Indo-European *túh₂. tū (plural suīs) you (singular); thou Nominative: tū Accusative: ti/te Dative: toi Václav Blažek (2008) “Gaulish Language”, in Sborník prací filozofické fakulty brněnské univerzity / Studia minora facultatis philosophicae universitatis brunensis‎[5], page 59 IPA(key): /tuː/ Rhymes: -uː tu singular imperative of tun IPA(key): /tuʔ/ Rhymes: -tu tu this (what is being indicated) tu this hari tu Borrowed from English thou, French tu, German du, Italian tu, Spanish tú, Russian ты (ty), all ultimately from Proto-Indo-European *túh₂ with +‎ -u. IPA(key): /tu/ tu (second person singular) (informal, familiar) you (singular), thou Synonym: (formal) vu From Latin and common Romance tu. IPA(key): /tu/ tu (second person singular) you (singular); thou tu (possessive) your From Latin tū, from Proto-Italic *tū, from Proto-Indo-European *túh₂. IPA(key): /ˈtu/* (most parts of Latium) IPA(key): /ˈtu/° Rhymes: -u Hyphenation: tù tu (second person singular) you (singular); thou Italian being a pro-drop language, subject pronouns are mostly omitted, both in the written and spoken language, as the inflected verb is conjugated by person. An example would be: Mangi una mela, which is much more common than Tu mangi una mela, where the subject can be inferred from the inflected form mangi ; similarly È carina instead of Lei è carina. The explicit usage of personal pronouns may sound redundant to a native speaker, except when it is used in order to emphasize the subject. (Tu mangi una mela could be interpreted as You are eating an apple and I am not).. The second-person pronoun in particular can sound confidential and, in some cases, even impolite. tu in Luciano Canepari, Dizionario di Pronuncia Italiana (DiPI) Derived from English to. IPA(key): /tu/ tu to tu at majstro.com tu The katakana syllable トゥ (tu) in Hepburn-like romanization. tu you (2nd-person personal pronoun) tu you (singular) “tu” in Finnish Romani-English Dictionary, ROMLEX – the Romani Lexicon Project, 2000. Inherited from Proto-Slavic *tu. IPA(key): /ˈtu/ Rhymes: -u Syllabification: tu tu (not comparable) here (at this place) Synonym: tuwò Coordinate term: tam Stefan Ramułt (1893) “tu”, in Słownik języka pomorskiego czyli kaszubskiego (in Kashubian), page 216 Eùgeniusz Gòłąbk (2011) “tu”, in Słownik Polsko-Kaszubski / Słowôrz Pòlskò-Kaszëbsczi‎[6] “tu”, in Internetowi Słowôrz Kaszëbsczégò Jãzëka [Internet Dictionary of the Kashubian Language], Fundacja Kaszuby, 2022 From Proto-Kuki-Chin [Term?], from Proto-Sino-Tibetan *tu. Cognates include Burmese တူ (tu) and Chinese 錘／锤 (chuí). IPA(key): /tu˩/ tu hammer K. E. Herr (2011) The phonological interpretation of minor syllables, applied to Lemi Chin‎[7], Payap University, page 48 IPA(key): /tu/ tu (Latin spelling) (informal) you (singular) vozotros (masculine plural) vozotras (feminine plural) vos (formal singular) tu (Latin spelling) your From Proto-Balto-Slavic *tū, Proto-Indo-European *túh₂. Cognates include Latvian tu and Lithuanian tu. IPA(key): [ˈtu] Hyphenation: tu tu thou, you (singular) (in reported speech) he, she (that is addressed) A. Andronov, L. Leikuma (2008) Latgalīšu-Latvīšu-Krīvu sarunu vuordineica, Lvava, →ISBN, page 10 Nicole Nau (2011) A short grammar of Latgalian, München: LINCOM GmbH, →ISBN, page 35 From Proto-Italic *tū, from Proto-Indo-European *túh₂ or *tū. (Classical Latin) IPA(key): /tuː/, [t̪uː] (modern Italianate Ecclesiastical) IPA(key): /tu/, [t̪uː] tū (second person singular, possessive adjective tuus) you (singular); thou When used in the plural genitive, vestrī is used when it is the object of an action, especially when used with a gerund or gerundive. When used in such a construction, the gerund or gerundive takes on the masculine genitive singular. Vestrum is used as a partitive genitive, used in constructions such as (one of you). Plautus sometimes has sg. gen. tis. Tēd is an early form of tē. For quotations using this term, see Citations:tu. "tu", in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press "tu", in Charlton T. Lewis (1891) An Elementary Latin Dictionary, New York: Harper & Brothers From Proto-Balto-Slavic *tū, Proto-Indo-European *túh₂. The Latvian tevis comes from *tevens, with an -en-increased form showing an additional s by analogy with other genitive plurals. The dative form was originally closer to Old Prussian tebbei; the current form tev has a v due to influence from other declension forms, and the ending was reduced. The accusative tevi comes from *teven, with n by analogy to the accusative form of other words. The locative tevī was formed by analogy with i-stem nouns. IPA(key): [tu] tu (personal, 2nd person singular) (informal in the singular) you; (dated) thou; second person pronoun, referring to the addressee vai tu nāksi man līdzi? ― are you coming with me? pieder tautai, tad tauta piederēs tev! ― belong to the people, and then the people will belong to you! būt uz tu ar kādu ― to be on intimate terms (lit. to be on thou) with someone (in the expression “ak tu...”) used to strengthen the meaning of a word or expression "ak tu to skaļo gaiļa rīkli!" māte priecājas ― "oh you loud rooster throat!" mother said happily ak tu mūžs! cūka izlauzusies no aizgalda! ― ah (you) life! the pig escaped from the pen! The dative form tevim is used only optionally, with prepositions. tavējs vietniekvārds Personal pronouns (personu vietniekvārdi):es - tu - viņš - viņa - mēs - jūs - viņi - viņas From Proto-Balto-Slavic *tuˀ (“you”), from Proto-Indo-European *tuH. The oblique stem tav- has been generalized from the Proto-Indo-European genitive *téwe. For a discussion of the case endings, see àš (“I”). IPA(key): /tʊ/ tù you (singular) IPA(key): /tu/ tu accusative feminine singular of ten From Proto-Athabaskan *tuˑ. tu water James Kari (1991) Lower Tanana Athabaskan Listening and Writing Exercises itu, تو, ايت Shortened form of itu, from Proto-Malayic *(i)tu(ʔ), from Proto-Malayo-Polynesian *(i-)tu, from Proto-Austronesian *(i-)Cu. IPA(key): /tu/ Rhymes: -tu, -u Rhymes: -u tu (colloquial) that (what is being indicated) tu (colloquial) that (that thing) tu Nonstandard spelling of tū. Nonstandard spelling of tú. Nonstandard spelling of tǔ. Nonstandard spelling of tù. Transcriptions of Mandarin into the Latin script often do not distinguish between the critical tonal differences employed in the Mandarin language, using words such as this one without indication of tone. Inherited from Old Polish tu. IPA(key): /ˈtu/ Rhymes: -u Syllabification: tu tu here From Proto-Otomi *dų, from Proto-Otomian [Term?], from Proto-Oto-Pamean *tõ, from Proto-Oto-Manguean *ti(n). IPA(key): /tù/ tu (intransitive) die IPA(key): /tǔ/ tu contain exist IPA(key): /tǔ/ tu owe tu Alternative form of þou (“thou”) tu you (the second-person singular pronoun) From Latin tū. IPA(key): /ˈtu/ tu you (second-person singular nominative pronoun) AIS: Sprach- und Sachatlas Italiens und der Südschweiz [Linguistic and Ethnographic Atlas of Italy and Southern Switzerland] – map 1653: “voglio che tu finisca” – on navigais-web.pd.istc.cnr.it From English too. tu too very From English two. tu two tu (Mooring) to 1867, Kleine Mittheilungen. Zur Sammlung der Sagen, Märchen und Lieder, der Sitten und Gebräuche der Herzogthümer Schleswig, Holstein und Lauenburg. Nachträge, herausgegeben von Dr. Handelmann in Jahrbücher für die Landeskunde der Herzogthümer Schleswig, Holstein und Lauenburg herausgegeben von der S. H. L. Gesellschaft für vaterländische Geschichte. Band IX., p. 126 (Von der Insel Amrum. Mitgetheilt von Chr. Johansen) From Proto-Iranian *tuHám, from Proto-Indo-Iranian *túH, from Proto-Indo-European *túh₂. IPA(key): [tʊ] tu (second person singular) you (singular); thou te hûn oto, otor, tur, to, tor tu (dialectal, Trøndelag, Eastern Norway) Nonstandard form of ut or (“out from, out of”). From Old Occitan tu, from Latin tū. IPA(key): /ty/ tu you (singular) Inherited from Proto-Slavic *tu. IPA(key): (13th CE) /ˈtu/ IPA(key): (15th CE) /ˈtu/ tu here (at this place) Synonyms: tuto, tuž, tuže Coordinate term: tam Czech: tu Jan Gebauer (1903–1916) “tu”, in Slovník staročeský (in Czech), Prague: Česká grafická společnost "unie", Česká akademie císaře Františka Josefa pro vědy, slovesnost a umění From Proto-Germanic *twō, neuter of *twai. IPA(key): /tuː/ tū neuter nominative/accusative of tweġen From Latin tū, from Proto-Indo-European *túh₂. IPA(key): /ˈtu/ tu thou, you (singular second person pronoun) Fala: tu Galician: tu, ti Portuguese: tu tu Alternative spelling of tú Inherited from Proto-Slavic *tu. First attested in the 14th century. IPA(key): (10th–15th CE) /tu/ IPA(key): (15th CE) /tu/ tu here (at this place) Synonym: tuta here, hither (to this place) then (at that time) here (in this situation) Masurian: tu Polish: tu B. Sieradzka-Baziur, editor (2011–2015), “tu”, in Słownik pojęciowy języka staropolskiego [Conceptual Dictionary of Old Polish] (in Polish), Kraków: IJP PAN, →ISBN tu Alternative form of þū From Sanskrit तुवम् (tuvam, “thou”). IPA(key): /tu/ tu (personal, Perso-Arabic spelling توۡ) you (2sg nom subject or direct object) Liljegren, Henrik, Haider, Naseem (2011) Palula Vocabulary (FLI Language and Culture Series; 7)‎[8], Islamabad, Pakistan: Forum for Language Initiatives, →ISBN Turner, Ralph Lilley (1969–1985) “tu”, in A Comparative Dictionary of the Indo-Aryan Languages, London: Oxford University Press Inherited from Old Polish tu. IPA(key): /tu/ (Middle Polish) IPA(key): /ˈtu/ Rhymes: -u Syllabification: tu tu here (at this place) Synonym: tutaj Coordinate term: tam here; hither (to this place) Synonym: tutaj Coordinate term: tam here; now (at this time) Synonym: tutaj tu (colloquial, telephony) used by the speaker to introduce themselves on the telephone; speaking Synonyms: tutaj, z tej strony Tu Janek! ― Janek speaking! used by the speaker to indicate they are thinking (colloquial) expressive particle, usually of anger (colloquial) particle of uncertainty of success on the speaker's part According to Słownik frekwencyjny polszczyzny współczesnej (1990), tu is one of the most used words in Polish, appearing 1-2 times in scientific texts, 42 times in news, 113 times in essays, 169 times in fiction, and 353 times in plays, each out of a corpus of 100,000 words, totaling 779 times, making it the 57th most common word in a corpus of 500,000 words. tu in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN tu in Polish dictionaries at PWN “TU”, in Elektroniczny Słownik Języka Polskiego XVII i XVIII Wieku [Electronic Dictionary of the Polish Language of the XVII and XVIII Century], 30.03.2020 “TU”, in Elektroniczny Słownik Języka Polskiego XVII i XVIII Wieku [Electronic Dictionary of the Polish Language of the XVII and XVIII Century], 06.09.2008 Samuel Bogumił Linde (1807–1814) “tu”, in Słownik języka polskiego Aleksander Zdanowicz (1861) “tu”, in Słownik języka polskiego, Wilno 1861 J. Karłowicz, A. Kryński, W. Niedźwiedzki, editors (1919), “tu”, in Słownik języka polskiego (in Polish), volume 7, Warsaw, page 162 Rhymes: -u Hyphenation: tu From Old Galician-Portuguese tu, from Latin tū (“you”), from Proto-Italic *tū, from Proto-Indo-European *túh₂ (“you”). tu (informal in Portugal, literary, archaic or regional in Brazil) you; thou (singular second person pronoun) Synonyms: (Brazil, formal) o senhor, (formal in Portugal, neutral in Brazil) você, (formal, archaic) vossa mercê, (formal, archaic) vosmecê, (formal, obsolete) vossemecê (Brazil, colloquial, proscribed) second-person singular prepositional pronoun Ela gosta de tu. ― She's into you. Tu has fallen out of use in some regions of Brazil, including most of the Southeast and the Centre-West, where "você" has taken its place. It is still very commonly used in various regions of the country though, such as most of Santa Catarina and Rio Grande do Sul, parts of Paraná, Rio de Janeiro city and most of the Northeast and North regions. It should be noted that in Rio de Janeiro the pronoun is frequently employed interchangeably with você. Despite the media's preference for "você", the usage of "tu" seems to have been gaining ground throughout the last few decades in Rio (see [9], a linguistic research on the topic in Portuguese), being most frequent among younger speakers. According to grammars, tu should always take second person singular verbs, as is the case in Portugal and some parts of Brazil. However, in most Brazilian dialects which employ tu, it now takes third person singular verbs, like você. tu (onomatopoeia) the sound produced by a telephone after one of the callers hangs up From Sanskrit त्वम् (tvam), from Proto-Indo-European *túh₂. tu you (singular) From Latin tū, from Proto-Italic *tū, from Proto-Indo-European *túh₂. IPA(key): /tu/ tu you (singular), thou Synonyms: (semi-polite form) dumneata, (polite form) dumneavoastră From Latin tū, from Proto-Italic *tū, from Proto-Indo-European *túh₂. IPA(key): /tu/ tu you (singular) Synonym: (formal, now rare) vosthè Rubattu, Antoninu (2006) Dizionario universale della lingua di Sardegna, 2nd edition, Sassari: Edes From Sanskrit त्वम् (tvam). tu you; second-person singular and plural personal pronoun Nina Knobloch (2020) A grammar sketch of Sauji: An Indo-Aryan language of Afghanistan‎[10], Stockholm University IPA(key): /ˈt̪ʰu/ tu (emphatic tusa) Form of thu (“thou, you”) used after verb forms ending in -n, -s or -dh. From Proto-Slavic *tu. tȗ (Cyrillic spelling ту̑) here (in this place) Tu nikad nismo bili. ― We have never been here. (proximal) here, over here (in the indicated place nearby) Eno ih tu! ― Here they are! over here (to, towards this place) Dođi tu! ― Come over here! (Croatia) tuj (here, over here): óvdje (there, over there): tȁmo, ondje tuni From Latin tū. IPA(key): /tu/ tu (second person singular) you (informal); thou Inherited from Old Polish tu. IPA(key): /ˈtu/ Rhymes: -u Syllabification: tu tu here (at this place) Synonyms: sam, tukej, samtukej Coordinate terms: (regional) hań, (Cieszyń) hanej, (Cieszyń) han, tam tu in silling.org tu you (singular) “tu” in Sinte Romani-English Dictionary, ROMLEX – the Romani Lexicon Project, 2000. IPA(key): /tú/ tȕ here, in this place tȗkaj “tu”, in Slovarji Inštituta za slovenski jezik Frana Ramovša ZRC SAZU, portal Fran “tu”, in Termania, Amebis See also the general references (Jean Marie River) ti From Proto-Athabaskan *tuˑ. Cognates include Navajo tó and Chipewyan tuu. IPA(key): [tʰù(ʔ)] Hyphenation: tu tu (stem -tu-) water Keren Rice (1989) A Grammar of Slave, Berlin, West Germany: Mouton de Gruyter, →ISBN, page 90 From Latin tuus, from Proto-Indo-European *towos. IPA(key): /tu/ [t̪u] Rhymes: -u Syllabification: tu Homophone: tú tu sg (second person singular possessive of singular, of plural tus) (before the noun) Apocopic form of tuyo, your Synonym: (parts of Central and South America) su The forms tu and tus are only used before and within the noun phrase of the modified noun. In other positions, a form of tuyo is used instead: Son tus libros. ― They are your books. Son los libros tuyos. ― They are your books. (literally, “They are the books of yours.”) Besides being a pronoun, because tu occurs in a noun phrase and expresses reference, it also grammatically classifies as a determiner (specifically a possessive/genitive determiner). “tu”, in Diccionario de la lengua española, Vigésima tercera edición, Real Academia Española, 2014 From English two. tu two From English too. tu too, also, as well Synonym: owktu From Proto-Balto-Slavic *tūˀ, from Proto-Indo-European *túh₂. Compare Lithuanian tù, Latvian tu, Old Prussian tu, tou. tu (second-person singular) you, thou tu only From Old Norse tvau, neuter nominative/accusative of tveir. Rhymes: -ʉː tu (archaic, in the neuter) two Synonym: två tu was the old neuter of två. Thus, one would say "ett hus" (one house), "tu hus" (two houses). The equivalent for the number three was try or tri, which is likewise archaic. tu in Svensk ordbok. ut From Proto-Athabaskan *tuˑ. tu water Jeff Leer, Proto-Athabaskan verb stem variation (1979), page 83 From Proto-Malayo-Polynesian *tuqu. tu right (not left) tu right hand From Proto-Malayo-Polynesian *təlu. tu three From Proto-Austronesian *tuduq. tu a drop tu (used in the form magtu) to drip From Proto-Tai *tuːᴬ. Cognate with Thai ตู (dtuu), Northern Thai ᨲᩪ, Lao ຕູ (tū), Lü ᦎᦴ (ṫuu), Tai Dam ꪔꪴ, Shan တူ (tǔu), Tai Nüa ᥖᥧ (tu), Ahom 𑜄𑜥 (tū), Zhuang dou. (Thạch An – Tràng Định) IPA(key): [tu˧˧] (Trùng Khánh) IPA(key): [tu˦˥] tu (閗, 須) door Lục Văn Pảo, Hoàng Tuấn Nam (2003) Hoàng Triều Ân, editor, Từ điển chữ Nôm Tày [A Dictionary of (chữ) Nôm Tày]‎[11] (in Vietnamese), Hanoi: Nhà xuất bản Khoa học Xã hội Hoàng Văn Ma, Lục Văn Pảo, Hoàng Chí (2006) Từ điển Tày-Nùng-Việt [Tay-Nung-Vietnamese dictionary] (in Vietnamese), Hanoi: Nhà xuất bản Từ điển Bách khoa Hà Nội Lương Bèn (2011) Từ điển Tày-Việt [Tay-Vietnamese dictionary]‎[12][13] (in Vietnamese), Thái Nguyên: Nhà Xuất bản Đại học Thái Nguyên tu one SIL Zapotec Basic Vocabulary, page 53 tu water Michael Foster, Timbe grammar sketch - cohesion in Timbe texts (1981, online 2009), page 10 From Proto-Tocharian [Term?], from Proto-Indo-European *túh₂. Cognate with Tocharian B tuwe. tu you, thou From English two. tu two Used when counting; see also tupela. From English too. tu too; also; as well From Proto-Athabaskan *tuˑ. Cognate with Navajo tó, Dogrib ti, Gwich'in chųų IPA(key): /tʰu/ tú water Gūnáhà. Tsuut'ina Gunaha Institute. https://gunaha.altlab.app/ From Proto-Athabaskan *tuˑ. tu water Raymond L. Collins, Betty Petruska, Dinak'i (our Words): Upper Kuskokwim Athabaskan Junior Dictionary (1979) (Hà Nội) IPA(key): [tu˧˧] (Huế) IPA(key): [tʊw˧˧] (Saigon) IPA(key): [tʊw˧˧] Sino-Vietnamese word from 修. tu (intransitive) to isolate oneself from other people to follow rules in a philosophy or religion tu (transitive) to drink directly from a bottle by holding bottle mouth in one's mouth Borrowed from English too. IPA(key): /tu/ tu (degree) too, excessively. From Proto-Brythonic *tʉβ, from Proto-Celtic *toibos, whence also Old Irish tóeb and Irish taobh. Cognate with Breton tu, Cornish tu. (North Wales) IPA(key): /tɨː/ (South Wales) IPA(key): /tiː/ Homophone: tŷ; (South Wales) ti tu m (uncountable) side tu beside, next to R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “tu”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies tu you (singular) “tu” in Welsh Romani-English Dictionary, ROMLEX – the Romani Lexicon Project, 2000. IPA(key): /tu˧/ From Proto-Hmong-Mien *tɛŋH (“to snap”). tu to snap, break apart tu to look after, care for, prepare to clean, clear Heimbach, Ernest E. (1979) White Hmong — English Dictionary‎[15], SEAP Publications, →ISBN, pages 324-5. tu water Carl Campbell, Jody Campbell, Yale Grammar Essentials (1987), page 4

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TU (time unit) (wikipedia)

A time unit (TU) is a unit of time equal to 1024 microseconds. It was originally introduced in IEEE 802.11-1999 standard and continues to be used in newer issues of the IEEE 802.11 standard. In the 802.11 standards, periods of time are generally described as integral numbers of time units. The unit allows for maintaining intervals that are easy to implement in hardware that has a 1 MHz clock (by dividing the clock signal in half ten times, rather than operating a phase-locked loop or digital divider to divide such a clock signal by 1000). One time unit is equal to one millionth of a kibisecond (1 TU = 10−6 Kis). == See also == Binary prefix IEEE 1541 Jiffy == References == == External links == IEEE 802 Standards available via IEEE Get Program IEEE 802.11 Tutorial

A time unit (TU) is a unit of time equal to 1024 microseconds. It was originally introduced in IEEE 802.11-1999 standard and continues to be used in newer issues of the IEEE 802.11 standard. In the 802.11 standards, periods of time are generally described as integral numbers of time units. The unit allows for maintaining intervals that are easy to implement in hardware that has a 1 MHz clock (by dividing the clock signal in half ten times, rather than operating a phase-locked loop or digital divider to divide such a clock signal by 1000). One time unit is equal to one millionth of a kibisecond (1 TU = 10−6 Kis).

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TU (union) (wikipedia)

T-Mobile Workers United (TU) is an organization of T-Mobile USA and Metro by T-Mobile employees joining together for a voice and fair treatment at work. It represents currently 500 members and is affiliated with the Communications Workers of America (CWA) and Vereinte Dienstleistungsgewerkschaft (ver.di), a large German service-sector union. TU is also supported by a coalition of community and labor groups around the world. In July, 2011, technicians in Connecticut, voted for representation by the Communications Workers of America-TU (CWA-TU). On September 25, 2013, MetroPCS workers in Harlem, NY, voted for a union voice and representation by CWA-TU. == History == T-Mobile US is a subsidiary of Deutsche Telekom, the largest telecommunications company in Europe. Through its subsidiary companies, Deutsche Telekom has operations in around 50 countries worldwide. In Germany, Austria, and the Netherlands, employees are represented by trade unions. When Deutsche Telekom purchased VoiceStream Wireless in 2001, the CWA helped the company gain approval for access to the U.S. market, with the expectation that Deutsche Telekom would be open to letting employees freely choose union representation in the United States. The relationship between CWA and T-Mobile US has since eroded. Since it entered the American market in 2001, T-Mobile US has been repeatedly criticized for its employment relations by CWA, ver.di, and other groups. Likewise, American Rights at Work and Human Rights Watch have issued studies of union intolerance at the company’s facilities. In April 2008, CWA and ver.di formed a joint organization for T-Mobile workers named TU. The new organization was "formed with the goal of overcoming the double standard of Deutsche Telekom recognizing labor rights in Germany but ignoring them in the U.S. This new global union is an effective answer to cross-border investment and the globalization of work." When CWA and ver.di created the joint organization, they originally named it “T-Union”. However, Deutsche Telekom threatened to sue the organizations for trademark infringement, since they had trademarked the concept of branding their services with a leading "T-" (as they did with the color magenta). So, CWA and ver.di had to rename the union TU for T-Mobile Workers Union. In August, 2013, TU launched a new website that allows workers at T-Mobile and MetroPCS to connect with each other to build strength in their drive for workplace justice and respect. == TU Affiliates == Ver.di Ver.di represents 2.3 million workers in Germany, including Deutsche Telekom employees. Ver.di was formed in 2001 when the German Salaried Employees' Union (DAG) merged with four unions of the German Confederation of Trade Unions (DGB). Ver.di members work in financial services, utilities, health, social services, education, science and research, federal government, media, printing, telecommunications, postal services, logistics, and transport, among other sectors. The headquarters of the trade union is in Berlin. The Communications Workers of America CWA represents 700,000 workers in the United States, Canada, and Puerto Rico. The union was established in 1947 and affiliated with the Congress of Industrial Organizations in 1949. CWA represents workers in telecommunications, publishing, the airline industry, public safety, healthcare, education, social work, and broadcasting, among many other industries. It is headquartered in Washington, D.C. == TU Workplace Partnerships == To bring together T-Mobile workers in Germany (Deutsche Telekom) and the United States (T-Mobile US), TU has created a workplace partnership program that connects German and American workplaces. These partnerships build solidarity and allow workers to join together to make positive change in the workplace and respond to bad behavior by management. So far, there are 6 partnerships between German and American call center representatives, retail associates and technicians. == Further reading == Compa, Lance, "Free Speech and Freedom of Associuation. Finding the Balance. A Position Paper of the International Trade Union Confederation.", Brussels: International Trade Union Confederation, 2013. Compa, Lance, "A Strange Case: Violations of Workers' Freedom of Association in the United States by European Multinational Corporations." New York: Human Rights Watch, 2010. Logan, John. "Lowering the Bar or Setting The Standard. Deutsche Telekom’s U.S. Labor Practices." Washington, D.C.: American Rights at Work Education Fund, 2009. == References == == External links == === Official websites === Tmobileworkersunited.org – Website for T-Mobile workers Communications Workers of America ver.di === Other Sources === LoweringTheBarForUs.org – Website with news and information about the T-Mobile campaign.

T-Mobile Workers United (TU) is an organization of T-Mobile USA and Metro by T-Mobile employees joining together for a voice and fair treatment at work. It represents currently 500 members and is affiliated with the Communications Workers of America (CWA) and Vereinte Dienstleistungsgewerkschaft (ver.di), a large German service-sector union. TU is also supported by a coalition of community and labor groups around the world. In July, 2011, technicians in Connecticut, voted for representation by the Communications Workers of America-TU (CWA-TU). On September 25, 2013, MetroPCS workers in Harlem, NY, voted for a union voice and representation by CWA-TU.

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tu

Tu (American band) (wikipedia)

TU is an American duo made up of King Crimson members Trey Gunn and Pat Mastelotto in 2002. They have released an official bootleg album, one studio album, one EP, and one live album. The duo's music is largely based on improvisation, sampling, and jazz elements. Gunn and Mastelotto are also members of the supergroup KTU. TU opened for Tool on the band's 10,000 Days tour on a few dates. == Discography == Official Bootleg (2005) Tu (2007) Thunderbird Suite (EP - 2007) Tu (Live in Russia) (2011) == References == == External links == Trey Gunn official website Pat Mastelotto official website

TU is an American duo made up of King Crimson members Trey Gunn and Pat Mastelotto in 2002. They have released an official bootleg album, one studio album, one EP, and one live album. The duo's music is largely based on improvisation, sampling, and jazz elements. Gunn and Mastelotto are also members of the supergroup KTU. TU opened for Tool on the band's 10,000 Days tour on a few dates.

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Tu (Umberto Tozzi song) (wikipedia)

"Tu" is a song written by Umberto Tozzi and Giancarlo Bigazzi and recorded by Tozzi in 1978. Along with "Ti amo" and "Gloria", it is his most successful and well-known song. == Charts == == Year-End chart == == Sales == == References ==

"Tu" is a song written by Umberto Tozzi and Giancarlo Bigazzi and recorded by Tozzi in 1978. Along with "Ti amo" and "Gloria", it is his most successful and well-known song.

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Tu (cake) (wikipedia)

In Tibetan cuisine, Tu is a cheese cake, made with yak butter, brown sugar and water, made into a pastry. == See also == List of pastries List of Tibetan dishes == References ==

In Tibetan cuisine, Tu is a cheese cake, made with yak butter, brown sugar and water, made into a pastry.

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Tu (clothing) (wikipedia)

Tu is a British own-brand fashion label from the supermarket Sainsbury's. It is the United Kingdom's third largest online clothing retailer and the United Kingdom's sixth largest clothing retailer by volume. == Product range == Tu sells a wide range of clothing for men, women and children, with 3,000 lines sold through 400 Sainsbury's supermarkets. == History == The Tu brand was founded in 2004 by Sainsbury's as a replacement for the Jeff & Co range designed by Jeff Banks. The new brand included a line of childrenswear created by Adams. It was initially launched in 160 stores. The original range included both clothing under the "TU" brand and homewares under the brand "TU Home". In 2011, Sainsbury's entered into a partnership with the television clothing guru Gok Wan to design a new clothing range. In 2013, Sainsbury's relaunched the Tu brand, concentrating it entirely on clothing, with the homewares re-branded under the core "by Sainsbury's" brand (the Sainsbury's homewares range is now branded as Habitat as of 2021). The logo was also changed, from all uppercase letters to a capital "T" and a lowercase "u", to emphasise that the brand is pronounced like "two" and not "tea you". In 2015, Sainsbury's set up a dedicated website, tuclothing.sainsburys.co.uk (branded as Tu.co.uk), to sell the product range nationwide to a much bigger audience. Following Sainsbury's acquisition of Argos in 2016, Sainsbury's started selling Tu clothing on the Argos website in 2018. This brought a much larger demographic of shoppers to the Tu brand, enabling access to a much broader range of household incomes. == References == == External links == Official website

Tu is a British own-brand fashion label from the supermarket Sainsbury's. It is the United Kingdom's third largest online clothing retailer and the United Kingdom's sixth largest clothing retailer by volume.

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Tu (cuneiform) (wikipedia)

The cuneiform sign tu, and for TU-(the Sumerogram, capital letter (majuscule), in the Hittite language and other cuneiform texts, is a common-use syllabic sign for tu, and also with a syllabic use for "t", or "u". It is not a multi-use sign, with other alphabetic sub-varieties. The Sumerian-language version is similar to the usage in the Amarna letters, with the three horizontal strokes connecting the four angled wedges on the left, and connected to the vertical horizontal single stroke, at right. Varieties exist: for example, Amarna letter EA 271 shows four horizontal long strokes, with two short strokes, between the two long ones, (see here, 2nd line from bottom (tablet Obverse): [1]. The Hittite language version of tu, (and ideogram TU) is identical in common form to the Sumerian. The composition of the sign is effectively the four-wedge strokes at left, (being še (cuneiform)) connected to the rest of the cuneiform sign. Cuneiform še is also a common-use syllabic sign, with few subvarieties. (Two example angled wedges: ). == Epic of Gilgamesh use == For the Epic of Gilgamesh, the following usage is found in Tablets I-XII: tu (193), tú (2), and TU (9) times. TU is used for the name of the king of Shuruppak (father of Utnapishtim), Ubara-Tutu, and it is spelled: mUBARA-dTU.TU. Two other uses of TU in the Epic are as follows: TU is also the Akkadian language verb, erēbu, for English language 'to enter', 'to set', used in Tablet III and VII. For the Sumerogram TU.MUŠEN, for Akkadian summu, the English 'dove', it is used twice in the Gilgamesh flood myth, Tablet XI. == References == == Further reading == Held, Schmalstieg, Gertz, 1987. Beginning Hittite. Warren H. Held, Jr, William R. Schmalstieg, Janet E. Gertz, c. 1987, Slavica Publishers, Inc. w/ Glossaries, Sign List, Indexes, etc., 218 pages. Moran, William L. 1987, 1992. The Amarna Letters. Johns Hopkins University Press, 1987, 1992. 393 pages.(softcover, ISBN 0-8018-6715-0) Parpola, 1971. The Standard Babylonian Epic of Gilgamesh, Parpola, Simo, Neo-Assyrian Text Corpus Project, c 1997, Tablet I through Tablet XII, Index of Names, Sign List, and Glossary-(pp. 119–145), 165 pages. EA 271 Obverse, "tu", 2nd row from bottom Held, Schmalstieg, Gertz, 1987. Beginning Hittite. Warren H. Held, Jr, William R. Schmalstieg, Janet E. Gertz, c. 1987, Slavica Publishers, Inc. w/ Glossaries, Sign List, Indexes, etc, 218 pages. Moran, William L. 1987, 1992. The Amarna Letters. Johns Hopkins University Press, 1987, 1992. 393 pages.(softcover, ISBN 0-8018-6715-0) Moran, William L. 1987, 1992. The Amarna Letters. EA 147, A Hymn to the Pharaoh, pp. 233-235. Parpola, 1971. The Standard Babylonian Epic of Gilgamesh, Parpola, Simo, Neo-Assyrian Text Corpus Project, c 1997, Tablet I through Tablet XII, Index of Names, Sign List, and Glossary-(pp. 119–145), 165 pages. Rainey, 1970. El Amarna Tablets, 359-379, Anson F. Rainey, (AOAT 8, Alter Orient Altes Testament 8, Kevelaer and Neukirchen -Vluyen), 1970, 107 pages. Parpola, 1971. The Standard Babylonian Epic of Gilgamesh, Sign List, pp. 155-165, no. 068, p. 156. Rainey, 1970. El Amarna Tablets, 359-379, Glossary:Vocabulary, pp. 55-87, p. 24. Rainey, 1970. El Amarna Tablets, 359-379, EA 365, Biridiya of Megiddo to the King, pp. 24-27. Parpola, 1971. The Standard Babylonian Epic of Gilgamesh, Glossary, pp. 119-145, aššum, p. 122. Rainey, 1970. El Amarna Tablets, 359-379, Glossary:Vocabulary, saparu, pp. 55-87, p. 81. Buccellatti, Giorgio, (Ugarit-Forschungen 11, 1979). Comparative Graphemic Analysis of Old Babylonian and Western Akkadian, pp. 95-100. Ugarit Forschungen (Neukirchen-Vluyn). UF-11 (1979) honors Claude Schaeffer, with about 100 articles in 900 pages. pp 95, ff, "Comparative Graphemic Analysis of Old Babylonian and Western Akkadian", ( i.e. Ugarit and Amarna (letters), three others, Mari, OB,Royal, OB,non-Royal letters). See above, in text. Buccellatti, Giorgio. Comparative Graphemic Analysis of Old Babylonian and Western Akkadian, from Ugarit-Forschungen 8, (Neukirchen-Vluyen). Rainey, 1970. El Amarna Tablets, 359-379, Anson F. Rainey, (AOAT 8, Alter Orient Altes Testament 8, Kevelaer and Neukirchen -Vluyen), 1970, 107 pages. Held, Schmalstieg, Gertz, 1987. Beginning Hittite, Sign List, page 194, page 200. Rainey, 1970. El Amarna Tablets, 359-379, Anson F. Rainey, (AOAT 8, Alter Orient Altes Testament 8, Kevelaer and Neukirchen -Vluyen), 1970, 107 pages. Moran, William L. 1987, 1992. The Amarna Letters. Johns Hopkins University Press, 1987, 1992. 393 pages.(softcover, ISBN 0-8018-6715-0)) Rainey, 1970. El Amarna Tablets, 359-379, EA 365, Biridiya of Megiddo to the King, pp. 24-27.

The cuneiform sign tu, and for TU-(the Sumerogram, capital letter (majuscule), in the Hittite language and other cuneiform texts, is a common-use syllabic sign for tu, and also with a syllabic use for "t", or "u". It is not a multi-use sign, with other alphabetic sub-varieties. The Sumerian-language version is similar to the usage in the Amarna letters, with the three horizontal strokes connecting the four angled wedges on the left, and connected to the vertical horizontal single stroke, at right. Varieties exist: for example, Amarna letter EA 271 shows four horizontal long strokes, with two short strokes, between the two long ones, (see here, 2nd line from bottom (tablet Obverse): [1]. The Hittite language version of tu, (and ideogram TU) is identical in common form to the Sumerian. The composition of the sign is effectively the four-wedge strokes at left, (being še (cuneiform)) connected to the rest of the cuneiform sign. Cuneiform še is also a common-use syllabic sign, with few subvarieties. (Two example angled wedges: ).

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Tu (surname) (wikipedia)

Tu (Chinese: 屠; pinyin: Tú) is a Chinese surname, and the 279th family name in Hundred Family Surnames (百家姓). Tu (涂 or 凃) is another Chinese surname. == Origin == From one of the characters in the name of the ancient city of Zoutu. The legendary emperor Yellow Emperor (2697–2595 BC) used this city as a military base. == People with the surname Tu == === People with the surname Tu (屠) === Tu Qihua (屠玘華; 1914–2004), birth-name of the 20th century author Mei Zhi Tu Youyou (屠呦呦; born 1930), Chinese medical scientist, winner of the 2011 Lasker Award and the 2015 Nobel Prize in Physiology or Medicine Tu Jida (屠基达; 1927–2011), aircraft designer, "father of the Chengdu J-7" fighter === People with the surname Tu (涂) === Thor Chuan Leong (涂振龙; born 1988), Malaysian professional snooker player Tu Mingjing (涂铭旌) (1928–2019), Chinese materials scientist Twu Shiing-jer (涂醒哲), Mayor of Chiayi City (2014–2018) === Other === Li Tu (born 1996), Australian tennis player == See also == Tú

Tu (Chinese: 屠; pinyin: Tú) is a Chinese surname, and the 279th family name in Hundred Family Surnames (百家姓). Tu (涂 or 凃) is another Chinese surname.

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Decibel (wikipedia)

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.26) or root-power ratio of 101/20 (approximately 1.12). The unit expresses a relative change or an absolute value. In the latter case, the numeric value expresses the ratio of a value to a fixed reference value; when used in this way, the unit symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "V" (e.g., "20 dBV"). Two principal types of scaling of the decibel are in common use. When expressing a power ratio, it is defined as ten times the logarithm with base 10. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level. When expressing root-power quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. The decibel scales differ by a factor of two, so that the related power and root-power levels change by the same value in linear systems, where power is proportional to the square of amplitude. The definition of the decibel originated in the measurement of transmission loss and power in telephony of the early 20th century in the Bell System in the United States. The bel was named in honor of Alexander Graham Bell, but the bel is seldom used. Instead, the decibel is used for a wide variety of measurements in science and engineering, most prominently for sound power in acoustics, in electronics and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels. == History == The decibel originates from methods used to quantify signal loss in telegraph and telephone circuits. Until the mid-1920s, the unit for loss was miles of standard cable (MSC). 1 MSC corresponded to the loss of power over one mile (approximately 1.6 km) of standard telephone cable at a frequency of 5000 radians per second (795.8 Hz), and matched closely the smallest attenuation detectable to a listener. A standard telephone cable was "a cable having uniformly distributed resistance of 88 ohms per loop-mile and uniformly distributed shunt capacitance of 0.054 microfarads per mile" (approximately corresponding to 19 gauge wire). In 1924, Bell Telephone Laboratories received a favorable response to a new unit definition among members of the International Advisory Committee on Long Distance Telephony in Europe and replaced the MSC with the Transmission Unit (TU). 1 TU was defined such that the number of TUs was ten times the base-10 logarithm of the ratio of measured power to a reference power. The definition was conveniently chosen such that 1 TU approximated 1 MSC; specifically, 1 MSC was 1.056 TU. In 1928, the Bell system renamed the TU into the decibel, being one tenth of a newly defined unit for the base-10 logarithm of the power ratio. It was named the bel, in honor of the telecommunications pioneer Alexander Graham Bell. The bel is seldom used, as the decibel was the proposed working unit. The naming and early definition of the decibel is described in the NBS Standard's Yearbook of 1931: Since the earliest days of the telephone, the need for a unit in which to measure the transmission efficiency of telephone facilities has been recognized. The introduction of cable in 1896 afforded a stable basis for a convenient unit and the "mile of standard" cable came into general use shortly thereafter. This unit was employed up to 1923 when a new unit was adopted as being more suitable for modern telephone work. The new transmission unit is widely used among the foreign telephone organizations and recently it was termed the "decibel" at the suggestion of the International Advisory Committee on Long Distance Telephony. The decibel may be defined by the statement that two amounts of power differ by 1 decibel when they are in the ratio of 100.1 and any two amounts of power differ by N decibels when they are in the ratio of 10N(0.1). The number of transmission units expressing the ratio of any two powers is therefore ten times the common logarithm of that ratio. This method of designating the gain or loss of power in telephone circuits permits direct addition or subtraction of the units expressing the efficiency of different parts of the circuit ... In 1954, J. W. Horton argued that the use of the decibel as a unit for quantities other than transmission loss led to confusion, and suggested the name logit for "standard magnitudes which combine by multiplication", to contrast with the name unit for "standard magnitudes which combine by addition". In April 2003, the International Committee for Weights and Measures (CIPM) considered a recommendation for the inclusion of the decibel in the International System of Units (SI), but decided against the proposal. However, the decibel is recognized by other international bodies such as the International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO). The IEC permits the use of the decibel with root-power quantities as well as power and this recommendation is followed by many national standards bodies, such as NIST, which justifies the use of the decibel for voltage ratios. In spite of their widespread use, suffixes (such as in dBA or dBV) are not recognized by the IEC or ISO. == Definition == ISO 80000-3 describes definitions for quantities and units of space and time. The IEC Standard 60027-3:2002 defines the following quantities. The decibel (dB) is one-tenth of a bel: 1 dB = 0.1 B. The bel (B) is 1⁄2 ln(10) nepers: 1 B = 1⁄2 ln(10) Np. The neper is the change in the level of a root-power quantity when the root-power quantity changes by a factor of e, that is 1 Np = ln(e) = 1, thereby relating all of the units as nondimensional natural log of root-power-quantity ratios, 1 dB = 0.11513... Np = 0.11513.... Finally, the level of a quantity is the logarithm of the ratio of the value of that quantity to a reference value of the same kind of quantity. Therefore, the bel represents the logarithm of a ratio between two power quantities of 10:1, or the logarithm of a ratio between two root-power quantities of √10:1. Two signals whose levels differ by one decibel have a power ratio of 101/10, which is approximately 1.25893, and an amplitude (root-power quantity) ratio of 101/20 (1.12202). The bel is rarely used either without a prefix or with SI unit prefixes other than deci; it is preferred, for example, to use hundredths of a decibel rather than millibels. Thus, five one-thousandths of a bel would normally be written 0.05 dB, and not 5 mB. The method of expressing a ratio as a level in decibels depends on whether the measured property is a power quantity or a root-power quantity; see Power, root-power, and field quantities for details. === Power quantities === When referring to measurements of power quantities, a ratio can be expressed as a level in decibels by evaluating ten times the base-10 logarithm of the ratio of the measured quantity to reference value. Thus, the ratio of P (measured power) to P0 (reference power) is represented by LP, that ratio expressed in decibels, which is calculated using the formula: L P = 1 2 ln ( P P 0 ) Np = 10 log 10 ( P P 0 ) dB . {\displaystyle L_{P}={\frac {1}{2}}\ln \!\left({\frac {P}{P_{0}}}\right)\,{\text{Np}}=10\log _{10}\!\left({\frac {P}{P_{0}}}\right)\,{\text{dB}}.} The base-10 logarithm of the ratio of the two power quantities is the number of bels. The number of decibels is ten times the number of bels (equivalently, a decibel is one-tenth of a bel). P and P0 must measure the same type of quantity, and have the same units before calculating the ratio. If P = P0 in the above equation, then LP = 0. If P is greater than P0 then LP is positive; if P is less than P0 then LP is negative. Rearranging the above equation gives the following formula for P in terms of P0 and LP: P = 10 L P 10 dB P 0 . {\displaystyle P=10^{\frac {L_{P}}{10\,{\text{dB}}}}P_{0}.} === Root-power (field) quantities === When referring to measurements of root-power quantities, it is usual to consider the ratio of the squares of F (measured) and F0 (reference). This is because the definitions were originally formulated to give the same value for relative ratios for both power and root-power quantities. Thus, the following definition is used: L F = ln ( F F 0 ) Np = 10 log 10 ( F 2 F 0 2 ) dB = 20 log 10 ⁡ ( F F 0 ) dB . {\displaystyle L_{F}=\ln \!\left({\frac {F}{F_{0}}}\right)\,{\text{Np}}=10\log _{10}\!\left({\frac {F^{2}}{F_{0}^{2}}}\right)\,{\text{dB}}=20\log _{10}\left({\frac {F}{F_{0}}}\right)\,{\text{dB}}.} The formula may be rearranged to give F = 10 L F 20 dB F 0 . {\displaystyle F=10^{\frac {L_{F}}{20\,{\text{dB}}}}F_{0}.} Similarly, in electrical circuits, dissipated power is typically proportional to the square of voltage or current when the impedance is constant. Taking voltage as an example, this leads to the equation for power gain level LG: L G = 20 log 10 ( V out V in ) dB , {\displaystyle L_{G}=20\log _{10}\!\left({\frac {V_{\text{out}}}{V_{\text{in}}}}\right)\,{\text{dB}},} where Vout is the root-mean-square (rms) output voltage, Vin is the rms input voltage. A similar formula holds for current. The term root-power quantity is introduced by ISO Standard 80000-1:2009 as a substitute of field quantity. The term field quantity is deprecated by that standard and root-power is used throughout this article. === Relationship between power and root-power levels === Although power and root-power quantities are different quantities, their respective levels are historically measured in the same units, typically decibels. A factor of 2 is introduced to make changes in the respective levels match under restricted conditions such as when the medium is linear and the same waveform is under consideration with changes in amplitude, or the medium impedance is linear and independent of both frequency and time. This relies on the relationship P ( t ) P 0 = ( F ( t ) F 0 ) 2 {\displaystyle {\frac {P(t)}{P_{0}}}=\left({\frac {F(t)}{F_{0}}}\right)^{2}} holding. In a nonlinear system, this relationship does not hold by the definition of linearity. However, even in a linear system in which the power quantity is the product of two linearly related quantities (e.g. voltage and current), if the impedance is frequency- or time-dependent, this relationship does not hold in general, for example if the energy spectrum of the waveform changes. For differences in level, the required relationship is relaxed from that above to one of proportionality (i.e., the reference quantities P0 and F0 need not be related), or equivalently, P 2 P 1 = ( F 2 F 1 ) 2 {\displaystyle {\frac {P_{2}}{P_{1}}}=\left({\frac {F_{2}}{F_{1}}}\right)^{2}} must hold to allow the power level difference to be equal to the root-power level difference from power P1 and F1 to P2 and F2. An example might be an amplifier with unity voltage gain independent of load and frequency driving a load with a frequency-dependent impedance: the relative voltage gain of the amplifier is always 0 dB, but the power gain depends on the changing spectral composition of the waveform being amplified. Frequency-dependent impedances may be analyzed by considering the quantities power spectral density and the associated root-power quantities via the Fourier transform, which allows elimination of the frequency dependence in the analysis by analyzing the system at each frequency independently. === Conversions === Since logarithm differences measured in these units often represent power ratios and root-power ratios, values for both are shown below. The bel is traditionally used as a unit of logarithmic power ratio, while the neper is used for logarithmic root-power (amplitude) ratio. === Examples === The unit dBW is often used to denote a ratio for which the reference is 1 W, and similarly dBm for a 1 mW reference point. Calculating the ratio in decibels of 1 kW (one kilowatt, or 1000 watts) to 1 W yields: L G = 10 log 10 ⁡ ( 1 000 W 1 W ) dB = 30 dB . {\displaystyle L_{G}=10\log _{10}\left({\frac {1\,000\,{\text{W}}}{1\,{\text{W}}}}\right)\,{\text{dB}}=30\,{\text{dB}}.} The ratio in decibels of √1000 V ≈ 31.62 V to 1 V is L G = 20 log 10 ⁡ ( 31.62 V 1 V ) dB = 30 dB . {\displaystyle L_{G}=20\log _{10}\left({\frac {31.62\,{\text{V}}}{1\,{\text{V}}}}\right)\,{\text{dB}}=30\,{\text{dB}}.} (31.62 V / 1 V)2 ≈ 1 kW / 1 W, illustrating the consequence from the definitions above that LG has the same value, 30 dB, regardless of whether it is obtained from powers or from amplitudes, provided that in the specific system being considered power ratios are equal to amplitude ratios squared. The ratio in decibels of 10 W to 1 mW (one milliwatt) is obtained with the formula L G = 10 log 10 ⁡ ( 10 W 0.001 W ) dB = 40 dB . {\displaystyle L_{G}=10\log _{10}\left({\frac {10{\text{ W}}}{0.001{\text{ W}}}}\right){\text{ dB}}=40{\text{ dB}}.} The power ratio corresponding to a 3 dB change in level is given by G = 10 3 10 × 1 = 1.995 26 … ≈ 2. {\displaystyle G=10^{\frac {3}{10}}\times 1=1.995\,26\ldots \approx 2.} A change in power ratio by a factor of 10 corresponds to a change in level of 10 dB. A change in power ratio by a factor of 2 or 1/2 is approximately a change of 3 dB. More precisely, the change is ±3.0103 dB, but this is almost universally rounded to 3 dB in technical writing. This implies an increase in voltage by a factor of √2 ≈ 1.4142. Likewise, a doubling or halving of the voltage, corresponding to a quadrupling or quartering of the power, is commonly described as 6 dB rather than ±6.0206 dB. Should it be necessary to make the distinction, the number of decibels is written with additional significant figures. 3.000 dB corresponds to a power ratio of 103/10, or 1.9953, about 0.24% different from exactly 2, and a voltage ratio of 1.4125, 0.12% different from exactly √2. Similarly, an increase of 6.000 dB corresponds to the power ratio is 106/10 ≈ 3.9811, about 0.5% different from 4. == Properties == The decibel is useful for representing large ratios and for simplifying representation of multiplicative effects, such as attenuation from multiple sources along a signal chain. Its application in systems with additive effects is less intuitive, such as in the combined sound pressure level of two machines operating together. Care is also necessary with decibels directly in fractions and with the units of multiplicative operations. === Reporting large ratios === The logarithmic scale nature of the decibel means that a very large range of ratios can be represented by a convenient number, in a manner similar to scientific notation. This allows one to clearly visualize huge changes of some quantity. See Bode plot and Semi-log plot. For example, 120 dB SPL may be clearer than "a trillion times more intense than the threshold of hearing". === Representation of multiplication operations === Level values in decibels can be added instead of multiplying the underlying power values, which means that the overall gain of a multi-component system, such as a series of amplifier stages, can be calculated by summing the gains in decibels of the individual components, rather than multiply the amplification factors; that is, log(A × B × C) = log(A) + log(B) + log(C). Practically, this means that, armed only with the knowledge that 1 dB is a power gain of approximately 26%, 3 dB is approximately 2× power gain, and 10 dB is 10× power gain, it is possible to determine the power ratio of a system from the gain in dB with only simple addition and multiplication. For example: A system consists of 3 amplifiers in series, with gains (ratio of power out to in) of 10 dB, 8 dB, and 7 dB respectively, for a total gain of 25 dB. Broken into combinations of 10, 3, and 1 dB, this is: With an input of 1 watt, the output is approximately Calculated precisely, the output is 1 W × 1025/10 ≈ 316.2 W. The approximate value has an error of only +0.4% with respect to the actual value, which is negligible given the precision of the values supplied and the accuracy of most measurement instrumentation. However, according to its critics, the decibel creates confusion, obscures reasoning, is more related to the era of slide rules than to modern digital processing, and is cumbersome and difficult to interpret. Quantities in decibels are not necessarily additive, thus being "of unacceptable form for use in dimensional analysis". Thus, units require special care in decibel operations. Take, for example, carrier-to-noise-density ratio C/N0 (in hertz), involving carrier power C (in watts) and noise power spectral density N0 (in W/Hz). Expressed in decibels, this ratio would be a subtraction (C/N0)dB = CdB − N0dB. However, the linear-scale units still simplify in the implied fraction, so that the results would be expressed in dB-Hz. === Representation of addition operations === According to Mitschke, "The advantage of using a logarithmic measure is that in a transmission chain, there are many elements concatenated, and each has its own gain or attenuation. To obtain the total, addition of decibel values is much more convenient than multiplication of the individual factors." However, for the same reason that humans excel at additive operation over multiplication, decibels are awkward in inherently additive operations:if two machines each individually produce a sound pressure level of, say, 90 dB at a certain point, then when both are operating together we should expect the combined sound pressure level to increase to 93 dB, but certainly not to 180 dB!; suppose that the noise from a machine is measured (including the contribution of background noise) and found to be 87 dBA but when the machine is switched off the background noise alone is measured as 83 dBA. [...] the machine noise [level (alone)] may be obtained by 'subtracting' the 83 dBA background noise from the combined level of 87 dBA; i.e., 84.8 dBA.; in order to find a representative value of the sound level in a room a number of measurements are taken at different positions within the room, and an average value is calculated. [...] Compare the logarithmic and arithmetic averages of [...] 70 dB and 90 dB: logarithmic average = 87 dB; arithmetic average = 80 dB. Addition on a logarithmic scale is called logarithmic addition, and can be defined by taking exponentials to convert to a linear scale, adding there, and then taking logarithms to return. For example, where operations on decibels are logarithmic addition/subtraction and logarithmic multiplication/division, while operations on the linear scale are the usual operations: 87 dBA ⊖ 83 dBA = 10 ⋅ log 10 ⁡ ( 10 87 / 10 − 10 83 / 10 ) dBA ≈ 84.8 dBA {\displaystyle 87\,{\text{dBA}}\ominus 83\,{\text{dBA}}=10\cdot \log _{10}{\bigl (}10^{87/10}-10^{83/10}{\bigr )}\,{\text{dBA}}\approx 84.8\,{\text{dBA}}} M lm ( 70 , 90 ) = ( 70 dBA + 90 dBA ) / 2 = 10 ⋅ log 10 ⁡ ( ( 10 70 / 10 + 10 90 / 10 ) / 2 ) dBA = 10 ⋅ ( log 10 ⁡ ( 10 70 / 10 + 10 90 / 10 ) − log 10 ⁡ 2 ) dBA ≈ 87 dBA . {\displaystyle {\begin{aligned}M_{\text{lm}}(70,90)&=\left(70\,{\text{dBA}}+90\,{\text{dBA}}\right)/2\\&=10\cdot \log _{10}\left({\bigl (}10^{70/10}+10^{90/10}{\bigr )}/2\right)\,{\text{dBA}}\\&=10\cdot \left(\log _{10}{\bigl (}10^{70/10}+10^{90/10}{\bigr )}-\log _{10}2\right)\,{\text{dBA}}\approx 87\,{\text{dBA}}.\end{aligned}}} The logarithmic mean is obtained from the logarithmic sum by subtracting 10 log 10 ⁡ 2 {\displaystyle 10\log _{10}2} , since logarithmic division is linear subtraction. === Fractions === Attenuation constants, in topics such as optical fiber communication and radio propagation path loss, are often expressed as a fraction or ratio to distance of transmission. In this case, dB/m represents decibel per meter, dB/mi represents decibel per mile, for example. These quantities are to be manipulated obeying the rules of dimensional analysis, e.g., a 100-meter run with a 3.5 dB/km fiber yields a loss of 0.35 dB = 3.5 dB/km × 0.1 km. == Uses == === Perception === The human perception of the intensity of sound and light more nearly approximates the logarithm of intensity rather than a linear relationship (see Weber–Fechner law), making the dB scale a useful measure. === Acoustics === The decibel is commonly used in acoustics as a unit of sound power level or sound pressure level. The reference pressure for sound in air is set at the typical threshold of perception of an average human and there are common comparisons used to illustrate different levels of sound pressure. As sound pressure is a root-power quantity, the appropriate version of the unit definition is used: L p = 20 log 10 ( p rms p ref ) dB , {\displaystyle L_{p}=20\log _{10}\!\left({\frac {p_{\text{rms}}}{p_{\text{ref}}}}\right)\,{\text{dB}},} where prms is the root mean square of the measured sound pressure and pref is the standard reference sound pressure of 20 micropascals in air or 1 micropascal in water. Use of the decibel in underwater acoustics leads to confusion, in part because of this difference in reference value. Sound intensity is proportional to the square of sound pressure. Therefore the sound intensity level can also be defined as: L p = 10 log 10 ( I I ref ) dB , {\displaystyle L_{p}=10\log _{10}\!\left({\frac {I}{I_{\text{ref}}}}\right)\,{\text{dB}},} The human ear has a large dynamic range in sound reception. The ratio of the sound intensity that causes permanent damage during short exposure to that of the quietest sound that the ear can hear is equal to or greater than 1 trillion (1012). Such large measurement ranges are conveniently expressed in logarithmic scale: the base-10 logarithm of 1012 is 12, which is expressed as a sound intensity level of 120 dB re 1 pW/m2. The reference values of I and p in air have been chosen such that this corresponds approximately to a sound pressure level of 120 dB re 20 μPa. Since the human ear is not equally sensitive to all sound frequencies, the acoustic power spectrum is modified by frequency weighting (A-weighting being the most common standard) to get the weighted acoustic power before converting to a sound level or noise level in decibels. === Telephony === The decibel is used in telephony and audio. Similarly to the use in acoustics, a frequency weighted power is often used. For audio noise measurements in electrical circuits, the weightings are called psophometric weightings. === Electronics === In electronics, the decibel is often used to express power or amplitude ratios (as for gains) in preference to arithmetic ratios or percentages. One advantage is that the total decibel gain of a series of components (such as amplifiers and attenuators) can be calculated simply by summing the decibel gains of the individual components. Similarly, in telecommunications, decibels denote signal gain or loss from a transmitter to a receiver through some medium (free space, waveguide, coaxial cable, fiber optics, etc.) using a link budget. The decibel unit can also be combined with a reference level, often indicated via a suffix, to create an absolute unit of electric power. For example, it can be combined with "m" for "milliwatt" to produce the "dBm". A power level of 0 dBm corresponds to one milliwatt, and 1 dBm is one decibel greater (about 1.259 mW). In professional audio specifications, a popular unit is the dBu. This is relative to the root mean square voltage which delivers 1 mW (0 dBm) into a 600-ohm resistor, or √1 mW×600 Ω ≈ 0.775 VRMS. When used in a 600-ohm circuit (historically, the standard reference impedance in telephone circuits), dBu and dBm are identical. === Optics === In an optical link, if a known amount of optical power, in dBm (referenced to 1 mW), is launched into a fiber, and the losses, in dB (decibels), of each component (e.g., connectors, splices, and lengths of fiber) are known, the overall link loss may be quickly calculated by addition and subtraction of decibel quantities. In spectrometry and optics, the blocking unit used to measure optical density is equivalent to −1 B. === Video and digital imaging === In connection with video and digital image sensors, decibels generally represent ratios of video voltages or digitized light intensities, using 20 log of the ratio, even when the represented intensity (optical power) is directly proportional to the voltage generated by the sensor, not to its square, as in a CCD imager where response voltage is linear in intensity. Thus, a camera signal-to-noise ratio or dynamic range quoted as 40 dB represents a ratio of 100:1 between optical signal intensity and optical-equivalent dark-noise intensity, not a 10,000:1 intensity (power) ratio as 40 dB might suggest. Sometimes the 20 log ratio definition is applied to electron counts or photon counts directly, which are proportional to sensor signal amplitude without the need to consider whether the voltage response to intensity is linear. However, as mentioned above, the 10 log intensity convention prevails more generally in physical optics, including fiber optics, so the terminology can become murky between the conventions of digital photographic technology and physics. Most commonly, quantities called "dynamic range" or "signal-to-noise" (of the camera) would be specified in 20 log dB, but in related contexts (e.g. attenuation, gain, intensifier SNR, or rejection ratio) the term should be interpreted cautiously, as confusion of the two units can result in very large misunderstandings of the value. Photographers typically use an alternative base-2 log unit, the stop, to describe light intensity ratios or dynamic range. == Suffixes and reference values == Suffixes are commonly attached to the basic dB unit in order to indicate the reference value by which the ratio is calculated. For example, dBm indicates power measurement relative to 1 milliwatt. In cases where the unit value of the reference is stated, the decibel value is known as "absolute". If the unit value of the reference is not explicitly stated, as in the dB gain of an amplifier, then the decibel value is considered relative. This form of attaching suffixes to dB is widespread in practice, albeit being against the rules promulgated by standards bodies (ISO and IEC), given the "unacceptability of attaching information to units" and the "unacceptability of mixing information with units". The IEC 60027-3 standard recommends the following format: Lx (re xref) or as Lx/xref, where x is the quantity symbol and xref is the value of the reference quantity, e.g., LE (re 1 μV/m) = 20 dB or LE/(1 μV/m) = 20 dB for the electric field strength E relative to 1 μV/m reference value. If the measurement result 20 dB is presented separately, it can be specified using the information in parentheses, which is then part of the surrounding text and not a part of the unit: 20 dB (re: 1 μV/m) or 20 dB (1 μV/m). Outside of documents adhering to SI units, the practice is very common as illustrated by the following examples. There is no general rule, with various discipline-specific practices. Sometimes the suffix is a unit symbol ("W","K","m"), sometimes it is a transliteration of a unit symbol ("uV" instead of μV for microvolt), sometimes it is an acronym for the unit's name ("sm" for square meter, "m" for milliwatt), other times it is a mnemonic for the type of quantity being calculated ("i" for antenna gain with respect to an isotropic antenna, "λ" for anything normalized by the EM wavelength), or otherwise a general attribute or identifier about the nature of the quantity ("A" for A-weighted sound pressure level). The suffix is often connected with a hyphen, as in "dB‑Hz", or with a space, as in "dB HL", or enclosed in parentheses, as in "dB(sm)", or with no intervening character, as in "dBm" (which is non-compliant with international standards). == List of suffixes == === Voltage === Since the decibel is defined with respect to power, not amplitude, conversions of voltage ratios to decibels must square the amplitude, or use the factor of 20 instead of 10, as discussed above. dBV dB(VRMS) – voltage relative to 1 volt, regardless of impedance. This is used to measure microphone sensitivity, and also to specify the consumer line-level of −10 dBV, in order to reduce manufacturing costs relative to equipment using a +4 dBu line-level signal. dBu or dBv RMS voltage relative to V = 600 Ω ⋅ 0.001 W ≈ 0.7746 V {\displaystyle V={\sqrt {600\,\Omega \cdot 0.001\,{\text{W}}}}\approx 0.7746\,{\text{V}}} (i.e. the voltage that would dissipate 1 mW into a 600 Ω load). An RMS voltage of 1 V therefore corresponds to 20 ⋅ log 10 ⁡ ( 1 V RMS 0.6 V ) = 2.218 dBu . {\displaystyle 20\cdot \log _{10}\left({\frac {1\,V_{\text{RMS}}}{{\sqrt {0.6}}\,V}}\right)=2.218\,{\text{dBu}}.} Originally dBv, it was changed to dBu to avoid confusion with dBV. The v comes from volt, while u comes from the volume unit used in the VU meter.dBu can be used as a measure of voltage, regardless of impedance, but is derived from a 600 Ω load dissipating 0 dBm (1 mW). The reference voltage comes from the computation V = R ⋅ P {\displaystyle V={\sqrt {R\cdot P}}} where R {\displaystyle R} is the resistance and P {\displaystyle P} is the power. In professional audio, equipment may be calibrated to indicate a "0" on the VU meters some finite time after a signal has been applied at an amplitude of +4 dBu. Consumer equipment typically uses a lower "nominal" signal level of −10 dBV. Therefore, many devices offer dual voltage operation (with different gain or "trim" settings) for interoperability reasons. A switch or adjustment that covers at least the range between +4 dBu and −10 dBV is common in professional equipment. dBm0s Defined by Recommendation ITU-R V.574.; dBmV: dB(mVRMS) – voltage relative to 1 millivolt across 75 Ω. Widely used in cable television networks, where the nominal strength of a single TV signal at the receiver terminals is about 0 dBmV. Cable TV uses 75 Ω coaxial cable, so 0 dBmV corresponds to −78.75 dBW (−48.75 dBm) or approximately 13 nW. dBμV or dBuV dB(μVRMS) – voltage relative to 1 microvolt. Widely used in television and aerial amplifier specifications. 60 dBμV = 0 dBmV. === Acoustics === Probably the most common usage of "decibels" in reference to sound level is dB SPL, sound pressure level referenced to the nominal threshold of human hearing: The measures of pressure (a root-power quantity) use the factor of 20, and the measures of power (e.g. dB SIL and dB SWL) use the factor of 10. dB SPL dB SPL (sound pressure level) – for sound in air and other gases, relative to 20 micropascals (μPa), or 2×10−5 Pa, approximately the quietest sound a human can hear. For sound in water and other liquids, a reference pressure of 1 μPa is used. An RMS sound pressure of one pascal corresponds to a level of 94 dB SPL. dB SIL dB sound intensity level – relative to 10−12 W/m2, which is roughly the threshold of human hearing in air. dB SWL dB sound power level – relative to 10−12 W. dBA, dBB, and dBC These symbols are often used to denote the use of different weighting filters, used to approximate the human ear's response to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and its effects on humans and other animals, and they are widely used in industry while discussing noise control issues, regulations and environmental standards. Other variations that may be seen are dBA or dB(A). According to standards from the International Electro-technical Committee (IEC 61672-2013) and the American National Standards Institute, ANSI S1.4, the preferred usage is to write LA = x dB. Nevertheless, the units dBA and dB(A) are still commonly used as a shorthand for A‑weighted measurements. Compare dBc, used in telecommunications. dB HL dB hearing level is used in audiograms as a measure of hearing loss. The reference level varies with frequency according to a minimum audibility curve as defined in ANSI and other standards, such that the resulting audiogram shows deviation from what is regarded as 'normal' hearing. dB Q sometimes used to denote weighted noise level, commonly using the ITU-R 468 noise weighting dBpp relative to the peak to peak sound pressure. dBG G‑weighted spectrum === Audio electronics === See also dBV and dBu above. dBm dB(mW) – power relative to 1 milliwatt. In audio and telephony, dBm is typically referenced relative to a 600 Ω impedance, which corresponds to a voltage level of 0.775 volts or 775 millivolts. dBm0 Power in dBm (described above) measured at a zero transmission level point. dBFS dB(full scale) – the amplitude of a signal compared with the maximum which a device can handle before clipping occurs. Full-scale may be defined as the power level of a full-scale sinusoid or alternatively a full-scale square wave. A signal measured with reference to a full-scale sine-wave appears 3 dB weaker when referenced to a full-scale square wave, thus: 0 dBFS(fullscale sine wave) = −3 dBFS(fullscale square wave). dBVU dB volume unit dBTP dB(true peak) – peak amplitude of a signal compared with the maximum which a device can handle before clipping occurs. In digital systems, 0 dBTP would equal the highest level (number) the processor is capable of representing. Measured values are always negative or zero, since they are less than or equal to full-scale. === Radar === dBZ dB(Z) – decibel relative to Z = 1 mm6⋅m−3: energy of reflectivity (weather radar), related to the amount of transmitted power returned to the radar receiver. Values above 20 dBZ usually indicate falling precipitation. dBsm dB(m2) – decibel relative to one square meter: measure of the radar cross section (RCS) of a target. The power reflected by the target is proportional to its RCS. "Stealth" aircraft and insects have negative RCS measured in dBsm, large flat plates or non-stealthy aircraft have positive values. === Radio power, energy, and field strength === dBc relative to carrier – in telecommunications, this indicates the relative levels of noise or sideband power, compared with the carrier power. Compare dBC, used in acoustics. dBpp relative to the maximum value of the peak power. dBJ energy relative to 1 joule. 1 joule = 1 watt second = 1 watt per hertz, so power spectral density can be expressed in dBJ. dBm dB(mW) – power relative to 1 milliwatt. In the radio field, dBm is usually referenced to a 50 Ω load, with the resultant voltage being 0.224 volts. dBμV/m, dBuV/m, or dBμ dB(μV/m) – electric field strength relative to 1 microvolt per meter. The unit is often used to specify the signal strength of a television broadcast at a receiving site (the signal measured at the antenna output is reported in dBμV). dBf dB(fW) – power relative to 1 femtowatt. dBW dB(W) – power relative to 1 watt. dBk dB(kW) – power relative to 1 kilowatt. dBe dB electrical. dBo dB optical. A change of 1 dBo in optical power can result in a change of up to 2 dBe in electrical signal power in a system that is thermal noise limited. === Antenna measurements === dBi dB(isotropic) – the gain of an antenna compared with the gain of a theoretical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise. dBd dB(dipole) – the gain of an antenna compared with the gain a half-wave dipole antenna. 0 dBd = 2.15 dBi dBiC dB(isotropic circular) – the gain of an antenna compared to the gain of a theoretical circularly polarized isotropic antenna. There is no fixed conversion rule between dBiC and dBi, as it depends on the receiving antenna and the field polarization. dBq dB(quarterwave) – the gain of an antenna compared to the gain of a quarter wavelength whip. Rarely used, except in some marketing material. 0 dBq = −0.85 dBi dBsm dB(m2) – decibel relative to one square meter: measure of the antenna effective area. dBm−1 dB(m−1) – decibel relative to reciprocal of meter: measure of the antenna factor. === Other measurements === dB‑Hz dB(Hz) – bandwidth relative to one hertz. E.g., 20 dB‑Hz corresponds to a bandwidth of 100 Hz. Commonly used in link budget calculations. Also used in carrier-to-noise-density ratio (not to be confused with carrier-to-noise ratio, in dB). dBov or dBO dB(overload) – the amplitude of a signal (usually audio) compared with the maximum which a device can handle before clipping occurs. Similar to dBFS, but also applicable to analog systems. According to ITU-T Rec. G.100.1 the level in dBov of a digital system is defined as: L ov = 10 log 10 ⁡ ( P P 0 ) [ dBov ] , {\displaystyle L_{\text{ov}}=10\log _{10}\left({\frac {P}{P_{0}}}\right)\ [{\text{dBov}}],} with the maximum signal power P 0 = 1.0 {\displaystyle P_{0}=1.0} , for a rectangular signal with the maximum amplitude x over {\displaystyle x_{\text{over}}} . The level of a tone with a digital amplitude (peak value) of x over {\displaystyle x_{\text{over}}} is therefore L = − 3.01 dBov {\displaystyle L=-3.01\ {\text{dBov}}} . dBr dB(relative) – simply a relative difference from something else, which is made apparent in context. The difference of a filter's response to nominal levels, for instance. dBrn dB above reference noise. See also dBrnC dBrnC dBrnC represents an audio level measurement, typically in a telephone circuit, relative to a -90 dBm reference level, with the measurement of this level frequency-weighted by a standard C-message weighting filter. The C-message weighting filter was chiefly used in North America. The Psophometric filter is used for this purpose on international circuits. See Psophometric weighting to see a comparison of frequency response curves for the C-message weighting and Psophometric weighting filters. dBK dB(K) – decibels relative to 1 K; used to express noise temperature. dB/K dB(K−1) – decibels relative to 1 K−1. — not decibels per kelvin: Used for the G/T factor, a figure of merit utilized in satellite communications, relating the antenna gain G to the receiver system noise equivalent temperature T. === List of suffixes in alphabetical order === ==== Unpunctuated suffixes ==== dBA see dB(A). dBa see dBrn adjusted. dBB see dB(B). dBc relative to carrier – in telecommunications, this indicates the relative levels of noise or sideband power, compared with the carrier power. dBC see dB(C). dBD see dB(D). dBd dB(dipole) – the forward gain of an antenna compared with a half-wave dipole antenna. 0 dBd = 2.15 dBi dBe dB electrical. dBf dB(fW) – power relative to 1 femtowatt. dBFS dB(full scale) – the amplitude of a signal compared with the maximum which a device can handle before clipping occurs. Full-scale may be defined as the power level of a full-scale sinusoid or alternatively a full-scale square wave. A signal measured with reference to a full-scale sine-wave appears 3 dB weaker when referenced to a full-scale square wave, thus: 0 dBFS(fullscale sine wave) = −3 dBFS(fullscale square wave). dBG G-weighted spectrum dBi dB(isotropic) – the forward gain of an antenna compared with the hypothetical isotropic antenna, which uniformly distributes energy in all directions. Linear polarization of the EM field is assumed unless noted otherwise. dBiC dB(isotropic circular) – the forward gain of an antenna compared to a circularly polarized isotropic antenna. There is no fixed conversion rule between dBiC and dBi, as it depends on the receiving antenna and the field polarization. dBJ energy relative to 1 joule. 1 joule = 1 watt second = 1 watt per hertz, so power spectral density can be expressed in dBJ. dBk dB(kW) – power relative to 1 kilowatt. dBK dB(K) – decibels relative to kelvin: Used to express noise temperature. dBm dB(mW) – power relative to 1 milliwatt. dBm0 Power in dBm measured at a zero transmission level point. dBm0s Defined by Recommendation ITU-R V.574. dBmV dB(mVRMS) – voltage relative to 1 millivolt across 75 Ω. dBo dB optical. A change of 1 dBo in optical power can result in a change of up to 2 dBe in electrical signal power in system that is thermal noise limited. dBO see dBov dBov or dBO dB(overload) – the amplitude of a signal (usually audio) compared with the maximum which a device can handle before clipping occurs. dBpp relative to the peak to peak sound pressure. dBpp relative to the maximum value of the peak power. dBq dB(quarterwave) – the forward gain of an antenna compared to a quarter wavelength whip. Rarely used, except in some marketing material. 0 dBq = −0.85 dBi dBr dB(relative) – simply a relative difference from something else, which is made apparent in context. The difference of a filter's response to nominal levels, for instance. dBrn dB above reference noise. See also dBrnC dBrnC dBrnC represents an audio level measurement, typically in a telephone circuit, relative to the circuit noise level, with the measurement of this level frequency-weighted by a standard C-message weighting filter. The C-message weighting filter was chiefly used in North America. dBsm dB(m2) – decibel relative to one square meter dBTP dB(true peak) – peak amplitude of a signal compared with the maximum which a device can handle before clipping occurs. dBu or dBv RMS voltage relative to 0.6 V ≈ 0.7746 V ≈ − 2.218 dBV {\displaystyle {\sqrt {0.6}}\,{\text{V}}\,\approx 0.7746\,{\text{V}}\,\approx -2.218\,{\text{dBV}}} . dBu0s Defined by Recommendation ITU-R V.574. dBuV see dBμV dBuV/m see dBμV/m dBv see dBu dBV dB(VRMS) – voltage relative to 1 volt, regardless of impedance. dBVU dB volume unit dBW dB(W) – power relative to 1 watt. dBW·m−2·Hz−1 spectral density relative to 1 W·m−2·Hz−1 dBZ dB(Z) – decibel relative to Z = 1 mm6⋅m−3 dBμ see dBμV/m dBμV or dBuV dB(μVRMS) – voltage relative to 1 microvolt. dBμV/m, dBuV/m, or dBμ dB(μV/m) – electric field strength relative to 1 microvolt per meter. ==== Suffixes preceded by a space ==== dB HL dB hearing level is used in audiograms as a measure of hearing loss. dB Q sometimes used to denote weighted noise level dB SIL dB sound intensity level – relative to 10−12 W/m2 dB SPL dB SPL (sound pressure level) – for sound in air and other gases, relative to 20 μPa in air or 1 μPa in water dB SWL dB sound power level – relative to 10−12 W. ==== Suffixes within parentheses ==== dB(A), dB(B), dB(C), dB(D), dB(G), and dB(Z) These symbols are often used to denote the use of different weighting filters, used to approximate the human ear's response to sound, although the measurement is still in dB (SPL). These measurements usually refer to noise and its effects on humans and other animals, and they are widely used in industry while discussing noise control issues, regulations and environmental standards. Other variations that may be seen are dBA or dBA. ==== Other suffixes ==== dB-Hz dB(Hz) – bandwidth relative to one hertz. dB/K dB(K−1) – decibels relative to reciprocal of kelvin dBm−1 dB(m−1) – decibel relative to reciprocal of meter: measure of the antenna factor. mBm mB(mW) – power relative to 1 milliwatt, in millibels (one hundredth of a decibel). 100 mBm = 1 dBm. This unit is in the Wi-Fi drivers of the Linux kernel and the regulatory domain sections. == See also == Apparent magnitude Cent (music) Day–evening–night noise level (Lden) and day-night average sound level (Ldl), European and American standards for expressing noise level over an entire day dB drag racing Decade (log scale) Loudness Neper One-third octave § Base 10 pH Phon Richter magnitude scale Sone == Notes == == References == == Further reading == Tuffentsammer, Karl (1956). "Das Dezilog, eine Brücke zwischen Logarithmen, Dezibel, Neper und Normzahlen" [The decilog, a bridge between logarithms, decibel, neper and preferred numbers]. VDI-Zeitschrift (in German). 98: 267–274. Paulin, Eugen (1 September 2007). Logarithmen, Normzahlen, Dezibel, Neper, Phon - natürlich verwandt! [Logarithms, preferred numbers, decibel, neper, phon - naturally related!] (PDF) (in German). Archived (PDF) from the original on 18 December 2016. Retrieved 18 December 2016. == External links == What is a decibel? With sound files and animations Conversion of sound level units: dBSPL or dBA to sound pressure p and sound intensity J OSHA Regulations on Occupational Noise Exposure Working with Decibels (RF signal and field strengths)

The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a power ratio of 101/10 (approximately 1.26) or root-power ratio of 101/20 (approximately 1.12). The unit expresses a relative change or an absolute value. In the latter case, the numeric value expresses the ratio of a value to a fixed reference value; when used in this way, the unit symbol is often suffixed with letter codes that indicate the reference value. For example, for the reference value of 1 volt, a common suffix is "V" (e.g., "20 dBV"). Two principal types of scaling of the decibel are in common use. When expressing a power ratio, it is defined as ten times the logarithm with base 10. That is, a change in power by a factor of 10 corresponds to a 10 dB change in level. When expressing root-power quantities, a change in amplitude by a factor of 10 corresponds to a 20 dB change in level. The decibel scales differ by a factor of two, so that the related power and root-power levels change by the same value in linear systems, where power is proportional to the square of amplitude. The definition of the decibel originated in the measurement of transmission loss and power in telephony of the early 20th century in the Bell System in the United States. The bel was named in honor of Alexander Graham Bell, but the bel is seldom used. Instead, the decibel is used for a wide variety of measurements in science and engineering, most prominently for sound power in acoustics, in electronics and control theory. In electronics, the gains of amplifiers, attenuation of signals, and signal-to-noise ratios are often expressed in decibels.

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Here (2003 film) (wikipedia)

Here (Croatian: Tu) is a 2003 Croatian film directed by Zrinko Ogresta. The film was first released at the Pula Film Festival on 21 July 2003, where it won the Big Golden Arena for Best Film and Zlatko Crnković received the Golden Arena for Best Actor. In July 2004, it was nominated for the Crystal Globe and won the Special Jury Prize at the 39th Karlovy Vary International Film Festival. It also won the Best Feature Film at the Milan Film Festival, the Krzysztof Kieslowski Award at the Denver International Film Festival, and the Critics Award at the Montpellier Mediterranean Film Festival. == Cast == Jasmin Telalović - Kavi Marija Tadić - Duda Zlatko Crnković - Josip Ivo Gregurević - Boris Ivan Herceg - Karlo Nikola Ivosević - Lala Miraj Grbić - Žutan == References == == External links == Here at IMDb

Here (Croatian: Tu) is a 2003 Croatian film directed by Zrinko Ogresta. The film was first released at the Pula Film Festival on 21 July 2003, where it won the Big Golden Arena for Best Film and Zlatko Crnković received the Golden Arena for Best Actor. In July 2004, it was nominated for the Crystal Globe and won the Special Jury Prize at the 39th Karlovy Vary International Film Festival. It also won the Best Feature Film at the Milan Film Festival, the Krzysztof Kieslowski Award at the Denver International Film Festival, and the Critics Award at the Montpellier Mediterranean Film Festival.

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Monguor people (wikipedia)

The Monguor (Monguor language: Mongghul), the Tu people (Chinese: 土族), the White Mongol or the Tsagaan Mongol, are Mongolic people and one of the 56 officially recognized ethnic groups in China. The "Tu" ethnic category was created in the 1950s. According to the 2000 census, the total population was 241,198, who mostly lived in the Qinghai and the Gansu provinces. The 2010 census gave their number as 289,565. The Monguor people speak the Monguor language, which belongs to the family of Mongolic languages but has been heavily influenced by both the local Chinese and Tibetan dialects. Today, nearly all Tu people also speak Chinese. Most are farmers and some keep livestock. Their culture and the social organizations have been influenced by Tibetan Buddhism, Confucianism, Taoism and local beliefs. A few Tu in Huzhu and Minhe are Christian, the result of on-going American and Korean missionary work in the area. == Ethnic origins == The ethnic history of the Monguor is contested. It has been variously suggested that their origins are related to the Tuyuhun Xianbei, to Mongol troops who came to the current Qinghai-Gansu area during the time of the Mongol conquests, to the Shatuo and/or to the Han Chinese. === Terminology === ==== Origins ==== Some references argue that the Chinese term "Tu" was derived from the name of Tuyühu Khan, who was the older son of the King of Murong Xianbei who migrated westward from the northeast in 284. The last character of Tuyühu, pronounced as "hun" today, may have been pronounced "hu" in some dialect of ancient Chinese language. The contemporary reference of this name is rendered "Tuyuhun" in China and the West should be "Tuyühu." It came from the Chinese phonetic transcription of his original name "Teihu", which is still a common name seen among the Monguor today. Since the Chinese language cannot represent "Tei," two characters of "Tu" and "yü" were used. The ethnonym "Tu" in Chinese came from the abbreviation of "the Tuyühu people" or "the people of the Tuyühu Empire." Between the years 908 and 1042, the reference became simplified into "Tuhu" and "Tüihu" people. As the other ethnic groups of the Tuyühu Empire came to be ascribed with different ethnonyms through subsequent history, the Xianbei who founded the empire remained to bear with the identity of "Tu." The name "Tu" was most likely associated with a derogatory meaning and "indigenous people". Its derogatory undertone came from the concurrent meaning of the Chinese character "Tu" for "soil." The ethnonym "Tu" is increasingly a self-reference. ==== Monguor ==== The reference of "Monguor" in the Western publications came from their self-reference as "Chaghan Monguor" (or "White Mongols"). It was derived from their origins from the Murong Xianbei, from whom Tuyühu Khan separated and who had been historically referred to as "the White Section" or "Bai Bu," due to their lighter skin. The term "Monguor" was first used by the European Catholic missionaries, Smedt and Mosaert, who studied the Monguor language and compiled a Monguor-French dictionary in the beginning of the twentieth century. Subsequently, the Flemish Catholic missionary, Louis Schram, made it into an international name through three volumes of extensive reports based on his experiences from having lived among them from 1911 to 1922. The term is a variant pronunciation of "Mongol" in the Monguor language, characterized by the final "-r" in place of "-l" in the Mongolian language. Despite that "Monguor" was made into an international name for the "Tu," it is not representative: the reference is only used by the Monguor in Huzhu and Datong counties in Qinghai, and when used, it should be combined with "Chaghan" (or "White") in order to be distinguished from the "Khara" (or "Black") Mongols. In Minhe County, which holds the most densely populated "Monguor" settlement and where everyone speaks their native "Monguor" language, it is never used as an autonym. == Genetic studies == Sequences in the DNA of the Tu people indicate that Greeks mixed with an East Asian population around 1200 AD, contributing about 7,7% to the Tu genepool. The source of this European DNA might have been merchants travelling the Silk Road. This admixture may come from an earlier period as many of their carnival-like festivals and masked fertility rituals have similarities in the Hellenistic times with Dionysian representations, not in Byzantine Christian-era Greek celebrations. Distribution of Y-chromosome haplogroups in Monguor: O=38.85(O2=31.42,O1a=4.13,O1b=3.3) D=14.87 R1=14.05(R1a=13.22,R1b=0.83) N=11.57 C=9.09 J=5.79 others=5.78 == History == === Donghu === Their earliest origins from the Donghu are reflected in their account of the unique wedding ceremony attributed to Madam Lushi, who organized an ambush through an elaborate banquet combined with liquor and singing in order to subdue a bully named "Wang Mang". In historical terms, the "Wang Mang" people were recorded more than four thousand years ago as physically robust and active on the west of the present Liaoning, whose culture was associated with the Hongshan Culture. In archaeological terms, the Hongshan Culture gradually gave rise to the Lower Xiajiadian Culture and represented the transition toward the bronze technology. It eventually evolved into the Upper Xiajidian Culture, which was associated with the Donghu and characterized by the practice of agriculture and animal husbandry supplemented by handicrafts and bronze art. The Donghu was a federation formed from the Donghu, Wuhuan, and Xianbei. Among the northern ethnic groups, the Donghu was the earliest to evolve into a state of civilization and first developed bronze technology. Through the usage of bronze weaponry and armored cavalry in warfare, they maintained extensive dominance over the Xiongnu on their west. In the end of the third century B.C., the Xiongnu Maodun attacked to destroy the Donghu by surprise and caused disintegration in the federation. The Wuhuan moved to Mt. Wuhuan and engaged in continuous warfare with the Xiongnu on the west and China on the south. The Donghu spoke Mongolic language and was formed by the federation of the Donghu, Wuhuan, and Xianbei. === Xianbei === As the Wuhuan and Xiongnu came to be worn out from the lengthy battles, the Xianbei preserved their strengths by moving northward to Mt. Xianbei. In the first century, the Xianbei defeated the Wuhuan and northern Xiongnu, and developed into a powerful state under the leadership of their elected Khan, Tanshihuai. In the third century, the Eastern Han dynasty (25–220 BC) disintegrated into three kingdoms, including the Cao Wei (220–265) in the north, the Eastern Wu (222–280) in the south, and the Shu Han (221–263) in the southwest. In 235, the Cao Wei assassinated the last Khan of the Xianbei, Kebineng, and caused disintegration in the Xianbei Kingdom. Thereafter, the Xianbei pushed their way inside the Great Wall of China and established extensive presence in China. During the Sixteen Kingdoms (304–439) period, the Xianbei founded six kingdoms: the Former Yan (281–370), Western Yan (384–394), Later Yan (383–407), Southern Yan (398–410), Western Qin (385–430) and Southern Liang (397–414). Most of them were unified by the Tuoba Xianbei, who established the Northern Wei (386–535), which was the first of the Northern dynasties (386–581) founded by the Xianbei. In 534, the Northern Wei split into an Eastern Wei (534–550) and a Western Wei (535–556). The former evolved into the Northern Qi (550–577), and the latter into the Northern Zhou (557–581), while the Southern dynasties were pushed to the south of the Yangtze. In 581, the prime minister of Northern Zhou, Yang Jian, usurped the throne and founded the Sui dynasty (581–618) as Emperor Wen of Sui. His son, Emperor Yang of Sui, annihilated the Chen dynasty (557–589) and unified northern and southern China, thereby bringing an end to the Northern and Southern dynasties era. Over the course of this period, the Xianbei who entered into China were immersed among the Chinese and later classified into "Han". Yet, not all branches of the Xianbei shared this fate. In the 3rd and 4th centuries, Tuyühu, a branch of the Murong Xianbei, undertook a westward migration that allowed them and those who followed them to develop in a different path. === Westward migration === The separation of Tuyühu from the Murong Xianbei occurred during the Western Jin dynasty (265–316), which succeeded the Cao Wei (220–265) in northern China. Legends accounted the separation to be due to a fight between his horses and those of his younger brother, Murong Wei. The actual cause was intense struggle over the Khanate position and disagreement over their future directions. The fraction that supported Murong Wei into the Khanate position aimed at ruling over China, whereas Tuyühu intended to preserve the Xianbei culture and lifestyles. The disagreement resulted in Tuyühu to proclaim as the Khan, or Kehan, and undertook the long westward journey under the title of the Prince of Jin, or Jin Wang, followed by other Xianbei and Wuhuan groups. While passing through western Liaoning and Mt. Bai, more Xianbei groups joined them from the Duan, Yuwen, and Bai sections. At the Hetao Plains near Ordos in Inner Mongolia, Tuyühu Khan led them to reside by Mt. Yin for over thirty years, as the Tuoba Xianbei and Northern Xianbei joined them through political and marriage alliances. After settling down in the northwest, they established the powerful Tuyühu Empire named to his honor as the first Khan who led them there, by subjugating the native peoples who were summarily referred to as the "Qiang" and included more than 100 different and loosely coordinated tribes that did not submit to each other or any authorities. After Tuyühu Khan departed from the northeast, Murong Wei composed an "Older Brother’s Song," or "the Song of A Gan:" "A Gan" is Chinese transcription of "a ga" for "older brother" in the Xianbei language. The song lamented his sadness and longing for Tuyühu. Legends accounted that Murong Wei often sang it until he died and the song got spread into central and northwest China. The Murong Xianbei whom he had led successively founded the Former Yan (281–370), Western Yan (384–394), Later Yan (383–407), and Southern Yan (398–410). Their territories encompassed, at their height, the present Liaoning, Inner Mongolia, Shandong, Shanxi, Hebei, and Henan, and their capitals included Beijing and other cities. Through these establishments, they were immersed among the Chinese, whereas the Xianbei who followed Tuyühu Khan preserved their language and culture. ==== Mt. Xianbei ==== In the extensive migrations that the Xianbei undertook in the northeast, northern, and northwest China, the name of Mt. Xianbei was found along their trajectories. The earliest recorded Mt. Xianbei was in the southern portions of Daxinganling, located in northeast Inner Mongolia, which represented the originating place of the Xianbei. Two Mt. Xianbei were recorded subsequently in western Liaoning: one in the present Jinzhou City and one near Yi County. Another Mt. Xianbei was recorded in the northern portions of Daxinganling, located near Alihe Town of Oroqin Autonomous Banner in Hulunbeiermeng in the northeastern portion of Inner Mongolia that borders eastern Russia. The Gaxian Cave, currently Khabarovsk and Amur regions in the Russian Far East, which had stone inscriptions of the Northern Wei emperor dated 443, was recognized to be the sacred ancestral shrine of the Xianbei. In the northwest, the Qilian Mountains that run along Gansu and Qinghai provinces were referred to as the Greater Mt. Xianbei. In Sanchuan/Guanting of Minhe County in Qinghai, which holds the most densely populated Monguor settlement, Mt. Xianbei stands in the west, upon which sits the ancestral shrine of the Xianbei Khans. === Tuyuhun Empire === After Tuyühu Khan died in Linxia, also known as Huozhou, Gansu in 317, his sixty sons inherited to further develop the empire, by annihilating the Western Qin (385–430), which had annexed Southern Liang (396–414) earlier, and Haolian Xia (407–431) kingdoms, from which the Qinghai Xianbei, Tufa Xianbei, Qifu Xianbei and Haolian Xianbei joined them. These Xianbei groups formed the core of the Tuyuhun Empire and numbered about 3.3 million at their peak. They carried out extensive military expeditions westward, reaching as far as Hetian in Xinjiang and the borders of Kashmir and Afghanistan, and established a vast empire that encompassed Qinghai, Gansu, Ningxia, northern Sichuan, eastern Shaanxi, southern Xinjiang, and most of Tibet, stretching 1,500 kilometers from the east to the west and 1,000 kilometers from the north to the south. They unified northwest China for the first time in history, developed the southern route of the Silk Road, and promoted cultural exchanges between the eastern and western territories, dominating the northwest for more than three and half centuries until the empire was destroyed by the Tibetans who rose up in 670. ==== Tibet ==== The Xianbei asserted cultural imprint in the region. The English reference for "Tibet" may have come from the Xianbei language for Tibetans "Tiebie," in contrast to the self-reference of the Tibetans as "Bo". The name "Tiebie" may have come from the Tuoba Xianbei who founded the Southern Liang (397–414). The Tuoba established the Northern Wei (386–535) and objected to the Tuoba of Southern Liang using the Chinese characters for "Tufa." They shared Tuoba descent. After the Southern Liang were annexed by the Western Qin, and then annexed by the Tuyühu Empire, the majority of Tufa Xianbei joined the Tuyühu Empire. Some submitted under the Northern Wei in China, while a small fraction went into Tibet and gave rise to the name "Tiebie". In the ancient Chinese records, the reference of Tibet included "Tubo" and "Tufan," which reflected the Chinese transcriptions of "Tuoba" and "Tufa." It is likely that "Tuoba" recorded in the Chinese language may have been pronounced as "Tiebie" originally in the Xianbei language. Among the Monguor settlement in Minhe, Qinghai today, the La and Bao Family Villages were accounted to have descended from "Tiebie", indicating that they have derived their origins from the Tufa (Tuoba) Xianbei of the Southern Liang. The Tibetans refer to the Monguor as "Huo’er," which came from the final word of the name of Tuyühu Khan. The Monguor refer to Tuyühu Khan as "Huozhou didi;" in which "Huozhou" was applied to Linxia, Gansu where Tuyühu Khan died, and "didi" was traditionally a reverence term for a deceased ancestor with deity status. The earliest record of the Monguor in the Western publications was made by the French missionaries, Huc and Gabet, who traveled through northwest China in 1844–46. They used "Dschiahour" to represent the Monguor, based on Tibetan reference, in which "Dschia" was likely abbreviated from the first part of "Chaghan" (or "White") from the self-reference of the Monguor as "Chaghan Monguor" (or "White Mongols"), and "Hour" was a variant record to the Tibetan reference of the Monguor as "Huo’er" used by the Tibetans today. === Rise of Tibet === In the beginning of the Tang dynasty, the Tuyühu Empire came to a gradual decline and was increasingly caught in the conflict between the Tang and the Tibetan Empire. Because the Tuyühu Empire controlled the crucial trade routes between the east and the west, the Empire became the immediate target of invasion by the Tang. Meanwhile, the Tibetan Empire developed rapidly under the leadership of Songtsen Gampo, who united the Tibetans and expanded northward, directly threatening the Tuyühu Empire. The exile Tuyühu Khan, Dayan, submitted under Tibet, which resorted to an excuse that Tuyühu objected its marriage with the Tang and sent 200,000 troops to attack. The Tuyühu troops retreated to Qinghai, whereas Tibet went eastward to attack the Tangut and reached into southern Gansu. The Tang government was shocked and sent (five ???) troops to fight. Although Tibet withdrew in response, the Tuyühu Empire lost much of its territory in southern Gansu. Meanwhile, the Tuyühu government was split between the pro-Tang and pro-Tibet factions, with the latter becoming increasingly stronger and corroborating with Tibet to bring about an invasion. The Tang sent its famous general, Xue Rengui, to lead 100,000 troops to fight Tibet in Dafeichuan (present Gonghe County in Qinghai). They were annihilated in an ambush by 200,000 troops of Dayan and Tibet, which became the biggest debacle in the Tang history, and formally brought the Tuyühu Empire to an end. After its fall in 670, the Tuyühu Empire split into an Eastern and Western Kingdom. The Eastern Kingdom existed on the eastern side of the Qilian Mountains and increasingly migrated eastward into central China, whereas the Western Kingdom existed under the leadership of the former exile Khan, Dayan, in Tibet. As the An Lushan Rebellion shook up the Tang court and caused its emperor to flee, Tibet overtook the entire territory of Tuyühu until internal turmoil developed within the Tibetan government and massive revolts brought an end to its rule. Through this period, the Xianbei underwent massive diasporas over a vast territory that stretched from the northwest into central and eastern parts of China, with the greatest concentrations found by Mt. Yin near Ordos. In 946, the Shatuo Turk, Liu Zhiyuan, conspired to murder the highest Xianbei leader, Bai Chengfu, who was reportedly so wealthy that "his horses had silver mangers". With that stolen wealth, which included an abundance of property and thousands of fine horses, Liu established the Later Han (947–950), the shortest dynasty in Chinese history, lasting only four years. The incident took away the central leadership and removed any possibility for the Xianbei to restore the Tuyühu Empire. === Western Xia Empire === The Western Xia Empire inherited the political and social structures of the Tang and further developed an outstanding civilization characterized as "shining and sparkling". It became the new kingdom for the descendants of the Tuyühu Xianbei who had lost their country. The Western Xia made significant achievements in literature, art, music, architecture, and chemistry. Through effective military organizations that integrated cavalry, chariots, archery, shields, artillery (cannons carried on the back of camels), and amphibious troops for combats on the land and water, the Xia army maintained a powerful stance in opposition to the Song, Liao (916–1125), and Jin (1115–1234) empires to its east, the last of which was founded by the Jurchens, who were the predecessors of the Manchus who would found the Qing dynasty (1644–1912). The Xia territory encompassed the present Ningxia, Gansu, eastern Qinghai, northern Shaanxi, northeastern Xinjiang, southwest Inner Mongolia, and southernmost Outer Mongolia, spanning about 800,000 square kilometers. In the beginning of the thirteenth century, Genghis Khan unified the northern grasslands of Mongolia and led the Mongol troops to carry out six rounds of attacks against Western Xia over a period of twenty-two years. As Western Xia resisted vehemently, more and more of its people crossed the Qilian Mountains to join the earlier establishments in Qinghai and Gansu in order to avoid the Mongol assaults, which gave rise to the current settlements of the Monguor. During the last round of attacks, Genghis Khan died in Western Xia. The official Mongol historical account attributed his death to an illness, whereas legends told that he died from a wound inflicted in the battles. After the Xia capital was overrun in 1227, the Mongols destroyed much of hu its architecture and written records, killing the last emperor and massacring tens of thousands of civilians. The Xia troops were later incorporated into the Mongol army in their subsequent military conquests in central and southern China. Due to the fierce resistance of the Xia against the Mongol attacks, especially in causing the death of Genghis, they were initially suppressed in the Yuan dynasty (1271–1368). Toward the middle and later stages of the Yuan, the Xia received equivalent treatment to the ruling Mongols and attained the highest offices in the Central Court. After the Yuan fell, the Xia who followed the Mongols into the northern grassland were immersed among and later classified into the "Mongols." ==== Tangut-Xixia ==== The English reference of "Tangut-Xixia" was derived from the combination of the Mongolian reference of "Tangut" and the Chinese reference as "Xixia" or "Western Xia." The Chinese reference was derived from the location of the empire on the western side of the Yellow River, in contrast to the Liao (916–1125) and Jin on its east. The Mongolian usage of "Tangut" most likely referred to the "Donghu people;" "-t" in Mongolian language means "people". Whereas "Donghu" was a Chinese transcription, its Mongolian reference was "Tünghu". By the time that the Mongols emerged in the thirteenth century, the only "Donghu people" who existed were the "Tu" in Western Xia. That the Mongols referred to Western Xia as "Tangut" to represent the founding ethnic group, the Tuyühu Xianbei, is consistent with the theories of the Mongol origins postulated by the Outer Mongolian scholars, who have held that the Mongols had descended from the Xiongnu, more specifically the eastern Xiongnu who spoke proto-Mongolic language, as opposed to the western Xiongnu who spoke proto-Turkish language. In contrast, the Chinese scholars have characterized that the Mongols had descended from the Xianbei. The Mongols were recorded as "Mengwu Shiwei" in the Northern dynasties: "Mengwu" was a variant Chinese transcription of "Menggu" designated to the Mongols, and "Shiwei" was a variant transcription of the Xianbei, as "Xianbei" was also recorded as "Sian-pie," "Serbi," "Sirbi" and "Sirvi". This equated the Mongols to be "Mongol Xianbei," which was likely associated with the submission of the Xiongnu under Xianbei. In 87 A.D., the Xianbei defeated the northern Xiongnu and killed their king, Chanyu Youliu, causing its thorough disintegration. Thereafter, the Xiongnu submitted under and self-proclaimed to be Xianbei. This resulted in a mix of the Xiongnu into Xianbei and made it difficult to differentiate the two groups in subsequent historical records. That the Mongolian term "Tangut" represented "the Donghu people," the Xianbei and their descendants who had founded the Tuyühu and Western Xia empires, would validate the theories of the Outer Mongolian scholars that the Mongols had descended from the Xiongnu. The fact that there were Wuhuan groups, who were part of the Donghu federation and followed Tuyühu Khan in the westward migration, would make the interpretation that "Tangut" represented "the Donghu people" stronger, not only from reflecting that the Wuhuan joined the Xianbei in the Tuyühu and Western Xia empires, but also contrasting that the Mongols had descended from the Xiongnu. If the Mongols had descended from the Xianbei, as the Chinese scholars characterized, the Mongols would have shared the same ethnic origins with the Xianbei of the Tuyühu Empire and not have called them as "the Donghu people" in reference of Western Xia. While the intimate associations between the two groups were manifested in the cross references of the Mongols as "Mengwu Shiwei" (or "Mongol Xianbei") from the first century and the Monguor as "Chaghan (or White) Monguor" in the thirteenth century, ethnically and culturally they remained different. As much as the prefix "Mengwu" (or "Mongol") in front of "Shiwei" (or "Xianbei") marked the difference between the Mongols and the Xianbei, the prefix "Chaghan" in front of "Monguor" indicated that the Monguor and their Xianbei predecessors were not the same as the Mongols. Culturally, the Mongols have retained a nomadic lifestyle, whereas the social organizations and religious lives of the Monguor are of far greater complexities. ==== Mongols, Khitans, and Jurchens ==== When the Mongols emerged as a mighty power in the thirteenth century, a reverse occurred in the ethnonyms of the Xianbei and Mongols. This was represented in the reference of the Xianbei descendants as "Chaghan Monguor" (or "White Mongols"), which gave rise to the ethnonym of "Monguor" known in the Western publications. The term "White Mongols," or "Bai Menggu," first occurred when Genghis Khan united the Mongols to rise up in Mongolia in 1206. The Xianbei descendants who resided near Mt. Yin self-proclaimed to be "White Mongols" and joined them. They received the same treatment as the Mongols and partook in their westward conquests in Central Asia and Europe. As waves and waves of the Xianbei went south and westward to establish different empires, those who remained in the northeast emerged as major powers later to rule over China. While the "Mongol Xianbei" (or "Mengwu Shiwei") emerged from the northern Manchuria and northeastern Mongolia, the Khitans, or "Qidan" in Chinese, derived their ancestral origins from the Yuwen Xianbei in southern Mongolia, who had earlier founded the Western Wei (535–556) and Northern Zhou (557–581) of the Northern dynasties. When the Khitans established the Liao dynasty (916–1125) in China proper, they were referred to as "Qara (or Black) Khitāy". Their rule gave rise to the reference of China known as "Hătāi" and "Cathay" in the Persian and European countries. The reference of "Qara" (or "Black") as a prefix in the name of the Khitans and "Khara" (or "Black") in that of the Mongols may indicate that both groups had substantial input from the Xiongnu, who by self proclaiming to be "Xianbei" earlier made it hard in distinguish in the Chinese records. After the Xianbei vacated from the northeast, the Jurchens, known as "Nüzhen" in Chinese, moved southward into Manchuria from their original habitation in the Tungus Plains in eastern Russia located on the north of Manchuria. They occupied the former areas of the Xianbei and ascribed Mt. Xianbei with a new name, known as "Daxinganling," which remains to be used today and literally meant "White Mountains" in their Tungus language. They first established the Jin dynasty (1115–1234) in northern China by pushing the Liao Empire of the Khitans westward into Xinjiang. After the Jin Empire was destroyed by the Mongols in 1234, they withdrew back to Manchuria and returned later with the rejoined forces from the Mongols to establish the last dynasty of the Qing (1644–1912) in China under the new ethnonym of Manchu, or "Man Zu" in Chinese. ==== Xia title ==== The full national title of Western Xia was "the Great Xia Kingdom of the White and Mighty," or "Bai Gao Da Xia Guo" (白高大夏国). The term "White" (or "Bai") was designated to the founding ethnic group, the Xianbei descendants of the Tuyühu Empire, which is consistent with their reference of "Chaghan" (or "White"), derived from their origins from the Murong Xianbei known as the "White Section." The term "Mighty" (or "Gao") was designated to the "Qiang" people who formed the majority of the population. The "Qiang" were the native peoples who were subjugated by the Xianbei in the northwest. They initially rebelled but later their fate became intimately associated with the Xianbei, as they actively defended the empire when the enemies attacked. In addition to the Tibetans and authentic Han people, the "Qiang" comprised a portion of the Miao/Hmong who were relocated to the northwest from central China after their Three Miao Kingdom was destroyed by the legendary Chinese Emperor Yü the Great about four thousand years ago. The "Qiang" referred to Western Xia as their "Gao (or ‘Mighty’) Mi Yao" Kingdom. When "Mi Yao" is pronounced together, it is similar to "Miao." Since the autonyms of the Miao/Hmong include "Guoxiong", "Gaoxiong," and "Gouxiong," the character "Gao" (or "Mighty") in the Xia national title could have derived as a variant abbreviation. "Bai Gao" in the national title was in turn used it to refer to the Yellow River, which had traditionally been referred to as the "Mother River" of China, known as "Mu Qin He," that has nurtured their homeland. === Current status === The Flemish Catholic missionary, Schram, who wrote about the Monguor based on residence in the current Qinghai Province in the early twentieth century, cited Comte de Lesdain, who characterized the Monguor as "the most authentic reminder of the primitive race from which the Chinese sprung." This characterization reflected that the Monguor culture under their observation has embodied "a high civilization fortified by its own history and distinctive social structure" developed by the Xianbei forefathers from their extensive rulings over China and preserved by the "Monguor"/"Tu". As early as the Tuyühu period, Confucianism served as the core ideology to govern the country, and the Chinese Buddhism and Shamanism functioned as the principle religions. In Western Xia, Confucianism was further strengthened, and Taoism was made into the national religion along with Buddhism. As the Yellow Sect of Buddhism, also known as the Tibetan Buddhism, became prevalent in the northwest, their religious lives shifted from the Chinese toward Tibetan Buddhism. After Western Xia fell, its territory centered in Ningxia was fragmented by the successive establishments of Shaanxi, Gansu, and Qinghai provinces, which increasingly weakened the political and military powers of the Monguor. Through the Ming (1368–1644) and Qing (1644–1912) dynasties, the Monguor continued to play important roles in the national defense, and political and religious affairs of China. Starting in the middle of the Ming dynasty, the ranches of the Monguor were taken into the state possession, and their horses became the subject of being drafted into the national army and looted by the Mongols from the north, resulting in the eventual shift of their lifestyles toward sedentary agriculture, supplemented by minimum animal husbandry, as the original Monguor groups became settled into the form of different villages. In the last two centuries, the areas formerly occupied by the Monguor were encroached upon by increasing inland Chinese migrations. Throughout this period, the Monguor maintained a high degree of political autonomy and self governance under the local chiefdom system of Tusi. The Monguor troops led by their Tusi defended not only their own homeland but also joined the national army to participate in wars that took place as far as in eastern Liaoning, Shaanxi, Shanxi, Yunnan, Mongolia, and Dunhuang, which progressively weakened their military power. Their political power came to the ultimate decline when the Tusi system was abolished in 1931, which exacerbated more Monguor to lose their language. By the founding of the People's Republic of China in 1949, only about fifty thousand of the Monguor have maintained to speak their language, primarily in Qinghai and Gansu. During the Chinese classificatory campaigns carried out in the 1950s, those who could no longer speak their language were classified into "Han", those who could not speak their language but adopted the Islamic religion were classified into "Hui", those who followed the Mongols into the northern grassland were classified into "Mongols", and those who spoke their language and adopted the Islamic religion were classified into "Dongxiang", "Bonan" and "Yugur", the last of which represented the intermixture of the Xianbei and Sari Uyghurs. == Culture == Most Monguor in rapidly changing rural settlements today practice sedentary agriculture, supplemented by minimum animal husbandry, and seasonal work in towns and cities. Those who have succeeded in the Chinese educational system take up government jobs in a wide range of academic, medical, and business fields. Traditional Monguor culture and language have become endangered. Traditional events like weddings, Nadun, funerals, and New Year rituals are increasingly abbreviated and traditional songs, riddles, folktales, and proverbs are vanishing. === Religion === In most villages, a Buddhist temple and a Taoist shrine coexist. Almost all the temples and shrines seen today have been rebuilt in the last three decades, since they were invariably destroyed during the Cultural Revolution (1966–1976). While Buddhist monks are common in most villages, Taoist priests and shamans have become very few and serve the whole area. The Taoist priests take charge of diverse functions that include weddings, funerals, and looking after the shrines, whereas the shaman's primary function is to serve as a trance medium during the Nadun celebration and sometimes illness management. Local accounts indicated that there have been multiple Catholic churches constructed in the Monguor areas in the past. They were destroyed in the early 1950s after the Communists took control and have not been rebuilt. === Nadun and Anzhao === Distinctive cultural events take place throughout the year. Whereas the common festival held during the Spring Festival is "Yangguo," the most characteristic tradition is represented by Nadun that takes place in the end of the summer. Nadun resembles Nadam of the Mongols in name but are different in format and content. Both "Nadun" and "Nadam" are special nouns designated to an annual festival and reflect their shared origins from the Xianbei who were recorded to have "one major gathering every spring for leisure and fun by river". Whereas the Mongolian Nadam preserved the nomadic features of horse race, wrestling, and archery, the Monguor Nadun has encoded their history through masked dance performances and presents as an annual military drill combined with joyful celebrations of harvest. Held by villages in turn along the Yellow River and circles through the entire Sanchuan/Guanting region in Minhe, the Nadun festival is inherently tied to agricultural work. It functions as the Monguor form of "Thanksgiving" in the Western culture and expresses gratitude for an abundance of harvest blessed by Heaven referred to as "Tiangere." The event lasts over two months, starting from the twelfth of the seventh month to the fifteenth of the ninth month by the Chinese lunar calendar, and spans for a total of 63 days, giving rise to its eponym as "the world’s longest festival". Among the Huzhu Monguor, the characteristic traditional dance is "Anzhao." Its name and styles bear resemblance to the "Andai" dance of the Mongols who live in Ordos, an area that has historically served as the transitional point for the Xianbei to move about in China. === Wedding songs === The traditional weddings of the Monguor differ markedly. In Minhe County, elaborate rules of courtesy and appropriateness were at work. Many songs "daola" were sung for days and nights with great variations in melody and contents. Wherever the Monguor go, they take their songs with them, which can be heard in parties, banquets, and at gatherings in cities where they work. == References == == Further reading == == External links == The Tu ethnic minority (Chinese government site in English) Tu entry on Ethnologue, version 15 Mongour wedding Traditions Case Studies: Monguor Data Collection Salar and Monguor grammatical sketches; pictures and sound samples Several Monguor folktales (Archived version)

The Monguor (Monguor language: Mongghul), the Tu people (Chinese: 土族), the White Mongol or the Tsagaan Mongol, are Mongolic people and one of the 56 officially recognized ethnic groups in China. The "Tu" ethnic category was created in the 1950s. According to the 2000 census, the total population was 241,198, who mostly lived in the Qinghai and the Gansu provinces. The 2010 census gave their number as 289,565. The Monguor people speak the Monguor language, which belongs to the family of Mongolic languages but has been heavily influenced by both the local Chinese and Tibetan dialects. Today, nearly all Tu people also speak Chinese. Most are farmers and some keep livestock. Their culture and the social organizations have been influenced by Tibetan Buddhism, Confucianism, Taoism and local beliefs. A few Tu in Huzhu and Minhe are Christian, the result of on-going American and Korean missionary work in the area.

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tu

TU (wikipedia)

Tu or TU may refer to: == Language == Tu language Tu (cuneiform), a cuneiform sign tu or tú the 2nd-person singular subject pronoun in many languages; see personal pronoun T–V distinction (from the Latin pronouns tu and vos), the use in some languages, of a different personal pronoun for formality or social distance Tsu (kana), also romanized as tu == People and names == Tū (Tūmatauenga), a supernatural being in Māori mythology Tu people, the Monguor people of the People's Republic of China Tu language Tu Holloway (born 1989), basketball player for Maccabi Rishon LeZion in the Israeli Basketball Premier League Tu (surname) 屠, a rare Chinese family name Du (surname) 杜 or Tu, a common Chinese family name == Music == Tú (Canadian band), a Canadian pop music duo in the late-1980s Tu (American band), an American duo, formed by member of King Crimson === Songs === "Tu" (Umberto Tozzi song), 1978 "Tu", a song by Umberto Bindi, 1959 "Tu", a song by Ewa Farna, 2015 == Other == Tu (film) Here (2003 film) or Tu, a Croatian film Tu, a brand of clothing from Sainsbury's Tu (cake), a type of Tibetan cake == Acronyms == === Companies and organizations === TU (union), the international union for T-Mobile workers TU Media, a Digital Multimedia Broadcasting mobile companies in Korea Toimihenkilöunioni (Union of Salaried Employees), a Finnish trade union Tunisair (IATA airline code TU) Transunion, a consumer credit reporting agency Tupolev, a Russian aerospace and defence company Teknisk Ukeblad, a Norwegian engineering magazine The Times Union, an Albany newspaper New York City Teachers Union (1916–1964), commonly known as the "TU" Trout Unlimited, conservation group === Units of measurement === TU (time unit), a unit of time equal to 1024 microseconds Transmission unit, a historical unit of loss in long distance telephony Tritium unit, a measure of tritium concentration in water Tuberculin Units, a measure of strength of tuberculin === Universities === ==== In the United States ==== Taylor University, Indiana Temple University, Pennsylvania Thomas University, Georgia Touro University California, California Touro University Nevada, Nevada Towson University, Maryland Trinity University, Texas Troy University, Alabama Tufts University, Massachusetts Tulane University, Louisiana Tuskegee University, Alabama University of Tulsa, Oklahoma t.u., a derisive reference to the University of Texas at Austin by students and supporters of in-state rival Texas A&M University ==== In other countries ==== University of Tartu (Tartu Ülikool), Estonia Any Technische Universität, i.e. university of technology in German-speaking countries Technische Universiteit Delft, Netherlands Technische Universiteit Eindhoven, Netherlands Tezpur University, Assam, India Thapar University, Patiala, India Thammasat University, Thailand Tianjin University, Tianjin, China Tibet University, Lhasa, Tibet Autonomous Region, China Tooling University, an American non-profit educational technology company Tribhuvan University, Kathmandu, Nepal Technological Universities of Myanmar === Other uses === Tren Urbano, the metro system in San Juan, Puerto Rico Tu Hundred, a district of Vccästmanland in Sweden Universal Time, "Tempus Universalis" Thulium, a chemical element with obsolete symbol Tu Translation unit, a single cognitive unit of text Translation unit (programming), the ultimate input to the compiler == See also == Tú (disambiguation) UT (disambiguation) Tuesday

Tu or TU may refer to:

56

tu

Tsu (kana) (wikipedia)

Tsu (hiragana: つ, katakana: ツ) is one of the Japanese kana, each of which represents one mora. Both are phonemically /tɯ/, reflected in the Nihon-shiki and Kunrei-shiki Romanization tu, although for phonological reasons, the actual pronunciation is [t͡sɯᵝ] , reflected in the Hepburn romanization tsu. The small kana っ/ッ, known as sokuon, are identical but somewhat smaller. They are mainly used to indicate consonant gemination and commonly used at the end of lines of dialogue in fictional works as a symbol for a glottal stop. The dakuten forms づ, ヅ, pronounced the same as the dakuten forms of the su kana in most dialects (see yotsugana), are uncommon. They are primarily used for indicating a voiced consonant in the middle of a compound word (see rendaku), and they can never begin a word. In the Ainu language, it can be written with a handakuten (which can be entered into a computer as either one character (ツ゚) or two combined characters (ツ゜) to represent the sound [tu͍], which is interchangeable with the katakana ト゚. The katakana form has become popular as an emoticon in the Western world due to its resemblance to a smiling face and as part of a "shrug" emoticon, known alternatively as Shruggie, rendered as: ¯\_(ツ)_/¯ . ヅァ, ヅェ and ヅォ are used in gairaigos; these pronunciations are not same as ズァ (zwa), ズェ (zwe) and ズォ (zwo). == Stroke order == == Other communicative representations == Full Braille representation Computer encodings == See also == Sokuon Dakuten and Handakuten Kanji Chōonpu == References ==

Tsu (hiragana: つ, katakana: ツ) is one of the Japanese kana, each of which represents one mora. Both are phonemically /tɯ/, reflected in the Nihon-shiki and Kunrei-shiki Romanization tu, although for phonological reasons, the actual pronunciation is [t͡sɯᵝ] , reflected in the Hepburn romanization tsu. The small kana っ/ッ, known as sokuon, are identical but somewhat smaller. They are mainly used to indicate consonant gemination and commonly used at the end of lines of dialogue in fictional works as a symbol for a glottal stop. The dakuten forms づ, ヅ, pronounced the same as the dakuten forms of the su kana in most dialects (see yotsugana), are uncommon. They are primarily used for indicating a voiced consonant in the middle of a compound word (see rendaku), and they can never begin a word. In the Ainu language, it can be written with a handakuten (which can be entered into a computer as either one character (ツ゚) or two combined characters (ツ゜) to represent the sound [tu͍], which is interchangeable with the katakana ト゚. The katakana form has become popular as an emoticon in the Western world due to its resemblance to a smiling face and as part of a "shrug" emoticon, known alternatively as Shruggie, rendered as: ¯\_(ツ)_/¯ . ヅァ, ヅェ and ヅォ are used in gairaigos; these pronunciations are not same as ズァ (zwa), ズェ (zwe) and ズォ (zwo).

57

tu

Tú (Canadian band) (wikipedia)

Tú was a Canadian pop music duo from the Toronto area in the 1980s, featuring twin sisters Amanda and Cassandra DiBlasi. == History == The DiBlasi twins appeared on The Tommy Hunter Show in 1985. They released a self-titled album in 1987 on RCA Records. Their second album, Secrets in the Dark, was released in 1989 by Columbia Records. Their biggest hit, the single "Stay with Me", was their only Top 10 song, reaching number 8 on the Canadian music charts in 1987. They also released the singles "I Used to Cry", "Language of Love", "Stop Breaking My Heart", and "Le Freak - Tú Freak", a cover version of the 1978 Chic song "Le Freak". Tú also appeared as backup singers in Platinum Blonde's video for "Fire". == References == == External links == Tú fansite

Tú was a Canadian pop music duo from the Toronto area in the 1980s, featuring twin sisters Amanda and Cassandra DiBlasi.

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starbright foundation

Starlight Children's Foundation (wikipedia)

Starlight Children's Foundation is a nonprofit organization founded in 1982. Starlight's programs include providing hospital wear, games, and deliveries to hospitalized children. The programs are provided directly to children through Starlight's network of more than 700 children's hospitals and other community health partners throughout the world. Starlight's US operations are based in Los Angeles, California. Starlight also operates in Canada, the United Kingdom, Australia and possibly other countries, though their websites are unclear about their global operations. == Programs == The non-profit's programs aim to deliver happiness to seriously ill kids and include specially manufactured Starlight Nintendo Gaming Stations for hospital use, Disney Princess-themed hospital wear, and Starlight Radio Flyer Hero Wagons with an IV pole attachment. Real-life superhero Captain Starlight also entertains sick and ill kids in hospitals as well. == History == Starlight Children's Foundation was founded in 1982 by filmmaker Peter Samuelson and actress Emma Samms, who was inspired by her 8-year-old brother's death from aplastic anemia. Steven Spielberg serves as the organization's chairman Emeritus. Starlight's current CEO is Adam Garone. == Starbright World == Starbright World was the first-ever private social network, started in 1995 by filmmaker and chairman Emeritus Steven Spielberg, Peter Samuelson and Norman Schwarzkopf Jr. It served to connect chronically ill teenagers with life-threatening medical conditions, and their siblings, in a safe, online community where they could chat, blog, post content, and meet others who shared similar experiences. Starbright World was taken offline on August 31, 2015. == References == == External links == Official website

Starlight Children's Foundation is a nonprofit organization founded in 1982. Starlight's programs include providing hospital wear, games, and deliveries to hospitalized children. The programs are provided directly to children through Starlight's network of more than 700 children's hospitals and other community health partners throughout the world. Starlight's US operations are based in Los Angeles, California. Starlight also operates in Canada, the United Kingdom, Australia and possibly other countries, though their websites are unclear about their global operations.

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computer

Computer (wiktionary)

Borrowed from English computer. IPA(key): /kɔmˈpjuːtɐ/ Computer m (strong, genitive Computers, plural Computer) computer (programmable electronic device that performs mathematical calculations, logical operations, and usually also data retrieval/storage) Synonym: Rechner PC “Computer” in Duden online “Computer” in Digitales Wörterbuch der deutschen Sprache From English computer, partly through German Computer. IPA(key): /komˈpjuːteʀ/, [komˈpjuːtɐ] Computer m (plural Computeren) computer

60

computer

computer (wiktionary)

From compute +‎ -er. Doublet of cantore, counter, and kontor. Sense 1 first attested in 1613 by the poet Richard Brathwait. Sense 2 first attested in 1897 in the Engineering magazine. (Received Pronunciation) IPA(key): /kəmˈpjuːtə/ (General American) IPA(key): /kəmˈpjutəɹ/, [kəmˈpʰjuɾəɹ] Rhymes: -uːtə(ɹ) Hyphenation: com‧put‧er computer (plural computers) (now rare, chiefly historical) A person employed to perform computations; one who computes. [from 17th c.] Synonyms: computator, mental calculator, human calculator Hyponym: computress (by restriction, chiefly historical) A male computer, where the female computer is called a computress. A programmable electronic device that performs mathematical calculations and logical operations, especially one that can process, store and retrieve large amounts of data very quickly; now especially, a small one for personal or home use employed for manipulating text or graphics, accessing the Internet, or playing games or media. [from 20th c.] Synonyms: processor, (informal) 'puter, (slang) box, machine, calculator; see also Thesaurus:computer Hyponyms: desktop, laptop, portable computer, stored-program computer For quotations using this term, see Citations:computer. (programmable electronic device): electronic device, machine computer (third-person singular simple present computers, present participle computering, simple past and past participle computered) (rare, nonstandard) (intransitive) To use a computer. (transitive) To send via computer. (transitive) To transfer onto a computer; to computerize. Richard Brathwaite, Of the Mortalite of Man, 1613 computer – Oxford English Dictionary, second edition (1989). Category:computer on Wikimedia Commons.Wikimedia Commons Borrowed from English computer. IPA(key): [kʰʌmˈpʰj̊uːd̥ɐ] computer c (singular definite computeren, plural indefinite computere) computer (machine) kompjoeter (eye dialect, humorous) IPA(key): /kɔmˈpjutər/ Hyphenation: com‧pu‧ter Rhymes: -utər Unadapted borrowing from English computer. computer m (plural computers, diminutive computertje n) computer → Trió: konpëjutë See the etymology of the corresponding lemma form. computer inflection of computeren: first-person singular present indicative imperative Borrowed from Latin computāre (“to compute, sum up”). See also the doublets compter and conter. IPA(key): /kɔ̃.py.te/ Homophones: computai, computé, computée, computées, computés, computez computer (archaic, rare) to compute supputer compter “computer”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012. compteur Unadapted borrowing from English computer. IPA(key): /komˈpju.ter/ Rhymes: -uter Hyphenation: com‧pù‧ter computer m (invariable) computer (calculating device) Synonyms: calcolatore, elaboratore computer first-person singular present passive subjunctive of computō Unadapted borrowing from English computer. computer n (plural computere) computer Synonyms: calculator, ordinator computa Borrowed from English computer. computer m (plural computers) computer Synonym: calculater

61

computer

Computer (wikipedia)

A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations (computation). Modern digital electronic computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices such as personal computers and mobile devices such as smartphones. Computers power the Internet, which links billions of computers and users. Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution, some mechanical devices were built to automate long, tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II, both electromechanical and using thermionic valves. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power, and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (Moore's law noted that counts doubled every two years), leading to the Digital Revolution during the late 20th and early 21st centuries. Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, together with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source, and they enable the results of operations to be saved and retrieved. == Etymology == It was not until the mid-20th century that the word acquired its modern definition; according to the Oxford English Dictionary, the first known use of the word computer was in a different sense, in a 1613 book called The Yong Mans Gleanings by the English writer Richard Brathwait: "I haue [sic] read the truest computer of Times, and the best Arithmetician that euer [sic] breathed, and he reduceth thy dayes into a short number." This usage of the term referred to a human computer, a person who carried out calculations or computations. The word continued to have the same meaning until the middle of the 20th century. During the latter part of this period, women were often hired as computers because they could be paid less than their male counterparts. By 1943, most human computers were women. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, meaning 'one who calculates'; this is an "agent noun from compute (v.)". The Online Etymology Dictionary states that the use of the term to mean "'calculating machine' (of any type) is from 1897." The Online Etymology Dictionary indicates that the "modern use" of the term, to mean 'programmable digital electronic computer' dates from "1945 under this name; [in a] theoretical [sense] from 1937, as Turing machine". The name has remained, although modern computers are capable of many higher-level functions. == History == === Pre-20th century === Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was most likely a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, likely livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example. The abacus was initially used for arithmetic tasks. The Roman abacus was developed from devices used in Babylonia as early as 2400 BCE. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money. The Antikythera mechanism is believed to be the earliest known mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to approximately c. 100 BCE. Devices of comparable complexity to the Antikythera mechanism would not reappear until the fourteenth century. Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī in the early 11th century. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BCE and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235. Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels, c. 1000 AD. The sector, a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation. The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage. The slide rule was invented around 1620–1630 by the English clergyman William Oughtred, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Slide rules with special scales are still used for quick performance of routine calculations, such as the E6B circular slide rule used for time and distance calculations on light aircraft. In the 1770s, Pierre Jaquet-Droz, a Swiss watchmaker, built a mechanical doll (automaton) that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically "programmed" to read instructions. Along with two other complex machines, the doll is at the Musée d'Art et d'Histoire of Neuchâtel, Switzerland, and still operates. In 1831–1835, mathematician and engineer Giovanni Plana devised a Perpetual Calendar machine, which, through a system of pulleys and cylinders and over, could predict the perpetual calendar for every year from 0 CE (that is, 1 BCE) to 4000 CE, keeping track of leap years and varying day length. The tide-predicting machine invented by the Scottish scientist Sir William Thomson in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location. The differential analyser, a mechanical analog computer designed to solve differential equations by integration, used wheel-and-disc mechanisms to perform the integration. In 1876, Sir William Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators. In a differential analyzer, the output of one integrator drove the input of the next integrator, or a graphing output. The torque amplifier was the advance that allowed these machines to work. Starting in the 1920s, Vannevar Bush and others developed mechanical differential analyzers. In the 1890s, the Spanish engineer Leonardo Torres Quevedo began to develop a series of advanced analog machines that could solve real and complex roots of polynomials, which were published in 1901 by the Paris Academy of Sciences. === First computer === Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his difference engine he announced his invention in 1822, in a paper to the Royal Astronomical Society, titled "Note on the application of machinery to the computation of astronomical and mathematical tables", he also designed to aid in navigational calculations, in 1833 he realized that a much more general design, an analytical engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete. The machine was about a century ahead of its time. All the parts for his machine had to be made by hand – this was a major problem for a device with thousands of parts. Eventually, the project was dissolved with the decision of the British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to political and financial difficulties as well as his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow. Nevertheless, his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906. === Electromechanical calculating machine === In his work Essays on Automatics published in 1914, Leonardo Torres Quevedo wrote a brief history of Babbage's efforts at constructing a mechanical Difference Engine and Analytical Engine. The paper contains a design of a machine capable to calculate formulas like a x ( y − z ) 2 {\displaystyle a^{x}(y-z)^{2}} , for a sequence of sets of values. The whole machine was to be controlled by a read-only program, which was complete with provisions for conditional branching. He also introduced the idea of floating-point arithmetic. In 1920, to celebrate the 100th anniversary of the invention of the arithmometer, Torres presented in Paris the Electromechanical Arithmometer, which allowed a user to input arithmetic problems through a keyboard, and computed and printed the results, demonstrating the feasibility of an electromechanical analytical engine. === Analog computers === During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers. The first modern analog computer was a tide-predicting machine, invented by Sir William Thomson (later to become Lord Kelvin) in 1872. The differential analyser, a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in 1876 by James Thomson, the elder brother of the more famous Sir William Thomson. The art of mechanical analog computing reached its zenith with the differential analyzer, built by H. L. Hazen and Vannevar Bush at MIT starting in 1927. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. W. Nieman. A dozen of these devices were built before their obsolescence became obvious. By the 1950s, the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remained in use during the 1950s in some specialized applications such as education (slide rule) and aircraft (control systems). === Digital computers === ==== Electromechanical ==== By 1938, the United States Navy had developed an electromechanical analog computer small enough to use aboard a submarine. This was the Torpedo Data Computer, which used trigonometry to solve the problem of firing a torpedo at a moving target. During World War II similar devices were developed in other countries as well. Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2, created by German engineer Konrad Zuse in 1939 in Berlin, was one of the earliest examples of an electromechanical relay computer. In 1941, Zuse followed his earlier machine up with the Z3, the world's first working electromechanical programmable, fully automatic digital computer. The Z3 was built with 2000 relays, implementing a 22 bit word length that operated at a clock frequency of about 5–10 Hz. Program code was supplied on punched film while data could be stored in 64 words of memory or supplied from the keyboard. It was quite similar to modern machines in some respects, pioneering numerous advances such as floating-point numbers. Rather than the harder-to-implement decimal system (used in Charles Babbage's earlier design), using a binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time. The Z3 was not itself a universal computer but could be extended to be Turing complete. Zuse's next computer, the Z4, became the world's first commercial computer; after initial delay due to the Second World War, it was completed in 1950 and delivered to the ETH Zurich. The computer was manufactured by Zuse's own company, Zuse KG, which was founded in 1941 as the first company with the sole purpose of developing computers in Berlin. ==== Vacuum tubes and digital electronic circuits ==== Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers, working at the Post Office Research Station in London in the 1930s, began to explore the possible use of electronics for the telephone exchange. Experimental equipment that he built in 1934 went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. In the US, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed and tested the Atanasoff–Berry Computer (ABC) in 1942, the first "automatic electronic digital computer". This design was also all-electronic and used about 300 vacuum tubes, with capacitors fixed in a mechanically rotating drum for memory. During World War II, the British code-breakers at Bletchley Park achieved a number of successes at breaking encrypted German military communications. The German encryption machine, Enigma, was first attacked with the help of the electro-mechanical bombes which were often run by women. To crack the more sophisticated German Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus. He spent eleven months from early February 1943 designing and building the first Colossus. After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944 and attacked its first message on 5 February. Colossus was the world's first electronic digital programmable computer. It used a large number of valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform a variety of boolean logical operations on its data, but it was not Turing-complete. Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Colossus Mark I contained 1,500 thermionic valves (tubes), but Mark II with 2,400 valves, was both five times faster and simpler to operate than Mark I, greatly speeding the decoding process. The ENIAC (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built in the U.S. Although the ENIAC was similar to the Colossus, it was much faster, more flexible, and it was Turing-complete. Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches. The programmers of the ENIAC were six women, often known collectively as the "ENIAC girls". It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract 5000 times a second, a thousand times faster than any other machine. It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words (about 80 bytes). Built under the direction of John Mauchly and J. Presper Eckert at the University of Pennsylvania, ENIAC's development and construction lasted from 1943 to full operation at the end of 1945. The machine was huge, weighing 30 tons, using 200 kilowatts of electric power and contained over 18,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors. === Modern computers === ==== Concept of modern computer ==== The principle of the modern computer was proposed by Alan Turing in his seminal 1936 paper, On Computable Numbers. Turing proposed a simple device that he called "Universal Computing machine" and that is now known as a universal Turing machine. He proved that such a machine is capable of computing anything that is computable by executing instructions (program) stored on tape, allowing the machine to be programmable. The fundamental concept of Turing's design is the stored program, where all the instructions for computing are stored in memory. Von Neumann acknowledged that the central concept of the modern computer was due to this paper. Turing machines are to this day a central object of study in theory of computation. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete, which is to say, they have algorithm execution capability equivalent to a universal Turing machine. ==== Stored programs ==== Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine. With the proposal of the stored-program computer this changed. A stored-program computer includes by design an instruction set and can store in memory a set of instructions (a program) that details the computation. The theoretical basis for the stored-program computer was laid out by Alan Turing in his 1936 paper. In 1945, Turing joined the National Physical Laboratory and began work on developing an electronic stored-program digital computer. His 1945 report "Proposed Electronic Calculator" was the first specification for such a device. John von Neumann at the University of Pennsylvania also circulated his First Draft of a Report on the EDVAC in 1945. The Manchester Baby was the world's first stored-program computer. It was built at the University of Manchester in England by Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948. It was designed as a testbed for the Williams tube, the first random-access digital storage device. Although the computer was described as "small and primitive" by a 1998 retrospective, it was the first working machine to contain all of the elements essential to a modern electronic computer. As soon as the Baby had demonstrated the feasibility of its design, a project began at the university to develop it into a practically useful computer, the Manchester Mark 1. The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1, the world's first commercially available general-purpose computer. Built by Ferranti, it was delivered to the University of Manchester in February 1951. At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam. In October 1947 the directors of British catering company J. Lyons & Company decided to take an active role in promoting the commercial development of computers. Lyons's LEO I computer, modelled closely on the Cambridge EDSAC of 1949, became operational in April 1951 and ran the world's first routine office computer job. ==== Transistors ==== The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen and Walter Brattain, while working under William Shockley at Bell Labs, built the first working transistor, the point-contact transistor, in 1947, which was followed by Shockley's bipolar junction transistor in 1948. From 1955 onwards, transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space. However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialized applications. At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves. Their first transistorized computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955. However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer. That distinction goes to the Harwell CADET of 1955, built by the electronics division of the Atomic Energy Research Establishment at Harwell. The metal–oxide–silicon field-effect transistor (MOSFET), also known as the MOS transistor, was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959. It was the first truly compact transistor that could be miniaturized and mass-produced for a wide range of uses. With its high scalability, and much lower power consumption and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuits. In addition to data processing, it also enabled the practical use of MOS transistors as memory cell storage elements, leading to the development of MOS semiconductor memory, which replaced earlier magnetic-core memory in computers. The MOSFET led to the microcomputer revolution, and became the driving force behind the computer revolution. The MOSFET is the most widely used transistor in computers, and is the fundamental building block of digital electronics. ==== Integrated circuits ==== The next great advance in computing power came with the advent of the integrated circuit (IC). The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer. Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C., on 7 May 1952. The first working ICs were invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor. Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material ... wherein all the components of the electronic circuit are completely integrated". However, Kilby's invention was a hybrid integrated circuit (hybrid IC), rather than a monolithic integrated circuit (IC) chip. Kilby's IC had external wire connections, which made it difficult to mass-produce. Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. Noyce's invention was the first true monolithic IC chip. His chip solved many practical problems that Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas Kilby's chip was made of germanium. Noyce's monolithic IC was fabricated using the planar process, developed by his colleague Jean Hoerni in early 1959. In turn, the planar process was based on Mohamed M. Atalla's work on semiconductor surface passivation by silicon dioxide in the late 1950s. Modern monolithic ICs are predominantly MOS (metal–oxide–semiconductor) integrated circuits, built from MOSFETs (MOS transistors). The earliest experimental MOS IC to be fabricated was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962. General Microelectronics later introduced the first commercial MOS IC in 1964, developed by Robert Norman. Following the development of the self-aligned gate (silicon-gate) MOS transistor by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967, the first silicon-gate MOS IC with self-aligned gates was developed by Federico Faggin at Fairchild Semiconductor in 1968. The MOSFET has since become the most critical device component in modern ICs. The development of the MOS integrated circuit led to the invention of the microprocessor, and heralded an explosion in the commercial and personal use of computers. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel 4004, designed and realized by Federico Faggin with his silicon-gate MOS IC technology, along with Ted Hoff, Masatoshi Shima and Stanley Mazor at Intel. In the early 1970s, MOS IC technology enabled the integration of more than 10,000 transistors on a single chip. System on a Chip (SoCs) are complete computers on a microchip (or chip) the size of a coin. They may or may not have integrated RAM and flash memory. If not integrated, the RAM is usually placed directly above (known as Package on package) or below (on the opposite side of the circuit board) the SoC, and the flash memory is usually placed right next to the SoC, this all done to improve data transfer speeds, as the data signals do not have to travel long distances. Since ENIAC in 1945, computers have advanced enormously, with modern SoCs (Such as the Snapdragon 865) being the size of a coin while also being hundreds of thousands of times more powerful than ENIAC, integrating billions of transistors, and consuming only a few watts of power. === Mobile computers === The first mobile computers were heavy and ran from mains power. The 50 lb (23 kg) IBM 5100 was an early example. Later portables such as the Osborne 1 and Compaq Portable were considerably lighter but still needed to be plugged in. The first laptops, such as the Grid Compass, removed this requirement by incorporating batteries – and with the continued miniaturization of computing resources and advancements in portable battery life, portable computers grew in popularity in the 2000s. The same developments allowed manufacturers to integrate computing resources into cellular mobile phones by the early 2000s. These smartphones and tablets run on a variety of operating systems and recently became the dominant computing device on the market. These are powered by System on a Chip (SoCs), which are complete computers on a microchip the size of a coin. == Types == Computers can be classified in a number of different ways, including: === By architecture === Analog computer Digital computer Hybrid computer Harvard architecture Von Neumann architecture Complex instruction set computer Reduced instruction set computer === By size, form-factor and purpose === Supercomputer Mainframe computer Minicomputer (term no longer used), Midrange computer Server Rackmount server Blade server Tower server Personal computer Workstation Microcomputer (term no longer used) Home computer (term fallen into disuse) Desktop computer Tower desktop Slimline desktop Multimedia computer (non-linear editing system computers, video editing PCs and the like, this term is no longer used) Gaming computer All-in-one PC Nettop (Small form factor PCs, Mini PCs) Home theater PC Keyboard computer Portable computer Thin client Internet appliance Laptop Desktop replacement computer Gaming laptop Rugged laptop 2-in-1 PC Ultrabook Chromebook Subnotebook Smartbook Netbook Mobile computers: Tablet computer Smartphone Ultra-mobile PC Pocket PC Palmtop PC Handheld PC Pocket computer Wearable computer Smartwatch Smartglasses Single-board computer Plug computer Stick PC Programmable logic controller Computer-on-module System on module System in a package System-on-chip (Also known as an Application Processor or AP if it lacks circuitry such as radio circuitry) Microcontroller == Hardware == The term hardware covers all of those parts of a computer that are tangible physical objects. Circuits, computer chips, graphic cards, sound cards, memory (RAM), motherboard, displays, power supplies, cables, keyboards, printers and "mice" input devices are all hardware. === History of computing hardware === === Other hardware topics === A general-purpose computer has four main components: the arithmetic logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by buses, often made of groups of wires. Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates so that one or more of the circuits may control the state of one or more of the other circuits. === Input devices === When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are: Computer keyboard Digital camera Graphics tablet Image scanner Joystick Microphone Mouse Overlay keyboard Real-time clock Trackball Touchscreen Light pen === Output devices === The means through which computer gives output are known as output devices. Some examples of output devices are: Computer monitor Printer PC speaker Projector Sound card Video card === Control unit === The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into control signals that activate other parts of the computer. Control systems in advanced computers may change the order of execution of some instructions to improve performance. A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from. The control system's function is as follows— this is a simplified description, and some of these steps may be performed concurrently or in a different order depending on the type of CPU: Read the code for the next instruction from the cell indicated by the program counter. Decode the numerical code for the instruction into a set of commands or signals for each of the other systems. Increment the program counter so it points to the next instruction. Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code. Provide the necessary data to an ALU or register. If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation. Write the result from the ALU back to a memory location or to a register or perhaps an output device. Jump back to step (1). Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow). The sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program, and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer, which runs a microcode program that causes all of these events to happen. === Central processing unit (CPU) === The control unit, ALU, and registers are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components. Since the 1970s, CPUs have typically been constructed on a single MOS integrated circuit chip called a microprocessor. === Arithmetic logic unit (ALU) === The ALU is capable of performing two classes of operations: arithmetic and logic. The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division, trigonometry functions such as sine, cosine, etc., and square roots. Some can operate only on whole numbers (integers) while others use floating point to represent real numbers, albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return Boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?"). Logic operations involve Boolean logic: AND, OR, XOR, and NOT. These can be useful for creating complicated conditional statements and processing Boolean logic. Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously. Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices. === Memory === A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595." The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is the software's responsibility to give significance to what the memory sees as nothing but a series of numbers. In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers (28 = 256); either from 0 to 255 or −128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory. The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. As data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed. Computer main memory comes in two principal varieties: random-access memory or RAM read-only memory or ROM RAM can be read and written to anytime the CPU commands it, but ROM is preloaded with data and software that never changes, therefore the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM are erased when the power to the computer is turned off, but ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the required software may be stored in ROM. Software stored in ROM is often called firmware, because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary. In more sophisticated computers there may be one or more RAM cache memories, which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part. === Input/output (I/O) === I/O is the means by which a computer exchanges information with the outside world. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O. I/O devices are often complex computers in their own right, with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O. A 2016-era flat screen display contains its own computer circuitry. === Multitasking === While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt, which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time". then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn. Before the era of inexpensive computers, the principal use for multitasking was to allow many people to share the same computer. Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly, in direct proportion to the number of programs it is running, but most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run simultaneously without unacceptable speed loss. === Multiprocessing === Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed in only large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result. Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general-purpose computers. They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful for only specialized tasks due to the large scale of program organization required to use most of the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks. == Software == Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. Software is that part of a computer system that consists of encoded information or computer instructions, in contrast to the physical hardware from which the system is built. Computer software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. It is often divided into system software and application software. Computer hardware and software require each other and neither can be realistically used on its own. When software is stored in hardware that cannot easily be modified, such as with BIOS ROM in an IBM PC compatible computer, it is sometimes called "firmware". === Languages === There are thousands of different programming languages—some intended for general purpose, others useful for only highly specialized applications. === Programs === The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that some type of instructions (the program) can be given to the computer, and it will process them. Modern computers based on the von Neumann architecture often have machine code in the form of an imperative programming language. In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second (gigaflops) and rarely makes a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers years to write, and due to the complexity of the task almost certainly contain errors. ==== Stored program architecture ==== This section applies to most common RAM machine–based computers. In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to the instruction following that jump instruction. Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention. Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time, with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. The following example is written in the MIPS assembly language: Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in a fraction of a second. ==== Machine code ==== In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode; the command to multiply them would have a different opcode, and so on. The simplest computers are able to perform any of a handful of different instructions; the more complex computers have several hundred to choose from, each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of these instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer in the same way as numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches. While it is possible to write computer programs as long lists of numbers (machine language) and while this technique was used with many early computers, it is extremely tedious and potentially error-prone to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember – a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler. ==== Programming language ==== Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine code by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques. ===== Low-level languages ===== Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) are generally unique to the particular architecture of a computer's central processing unit (CPU). For instance, an ARM architecture CPU (such as may be found in a smartphone or a hand-held videogame) cannot understand the machine language of an x86 CPU that might be in a PC. Historically a significant number of other cpu architectures were created and saw extensive use, notably including the MOS Technology 6502 and 6510 in addition to the Zilog Z80. ===== High-level languages ===== Although considerably easier than in machine language, writing long programs in assembly language is often difficult and is also error prone. Therefore, most practical programs are written in more abstract high-level programming languages that are able to express the needs of the programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler. High level languages are less related to the workings of the target computer than assembly language, and more related to the language and structure of the problem(s) to be solved by the final program. It is therefore often possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles. ==== Program design ==== Program design of small programs is relatively simple and involves the analysis of the problem, collection of inputs, using the programming constructs within languages, devising or using established procedures and algorithms, providing data for output devices and solutions to the problem as applicable. As problems become larger and more complex, features such as subprograms, modules, formal documentation, and new paradigms such as object-oriented programming are encountered. Large programs involving thousands of line of code and more require formal software methodologies. The task of developing large software systems presents a significant intellectual challenge. Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult; the academic and professional discipline of software engineering concentrates specifically on this challenge. ==== Bugs ==== Errors in computer programs are called "bugs". They may be benign and not affect the usefulness of the program, or have only subtle effects. However, in some cases they may cause the program or the entire system to "hang", becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash. Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit, code designed to take advantage of a bug and disrupt a computer's proper execution. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design. Admiral Grace Hopper, an American computer scientist and developer of the first compiler, is credited for having first used the term "bugs" in computing after a dead moth was found shorting a relay in the Harvard Mark II computer in September 1947. == Networking and the Internet == Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems such as Sabre. In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments. == Unconventional computers == A computer does not need to be electronic, nor even have a processor, nor RAM, nor even a hard disk. While popular usage of the word "computer" is synonymous with a personal electronic computer, a typical modern definition of a computer is: "A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information." According to this definition, any device that processes information qualifies as a computer. == Future == There is active research to make non-classical computers out of many promising new types of technology, such as optical computers, DNA computers, neural computers, and quantum computers. Most computers are universal, and are able to calculate any computable function, and are limited only by their memory capacity and operating speed. However different designs of computers can give very different performance for particular problems; for example quantum computers can potentially break some modern encryption algorithms (by quantum factoring) very quickly. === Computer architecture paradigms === There are many types of computer architectures: Quantum computer vs. Chemical computer Scalar processor vs. Vector processor Non-Uniform Memory Access (NUMA) computers Register machine vs. Stack machine Harvard architecture vs. von Neumann architecture Cellular architecture Of all these abstract machines, a quantum computer holds the most promise for revolutionizing computing. Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms. The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, any type of computer (netbook, supercomputer, cellular automaton, etc.) is able to perform the same computational tasks, given enough time and storage capacity. === Artificial intelligence === A computer will solve problems in exactly the way it is programmed to, without regard to efficiency, alternative solutions, possible shortcuts, or possible errors in the code. Computer programs that learn and adapt are part of the emerging field of artificial intelligence and machine learning. Artificial intelligence based products generally fall into two major categories: rule-based systems and pattern recognition systems. Rule-based systems attempt to represent the rules used by human experts and tend to be expensive to develop. Pattern-based systems use data about a problem to generate conclusions. Examples of pattern-based systems include voice recognition, font recognition, translation and the emerging field of on-line marketing. == Professions and organizations == As the use of computers has spread throughout society, there are an increasing number of careers involving computers. The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature. == See also == == Notes == == References == == Sources == == External links == Media related to Computers at Wikimedia Commons Wikiversity has a quiz on this article

A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations (computation). Modern digital electronic computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware, operating system, software, and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network or computer cluster. A broad range of industrial and consumer products use computers as control systems, including simple special-purpose devices like microwave ovens and remote controls, and factory devices like industrial robots. Computers are at the core of general-purpose devices such as personal computers and mobile devices such as smartphones. Computers power the Internet, which links billions of computers and users. Early computers were meant to be used only for calculations. Simple manual instruments like the abacus have aided people in doing calculations since ancient times. Early in the Industrial Revolution, some mechanical devices were built to automate long, tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century. The first digital electronic calculating machines were developed during World War II, both electromechanical and using thermionic valves. The first semiconductor transistors in the late 1940s were followed by the silicon-based MOSFET (MOS transistor) and monolithic integrated circuit chip technologies in the late 1950s, leading to the microprocessor and the microcomputer revolution in the 1970s. The speed, power, and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (Moore's law noted that counts doubled every two years), leading to the Digital Revolution during the late 20th and early 21st centuries. Conventionally, a modern computer consists of at least one processing element, typically a central processing unit (CPU) in the form of a microprocessor, together with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen). Peripheral devices allow information to be retrieved from an external source, and they enable the results of operations to be saved and retrieved.

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Computer (disambiguation) (wikipedia)

A computer is a programmable machine that can perform arithmetic and logical operations. Computer may also refer to: Computer (Courage the Cowardly Dog), a character in the American animated television series Computer (magazine), a magazine published by the Institute of Electrical and Electronics Engineers Computer (occupation) Analog computer OK Computer, a 1997 Radiohead album Personal computer (PC) The Computer (or Friend Computer), a character in the role-playing game Paranoia Enock Mwepu (born 1998), Gambian retired professional footballer. Nicknamed 'The Computer' for his ability to read the game. "Computers" (Don't Hug Me I'm Scared), an episode of Don't Hug Me I'm Scared

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Computer (magazine) (wikipedia)

Computer is an IEEE Computer Society practitioner-oriented magazine issued to all members of the society. It contains peer-reviewed articles, regular columns, and interviews on current computing-related issues. Computer provides information regarding current research developments, trends, best practices, and changes in the computing profession. Subscriptions of the magazine are provided free of cost to IEEE Computer Society members. Computer covers all aspects of computer science. Since 2009, it has a digital edition too. The current editor in chief (since 1 January 2020) is Jeff Voas of NIST. Its impact factor was 1.94 for 2017, and 3.564 for 2018. The magazine is the recipient of the 2015 APEX Award for Publication Excellence. Computer won the 2018 Folio: Eddie Award for its September 2017 issue, "Blockchain Technology in Finance", in the category of Association/Nonprofit, App/Digital Edition. Computer also received Folio: Eddie Digital Award honorable mentions in 2019, 2017, and 2016. == References == == External links == Official website DBLP bibliography (partial from 1975 volume 8, complete from 1988 volume 21) IEEE Computer Society

Computer is an IEEE Computer Society practitioner-oriented magazine issued to all members of the society. It contains peer-reviewed articles, regular columns, and interviews on current computing-related issues. Computer provides information regarding current research developments, trends, best practices, and changes in the computing profession. Subscriptions of the magazine are provided free of cost to IEEE Computer Society members. Computer covers all aspects of computer science. Since 2009, it has a digital edition too. The current editor in chief (since 1 January 2020) is Jeff Voas of NIST. Its impact factor was 1.94 for 2017, and 3.564 for 2018. The magazine is the recipient of the 2015 APEX Award for Publication Excellence. Computer won the 2018 Folio: Eddie Award for its September 2017 issue, "Blockchain Technology in Finance", in the category of Association/Nonprofit, App/Digital Edition. Computer also received Folio: Eddie Digital Award honorable mentions in 2019, 2017, and 2016.

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Computer (occupation) (wikipedia)

The term "computer", in use from the early 17th century (the first known written reference dates from 1613), meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available. Alan Turing described the "human computer" as someone who is "supposed to be following fixed rules; he has no authority to deviate from them in any detail." Teams of people, often women from the late nineteenth century onwards, were used to undertake long and often tedious calculations; the work was divided so that this could be done in parallel. The same calculations were frequently performed independently by separate teams to check the correctness of the results. Since the end of the 20th century, the term "human computer" has also been applied to individuals with prodigious powers of mental arithmetic, also known as mental calculators. == Origins in sciences == Astronomers in Renaissance times used that term about as often as they called themselves "mathematicians" for their principal work of calculating the positions of planets. They often hired a "computer" to assist them. For some men, such as Johannes Kepler, assisting a scientist in computation was a temporary position until they moved on to greater advancements. Before he died in 1617, John Napier suggested ways by which "the learned, who perchance may have plenty of pupils and computers" might construct an improved logarithm table.: p.46 Computing became more organized when the Frenchman Alexis Claude Clairaut (1713–1765) divided the computation to determine the time of the return of Halley's Comet with two colleagues, Joseph Lalande and Nicole-Reine Lepaute. Human computers continued plotting the future movements of astronomical objects to create celestial tables for almanacs in the late 1760s. The computers working on the Nautical Almanac for the British Admiralty included William Wales, Israel Lyons and Richard Dunthorne. The project was overseen by Nevil Maskelyne. Maskelyne would borrow tables from other sources as often as he could in order to reduce the number of calculations his team of computers had to make. Women were generally excluded, with some exceptions such as Mary Edwards who worked from the 1780s to 1815 as one of thirty-five computers for the British Nautical Almanac used for navigation at sea. The United States also worked on their own version of a nautical almanac in the 1840s, with Maria Mitchell being one of the best-known computers on the staff. Other innovations in human computing included the work done by a group of boys who worked in the Octagon Room of the Royal Greenwich Observatory for Astronomer Royal George Airy. Airy's computers, hired after 1835, could be as young as fifteen, and they were working on a backlog of astronomical data. The way that Airy organized the Octagon Room with a manager, pre-printed computing forms, and standardized methods of calculating and checking results (similar to the way the Nautical Almanac computers operated) would remain a standard for computing operations for the next 80 years. Women were increasingly involved in computing after 1865. Private companies hired them for computing and to manage office staff. In the 1870s, the United States Signal Corps created a new way of organizing human computing to track weather patterns. This built on previous work from the US Navy and the Smithsonian meteorological project. The Signal Corps used a small computing staff that processed data that had to be collected quickly and finished in "intensive two-hour shifts". Each individual human computer was responsible for only part of the data. In the late nineteenth century Edward Charles Pickering organized the "Harvard Computers". The first woman to approach them, Anna Winlock, asked Harvard Observatory for a computing job in 1875. By 1880, all of the computers working at the Harvard Observatory were women. The standard computer pay started at twenty-five cents an hour. There would be such a huge demand to work there, that some women offered to work for the Harvard Computers for free. Many of the women astronomers from this era were computers with possibly the best-known being Florence Cushman, Henrietta Swan Leavitt, and Annie Jump Cannon, who worked with Pickering from 1888, 1893, and 1896 respectively. Cannon could classify stars at a rate of three per minute. Mina Fleming, one of the Harvard Computers, published The Draper Catalogue of Stellar Spectra in 1890. The catalogue organized stars by spectral lines. The catalogue continued to be expanded by the Harvard Computers and added new stars in successive volumes. Elizabeth Williams was involved in calculations in the search for a new planet, Pluto, at the Lowell Observatory. In 1893, Francis Galton created the Committee for Conducting Statistical Inquiries into the Measurable Characteristics of Plants and Animals which reported to the Royal Society. The committee used advanced techniques for scientific research and supported the work of several scientists. W.F. Raphael Weldon, the first scientist supported by the committee worked with his wife, Florence Tebb Weldon, who was his computer. Weldon used logarithms and mathematical tables created by August Leopold Crelle and had no calculating machine. Karl Pearson, who had a lab at the University of London, felt that the work Weldon did was "hampered by the committee". However, Pearson did create a mathematical formula that the committee was able to use for data correlation. Pearson brought his correlation formula to his own Biometrics Laboratory. Pearson had volunteer and salaried computers who were both men and women. Alice Lee was one of his salaried computers who worked with histograms and the chi-squared statistics. Pearson also worked with Beatrice and Frances Cave-Brown-Cave. Pearson's lab, by 1906, had mastered the art of mathematical table making. == Mathematical tables == Human computers were used to compile 18th and 19th century Western European mathematical tables, for example those for trigonometry and logarithms. Although these tables were most often known by the names of the principal mathematician involved in the project, such tables were often in fact the work of an army of unknown and unsung computers. Ever more accurate tables to a high degree of precision were needed for navigation and engineering. Approaches differed, but one was to break up the project into a form of piece work completed at home. The computers, often educated middle class women whom society deemed it unseemly to engage in the professions or go out to work, would receive and send back packets of calculations by post. The Royal Astronomical Society eventually gave space to a new committee, the Mathematical Tables Committee, which was the only professional organization for human computers in 1925. == Fluid dynamics == Human computers were used to predict the effects of building the Afsluitdijk between 1927 and 1932 in the Zuiderzee in the Netherlands. The computer simulation was set up by Hendrik Lorentz. A visionary application to meteorology can be found in the scientific work of Lewis Fry Richardson who, in 1922, estimated that 64,000 humans could forecast the weather for the whole globe by solving the attending differential primitive equations numerically. Around 1910 he had already used human computers to calculate the stresses inside a masonry dam. == Wartime computing and electronics == It was not until World War I that computing became a profession. "The First World War required large numbers of human computers. Computers on both sides of the war produced map grids, surveying aids, navigation tables and artillery tables. With the men at war, most of these new computers were women and many were college educated." This would happen again during World War II, as more men joined the fight, college educated women were left to fill their positions. One of the first female computers, Elizabeth Webb Wilson, was hired by the Army in 1918 and was a graduate of George Washington University. Wilson "patiently sought a war job that would make use of her mathematical skill. In later years, she would claim that the war spared her from the 'Washington social whirl', the rounds of society events that should have procured for her a husband" and instead she was able to have a career. After the war, Wilson continued with a career in mathematics and became an actuary and turned her focus to life tables. Human computers played integral roles in the World War II war effort in the United States, and because of the depletion of the male labor force due to the draft, many computers during World War II were women, frequently with degrees in mathematics. In the 1940s, women were hired to examine nuclear and particle tracks left on photographic emulsions. In the Manhattan Project, human computers working with a variety of mechanical aids assisted numerical studies of the complex formulas related to nuclear fission. Human computers were involved in calculating ballistics tables during World War I. Between the two world wars, computers were used in the Department of Agriculture in the United States and also at Iowa State College. The human computers in these places also used calculating machines and early electrical computers to aid in their work. In the 1930s, The Columbia University Statistical Bureau was created by Benjamin Wood. Organized computing was also established at Indiana University, the Cowles Commission and the National Research Council. Following World War II, the National Advisory Committee for Aeronautics (NACA) used human computers in flight research to transcribe raw data from celluloid film and oscillograph paper and then, using slide rules and electric calculators, reduced the data to standard engineering units. Margot Lee Shetterly's biographical book, Hidden Figures (made into a movie of the same name in 2016), depicts African-American women who served as human computers at NASA in support of the Friendship 7, the first American crewed mission into Earth orbit. NACA had begun hiring black women as computers from 1940. One such computer was Dorothy Vaughan who began her work in 1943 with the Langley Research Center as a special hire to aid the war effort, and who came to supervise the West Area Computers, a group of African-American women who worked as computers at Langley. Human computing was, at the time, considered menial work. On November 8, 2019, the Congressional Gold Medal was awarded "In recognition of all the women who served as computers, mathematicians, and engineers at the National Advisory Committee for Aeronautics and the National Aeronautics and Space Administration (NASA) between the 1930s and the 1970s." As electrical computers became more available, human computers, especially women, were drafted as some of the first computer programmers. Because the six people responsible for setting up problems on the ENIAC (the first general-purpose electronic digital computer built at the University of Pennsylvania during World War II) were drafted from a corps of human computers, the world's first professional computer programmers were women, namely: Kay McNulty, Betty Snyder, Marlyn Wescoff, Ruth Lichterman, Betty Jean Jennings, and Fran Bilas. == Human-assisted computation == The term "human computer" has been recently used by a group of researchers who refer to their work as "human computation". In this usage, "human computer" refers to activities of humans in the context of human-based computation (HBC). This use of "human computer" is debatable for the following reason: HBC is a computational technique where a machine outsources certain parts of a task to humans to perform, which are not necessarily algorithmic. In fact, in the context of HBC most of the time humans are not provided with a sequence of exact steps to be executed to yield the desired result; HBC is agnostic about how humans solve the problem. This is why "outsourcing" is the term used in the definition above. The use of humans in the historical role of "human computers" for HBC is very rare. == See also == Difference engine – an early automatic mechanical calculator designed to replace human computers Mathematical Tables Project – a project of the Works Progress Administration (WPA) that employed human computers Mentat – fictional human computers in the Dune universe Women in computing == Notes == == References == == External links == Early NACA human computers at work, photograph, October 1949. The Age of Female Computers Archived June 16, 2006, at the Wayback Machine, by David Skinner Sonoma State University Archived April 22, 2021, at the Wayback Machine Wellesley Description of model of H. A. Lorentz

The term "computer", in use from the early 17th century (the first known written reference dates from 1613), meant "one who computes": a person performing mathematical calculations, before electronic computers became commercially available. Alan Turing described the "human computer" as someone who is "supposed to be following fixed rules; he has no authority to deviate from them in any detail." Teams of people, often women from the late nineteenth century onwards, were used to undertake long and often tedious calculations; the work was divided so that this could be done in parallel. The same calculations were frequently performed independently by separate teams to check the correctness of the results. Since the end of the 20th century, the term "human computer" has also been applied to individuals with prodigious powers of mental arithmetic, also known as mental calculators.

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List of Courage the Cowardly Dog characters (wikipedia)

This is a list of characters from the Cartoon Network animated series, Courage the Cowardly Dog. == Main characters == === Courage === Voiced by Howard Hoffman (pilot) and Marty Grabstein (series; "The Fog of Courage"; Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog) Courage is the titular character and protagonist of the series. He is a kind, yet easily frightened dog who was abandoned as a puppy after his parents were sent into outer space, but was adopted by Muriel Bagge. Her husband Eustace regularly mistreats him. Ironically, given his name, Courage is a genuine coward and he often expresses his distress with over-the-top, piercing shrieks. Regardless, he still goes to great lengths to protect his owners. To the end, he often gets injured, sometimes quite brutally, and only surviving through his determination and/or pure luck. Despite his cowardice, Courage is very clever and resourceful when the situation demands it, outsmarting the villains most of the time. He also often displays super strength, carrying Muriel and Eustace with relative ease. Aiding him at saving the day is a self-aware, sarcastic and seemingly omniscient computer that he keeps in the attic. He got his name when Muriel found him as a puppy alone in an alley and remarked that he must be quite brave to be there by himself. === Muriel Bagge === Voiced by Howard Hoffman (pilot) and Thea White (series; "The Fog of Courage"; Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog). Muriel Bagge is Courage's owner and Eustace's wife. She is a plump, kind, hardworking Scottish woman who took Courage in when he was an abandoned puppy. Muriel often carries a rolling pin that she hits Eustace with whenever he harasses Courage. She also likes tea and usually tends to her garden, as well as being an accomplished sitar player. Muriel also has a great fondness for cooking; however, her recipes tend to include an excessive amount of vinegar, much to the distaste of both her dog and husband. Most of all, she loves sitting in her rocking chair with Courage on her lap and watching television. Due to her kindness and sweet nature, Muriel is an easy (and often attractive) target for villains. The crossover movie Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog was White’s final role before she died of liver cancer in 2021. === Eustace Bagge === Voiced by Howard Hoffman (pilot), Lionel Wilson (Episodes 1–33), Arthur Anderson (Episodes 34–52), Wallace Shawn ("The Fog of Courage"), and Jeff Bergman (Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog) Eustace Bagge is Muriel's husband. He is an elderly, skinny, greedy, cynical, and sarcastic American man who is obsessed with his vintage truck. Eustace wears glasses identical in appearance to Muriel's. His brown hat shields his glistening bald head. Eustace is the current owner of the farmhouse, which was previously owned by his now-deceased brother Horst. Eustace regularly yells at Courage and calls him a "Stupid dog!" He regularly dismisses Muriel as well, but he still does love his wife, as evidenced by his concern for her well-being in a few episodes, like "The Demon in the Mattress". Lionel Wilson originally voiced the character, but left midway through the third season due to illness (and eventually died five months after the show ended) and was replaced by Arthur Anderson. However, many vocals and sounds of grunts, laughs, screams and catchphrases from Wilson have been used while Anderson was recording. In the 2014 short titled The Fog of Courage, Wallace Shawn replaced Anderson as the voice of Eustace. In the crossover special with Scooby-Doo, Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog, veteran voice actor Jeff Bergman plays Eustace. == Supporting characters == === Courage's Computer === Voiced by Simon Prebble (series), Paul Schoeffler ("The Fog of Courage") and Jeff Bergman (Straight Outta Nowhere: Scooby-Doo! Meets Courage the Cowardly Dog) Courage's computer that speaks with an English accent and gives him advice on how to deal with crazy situations. Located in the farmhouse attic, he is very cynical and sarcastic towards Courage and has a habit of regularly cracking jokes in any situation. The Computer also appears to often provide Courage with sarcastic and unhelpful advice. === Dr. Vindaloo === Voiced by Paul Schoeffler Dr. Vindaloo is an Indian doctor with a thick accent, whom Eustace and Muriel see when something is wrong. He is one of the few characters in the series who can perfectly understand what Courage is trying to say. He diagnoses his patients as not having serious problems or that there is nothing that he can do, but has, on occasion, been a great help. He often quotes “There’s nothing to worry about. Nothing at all” when questioned about certain health conditions or situations. === Ma Bagge === Voiced by Billie Lou Watt Ma Bagge is the mother of Eustace and Horst and Muriel's mother-in-law, who shares a love-hate relationship with the former, usually calling him "Stupid Boy". She lives in a trailer and is the widow of Icket Bagge (Eustace’s father). Like Eustace, she is actually bald but wears a wig and looks almost identical to her son, but much shorter, along with being insecure due to being bald, but she does have her teeth. It is learned that Ma and Horst's ill treatment was part of Eustace's negative personality. She tends to treat Courage kindly whenever Eustace is around, possibly because she knows it annoys him, though she also has a love-hate relationship with him, and calls him "Stupid Dog" just like Eustace does. She's also the owner of Growth Industries, a company that produces wigs and experiments on certain people with a rare blood type, one that Muriel has. === Shirley the Medium === Voiced by Mary Testa Shirley the Medium is a small green Chihuahua garbed as a stereotypical Gypsy fortune-teller who resides in a dilapidated caravan. She has a strong dislike of Eustace (whom she always refers to as "the stupid one") because he of his greed and selfishness. Due to this she often places Eustace under curses to get him to be a better person. Shirley is one of Courage's three confidants, the others being the Computer and Dr. Vindaloo, and helps him occasionally by casting and reciting spells and playing the saxophone in-between verses. == Major villains == === Katz === Voiced by Paul Schoeffler Katz is a red, lanky anthropomorphic cat with a posh English accent. He is Courage's nemesis and the show's most recurring antagonist, though Muriel and Eustace consistently fail to recognize him. He specializes in scam businesses and is extremely sadistic. Many of his businesses involve torturing or outright killing his customers; for example, in "Night at the Katz Motel," he fed his motel residents to flesh-eating spiders, and in "Klub Katz," he transformed the vacationers into anthropomorphic machines to fight for him gladiator-style. All of his businesses enforce a strict "No Dogs Allowed" policy, forcing Courage to sneak in. He often challenges Courage to ironically banal games such as wall-ball and staring contests, which Courage invariably loses; nevertheless, he is always defeated in the end. Unlike the rest of the series villains, he is frequently accompanied by his own theme, which consists of a sinister hip-hop beat. === Le Quack === Voiced by Paul Schoeffler Le Quack is a French con-duck, who first appears early in the show's first season, in which he has a fake amnesia-specialist license; he comes to the Bagges' house when Muriel suffers from amnesia. Since then, he frequently returns and manages to dupe Courage's owners into helping him commit crime sprees. Le Quack is also shown to be capable of escaping custody such as when he was first arrested, crashing the police car in the process, and later causes a fire at prison. === Di Lung === Voiced by Tim Chi Ly Di Lung is a young Chinese-American inventor. He also likes to verbally and physically abuse Courage whenever he sees him, and often does his experiments on him. He made his debut appearance in the episode "Hothead". He is very inconsiderate and rude and usually gets caught in the middle of the chaos happening in Nowhere, prompting him to shout his catchphrase of "Watch where you're going, ya foo!", which is a running gag in the series, considering the fact that he uses said phrase hypocritically, when he is clearly in the wrong despite claiming that the other person is wrong. He is the inventor of Mecha Courage. Di Lung also has two aunts: one good and one bad, who are both the Empresses of China; thus, this could make him royalty. == Minor villains == === Benton Tarantella and Errol Von Volkheim === Voiced by Peter Fernandez (Benton) and Paul Schoeffler (Errol) Benton Tarantella (a pun of Quentin Tarantino) and Errol Von Volkheim (a pun of Erich Von Stroheim and Errol Flynn) are a zombified duo of murderers/snuff film directors. They would pose as ordinary movie producers to lure unsuspecting victims to their fates, killing them in the process as part of their ‘film’. Tarantella returns in the episode, "Angry Nasty People", when he uses his camera to capture Eustace's nastiness towards Courage and Muriel, creating another version of Eustace named "Mr. Nasty." === Buschwick === Voiced by Andre Sogliuzzo Buschwick (though he bans people from calling him that, ordering everybody to refer to him as simply "Schwick") is a giant, shady cockroach who comes from a New York City neighborhood of the same name. He appears in the episode "Courage in the Big Stinkin' City" and invites Muriel, along with Courage and Eustace, backstage at Radio City Music Hall that is close to Rockefeller Center in Midtown Manhattan in New York City, New York so that Muriel can rehearse for a sitar concert which was a prize that she won in a contest. Bushwick sends Courage away to retrieve an evil package, threatening to sentence Muriel to be a victim of an unseen monster behind a locked door if he does not receive the package before curtain time, adding that the dog better not get the police involved, which also results in Muriel's demise. He gets arrested by the New York City Police Department police officer in the end, however, while Courage and Muriel gets her concert. === Buschwick's pet === Buschwick owns a pet that is locked behind a mousehole-door in his rehearsal room. The unseen monster is responsible for the demise of previous visitors who entered the room (their bones are visible inside) and he warns Courage to recover his package before the curtain rises, without involving law enforcement, otherwise he will release the monster on Muriel. Courage acquires the item, but the insect finds that the contents are damaged, causing him to release the creature, attempting to kill Muriel. Courage and Muriel escape unharmed, but the creature devours Eustace. === The Chicken from Outer Space === Voiced by Howard Hoffman The Chicken from Outer Space is the show's first villain, introduced by the pilot episode of the same name. His eggs are unlike regular chicken eggs as they have red spots with a red yolk, are mutagenic and whoever eats them will turn into one. In his first appearance, he tries to take over the farm, he lays eggs in the chicken coop which were eaten by Eustace and ends up being shot by his own laser gun, turning into a headless roast chicken. He later returns in "The Revenge of The Chicken from Outer Space" where he wants to use a plunger to rip off Courage's head and put it on his roasted body. He ends up ripping off Eustace's head and tries to destroy Courage but is then blown up in his space ship when a rocket blasts into it. In "Son of the Chicken from Outer Space", his three-headed son is sent to Earth to avenge him and kill Courage. Unfortunately, like their father, they are no match for the timid dog and fear that they will never be able to go home until Courage is dead. Feeling sympathy for them, Courage helps them by taking fake pictures to make it look like they succeeded in killing him and fool their mother into thinking that their mission was a success. === The Snowman === Voiced by Paul Schoeffler The Snowman is a talking snowman believed to be the last of his kind due to global warming. In his first appearance, he tries to steal Eustace and Muriel's "anti-melting" gene. He returns in the episode "The Snowman's Revenge" where he turns the farmhouse into the West Pole and freezes Courage and his owners, however he reveals how he lost his home and friends. He has a voice pattern like that of the Scottish actor Sean Connery. === The Cajun Fox === Voiced by Paul Schoeffler The Cajun Fox is a sunglass-wearing fox obsessed with cooking who appears in the episode “Cajun Granny Stew”. He kidnaps Muriel in order to make a stew, using her as the final ingredient, but he ends up falling into the pot of stew himself when Courage falls on top of him and Muriel just as he is about to throw Muriel into the pot. === Freaky Fred === Voiced by Paul Schoeffler Freaky Fred is Muriel's creepy nephew who was sent to the "home for freaky barbers", due to his obsession with cutting the hair of people or animals to the point that they are bald. He speaks in poems and rhymes often repeating the word ‘naughty’ when describing certain situations. === The Clutching Foot === Voiced by Paul Schoeffler The Clutching Foot is a strange foot fungus that Eustace contracts before mutating into a sentient being. It resembles a giant purple left foot with heads for toes and acts as if it were a stereotypical criminal mob, with the big toe as the kingpin, and the smaller toes as his goons. It orders Courage to carry out crimes during the episode. === Dr. Gerbil === Voiced by John R. Dilworth Dr. Gerbil is a gerbil who speaks with a Southern accent, who has gone mad due to being experimented on and being trapped by his previous owners. He is now a mad scientist, who performs strange experiments on humans with homemade cosmetic products, because he believes that he needs to exact revenge on humans for what they do to animals. === Dr. Žalost === Voiced by Paul Schoeffler Dr. Žalost is "the greatest unhappy scientist who ever lived" who lives in a giant, moving tower. He lives with his assistant, Rat, whom he constantly asks for a hug. He demands 33⅓ billion dollars from the city of Nowhere to fund his "Unhappy Cannonball" project, only to be brushed off by the city's officials as a scam artist. In retaliation, Žalost attacks the city by firing unhappy cannonballs from his mobile tower, making the citizens of the city depressed and unproductive. Despite receiving his money in the end, he refuses to return the inhabitants of the city to normal, as he is jealous of the happiness of others. He then turns his attention towards the Bagge family, determined to inflict sadness and depression on all of the inhabitants of Nowhere. His name Žalost is a word of Croatian, Serbian, Bosnian, or Slovenian origin meaning "sorrow" or "sadness". === The Goose God === Voiced by Paul Schoeffler The Goose God is an anthropomorphic goose who came down from the heavens to search for the woman of his dreams, and ended up falling in love with Muriel, whom he competed with Courage and Eustace to make his wife and queen (even though Eustace is completely unaware this is happening). He later falls for Eustace's truck after hearing it honk. He has made cameos in various other episodes (usually lying on top of the truck). === Jeeves Weevil === Voiced by Paul Schoeffler Jeeves Weevil is a giant, polite, blood-sucking weevil who wears a blue tuxedo and hat. When the Bagges accidentally run him over with their truck and injure him, he is accepted into their home. While a seeming gentleman, he begins to suck the life out of the ever-oblivious Muriel and Eustace. He does not suck out dogs' lives, so Courage is unharmed. He succeeds at sucking out Eustace's life. === The King of Flan === Voiced by Jorge Pupo The King of Flan is a man with a Spanish accent and the proprietor of a company that makes flan. He produces a TV commercial that uses hypnotism to attract customers, all of whom become morbidly obese after eating too much flan. Courage comes to stop The King of Flan from broadcasting on all the networks, and causes The King to accidentally hypnotize himself. The company is located at 1 Flan Drive in Flansville, Kansas. === King Ghidorah === This is a 3-headed dragon that does not actually play a villainous role, but is present in 'Courage in the Big Stinkin' City' as a creature hidden behind a door inside an apartment block that Courage enters to search for a package for Schwick. === King Ramses === Voiced by series creator John R. Dilworth King Ramses is the ghost of a pharaoh from ancient Egypt. Two cat grave robbers steal a slab (decorated with images of King Ramses and pictures corresponding to each of his three curses) from his tomb and flee to Nowhere, but Ramses appears and demands the return of his slab. They refuse, so Ramses summons a swarm of locusts. He later attacks the farm when Courage finds the slab and Eustace refuses to return it after discovering it is worth a fortune, summoning a flood of water, a loud record player, and locusts. Eustace finally gives in and Courage throws the slab out of the house. After Eustace reclaims it, Ramses unleashes one final curse that imprisons Eustace in the slab as it is returned to Ramses's crypt the next day. === Mayan Baker === Voiced by Daniel Oreskes Mayan Baker, who appeared in the episode "Courage Meets the Mummy", is the reanimated corpse of a Mayan royal baker. In ancient times, the baker served cookies to the Mayan princess until she falsely accused him of stealing cookies and selling them to villagers for money, but the thief was really her trusted royal poobah. Thousands of years later, Professor Frith accidentally resurrected the Mummy. After attacking him, the Mummy decided to take revenge against Eustace and Muriel. He mistakes them for the princess and poobah. With some setbacks, the Mummy finally arrives at the farm where Courage hypnotized Eustace and Muriel into thinking they were the Mayan Princess and the Poobah. After recreating the situation from thousands of years earlier, Courage surmised that the Baker was framed by the Poobah. Satisfied, the Mummy decides to return to his tomb to eternally rest in peace when Muriel gives him Eustace's polka-dotted blanket for his entombment. === Mad Dog === Voiced by Peter Fernandez Mad Dog is a Doberman and the fierce leader of an evil dog-gang who began dating Bunny until Courage came to her rescue. He is shown to be possessive and abusive towards Bunny to the point of forcing her to not see her best friend Kitty, as he will bury both of them if they are seen together. === Mecha Courage === Voiced by John R. Dilworth Mecha Courage is a robotic version of Courage that was created by Di Lung in an attempt to prove that he has created a dog that is superior to Courage in every way. Mecha Courage resembles a mini-dome, colored pink with a purple underside and tail, on wheels, with a red, blinking light for a nose. === Mr. Nasty === Voiced by Arthur Anderson Mr. Nasty is a character created by Benton Tarantella from Eustace's true evil essence. He is similar to Eustace (both in identity and personality), only with sunglasses in place of his eyeglasses, blue skin, and a deeper voice. After Mr. Nasty is brought into existence, he co-stars in Tarantella's reality TV show Angry Nasty People alongside Eustace, in which they both mistreat Courage and Muriel. === Mustafa al Bacterius === Voiced by Arnold Stang Mustafa al Bacterius is an alien worm who appears in "Mission to the Sun". When Courage and the Bagges are sent on a mission to prevent the Sun from burning out, Bacterius attempts to sabotage their mission by firstly infecting and controlling Muriel's mind, and then using her to destroy their spaceship. Eventually, he is sucked out of the ship through the toilet and infects Eustace at the end of the episode. === The Queen of the Black Puddle === Voiced by Ruth Williamson The Queen of the Black Puddle is an otherworldly siren temptress who resides within a supernatural black puddle. Her sinister goals are to seduce men gradually until she eventually manages to guide them to her puddle, where she eats them. She appeared in the episode of the same name where she successfully manages to charm Eustace and almost succeeds in devouring him, but Courage triumphs over her. At the episode's end, when Courage is bathing, a canine version of the Queen of the Black Puddle appears from the bath water, leaving Courage confused and puzzled. She later returns as part of a large villain supergroup to get rid of Courage in the episode “Ball of Revenge”. === King Kong === Voiced by Paul Schoeffler King Kong is a large ape who appears in the episode "1,000 Years of Courage". When Courage and his owners are sent to a future Earth inhabited by talking banana people, the Big Ape poses as the Banana God in order to devour the banana people, while his nephew disguises himself as a benevolent sovereign. At the conclusion of the episode, both monkeys are musicians for the banana people. === Cruel Veterinarian === Voiced by George Hall The Cruel Veterinarian is the main antagonist of the episode "Remembrance of Courage Past", and the only veterinarian who was responsible for separating Courage from his parents as a puppy. He manipulated Courage's parents into talking with them alone, which was revealed to be a trick as he captured them. Courage followed the evil veterinarian to his secret lab as it was revealed that he was shoving and locking them in a rocket ship. This was as part of his secret breeding experiment, to see that normal dogs (in space) would breed space dogs. However, Courage attempted to save his parents, but is spotted by the vet, who chases him in the lab, finally going down a garbage chute to avoid being captured by the vet. He watches as his parents were sent to space, saddened that he couldn't save them. He was later adopted by Muriel. Years later, Muriel and Eustace took Courage (still traumatized by the events) to the same vet that kidnapped and launched his parents, after recognizing him from the past, talking to them about speaking to him alone, which was secretly just a facade as he tries to do the same actions that he did to his parents earlier to Courage. Courage is then caught by the evil vet, who then starts the countdown and then traps Courage in the rocket. When Muriel and Eustace discover his true nature, as well as attempt to rescue Courage, he decides that Muriel and Eustace "have seen too much", and that he cannot allow his operation and research to be discovered and exposed to the public. He catches Muriel and Eustace with a net, and briefly explains that "they will become the first humans to see [his] secret experiment at work", and claiming that "breeding dogs in space is the future" of normal dog breeding (with Courage opposing the crazed vet's evil space breeding scheme), before trapping them in the rocket to be sent into space to prevent them from interfering with his cruel plan. However, Courage saves his owners from the imminent launch and foils the evil vet's plans, trapping him in the rocket instead. As the countdown to the launch ends, the rocket engines ignite and the rocket itself lifts off with the vet inside, finally ending his cruelty to dogs for good. At the end of the episode, his rocket already crash landed on an unnamed planet, as he opens the door and is then petrified, finding out that all the dogs (including Courage's parents, and the same dogs seen on the milk carton's "Missing" advertisement at the beginning of the episode) have survived, which meant that his breeding experiment to see that normal dogs would breed space dogs has failed. Out of pure anger and vengeance by the dogs, the Cruel Veterinarian laughs nervously onscreen for the last time before he is dragged off in a net and brutally mauled by the vengeful dogs off-screen for his actions, presumably to death. He is heard screaming in pain during the attack. === The Empress === Voiced by Winnie Chaffee The Empress is the aunt of Di Lung, and she appeared in "Squatting Tiger, Hidden Dog", where her source of power (a magic silkworm) is dying and needs the bones of someone truly innocent to recharge it. She tries to steal Muriel's bones, but is stopped by Courage and the Empress' twin sister (who is good and is the true Empress). The Bad Empress made a cameo appearance in "Aqua Farmer". === The Great Fusilli === Voiced by Jim Cummings The Great Fusilli is an Italian alligator devoted to theater arts who turns people into puppets so that they cannot leave his show. He is defeated when he mistakes Courage for a ghost and falls off the balcony and becomes a marionette himself, but not before changing Eustace and Muriel. === The Shadow === Voiced by Dennis Predovic The Shadow is the living shadow that can change his own shape and appearance. In the episode "The Shadow of Courage", he becomes free after an cruel old miser had collapsed and passed away in his laboratory, he later terrorize the people of Nowhere by frightening them, but was forced to retreat in the Bagge estate during a lightning storm where he began scaring both Courage and Eustace. Eventually Courage decided to confront him where he reveals that he never wanted to be like the old man and wants to become a movie star, Courage then takes the Shadow to see the night sky where he can become an actual star, happy with this revelation he waved goodbye to Courage and jumped into the cosmos, turning into a new star. === The Shark === This is another monster that is also not actually antagonistic, but is seen in 'Courage in the Big Stinkin' City' as a second creature hidden behind a door inside an apartment block that Courage enters to search for a package for Schwick. === The Weremole === The Weremole is a legendary mole similar to a werewolf but much smaller, yet just as fierce. It has a taste for rabbits and people and if a person is bitten by the weremole, they become one themselves. Its bite does not affect other creatures. The only way to reverse the transformation is to feed one of the weremole's hairs to the victim. The weremole bites Muriel on the hand and when the moon is full she transforms into a weremole. Courage and Eustace team up realizing that they are in more trouble than they thought. Courage and Eustace defeat Muriel when Courage drops one of the original weremole's hairs in Muriel's mouth, and Muriel returns to normal. === The Windmill Vandals === The Windmill Vandals are a group of 4 horsebacked Vandals (Eastern Germanic Tribesmen) who once plagued the land of Nowhere. The farmer who once lived in the farmhouse where the Bagge family now reside constructed the windmill next to the farmhouse, and inscribed several runes, one on each blade of the windmill, in order to keep the Vandals away. In the episode in which they appear, the windmill breaks, and the Vandals appear as wraiths to come and destroy the farmhouse (even though there were other instances where the windmill was damaged throughout the show and the Vandals did not appear). The mill is repaired and broken several times, until finally it is fully fixed, and the Vandals banished forever more. === Violin girl === The violin girl is a third creature hidden inside Schwick's apartment where the package he orders Courage to retrieve is also situated. The girl initially has her back to Courage, but then turns and scares him with a scary face. However, she is also seen with a normal face, implying that she can terrify people when it suits her needs. === Robot Randy === Voiced by Peter Fernandez Robot Randy is an outcast from a distant planet populated by gigantic violent robots. He is sent to conquer Earth to redeem his honor. Once on the planet, he enslaves Eustace, Muriel, and Courage, forcing them to build statues of him. However, he is internally conflicted, as he does not wish to hurt others, but instead to whittle reindeer. Courage challenges Randy in a competition to save the Bagges. When Courage wins, Randy releases them and returns to his planet, where he is accepted for his carving skills. === The Evil Eggplants === The Evil Eggplants are a group of talking eggplants that live under the Bagges' farm and are led by a large, deep purple eggplant and his dumb sidekick. They spy on the farm through a periscope placed in an eggplant Muriel grows. They decide to attack the farm because they are not getting enough water and because Muriel harvests the eggplant with the periscope, angering them because they believe it is unjust to eat an eggplant. The eggplants take Muriel captive for her treatment of the eggplant, but Courage eventually saves her and floods the chasing army of eggplants, causing them to take root and leave the farm alone. This episode is the only time the eggplants make an appearance. === Eliza and Elisa Stitch === Voiced by Fran Brill Eliza and Elisa Stitch are a pair of conjoined twin sisters who attempt to be immortal by sewing other women's souls into a quilt. They did this by making them put a symbol on a piece of fabric, turning the person into quilt material, then they say a chant "Be believe belong be believe belong leave the circle never weave this quilt forever." === Mona Lisa === Mona Lisa is a woman painted by Leonardo da Vinci and is a work of art long adored by Muriel. After the Bagges are inadvertently locked inside the Louvre, an eerie alignment of the planets occurs and the exhibits come to life including Mona Lisa and The Thinker. Mona Lisa attempts to get the Thinker to kiss her, but he only thinks about it, true to his title. She ends up with another male statue after Courage hits him with Cupid's arrow and holds up her picture. She willingly went back to her painting with the male statue and let Muriel go. She only appears in the episode "So in Louvre Are We Two". === The Thinker === The Thinker is the masterpiece of Auguste Rodin who goes on a date with Mona Lisa during the episode. He is constantly saying, "Let me think." every time Mona Lisa suggests something that they should do. His thinking got in the way though, and he ended up alone in a painting after the planets were no longer aligned. He also only appears in the episode "So in Louvre Are We Two". === Conway the Contaminationist === Voiced by Peter Fernandez Conway the Contaminationist is an elderly man claiming to be 193 years old, who also claims that a filthy environment is "better" and "healthier" than a clean one ("Out with the good air, in with the bad"). He only appears in the episode of the same name, in which he pollutes the Bagge farmhouse and convinces Muriel and Eustace to be filthy as well. === Chief Wicky Wicky === Voiced by Babi Floyd Chief Wicky Wicky is the overweight leader of an island tribe, who live on Hip Hip Island, looking for someone to sacrifice to their volcano god. He lives on the island with his daughter Wicky Wicky Woo. === The Space Whale === The Space Whale is a giant whale from space who is capable of devouring planets, asteroids, ships, and comets. After it attempts to eat a pair of Star-Makers, the male squid sacrifices himself to save the female by exploding into stars that destroys them both. Like the Star-Makers, the Space Whale is the last of its kind. === Fishionary === Voiced by Gerrianne Raphael The Fishionary is a purple female fish who serves as a missionary for the Fish Judges and their octopus coworker. She comes to the farm and takes the Bagges and Courage to the Judges' domain in a bus, falsely accusing them of pulling crimes against seas creatures. == Minor characters == === Jennings === Voiced by Simon Prebble Jennings was the cruel, old, rich guy's butler in the episode "The Shadow of Courage". The episode opens with his master firing him. Jennings was annoyed by the rich man, so when he was fired, he dropped his handkerchief and walked away, uncaring. While walking away, he hears the rich guy begging for aid after dropping to the floor due to a heart attack; instead of helping, he walks away, happily humming. === Floyd === Voiced by John R. Dilworth Floyd is a balding elderly man, who deals with various paranormal activities, often making cameo appearances on the show. He's usually a good person, but he's been a villain in some episodes. === Charlie the Mouse === Voiced by Tom McKeon and John R. Dilworth ("The Mask") Charlie is a delivery mouse and a personal friend of Courage's, usually helping Courage out in certain situations. He is referred to as Mr. Mouse, with his first name revealed as Charlie in the episode "The Mask". His interaction with Courage often end with Courage exclaiming "Thanks, Mr. Mouse!", to which he replies "No prob." === Space Dino === Space Dino is a dinosaur-like alien that stands on an asteroid outside Earth's atmosphere, and is always seen with a tennis racket, which he uses to hit celestial objects. In the episode "1,000 Years of Courage", the Space Dino hits a meteor, which strikes Earth and causes time to progress 1,000 years into the future (taking Courage, Eustace, and Muriel into a new civilization of talking bananas), and later causes another meteor to strike the Earth (sending Courage and his owners back to the past). === Jean Bon === Voiced by Tom McKeon Jean Bon is a pig butcher who runs a restaurant in Nowhere with his wife Mrs. Bon. He first appeared in the episode "Heads of Beef" where Eustace and Courage visit his establishment for some burgers when Muriel was sick, however Courage suspects that he might be turning people into meat due to his burger resembling a gentleman he last seen going to the restroom. It is later revealed to be a misunderstanding as his wife was sculpting meat to resemble customers and that the gentleman (who is actually a curator of culinary wonders) and Eustace are both alive. === Noble and Hope === Noble and Hope are Courage's parents whose appearances resemble Courage's, except his father had a mustache and his mother wore a hat with a flower on top and holding a blue purse. Not much is known about his parents or even their names during the series, although Courage's father was called Henry during one of the flashbacks, as they were seen only in the episode "Remembrance of Courage Past" centring on flashbacks to his parents in the veterinarian's office, where Courage last saw his parents. They were launched into space by the Cruel Veterinarian. Courage avoided a similar fate by escaping through a garbage chute, where he was found by Muriel. The Cruel Veterinarian was trapped (by Courage, during the vet's failed attempts to send him, Muriel and Eustace into space) in the rocket, and was launched in space, crash-landing on the planet where Courage's parents and other dogs resided. In the prequel pilot Before Courage, their names were revealed to be Noble and Hope. === Kitty and Bunny === Voiced by Barbara McCulloh & Lori Ann Mahl Kitty and Bunny are a female cat and a rabbit who are best friends. They appeared in the episode "The Mask" where Bunny is held captive by her abusive boyfriend Mad Dog and Kitty tries to save her, unintentionally getting help from Courage even though he's kept in the dark about the situation and is terrified of Kitty. At the start of the episode, Kitty obscures her face with a mask and believes that all dogs are evil; as a result, she physically attacks Courage several times while staying at the Bagge house. Courage attempts to steal her favorite mouse toy in retaliation and runs away with it, but has a change of heart upon learning the truth about Kitty’s past and that the mouse was a gift from Bunny. Courage later rescues Bunny and defeats Mad Dog and his gang. Bunny gives Courage a kiss on the cheek and Kitty awaits Bunny at the Amtrak passenger train's rear, where they both reunite. Bunny tells Kitty that Courage saved her life. Kitty then admits that she had been wrong about dogs and helps Bunny onto a train she was on. The two thank Courage and ride off together. Kitty's mask was later used by Eustace to protect his face from explosions while he fixed the boiler. It was later confirmed by John R. Dilworth on his Twitter that Kitty and Bunny are now in a relationship. === Icket Bagge === Icket Bagge is Eustace's and Horst's deceased father, Ma Bagge's husband and Muriel's father-in-law. He is mentioned in the episodes "The Sandwhale Strikes" and "Mother's Day". His appearance is very close to Eustace's, except he has a beard. He apparently was very brave and big; as Ma quotes, "You [Eustace] couldn't fill his shoes!". This is no exaggeration, as his shoes were rather huge compared to his son. It is unknown how his relationship with Eustace was, whether he treated Eustace poorly like Horst and Ma or he treated Eustace with respect. === The Duck Brothers === Voiced by Will Ryan The Duck Brothers are three space ducks who are brothers. Their names are Donnie, Clyde, and Payne. One of them is always laying eggs even though he is male. They appear in two episodes, the first in which two of them abduct Muriel and place a mind-control device on her for their own purposes. Courage tries to rescue Muriel, only to find that the duck brothers were planning a rescue mission of their own (to save the other duck brother, who has been captured by the United States Government and is about to be made into dinner.) Courage volunteers to be mind-controlled instead, and they save the third brother. The three duck brothers reunite and leave. Two of the brothers make a cameo appearance in "Ball of Revenge", where they play guitars and perform as the half-time show. === The Hunchback of Nowhere === Voiced by Allen Swift The Hunchback of Nowhere is a strange and enigmatic character who has made only one appearance in the first season, in an episode of the same name. In appearance he is a short, facially-deformed little man who is hunchbacked, carrying with him a series of bells. Traveling across Nowhere in the middle of a rainy season, the Hunchback tried to find sanctuary among the locals only to be turned away by them based on his disfigured appearance. However, he is friendly and makes friends with Courage in the barn, where the Hunchback goes after being turned away by Eustace. He finally teaches Eustace that it is what is on the inside that counts. === The Sandman === Voiced by David Saire Sandman is the king of sleep who resides in a tall castle that is apparently made of sand in the middle of a forest, counting sheep indefinitely in a futile attempt to go to sleep. After stealing Muriel's "sleep" to cure his insomnia, which rendered Muriel sleepless, Courage tracked him down to retrieve it. After a prolonged chase, Courage found the Sandman's lost teddy bear under his mattress. With his beloved stuffed animal back, Sandman willingly returned Muriel's "sleep". === Basil === Voiced by George Taylor Basil is a male burglar who appears in the episode “Family Business”. Bizarrely he calls Muriel ‘Mama Mashed Potatoes’, Eustace ‘Uncle Twinkletoes’ and Courage ‘Nigel’, after the members of his family who he lived with previously. He later sends the Bagges a letter explaining he has since given up a life of crime and has become an underwater electric eel massage therapist. === The Star-Maker === The Star-Maker is a squid from space who landed on Earth with her unhatched offspring. She and her mate are the last of their kind. After her mate died saving them from a space whale, she escapes to Earth to hatch the eggs. After being found near the Bagge’s farmhouse, Eustace calls the US government, who contain the squid in a mobile laboratory. Courage manages to hatch her offspring, who return to space to make new stars. Afterwards, the Star-Maker dies peacefully and her body becomes a garden of large flowers and bushes. === The Magic Tree === Voiced by Peter Fernandez The Magic Tree is a magical tree that Courage grows, capable of making ideas and dreams come true. It can also talk. It grants wishes, whether they are good or bad, and it ends up granting a wish for Eustace which causes Muriel's head to swell up. Eustace then considers it a threat and decides to chop the tree down and Courage has to defend it for three days in order to cure Muriel. Although Eustace had a bit of sympathy, he chose to cut it down anyway despite its warnings of what will happen if he does. After the tree has been cut down and before it dies, it tells Courage how to cure Muriel. The tree had the last laugh against Eustace as the episode ended with Eustace's head swollen up just like Muriel's had been in retaliation for cutting it down. === Carmen the Serpent === Voiced by Vima Bauer Carmen the Serpent is a monstrous, one-eyed sea serpent who lives in the Evil River, who is "evil" according to a sea-captain. The sea-captain fools the Bagges under the false promise of a luxury cruise, only to reveal that he actually shanghaied them to sail through the Evil River to find and hunt down Carmen. The sea-serpent kidnaps Muriel and takes her to her cave and starts singing opera to her. Courage comes to Muriel's rescue, only to realize that Carmen was not trying to harm Muriel. Courage helps Carmen to dodge and defeat the evil captain. === Twin Raccoons === Voiced by BJ Ward (Hugo) and John R. Dilworth (Herman) Twin Raccoons are two raccoon brothers who are revealed as bandits. They attack Courage and kidnap Muriel because they wanted her as a parent. Muriel feels pity on them and accepts them like her own adopted children. At the end of the episode, Muriel's place has been taken over by Eustace as a new parent. They reappear in the episode "Farmer Hunter, Farmer Hunted" as audience members in the Hunt for Knowledge game show, however their names are "Hugo & Herman". === Horst Bagge === Voiced by Peter Fernandez Horst Bagge is Eustace's deceased older brother and Muriel's brother-in-law, who was a hunter. The cause of his death is unknown. He was the former owner of the farmhouse as seen in a flashback in the episode "Farmer Hunter, Farmer Hunted". Eustace is now the current owner presumably inheriting the farmhouse after Horst’s death. He often belittled Eustace for his low masculinity. In the episode “Shirley the Medium”, Horst leaves behind a box containing all the money he left behind. However the box is guarded by a demon to prevent anyone from obtaining the contents. === Nowhere Newsman === Voiced by Paul Schoeffler Nowhere Newsman is a local TV news reporter. The Nowhere Newsman introduces every episode stating, "We interrupt this program to bring you the Courage the Cowardly Dog show." He is also seen in some episodes when the television is on, conveying news about the antagonist. === Duncan === Duncan is the storm-goddess's pet dog who looks similar to Courage who gets lost. The storm-goddess mistakes Courage for Duncan and tries to take him, but Muriel argues with her (as such, the storm-goddess angrily destroys the farmhouse with a storm). Mr. (Charlie) Rat tells Courage where Duncan is. Courage looks for Duncan and finally finds him in a sewer licking the God-Bone, a bone that no dog can ever stop licking once licked. === The Librarian === Voiced by Gerrianne Raphael The Librarian appears only in the episode "Wrath of the Librarian". She never speaks, only whispering "Shhh" while the lion statues in front of the library speak on her behalf. She operates the library in Nowhere where she punishes anyone who doesn’t return their borrowed library books on time. === Clyde the Fog Spirit === Voiced by John R. Dilworth Clyde the Fog Spirit appears in the animated special "The Fog of Courage" who comes to the farm to get the amulet that apparently belongs to the Fog Ghost's long lost love. === Bigfoot === Voiced by John R. Dilworth Bigfoot appears only in the episode "Courage Meets Bigfoot". Although portrayed as a scary monster, in the same episode, he's actually friendly and slightly sensitive. At the end of the episode, it's revealed that his name was Theodore and he simply got lost after playing far away from home (despite being told by his mother to not wander off). === Velma Dinkley's Tablet === Voiced by Kate Micucci A hi-tech tablet that belongs to Velma Dinkley, which Scooby and Courage connect to Courage's computer to help it provide them with the information they need to rescue their friends. She and the computer both become smitten with each other during their interfacing. Her voice sounds identical to Velma. === Mystery Incorporated === Scooby-Doo: This happy-go-lucky hound avoids scary situations at all costs, but he'll do anything for a Scooby Snack! Shaggy Rogers: This laid-back dude would rather look for grub than search for clues, but he usually finds both! Fred Jones: The leader and oldest member of the gang. He's a good sport - and good at them, too! Daphne Blake: As a sixteen-year-old fashion queen, Daphne solves her mysteries in style. Velma Dinkley: Although she's the youngest member of Mystery Inc., Velma's an old pro at catching crooks. == References ==

This is a list of characters from the Cartoon Network animated series, Courage the Cowardly Dog.

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cultural anthropology

cultural anthropology (wiktionary)

Wikibooks IPA(key): /ˌkʊltʃəɹəl ˌænθɹəˈpɑlədʒi/, enPR: kŭl'chərəl ăn'thrəpŏlʹəjē cultural anthropology (uncountable) (anthropology) The field of anthropology that studies human behavior, culture, and social interaction; one of four commonly recognized fields of anthropology. social anthropology (Britain) socio-cultural anthropology linguistic anthropology physical anthropology biological anthropology archaeology

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cultural anthropology

Cultural Anthropology (journal) (wikipedia)

Cultural Anthropology is a quarterly peer-reviewed academic journal published by the American Anthropological Association on behalf of the Society for Cultural Anthropology. It was established in 1986 and covers emerging areas of anthropology. In 2014, it became open access. Since 2022, it has been edited by a collective, composed of Matilde Córdoba Azcárate, Alberto Corsín Jiménez, Julia Elyachar, Joanne Nucho, AbdouMaliq Simone, Manuel Tironi, and Ather Zia. == Abstracting and indexing == The journal is abstracted and indexed in Current Contents/Social & Behavioral Sciences, Scopus, and the Social Sciences Citation Index. According to the Journal Citation Reports, the journal has a 2013 impact factor of 1.606. == References == == External links == Official website

Cultural Anthropology is a quarterly peer-reviewed academic journal published by the American Anthropological Association on behalf of the Society for Cultural Anthropology. It was established in 1986 and covers emerging areas of anthropology. In 2014, it became open access. Since 2022, it has been edited by a collective, composed of Matilde Córdoba Azcárate, Alberto Corsín Jiménez, Julia Elyachar, Joanne Nucho, AbdouMaliq Simone, Manuel Tironi, and Ather Zia.

68

cultural anthropology

Cultural anthropology (wikipedia)

Cultural anthropology is a branch of anthropology focused on the study of cultural variation among humans. It is in contrast to social anthropology, which perceives cultural variation as a subset of a posited anthropological constant. The term sociocultural anthropology includes both cultural and social anthropology traditions. Anthropologists have pointed out that through culture, people can adapt to their environment in non-genetic ways, so people living in different environments will often have different cultures. Much of anthropological theory has originated in an appreciation of and interest in the tension between the local (particular cultures) and the global (a universal human nature, or the web of connections between people in distinct places/circumstances). Cultural anthropology has a rich methodology, including participant observation (often called fieldwork because it requires the anthropologist spending an extended period of time at the research location), interviews, and surveys. == History == Modern anthropology emerged in the 19th century alongside developments in the Western world. With these developments came a renewed interest in humankind, such as its origins, unity, and plurality. It is, however, in the 20th century that cultural anthropology shifts to having a more pluralistic view of cultures and societies. The rise of cultural anthropology took place within the context of the late 19th century, when questions regarding which cultures were "primitive" and which were "civilized" occupied the mind of not only Freud, but many others. Colonialism and its processes increasingly brought European thinkers into direct or indirect contact with "primitive others". The first generation of cultural anthropologists were interested in the relative status of various humans, some of whom had modern advanced technologies, while others lacked anything but face-to-face communication techniques and still lived a Paleolithic lifestyle. == Theoretical foundations == === The concept of culture === One of the earliest articulations of the anthropological meaning of the term "culture" came from Sir Edward Tylor: "Culture, or civilization, taken in its broad, ethnographic sense, is that complex whole which includes knowledge, belief, art, morals, law, custom, and any other capabilities and habits acquired by man as a member of society." The term "civilization" later gave way to definitions given by V. Gordon Childe, with culture forming an umbrella term and civilization becoming a particular kind of culture. According to Kay Milton, former director of anthropology research at Queens University Belfast, culture can be general or specific. This means culture can be something applied to all human beings or it can be specific to a certain group of people such as African American culture or Irish American culture. Specific cultures are structured systems which means they are organized very specifically and adding or taking away any element from that system may disrupt it. === The critique of evolutionism === Anthropology is concerned with the lives of people in different parts of the world, particularly in relation to the discourse of beliefs and practices. In addressing this question, ethnologists in the 19th century divided into two schools of thought. Some, like Grafton Elliot Smith, argued that different groups must have learned from one another somehow, however indirectly; in other words, they argued that cultural traits spread from one place to another, or "diffused". Other ethnologists argued that different groups had the capability of creating similar beliefs and practices independently. Some of those who advocated "independent invention", like Lewis Henry Morgan, additionally supposed that similarities meant that different groups had passed through the same stages of cultural evolution (See also classical social evolutionism). Morgan, in particular, acknowledged that certain forms of society and culture could not possibly have arisen before others. For example, industrial farming could not have been invented before simple farming, and metallurgy could not have developed without previous non-smelting processes involving metals (such as simple ground collection or mining). Morgan, like other 19th century social evolutionists, believed there was a more or less orderly progression from the primitive to the civilized. 20th-century anthropologists largely reject the notion that all human societies must pass through the same stages in the same order, on the grounds that such a notion does not fit the empirical facts. Some 20th-century ethnologists, like Julian Steward, have instead argued that such similarities reflected similar adaptations to similar environments. Although 19th-century ethnologists saw "diffusion" and "independent invention" as mutually exclusive and competing theories, most ethnographers quickly reached a consensus that both processes occur, and that both can plausibly account for cross-cultural similarities. But these ethnographers also pointed out the superficiality of many such similarities. They noted that even traits that spread through diffusion often were given different meanings and function from one society to another. Analyses of large human concentrations in big cities, in multidisciplinary studies by Ronald Daus, show how new methods may be applied to the understanding of man living in a global world and how it was caused by the action of extra-European nations, so highlighting the role of Ethics in modern anthropology. Accordingly, most of these anthropologists showed less interest in comparing cultures, generalizing about human nature, or discovering universal laws of cultural development, than in understanding particular cultures in those cultures' own terms. Such ethnographers and their students promoted the idea of "cultural relativism", the view that one can only understand another person's beliefs and behaviors in the context of the culture in which they live or lived. Others, such as Claude Lévi-Strauss (who was influenced both by American cultural anthropology and by French Durkheimian sociology), have argued that apparently similar patterns of development reflect fundamental similarities in the structure of human thought (see structuralism). By the mid-20th century, the number of examples of people skipping stages, such as going from hunter-gatherers to post-industrial service occupations in one generation, were so numerous that 19th-century evolutionism was effectively disproved. === Cultural relativism === Cultural relativism is a principle that was established as axiomatic in anthropological research by Franz Boas and later popularized by his students. Boas first articulated the idea in 1887: "...civilization is not something absolute, but ... is relative, and ... our ideas and conceptions are true only so far as our civilization goes." Although Boas did not coin the term, it became common among anthropologists after Boas' death in 1942, to express their synthesis of a number of ideas Boas had developed. Boas believed that the sweep of cultures, to be found in connection with any sub-species, is so vast and pervasive that there cannot be a relationship between culture and race. Cultural relativism involves specific epistemological and methodological claims. Whether or not these claims require a specific ethical stance is a matter of debate. This principle should not be confused with moral relativism. Cultural relativism was in part a response to Western ethnocentrism. Ethnocentrism may take obvious forms, in which one consciously believes that one's people's arts are the most beautiful, values the most virtuous, and beliefs the most truthful. Boas, originally trained in physics and geography, and heavily influenced by the thought of Kant, Herder, and von Humboldt, argued that one's culture may mediate and thus limit one's perceptions in less obvious ways. This understanding of culture confronts anthropologists with two problems: first, how to escape the unconscious bonds of one's own culture, which inevitably bias our perceptions of and reactions to the world, and second, how to make sense of an unfamiliar culture. The principle of cultural relativism thus forced anthropologists to develop innovative methods and heuristic strategies. Boas and his students realized that if they were to conduct scientific research in other cultures, they would need to employ methods that would help them escape the limits of their own ethnocentrism. One such method is that of ethnography. This method advocates living with people of another culture for an extended period of time to learn the local language and be enculturated, at least partially, into that culture. In this context, cultural relativism is of fundamental methodological importance, because it calls attention to the importance of the local context in understanding the meaning of particular human beliefs and activities. Thus, in 1948 Virginia Heyer wrote, "Cultural relativity, to phrase it in starkest abstraction, states the relativity of the part to the whole. The part gains its cultural significance by its place in the whole, and cannot retain its integrity in a different situation." === Theoretical approaches === === Comparison with social anthropology === The rubric cultural anthropology is generally applied to ethnographic works that are holistic in approach, are oriented to the ways in which culture affects individual experience or aim to provide a rounded view of the knowledge, customs, and institutions of a people. Social anthropology is a term applied to ethnographic works that attempt to isolate a particular system of social relations such as those that comprise domestic life, economy, law, politics, or religion, give analytical priority to the organizational bases of social life, and attend to cultural phenomena as somewhat secondary to the main issues of social scientific inquiry. Parallel with the rise of cultural anthropology in the United States, social anthropology developed as an academic discipline in Britain and in France. == Foundational thinkers == === Lewis Henry Morgan === Lewis Henry Morgan (1818–1881), a lawyer from Rochester, New York, became an advocate for and ethnological scholar of the Iroquois. His comparative analyses of religion, government, material culture, and especially kinship patterns proved to be influential contributions to the field of anthropology. Like other scholars of his day (such as Edward Tylor), Morgan argued that human societies could be classified into categories of cultural evolution on a scale of progression that ranged from savagery, to barbarism, to civilization. Generally, Morgan used technology (such as bowmaking or pottery) as an indicator of position on this scale. === Franz Boas, founder of the modern discipline === Franz Boas (1858–1942) established academic anthropology in the United States in opposition to Morgan's evolutionary perspective. His approach was empirical, skeptical of overgeneralizations, and eschewed attempts to establish universal laws. For example, Boas studied immigrant children to demonstrate that biological race was not immutable, and that human conduct and behavior resulted from nurture, rather than nature. Influenced by the German tradition, Boas argued that the world was full of distinct cultures, rather than societies whose evolution could be measured by the extent of "civilization" they had. He believed that each culture has to be studied in its particularity, and argued that cross-cultural generalizations, like those made in the natural sciences, were not possible. In doing so, he fought discrimination against immigrants, blacks, and indigenous peoples of the Americas. Many American anthropologists adopted his agenda for social reform, and theories of race continue to be popular subjects for anthropologists today. The so-called "Four Field Approach" has its origins in Boasian Anthropology, dividing the discipline in the four crucial and interrelated fields of sociocultural, biological, linguistic, and archaic anthropology (e.g. archaeology). Anthropology in the United States continues to be deeply influenced by the Boasian tradition, especially its emphasis on culture. === Kroeber, Mead, and Benedict === Boas used his positions at Columbia University and the American Museum of Natural History (AMNH) to train and develop multiple generations of students. His first generation of students included Alfred Kroeber, Robert Lowie, Edward Sapir, and Ruth Benedict, who each produced richly detailed studies of indigenous North American cultures. They provided a wealth of details used to attack the theory of a single evolutionary process. Kroeber and Sapir's focus on Native American languages helped establish linguistics as a truly general science and free it from its historical focus on Indo-European languages. The publication of Alfred Kroeber's textbook Anthropology (1923) marked a turning point in American anthropology. After three decades of amassing material, Boasians felt a growing urge to generalize. This was most obvious in the 'Culture and Personality' studies carried out by younger Boasians such as Margaret Mead and Ruth Benedict. Influenced by psychoanalytic psychologists including Sigmund Freud and Carl Jung, these authors sought to understand the way that individual personalities were shaped by the wider cultural and social forces in which they grew up. Though such works as Mead's Coming of Age in Samoa (1928) and Benedict's The Chrysanthemum and the Sword (1946) remain popular with the American public, Mead and Benedict never had the impact on the discipline of anthropology that some expected. Boas had planned for Ruth Benedict to succeed him as chair of Columbia's anthropology department, but she was sidelined in favor of Ralph Linton, and Mead was limited to her offices at the AMNH. === Wolf, Sahlins, Mintz, and political economy === In the 1950s and mid-1960s anthropology tended increasingly to model itself after the natural sciences. Some anthropologists, such as Lloyd Fallers and Clifford Geertz, focused on processes of modernization by which newly independent states could develop. Others, such as Julian Steward and Leslie White, focused on how societies evolve and fit their ecological niche—an approach popularized by Marvin Harris. Economic anthropology as influenced by Karl Polanyi and practiced by Marshall Sahlins and George Dalton challenged standard neoclassical economics to take account of cultural and social factors and employed Marxian analysis into anthropological study. In England, British Social Anthropology's paradigm began to fragment as Max Gluckman and Peter Worsley experimented with Marxism and authors such as Rodney Needham and Edmund Leach incorporated Lévi-Strauss's structuralism into their work. Structuralism also influenced a number of developments in the 1960s and 1970s, including cognitive anthropology and componential analysis. In keeping with the times, much of anthropology became politicized through the Algerian War of Independence and opposition to the Vietnam War; Marxism became an increasingly popular theoretical approach in the discipline. By the 1970s the authors of volumes such as Reinventing Anthropology worried about anthropology's relevance. Since the 1980s issues of power, such as those examined in Eric Wolf's Europe and the People Without History, have been central to the discipline. In the 1980s books like Anthropology and the Colonial Encounter pondered anthropology's ties to colonial inequality, while the immense popularity of theorists such as Antonio Gramsci and Michel Foucault moved issues of power and hegemony into the spotlight. Gender and sexuality became popular topics, as did the relationship between history and anthropology, influenced by Marshall Sahlins, who drew on Lévi-Strauss and Fernand Braudel to examine the relationship between symbolic meaning, sociocultural structure, and individual agency in the processes of historical transformation. Jean and John Comaroff produced a whole generation of anthropologists at the University of Chicago that focused on these themes. Also influential in these issues were Nietzsche, Heidegger, the critical theory of the Frankfurt School, Derrida and Lacan. === Geertz, Schneider, and interpretive anthropology === Many anthropologists reacted against the renewed emphasis on materialism and scientific modelling derived from Marx by emphasizing the importance of the concept of culture. Authors such as David Schneider, Clifford Geertz, and Marshall Sahlins developed a more fleshed-out concept of culture as a web of meaning or signification, which proved very popular within and beyond the discipline. Geertz was to state: Believing, with Max Weber, that man is an animal suspended in webs of significance he himself has spun, I take culture to be those webs, and the analysis of it to be therefore not an experimental science in search of law but an interpretive one in search of meaning. Geertz's interpretive method involved what he called "thick description". The cultural symbols of rituals, political and economic action, and of kinship, are "read" by the anthropologist as if they are a document in a foreign language. The interpretation of those symbols must be re-framed for their anthropological audience, i.e. transformed from the "experience-near" but foreign concepts of the other culture, into the "experience-distant" theoretical concepts of the anthropologist. These interpretations must then be reflected back to its originators, and its adequacy as a translation fine-tuned in a repeated way, a process called the hermeneutic circle. Geertz applied his method in a number of areas, creating programs of study that were very productive. His analysis of "religion as a cultural system" was particularly influential outside of anthropology. David Schnieder's cultural analysis of American kinship has proven equally influential. Schneider demonstrated that the American folk-cultural emphasis on "blood connections" had an undue influence on anthropological kinship theories, and that kinship is not a biological characteristic, but a cultural relationship established on very different terms in different societies. Prominent British symbolic anthropologists include Victor Turner and Mary Douglas. === The post-modern turn === In the late 1980s and 1990s authors such as James Clifford pondered ethnographic authority, in particular how and why anthropological knowledge was possible and authoritative. They were reflecting trends in research and discourse initiated by feminists in the academy, although they excused themselves from commenting specifically on those pioneering critics. Nevertheless, key aspects of feminist theory and methods became de rigueur as part of the 'post-modern moment' in anthropology: Ethnographies became more interpretative and reflexive, explicitly addressing the author's methodology; cultural, gendered, and racial positioning; and their influence on the ethnographic analysis. This was part of a more general trend of postmodernism that was popular contemporaneously. Currently anthropologists pay attention to a wide variety of issues pertaining to the contemporary world, including globalization, medicine and biotechnology, indigenous rights, virtual communities, and the anthropology of industrialized societies. === Socio-cultural anthropology subfields === == Methods == Modern cultural anthropology has its origins in, and developed in reaction to, 19th century ethnology, which involves the organized comparison of human societies. Scholars like E.B. Tylor and J.G. Frazer in England worked mostly with materials collected by others—usually missionaries, traders, explorers, or colonial officials—earning them the moniker of "arm-chair anthropologists". === Participant observation === Participant observation is one of the principal research methods of cultural anthropology. It relies on the assumption that the best way to understand a group of people is to interact with them closely over a long period of time. The method originated in the field research of social anthropologists, especially Bronislaw Malinowski in Britain, the students of Franz Boas in the United States, and in the later urban research of the Chicago School of Sociology. Historically, the group of people being studied was a small, non-Western society. However, today it may be a specific corporation, a church group, a sports team, or a small town. There are no restrictions as to what the subject of participant observation can be, as long as the group of people is studied intimately by the observing anthropologist over a long period of time. This allows the anthropologist to develop trusting relationships with the subjects of study and receive an inside perspective on the culture, which helps him or her to give a richer description when writing about the culture later. Observable details (like daily time allotment) and more hidden details (like taboo behavior) are more easily observed and interpreted over a longer period of time, and researchers can discover discrepancies between what participants say—and often believe—should happen (the formal system) and what actually does happen, or between different aspects of the formal system; in contrast, a one-time survey of people's answers to a set of questions might be quite consistent, but is less likely to show conflicts between different aspects of the social system or between conscious representations and behavior. Interactions between an ethnographer and a cultural informant must go both ways. Just as an ethnographer may be naive or curious about a culture, the members of that culture may be curious about the ethnographer. To establish connections that will eventually lead to a better understanding of the cultural context of a situation, an anthropologist must be open to becoming part of the group, and willing to develop meaningful relationships with its members. One way to do this is to find a small area of common experience between an anthropologist and their subjects, and then to expand from this common ground into the larger area of difference. Once a single connection has been established, it becomes easier to integrate into the community, and it is more likely that accurate and complete information is being shared with the anthropologist. Before participant observation can begin, an anthropologist must choose both a location and a focus of study. This focus may change once the anthropologist is actively observing the chosen group of people, but having an idea of what one wants to study before beginning fieldwork allows an anthropologist to spend time researching background information on their topic. It can also be helpful to know what previous research has been conducted in one's chosen location or on similar topics, and if the participant observation takes place in a location where the spoken language is not one the anthropologist is familiar with, they will usually also learn that language. This allows the anthropologist to become better established in the community. The lack of need for a translator makes communication more direct, and allows the anthropologist to give a richer, more contextualized representation of what they witness. In addition, participant observation often requires permits from governments and research institutions in the area of study, and always needs some form of funding. The majority of participant observation is based on conversation. This can take the form of casual, friendly dialogue, or can also be a series of more structured interviews. A combination of the two is often used, sometimes along with photography, mapping, artifact collection, and various other methods. In some cases, ethnographers also turn to structured observation, in which an anthropologist's observations are directed by a specific set of questions they are trying to answer. In the case of structured observation, an observer might be required to record the order of a series of events, or describe a certain part of the surrounding environment. While the anthropologist still makes an effort to become integrated into the group they are studying, and still participates in the events as they observe, structured observation is more directed and specific than participant observation in general. This helps to standardize the method of study when ethnographic data is being compared across several groups or is needed to fulfill a specific purpose, such as research for a governmental policy decision. One common criticism of participant observation is its lack of objectivity. Because each anthropologist has their own background and set of experiences, each individual is likely to interpret the same culture in a different way. Who the ethnographer is has a lot to do with what they will eventually write about a culture, because each researcher is influenced by their own perspective. This is considered a problem especially when anthropologists write in the ethnographic present, a present tense which makes a culture seem stuck in time, and ignores the fact that it may have interacted with other cultures or gradually evolved since the anthropologist made observations. To avoid this, past ethnographers have advocated for strict training, or for anthropologists working in teams. However, these approaches have not generally been successful, and modern ethnographers often choose to include their personal experiences and possible biases in their writing instead. Participant observation has also raised ethical questions, since an anthropologist is in control of what they report about a culture. In terms of representation, an anthropologist has greater power than their subjects of study, and this has drawn criticism of participant observation in general. Additionally, anthropologists have struggled with the effect their presence has on a culture. Simply by being present, a researcher causes changes in a culture, and anthropologists continue to question whether or not it is appropriate to influence the cultures they study, or possible to avoid having influence. === Ethnography === In the 20th century, most cultural and social anthropologists turned to the crafting of ethnographies. An ethnography is a piece of writing about a people, at a particular place and time. Typically, the anthropologist lives among people in another society for a period of time, simultaneously participating in and observing the social and cultural life of the group. Numerous other ethnographic techniques have resulted in ethnographic writing or details being preserved, as cultural anthropologists also curate materials, spend long hours in libraries, churches and schools poring over records, investigate graveyards, and decipher ancient scripts. A typical ethnography will also include information about physical geography, climate and habitat. It is meant to be a holistic piece of writing about the people in question, and today often includes the longest possible timeline of past events that the ethnographer can obtain through primary and secondary research. Bronisław Malinowski developed the ethnographic method, and Franz Boas taught it in the United States. Boas' students such as Alfred L. Kroeber, Ruth Benedict and Margaret Mead drew on his conception of culture and cultural relativism to develop cultural anthropology in the United States. Simultaneously, Malinowski and A.R. Radcliffe Brown's students were developing social anthropology in the United Kingdom. Whereas cultural anthropology focused on symbols and values, social anthropology focused on social groups and institutions. Today socio-cultural anthropologists attend to all these elements. In the early 20th century, socio-cultural anthropology developed in different forms in Europe and in the United States. European "social anthropologists" focused on observed social behaviors and on "social structure", that is, on relationships among social roles (for example, husband and wife, or parent and child) and social institutions (for example, religion, economy, and politics). American "cultural anthropologists" focused on the ways people expressed their view of themselves and their world, especially in symbolic forms, such as art and myths. These two approaches frequently converged and generally complemented one another. For example, kinship and leadership function both as symbolic systems and as social institutions. Today almost all socio-cultural anthropologists refer to the work of both sets of predecessors and have an equal interest in what people do and in what people say. === Cross-cultural comparison === One means by which anthropologists combat ethnocentrism is to engage in the process of cross-cultural comparison. It is important to test so-called "human universals" against the ethnographic record. Monogamy, for example, is frequently touted as a universal human trait, yet comparative study shows that it is not. The Human Relations Area Files, Inc. (HRAF) is a research agency based at Yale University. Since 1949, its mission has been to encourage and facilitate worldwide comparative studies of human culture, society, and behavior in the past and present. The name came from the Institute of Human Relations, an interdisciplinary program/building at Yale at the time. The Institute of Human Relations had sponsored HRAF's precursor, the Cross-Cultural Survey (see George Peter Murdock), as part of an effort to develop an integrated science of human behavior and culture. The two eHRAF databases on the Web are expanded and updated annually. eHRAF World Cultures includes materials on cultures, past and present, and covers nearly 400 cultures. The second database, eHRAF Archaeology, covers major archaeological traditions and many more sub-traditions and sites around the world. Comparison across cultures includes the industrialized (or de-industrialized) West. Cultures in the more traditional standard cross-cultural sample of small-scale societies are: === Multi-sited ethnography === Ethnography dominates socio-cultural anthropology. Nevertheless, many contemporary socio-cultural anthropologists have rejected earlier models of ethnography as treating local cultures as bounded and isolated. These anthropologists continue to concern themselves with the distinct ways people in different locales experience and understand their lives, but they often argue that one cannot understand these particular ways of life solely from a local perspective; they instead combine a focus on the local with an effort to grasp larger political, economic, and cultural frameworks that impact local lived realities. Notable proponents of this approach include Arjun Appadurai, James Clifford, George Marcus, Sidney Mintz, Michael Taussig, Eric Wolf and Ronald Daus. A growing trend in anthropological research and analysis is the use of multi-sited ethnography, discussed in George Marcus' article, "Ethnography In/Of the World System: the Emergence of Multi-Sited Ethnography". Looking at culture as embedded in macro-constructions of a global social order, multi-sited ethnography uses traditional methodology in various locations both spatially and temporally. Through this methodology, greater insight can be gained when examining the impact of world-systems on local and global communities. Also emerging in multi-sited ethnography are greater interdisciplinary approaches to fieldwork, bringing in methods from cultural studies, media studies, science and technology studies, and others. In multi-sited ethnography, research tracks a subject across spatial and temporal boundaries. For example, a multi-sited ethnography may follow a "thing", such as a particular commodity, as it is transported through the networks of global capitalism. Multi-sited ethnography may also follow ethnic groups in diaspora, stories or rumours that appear in multiple locations and in multiple time periods, metaphors that appear in multiple ethnographic locations, or the biographies of individual people or groups as they move through space and time. It may also follow conflicts that transcend boundaries. An example of multi-sited ethnography is Nancy Scheper-Hughes' work on the international black market for the trade of human organs. In this research, she follows organs as they are transferred through various legal and illegal networks of capitalism, as well as the rumours and urban legends that circulate in impoverished communities about child kidnapping and organ theft. Sociocultural anthropologists have increasingly turned their investigative eye on to "Western" culture. For example, Philippe Bourgois won the Margaret Mead Award in 1997 for In Search of Respect, a study of the entrepreneurs in a Harlem crack-den. Also growing more popular are ethnographies of professional communities, such as laboratory researchers, Wall Street investors, law firms, or information technology (IT) computer employees. == Topics == === Kinship and family === Kinship refers to the anthropological study of the ways in which humans form and maintain relationships with one another and how those relationships operate within and define social organization. Research in kinship studies often crosses over into different anthropological subfields including medical, feminist, and public anthropology. This is likely due to its fundamental concepts, as articulated by linguistic anthropologist Patrick McConvell: Kinship is the bedrock of all human societies that we know. All humans recognize fathers and mothers, sons and daughters, brothers and sisters, uncles and aunts, husbands and wives, grandparents, cousins, and often many more complex types of relationships in the terminologies that they use. That is the matrix into which human children are born in the great majority of cases, and their first words are often kinship terms.Throughout history, kinship studies have primarily focused on the topics of marriage, descent, and procreation. Anthropologists have written extensively on the variations within marriage across cultures and its legitimacy as a human institution. There are stark differences between communities in terms of marital practice and value, leaving much room for anthropological fieldwork. For instance, the Nuer of Sudan and the Brahmans of Nepal practice polygyny, where one man has several marriages to two or more women. The Nyar of India and Nyimba of Tibet and Nepal practice polyandry, where one woman is often married to two or more men. The marital practice found in most cultures, however, is monogamy, where one woman is married to one man. Anthropologists also study different marital taboos across cultures, most commonly the incest taboo of marriage within sibling and parent-child relationships. It has been found that all cultures have an incest taboo to some degree, but the taboo shifts between cultures when the marriage extends beyond the nuclear family unit. There are similar foundational differences where the act of procreation is concerned. Although anthropologists have found that biology is acknowledged in every cultural relationship to procreation, there are differences in the ways in which cultures assess the constructs of parenthood. For example, in the Nuyoo municipality of Oaxaca, Mexico, it is believed that a child can have partible maternity and partible paternity. In this case, a child would have multiple biological mothers in the case that it is born of one woman and then breastfed by another. A child would have multiple biological fathers in the case that the mother had sex with multiple men, following the commonplace belief in Nuyoo culture that pregnancy must be preceded by sex with multiple men in order have the necessary accumulation of semen. ==== Late twentieth-century shifts in interest ==== In the twenty-first century, Western ideas of kinship have evolved beyond the traditional assumptions of the nuclear family, raising anthropological questions of consanguinity, lineage, and normative marital expectation. The shift can be traced back to the 1960s, with the reassessment of kinship's basic principles offered by Edmund Leach, Rodney Neeham, David Schneider, and others. Instead of relying on narrow ideas of Western normalcy, kinship studies increasingly catered to "more ethnographic voices, human agency, intersecting power structures, and historical context". The study of kinship evolved to accommodate for the fact that it cannot be separated from its institutional roots and must pay respect to the society in which it lives, including that society's contradictions, hierarchies, and individual experiences of those within it. This shift was progressed further by the emergence of second-wave feminism in the early 1970s, which introduced ideas of marital oppression, sexual autonomy, and domestic subordination. Other themes that emerged during this time included the frequent comparisons between Eastern and Western kinship systems and the increasing amount of attention paid to anthropologists' own societies, a swift turn from the focus that had traditionally been paid to largely "foreign", non-Western communities. Kinship studies began to gain mainstream recognition in the late 1990s with the surging popularity of feminist anthropology, particularly with its work related to biological anthropology and the intersectional critique of gender relations. At this time, there was the arrival of "Third World feminism", a movement that argued kinship studies could not examine the gender relations of developing countries in isolation and must pay respect to racial and economic nuance as well. This critique became relevant, for instance, in the anthropological study of Jamaica: race and class were seen as the primary obstacles to Jamaican liberation from economic imperialism, and gender as an identity was largely ignored. Third World feminism aimed to combat this in the early twenty-first century by promoting these categories as coexisting factors. In Jamaica, marriage as an institution is often substituted for a series of partners, as poor women cannot rely on regular financial contributions in a climate of economic instability. In addition, there is a common practice of Jamaican women artificially lightening their skin tones in order to secure economic survival. These anthropological findings, according to Third World feminism, cannot see gender, racial, or class differences as separate entities, and instead must acknowledge that they interact together to produce unique individual experiences. ==== Rise of reproductive anthropology ==== Kinship studies have also experienced a rise in the interest of reproductive anthropology with the advancement of assisted reproductive technologies (ARTs), including in vitro fertilization (IVF). These advancements have led to new dimensions of anthropological research, as they challenge the Western standard of biogenetically based kinship, relatedness, and parenthood. According to anthropologists Maria C. Inhorn and Daphna Birenbaum-Carmeli, "ARTs have pluralized notions of relatedness and led to a more dynamic notion of "kinning" namely, kinship as a process, as something under construction, rather than a natural given". With this technology, questions of kinship have emerged over the difference between biological and genetic relatedness, as gestational surrogates can provide a biological environment for the embryo while the genetic ties remain with a third party. If genetic, surrogate, and adoptive maternities are involved, anthropologists have acknowledged that there can be the possibility for three "biological" mothers to a single child. With ARTs, there are also anthropological questions concerning the intersections between wealth and fertility: ARTs are generally only available to those in the highest income bracket, meaning the infertile poor are inherently devalued in the system. There have also been issues of reproductive tourism and bodily commodification, as individuals seek economic security through hormonal stimulation and egg harvesting, which are potentially harmful procedures. With IVF, specifically, there have been many questions of embryotic value and the status of life, particularly as it relates to the manufacturing of stem cells, testing, and research. Current issues in kinship studies, such as adoption, have revealed and challenged the Western cultural disposition towards the genetic, "blood" tie. Western biases against single parent homes have also been explored through similar anthropological research, uncovering that a household with a single parent experiences "greater levels of scrutiny and [is] routinely seen as the 'other' of the nuclear, patriarchal family". The power dynamics in reproduction, when explored through a comparative analysis of "conventional" and "unconventional" families, have been used to dissect the Western assumptions of child bearing and child rearing in contemporary kinship studies. ==== Critiques of kinship studies ==== Kinship, as an anthropological field of inquiry, has been heavily criticized across the discipline. One critique is that, as its inception, the framework of kinship studies was far too structured and formulaic, relying on dense language and stringent rules. Another critique, explored at length by American anthropologist David Schneider, argues that kinship has been limited by its inherent Western ethnocentrism. Schneider proposes that kinship is not a field that can be applied cross-culturally, as the theory itself relies on European assumptions of normalcy. He states in the widely circulated 1984 book A critique of the study of kinship that "[K]inship has been defined by European social scientists, and European social scientists use their own folk culture as the source of many, if not all of their ways of formulating and understanding the world about them". However, this critique has been challenged by the argument that it is linguistics, not cultural divergence, that has allowed for a European bias, and that the bias can be lifted by centering the methodology on fundamental human concepts. Polish anthropologist Anna Wierzbicka argues that "mother" and "father" are examples of such fundamental human concepts and can only be Westernized when conflated with English concepts such as "parent" and "sibling". A more recent critique of kinship studies is its solipsistic focus on privileged, Western human relations and its promotion of normative ideals of human exceptionalism. In Critical Kinship Studies, social psychologists Elizabeth Peel and Damien Riggs argue for a move beyond this human-centered framework, opting instead to explore kinship through a "posthumanist" vantage point where anthropologists focus on the intersecting relationships of human animals, non-human animals, technologies and practices. === Institutional anthropology === The role of anthropology in institutions has expanded significantly since the end of the 20th century. Much of this development can be attributed to the rise in anthropologists working outside of academia and the increasing importance of globalization in both institutions and the field of anthropology. Anthropologists can be employed by institutions such as for-profit business, nonprofit organizations, and governments. For instance, cultural anthropologists are commonly employed by the United States federal government. The two types of institutions defined in the field of anthropology are total institutions and social institutions. Total institutions are places that comprehensively coordinate the actions of people within them, and examples of total institutions include prisons, convents, and hospitals. Social institutions, on the other hand, are constructs that regulate individuals' day-to-day lives, such as kinship, religion, and economics. Anthropology of institutions may analyze labor unions, businesses ranging from small enterprises to corporations, government, medical organizations, education, prisons, and financial institutions. Nongovernmental organizations have garnered particular interest in the field of institutional anthropology because they are capable of fulfilling roles previously ignored by governments, or previously realized by families or local groups, in an attempt to mitigate social problems. The types and methods of scholarship performed in the anthropology of institutions can take a number of forms. Institutional anthropologists may study the relationship between organizations or between an organization and other parts of society. Institutional anthropology may also focus on the inner workings of an institution, such as the relationships, hierarchies and cultures formed, and the ways that these elements are transmitted and maintained, transformed, or abandoned over time. Additionally, some anthropology of institutions examines the specific design of institutions and their corresponding strength. More specifically, anthropologists may analyze specific events within an institution, perform semiotic investigations, or analyze the mechanisms by which knowledge and culture are organized and dispersed. In all manifestations of institutional anthropology, participant observation is critical to understanding the intricacies of the way an institution works and the consequences of actions taken by individuals within it. Simultaneously, anthropology of institutions extends beyond examination of the commonplace involvement of individuals in institutions to discover how and why the organizational principles evolved in the manner that they did. Common considerations taken by anthropologists in studying institutions include the physical location at which a researcher places themselves, as important interactions often take place in private, and the fact that the members of an institution are often being examined in their workplace and may not have much idle time to discuss the details of their everyday endeavors. The ability of individuals to present the workings of an institution in a particular light or frame must additionally be taken into account when using interviews and document analysis to understand an institution, as the involvement of an anthropologist may be met with distrust when information being released to the public is not directly controlled by the institution and could potentially be damaging. == See also == == References == == External links == Official website of Human Relations Area Files (HRAF) based at Yale University A Basic Guide to Cross-Cultural Research from HRAF eHRAF World Cultures eHRAF Archaeology

Cultural anthropology is a branch of anthropology focused on the study of cultural variation among humans. It is in contrast to social anthropology, which perceives cultural variation as a subset of a posited anthropological constant. The term sociocultural anthropology includes both cultural and social anthropology traditions. Anthropologists have pointed out that through culture, people can adapt to their environment in non-genetic ways, so people living in different environments will often have different cultures. Much of anthropological theory has originated in an appreciation of and interest in the tension between the local (particular cultures) and the global (a universal human nature, or the web of connections between people in distinct places/circumstances). Cultural anthropology has a rich methodology, including participant observation (often called fieldwork because it requires the anthropologist spending an extended period of time at the research location), interviews, and surveys.

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papermaker

papermaker (wiktionary)

paper +‎ maker papermaker (plural papermakers) A person or company that makes paper papermaking

70

papermaker

Papermaking (wikipedia)

Papermaking is the fabrication of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a specialized craft and a medium for artistic expression. In papermaking, a dilute suspension consisting mostly of separate cellulose fibres in water is drained through a sieve-like screen, so that a mat of randomly interwoven fibres is laid down. Water is further removed from this sheet by pressing, sometimes aided by suction or vacuum, or heating. Once dry, a generally flat, uniform and strong sheet of paper is achieved. Before the invention and current widespread adoption of automated machinery, all paper was made by hand, formed or laid one sheet at a time by specialized laborers. Even today those who make paper by hand use tools and technologies quite similar to those existing hundreds of years ago, as originally developed in China and other regions of Asia, or those further modified in Europe. Handmade paper is still appreciated for its distinctive uniqueness and the skilled craft involved in making each sheet, in contrast with the higher degree of uniformity and perfection at lower prices achieved among industrial products. == History == Hemp paper had been used in China for wrapping and padding since the eighth century BCE. Paper with legible Chinese writings on it has been dated to 8 BCE. The traditional inventor attribution is of Cai Lun, an official attached to the Imperial court during the Han dynasty (202 BCE – 220 CE), said to have invented paper about 105 CE using mulberry and other bast fibres along with fishnets, old rags, and hemp waste. Paper used as a writing medium had become widespread by the 3rd century and, by the 6th century, toilet paper was starting to be used in China as well. During the Tang dynasty (618–907 CE) paper was folded and sewn into square bags to preserve the flavour of tea, while the later Song dynasty (960–1279 CE) was the first government to issue paper-printed money. In the 8th century, papermaking spread to the Islamic world, where the process was refined, and machinery was designed for bulk manufacturing. Production began in Samarkand, Baghdad, Damascus, Cairo, Morocco, and then Muslim Spain. In Baghdad, papermaking was under the supervision of the Grand Vizier Ja'far ibn Yahya. Muslims invented a method to make a thicker sheet of paper. This innovation helped transform papermaking from an art into a major industry. The earliest use of water-powered mills in paper production, specifically the use of pulp mills for preparing the pulp for papermaking, dates back to Samarkand in the 8th century. The earliest references to paper mills also come from the medieval Islamic world, where they were first noted in the 9th century by Arabic geographers in Damascus. Traditional papermaking in Asia uses the inner bark fibers of plants. This fiber is soaked, cooked, rinsed and traditionally hand-beaten to form the paper pulp. The long fibers are layered to form strong, translucent sheets of paper. In Eastern Asia, three traditional fibers are abaca, kōzo and gampi. In the Himalayas, paper is made from the lokta plant. This paper is used for calligraphy, printing, book arts, and three-dimensional work, including origami. In other Southeast Asian countries, elephants are fed with large amount of starch food, so that their feces can be used to make paper as well. This can be found in elephant preservation camps in Myanmar, where the paper is sold to fund the organization's operations. In Europe, papermaking moulds using metallic wire were developed, and features like the watermark were well established by 1300 CE, while hemp and linen rags were the main source of pulp, cotton eventually taking over after Southern plantations made that product in large quantities. Papermaking was originally not popular in Europe due to not having many advantages over papyrus and parchment. It was not until the 15th century with the invention of the movable type of printing and its demand for paper that many paper mills entered production, and papermaking became an industry. Modern papermaking began in the early 19th century in Europe with the development of the Fourdrinier machine. This machine produces a continuous roll of paper rather than individual sheets. These machines are large. Some produce paper 150 meters in length and 10 meters wide. They can produce paper at a rate of 100 km/h. In 1844, Canadian Charles Fenerty and German Friedrich Gottlob Keller had invented the machine and associated process to make use of wood pulp in papermaking. This innovation ended the nearly 2,000-year use of pulped rags and start a new era for the production of newsprint and eventually almost all paper was made out of pulped wood. == Manual == Papermaking, regardless of the scale on which it is done, involves making a dilute suspension of fibres in water, called "furnish", and forcing this suspension to drain through a screen, to produce a mat of interwoven fibres. Water is removed from this mat of fibres using a press. The method of manual papermaking changed very little over time, despite advances in technologies. The process of manufacturing handmade paper can be generalized into five steps: Separating the useful fibre from the rest of raw materials. (e.g. cellulose from wood, cotton, etc.) Beating down the fibre into pulp Adjusting the colour, mechanical, chemical, biological, and other properties of the paper by adding special chemical premixes Screening the resulting solution Pressing and drying to get the actual paper Screening the fibre involves using a mesh made from non-corroding and inert material, such as brass, stainless steel or a synthetic fibre, which is stretched in a paper mould, a wooden frame similar to that of a window. The size of the paper is governed by the open area of the frame. The mould is then completely submerged in the furnish, then pulled, shaken and drained, forming a uniform coating on the screen. Excess water is then removed, the wet mat of fibre laid on top of a damp cloth or felt in a process called "couching". The process is repeated for the required number of sheets. This stack of wet mats is then pressed in a hydraulic press. The fairly damp fibre is then dried using a variety of methods, such as vacuum drying or simply air drying. Sometimes, the individual sheet is rolled to flatten, harden, and refine the surface. Finally, the paper is then cut to the desired shape or the standard shape (A4, letter, legal, etc.) and packed. The wooden frame is called a "deckle". The deckle leaves the edges of the paper slightly irregular and wavy, called "deckle edges", one of the indications that the paper was made by hand. Deckle-edged paper is occasionally mechanically imitated today to create the impression of old-fashioned luxury. The impressions in paper caused by the wires in the screen that run sideways are called "laid lines" and the impressions made, usually from top to bottom, by the wires holding the sideways wires together are called "chain lines". Watermarks are created by weaving a design into the wires in the mould. Handmade paper generally folds and tears more evenly along the laid lines. The International Association of Hand Papermakers and Paper Artists (IAPMA) is the world-leading association for handmade paper artists. Handmade paper is also prepared in laboratories to study papermaking and in paper mills to check the quality of the production process. The "handsheets" made according to TAPPI Standard T 205 are circular sheets 15.9 cm (6.25 in) in diameter and are tested for paper characteristics such as brightness, strength and degree of sizing. Paper made from other fibers, cotton being the most common, tends to be valued higher than wood-based paper. == Industrial == A modern paper mill is divided into several sections, roughly corresponding to the processes involved in making handmade paper. Pulp is refined and mixed in water with other additives to make a pulp slurry. The head-box of the paper machine called Fourdrinier machine distributes the slurry onto a moving continuous screen, water drains from the slurry by gravity or under vacuum, the wet paper sheet goes through presses and dries, and finally rolls into large rolls. The outcome often weighs several tons. Another type of paper machine, invented by John Dickinson in 1809, makes use of a cylinder mould that rotates while partially immersed in a vat of dilute pulp. The pulp is picked up by the wire mesh and covers the mould as it rises out of the vat. A couch roller is pressed against the mould to smooth out the pulp, and picks the wet sheet off the mould. Papermaking continues to be of concern from an environmental perspective, due to its use of harsh chemicals, its need for large amounts of water, and the resulting contamination risks, as well as the carbon sequestration lost by deforestation caused by clearcutting the trees used as the primary source of wood pulp. == Notable papermakers == While papermaking was considered a lifework, exclusive profession for most of its history, the term "notable papermakers" is often not strictly limited to those who actually make paper. Especially in the hand papermaking field there is currently an overlap of certain celebrated paper art practitioners with their other artistic pursuits, while in academia the term may be applied to those conducting research, education, or conservation of books and paper artifacts. In the industrial field it tends to overlap with science, technology and engineering, and often with management of the pulp and paper business itself. Some well-known and recognized papermakers have found fame in other fields, to the point that their papermaking background is almost forgotten. One of the most notable examples might be that of the first humans that achieved flight, the Montgolfier brothers, where many accounts barely mention the paper mill their family owned, although paper used in their balloons did play a relevant role in their success, as probably did their familiarity with this light and strong material. Key inventors include James Whatman, Henry Fourdrinier, Heinrich Voelter and Carl Daniel Ekman, among others. By the mid-19th century, making paper by hand was extinct in the United States. By 1912, fine book printer and publisher, Dard Hunter had reestablished the craft of fine hand paper making but by the 1930s the craft had lapsed in interest again. When artist Douglass Howell returned to New York City after serving in World War II, he established himself as a fine art printmaker and discovered that art paper was in short supply. During the 1940s and 1950s, Howell started reading Hunter's books on paper making, as well as he learned about hand paper making history, conducted paper making research, and learned about printed books. == See also == Amate, paper made of bark, used in pre-Columbian Central America Bookbinding Museums: Williams Paper Museum, Basel Paper Mill Stickies (papermaking) == Notes and references == 24. Longwood L.C. "Science and practice of hand made paper": (2004). 25. Westerlund L.C. "Fibre options for the sustainable development of the Australian Paper and Pulp Industry": (2004) == External links == The Harrison Elliott Collection at the Library of Congress has paper specimens, personal papers and research material relating to the history of papermaking The Center for Book and Paper Arts at Columbia College Chicago hosted an exhibition on the contemporary art of hand papermaking in 2014 The International Association of Hand Papermakers and Paper Artists (IAPMA) The Arnold Yates Paper collection at University of Maryland Libraries How to make a Carton: history of paper making in Australia, John Oxley Library blog

Papermaking is the fabrication of paper and cardboard, which are used widely for printing, writing, and packaging, among many other purposes. Today almost all paper is made using industrial machinery, while handmade paper survives as a specialized craft and a medium for artistic expression. In papermaking, a dilute suspension consisting mostly of separate cellulose fibres in water is drained through a sieve-like screen, so that a mat of randomly interwoven fibres is laid down. Water is further removed from this sheet by pressing, sometimes aided by suction or vacuum, or heating. Once dry, a generally flat, uniform and strong sheet of paper is achieved. Before the invention and current widespread adoption of automated machinery, all paper was made by hand, formed or laid one sheet at a time by specialized laborers. Even today those who make paper by hand use tools and technologies quite similar to those existing hundreds of years ago, as originally developed in China and other regions of Asia, or those further modified in Europe. Handmade paper is still appreciated for its distinctive uniqueness and the skilled craft involved in making each sheet, in contrast with the higher degree of uniformity and perfection at lower prices achieved among industrial products.

71

cd

Cd (wiktionary)

Cd (chemistry) cadmium. Cd (physics) The drag coefficient (Cd or Cx), describing a characteristic amount of aerodynamic drag caused by fluid flow.

72

cd

cd (wiktionary)

cd (metrology) Symbol for the candela, an SI unit of luminous intensity. cd (Internet slang, text messaging) Abbreviation of could. Borrowed from English CD, compact disc. IPA(key): /sedeːˀ/, [seˈd̥eˀ] or IPA(key): /seːˀdeːˀ/, [ˈseˀˌd̥eˀ] cd c (singular definite cd'en, plural indefinite cd'er) CD, compact disc [from 1983] CD player (a mashine to play compact discs) compactdisk compact disc “CD,2” in Den Danske Ordbog cd on the Danish Wikipedia.Wikipedia da Borrowed from English CD. IPA(key): /seːˈdeː/ (Belgium) IPA(key): [seːˈdeː] (Netherlands) IPA(key): [seɪˈdeɪ] Hyphenation: cd Rhymes: -eː cd m (plural cd's, diminutive cd'tje n) CD, compact disc cd-brander cd-r cd-rek cd-rom cd-speler Unadapted borrowing from English CD. IPA(key): /siˈdi/ Rhymes: -idi Syllabification: c‧d cd m inan or n or f (indeclinable) (computing, music) Alternative spelling of CD (“CD, compact disc”) cd m inan or n (indeclinable) (computing, music) Alternative spelling of CD (“CD player”) cd in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN cd in Polish dictionaries at PWN cd c Alternative letter-case form of CD cd in Svensk ordbok (SO) cd in Svenska Akademiens ordlista (SAOL)

73

cd

CD (disambiguation) (wikipedia)

A CD or compact disc is a thin plastic silvery disc for audio recordings. CD or cd may also refer to: == Science and technology == === Astronomy and cosmology === Cordoba Durchmusterung, a star catalog of the southern sky Cosmological decade or CÐ, a unit of time Type-cD galaxy, a galaxy morphology classification === Biology, ecology, and medicine === Coeliac disease, long term autoimmune disorder causing intolerance to gluten Conduct disorder, a psychological disorder Conservation Dependent or LR/cd, an IUCN category Cluster of differentiation, a protocol used for the identification of cell surface molecules on white blood cells Crohn's disease Chlordane Communicable disease === Computing === CD-ROM, compact disc technology applied for use in computer data cd (command), a command line command to change the current working directory in operating systems continuous delivery, a software development design practice continuous deployment, a software development design practice collision detection, CSMA/CD === Mathematics === cd (elliptic function), one of Jacobi's elliptic functions === Other uses in science and technology === Cadmium, symbol Cd, a chemical element Candela or cd, a unit of light intensity -CD, the North American call sign suffix for Class A low-power television stations operating with digital signals Circular dichroism, a form of spectroscopy Critical Dimension, the minimum feature size that a projection system can print in photolithography Drag coefficient or cd, a dimensionless quantity used to quantify the drag of an object in a fluid Cluster decay, a rare mode of nuclear decay == Businesses and organizations == === Government, military, and political === Canadian Forces' Decoration, by post-nominal letters Centre Democrats (Denmark), a Danish former political party Centre Democrats (Netherlands), a former political party of the Netherlands Centro Democratico, a political party in Italy Christian democracy, a political ideology Civil defense, an effort to protect the citizens of a state from military attack and natural disasters Community of Democracies, an intergovernmental organization of democracies and democratizing countries Conference on Disarmament, an international forum that negotiates multilateral arms control and disarmament agreements Corps Diplomatique, the collective body of foreign diplomats accredited to a particular country or body FBI Counterintelligence Division, the United States Federal Bureau of Investigation's division responsible for investigating espionage === Other business and organizations === Certificate of deposit, a bank account in the United States with a fixed maturity date České dráhy or ČD, a railway operator of the Czech Republic Commander of the Order of Distinction, a rank in the Jamaican Orders of Societies of Honour == Places == Central District, Seattle, a district in Seattle Democratic Republic of the Congo, by ISO 3166-1 alpha-2 country code .cd, the Internet domain of the Democratic Republic of the Congo cd., abbreviation for caddesi, street, in Turkish == Other uses == 400 (number), written CD in Roman numerals 205 (number), written CD in hexadecimal AD 400 (CD), a year of the Common Era "CD", a song by T2 (band) cd, for cord (unit) of volume of wood Geely CD, a coupe automobile made by Geely Automobile Cairo Damascus or Damascus Document, a text found among the Dead Sea Scrolls Committee Draft, a status in the International Organization for Standardization Companion dog (title), a title offered to dogs by the American Kennel Club for dog obedience Cross-dressing, the act of wearing clothing associated with the opposite sex Corendon Dutch Airlines (IATA code) Sega Mega-CD Sonic CD == See also == All pages with titles beginning with CD All pages with titles containing CD CDS (disambiguation) CeeDee (disambiguation) C&D (disambiguation)

A CD or compact disc is a thin plastic silvery disc for audio recordings. CD or cd may also refer to:

74

cd

Cd (command) (wikipedia)

The cd command, also known as chdir (change directory), is a command-line shell command used to change the current working directory in various operating systems. It can be used in shell scripts and batch files. == Implementations == The command has been implemented in operating systems such as Unix, DOS, IBM OS/2, MetaComCo TRIPOS, AmigaOS (where if a bare path is given, cd is implied), Microsoft Windows, ReactOS, and Linux. On MS-DOS, it is available in versions 2 and later. DR DOS 6.0 also includes an implementation of the cd and chdir commands. The command is also available in the open source MS-DOS emulator DOSBox and in the EFI shell. It is named chdir in HP MPE/iX. The command is analogous to the Stratus OpenVOS change_current_dir command. cd is frequently included built directly into a command-line interpreter. This is the case in most of the Unix shells (Bourne shell, tcsh, bash, etc.), cmd.exe on Microsoft Windows NT/2000+ and Windows PowerShell on Windows 7+ and COMMAND.COM on DOS/ Microsoft Windows 3.x-9x/ME. The system call that effects the command in most operating systems is chdir that is defined by POSIX. Command line shells on Windows usually use the Windows API to change the current working directory, whereas on Unix systems cd calls the chdir() POSIX C function. This means that when the command is executed, no new process is created to migrate to the other directory as is the case with other commands such as ls. Instead, the shell itself executes this command. This is because, when a new process is created, child process inherits the directory in which the parent process was created. If the cd command inherits the parent process' directory, then the objective of the command cd will never be achieved. Windows PowerShell, Microsoft's object-oriented command line shell and scripting language, executes the cd command (cmdlet) within the shell's process. However, since PowerShell is based on the .NET Framework and has a different architecture than previous shells, all of PowerShell's cmdlets like ls, rm etc. run in the shell's process. Of course, this is not true for legacy commands which still run in a separate process. == Usage == A directory is a logical section of a file system used to hold files. Directories may also contain other directories. The cd command can be used to change into a subdirectory, move back into the parent directory, move all the way back to the root directory or move to any given directory. Consider the following subsection of a Unix filesystem, which shows a user's home directory (represented as ~) with a file, text.txt, and three subdirectories. If the user's current working directory is the home directory (~), then entering the command ls followed by cd games might produce the following transcript: The user is now in the "games" directory. A similar session in DOS (though the concept of a "home directory" may not apply, depending on the specific version) would look like this: C:\> dir workreports <DIR> Wed Oct 9th 9:01 games <DIR> Tue Oct 8th 14:32 encyclopedia <DIR> Mon Oct 1st 10:05 text txt 1903 Thu Oct10th 12:43 C:\> cd games C:\games> DOS maintains separate working directories for each lettered drive, and also has the concept of a current working drive. The cd command can be used to change the working directory of the working drive or another lettered drive. Typing the drive letter as a command on its own changes the working drive, e.g. C:; alternatively, cd with the /d switch may be used to change the working drive and that drive's working directory in one step. Modern versions of Windows simulate this behaviour for backwards compatibility under CMD.EXE. Note that executing cd from the command line with no arguments has different effects in different operating systems. For example, if cd is executed without arguments in DOS, OS/2, or Windows, the current working directory is displayed (equivalent to Unix pwd). If cd is executed without arguments in Unix, the user is returned to the home directory. Executing the cd command within a script or batch file also has different effects in different operating systems. In DOS, the caller's current directory can be directly altered by the batch file's use of this command. In Unix, the caller's current directory is not altered by the script's invocation of the cd command. This is because in Unix, the script is usually executed within a subshell. == Options == === Unix, Unix-like === cd by itself or cd ~ will always put the user in their home directory. cd . will leave the user in the same directory they are currently in (i.e. the current directory won't change). This can be useful if the user's shell's internal code can't deal with the directory they are in being recreated; running cd . will place their shell in the recreated directory. cd ~username will put the user in the username's home directory. cd dir (without a /) will put the user in a subdirectory; for example, if they are in /usr, typing cd bin will put them in /usr/bin, while cd /bin puts them in /bin. cd .. will move the user up one directory. So, if they are /usr/bin/tmp, cd .. moves them to /usr/bin, while cd ../.. moves them to /usr (i.e. up two levels). The user can use this indirection to access subdirectories too. So, from /usr/bin/tmp, they can use cd ../../local to go to /usr/local cd - will switch the user to the previous directory. For example, if they are in /usr/bin/tmp, and go to /etc, they can type cd - to go back to /usr/bin/tmp. The user can use this to toggle back and forth between two directories without pushd and popd. === DOS, OS/2, Windows, ReactOS === no attributes print the full path of the current directory. -p Print the final directory stack, just like dirs. -n Entries are wrapped before they reach the edge of the screen. -v entries are printed one per line, preceded by their stack positions. cd\ (DOS and Windows only) returns to the root dir. Consequently, command cd\subdir always takes the user to the named subdirectory on the root directory, regardless of where they are located when the command is issued. == Interpreters other than an operating systems shell == In the File Transfer Protocol, the respective command is spelled CWD in the control stream, but is available as cd in most client command-line programs. Some clients also have the lcd for changing the working directory locally. The numerical computing environments MATLAB and GNU Octave include a cd function with similar functionality. The command also pertains to command-line interpreters of various other application software. == See also == Directory structure pushd and popd chroot List of command-line interpreters == References == == Further reading == Wolverton, Van (1990). MS-DOS Commands: Microsoft Quick Reference, 4th Revised edition. Microsoft Press. ISBN 978-1-55615-289-4. John Paul Mueller (2007). Windows Administration at the Command Line for Windows Vista, Windows 2003, Windows XP, and Windows 2000. John Wiley & Sons. ISBN 978-0-470-16579-9. Barrett, Daniel J. (2012). Macintosh Terminal Pocket Guide: Take Command of Your Mac. O'Reilly. ISBN 978-1-4493-2898-6. == External links == Windows XP > Command-line reference A-Z > Chdir (Cd) from Microsoft TechNet cd: change the working directory – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group

The cd command, also known as chdir (change directory), is a command-line shell command used to change the current working directory in various operating systems. It can be used in shell scripts and batch files.

75

cd

Album (Public Image Ltd album) (wikipedia)

Album (also known as Compact Disc, Cassette, or mp3 depending on the format) is the fifth studio album by the English rock band Public Image Ltd, released on 27 January 1986 by Virgin and Elektra Records. In a departure from their previous releases, John Lydon was advised by trusted music producer Bill Laswell to take on an all-star cast of session and trusted musicians, including Steve Vai, Ginger Baker, Tony Williams, and Ryuichi Sakamoto of Yellow Magic Orchestra (YMO). The resulting album gave PiL one of its highest-charting songs, "Rise". == Composition credits == Most of the songs were written by Lydon with Mark Schulz and Jebin Bruni and registered in September and October 1985, such as "Round and Round (European Cars)", "Fairweather Friend", "Fishing", "Black Rubber Bag", and "Things in Ease". "Fairweather Friend" featured originally music written by Schulz and Bruni. An unrecorded Lydon/Schulz composition "Animal" was registered too. Schulz and PIL tour bassist Bret Helm had previously registered a further (presumably non-PIL, therefore unused) composition called "Cat Rap". John Lydon: "Most of the songs on the 'Album', for instance, were written at home and put onto demonstration tapes. But I didn't think the [1984/85 touring] band were good enough or experienced enough really to, like, record the song properly. And that's why I use session people. [By using session musicians] the songs obviously changed – their shape, and not their direction". "I had a live band before recording took place and a lot of material together before going into the studio. But the band was totally inexperienced, they would have put the budget up by an incredible amount. So we decided to use session people". "I make records for myself. I want them to be completely precise. Accuracy is very important to me. Otherwise it's bad work and a waste of my time, and I really don't want to waste my time. There must be a conclusion to what you do, no vagueness. There must be a sense of completeness. Every song is an emotion and it has to succeed as that, otherwise you've failed. It's bad work. That annoys me. Bad work from anyone just annoys me. I just don't need it". Producer Bill Laswell: "When we did PiL he had put a band together in California of some kids. And I had sort of decided to make a heavy group, so I invited Tony Williams, Ginger Baker, Steve Vai, and all these people came. We fired John's band and there were many nights of really harsh arguing in bars. When the smoke cleared, we made sort of a classic record, an unusual record for the time". Ginger Baker's inclusion was coincidental, given that the NME had published an April Fools joke press release in 1981 indicating that Baker was joining the band. Originally, former Captain Beefheart drummer Robert Williams was hired to play on the album after he had successfully auditioned for the band and started rehearsing with them, only to be informed a short while later that the whole band was fired and the album would be recorded with hired session musicians. == Artwork and packaging == The album's artwork was deliberately generic, with each release being named after its format. The original LP and 7" labels simply read "Label". The packaging concept was a pastiche of the generic brand products manufactured in the early 1980s; it was visually similar to those sold at the Ralphs supermarket chain (dark-blue lettering and light blue stripe over white ground) in the USA. In 1982, Flipper, a punk rock band from San Francisco, California, had released an album with the same concept and a near-identical name, Album – Generic Flipper, a pastiche of generic products manufactured for Lucky Stores supermarket chain (black lettering over yellow ground). Later in 1986, Flipper retaliated by releasing a live album titled Public Flipper Limited Live 1980–1985. The packaging concept was used on several other releases by the band from this period. The 7" single of "Rise" was called "Single" whilst the 12" single was called "12-inch Single". The music video had the title card "Video", and a 1986 compilation of music videos by the band was titled Videos. Each release used the same basic design as the LP, CD and cassette covers, although second single "Home" was issued under its own name. A 1990 boxed set of Public Image Limited albums was called Box, and a 2010 deluxe reissue of the album included "Poster" – an art print – and a making-of book titled "Book". The 2012 CD remaster of the album is titled Album. There is also a Public Image Ltd. tribute album whose cover is designed in homage to the album cover style, titled Tribute. == Recording sessions == The album was recorded in late 1985 in New York. Ginger Baker's and Tony Williams' drums were recorded at Power Station by engineer Jason Corsaro. Steve Vai's lead guitar parts were recorded at Electric Lady Studios and the rest of the album at RPM Studios and Quad Recording Studios, all engineered by Robert Musso. The recording took three weeks, followed by one week of mixing the album at The Power Station. In the liner notes of PiL's Plastic Box compilation (1999), Lydon remarked that Album was "almost like a solo album" since he was working on his own with several musicians. He said that Miles Davis came into the studio while the album was being recorded and commented that Lydon sang like Davis played the trumpet. Lydon said it was "still the best thing anyone's ever said to me." It was revealed in the liner notes to the super deluxe edition that it was actually Ornette Coleman, not Davis, who said that. Lead guitarist Steve Vai: "Bill Laswell, the producer, called and I flew in and out of New York from Alcatrazz shows to cut the parts. I did basically all the guitar parts in two days. Bill Laswell took a very interesting approach to the production of this disc. Some of the material I'd never heard and just went in and started playing on it. At the end, Johnny Lydon came in and liked it [...] There was the consideration of putting a band together – him, myself, Bill Laswell on bass and Ginger Baker on drums. Would have been quite a band". "I went in a day and did everything, then I flew back out on tour. And then I went in for another half-day, and Lydon came in on the second day. He's just like ultracool and it's the first time he's heard any of my parts and he goes 'This is fucking great, man, how did you fucking know I wanted it like that?' [...] We were thinking about turning it into a band – me, him, Bill Laswell and Ginger Baker, but well, I was doing some other things, you know? It would have been cool. To this day that's one of the projects I'm most proud of". "John Lydon came in when I was done, they were playing a track back, and he made a grimace and said 'Fookin' great man!' in that way of his. So that was funny. I'd obviously done okay". Roger Trilling (Bill Laswell's manager): "I wasn't there, but apparently Ginger played for Bill in his barn. Just solo with the horses there, apparently the trees swayed and the flowers cried. The drum god would return. One small step for Ginger, one giant leap for John Lydon. The rest of the cast was quickly assembled – Tony Williams, Steve Vai, Bernie [Worrell], Nicky [Skopelitis], Aïyb [Dieng]. First we recorded the drums, with Jason Corsaro in the Power Station and its huge concrete resounding garage. Then we moved over to Quad for bass, keyboards and rhythm guitar. I would give John bulletins as we drank beer in bars – 'Today Steve Turre blew into conch shells, tomorrow a didgeridoo. Oh, Sakamoto did great today!' John grew wary, restive, even aggravated. Howard Thompson, in charge for Elektra, was even more importunate, I remember at one point physically barring him from getting into the elevator. We recorded a few days of Vai at Electric Lady, and then moved over to RPM for three days of vocals. John, I think, got a cassette the evening before. The idea was to get him on the initial take, and if it didn't work, keep the tapes, which was Bill's music anyway. Well, John's declamations were eloquent ones and no less aggressive or irritating than the music. Everyone was pleased, and though I remember John's presence in the anteroom during the mix, what I mostly remember is an all-night Korean restaurant, where we would start drinking at three, four, or five in the morning." == Track listing == Listed on the LP sleeve as "Ingredients" "Home" reached number seventy five on the UK Singles Chart. Steve Vai contributed his guitar work to the track. == Personnel == Public Image Ltd John Lydon – lead vocals with: Bill Laswell – bass (1-6), producer Steve Vai – guitar (1-7) Nicky Skopelitis – guitar (1-4, 6) Ryuichi Sakamoto – Fairlight CMI (2, 3, 5, 7) Bernie Worrell – organ (1, 4, 6), Yamaha DX7 (3) Ginger Baker – drums (3-5, 7) Tony Williams – drums (1, 2, 6) Bernard Fowler – backing vocals (1-7) Jonas Hellborg – bass (4) Additional personnel Shankar – electric violin on 2, 4 Malachi Favors – acoustic bass on 3, 5, 7 Steve Turre – didgeridoo on 7 Aïyb Dieng – chatan pot drums on 4 == Charts == == References == == External links == Album at Discogs (list of releases)

Album (also known as Compact Disc, Cassette, or mp3 depending on the format) is the fifth studio album by the English rock band Public Image Ltd, released on 27 January 1986 by Virgin and Elektra Records. In a departure from their previous releases, John Lydon was advised by trusted music producer Bill Laswell to take on an all-star cast of session and trusted musicians, including Steve Vai, Ginger Baker, Tony Williams, and Ryuichi Sakamoto of Yellow Magic Orchestra (YMO). The resulting album gave PiL one of its highest-charting songs, "Rise".

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C (New York City Subway service) (wikipedia)

The C Eighth Avenue Local is a 19-mile-long (31 km): 1 rapid transit service in the B Division of the New York City Subway. Its route emblem, or "bullet", is blue since it is a part of the IND Eighth Avenue Line in Manhattan. The C operates at all times except late nights between 168th Street in Washington Heights, Manhattan, and Euclid Avenue in East New York, Brooklyn, making all stops in-between. During late night hours, the A train, which runs express along the entire C route during daytime hours, makes all stops. Historically, most C service ran only during rush hours, along the IND Concourse Line to Bedford Park Boulevard in the Bronx and later along the IND Rockaway Line to Rockaway Park–Beach 116th Street in Queens. Prior to 1985, the local C service was referred to as the CC, with the C designation reserved for a complementary express service that was discontinued in 1949. The CC was once the only route to serve the Bronx, Manhattan, Brooklyn, and Queens in a single trip. Outside of rush hour, local service in Manhattan was usually provided by the AA, later relabeled K, which ran between 168th Street and Chambers Street/World Trade Center. In 1988, the K and C were consolidated into one service, and during the 1990s, the C's routing was altered to create the current service pattern. A 2015 study of the route found that the C had a daily ridership of 250,000.: 1 == History == === Original IND service === The AA and CC services were the predecessors to the current C service. A and AA service began on September 10, 1932, with the opening of the first line of the Independent Subway System (IND), the Eighth Avenue Line. The IND used single letters to refer to express services and double letters for local services. The A ran express and the AA ran local from 168th Street to Chambers Street/World Trade Center, known at the time as Hudson Terminal. The AA ran at all times, and it was extended to 207th Street during nights and on Sundays when the A did not run. On February 1, 1933, the AA was extended to the newly-opened Jay Street–Borough Hall station when the A did not run, continuing to terminate at Chambers Street when the A did run. The C and CC services began operation on July 1, 1933, when the IND Concourse Line opened. The CC provided local service between Bedford Park Boulevard and Hudson Terminal during rush hours, and was extended to 205th Street during non-rush hours. It replaced the AA as Eighth Avenue Local. The C ran express, from 205th Street to Bergen Street in Brooklyn during rush hours, running express on the Concourse Line in the peak direction. C trains left Bergen Street between 3:30 p.m. and 6:50 p.m., and left 205th Street between 6:33 a.m. and 11:26 a.m. C trains ran every 4 minutes during rush hours in the peak direction, and every 5 minutes in the reverse-peak direction, and ran with 6- and 7-car trains. During morning rush hours, CC trains operated to 205th Street until 7:30 a.m., and to Tremont Avenue between 7:30 a.m. and 11:30 a.m.. PM rush hour CC trains terminated at Bedford Park Boulevard, and several other trains terminated and originated at Bedford Park Boulevard. CC trains ran every 4 minutes during rush hours, 5 minutes during middays, every 5 and 6 trains during evenings, and every 12 minutes overnight. Trains ran with 5 cars during rush hours, and with 3 cars other times. On August 17, 1933, CC trains stopped terminating at Tremont Avenue. Beginning August 19, 1933, C service was cut back from Bergen Street, but started operating during non-rush hours. At the same time, CC service was cut back from 205th Street during non-rush hours. On January 1, 1936, C service was extended to Jay Street–Borough Hall. On April 9, 1936, C service was extended to Hoyt–Schermerhorn Streets. After July 1, 1937, a few C trains continued to run to Bergen Street southbound in the morning rush hour and northbound in the evening rush hour. Also on the same date, weekend C service was discontinued, and CC service was extended to 205th Street to compensate. === IND Sixth Avenue Line opens === On December 15, 1940, the IND Sixth Avenue Line opened. Two new services, the BB (later B) and D, began running. These lines ran on the Eighth Avenue Line in upper Manhattan, switching to the Sixth Avenue Line in Midtown. The BB ran local to 168th Street during rush hours. The D joined the C as the peak direction Concourse Express. CC trains now ran between Hudson Terminal and Bedford Park during rush hours and on Saturdays and during other times, the D made local stops in the Bronx, replacing CC service. On the same date, limited morning rush hour service began between 205th Street, Bronx and Utica Avenue, Brooklyn, making local stops on the IND Fulton Street Line. AA service was reinstated during this time, but only during off-peak hours (non-rush hours, late Saturday afternoons and Sundays) when the BB and CC did not operate. The CC would provide Eighth Avenue Line local service during rush hours, with the AA replacing it during off-peak hours, mostly unchanged until 1988. In the 1940s, C trains ran every 10 minutes during rush hour, CC trains ran every 4 minutes, and D trains ran every 5 minutes. On October 24, 1949, C express service was discontinued. Additional D service was added to offset this loss. The CC, which only ran during rush hours, began terminating at Broadway–Lafayette Street Mondays to Fridays, and on Saturdays CC service continued to operate to Hudson Terminal. On December 29, 1951, Saturday CC service was discontinued. Weekday CC service returned to its previous terminal at Hudson Terminal on October 30, 1954. On August 30, 1976, the CC train replaced the E train as the rush-hour local along the IND Fulton Street Line and IND Rockaway Line, running from Rockaway Park–Beach 116th Street in Queens through Brooklyn and Manhattan to Bedford Park Boulevard in the Bronx, making it the only service to run through all four boroughs served by the subway. The Rockaway Park Shuttle HH was renamed CC. This shuttle ran between Broad Channel and Rockaway Park during off-peak hours, except late nights. With this, all daytime service to and from Rockaway Park was named CC. Late nights, the shuttle ran between Euclid Avenue, Rockaway Park and Far Rockaway–Mott Avenue via Hammels Wye, and was labeled A. On August 28, 1977, late night AA service was eliminated. The A began making local stops in Manhattan during late nights, when the AA was not running. On May 6, 1985, the IND practice of using double letters to indicate local service was discontinued. The AA was renamed the K and rush hour CC service was renamed C. The off-peak Rockaway Park Shuttle was renamed H. This change was not officially reflected in schedules until May 24, 1987. === Modern service consolidations === On December 10, 1988, the K designation was discontinued and merged into the C, which now ran at all times except late nights.: 17 The C ran from Bedford Park Boulevard to Rockaway Park during rush hours, 145th Street to Euclid Avenue during middays, and from 145th Street to World Trade Center during evenings and weekends. The A now ran express in Brooklyn during middays, and the B was extended to 168th Street during middays and early evenings. On October 23, 1992, rush hour C service was cut back from Rockaway Park–Beach 116th Street to Euclid Avenue. The 1992 change introduced five A trips in each direction run from 59th Street–Columbus Circle to Rockaway Park during rush hours, with the Rockaway Park Shuttle (renamed from H to S) operating between Broad Channel and Rockaway Park at all times. On May 29, 1994, weekend service between 7 a.m. and 11 p.m. was extended to Washington Heights–168th Street (effectively recreating the old AA) to allow A trains to run express. Beginning April 30, 1995, C service was extended to 168th Street during middays as construction on the Manhattan Bridge cut B service from Manhattan. On November 11, 1995, midday service was cut back to 145th Street after B service to 168th Street was restored. The B and the C, which both ran local along Central Park West, switched northern terminals on March 1, 1998, ending the connection between the C and the Bronx. Instead of alternating between three different terminals depending on the time of day, all C service now terminated at 168th Street. The change was made to reduce crowding on the C and to reduce passenger confusion about the C's route. Starting on May 2, 1999, C trains were extended to Euclid Avenue on evenings and weekends. The 1999 change had the C run local in Brooklyn and Manhattan and the A run express at all times except late nights. In the wake of the September 11, 2001, attacks, World Trade Center station was temporarily not usable as a terminal for the E. C service was suspended until September 24. Local service along Central Park West was replaced by the A and D, and the E was extended from Canal Street to Euclid Avenue replacing C service in Brooklyn. On January 23, 2005, a fire at the Chambers Street signal room crippled A and C service. C service was suspended until February 2 and was replaced by the A, B, D, E, and V along different parts of its route. Initial assessments suggested that it would take several years to restore normal service, but the damaged equipment was replaced with available spare parts, allowing normal service to resume on April 21. From March 29, 2020, to April 29, 2020, C trains were suspended due to the COVID-19 pandemic in New York City, and A trains to Lefferts Boulevard ran local in their place. The cutbacks meant that wait times during rush hours increased from 8 to 12 minutes. In March 2021, TWU 100, the union for subway workers, sued the MTA in order to prevent the reduced frequencies from being permanent. That same month, the MTA decided to bring back full C service; full service was restored in mid-2021. == Maintenance and rider issues == === Criticism === In August 2012, the Straphangers Campaign rated the C train the worst of the city's subway services for the fourth straight year. No other service has ranked worst for more than three years in a row. The group found that the C performed worst in three of the six categories in its annual State of the Subways Report Card: amount of scheduled service, interior cleanliness, and breakdown rate. It also ranked next-to-worst in car announcement quality, after the 7, but performed above average in regularity of service and crowding. The New York Times called the C the "least loved of New York City subway lines", citing its fleet of R32s, which were almost 50 years old at the time the Times reported on the issue. The New York Times has also stated that the C train "rattled and clanked along the deteriorating maze of tracks beneath the city, tin-clad markers of years of neglect." In 2017, the Times referred to the R32s on the C as the world's oldest subway cars "in continuous daily operation". The R32s were initially retired in late April 2020, but were temporarily pressed back into service from July through October 2020 and finally retired in early January 2022. === Improvements === In 2011, problems with the R32s were at a peak as the fleet's failure rate was rising steadily. In 2012, money was directed to replace the R32 with the R179. Bombardier Transportation won the $600 million contract to build 300 new cars. The R179s were expected to replace the R32s with some being allocated to the C. However, delivery of the R179s was delayed until 2017 and the R32s momentarily remained in service after the order was completed, so stopgap measures were implemented. In the 2010s, all trains on the C were only 480 feet (146 m) long, partially due to lower ridership levels on the route, according to NYC Transit's Rapid Transit Loading Guideline. This contrasted with trains on the rest of the mainline B Division (except for the Eastern Division and the G train), which are 600 feet (183 m) long. During summer 2010, some 600-foot-long R44 trains ran on the C, displacing some R32s, whose air conditioning units were repaired. In the summers of 2011 and 2012, some 600-foot-long R46 trains were used on the C, while the R32s were used on the A, which had significant outdoor sections where the air conditioning units did not have to be used. In the summers of 2013 and 2014 as well as from May 2015 to February 2019, some 480-foot-long R160As ran on the C, covering half of its fleet, because of the R32s' continuously aging air compressors caused by the entirely underground C route. Concurrently, some R32s in exchange were transferred to East New York Yard, where they were used on the mostly outdoor J/Z. In late 2017, after several failed proposals to permanently lengthen C trains as ridership increased, some 600-foot-long R46 trains were reassigned to the C, displacing some more R32s to the A. On November 6, 2018, some 480-foot-long R179 trains started running on the C, gradually displacing the R160As back to East New York Yard by February 6, 2019. The R179s periodically experienced major mechanical and technical issues, forcing the MTA to remove them from service. The R211 fleet, which is being delivered as of 2023, is also expected to run on the C; two 600-foot-long R211T trains with open gangways began running on the C in February 2024. Service frequencies on the C were increased after the New York state government provided funding for the changes in mid-2023. On August 7 of that year, midday service was increased to run every eight minutes instead of every ten minutes. There was supposed to be another service increase during the evening starting in December 2023, but as of February 2024, this service increase has not happened. == Route == === Service pattern === The following table shows the lines used by the C: === Stations === For a more detailed station listing, see the articles on the lines listed above. == Notes == == References == == External links == MTA NYC Transit – C Eighth Avenue Local MTA Subway Time—C Train "C Subway Timetable, Effective December 17, 2023". Metropolitan Transportation Authority. Retrieved June 28, 2024. MTA NYC Transit – A C Line Review Main Document

The C Eighth Avenue Local is a 19-mile-long (31 km): 1 rapid transit service in the B Division of the New York City Subway. Its route emblem, or "bullet", is blue since it is a part of the IND Eighth Avenue Line in Manhattan. The C operates at all times except late nights between 168th Street in Washington Heights, Manhattan, and Euclid Avenue in East New York, Brooklyn, making all stops in-between. During late night hours, the A train, which runs express along the entire C route during daytime hours, makes all stops. Historically, most C service ran only during rush hours, along the IND Concourse Line to Bedford Park Boulevard in the Bronx and later along the IND Rockaway Line to Rockaway Park–Beach 116th Street in Queens. Prior to 1985, the local C service was referred to as the CC, with the C designation reserved for a complementary express service that was discontinued in 1949. The CC was once the only route to serve the Bronx, Manhattan, Brooklyn, and Queens in a single trip. Outside of rush hour, local service in Manhattan was usually provided by the AA, later relabeled K, which ran between 168th Street and Chambers Street/World Trade Center. In 1988, the K and C were consolidated into one service, and during the 1990s, the C's routing was altered to create the current service pattern. A 2015 study of the route found that the C had a daily ridership of 250,000.: 1

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Cadmium (wikipedia)

Cadmium is a chemical element; it has symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange, and yellow pigments, to color glass, and to stabilize plastic. Cadmium use is generally decreasing because it is toxic (it is specifically listed in the European Restriction of Hazardous Substances Directive) and nickel–cadmium batteries have been replaced with nickel–metal hydride and lithium-ion batteries. Due to it being a neutron poison, cadmium is also used as a component of control rods in nuclear fission reactors. One of its few new uses is in cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms. == Characteristics == === Physical properties === Cadmium is a soft, malleable, ductile, silvery-white divalent metal. It is similar in many respects to zinc but forms complex compounds. Unlike most other metals, cadmium is resistant to corrosion and is used as a protective plate on other metals. As a bulk metal, cadmium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes. === Chemical properties === Although cadmium usually has an oxidation state of +2, it also exists in the +1 state. Cadmium and its congeners are not always considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. Cadmium burns in air to form brown amorphous cadmium oxide (CdO); the crystalline form of this compound is a dark red which changes color when heated, similar to zinc oxide. Hydrochloric acid, sulfuric acid, and nitric acid dissolve cadmium by forming cadmium chloride (CdCl2), cadmium sulfate (CdSO4), or cadmium nitrate (Cd(NO3)2). The oxidation state +1 can be produced by dissolving cadmium in a mixture of cadmium chloride and aluminium chloride, forming the Cd22+ cation, which is similar to the Hg22+ cation in mercury(I) chloride. Cd + CdCl2 + 2 AlCl3 → Cd2(AlCl4)2 The structures of many cadmium complexes with nucleobases, amino acids, and vitamins have been determined. === Isotopes === Naturally occurring cadmium is composed of eight isotopes. Two of them are radioactive, and three are expected to decay but have not measurably done so under laboratory conditions. The two natural radioactive isotopes are 113Cd (beta decay, half-life is 7.7×1015 y) and 116Cd (two-neutrino double beta decay, half-life is 2.9×1019 y). The other three are 106Cd, 108Cd (both double electron capture), and 114Cd (double beta decay); only lower limits on these half-lives have been determined. At least three isotopes – 110Cd, 111Cd, and 112Cd – are stable. Among the isotopes that do not occur naturally, the most long-lived are 109Cd with a half-life of 462.6 days, and 115Cd with a half-life of 53.46 hours. All of the remaining radioactive isotopes have half-lives of less than 2.5 hours, and the majority have half-lives of less than 5 minutes. Cadmium has 8 known meta states, with the most stable being 113mCd (t1⁄2 = 14.1 years), 115mCd (t1⁄2 = 44.6 days), and 117mCd (t1⁄2 = 3.36 hours). The known isotopes of cadmium range in atomic mass from 94.950 u (95Cd) to 131.946 u (132Cd). For isotopes lighter than 112 u, the primary decay mode is electron capture and the dominant decay product is element 47 (silver). Heavier isotopes decay mostly through beta emission producing element 49 (indium). One isotope of cadmium, 113Cd, absorbs neutrons with high selectivity: With very high probability, neutrons with energy below the cadmium cut-off will be absorbed; those higher than the cut-off will be transmitted. The cadmium cut-off is about 0.5 eV, and neutrons below that level are deemed slow neutrons, distinct from intermediate and fast neutrons. Cadmium is created via the s-process in low- to medium-mass stars with masses of 0.6 to 10 solar masses, over thousands of years. In that process, a silver atom captures a neutron and then undergoes beta decay. == History == Cadmium (Latin cadmia, Greek καδμεία meaning "calamine", a cadmium-bearing mixture of minerals that was named after the Greek mythological character Κάδμος, Cadmus, the founder of Thebes) was discovered in contaminated zinc compounds sold in pharmacies in Germany in 1817 by Friedrich Stromeyer. Karl Samuel Leberecht Hermann simultaneously investigated the discoloration in zinc oxide and found an impurity, first suspected to be arsenic, because of the yellow precipitate with hydrogen sulfide. Additionally Stromeyer discovered that one supplier sold zinc carbonate instead of zinc oxide. Stromeyer found the new element as an impurity in zinc carbonate (calamine), and, for 100 years, Germany remained the only important producer of the metal. The metal was named after the Latin word for calamine, because it was found in this zinc ore. Stromeyer noted that some impure samples of calamine changed color when heated but pure calamine did not. He was persistent in studying these results and eventually isolated cadmium metal by roasting and reducing the sulfide. The potential for cadmium yellow as pigment was recognized in the 1840s, but the lack of cadmium limited this application. Even though cadmium and its compounds are toxic in certain forms and concentrations, the British Pharmaceutical Codex from 1907 states that cadmium iodide was used as a medication to treat "enlarged joints, scrofulous glands, and chilblains". In 1907, the International Astronomical Union defined the international ångström in terms of a red cadmium spectral line (1 wavelength = 6438.46963 Å). This was adopted by the 7th General Conference on Weights and Measures in 1927. In 1960, the definitions of both the metre and ångström were changed to use krypton. After the industrial scale production of cadmium started in the 1930s and 1940s, the major application of cadmium was the coating of iron and steel to prevent corrosion; in 1944, 62% and in 1956, 59% of the cadmium in the United States was used for plating. In 1956, 24% of the cadmium in the United States was used for a second application in red, orange and yellow pigments from sulfides and selenides of cadmium. The stabilizing effect of cadmium chemicals like the carboxylates cadmium laurate and cadmium stearate on PVC led to an increased use of those compounds in the 1970s and 1980s. The demand for cadmium in pigments, coatings, stabilizers, and alloys declined as a result of environmental and health regulations in the 1980s and 1990s; in 2006, only 7% of total cadmium consumption was used for plating, and only 10% was used for pigments. At the same time, these decreases in consumption were compensated by a growing demand for cadmium for nickel–cadmium batteries, which accounted for 81% of the cadmium consumption in the United States in 2006. == Occurrence == Cadmium makes up about 0.1 ppm of Earth's crust and is the 65th most abundant element. It is much rarer than zinc, which makes up about 65 ppm. No significant deposits of cadmium-containing ores are known. The only cadmium mineral of importance, greenockite (CdS), is nearly always associated with sphalerite (ZnS). This association is caused by geochemical similarity between zinc and cadmium, with no geological process likely to separate them. Thus, cadmium is produced mainly as a byproduct of mining, smelting, and refining sulfidic ores of zinc, and, to a lesser degree, lead and copper. Small amounts of cadmium, about 10% of consumption, are produced from secondary sources, mainly from dust generated by recycling iron and steel scrap. Production in the United States began in 1907, but wide use began after World War I. Metallic cadmium can be found in the Vilyuy River basin in Siberia. Rocks mined for phosphate fertilizers contain varying amounts of cadmium, resulting in a cadmium concentration of as much as 300 mg/kg in the fertilizers and a high cadmium content in agricultural soils. Coal can contain significant amounts of cadmium, which ends up mostly in coal fly ash. Cadmium in soil can be absorbed by crops such as rice and cocoa. In 2002, the Chinese ministry of agriculture measured that 28% of rice it sampled had excess lead and 10% had excess cadmium above limits defined by law. Consumer Reports tested 28 brands of dark chocolate sold in the United States in 2022, and found cadmium in all of them, with 13 exceeding the California Maximum Allowable Dose level. Some plants such as willow trees and poplars have been found to clean both lead and cadmium from soil. Typical background concentrations of cadmium do not exceed 5 ng/m3 in the atmosphere; 2 mg/kg in soil; 1 μg/L in freshwater and 50 ng/L in seawater. Concentrations of cadmium above 10 μg/L may be stable in water having low total solute concentrations and p H and can be difficult to remove by conventional water treatment processes. == Production == Cadmium is a common impurity in zinc ores, and it is most often isolated during the production of zinc. Some zinc ores concentrates from zinc sulfate ores contain up to 1.4% of cadmium. In the 1970s, the output of cadmium was 2.9 kilograms (6.5 lb) per ton of zinc. Zinc sulfide ores are roasted in the presence of oxygen, converting the zinc sulfide to the oxide. Zinc metal is produced either by smelting the oxide with carbon or by electrolysis in sulfuric acid. Cadmium is isolated from the zinc metal by vacuum distillation if the zinc is smelted, or cadmium sulfate is precipitated from the electrolysis solution. The British Geological Survey reports that in 2001, China was the top producer of cadmium with almost one-sixth of the world's production, closely followed by South Korea and Japan. == Applications == Cadmium is a common component of electric batteries, pigments, coatings, and electroplating. === Batteries === In 2009, 86% of cadmium was used in batteries, predominantly in rechargeable nickel–cadmium batteries. Nickel–cadmium cells have a nominal cell potential of 1.2 V. The cell consists of a positive nickel hydroxide electrode and a negative cadmium electrode plate separated by an alkaline electrolyte (potassium hydroxide). The European Union put a limit on cadmium in electronics in 2004 of 0.01%, with some exceptions, and in 2006 reduced the limit on cadmium content to 0.002%. Another type of battery based on cadmium is the silver–cadmium battery. === Electroplating === Cadmium electroplating, consuming 6% of the global production, is used in the aircraft industry to reduce corrosion of steel components. This coating is passivated by chromate salts. A limitation of cadmium plating is hydrogen embrittlement of high-strength steels from the electroplating process. Therefore, steel parts heat-treated to tensile strength above 1300 MPa (200 ksi) should be coated by an alternative method (such as special low-embrittlement cadmium electroplating processes or physical vapor deposition). Titanium embrittlement from cadmium-plated tool residues resulted in banishment of those tools (and the implementation of routine tool testing to detect cadmium contamination) in the A-12/SR-71, U-2, and subsequent aircraft programs that use titanium. === Nuclear fission === Cadmium is used in the control rods of nuclear reactors, acting as a very effective neutron poison to control neutron flux in nuclear fission. When cadmium rods are inserted in the core of a nuclear reactor, cadmium absorbs neutrons, preventing them from creating additional fission events, thus controlling the amount of reactivity. The pressurized water reactor designed by Westinghouse Electric Company uses an alloy consisting of 80% silver, 15% indium, and 5% cadmium. === Televisions === QLED TVs have been starting to include cadmium in construction. Some companies have been looking to reduce the environmental impact of human exposure and pollution of the material in televisions during production. === Anticancer drugs === Complexes based on cadmium and other heavy metals have potential for the treatment of cancer, but their use is often limited due to toxic side effects. === Compounds === Cadmium oxide was used in black and white television phosphors and in the blue and green phosphors of color television cathode ray tubes. Cadmium sulfide (CdS) is used as a photoconductive surface coating for photocopier drums. Various cadmium salts are used in paint pigments, with CdS as a yellow pigment being the most common. Cadmium selenide is a red pigment, commonly called cadmium red. To painters who work with the pigment, cadmium provides the most brilliant and durable yellows, oranges, and reds – so much so that during production, these colors are significantly toned down before they are ground with oils and binders or blended into watercolors, gouaches, acrylics, and other paint and pigment formulations. Because these pigments are potentially toxic, users should use a barrier cream on the hands to prevent absorption through the skin even though the amount of cadmium absorbed into the body through the skin is reported to be less than 1%. In PVC, cadmium was used as heat, light, and weathering stabilizers. Currently, cadmium stabilizers have been completely replaced with barium-zinc, calcium-zinc and organo-tin stabilizers. Cadmium is used in many kinds of solder and bearing alloys, because it has a low coefficient of friction and fatigue resistance. It is also found in some of the lowest-melting alloys, such as Wood's metal. === Semiconductors === Cadmium is an element in some semiconductor materials. Cadmium sulfide, cadmium selenide, and cadmium telluride are used in some photodetectors and solar cells. HgCdTe detectors are sensitive to mid-infrared light and used in some motion detectors. === Laboratory uses === Helium–cadmium lasers are a common source of blue or ultraviolet laser light. Lasers at wavelengths of 325, 354 and 442 nm are made using this gain medium; some models can switch between these wavelengths. They are notably used in fluorescence microscopy as well as various laboratory uses requiring laser light at these wavelengths. Cadmium selenide quantum dots emit bright luminescence under UV excitation (He–Cd laser, for example). The color of this luminescence can be green, yellow or red depending on the particle size. Colloidal solutions of those particles are used for imaging of biological tissues and solutions with a fluorescence microscope. In molecular biology, cadmium is used to block voltage-dependent calcium channels from fluxing calcium ions, as well as in hypoxia research to stimulate proteasome-dependent degradation of Hif-1α. Cadmium-selective sensors based on the fluorophore BODIPY have been developed for imaging and sensing of cadmium in cells. One powerful method for monitoring cadmium in aqueous environments involves electrochemistry. By employing a self-assembled monolayer one can obtain a cadmium selective electrode with a ppt-level sensitivity. == Biological role == Cadmium has no known function in higher organisms and is considered toxic. Cadmium is considered an environmental pollutant hazardous to living organisms. A cadmium-dependent carbonic anhydrase has been found in some marine diatoms, which live in environments with low zinc concentrations. Cadmium is preferentially absorbed in the kidneys of humans. Up to about 30 mg of cadmium is commonly inhaled throughout human childhood and adolescence. Cadmium is under research for its potential toxicity to increase the risk of cancer, cardiovascular disease, and osteoporosis. === Environmental impact === The biogeochemistry of cadmium and its release to the environment is under research. == Safety == Individuals and organizations have been reviewing cadmium's bioinorganic aspects for its toxicity. The most dangerous form of occupational exposure to cadmium is inhalation of fine dust and fumes, or ingestion of highly soluble cadmium compounds. Inhalation of cadmium fumes can result initially in metal fume fever, but may progress to chemical pneumonitis, pulmonary edema, and death. Cadmium is also an environmental hazard. Human exposure is primarily from fossil fuel combustion, phosphate fertilizers, natural sources, iron and steel production, cement production and related activities, nonferrous metals production, and municipal solid waste incineration. Other sources of cadmium include bread, root crops, and vegetables. There have been a few instances of general population poisoning as the result of long-term exposure to cadmium in contaminated food and water. Research into an estrogen mimicry that may induce breast cancer is ongoing, as of 2012. In the decades leading up to World War II, mining operations contaminated the Jinzū River in Japan with cadmium and traces of other toxic metals. As a consequence, cadmium accumulated in the rice crops along the riverbanks downstream of the mines. Some members of the local agricultural communities consumed the contaminated rice and developed itai-itai disease and renal abnormalities, including proteinuria and glucosuria. The victims of this poisoning were almost exclusively post-menopausal women with low iron and low body stores of other minerals. Similar general population cadmium exposures in other parts of the world have not resulted in the same health problems because the populations maintained sufficient iron and other mineral levels. Thus, although cadmium is a major factor in the itai-itai disease in Japan, most researchers have concluded that it was one of several factors. Cadmium is one of ten substances banned by the European Union's Restriction of Hazardous Substances (RoHS) directive, which regulates hazardous substances in electrical and electronic equipment, but allows for certain exemptions and exclusions from the scope of the law. The International Agency for Research on Cancer has classified cadmium and cadmium compounds as carcinogenic to humans. Although occupational exposure to cadmium is linked to lung and prostate cancer, there is still uncertainty about the carcinogenicity of cadmium in low environmental exposure. Recent data from epidemiological studies suggest that intake of cadmium through diet is associated with a higher risk of endometrial, breast, and prostate cancer as well as with osteoporosis in humans. A recent study has demonstrated that endometrial tissue is characterized by higher levels of cadmium in current and former smoking females. Cadmium exposure is associated with a large number of illnesses including kidney disease, early atherosclerosis, hypertension, and cardiovascular diseases. Although studies show a significant correlation between cadmium exposure and occurrence of disease in human populations, a molecular mechanism has not yet been identified. One hypothesis holds that cadmium is an endocrine disruptor and some experimental studies have shown that it can interact with different hormonal signaling pathways. For example, cadmium can bind to the estrogen receptor alpha, and affect signal transduction along the estrogen and MAPK signaling pathways at low doses. The tobacco plant absorbs and accumulates heavy metals such as cadmium from the surrounding soil into its leaves. Following tobacco smoke inhalation, these are readily absorbed into the body of users. Tobacco smoking is the most important single source of cadmium exposure in the general population. An estimated 10% of the cadmium content of a cigarette is inhaled through smoking. Absorption of cadmium through the lungs is more effective than through the gut. As much as 50% of the cadmium inhaled in cigarette smoke may be absorbed. On average, cadmium concentrations in the blood of smokers is 4 to 5 times greater than non-smokers and in the kidney, 2–3 times greater than in non-smokers. Despite the high cadmium content in cigarette smoke, there seems to be little exposure to cadmium from passive smoking. In a non-smoking population, food is the greatest source of exposure. High quantities of cadmium can be found in crustaceans, mollusks, offal, frog legs, cocoa solids, bitter and semi-bitter chocolate, seaweed, fungi and algae products. However, grains, vegetables, and starchy roots and tubers are consumed in much greater quantity in the U.S., and are the source of the greatest dietary exposure there. Most plants bio-accumulate metal toxins such as cadmium and when composted to form organic fertilizers, yield a product that often can contain high amounts (e.g., over 0.5 mg) of metal toxins for every kilogram of fertilizer. Fertilizers made from animal dung (e.g., cow dung) or urban waste can contain similar amounts of cadmium. The cadmium added to the soil from fertilizers (rock phosphates or organic fertilizers) become bio-available and toxic only if the soil pH is low (i.e., acidic soils). In the European Union, an analysis of almost 22,000 topsoil samples with LUCAS survey concluded that 5.5% of samples have concentrations higher than 1 mg kg-1. Zinc, copper, calcium, and iron ions, and selenium with vitamin C are used to treat cadmium intoxication, though it is not easily reversed. === Regulations === Because of the adverse effects of cadmium on the environment and human health, the supply and use of cadmium is restricted in Europe under the REACH Regulation. The EFSA Panel on Contaminants in the Food Chain specifies that 2.5 μg/kg body weight is a tolerable weekly intake for humans. The Joint FAO/WHO Expert Committee on Food Additives has declared 7 μg/kg body weight to be the provisional tolerable weekly intake level. The state of California requires a food label to carry a warning about potential exposure to cadmium on products such as cocoa powder. The European Commission has put in place the EU regulation (2019/1009) on fertilizing products (EU, 2019), adopted in June 2019 and fully applicable as of July 2022, sets a Cd limit value in phosphate fertilizers to 60 mg kg-1 of P2O5. The U.S. Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit (PEL) for cadmium at a time-weighted average (TWA) of 0.005 ppm. The National Institute for Occupational Safety and Health (NIOSH) has not set a recommended exposure limit (REL) and has designated cadmium as a known human carcinogen. The IDLH (immediately dangerous to life and health) level for cadmium is 9 mg/m3. In addition to mercury, the presence of cadmium in some batteries has led to the requirement of proper disposal (or recycling) of batteries. === Product recalls === In May 2006, a sale of the seats from Arsenal F.C.'s old stadium, Highbury in London, England was cancelled when the seats were discovered to contain trace amounts of cadmium. Reports of high levels of cadmium use in children's jewelry in 2010 led to a US Consumer Product Safety Commission investigation. The U.S. CPSC issued specific recall notices for cadmium content in jewelry sold by Claire's and Wal-Mart stores. In June 2010, McDonald's voluntarily recalled more than 12 million promotional Shrek Forever After 3D Collectible Drinking Glasses because of the cadmium levels in paint pigments on the glassware. The glasses were manufactured by Arc International, of Millville, New Jersey, USA. == See also == Red List building materials Toxic heavy metal == Notes == == References == == Further reading == Hartwig, Andrea (2013). "Cadmium and Cancer". In Astrid Sigel; Helmut Sigel; Roland K. O. Sigel (eds.). Cadmium: From Toxicity to Essentiality. Metal Ions in Life Sciences. Vol. 11. Springer. pp. 491–507. doi:10.1007/978-94-007-5179-8_15. ISBN 978-94-007-5178-1. PMID 23430782. Agency for Toxic Substances and Disease Registry (ATSDR) (2012). Toxicological Profile for Cadmium. U.S. Department of Health and Human Services, Public Health Service. https://www.atsdr.cdc.gov/toxprofiles/tp5.pdf Nordberg, Gunnar F. (2007). Handbook on the toxicology of metals (3rd ed.). Academic Press. pp. 445–486. ISBN 978-0-12-369413-3. == External links == Cadmium at The Periodic Table of Videos (University of Nottingham) ATSDR Case Studies in Environmental Medicine: Cadmium Toxicity U.S. Department of Health and Human Services National Institute for Occupational Safety and Health – Cadmium Page NLM Hazardous Substances Databank – Cadmium, Elemental

Cadmium is a chemical element; it has symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate. Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange, and yellow pigments, to color glass, and to stabilize plastic. Cadmium use is generally decreasing because it is toxic (it is specifically listed in the European Restriction of Hazardous Substances Directive) and nickel–cadmium batteries have been replaced with nickel–metal hydride and lithium-ion batteries. Due to it being a neutron poison, cadmium is also used as a component of control rods in nuclear fission reactors. One of its few new uses is in cadmium telluride solar panels. Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

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cd

Certificate of deposit (wikipedia)

A certificate of deposit (CD) is a time deposit sold by banks, thrift institutions, and credit unions in the United States. CDs typically differ from savings accounts because the CD has a specific, fixed term before money can be withdrawn without penalty and generally higher interest rates. The bank expects the CDs to be held until maturity, at which time they can be withdrawn and interest paid. In the United States, CDs are insured by the Federal Deposit Insurance Corporation (FDIC) for banks and by the National Credit Union Administration (NCUA) for credit unions. In exchange for the customer depositing the money for an agreed term, institutions usually offer higher interest rates than they do on accounts that customers can withdraw from on demand (though this may not be the case in an inverted yield curve situation). Fixed rates are the most common offering for CDs, but some institutions offer CDs with variable rates. For example, in mid-2004, interest rates were expected to rise, and many banks and credit unions began to offer CDs with a "bump-up" feature. These allow for a single readjustment of the interest rate at a time of the consumer's choosing during the term of the CD. Sometimes, financial institutions introduce CDs indexed to the stock market, bond market, or other indices. Some features of CDs are: A larger principal should or may receive a higher interest rate. A longer term usually earns a higher interest rate, except in the case of an inverted yield curve (e.g., preceding a recession). Smaller institutions tend to offer higher interest rates than larger ones. Personal CD accounts generally receive higher interest rates than business CD accounts. Banks and credit unions that lack FDIC or NCUA insurance typically provide higher interest rates. CDs typically require a minimum deposit, and may offer higher rates for larger deposits. The best rates are generally offered on "Jumbo CDs" with minimum deposits of $100,000. Jumbo CDs are commonly bought by large institutional investors, such as banks and pension funds, that are interested in low-risk and stable investment options. Jumbo CDs are also known as negotiable certificates of deposit and come in bearer form. These work like conventional certificates of deposit that lock in the principal amount for a set timeframe and are payable upon maturity. The consumer who opens a CD may receive a paper certificate, but it is now common for a CD to consist simply of a book entry and an item shown in the consumer's periodic bank statements. That is, there is often no "certificate" as such. Consumers who want a hard copy that verifies their CD purchase may request a paper statement from the bank, or print out their own from the financial institution's online banking service. == Closure == Withdrawals before maturity are usually subject to a substantial penalty. For a five-year CD, this is often the loss of up to twelve months' interest. These penalties ensure that it is generally not in a holder's best interest to withdraw the money before maturity –unless the holder has another investment with significantly higher return or has a serious need for the money. Commonly, institutions mail a notice to the CD holder shortly before the CD matures requesting directions. The notice usually offers the choice of withdrawing the principal and accumulated interest or "rolling it over", i.e. depositing it into a new CD. (Generally there is a "window" after maturity when CD can be cashed out without penalty.) In the absence of such directions, it is common for the institution to roll over the CD automatically, once again tying up the money for a period of time. Too, the CD holder may be able to specify at the time the CD is opened for it not to be rolled over. == Refinancing == The Truth in Savings Regulation DD requires that insured CDs state, at the time of account opening, the penalty for early withdrawal. It is generally accepted that these penalties cannot be revised by the depository prior to maturity. However, there have been cases in which a credit union modified its early withdrawal penalty and made it retroactive on existing accounts. The second occurrence happened when Main Street Bank of Texas closed a group of CDs early without full payment of interest. The bank claimed the disclosures allowed them to do so. The penalty for early withdrawal deters depositors from taking advantage of subsequent better investment opportunities during the term of the CD. In rising interest rate environments, the penalty may be insufficient to discourage depositors from redeeming their deposit and reinvesting the proceeds after paying the applicable early withdrawal penalty. Added interest from the new higher yielding CD may more than offset the cost of the early withdrawal penalty. == Ladders == While longer investment terms yield higher interest rates, longer-term also may result in a loss of opportunity to lock in higher interest rates in a rising-rate economy. A common mitigation strategy for this opportunity cost is the "CD ladder" strategy. In the ladder strategies, the investor distributes the deposits over a period of several years with the goal of having all one's money deposited at the longest term (and therefore the higher rate) but in a way that part of it matures annually. In this way, the depositor reaps the benefits of the longest-term rates while retaining the option to re-invest or withdraw the money in shorter-term intervals. For example, an investor beginning a three-year ladder strategy starts by depositing equal amounts of money each into a 3-year CD, 2-year CD, and 1-year CD. From that point on, a CD reaches maturity every year, at which time the investor can re-invest at a 3-year term. After two years of this cycle, the investor has all money deposited at a three-year rate, yet have one-third of the deposits mature every year (which the investor can then reinvest, augment, or withdraw). The responsibility for maintaining the ladder falls on the depositor, not the financial institution. Because the ladder does not depend on the financial institution, depositors are free to distribute a ladder strategy across more than one bank. This can be advantageous, as smaller banks may not offer the longer-term of some larger banks. Although laddering is most common with CDs, investors may use this strategy on any time deposit account with similar terms. == Step-up callable CD == Step-Up Callable CDs are a form of CD where the interest rate increases multiple times prior to maturity of the CD. These CDs are often issued with maturities up to 15 years, with a step-up in interest happening at year 5 and year 10. Typically, the beginning interest rate is higher than what is available on shorter-maturity CDs, and the rate increases with each step-up period. These CDs have a “call” feature which allows the issuer to return the deposit to the investor after a specified period of time, which is usually at least a year. When the CD is called, the investor is given back their deposit and they will no longer receive any future interest payments. Because of the call feature, interest rate risk is borne by the investor, rather than the issuer. This transfer of risk allows Step-Up Callable CDs to offer a higher interest rate than currently available from non-callable CDs. If prevailing interest rates decline, the issuer will call the CD and re-issue debt at a lower interest rate. If the CD is called before maturity, the investor is faced with reinvestment risk. If prevailing interest rates increase, the issuer will allow the CD to go to maturity. == Deposit insurance == The amount of insurance coverage varies, depending on how accounts for an individual or family are structured at the institution. The level of insurance is governed by complex FDIC and NCUA rules, available in FDIC and NCUA booklets or online. The standard insurance coverage is currently $250,000 per owner or depositor for single accounts or $250,000 per co-owner for joint accounts. Some institutions use a private insurance company instead of, or in addition to, the federally backed FDIC or NCUA deposit insurance. Institutions often stop using private supplemental insurance when they find that few customers have a high enough balance level to justify the additional cost. The Certificate of Deposit Account Registry Service program lets investors keep up to $50 million invested in CDs managed through one bank with full FDIC insurance. However rates will likely not be the highest available. == Terms and conditions == There are many variations in the terms and conditions for CDs. The federally required "Truth in Savings" booklet, or other disclosure document that gives the terms of the CD, must be made available before the purchase. Employees of the institution are generally not familiar with this information; only the written document carries legal weight. If the original issuing institution has merged with another institution, or if the CD is closed early by the purchaser, or there is some other issue, the purchaser will need to refer to the terms and conditions document to ensure that the withdrawal is processed following the original terms of the contract. The terms and conditions may be changeable. They may contain language such as "We can add to, delete or make any other changes ("Changes") we want to these Terms at any time." The CD may be callable. The terms may state that the bank or credit union can close the CD before the term ends. Payment of interest. Interest may be paid out as it is accrued or it may accumulate in the CD. Interest calculation. The CD may start earning interest from the date of deposit or from the start of the next month or quarter. Right to delay withdrawals. Institutions generally have the right to delay withdrawals for a specified period to stop a bank run. Withdrawal of principal. May be at the discretion of the financial institution. Withdrawal of principal below a certain minimum—or any withdrawal of principal at all—may require closure of the entire CD. A US Individual Retirement Account CD may allow withdrawal of IRA Required Minimum Distributions without a withdrawal penalty. Withdrawal of interest. May be limited to the most recent interest payment or allow for withdrawal of accumulated total interest since the CD was opened. Interest may be calculated to date of withdrawal or through the end of the last month or last quarter. Penalty for early withdrawal. May be measured in months of interest, may be calculated to be equal to the institution's current cost of replacing the money, or may use another formula. May or may not reduce the principal—for example, if principal is withdrawn three months after opening a CD with a six-month penalty. Fees. A fee may be specified for withdrawal or closure or for providing a certified check. Automatic renewal. The institution may or may not commit to sending a notice before automatic rollover at CD maturity. The institution may specify a grace period before automatically rolling over the CD to a new CD at maturity. Some banks have been known to renew at rates lower than that of the original CD. == Limitations == There may be some correlation between CD interest rates and inflation. For example, in one situation interest rates might be 15% and inflation 15%, and in another situation interest rates might be 2% and inflation may be 2%. Of course, these factors cancel out, so the real interest rate, which indicates the maintenance or otherwise of value, is both zero in these two examples. However the real rates of return offered by CDs, as with other fixed interest instruments, can vary significantly. For example, during a credit crunch banks are in dire need of funds, and CD interest rate increases may not track inflation. The above does not include taxes. When taxes are considered, the higher-rate situation above is worse, with a lower (more negative) real return, although the before-tax real rates of return are identical. The after-inflation, after-tax return is what is important. Author Ric Edelman writes: "You don't make any money in bank accounts (in real economic terms), simply because you're not supposed to." On the other hand, he says, bank accounts and CDs are fine for holding cash for a short amount of time. Even to the extent, that CD rates are correlated with inflation, this can only be the expected inflation at the time the CD is bought. Actual inflation may be lower or higher. Locking in the interest rate for a long term may be bad (if inflation goes up) or good (if inflation goes down). For example, in the 1970s, inflation increased higher than it had been, and this was not fully reflected in interest rates. This is particularly important, for longer-term notes, where the interest rate is locked in for some time. This gave rise to amusing nicknames for CDs. A little later, the opposite happened, and inflation declined. In general, and similar to other fixed-interest investments, the economic value of a CD rises when market interest rates fall, and vice versa. Some banks pay lower than average rates, while others pay higher rates. In the United States, depositors can take advantage of the best FDIC-insured rates without increasing their risk. As with other types of investment, investors should be suspicious of a CD offering an unusually high rate of return. Conman Allen Stanford used fraudulent CDs with high rates to lure people into his Ponzi scheme. == See also == Guaranteed investment certificate, a similar investment in Canada == References == == External links == The US SEC on buying CDs North American Securities Administrators Association on buying CDs. 2008 US SEC Litigation Release "...a scheme to defraud investors, many of them elderly, of approximately $3,661,248 by selling the investors fraudulent certificates of deposit." Liberty Bank for Savings on CD Laddering

A certificate of deposit (CD) is a time deposit sold by banks, thrift institutions, and credit unions in the United States. CDs typically differ from savings accounts because the CD has a specific, fixed term before money can be withdrawn without penalty and generally higher interest rates. The bank expects the CDs to be held until maturity, at which time they can be withdrawn and interest paid. In the United States, CDs are insured by the Federal Deposit Insurance Corporation (FDIC) for banks and by the National Credit Union Administration (NCUA) for credit unions. In exchange for the customer depositing the money for an agreed term, institutions usually offer higher interest rates than they do on accounts that customers can withdraw from on demand (though this may not be the case in an inverted yield curve situation). Fixed rates are the most common offering for CDs, but some institutions offer CDs with variable rates. For example, in mid-2004, interest rates were expected to rise, and many banks and credit unions began to offer CDs with a "bump-up" feature. These allow for a single readjustment of the interest rate at a time of the consumer's choosing during the term of the CD. Sometimes, financial institutions introduce CDs indexed to the stock market, bond market, or other indices. Some features of CDs are: A larger principal should or may receive a higher interest rate. A longer term usually earns a higher interest rate, except in the case of an inverted yield curve (e.g., preceding a recession). Smaller institutions tend to offer higher interest rates than larger ones. Personal CD accounts generally receive higher interest rates than business CD accounts. Banks and credit unions that lack FDIC or NCUA insurance typically provide higher interest rates. CDs typically require a minimum deposit, and may offer higher rates for larger deposits. The best rates are generally offered on "Jumbo CDs" with minimum deposits of $100,000. Jumbo CDs are commonly bought by large institutional investors, such as banks and pension funds, that are interested in low-risk and stable investment options. Jumbo CDs are also known as negotiable certificates of deposit and come in bearer form. These work like conventional certificates of deposit that lock in the principal amount for a set timeframe and are payable upon maturity. The consumer who opens a CD may receive a paper certificate, but it is now common for a CD to consist simply of a book entry and an item shown in the consumer's periodic bank statements. That is, there is often no "certificate" as such. Consumers who want a hard copy that verifies their CD purchase may request a paper statement from the bank, or print out their own from the financial institution's online banking service.

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cd

Compact disc (wikipedia)

The compact disc (CD) is a digital optical disc data storage format that was codeveloped by Philips and Sony to store and play digital audio recordings. It uses the Compact Disc Digital Audio format which typically provides 74 minutes of audio on a disc. In later years, the compact disc was adapted for non-audio computer data storage purposes as CD-ROM and its derivatives. First released in Japan in October 1982, the CD was the second optical disc technology to be invented, after the much larger LaserDisc (LD). By 2007, 200 billion CDs (including audio CDs, CD-ROMs and CD-Rs) had been sold worldwide. Standard CDs have a diameter of 120 mm (4.7 in), and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about 650 MiB (681,574,400 bytes) of data. Capacity is routinely extended to 80 minutes and 700 MiB (734,003,200 bytes) by arranging data more closely on the same-sized disc. The Mini CD has various diameters ranging from 60 to 80 millimetres (2.4 to 3.1 in); they have been used for CD singles or delivering device drivers. The CD gained rapid popularity in the 1990s, quickly outselling all other audio formats in the United States by 1991, ending the market dominance of the phonograph record and the cassette tape. By 2000, the CD accounted for 92.3% of the entire market share in regard to US music sales. The CD is considered the last dominant audio format of the album era, as the rise of MP3, iTunes, cellular ringtones, and other downloadable music formats in the mid-2000s ended the decade-long dominance of the CD. The Digital Audio format was later adapted (as CD-ROM) for general purpose data storage and initially could hold much more data than a personal computer hard disk drive. Several other formats were further derived, both pre-pressed and blank user writable, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video CD (VCD), Super Video CD (SVCD), Photo CD, Picture CD, Compact Disc-Interactive (CD-i), Enhanced Music CD, and Super Audio CD (SACD) which may have a CD-DA layer. == History == == Physical details == A CD is made from 1.2-millimetre (0.047 in) thick, polycarbonate plastic, and weighs 14–33 grams. From the center outward, components are: the center spindle hole (15 mm), the first-transition area (clamping ring), the clamping area (stacking ring), the second-transition area (mirror band), the program (data) area, and the rim. The inner program area occupies a radius from 25 to 58 mm. A thin layer of aluminum or, more rarely, gold is applied to the surface, making it reflective. The metal is protected by a film of lacquer normally spin coated directly on the reflective layer. The label is printed on the lacquer layer, usually by screen printing or offset printing. CD data is represented as tiny indentations known as pits, encoded in a spiral track molded into the top of the polycarbonate layer. The areas between pits are known as lands. Each pit is approximately 100 nm deep by 500 nm wide, and varies from 850 nm to 3.5 μm in length. The distance between the windings (the pitch) is 1.6 μm (measured center-to-center, not between the edges). When playing an audio CD, a motor within the CD player spins the disc to a scanning velocity of 1.2–1.4 m/s (constant linear velocity, CLV)—equivalent to approximately 500 RPM at the inside of the disc, and approximately 200 RPM at the outside edge. The track on the CD begins at the inside and spirals outward so a disc played from beginning to end slows its rotation rate during playback. The program area is 86.05 cm2 and the length of the recordable spiral is 86.05 cm2 / 1.6 μm = 5.38 km. With a scanning speed of 1.2 m/s, the playing time is 74 minutes or 650 MiB of data on a CD-ROM. A disc with data packed slightly more densely is tolerated by most players (though some old ones fail). Using a linear velocity of 1.2 m/s and a narrower track pitch of 1.5 μm increases the playing time to 80 minutes, and data capacity to 700 MiB. Even denser tracks are possible, with semi-standard 90 minute/800 MiB discs having 1.33 μm, and 99 minute/870 MiB having 1.26 μm, but compatibility suffers as density increases. A CD is read by focusing a 780 nm wavelength (near infrared) semiconductor laser through the bottom of the polycarbonate layer. The change in height between pits and lands results in a difference in the way the light is reflected. Because the pits are indented into the top layer of the disc and are read through the transparent polycarbonate base, the pits form bumps when read. The laser hits the disc, casting a circle of light wider than the modulated spiral track reflecting partially from the lands and partially from the top of any bumps where they are present. As the laser passes over a pit (bump), its height means that the round trip path of the light reflected from its peak is 1/2 wavelength out of phase with the light reflected from the land around it. This is because the height of a bump is around 1/4 of the wavelength of the light used, so the light falls 1/4 out of phase before reflection and another 1/4 wavelength out of phase after reflection. This causes partial cancellation of the laser's reflection from the surface. By measuring the reflected intensity change with a photodiode, a modulated signal is read back from the disc. To accommodate the spiral pattern of data, the laser is placed on a mobile mechanism within the disc tray of any CD player. This mechanism typically takes the form of a sled that moves along a rail. The sled can be driven by a worm gear or linear motor. Where a worm gear is used, a second shorter-throw linear motor, in the form of a coil and magnet, makes fine position adjustments to track eccentricities in the disk at high speed. Some CD drives (particularly those manufactured by Philips during the 1980s and early 1990s) use a swing arm similar to that seen on a gramophone. The pits and lands do not directly represent the 0s and 1s of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from either pit to land or land to pit indicates a 1, while no change indicates a series of 0s. There must be at least two, and no more than ten 0s between each 1, which is defined by the length of the pit. This, in turn, is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc. These encoding techniques (defined in the Red Book) were originally designed for CD Digital Audio, but they later became a standard for almost all CD formats (such as CD-ROM). === Integrity === CDs are susceptible to damage during handling and from environmental exposure. Pits are much closer to the label side of a disc, enabling defects and contaminants on the clear side to be out of focus during playback. Consequently, CDs are more likely to suffer damage on the label side of the disc. Scratches on the clear side can be repaired by refilling them with similar refractive plastic or by careful polishing. The edges of CDs are sometimes incompletely sealed, allowing gases and liquids to enter the CD and corrode the metal reflective layer and/or interfere with the focus of the laser on the pits, a condition known as disc rot. The fungus Geotrichum candidum has been found—under conditions of high heat and humidity—to consume the polycarbonate plastic and aluminium found in CDs. The data integrity of compact discs can be measured using surface error scanning, which can measure the rates of different types of data errors, known as C1, C2, CU and extended (finer-grain) error measurements known as E11, E12, E21, E22, E31 and E32, of which higher rates indicate a possibly damaged or unclean data surface, low media quality, deteriorating media and recordable media written to by a malfunctioning CD writer. Error scanning can reliably predict data losses caused by media deterioration. Support of error scanning differs between vendors and models of optical disc drives, and extended error scanning (known as "advanced error scanning" in Nero DiscSpeed) has only been available on Plextor and some BenQ optical drives so far, as of 2020. === Disc shapes and diameters === The digital data on a CD begins at the center of the disc and proceeds toward the edge, which allows adaptation to the different sizes available. Standard CDs are available in two sizes. By far, the most common is 120 millimetres (4.7 in) in diameter, with a 74-, 80, 90, or 99-minute audio capacity and a 650, 700, 800, or 870 MiB (737,280,000-byte) data capacity. Discs are 1.2 millimetres (0.047 in) thick, with a 15 millimetres (0.59 in) center hole. The size of the hole was chosen by Joop Sinjou and based on a Dutch 10-cent coin: a dubbeltje. Philips/Sony patented the physical dimensions. The official Philips history says the capacity was specified by Sony executive Norio Ohga to be able to contain the entirety of Beethoven's Ninth Symphony on one disc. This is a myth according to Kees Immink, as the EFM code format had not yet been decided in December 1979, when the 120 mm size was adopted. The adoption of EFM in June 1980 allowed 30 percent more playing time that would have resulted in 97 minutes for 120 mm diameter or 74 minutes for a disc as small as 100 millimetres (3.9 in). Instead, the information density was lowered by 30 percent to keep the playing time at 74 minutes. The 120 mm diameter has been adopted by subsequent formats, including Super Audio CD, DVD, HD DVD, and Blu-ray Disc. The 80-millimetre (3.1 in) diameter discs ("Mini CDs") can hold up to 24 minutes of music or 210 MiB. == Logical format == === Audio CD === The logical format of an audio CD (officially Compact Disc Digital Audio or CD-DA) is described in a document produced in 1980 by the format's joint creators, Sony and Philips. The document is known colloquially as the Red Book CD-DA after the color of its cover. The format is a two-channel 16-bit PCM encoding at a 44.1 kHz sampling rate per channel. Four-channel sound was to be an allowable option within the Red Book format, but has never been implemented. Monaural audio has no existing standard on a Red Book CD; thus, the mono source material is usually presented as two identical channels in a standard Red Book stereo track (i.e., mirrored mono); an MP3 CD, can have audio file formats with mono sound. CD-Text is an extension of the Red Book specification for an audio CD that allows for the storage of additional text information (e.g., album name, song name, artist) on a standards-compliant audio CD. The information is stored either in the lead-in area of the CD, where there are roughly five kilobytes of space available or in the subcode channels R to W on the disc, which can store about 31 megabytes. Compact Disc + Graphics is a special audio compact disc that contains graphics data in addition to the audio data on the disc. The disc can be played on a regular audio CD player, but when played on a special CD+G player, it can output a graphics signal (typically, the CD+G player is hooked up to a television set or a computer monitor); these graphics are almost exclusively used to display lyrics on a television set for karaoke performers to sing along with. The CD+G format takes advantage of the channels R through W. These six bits store the graphics information. CD + Extended Graphics (CD+EG, also known as CD+XG) is an improved variant of the Compact Disc + Graphics (CD+G) format. Like CD+G, CD+EG uses basic CD-ROM features to display text and video information in addition to the music being played. This extra data is stored in subcode channels R-W. Very few, if any, CD+EG discs have been published. === Super Audio CD === Super Audio CD (SACD) is a high-resolution, read-only optical audio disc format that was designed to provide higher-fidelity digital audio reproduction than the Red Book. Introduced in 1999, it was developed by Sony and Philips, the same companies that created the Red Book. SACD was in a format war with DVD-Audio, but neither has replaced audio CDs. The SACD standard is referred to as the Scarlet Book standard. Titles in the SACD format can be issued as hybrid discs; these discs contain the SACD audio stream as well as a standard audio CD layer which is playable in standard CD players, thus making them backward compatible. === CD-MIDI === CD-MIDI is a format used to store music-performance data, which upon playback is performed by electronic instruments that synthesize the audio. Hence, unlike the original Red Book CD-DA, these recordings are not digitally sampled audio recordings. The CD-MIDI format is defined as an extension of the original Red Book. === CD-ROM === For the first few years of its existence, the CD was a medium used purely for audio. In 1988, the Yellow Book CD-ROM standard was established by Sony and Philips, which defined a non-volatile optical data computer data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. === Video CD === Video CD (VCD, View CD, and Compact Disc digital video) is a standard digital format for storing video media on a CD. VCDs are playable in dedicated VCD players, most modern DVD-Video players, personal computers, and some video game consoles. The VCD standard was created in 1993 by Sony, Philips, Matsushita, and JVC and is referred to as the White Book standard. Overall picture quality is intended to be comparable to VHS video. Poorly compressed VCD video can sometimes be of lower quality than VHS video, but VCD exhibits block artifacts rather than analog noise and does not deteriorate further with each use. 352×240 (or SIF) resolution was chosen because it is half the vertical and half the horizontal resolution of the NTSC video. 352×288 is a similarly one-quarter PAL/SECAM resolution. This approximates the (overall) resolution of an analog VHS tape, which, although it has double the number of (vertical) scan lines, has a much lower horizontal resolution. === Super Video CD === Super Video CD (Super Video Compact Disc or SVCD) is a format used for storing video media on standard compact discs. SVCD was intended as a successor to VCD and an alternative to DVD-Video and falls somewhere between both in terms of technical capability and picture quality. SVCD has two-thirds the resolution of DVD, and over 2.7 times the resolution of VCD. One CD-R disc can hold up to 60 minutes of standard-quality SVCD-format video. While no specific limit on SVCD video length is mandated by the specification, one must lower the video bit rate, and therefore quality, to accommodate very long videos. It is usually difficult to fit much more than 100 minutes of video onto one SVCD without incurring a significant quality loss, and many hardware players are unable to play a video with an instantaneous bit rate lower than 300 to 600 kilobits per second. === Photo CD === Photo CD is a system designed by Kodak for digitizing and storing photos on a CD. Launched in 1992, the discs were designed to hold nearly 100 high-quality images, scanned prints, and slides using special proprietary encoding. Photo CDs are defined in the Beige Book and conform to the CD-ROM XA and CD-i Bridge specifications as well. They are intended to play on CD-i players, Photo CD players, and any computer with suitable software (irrespective of operating system). The images can also be printed out on photographic paper with a special Kodak machine. This format is not to be confused with Kodak Picture CD, which is a consumer product in CD-ROM format. === CD-i === The Philips Green Book specifies a standard for interactive multimedia compact discs designed for CD-i players (1993). CD-i discs can contain audio tracks that can be played on regular CD players, but CD-i discs are not compatible with most CD-ROM drives and software. The CD-i Ready specification was later created to improve compatibility with audio CD players, and the CD-i Bridge specification was added to create CD-i-compatible discs that can be accessed by regular CD-ROM drives. === CD-i Ready === Philips defined a format similar to CD-i called CD-i Ready, which puts CD-i software and data into the pregap of track 1. This format was supposed to be more compatible with older audio CD players. === Enhanced Music CD (CD+) === Enhanced Music CD, also known as CD Extra or CD Plus, is a format that combines audio tracks and data tracks on the same disc by putting audio tracks in a first session and data in a second session. It was developed by Philips and Sony, and it is defined in the Blue Book. === VinylDisc === VinylDisc is the hybrid of a standard audio CD and the vinyl record. The vinyl layer on the disc's label side can hold approximately three minutes of music. == Manufacture, cost, and pricing == In 1995, material costs were 30 cents for the jewel case and 10 to 15 cents for the CD. The wholesale cost of CDs was $0.75 to $1.15, while the typical retail price of a prerecorded music CD was $16.98. On average, the store received 35 percent of the retail price, the record company 27 percent, the artist 16 percent, the manufacturer 13 percent, and the distributor 9 percent. When 8-track cartridges, compact cassettes, and CDs were introduced, each was marketed at a higher price than the format they succeeded, even though the cost to produce the media was reduced. This was done because the perceived value increased. This continued from phonograph records to CDs, but was broken when Apple marketed MP3s for $0.99, and albums for $9.99. The incremental cost, though, to produce an MP3 is negligible. == Writable compact discs == === Recordable CD === Recordable Compact Discs, CD-Rs, are injection-molded with a "blank" data spiral. A photosensitive dye is then applied, after which the discs are metalized and lacquer-coated. The write laser of the CD recorder changes the color of the dye to allow the read laser of a standard CD player to see the data, just as it would with a standard stamped disc. The resulting discs can be read by most CD-ROM drives and played in most audio CD players. CD-Rs follow the Orange Book standard. CD-R recordings are designed to be permanent. Over time, the dye's physical characteristics may change causing read errors and data loss until the reading device cannot recover with error correction methods. Errors can be predicted using surface error scanning. The design life is from 20 to 100 years, depending on the quality of the discs, the quality of the writing drive, and storage conditions. Testing has demonstrated such degradation of some discs in as little as 18 months under normal storage conditions. This failure is known as disc rot, for which there are several, mostly environmental, reasons. The recordable audio CD is designed to be used in a consumer audio CD recorder. These consumer audio CD recorders use SCMS (Serial Copy Management System), an early form of digital rights management (DRM), to conform to the AHRA (Audio Home Recording Act). The Recordable Audio CD is typically somewhat more expensive than CD-R due to lower production volume and a 3 percent AHRA royalty used to compensate the music industry for the making of a copy. High-capacity recordable CD is a higher-density recording format that can hold 20% more data than conventional discs. The higher capacity is incompatible with some recorders and recording software. === ReWritable CD === CD-RW is a re-recordable medium that uses a metallic alloy instead of a dye. The write laser, in this case, is used to heat and alter the properties (amorphous vs. crystalline) of the alloy, and hence change its reflectivity. A CD-RW does not have as great a difference in reflectivity as a pressed CD or a CD-R, and so many earlier CD audio players cannot read CD-RW discs, although most later CD audio players and stand-alone DVD players can. CD-RWs follow the Orange Book standard. The ReWritable Audio CD is designed to be used in a consumer audio CD recorder, which will not (without modification) accept standard CD-RW discs. These consumer audio CD recorders use the Serial Copy Management System (SCMS), an early form of digital rights management (DRM), to conform to the United States' Audio Home Recording Act (AHRA). The ReWritable Audio CD is typically somewhat more expensive than CD-R due to (a) lower volume and (b) a 3 percent AHRA royalty used to compensate the music industry for the making of a copy. == Copy protection == The Red Book audio specification, except for a simple "anti-copy" statement in the subcode, does not include any copy protection mechanism. Known at least as early as 2001, attempts were made by record companies to market "copy-protected" non-standard compact discs, which cannot be ripped, or copied, to hard drives or easily converted to other formats (like FLAC, MP3 or Vorbis). One major drawback to these copy-protected discs is that most will not play on either computer CD-ROM drives or some standalone CD players that use CD-ROM mechanisms. Philips has stated that such discs are not permitted to bear the trademarked Compact Disc Digital Audio logo because they violate the Red Book specifications. Numerous copy-protection systems have been countered by readily available, often free, software, or even by simply turning off automatic AutoPlay to prevent the running of the DRM executable program. == See also == == References == == Further reading == Ecma International. Standard ECMA-130: Data Interchange on Read-only 120 mm Optical Data Disks (CD-ROM), 2nd edition (June 1996). Pohlmann, Kenneth C. (1992). The Compact Disc Handbook. Middleton, Wisconsin: A-R Editions. ISBN 0-89579-300-8. Peek, Hans et al. (2009) Origins and Successors of the Compact Disc. Springer Science+Business Media B.V. ISBN 978-1-4020-9552-8. Peek, Hans B., The emergence of the compact disc, IEEE Communications Magazine, Jan. 2010, pp. 10–17. Nakajima, Heitaro; Ogawa, Hiroshi (1992) Compact Disc Technology, Tokyo, Ohmsha Ltd. ISBN 4-274-03347-3. Barry, Robert (2020). Compact Disc (Object Lessons). New York: Bloomsbury. ISBN 978-1-5013-4851-8. == Notes == == External links == Video How Compact Discs are Manufactured CD-Recordable FAQ Exhaustive basics on CD-Recordable's Philips history of the CD (cache) Patent History (CD Player) – published by Philips in 2005 Patent History CD Disc – published by Philips in 2003 Sony History, Chapter 8, This is the replacement of Gramophone record ! (第8章レコードに代わるものはこれだ) – Sony website in Japanese Popularized History on Soundfountain A Media History of the Compact Disc (1-hour podcast interview)

The compact disc (CD) is a digital optical disc data storage format that was codeveloped by Philips and Sony to store and play digital audio recordings. It uses the Compact Disc Digital Audio format which typically provides 74 minutes of audio on a disc. In later years, the compact disc was adapted for non-audio computer data storage purposes as CD-ROM and its derivatives. First released in Japan in October 1982, the CD was the second optical disc technology to be invented, after the much larger LaserDisc (LD). By 2007, 200 billion CDs (including audio CDs, CD-ROMs and CD-Rs) had been sold worldwide. Standard CDs have a diameter of 120 mm (4.7 in), and are designed to hold up to 74 minutes of uncompressed stereo digital audio or about 650 MiB (681,574,400 bytes) of data. Capacity is routinely extended to 80 minutes and 700 MiB (734,003,200 bytes) by arranging data more closely on the same-sized disc. The Mini CD has various diameters ranging from 60 to 80 millimetres (2.4 to 3.1 in); they have been used for CD singles or delivering device drivers. The CD gained rapid popularity in the 1990s, quickly outselling all other audio formats in the United States by 1991, ending the market dominance of the phonograph record and the cassette tape. By 2000, the CD accounted for 92.3% of the entire market share in regard to US music sales. The CD is considered the last dominant audio format of the album era, as the rise of MP3, iTunes, cellular ringtones, and other downloadable music formats in the mid-2000s ended the decade-long dominance of the CD. The Digital Audio format was later adapted (as CD-ROM) for general purpose data storage and initially could hold much more data than a personal computer hard disk drive. Several other formats were further derived, both pre-pressed and blank user writable, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video CD (VCD), Super Video CD (SVCD), Photo CD, Picture CD, Compact Disc-Interactive (CD-i), Enhanced Music CD, and Super Audio CD (SACD) which may have a CD-DA layer.

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Environment variable (wikipedia)

An environment variable is a user-definable value that can affect the way running processes will behave on a computer. Environment variables are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store temporary files, or the HOME or USERPROFILE variable to find the directory structure owned by the user running the process. They were introduced in their modern form in 1979 with Version 7 Unix, so are included in all Unix operating system flavors and variants from that point onward including Linux and macOS. From PC DOS 2.0 in 1982, all succeeding Microsoft operating systems, including Microsoft Windows, and OS/2 also have included them as a feature, although with somewhat different syntax, usage and standard variable names. == Design == In all Unix and Unix-like systems, as well as on Windows, each process has its own separate set of environment variables. By default, when a process is created, it inherits a duplicate run-time environment of its parent process, except for explicit changes made by the parent when it creates the child. At the API level, these changes must be done between running fork and exec. Alternatively, from command shells such as bash, a user can change environment variables for a particular command invocation by indirectly invoking it via env or using the ENVIRONMENT_VARIABLE=VALUE <command> notation. A running program can access the values of environment variables for configuration purposes. Shell scripts and batch files use environment variables to communicate data and preferences to child processes. They can also be used to store temporary values for reference later in a shell script. However, in Unix, non-exported variables are preferred for this as they do not leak outside the process. In Unix, an environment variable that is changed in a script or compiled program will only affect that process and possibly child processes. The parent process and any unrelated processes will not be affected. Similarly, changing or removing a variable's value inside a DOS or Windows batch file will change the variable for the duration of COMMAND.COMor CMD.EXE's existence, respectively. In Unix, the environment variables are normally initialized during system startup by the system init startup scripts, and hence inherited by all other processes in the system. Users can, and often do, augment them in the profile script for the command shell they are using. In Microsoft Windows, each environment variable's default value is stored in the Windows Registry or set in the AUTOEXEC.BAT file. On Unix, a setuid program is given an environment chosen by its caller, but it runs with different authority from its caller. The dynamic linker will usually load code from locations specified by the environment variables $LD_LIBRARY_PATH and $LD_PRELOAD and run it with the process's authority. If a setuid program did this, it would be insecure, because its caller could get it to run arbitrary code and hence misuse its authority. For this reason, libc unsets these environment variables at startup in a setuid process. setuid programs usually unset unknown environment variables and check others or set them to reasonable values. In general, the collection of environment variables function as an associative array where both the keys and values are strings. The interpretation of characters in either string differs among systems. When data structures such as lists need to be represented, it is common to use a colon (common on Unix and Unix-like) or semicolon-delineated (common on Windows and DOS) list. == Syntax == The variables can be used both in scripts and on the command line. They are usually referenced by putting special symbols in front of or around the variable name. It is conventional for environment-variable names to be chosen to be in all upper cases. In programming code generally, this helps to distinguish environment variables from other kinds of names in the code. Environment-variable names are case sensitive on Unix-like operating systems but not on DOS, OS/2, and Windows. === Unix === In most Unix and Unix-like command-line shells, an environment variable's value is retrieved by placing a $ sign before the variable's name. If necessary, the name can also be surrounded by braces. To display the user home directory, the user may type: If xyz needed to be appended to the value of the HOME variable, one might type: In Unix and Unix-like systems, the names of environment variables are case-sensitive. The command env displays all environment variables and their values. The command printenv can also be used to print a single variable by giving that variable name as the sole argument to the command. === DOS, OS/2 and Windows === In DOS, OS/2 and Windows command-line interpreters such as COMMAND.COM and CMD.EXE, an environment variable is retrieved by placing a % sign before and after it. In DOS, OS/2 and Windows command-line interpreters as well as their API, upper or lower case is not distinguished for environment variable names. The environment variable named HOMEDRIVE contains the drive letter (plus its trailing : colon) of the user's home directory, whilst HOMEPATH contains the full path of the user's home directory within that drive. So to see the home drive and path, the user may type this: The command SET (with no arguments) displays all environment variables and their values. set can also be used to print all variables whose name begins with a given prefix by giving the prefix as the sole argument to the command. In Windows PowerShell, the user may type any of the following: In PowerShell, upper or lower case is not distinguished for environment variable names. The following command displays all environment variables and their values: === Assignment: Unix === The commands env and set can be used to set environment variables and are often incorporated directly into the shell. The following commands can also be used, but are often dependent on a certain shell. VARIABLE=value # (there must be no spaces around the equals sign) export VARIABLE # for Bourne and related shells export VARIABLE=value # for ksh, bash, and related shells setenv VARIABLE value # for csh and related shells A few simple principles govern how environment variables achieve their effect. Environment variables are local to the process in which they were set. If two shell processes are spawned and the value of an environment variable is changed in one, that change will not be seen by the other. When a child process is created, it inherits all the environment variables and their values from the parent process. Usually, when a program calls another program, it first creates a child process by forking, then the child adjusts the environment as needed and lastly the child replaces itself with the program to be called. This procedure gives the calling program control over the environment of the called program. In Unix shells, variables may be assigned without the export keyword. Variables defined in this way are displayed by the set command, but are not true environment variables, as they are stored only by the shell and are unknown to all other processes. The printenv command will not display them, and child processes do not inherit them. VARIABLE=value The prefix syntax exports a "true" environment variable to a child process without affecting the current process: VARIABLE=value program_name [arguments] The persistence of an environment variable can be session-wide or system-wide. unset is a builtin command implemented by both the Bourne shell family (sh, ksh, bash, etc.) and the C shell family (csh, tcsh, etc.) of Unix command line shells. It unsets a shell variable, removing it from memory and the shell's exported environment. It is implemented as a shell builtin, because it directly manipulates the internals of the shell. Read-only shell variables cannot be unset. If one tries to unset a read-only variable, the unset command will print an error message and return a non-zero exit code. === Assignment: DOS, OS/2 and Windows === In DOS, OS/2 and Windows command-line interpreters such as COMMAND.COM and CMD.EXE, the SET command is used to assign environment variables and values using the following arguments: An environment variable is removed via: The SET command without any arguments displays all environment variables along with their values; SET " ", zero or more spaces, will include internal variables too. In CMD.EXE, it is possible to assign local variables that will not be global using the SETLOCAL command and ENDLOCAL to restore the environment. Use the switch /? to display the internal documentation, or use the viewer help: In PowerShell, the assignment follows a syntax similar to Unix: == Examples == Examples of environment variables include: PATH: a list of directory paths. When the user types a command without providing the full path, this list is checked to see whether it contains a path that leads to the command. HOME (Unix-like) and USERPROFILE (Microsoft Windows): indicate where a user's home directory is located in the file system. HOME/{.AppName} (Unix-like) and APPDATA\{DeveloperName\AppName} (Microsoft Windows): for storing application settings. Many applications incorrectly use USERPROFILE for application settings in Windows: USERPROFILE should only be used in dialogs that allow user to choose between paths like Documents/Pictures/Downloads/Music; for programmatic purposes, APPDATA (for roaming application settings shared across multiple devices), LOCALAPPDATA (for local application settings) or PROGRAMDATA (for application settings shared between multiple OS users) should be used. TERM (Unix-like): specifies the type of computer terminal or terminal emulator being used (e.g., vt100 or dumb). PS1 (Unix-like): specifies how the prompt is displayed in the Bourne shell and variants. MAIL (Unix-like): used to indicate where a user's mail is to be found. TEMP: location where processes can store temporary files. == True environment variables == === Unix === $PATH Contains a colon-separated list of directories that the shell searches for commands that do not contain a slash in their name (commands with slashes are interpreted as file names to execute, and the shell attempts to execute the files directly). It is equivalent to the DOS, OS/2 and Windows %PATH% variable. $HOME Contains the location of the user's home directory. Although the current user's home directory can also be found out through the C-functions getpwuid and getuid, $HOME is often used for convenience in various shell scripts (and other contexts). Using the environment variable also gives the user the possibility to point to another directory. $PWD This variable points to the current directory. Equivalent to the output of the command pwd when called without arguments. $DISPLAY Contains the identifier for the display that X11 programs should use by default. $LD_LIBRARY_PATH On many Unix systems with a dynamic linker, contains a colon-separated list of directories that the dynamic linker should search for shared objects when building a process image after exec, before searching in any other directories. $LIBPATH or $SHLIB_PATH Alternatives to $LD_LIBRARY_PATH typically used on older Unix versions. $LANG, $LC_ALL, $LC_... $LANG is used to set to the default locale. For example, if the locale values are pt_BR, then the language is set to (Brazilian) Portuguese and Brazilian practice is used where relevant. Different aspects of localization are controlled by individual $LC_-variables ($LC_CTYPE, $LC_COLLATE, $LC_DATE etc.). $LC_ALL can be used to force the same locale for all aspects. $TZ Refers to time zone. It can be in several formats, either specifying the time zone itself or referencing a file (in /usr/share/zoneinfo). $BROWSER Contains a colon-separated list of a user's web browser preferences, for use by programs that need to allow the user to view content at a URL. The browsers in the list are intended to be attempted from first to last, stopping after the first one that succeeds. This arrangement allows for fallback behavior in different environments, e.g., in an X11 environment, a graphical browser (such as Firefox) can be used, but in a console environment a terminal-base browser (such a Lynx) can be used. A %s token may be present to specify where the URL should be placed; otherwise the browser should be launched with the URL as the first argument. === DOS === Under DOS, the master environment is provided by the primary command processor, which inherits the pre-environment defined in CONFIG.SYS when first loaded. Its size can be configured through the COMMAND /E:n parameter between 160 and 32767 bytes. Local environment segments inherited to child processes are typically reduced down to the size of the contents they hold. Some command-line processors (like 4DOS) allow to define a minimum amount of free environment space that will be available when launching secondary shells. While the content of environment variables remains unchanged upon storage, their names (without the "%") are always converted to uppercase, with the exception of pre-environment variables defined via the CONFIG.SYS directive SET under DR DOS 6.0 and higher (and only with SWITCHES=/L (for "allow lowercase names") under DR-DOS 7.02 and higher). In principle, MS-DOS 7.0 and higher also supports lowercase variable names (%windir%), but provides no means for the user to define them. Environment variable names containing lowercase letters are stored in the environment just like normal environment variables, but remain invisible to most DOS software, since they are written to expect uppercase variables only. Some command processors limit the maximum length of a variable name to 80 characters. While principally only limited by the size of the environment segment, some DOS and 16-bit Windows programs do not expect the contents of environment variables to exceed 128 characters. DR-DOS COMMAND.COM supports environment variables up to 255, 4DOS even up to 512 characters. Since COMMAND.COM can be configured (via /L:128..1024) to support command lines up to 1024 characters internally under MS-DOS 7.0 and higher, environment variables should be expected to contain at least 1024 characters as well. In some versions of DR-DOS, the environment passed to drivers, which often do not need their environment after installation, can be shrunken or relocated through SETENV or INSTALL[HIGH]/LOADHIGH options /Z (zero environment), /D[:loaddrive] (substitute drive, e.g. B:TSR.COM) and /E (relocate environment above program) in order to minimize the driver's effectively resulting resident memory footprint. In batch mode, non-existent environment variables are replaced by a zero-length string. Standard environment variables or reserved environment variables include: %APPEND% (supported since DOS 3.3) This variable contains a semicolon-delimited list of directories in which to search for files. It is usually changed via the APPEND /E command, which also ensures that the directory names are converted into uppercase. Some DOS software actually expects the names to be stored in uppercase and the length of the list not to exceed 121 characters, therefore the variable is best not modified via the SET command. Long filenames containing spaces or other special characters must not be quoted ("). %CONFIG% (supported since MS-DOS 6.0 and PC DOS 6.1, also supported by ROM-DOS) This variable holds the symbolic name of the currently chosen boot configuration. It is set by the DOS BIOS (IO.SYS, IBMBIO.COM, etc.) to the name defined by the corresponding CONFIG.SYS directive MENUITEM before launching the primary command processor. Its main purpose is to allow further special cases in AUTOEXEC.BAT and similar batchjobs depending on the selected option at boot time. This can be emulated under DR-DOS by utilizing the CONFIG.SYS directive SET like SET CONFIG=1. %CMDLINE% (introduced with 4DOS, also supported since MS-DOS 7.0) This variable contains the fully expanded text of the currently executing command line. It can be read by applications to detect the usage of and retrieve long command lines, since the traditional method to retrieve the command line arguments through the PSP (or related API functions) is limited to 126 characters and is no longer available when FCBs get expanded or the default DTA is used. While 4DOS supports longer command lines, COMMAND.COM still only supports a maximum of 126 characters at the prompt by default (unless overridden with /U:128..255 to specify the size of the command line buffer), but nevertheless internal command lines can become longer through f.e. variable expansion (depending on /L:128..1024 to specify the size of the internal buffer). In addition to the command-line length byte in the PSP, the PSP command line is normally limited by ASCII-13, and command lines longer than 126 characters will typically be truncated by having an ASCII-13 inserted at position 127, but this cannot be relied upon in all scenarios. The variable will be suppressed for external commands invoked with a preceding @-symbol like in @XCOPY ... for backward compatibility and in order to minimize the size of the environment when loading non-relocating terminate-and-stay-resident programs. Some beta versions of Windows Chicago used %CMDLINE% to store only the remainder of the command line excessing 126 characters instead of the complete command line. %COMSPEC% (supported since DOS 2.0) This variable contains the full 8.3 path to the command processor, typically C:\COMMAND.COM or C:\DOS\COMMAND.COM. It must not contain long filenames, but under DR-DOS it may contain file and directory passwords. It is set up by the primary command processor to point to itself (typically reflecting the settings of the CONFIG.SYS directive SHELL), so that the resident portion of the command processor can reload its transient portion from disk after the execution of larger programs. The value can be changed at runtime to reflect changes in the configuration, which would require the command processor to reload itself from other locations. The variable is also used when launching secondary shells. %COPYCMD% (supported since MS-DOS 6.2 and PC DOS 6.3, also supported by ROM-DOS) Allows a user to specify the /Y switch (to assume "Yes" on queries) as the default for the COPY, XCOPY, and MOVE commands. A default of /Y can be overridden by supplying the /-Y switch on the command line. The /Y switch instructs the command to replace existing files without prompting for confirmation. %DIRCMD% (supported since MS-DOS 5.0 and PC DOS 5.0, also supported by ROM-DOS) Allows a user to specify customized default parameters for the DIR command, including file specifications. Preset default switches can be overridden by providing the negative switch on the command line. For example, if %DIRCMD% contains the /W switch, then it can be overridden by using DIR /-W at the command line. This is similar to the environment variable %$DIR% under DOS Plus and a facility to define default switches for DIR through its /C or /R switches under DR-DOS COMMAND.COM. %DIRCMD% is also supported by the external SDIR.COM/DIR.COM Stacker commands under Novell DOS 7 and higher. %LANG% (supported since MS-DOS 7.0) This variable is supported by some tools to switch the locale for messages in multilingual issues. %LANGSPEC% (supported since MS-DOS 7.0) This variable is supported by some tools to switch the locale for messages in multilingual issues. %NO_SEP% (supported since PC DOS 6.3 and DR-DOS 7.07) This variable controls the display of thousands-separators in messages of various commands. Issued by default, they can be suppressed by specifying SET NO_SEP=ON or SET NO_SEP=1 under PC DOS. DR-DOS additionally allows to override the system's thousands-separator displayed as in f.e. SET NO_SEP=.. %PATH% (supported since DOS 2.0) This variable contains a semicolon-delimited list of directories in which the command interpreter will search for executable files. Equivalent to the Unix $PATH variable (but some DOS and Windows applications also use the list to search for data files similar to $LD_LIBRARY_PATH on Unix-like systems). It is usually changed via the PATH (or PATH /E under MS-DOS 6.0) command, which also ensures that the directory names are converted into uppercase. Some DOS software actually expects the names to be stored in uppercase and the length of the list not to exceed 123 characters, therefore the variable should better not be modified via the SET command. Long filenames containing spaces or other special characters must not be quoted ("). By default, the current directory is searched first, but some command-line processors like 4DOS allow "." (for "current directory") to be included in the list as well in order to override this search order; some DOS programs are incompatible with this extension. %PROMPT% (supported since DOS 2.0) This variable contains a $-tokenized string defining the display of the prompt. It is usually changed via the PROMPT command. %TEMP% (and %TMP%) These variables contain the path to the directory where temporary files should be stored. Operating system tools typically only use %TEMP%, whereas third-party programs also use %TMP%. Typically %TEMP% takes precedence over %TMP%. The DR-DOS family supports a number of additional standard environment variables including: %BETA% This variable contains an optional message displayed by some versions (including DR DOS 3.41) of COMMAND.COM at the startup of secondary shells. %DRDOSCFG%/%NWDOSCFG%/%OPENDOSCFG% This variable contains the directory (without trailing "\") where to search for .INI and .CFG configuration files (that is, DR-DOS application specific files like TASKMGR.INI, TASKMAX.INI, VIEWMAX.INI, FASTBACK.CFG etc., class specific files like COLORS.INI, or global files like DRDOS.INI, NWDOS.INI, OPENDOS.INI, or DOS.INI), as used by the INSTALL and SETUP commands and various DR-DOS programs like DISKOPT, DOSBOOK, EDIT, FBX, FILELINK, LOCK, SECURITY.OVL/NWLOGIN.EXE, SERNO, TASKMAX, TASKMGR, VIEWMAX, or UNDELETE. It must not contain long filenames. %DRCOMSPEC% This variable optionally holds an alternative path to the command processor taking precedence over the path defined in the %COMSPEC% variable, optionally including file and directory passwords. Alternatively, it can hold a special value of "ON" or "1" in order to enforce the usage of the %COMSPEC% variable even in scenarios where the %COMSPEC% variable may point to the wrong command-line processor, for example, when running some versions of the DR-DOS SYS command under a foreign operating system. %DRSYS% Setting this variable to "ON" or "1" will force some versions of the DR-DOS SYS command to work under foreign operating systems instead of displaying a warning. %FBP_USER% Specifies the user name used by the FastBack command FBX and {user}.FB configuration files under Novell DOS 7. %HOMEDIR% This variable may contain the home directory under DR-DOS (including DR DOS 5.0 and 6.0). %INFO% In some versions of DR-DOS COMMAND.COM this variable defines the string displayed by the $I token of the PROMPT command. It can be used, for example, to inform the user how to exit secondary shells. %LOGINNAME% In some versions of DR-DOS COMMAND.COM this variable defines the user name displayed by the $U token of the PROMPT command, as set up by f.e. login scripts for Novell NetWare. See also the similarly named pseudo-variable %LOGIN_NAME%. %MDOS_EXEC% This variable can take the values "ON" or "OFF" under Multiuser DOS. If enabled, the operating system permits applications to shell out to secondary shells with the DOS Program Area (DPA) freed in order to have maximum DOS memory available for secondary applications instead of running them in the same domain as under DOS. %NOCHAR% This variable can be used to define the character displayed by some commands in messages for "No" in [Y,N] queries, thereby overriding the current system default (typically "N" in English versions of DR-DOS). If it contains a string, only the first character, uppercased, will be taken. Some commands also support a command line parameter /Y to automatically assume "Yes" on queries, thereby suppressing such prompts. If, however, the parameter /Y:yn is used to specify the "Yes"/"No" characters (thereby overriding any %NOCHAR% setting), queries are not suppressed. See also the related CONFIG.SYS directive NOCHAR and the environment variable %YESCHAR%. %NOSOUND% Setting this variable to "ON" or "1" will disable default beeps issued by some DR-DOS commands in certain situations such as to inform the user of the completion of some operation, that user interaction is required, or when a wrong key was pressed. Command line options to specifically enable certain beeps will override this setting. %OS% This variable contains the name of the operating system in order to distinguish between different DOS-related operating systems of Digital Research-origin in batch jobs and applications. Known values include "DOSPLUS" (DOS Plus 1.2 in DOS emulation), "CPCDOS 4.1" (DOS Plus 1.2 in CP/M emulation), "DRDOS" (DR DOS 3.31-6.0, DR DOS Panther, DR DOS StarTrek, DR-DOS 7.02-7.05), "EZDOS" (EZ-DOS 3.41), "PALMDOS" and "NetWare PalmDOS" (PalmDOS 1.0), "NWDOS" (Novell DOS 7), "NWDOS7" (Novell DOS 7 Beta), "OPENDOS" (Caldera OpenDOS 7.01, Caldera DR-OpenDOS 7.02), "CDOS" (Concurrent DOS, Concurrent DOS XM), "CPCDOS" (Concurrent PC DOS), "CDOS386" (Concurrent DOS 386), "DRMDOS" (DR Multiuser DOS), "MDOS" (CCI Multiuser DOS), "IMSMDOS" (IMS Multiuser DOS), "REAL32" (REAL/32). MS-DOS INTERSVR looks for a value of "DRDOS" as well. See also the identically named environment variable %OS% later introduced in the Windows NT family. %PEXEC% In some versions of DR-DOS this variable defines the command executed by the $X token of the PROMPT command before COMMAND.COM displays the prompt after returning from external program execution. %SWITCHAR% This variable defines the SwitChar to be used for argument parsing by some DR-DOS commands. If defined, it overrides the system's current SwitChar setting. The only accepted characters are "/" (DOS style), "-" (Unix style) and "[" (CP/M style). See also the related CONFIG.SYS directive SWITCHAR (to set the system's SwitChar setting) and the %/% system information variable in some issues of DR-DOS COMMAND.COM (to retrieve the current setting for portable batchjobs). %TASKMGRWINDIR% This variable specifies the directory, where the Windows SYSTEM.INI to be used by the DR-DOS TASKMGR multitasker is located, overriding the default procedure to locate the file. %VER% This variable contains the version of the operating system in order to distinguish between different versions of DR-DOS in batch jobs and in the display of the VER command. It is also used for the $V token of the PROMPT command and affects the value returned by the system information variable %OS_VERSION%. Known values include "1.0" (PalmDOS 1.0), "1.2" (DOS Plus 1.2 in DOS emulation), "2.0" (Concurrent DOS 386 2.0), "3.0" (Concurrent DOS 386 3.0), "3.31" (DR DOS 3.31), "3.32" (DR DOS 3.32), "3.33" (DR DOS 3.33), "3.34" (DR DOS 3.34), "3.35" (DR DOS 3.35), "3.40" (DR DOS 3.40), "3.41" (DR DOS 3.41, EZ-DOS 3.41), "3.41T" (DR DOS 3.41T), "4.1" (Concurrent PC DOS 4.1), "5.0" (DR DOS 5.0, DR Multiuser DOS 5.0), "5.1" (Novell DR Multiuser DOS 5.1), "6.0" (DR Concurrent DOS XM 6.0, DR DOS 6.0), "6.2" (DR Concurrent DOS XM 6.2), "7" (Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02-7.05), "7.00" (CCI Multiuser DOS 7.00), "7.07" (DR-DOS 7.07), "7.1" (IMS Multiuser DOS 7.1), "7.21" (CCI Multiuser DOS 7.21), "7.22" (CCI Multiuser DOS 7.22) etc. %YESCHAR% This variable can be used to define the character displayed by some commands in messages for "Yes" in [Y,N] queries, thereby overriding the current system default (typically "Y" in English versions of DR-DOS). If it contains a string, only the first character, uppercased, will be taken. Some commands also support a command line parameter /Y to automatically assume "Yes" on queries, thereby suppressing such prompts. If, however, the parameter /Y:y is used to specify the "Yes" character (thereby overriding any %YESCHAR% setting), queries are not suppressed. See also the related CONFIG.SYS directive YESCHAR and the environment variable %NOCHAR%. %$CLS% This variable defines the control sequence to be sent to the console driver to clear the screen when the CLS command is issued, thereby overriding the internal default ("←[2J" under DR-DOS, "←E" under DOS Plus 1.2 on Amstrad machines as well as under Concurrent DOS, Multiuser DOS, and REAL/32 for VT52 terminals, or "←+" under Multiuser DOS for ASCII terminals). If the variable is not defined and no ANSI.SYS console driver is detected, the DR-DOS COMMAND.COM will directly clear the screen via INT 10h/AH=00h BIOS function, like MS-DOS/PC DOS COMMAND.COM does. A special \nnn-notation for octal numbers is supported to allow the definition of special characters like ESC (ASCII-27 = "←" = 1Bh = 33o), as f.e. in SET $CLS=\033[2J. To send the backslash ("\") itself, it can be doubled "\\". %$DIR% Supported by DOS Plus accepting the values "L" (long) or "W" (wide) to change the default layout of directory listings with DIR. Can be overridden using the command line options /L or /W. See also the similar environment variable %DIRCMD% and the DIR options /C and /R of the DR-DOS COMMAND.COM. %$PAGE% Supported by DOS Plus accepting the values "ON" or "OFF" for pagination control. Setting this to "ON" has the same affect as adding /P to commands supporting it (like DIR or TYPE). %$LENGTH% Used by DOS Plus to define the screen length of the console in lines. This is used to control in a portable way when the screen output should be temporarily halted until a key is pressed in conjunction with the /P option supported by various commands or with automatic pagnination. See also the related environment variables %$WIDTH% and %DIRSIZE% as well as the similar pseudo-variable %_ROWS%. %$WIDTH% Used by DOS Plus to define the screen width of the console in columns. This is used to control in a portable way the formatting of the screen output of commands like DIR /W or TYPE filename. See also the related environment variables %$LENGTH% and %DIRSIZE% as well as the similar pseudo-variable %_COLUMNS%. %$SLICE% Used by DOS Plus accepting a numerical value to control the foreground/background time slicing of multitasking programs. See also the DOS Plus command SLICE. %$ON% This variable can hold an optional control sequence to switch text highlighting, reversion or colorization on. It is used to emphasize or otherwise control the display of the file names in commands like TYPE wildcard, for example SET $ON=\033[1m with ANSI.SYS loaded or SET $ON=\016 for an IBM or ESC/P printer. For the special \nnn octal notation supported, see %$CLS%. While the variable is undefined by default under DOS Plus and DR-DOS, the Multiuser DOS default for an ASCII terminal equals SET $ON=\033p. See also the related environment variable %$OFF%. %$OFF% This variable can hold an optional control sequence to switch text highlighting, reversion or colorization off. It is used to return to the normal output after the display of file names in commands like TYPE wildcard, for example SET $OFF=\033[0m with ANSI.SYS loaded or SET $OFF=\024 for an IBM or ESC/P printer. For the special \nnn octal notation supported, see %$CLS%. While the variable is undefined by default under DOS Plus and DR-DOS, the Multiuser DOS default for an ASCII terminal equals SET $OFF=\033q. See also the related environment variable %$ON%. %$HEADER% This variable can hold an optional control sequence issued before the output of the file contents in commands like TYPE under DR-DOS 7.02 and higher. It can be used for highlighting, pagination or formatting, f.e. when sending the output to a printer, i.e. SET $HEADER=\017 for an IBM or ESC/P printer. For the special \nnn octal notation supported, see %$CLS%. See also the related environment variable %$FOOTER%. %$FOOTER% This variable can hold an optional control sequence issued after the output of the file contents in commands like TYPE under DR-DOS 7.02 and higher. It is used to return to the normal output format, i.e. SET $FOOTER=\022\014 in the printer example above. For the special \nnn octal notation supported, see %$CLS%. See also the related environment variable %$HEADER%. Datalight ROM-DOS supports a number of additional standard environment variables as well including: %DIRSIZE% This variable is used to define non-standard screen sizes rows[,cols] for DIR options /P and /W (similar to %$LENGTH% and %$WIDTH% under DOS Plus). %NEWFILE% This variable is automatically set to the first parameter given to the CONFIG.SYS directive NEWFILE. %TZ%, %COMM%, %SOCKETS%, %HTTP_DIR%, %HOSTNAME% and %FTPDIR% are also used by ROM-DOS. === OS/2 === %BEGINLIBPATH% Contains a semicolon-separated list of directories which are searched for DLLs before the directories given by the %LIBPATH% variable (which is set during system startup with the special CONFIG.SYS directive LIBPATH). It is possible to specify relative directories here, including "." for the current working directory. See also the related environment variable %ENDLIBPATH%. %ENDLIBPATH% a list of directories to be searched for DLLs like %BEGINLIBPATH%, but searched after the list of directories in %LIBPATH%. === Windows === These environment variables refer to locations of critical operating system resources, and as such generally are not user-dependent. %APPDATA% Contains the full path to the Application Data directory of the logged-in user. Does not work on Windows NT 4.0 SP6 UK. %LOCALAPPDATA% This variable is the temporary files of Applications. Its uses include storing of desktop themes, Windows error reporting, caching and profiles of web browsers. %ComSpec%/%COMSPEC% The %ComSpec% variable contains the full path to the command processor; on the Windows NT family of operating systems, this is cmd.exe, while on Windows 9x, %COMSPEC% is COMMAND.COM. %OS% The %OS% variable contains a symbolic name of the operating system family to distinguish between differing feature sets in batchjobs. It resembles an identically named environment variable %OS% found in all DOS-related operating systems of Digital Research-origin like Concurrent DOS, Multiuser DOS, REAL/32, DOS Plus, DR DOS, Novell DOS and OpenDOS. %OS% always holds the string "Windows_NT" on the Windows NT family. %PATH% This variable contains a semicolon-delimited (do not put spaces in between) list of directories in which the command interpreter will search for an executable file that matches the given command. Environment variables that represent paths may be nested within the %PATH% variable, but only at one level of indirection. If this sub-path environment variable itself contains an environment variable representing a path, %PATH% will not expand properly in the variable substitution. Equivalent to the Unix $PATH variable. %ProgramFiles%, %ProgramFiles(x86)%, %ProgramW6432% The %ProgramFiles% variable points to the Program Files directory, which stores all the installed programs of Windows and others. The default on English-language systems is "C:\Program Files". In 64-bit editions of Windows (XP, 2003, Vista), there are also %ProgramFiles(x86)%, which defaults to "C:\Program Files (x86)", and %ProgramW6432%, which defaults to "C:\Program Files". The %ProgramFiles% itself depends on whether the process requesting the environment variable is itself 32-bit or 64-bit (this is caused by Windows-on-Windows 64-bit redirection). %CommonProgramFiles% This variable points to the Common Files directory. The default is "C:\Program Files\Common Files" in the English version of Windows. %OneDrive% The %OneDrive% variable is a special system-wide environment variable found on Windows NT and its derivatives. Its value is the path of where (if installed and setup) the Onedrive directory is located. The value of %OneDrive% is in most cases "C:\Users\{Username}\OneDrive\". %SystemDrive% The %SystemDrive% variable is a special system-wide environment variable found on Windows NT and its derivatives. Its value is the drive upon which the system directory was placed. The value of %SystemDrive% is in most cases "C:". %SystemRoot% The %SystemRoot% variable is a special system-wide environment variable found on the Windows NT family of operating systems. Its value is the location of the system directory, including the drive and path. The drive is the same as %SystemDrive% and the default path on a clean installation depends upon the version of the operating system. By default: Windows XP and newer versions use "\WINDOWS". Windows 2000, NT 4.0 and NT 3.1 use "\WINNT". Windows NT 3.5 and NT 3.51 uses "\WINNT35". Windows NT 4.0 Terminal Server uses "\WTSRV". %windir% This variable points to the Windows directory. (On the Windows NT family of operating systems, it is identical to the %SystemRoot% variable). Windows 95–98 and Windows ME are, by default, installed in "C:\Windows". For other versions of Windows, see the %SystemRoot% entry above. User management variables store information related to resources and settings owned by various user profiles within the system. As a general rule, these variables do not refer to critical system resources or locations that are necessary for the OS to run. %ALLUSERSPROFILE% (%PROGRAMDATA% since Windows Vista) This variable expands to the full path to the All Users profile directory. This profile contains resources and settings that are used by all system accounts. Shortcut links copied to the All Users\' Start menu or Desktop directories will appear in every user's Start menu or Desktop, respectively. %USERDOMAIN% The name of the Workgroup or Windows Domain to which the current user belongs. The related variable, %LOGONSERVER%, holds the hostname of the server that authenticated the current user's login credentials (name and password). For home PCs and PCs in a workgroup, the authenticating server is usually the PC itself. For PCs in a Windows domain, the authenticating server is a domain controller (a primary domain controller, or PDC, in Windows NT 4-based domains). %USERPROFILE% A special system-wide environment variable found on Windows NT and its derivatives. Its value is the location of the current user's profile directory, in which is found that user's HKCU registry hive (NTUSER). Users can also use the %USERNAME% variable to determine the active users login identification. Optional System variables are not explicitly specified by default but can be used to modify the default behavior of certain built-in console commands. These variables also do not need to be explicitly specified as command line arguments. ==== Default values ==== The following tables shows typical default values of certain environment variables under English versions of Windows as they can be retrieved under CMD. (Some of these variables are also defined when running COMMAND.COM under Windows, but differ in certain important details: Under COMMAND.COM, the names of environment variable are always uppercased. Some, but not all variables contain short 8.3 rather than long file names. While some variables present in the CMD environment are missing, there are also some variables specific to the COMMAND environment.) In this list, there is no environment variable that refers to the location of the user's My Documents directory, so there is no standard method for setting a program's home directory to be the My Documents directory. == Pseudo-environment variables == The command processors in DOS and Windows also support pseudo-environment variables. These are values that are fetched like environment variables, but are not truly stored in the environment but computed when requested. === DOS === Besides true environment variables, which are statically stored in the environment until changed or deleted, a number of pseudo-environment variables exist for batch processing. The so-called replacement parameters or replaceable parameters (Microsoft / IBM terminology) aka replacement variables (Digital Research / Novell / Caldera terminology) or batch file parameters (JP Software terminology) %1..%9 and %0 can be used to retrieve the calling parameters of a batchjob, see SHIFT. In batchjobs, they can be retrieved just like environment variables, but are not actually stored in the environment. Some command-line processors (like DR-DOS COMMAND.COM, Multiuser DOS MDOS.COM/TMP.EXE (Terminal Message Process), JP Software 4DOS, 4OS2, 4NT, Take Command and Windows cmd.exe) support a type of pseudo-environment variables named system information variables (Novell / Caldera terminology) or internal variables (JP Software terminology), which can be used to retrieve various possibly dynamic, but read-only information about the running system in batch jobs. The returned values represent the status of the system in the moment these variables are queried; that is, reading them multiple times in a row may return different values even within the same command; querying them has no direct effect on the system. Since they are not stored in the environment, they are not listed by SET and do not exist for external programs to retrieve. If a true environment variable of the same name is defined, it takes precedence over the corresponding variable until the environment variable is deleted again. They are not case-sensitive. While almost all such variables are prefixed with an underscore ("_") by 4DOS etc. by convention (f.e. %_SECOND%), they are not under DR-DOS COMMAND.COM (f.e. %OS_VERSION%). In addition, 4DOS, 4OS2, 4NT, and Take Command also support so called variable functions, including user-definable ones. They work just like internal variables, but can take optional parameters (f.e. %@EVAL[]%) and may even change the system status depending on their function. System information variables supported by DR-DOS COMMAND.COM: %AM_PM% This pseudo-variable returns the ante- or post-midday status of the current time. The returned string depends on the locale-specific version of DR-DOS, f.e. "am" or "pm" in the English version. It resembles an identically named identifier variable in Novell NetWare login scripts. %DAY% This pseudo-variable returns the days of the current date in a 2-digit format with leading zeros, f.e. "01".."31". See also the similar pseudo-variable %_DAY%. It resembles an identically named identifier variable in Novell NetWare login scripts. %DAY_OF_WEEK% This pseudo-variable returns the day name of the week in a 3-character format. The returned string depends on the locale-specific version of DR-DOS, f.e. "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", or "Sat" in the English version. It resembles an identically named identifier variable in Novell NetWare login scripts. %ERRORLEVEL% In COMMAND.COM of DR-DOS 7.02 and higher, this pseudo-variable returns the last error level returned by an external program or the RETURN command, f.e. "0".."255". See also the identically named pseudo-variable %ERRORLEVEL% under Windows and the IF ERRORLEVEL conditional command. %ERRORLVL% In DR-DOS 7.02 and higher, this pseudo-variable returns the last error level in a 3-digit format with leading zeros, f.e. "000".."255". Under Multiuser DOS, this is a true environment variable automatically updated by the shell to the return code of exiting programs. See also the related pseudo-variable %ERRORLEVEL% under DR-DOS and the IF ERRORLEVEL command. %GREETING_TIME% This pseudo-variable returns the 3-level day greeting time. The returned string depends on the locale-specific version of DR-DOS, f.e. "morning", "afternoon", or "evening" in the English version. It resembles an identically named identifier variable in Novell NetWare login scripts. %HOUR% This pseudo-variable returns the hours of the current time in 12-hour format without leading zeros, f.e. "1".."12". It resembles an identically named identifier variable in Novell NetWare login scripts. %HOUR24% This pseudo-variable returns the hours of the current time in 24-hour format in a 2-digit format with leading zeros, f.e. "00".."23". It resembles an identically named identifier variable in Novell NetWare login scripts. See also the similar pseudo-variable %_HOUR%. %MINUTE% This pseudo-variable returns the minutes of the current time in a 2-digit format with leading zeros, f.e "00".."59". It resembles an identically named identifier variable in Novell NetWare login scripts. See also the similar pseudo-variable %_MINUTE%. %MONTH% This pseudo-variable returns the months of the current date in a 2-digit format with leading zeros, f.e. "01".."12". It resembles an identically named identifier variable in Novell NetWare login scripts. See also the similar pseudo-variable %_MONTH%. %MONTH_NAME% This pseudo-variable returns the month name of the current date. The returned string depends on the locale-specific version of DR-DOS, f.e. "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", or "December" in the English version. It resembles an identically named identifier variable in Novell NetWare login scripts. %NDAY_OF_WEEK% This pseudo-variable returns the number of day of the current week, f.e. "1".."7" (with "1" for Sunday). It resembles an identically named identifier variable in Novell NetWare login scripts. %OS_VERSION% This pseudo-variable returns the version of the operating system depending on the current setting of the environment variable %VER%. If %VER% is not defined, %OS_VERSION% returns "off". It resembles an identically named identifier variable in Novell NetWare login scripts, which may return versions also for non-DR-DOS versions of DOS. %SECOND% This pseudo-variable returns the seconds of the current time in a 2-digit format with leading zeros, f.e. "00".."59". It resembles an identically named identifier variable in Novell NetWare login scripts. See also the similar pseudo-variable %_SECOND%. %SHORT_YEAR% This pseudo-variable returns the year of the current date in a 2-digit format with leading zeros, f.e. "93".."99", "00".."92". It resembles an identically named identifier variable in Novell NetWare login scripts. %YEAR% and %_YEAR% Supported since Novell DOS 7, the %YEAR% pseudo-variable returns the year of the current date in a 4-digit format, f.e. "1980".."2099". It resembles an identically named identifier variable in Novell NetWare login scripts. DR-DOS 7.02 and higher added %_YEAR% for compatibility with 4DOS, returning the same value. %/% In COMMAND.COM of DR-DOS 7.02 and higher, this pseudo-variable returns the current SwitChar setting of the system, either "/" (DOS style) or "-" (Unix style). See also the related CONFIG.SYS directive SWITCHAR and the environment variable %SWITCHAR%. %_CODEPAGE% This pseudo-variable returns the systems' current code page ("1".."65533"), f.e. "437", "850", "858". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the CHCP command. %_COLUMNS% This pseudo-variable returns the current number of screen columns depending on the display mode, f.e. "40", "80", "132", etc. This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also a similar environment variable %$WIDTH% under DOS Plus. %_COUNTRY% This pseudo-variable returns the systems' current country code ("1".."65534"), f.e. "1" for USA, "44" for UK, "49" for Germany, "20049" with ISO 8601, "21049" with ISO 8601 and Euro support. This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the CONFIG.SYS directive COUNTRY. %_DAY% This pseudo-variable returns the days of the current date without leading zeros, f.e. "1".."31". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the similar pseudo-variable %DAY%. %_HOUR% This pseudo-variable returns the hours of the current time in 24-hour format without leading zeros, f.e. "0".."23". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the similar pseudo-variable %HOUR24%. %_MINUTE% This pseudo-variable returns the minutes of the current time without leading zeros, f.e "0".."59". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the similar pseudo-variable %MINUTE%. %_MONTH% This pseudo-variable returns the months of the current date without leading zeros, f.e. "1".."12". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the similar pseudo-variable %MONTH%. %_ROWS% This pseudo-variable returns the current number of screen rows depending on the display mode, f.e. "25", "43", "50", etc. This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See a similar environment variable %$LENGTH% under DOS Plus. %_SECOND% This pseudo-variable returns the seconds of the current time without leading zeros, f.e. "0".."59". This variable was originally introduced by 4DOS, but also became available with COMMAND.COM since DR-DOS 7.02. See also the similar pseudo-variable %SECOND%. System information variables supported by DR-DOS COMMAND.COM with networking loaded: %LOGIN_NAME% This pseudo-variable returns the user name. This always worked with NETX, but it will also work with Personal NetWare's ODI/VLM if the current drive is a PNW-mapped drive (otherwise an empty string is returned). See also the similarly named environment variable %LOGINNAME%. %P_STATION% This pseudo-variable returns the physical station number in a format "????????????". The value depends on the MAC address of the network adapter, but can be overridden. It resembles an identically named identifier variable in Novell NetWare login scripts. %STATION% This pseudo-variable returns the logical station number starting with "1" for the first client. The numbers are assigned by the file server and remain static for as long as the IPX connection remains established. It resembles an identically named identifier variable in Novell NetWare login scripts. %FULL_NAME% This pseudo-variable returns the full name of the logged in user, if available. It resembles an identically named identifier variable in Novell NetWare login scripts. See also the related pseudo-variable %LOGIN_NAME%. === Windows === Dynamic environment variables (also named internal variables or system information variables under DOS) are pseudo-environment variables supported by CMD.EXE when command-line extensions are enabled, and they expand to various discrete values whenever queried, that is, their values can change when queried multiple times even within the same command. While they can be used in batch jobs and at the prompt, they are not stored in the environment. Consequently, they are neither listed by SET nor do they exist for external programs to read. They are not case-sensitive. Indirectly, they are also supported under Windows' COMMAND.COM, which has been modified to internally call CMD.EXE to execute the commands. %CD% This pseudo-variable expands to the current directory equivalent to the output of the command CD when called without arguments. While a long filename can be returned under CMD.EXE depending on the current directory, the fact that the current directory will always be in 8.3 format under COMMAND.COM will cause it to return a short filename under COMMAND.COM, even when COMMAND internally calls CMD. %CMDCMDLINE% This pseudo-variable expands to the original startup parameters of CMD.EXE, f.e. "C:\Windows\system32\cmd.exe". Under Windows' COMMAND.COM, this may return something like "C:\Windows\system32\cmd.exe /c ..." due to the fact that COMMAND.COM calls CMD.EXE internally. %CMDEXTVERSION% This pseudo-variable expands to the version of the command-line extensions of CMD.EXE, if enabled (e.g. "1" under Windows NT, "2" under Windows 2000 and Windows XP). %DATE% This pseudo-variable expands to the current date. The date is displayed according to the current user's date format preferences. %ERRORLEVEL% This pseudo-variable expands to the last set error level, a value between "0" and "255" (without leading zeros). External commands and some internal commands set error levels upon execution. See also the identically named pseudo-variable %ERRORLEVEL% under DR-DOS and the IF ERRORLEVEL command. %HIGHESTNUMANODENUMBER% This pseudo-variable returns the number of the highest NUMA node. %RANDOM% This pseudo-variable returns a random number between "0" and "32767". %TIME% This pseudo-variable returns the current time. The time is displayed according to the current user's time format preferences. If the %TIME% and %DATE% variables are both used, it is important to read them both in this particular order in rapid succession in order to avoid midnight-rollover problems. === Other shells === Unix-like shells have similar dynamically generated variables, bash's $RANDOM being a well-known example. However, since these shells have a concept of local variables, they are described as special local variables instead. == See also == Variable (computer science) List of Unix commands List of DOS commands Special folder Modules Environment PWB shell Windows Registry == Notes == == References == == Further reading == Chen, Raymond (2010-05-06). "What are these strange =C: environment variables?". The New Old Thing. Microsoft. Archived from the original on 2018-05-27. Retrieved 2017-05-27. == External links == environ(7): user environment – Linux Programmer's Manual – Overview, Conventions and Miscellanea environ(7) – FreeBSD Miscellaneous Information Manual environ(7) – Darwin and macOS Miscellaneous Information Manual environ(7) – Solaris 11.4 Standards, Environments, Macros, Character Sets, and Miscellany Reference Manual "Environment Variables Wiki". Archived from the original on 2019-04-27. User Environment Variables fix setx.exe not found bug

An environment variable is a user-definable value that can affect the way running processes will behave on a computer. Environment variables are part of the environment in which a process runs. For example, a running process can query the value of the TEMP environment variable to discover a suitable location to store temporary files, or the HOME or USERPROFILE variable to find the directory structure owned by the user running the process. They were introduced in their modern form in 1979 with Version 7 Unix, so are included in all Unix operating system flavors and variants from that point onward including Linux and macOS. From PC DOS 2.0 in 1982, all succeeding Microsoft operating systems, including Microsoft Windows, and OS/2 also have included them as a feature, although with somewhat different syntax, usage and standard variable names.

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Jacobi elliptic functions (wikipedia)

In mathematics, the Jacobi elliptic functions are a set of basic elliptic functions. They are found in the description of the motion of a pendulum (see also pendulum (mathematics)), as well as in the design of electronic elliptic filters. While trigonometric functions are defined with reference to a circle, the Jacobi elliptic functions are a generalization which refer to other conic sections, the ellipse in particular. The relation to trigonometric functions is contained in the notation, for example, by the matching notation sn {\displaystyle \operatorname {sn} } for sin {\displaystyle \sin } . The Jacobi elliptic functions are used more often in practical problems than the Weierstrass elliptic functions as they do not require notions of complex analysis to be defined and/or understood. They were introduced by Carl Gustav Jakob Jacobi (1829). Carl Friedrich Gauss had already studied special Jacobi elliptic functions in 1797, the lemniscate elliptic functions in particular, but his work was published much later. == Overview == There are twelve Jacobi elliptic functions denoted by pq ⁡ ( u , m ) {\displaystyle \operatorname {pq} (u,m)} , where p {\displaystyle \mathrm {p} } and q {\displaystyle \mathrm {q} } are any of the letters c {\displaystyle \mathrm {c} } , s {\displaystyle \mathrm {s} } , n {\displaystyle \mathrm {n} } , and d {\displaystyle \mathrm {d} } . (Functions of the form pp ⁡ ( u , m ) {\displaystyle \operatorname {pp} (u,m)} are trivially set to unity for notational completeness.) u {\displaystyle u} is the argument, and m {\displaystyle m} is the parameter, both of which may be complex. In fact, the Jacobi elliptic functions are meromorphic in both u {\displaystyle u} and m {\displaystyle m} . The distribution of the zeros and poles in the u {\displaystyle u} -plane is well-known. However, questions of the distribution of the zeros and poles in the m {\displaystyle m} -plane remain to be investigated. In the complex plane of the argument u {\displaystyle u} , the twelve functions form a repeating lattice of simple poles and zeroes. Depending on the function, one repeating parallelogram, or unit cell, will have sides of length 2 K {\displaystyle 2K} or 4 K {\displaystyle 4K} on the real axis, and 2 K ′ {\displaystyle 2K'} or 4 K ′ {\displaystyle 4K'} on the imaginary axis, where K = K ( m ) {\displaystyle K=K(m)} and K ′ = K ( 1 − m ) {\displaystyle K'=K(1-m)} are known as the quarter periods with K ( ⋅ ) {\displaystyle K(\cdot )} being the elliptic integral of the first kind. The nature of the unit cell can be determined by inspecting the "auxiliary rectangle" (generally a parallelogram), which is a rectangle formed by the origin ( 0 , 0 ) {\displaystyle (0,0)} at one corner, and ( K , K ′ ) {\displaystyle (K,K')} as the diagonally opposite corner. As in the diagram, the four corners of the auxiliary rectangle are named s {\displaystyle \mathrm {s} } , c {\displaystyle \mathrm {c} } , d {\displaystyle \mathrm {d} } , and n {\displaystyle \mathrm {n} } , going counter-clockwise from the origin. The function pq ⁡ ( u , m ) {\displaystyle \operatorname {pq} (u,m)} will have a zero at the p {\displaystyle \mathrm {p} } corner and a pole at the q {\displaystyle \mathrm {q} } corner. The twelve functions correspond to the twelve ways of arranging these poles and zeroes in the corners of the rectangle. When the argument u {\displaystyle u} and parameter m {\displaystyle m} are real, with 0 < m < 1 {\displaystyle 0<m<1} , K {\displaystyle K} and K ′ {\displaystyle K'} will be real and the auxiliary parallelogram will in fact be a rectangle, and the Jacobi elliptic functions will all be real valued on the real line. Since the Jacobian elliptic functions are doubly periodic in u {\displaystyle u} , they factor through a torus – in effect, their domain can be taken to be a torus, just as cosine and sine are in effect defined on a circle. Instead of having only one circle, we now have the product of two circles, one real and the other imaginary. The complex plane can be replaced by a complex torus. The circumference of the first circle is 4 K {\displaystyle 4K} and the second 4 K ′ {\displaystyle 4K'} , where K {\displaystyle K} and K ′ {\displaystyle K'} are the quarter periods. Each function has two zeroes and two poles at opposite positions on the torus. Among the points 0 {\displaystyle 0} , K {\displaystyle K} , K + i K ′ {\displaystyle K+iK'} , i K ′ {\displaystyle iK'} there is one zero and one pole. The Jacobian elliptic functions are then doubly periodic, meromorphic functions satisfying the following properties: There is a simple zero at the corner p {\displaystyle \mathrm {p} } , and a simple pole at the corner q {\displaystyle \mathrm {q} } . The complex number p − q {\displaystyle \mathrm {p} -\mathrm {q} } is equal to half the period of the function pq ⁡ u {\displaystyle \operatorname {pq} u} ; that is, the function pq ⁡ u {\displaystyle \operatorname {pq} u} is periodic in the direction pq {\displaystyle \operatorname {pq} } , with the period being 2 ( p − q ) {\displaystyle 2(\mathrm {p} -\mathrm {q} )} . The function pq ⁡ u {\displaystyle \operatorname {pq} u} is also periodic in the other two directions p p ′ {\displaystyle \mathrm {pp} '} and p q ′ {\displaystyle \mathrm {pq} '} , with periods such that p − p ′ {\displaystyle \mathrm {p} -\mathrm {p} '} and p − q ′ {\displaystyle \mathrm {p} -\mathrm {q} '} are quarter periods. == Notation == The elliptic functions can be given in a variety of notations, which can make the subject unnecessarily confusing. Elliptic functions are functions of two variables. The first variable might be given in terms of the amplitude φ {\displaystyle \varphi } , or more commonly, in terms of u {\displaystyle u} given below. The second variable might be given in terms of the parameter m {\displaystyle m} , or as the elliptic modulus k {\displaystyle k} , where k 2 = m {\displaystyle k^{2}=m} , or in terms of the modular angle α {\displaystyle \alpha } , where m = sin 2 ⁡ α {\displaystyle m=\sin ^{2}\alpha } . The complements of k {\displaystyle k} and m {\displaystyle m} are defined as m ′ = 1 − m {\displaystyle m'=1-m} and k ′ = m ′ {\textstyle k'={\sqrt {m'}}} . These four terms are used below without comment to simplify various expressions. The twelve Jacobi elliptic functions are generally written as pq ⁡ ( u , m ) {\displaystyle \operatorname {pq} (u,m)} where p {\displaystyle \mathrm {p} } and q {\displaystyle \mathrm {q} } are any of the letters c {\displaystyle \mathrm {c} } , s {\displaystyle \mathrm {s} } , n {\displaystyle \mathrm {n} } , and d {\displaystyle \mathrm {d} } . Functions of the form pp ⁡ ( u , m ) {\displaystyle \operatorname {pp} (u,m)} are trivially set to unity for notational completeness. The “major” functions are generally taken to be cn ⁡ ( u , m ) {\displaystyle \operatorname {cn} (u,m)} , sn ⁡ ( u , m ) {\displaystyle \operatorname {sn} (u,m)} and dn ⁡ ( u , m ) {\displaystyle \operatorname {dn} (u,m)} from which all other functions can be derived and expressions are often written solely in terms of these three functions, however, various symmetries and generalizations are often most conveniently expressed using the full set. (This notation is due to Gudermann and Glaisher and is not Jacobi's original notation.) Throughout this article, pq ⁡ ( u , t 2 ) = pq ⁡ ( u ; t ) {\displaystyle \operatorname {pq} (u,t^{2})=\operatorname {pq} (u;t)} . The functions are notationally related to each other by the multiplication rule: (arguments suppressed) pq ⋅ p ′ q ′ = p q ′ ⋅ p ′ q {\displaystyle \operatorname {pq} \cdot \operatorname {p'q'} =\operatorname {pq'} \cdot \operatorname {p'q} } from which other commonly used relationships can be derived: pr qr = pq {\displaystyle {\frac {\operatorname {pr} }{\operatorname {qr} }}=\operatorname {pq} } pr ⋅ rq = pq {\displaystyle \operatorname {pr} \cdot \operatorname {rq} =\operatorname {pq} } 1 qp = pq {\displaystyle {\frac {1}{\operatorname {qp} }}=\operatorname {pq} } The multiplication rule follows immediately from the identification of the elliptic functions with the Neville theta functions pq ⁡ ( u , m ) = θ p ( u , m ) θ q ( u , m ) {\displaystyle \operatorname {pq} (u,m)={\frac {\theta _{\operatorname {p} }(u,m)}{\theta _{\operatorname {q} }(u,m)}}} Also note that: K ( m ) = K ( k 2 ) = ∫ 0 1 d t ( 1 − t 2 ) ( 1 − m t 2 ) = ∫ 0 1 d t ( 1 − t 2 ) ( 1 − k 2 t 2 ) . {\displaystyle K(m)=K(k^{2})=\int _{0}^{1}{\frac {dt}{\sqrt {(1-t^{2})(1-mt^{2})}}}=\int _{0}^{1}{\frac {dt}{\sqrt {(1-t^{2})(1-k^{2}t^{2})}}}.} == Definition in terms of inverses of elliptic integrals == There is a definition, relating the elliptic functions to the inverse of the incomplete elliptic integral of the first kind F {\displaystyle F} . These functions take the parameters u {\displaystyle u} and m {\displaystyle m} as inputs. The φ {\displaystyle \varphi } that satisfies u = F ( φ , m ) = ∫ 0 φ d θ 1 − m sin 2 ⁡ θ {\displaystyle u=F(\varphi ,m)=\int _{0}^{\varphi }{\frac {\mathrm {d} \theta }{\sqrt {1-m\sin ^{2}\theta }}}} is called the Jacobi amplitude: am ⁡ ( u , m ) = φ . {\displaystyle \operatorname {am} (u,m)=\varphi .} In this framework, the elliptic sine sn u (Latin: sinus amplitudinis) is given by sn ⁡ ( u , m ) = sin ⁡ am ⁡ ( u , m ) {\displaystyle \operatorname {sn} (u,m)=\sin \operatorname {am} (u,m)} and the elliptic cosine cn u (Latin: cosinus amplitudinis) is given by cn ⁡ ( u , m ) = cos ⁡ am ⁡ ( u , m ) {\displaystyle \operatorname {cn} (u,m)=\cos \operatorname {am} (u,m)} and the delta amplitude dn u (Latin: delta amplitudinis) dn ⁡ ( u , m ) = d d u am ⁡ ( u , m ) . {\displaystyle \operatorname {dn} (u,m)={\frac {\mathrm {d} }{\mathrm {d} u}}\operatorname {am} (u,m).} In the above, the value m {\displaystyle m} is a free parameter, usually taken to be real such that 0 ≤ m ≤ 1 {\displaystyle 0\leq m\leq 1} (but can be complex in general), and so the elliptic functions can be thought of as being given by two variables, u {\displaystyle u} and the parameter m {\displaystyle m} . The remaining nine elliptic functions are easily built from the above three ( sn {\displaystyle \operatorname {sn} } , cn {\displaystyle \operatorname {cn} } , dn {\displaystyle \operatorname {dn} } ), and are given in a section below. In the most general setting, am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} is a multivalued function (in u {\displaystyle u} ) with infinitely many logarithmic branch points (the branches differ by integer multiples of 2 π {\displaystyle 2\pi } ), namely the points 2 s K ( m ) + ( 4 t + 1 ) K ( 1 − m ) i {\displaystyle 2sK(m)+(4t+1)K(1-m)i} and 2 s K ( m ) + ( 4 t + 3 ) K ( 1 − m ) i {\displaystyle 2sK(m)+(4t+3)K(1-m)i} where s , t ∈ Z {\displaystyle s,t\in \mathbb {Z} } . This multivalued function can be made single-valued by cutting the complex plane along the line segments joining these branch points (the cutting can be done in non-equivalent ways, giving non-equivalent single-valued functions), thus making am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} analytic everywhere except on the branch cuts. In contrast, sin ⁡ am ⁡ ( u , m ) {\displaystyle \sin \operatorname {am} (u,m)} and other elliptic functions have no branch points, give consistent values for every branch of am {\displaystyle \operatorname {am} } , and are meromorphic in the whole complex plane. Since every elliptic function is meromorphic in the whole complex plane (by definition), am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} (when considered as a single-valued function) is not an elliptic function. However, a particular cutting for am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} can be made in the u {\displaystyle u} -plane by line segments from 2 s K ( m ) + ( 4 t + 1 ) K ( 1 − m ) i {\displaystyle 2sK(m)+(4t+1)K(1-m)i} to 2 s K ( m ) + ( 4 t + 3 ) K ( 1 − m ) i {\displaystyle 2sK(m)+(4t+3)K(1-m)i} with s , t ∈ Z {\displaystyle s,t\in \mathbb {Z} } ; then it only remains to define am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} at the branch cuts by continuity from some direction. Then am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} becomes single-valued and singly-periodic in u {\displaystyle u} with the minimal period 4 i K ( 1 − m ) {\displaystyle 4iK(1-m)} and it has singularities at the logarithmic branch points mentioned above. If m ∈ R {\displaystyle m\in \mathbb {R} } and m ≤ 1 {\displaystyle m\leq 1} , am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} is continuous in u {\displaystyle u} on the real line. When m > 1 {\displaystyle m>1} , the branch cuts of am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} in the u {\displaystyle u} -plane cross the real line at 2 ( 2 s + 1 ) K ( 1 / m ) / m {\displaystyle 2(2s+1)K(1/m)/{\sqrt {m}}} for s ∈ Z {\displaystyle s\in \mathbb {Z} } ; therefore for m > 1 {\displaystyle m>1} , am ⁡ ( u , m ) {\displaystyle \operatorname {am} (u,m)} is not continuous in u {\displaystyle u} on the real line and jumps by 2 π {\displaystyle 2\pi } on the discontinuities. Let E ( φ , m ) = ∫ 0 φ 1 − m sin 2 ⁡ θ d θ {\displaystyle E(\varphi ,m)=\int _{0}^{\varphi }{\sqrt {1-m\sin ^{2}\theta }}\,\mathrm {d} \theta } be the incomplete elliptic integral of the second kind with parameter m {\displaystyle m} . Then the Jacobi epsilon function can be defined as E ( u , m ) = E ( am ⁡ ( u , m ) , m ) {\displaystyle {\mathcal {E}}(u,m)=E(\operatorname {am} (u,m),m)} for u ∈ R {\displaystyle u\in \mathbb {R} } and 0 < m < 1 {\displaystyle 0<m<1} and by analytic continuation in each of the variables otherwise: the Jacobi epsilon function is meromorphic in the whole complex plane (in both u {\displaystyle u} and m {\displaystyle m} ). Alternatively, throughout both the u {\displaystyle u} -plane and m {\displaystyle m} -plane, E ( u , m ) = ∫ 0 u dn 2 ⁡ ( t , m ) d t . {\displaystyle {\mathcal {E}}(u,m)=\int _{0}^{u}\operatorname {dn} ^{2}(t,m)\,\mathrm {d} t.} So the Jacobi epsilon relates the incomplete elliptic integral of the first kind to the incomplete elliptic integral of the second kind: E ( φ , m ) = E ( F ( φ , m ) , m ) . {\displaystyle E(\varphi ,m)={\mathcal {E}}(F(\varphi ,m),m).} The Jacobi epsilon function is not an elliptic function, but it appears when differentiating the Jacobi elliptic functions with respect to the parameter. The Jacobi zn function is defined by zn ⁡ ( u , m ) = E ( u , m ) − E ( m ) K ( m ) u . {\displaystyle \operatorname {zn} (u,m)={\mathcal {E}}(u,m)-{\frac {E(m)}{K(m)}}u.} It is a singly periodic function which is meromorphic in u {\displaystyle u} , but not in m {\displaystyle m} (due to the branch cuts of E {\displaystyle E} and K {\displaystyle K} ). Its minimal period in u {\displaystyle u} is 2 K ( m ) {\displaystyle 2K(m)} . It is related to the Jacobi zeta function by Z ( φ , m ) = zn ⁡ ( F ( φ , m ) , m ) . {\displaystyle Z(\varphi ,m)=\operatorname {zn} (F(\varphi ,m),m).} Note that when φ = π / 2 {\displaystyle \varphi =\pi /2} , that u {\displaystyle u} then equals the quarter period K {\displaystyle K} . == Definition as trigonometry: the Jacobi ellipse == cos ⁡ φ , sin ⁡ φ {\displaystyle \cos \varphi ,\sin \varphi } are defined on the unit circle, with radius r = 1 and angle φ = {\displaystyle \varphi =} arc length of the unit circle measured from the positive x-axis. Similarly, Jacobi elliptic functions are defined on the unit ellipse, with a = 1. Let x 2 + y 2 b 2 = 1 , b > 1 , m = 1 − 1 b 2 , 0 < m < 1 , x = r cos ⁡ φ , y = r sin ⁡ φ {\displaystyle {\begin{aligned}&x^{2}+{\frac {y^{2}}{b^{2}}}=1,\quad b>1,\\&m=1-{\frac {1}{b^{2}}},\quad 0<m<1,\\&x=r\cos \varphi ,\quad y=r\sin \varphi \end{aligned}}} then: r ( φ , m ) = 1 1 − m sin 2 ⁡ φ . {\displaystyle r(\varphi ,m)={\frac {1}{\sqrt {1-m\sin ^{2}\varphi }}}\,.} For each angle φ {\displaystyle \varphi } the parameter u = u ( φ , m ) = ∫ 0 φ r ( θ , m ) d θ {\displaystyle u=u(\varphi ,m)=\int _{0}^{\varphi }r(\theta ,m)\,d\theta } (the incomplete elliptic integral of the first kind) is computed. On the unit circle ( a = b = 1 {\displaystyle a=b=1} ), u {\displaystyle u} would be an arc length. The quantity u [ φ , k ] = u ( φ , k 2 ) {\displaystyle u[\varphi ,k]=u(\varphi ,k^{2})} is related to the incomplete elliptic integral of the second kind (with modulus k {\displaystyle k} ) by u [ φ , k ] = 1 1 − k 2 ( 1 + 1 − k 2 2 E ⁡ ( φ + arctan ⁡ ( 1 − k 2 tan ⁡ φ ) , 1 − 1 − k 2 1 + 1 − k 2 ) − E ⁡ ( φ , k ) + k 2 sin ⁡ φ cos ⁡ φ 2 1 − k 2 sin 2 ⁡ φ ) , {\displaystyle u[\varphi ,k]={\frac {1}{\sqrt {1-k^{2}}}}\left({\frac {1+{\sqrt {1-k^{2}}}}{2}}\operatorname {E} \left(\varphi +\arctan \left({\sqrt {1-k^{2}}}\tan \varphi \right),{\frac {1-{\sqrt {1-k^{2}}}}{1+{\sqrt {1-k^{2}}}}}\right)-\operatorname {E} (\varphi ,k)+{\frac {k^{2}\sin \varphi \cos \varphi }{2{\sqrt {1-k^{2}\sin ^{2}\varphi }}}}\right),} and therefore is related to the arc length of an ellipse. Let P = ( x , y ) = ( r cos ⁡ φ , r sin ⁡ φ ) {\displaystyle P=(x,y)=(r\cos \varphi ,r\sin \varphi )} be a point on the ellipse, and let P ′ = ( x ′ , y ′ ) = ( cos ⁡ φ , sin ⁡ φ ) {\displaystyle P'=(x',y')=(\cos \varphi ,\sin \varphi )} be the point where the unit circle intersects the line between P {\displaystyle P} and the origin O {\displaystyle O} . Then the familiar relations from the unit circle: x ′ = cos ⁡ φ , y ′ = sin ⁡ φ {\displaystyle x'=\cos \varphi ,\quad y'=\sin \varphi } read for the ellipse: x ′ = cn ⁡ ( u , m ) , y ′ = sn ⁡ ( u , m ) . {\displaystyle x'=\operatorname {cn} (u,m),\quad y'=\operatorname {sn} (u,m).} So the projections of the intersection point P ′ {\displaystyle P'} of the line O P {\displaystyle OP} with the unit circle on the x- and y-axes are simply cn ⁡ ( u , m ) {\displaystyle \operatorname {cn} (u,m)} and sn ⁡ ( u , m ) {\displaystyle \operatorname {sn} (u,m)} . These projections may be interpreted as 'definition as trigonometry'. In short: cn ⁡ ( u , m ) = x r ( φ , m ) , sn ⁡ ( u , m ) = y r ( φ , m ) , dn ⁡ ( u , m ) = 1 r ( φ , m ) . {\displaystyle \operatorname {cn} (u,m)={\frac {x}{r(\varphi ,m)}},\quad \operatorname {sn} (u,m)={\frac {y}{r(\varphi ,m)}},\quad \operatorname {dn} (u,m)={\frac {1}{r(\varphi ,m)}}.} For the x {\displaystyle x} and y {\displaystyle y} value of the point P {\displaystyle P} with u {\displaystyle u} and parameter m {\displaystyle m} we get, after inserting the relation: r ( φ , m ) = 1 dn ⁡ ( u , m ) {\displaystyle r(\varphi ,m)={\frac {1}{\operatorname {dn} (u,m)}}} into: x = r ( φ , m ) cos ⁡ ( φ ) , y = r ( φ , m ) sin ⁡ ( φ ) {\displaystyle x=r(\varphi ,m)\cos(\varphi ),y=r(\varphi ,m)\sin(\varphi )} that: x = cn ⁡ ( u , m ) dn ⁡ ( u , m ) , y = sn ⁡ ( u , m ) dn ⁡ ( u , m ) . {\displaystyle x={\frac {\operatorname {cn} (u,m)}{\operatorname {dn} (u,m)}},\quad y={\frac {\operatorname {sn} (u,m)}{\operatorname {dn} (u,m)}}.} The latter relations for the x- and y-coordinates of points on the unit ellipse may be considered as generalization of the relations x = cos ⁡ φ , y = sin ⁡ φ {\displaystyle x=\cos \varphi ,y=\sin \varphi } for the coordinates of points on the unit circle. The following table summarizes the expressions for all Jacobi elliptic functions pq(u,m) in the variables (x,y,r) and (φ,dn) with r = x 2 + y 2 {\textstyle r={\sqrt {x^{2}+y^{2}}}} == Definition in terms of Jacobi theta functions == === Jacobi theta function description === Equivalently, Jacobi's elliptic functions can be defined in terms of his theta functions. If we abbreviate ϑ 00 ( 0 ; q ) {\displaystyle \vartheta _{00}(0;q)} as ϑ 00 ( q ) {\displaystyle \vartheta _{00}(q)} , and ϑ 01 ( 0 ; q ) , ϑ 10 ( 0 ; q ) , ϑ 11 ( 0 ; q ) {\displaystyle \vartheta _{01}(0;q),\vartheta _{10}(0;q),\vartheta _{11}(0;q)} respectively as ϑ 01 ( q ) , ϑ 10 ( q ) , ϑ 11 ( q ) {\displaystyle \vartheta _{01}(q),\vartheta _{10}(q),\vartheta _{11}(q)} (the theta constants) then the theta function elliptic modulus k is k = { ϑ 10 [ q ( k ) ] ϑ 00 [ q ( k ) ] } 2 {\displaystyle k={\biggl \{}{\vartheta _{10}[q(k)] \over \vartheta _{00}[q(k)]}{\biggr \}}^{2}} . We define the nome as q = exp ⁡ ( π i τ ) {\displaystyle q=\exp(\pi i\tau )} in relation to the period ratio. We have sn ⁡ ( u ; k ) = − ϑ 00 ( q ) ϑ 11 ( ζ ; q ) ϑ 10 ( q ) ϑ 01 ( ζ ; q ) cn ⁡ ( u ; k ) = ϑ 01 ( q ) ϑ 10 ( ζ ; q ) ϑ 10 ( q ) ϑ 01 ( ζ ; q ) dn ⁡ ( u ; k ) = ϑ 01 ( q ) ϑ 00 ( ζ ; q ) ϑ 00 ( q ) ϑ 01 ( ζ ; q ) {\displaystyle {\begin{aligned}\operatorname {sn} (u;k)&=-{\frac {\vartheta _{00}(q)\,\vartheta _{11}(\zeta ;q)}{\vartheta _{10}(q)\,\vartheta _{01}(\zeta ;q)}}\\[7pt]\operatorname {cn} (u;k)&={\frac {\vartheta _{01}(q)\,\vartheta _{10}(\zeta ;q)}{\vartheta _{10}(q)\,\vartheta _{01}(\zeta ;q)}}\\[7pt]\operatorname {dn} (u;k)&={\frac {\vartheta _{01}(q)\,\vartheta _{00}(\zeta ;q)}{\vartheta _{00}(q)\,\vartheta _{01}(\zeta ;q)}}\end{aligned}}} where ζ = π u / ( 2 K ) {\displaystyle \zeta =\pi u/(2K)} . Edmund Whittaker and George Watson defined the Jacobi theta functions this way in their textbook A Course of Modern Analysis: ϑ 00 ( v ; w ) = ∏ n = 1 ∞ ( 1 − w 2 n ) [ 1 + 2 cos ⁡ ( 2 v ) w 2 n − 1 + w 4 n − 2 ] {\displaystyle \vartheta _{00}(v;w)=\prod _{n=1}^{\infty }(1-w^{2n})[1+2\cos(2v)w^{2n-1}+w^{4n-2}]} ϑ 01 ( v ; w ) = ∏ n = 1 ∞ ( 1 − w 2 n ) [ 1 − 2 cos ⁡ ( 2 v ) w 2 n − 1 + w 4 n − 2 ] {\displaystyle \vartheta _{01}(v;w)=\prod _{n=1}^{\infty }(1-w^{2n})[1-2\cos(2v)w^{2n-1}+w^{4n-2}]} ϑ 10 ( v ; w ) = 2 w 1 / 4 cos ⁡ ( v ) ∏ n = 1 ∞ ( 1 − w 2 n ) [ 1 + 2 cos ⁡ ( 2 v ) w 2 n + w 4 n ] {\displaystyle \vartheta _{10}(v;w)=2w^{1/4}\cos(v)\prod _{n=1}^{\infty }(1-w^{2n})[1+2\cos(2v)w^{2n}+w^{4n}]} ϑ 11 ( v ; w ) = − 2 w 1 / 4 sin ⁡ ( v ) ∏ n = 1 ∞ ( 1 − w 2 n ) [ 1 − 2 cos ⁡ ( 2 v ) w 2 n + w 4 n ] {\displaystyle \vartheta _{11}(v;w)=-2w^{1/4}\sin(v)\prod _{n=1}^{\infty }(1-w^{2n})[1-2\cos(2v)w^{2n}+w^{4n}]} The Jacobi zn function can be expressed by theta functions as well: zn ⁡ ( u ; k ) = π 2 K ϑ 01 ′ ( ζ ; q ) ϑ 01 ( ζ ; q ) = π 2 K ϑ 00 ′ ( ζ ; q ) ϑ 00 ( ζ ; q ) + k 2 sn ⁡ ( u ; k ) cn ⁡ ( u ; k ) dn ⁡ ( u ; k ) = π 2 K ϑ 10 ′ ( ζ ; q ) ϑ 10 ( ζ ; q ) + dn ⁡ ( u ; k ) sn ⁡ ( u ; k ) cn ⁡ ( u ; k ) = π 2 K ϑ 11 ′ ( ζ ; q ) ϑ 11 ( ζ ; q ) − cn ⁡ ( u ; k ) dn ⁡ ( u ; k ) sn ⁡ ( u ; k ) {\displaystyle {\begin{aligned}\operatorname {zn} (u;k)&={\frac {\pi }{2K}}{\frac {\vartheta _{01}'(\zeta ;q)}{\vartheta _{01}(\zeta ;q)}}\\&={\frac {\pi }{2K}}{\frac {\vartheta _{00}'(\zeta ;q)}{\vartheta _{00}(\zeta ;q)}}+k^{2}{\frac {\operatorname {sn} (u;k)\operatorname {cn} (u;k)}{\operatorname {dn} (u;k)}}\\&={\frac {\pi }{2K}}{\frac {\vartheta _{10}'(\zeta ;q)}{\vartheta _{10}(\zeta ;q)}}+{\frac {\operatorname {dn} (u;k)\operatorname {sn} (u;k)}{\operatorname {cn} (u;k)}}\\&={\frac {\pi }{2K}}{\frac {\vartheta _{11}'(\zeta ;q)}{\vartheta _{11}(\zeta ;q)}}-{\frac {\operatorname {cn} (u;k)\operatorname {dn} (u;k)}{\operatorname {sn} (u;k)}}\end{aligned}}} where ′ {\displaystyle '} denotes the derivative with respect to the first variable. === Elliptic integral and elliptic nome === Since the Jacobi functions are defined in terms of the elliptic modulus k ( τ ) {\displaystyle k(\tau )} , we need to invert this and find τ {\displaystyle \tau } in terms of k {\displaystyle k} . We start from k ′ = 1 − k 2 {\displaystyle k'={\sqrt {1-k^{2}}}} , the complementary modulus. As a function of τ {\displaystyle \tau } it is k ′ ( τ ) = 1 − k 2 = { ϑ 01 [ q ( k ) ] ϑ 00 [ q ( k ) ] } 2 {\displaystyle k'(\tau )={\sqrt {1-k^{2}}}={\biggl \{}{\vartheta _{01}[q(k)] \over \vartheta _{00}[q(k)]}{\biggr \}}^{2}} Let us define the elliptic nome and the complete elliptic integral of the first kind: q ( k ) = exp ⁡ [ − π K ( 1 − k 2 ) K ( k ) ] {\displaystyle q(k)=\exp {\biggl [}-\pi {\frac {K({\sqrt {1-k^{2}}})}{K(k)}}{\biggr ]}} These are two identical definitions of the complete elliptic integral of the first kind: K ( k ) = ∫ 0 π / 2 1 1 − k 2 sin ⁡ ( φ ) 2 ∂ φ {\displaystyle K(k)=\int _{0}^{\pi /2}{\frac {1}{\sqrt {1-k^{2}\sin(\varphi )^{2}}}}\partial \varphi } K ( k ) = π 2 ∑ a = 0 ∞ [ ( 2 a ) ! ] 2 16 a ( a ! ) 4 k 2 a {\displaystyle K(k)={\frac {\pi }{2}}\sum _{a=0}^{\infty }{\frac {[(2a)!]^{2}}{16^{a}(a!)^{4}}}k^{2a}} An identical definition of the nome function can be produced by using a series. Following function has this identity: 1 − 1 − k 2 4 1 + 1 − k 2 4 = ϑ 00 [ q ( k ) ] − ϑ 01 [ q ( k ) ] ϑ 00 [ q ( k ) ] + ϑ 01 [ q ( k ) ] = [ ∑ n = 1 ∞ 2 q ( k ) ( 2 n − 1 ) 2 ] [ 1 + ∑ n = 1 ∞ 2 q ( k ) 4 n 2 ] − 1 {\displaystyle {\frac {1-{\sqrt[{4}]{1-k^{2}}}}{1+{\sqrt[{4}]{1-k^{2}}}}}={\frac {\vartheta _{00}[q(k)]-\vartheta _{01}[q(k)]}{\vartheta _{00}[q(k)]+\vartheta _{01}[q(k)]}}={\biggl [}\sum _{n=1}^{\infty }2\,q(k)^{(2n-1)^{2}}{\biggr ]}{\biggl [}1+\sum _{n=1}^{\infty }2\,q(k)^{4n^{2}}{\biggr ]}^{-1}} Since we may reduce to the case where the imaginary part of τ {\displaystyle \tau } is greater than or equal to 3 / 2 {\displaystyle {\sqrt {3}}/2} (see Modular group), we can assume the absolute value of q {\displaystyle q} is less than or equal to exp ⁡ ( − π 3 / 2 ) ≈ 0.0658 {\displaystyle \exp(-\pi {\sqrt {3}}/2)\approx 0.0658} ; for values this small the above series converges very rapidly and easily allows us to find the appropriate value for q {\displaystyle q} . By solving this function after q we get: q ( k ) = ∑ n = 1 ∞ Sw ( n ) 2 4 n − 3 ( 1 − 1 − k 2 4 1 + 1 − k 2 4 ) 4 n − 3 = k 2 { 1 2 + [ ∑ n = 1 ∞ Sw ( n + 1 ) 2 4 n + 1 k 2 n ] } 4 {\displaystyle q(k)=\sum _{n=1}^{\infty }{\frac {{\text{Sw}}(n)}{2^{4n-3}}}{\biggl (}{\frac {1-{\sqrt[{4}]{1-k^{2}}}}{1+{\sqrt[{4}]{1-k^{2}}}}}{\biggr )}^{4n-3}=k^{2}{\biggl \{}{\frac {1}{2}}+{\biggl [}\sum _{n=1}^{\infty }{\frac {{\text{Sw}}(n+1)}{2^{4n+1}}}k^{2n}{\biggr ]}{\biggr \}}^{4}} Where SW(n) is sequence A002103 in the OEIS. == Definition in terms of Neville theta functions == The Jacobi elliptic functions can be defined very simply using the Neville theta functions: pq ⁡ ( u , m ) = θ p ( u , m ) θ q ( u , m ) {\displaystyle \operatorname {pq} (u,m)={\frac {\theta _{\operatorname {p} }(u,m)}{\theta _{\operatorname {q} }(u,m)}}} Simplifications of complicated products of the Jacobi elliptic functions are often made easier using these identities. == Jacobi transformations == === The Jacobi imaginary transformations === The Jacobi imaginary transformations relate various functions of the imaginary variable i u or, equivalently, relations between various values of the m parameter. In terms of the major functions:: 506 cn ⁡ ( u , m ) = nc ⁡ ( i u , 1 − m ) {\displaystyle \operatorname {cn} (u,m)=\operatorname {nc} (i\,u,1\!-\!m)} sn ⁡ ( u , m ) = − i sc ⁡ ( i u , 1 − m ) {\displaystyle \operatorname {sn} (u,m)=-i\operatorname {sc} (i\,u,1\!-\!m)} dn ⁡ ( u , m ) = dc ⁡ ( i u , 1 − m ) {\displaystyle \operatorname {dn} (u,m)=\operatorname {dc} (i\,u,1\!-\!m)} Using the multiplication rule, all other functions may be expressed in terms of the above three. The transformations may be generally written as pq ⁡ ( u , m ) = γ pq pq ′ ⁡ ( i u , 1 − m ) {\displaystyle \operatorname {pq} (u,m)=\gamma _{\operatorname {pq} }\operatorname {pq} '(i\,u,1\!-\!m)} . The following table gives the γ pq pq ′ ⁡ ( i u , 1 − m ) {\displaystyle \gamma _{\operatorname {pq} }\operatorname {pq} '(i\,u,1\!-\!m)} for the specified pq(u,m). (The arguments ( i u , 1 − m ) {\displaystyle (i\,u,1\!-\!m)} are suppressed) Since the hyperbolic trigonometric functions are proportional to the circular trigonometric functions with imaginary arguments, it follows that the Jacobi functions will yield the hyperbolic functions for m=1.: 249 In the figure, the Jacobi curve has degenerated to two vertical lines at x = 1 and x = −1. === The Jacobi real transformations === The Jacobi real transformations: 308 yield expressions for the elliptic functions in terms with alternate values of m. The transformations may be generally written as pq ⁡ ( u , m ) = γ pq pq ′ ⁡ ( k u , 1 / m ) {\displaystyle \operatorname {pq} (u,m)=\gamma _{\operatorname {pq} }\operatorname {pq} '(k\,u,1/m)} . The following table gives the γ pq pq ′ ⁡ ( k u , 1 / m ) {\displaystyle \gamma _{\operatorname {pq} }\operatorname {pq} '(k\,u,1/m)} for the specified pq(u,m). (The arguments ( k u , 1 / m ) {\displaystyle (k\,u,1/m)} are suppressed) === Other Jacobi transformations === Jacobi's real and imaginary transformations can be combined in various ways to yield three more simple transformations .: 214 The real and imaginary transformations are two transformations in a group (D3 or anharmonic group) of six transformations. If μ R ( m ) = 1 / m {\displaystyle \mu _{R}(m)=1/m} is the transformation for the m parameter in the real transformation, and μ I ( m ) = 1 − m = m ′ {\displaystyle \mu _{I}(m)=1-m=m'} is the transformation of m in the imaginary transformation, then the other transformations can be built up by successive application of these two basic transformations, yielding only three more possibilities: μ I R ( m ) = μ I ( μ R ( m ) ) = − m ′ / m μ R I ( m ) = μ R ( μ I ( m ) ) = 1 / m ′ μ R I R ( m ) = μ R ( μ I ( μ R ( m ) ) ) = − m / m ′ {\displaystyle {\begin{aligned}\mu _{IR}(m)&=&\mu _{I}(\mu _{R}(m))&=&-m'/m\\\mu _{RI}(m)&=&\mu _{R}(\mu _{I}(m))&=&1/m'\\\mu _{RIR}(m)&=&\mu _{R}(\mu _{I}(\mu _{R}(m)))&=&-m/m'\end{aligned}}} These five transformations, along with the identity transformation (μU(m) = m) yield the six-element group. With regard to the Jacobi elliptic functions, the general transformation can be expressed using just three functions: cs ⁡ ( u , m ) = γ i c s ′ ⁡ ( γ i u , μ i ( m ) ) {\displaystyle \operatorname {cs} (u,m)=\gamma _{i}\operatorname {cs'} (\gamma _{i}u,\mu _{i}(m))} ns ⁡ ( u , m ) = γ i n s ′ ⁡ ( γ i u , μ i ( m ) ) {\displaystyle \operatorname {ns} (u,m)=\gamma _{i}\operatorname {ns'} (\gamma _{i}u,\mu _{i}(m))} ds ⁡ ( u , m ) = γ i d s ′ ⁡ ( γ i u , μ i ( m ) ) {\displaystyle \operatorname {ds} (u,m)=\gamma _{i}\operatorname {ds'} (\gamma _{i}u,\mu _{i}(m))} where i = U, I, IR, R, RI, or RIR, identifying the transformation, γi is a multiplication factor common to these three functions, and the prime indicates the transformed function. The other nine transformed functions can be built up from the above three. The reason the cs, ns, ds functions were chosen to represent the transformation is that the other functions will be ratios of these three (except for their inverses) and the multiplication factors will cancel. The following table lists the multiplication factors for the three ps functions, the transformed m's, and the transformed function names for each of the six transformations.: 214 (As usual, k2 = m, 1 − k2 = k12 = m′ and the arguments ( γ i u , μ i ( m ) {\displaystyle \gamma _{i}u,\mu _{i}(m)} ) are suppressed) Thus, for example, we may build the following table for the RIR transformation. The transformation is generally written pq ⁡ ( u , m ) = γ pq p q ′ ⁡ ( k ′ u , − m / m ′ ) {\displaystyle \operatorname {pq} (u,m)=\gamma _{\operatorname {pq} }\,\operatorname {pq'} (k'\,u,-m/m')} (The arguments ( k ′ u , − m / m ′ ) {\displaystyle (k'\,u,-m/m')} are suppressed) The value of the Jacobi transformations is that any set of Jacobi elliptic functions with any real-valued parameter m can be converted into another set for which 0 < m ≤ 1 / 2 {\displaystyle 0<m\leq 1/2} and, for real values of u, the function values will be real.: p. 215 === Amplitude transformations === am ⁡ ( m ′ u , − m m ′ ) = π 2 − am ⁡ ( K − u , m ) , u ∈ R , 0 < m < 1 , {\displaystyle \operatorname {am} \left({\sqrt {m'}}u,-{\frac {m}{m'}}\right)={\frac {\pi }{2}}-\operatorname {am} (K-u,m),\quad u\in \mathbb {R} ,\,0<m<1,} am ⁡ ( u , m ′ ) = − 2 arctan ⁡ ( i tan ⁡ am ⁡ ( i u , m ) 2 ) , | Re ⁡ u | < K ′ , | Im ⁡ u | < K , 0 < m < 1 , {\displaystyle \operatorname {am} (u,m')=-2\arctan \left(i\tan {\frac {\operatorname {am} (iu,m)}{2}}\right),\quad \left|\operatorname {Re} u\right|<K',\,\left|\operatorname {Im} u\right|<K,\,0<m<1,} am ⁡ ( m u , 1 m ) = arcsin ⁡ ( m sn ⁡ ( u , m ) ) , − 2 K < u < 2 K , 0 < m < 1 {\displaystyle \operatorname {am} \left({\sqrt {m}}u,{\frac {1}{m}}\right)=\arcsin({\sqrt {m}}\operatorname {sn} (u,m)),\quad -2K<u<2K,\,0<m<1} == The Jacobi hyperbola == Introducing complex numbers, our ellipse has an associated hyperbola: x 2 − y 2 b 2 = 1 {\displaystyle x^{2}-{\frac {y^{2}}{b^{2}}}=1} from applying Jacobi's imaginary transformation to the elliptic functions in the above equation for x and y. x = 1 dn ⁡ ( u , 1 − m ) , y = sn ⁡ ( u , 1 − m ) dn ⁡ ( u , 1 − m ) {\displaystyle x={\frac {1}{\operatorname {dn} (u,1-m)}},\quad y={\frac {\operatorname {sn} (u,1-m)}{\operatorname {dn} (u,1-m)}}} It follows that we can put x = dn ⁡ ( u , 1 − m ) , y = sn ⁡ ( u , 1 − m ) {\displaystyle x=\operatorname {dn} (u,1-m),y=\operatorname {sn} (u,1-m)} . So our ellipse has a dual ellipse with m replaced by 1-m. This leads to the complex torus mentioned in the Introduction. Generally, m may be a complex number, but when m is real and m<0, the curve is an ellipse with major axis in the x direction. At m=0 the curve is a circle, and for 0<m<1, the curve is an ellipse with major axis in the y direction. At m = 1, the curve degenerates into two vertical lines at x = ±1. For m > 1, the curve is a hyperbola. When m is complex but not real, x or y or both are complex and the curve cannot be described on a real x-y diagram. == Minor functions == Reversing the order of the two letters of the function name results in the reciprocals of the three functions above: ns ⁡ ( u ) = 1 sn ⁡ ( u ) , nc ⁡ ( u ) = 1 cn ⁡ ( u ) , nd ⁡ ( u ) = 1 dn ⁡ ( u ) . {\displaystyle \operatorname {ns} (u)={\frac {1}{\operatorname {sn} (u)}},\qquad \operatorname {nc} (u)={\frac {1}{\operatorname {cn} (u)}},\qquad \operatorname {nd} (u)={\frac {1}{\operatorname {dn} (u)}}.} Similarly, the ratios of the three primary functions correspond to the first letter of the numerator followed by the first letter of the denominator: sc ⁡ ( u ) = sn ⁡ ( u ) cn ⁡ ( u ) , sd ⁡ ( u ) = sn ⁡ ( u ) dn ⁡ ( u ) , dc ⁡ ( u ) = dn ⁡ ( u ) cn ⁡ ( u ) , ds ⁡ ( u ) = dn ⁡ ( u ) sn ⁡ ( u ) , cs ⁡ ( u ) = cn ⁡ ( u ) sn ⁡ ( u ) , cd ⁡ ( u ) = cn ⁡ ( u ) dn ⁡ ( u ) . {\displaystyle {\begin{aligned}\operatorname {sc} (u)={\frac {\operatorname {sn} (u)}{\operatorname {cn} (u)}},\qquad \operatorname {sd} (u)={\frac {\operatorname {sn} (u)}{\operatorname {dn} (u)}},\qquad \operatorname {dc} (u)={\frac {\operatorname {dn} (u)}{\operatorname {cn} (u)}},\qquad \operatorname {ds} (u)={\frac {\operatorname {dn} (u)}{\operatorname {sn} (u)}},\qquad \operatorname {cs} (u)={\frac {\operatorname {cn} (u)}{\operatorname {sn} (u)}},\qquad \operatorname {cd} (u)={\frac {\operatorname {cn} (u)}{\operatorname {dn} (u)}}.\end{aligned}}} More compactly, we have pq ⁡ ( u ) = pn ⁡ ( u ) qn ⁡ ( u ) {\displaystyle \operatorname {pq} (u)={\frac {\operatorname {pn} (u)}{\operatorname {qn} (u)}}} where p and q are any of the letters s, c, d. == Periodicity, poles, and residues == In the complex plane of the argument u, the Jacobi elliptic functions form a repeating pattern of poles (and zeroes). The residues of the poles all have the same absolute value, differing only in sign. Each function pq(u,m) has an "inverse function" (in the multiplicative sense) qp(u,m) in which the positions of the poles and zeroes are exchanged. The periods of repetition are generally different in the real and imaginary directions, hence the use of the term "doubly periodic" to describe them. For the Jacobi amplitude and the Jacobi epsilon function: am ⁡ ( u + 2 K , m ) = am ⁡ ( u , m ) + π , {\displaystyle \operatorname {am} (u+2K,m)=\operatorname {am} (u,m)+\pi ,} am ⁡ ( u + 4 i K ′ , m ) = am ⁡ ( u , m ) , {\displaystyle \operatorname {am} (u+4iK',m)=\operatorname {am} (u,m),} E ( u + 2 K , m ) = E ( u , m ) + 2 E , {\displaystyle {\mathcal {E}}(u+2K,m)={\mathcal {E}}(u,m)+2E,} E ( u + 2 i K ′ , m ) = E ( u , m ) + 2 i E K ′ K − π i K {\displaystyle {\mathcal {E}}(u+2iK',m)={\mathcal {E}}(u,m)+2iE{\frac {K'}{K}}-{\frac {\pi i}{K}}} where E ( m ) {\displaystyle E(m)} is the complete elliptic integral of the second kind with parameter m {\displaystyle m} . The double periodicity of the Jacobi elliptic functions may be expressed as: pq ⁡ ( u + 2 α K ( m ) + 2 i β K ( 1 − m ) , m ) = ( − 1 ) γ pq ⁡ ( u , m ) {\displaystyle \operatorname {pq} (u+2\alpha K(m)+2i\beta K(1-m)\,,\,m)=(-1)^{\gamma }\operatorname {pq} (u,m)} where α and β are any pair of integers. K(⋅) is the complete elliptic integral of the first kind, also known as the quarter period. The power of negative unity (γ) is given in the following table: When the factor (−1)γ is equal to −1, the equation expresses quasi-periodicity. When it is equal to unity, it expresses full periodicity. It can be seen, for example, that for the entries containing only α when α is even, full periodicity is expressed by the above equation, and the function has full periods of 4K(m) and 2iK(1 − m). Likewise, functions with entries containing only β have full periods of 2K(m) and 4iK(1 − m), while those with α + β have full periods of 4K(m) and 4iK(1 − m). In the diagram on the right, which plots one repeating unit for each function, indicating phase along with the location of poles and zeroes, a number of regularities can be noted: The inverse of each function is opposite the diagonal, and has the same size unit cell, with poles and zeroes exchanged. The pole and zero arrangement in the auxiliary rectangle formed by (0,0), (K,0), (0,K′) and (K,K′) are in accordance with the description of the pole and zero placement described in the introduction above. Also, the size of the white ovals indicating poles are a rough measure of the absolute value of the residue for that pole. The residues of the poles closest to the origin in the figure (i.e. in the auxiliary rectangle) are listed in the following table: When applicable, poles displaced above by 2K or displaced to the right by 2K′ have the same value but with signs reversed, while those diagonally opposite have the same value. Note that poles and zeroes on the left and lower edges are considered part of the unit cell, while those on the upper and right edges are not. == Special values == Setting m = − 1 {\displaystyle m=-1} gives the lemniscate elliptic functions sl {\displaystyle \operatorname {sl} } and cl {\displaystyle \operatorname {cl} } : sl ⁡ u = sn ⁡ ( u , − 1 ) , cl ⁡ u = cd ⁡ ( u , − 1 ) = cn ⁡ ( u , − 1 ) dn ⁡ ( u , − 1 ) . {\displaystyle \operatorname {sl} u=\operatorname {sn} (u,-1),\quad \operatorname {cl} u=\operatorname {cd} (u,-1)={\frac {\operatorname {cn} (u,-1)}{\operatorname {dn} (u,-1)}}.} When m = 0 {\displaystyle m=0} or m = 1 {\displaystyle m=1} , the Jacobi elliptic functions are reduced to non-elliptic functions: For the Jacobi amplitude, am ⁡ ( u , 0 ) = u {\displaystyle \operatorname {am} (u,0)=u} and am ⁡ ( u , 1 ) = gd ⁡ u {\displaystyle \operatorname {am} (u,1)=\operatorname {gd} u} where gd {\displaystyle \operatorname {gd} } is the Gudermannian function. In general if neither of p,q is d then pq ⁡ ( u , 1 ) = pq ⁡ ( gd ⁡ ( u ) , 0 ) {\displaystyle \operatorname {pq} (u,1)=\operatorname {pq} (\operatorname {gd} (u),0)} . == Identities == === Half Angle formula === sn ⁡ ( u 2 , m ) = ± 1 − cn ⁡ ( u , m ) 1 + dn ⁡ ( u , m ) {\displaystyle \operatorname {sn} \left({\frac {u}{2}},m\right)=\pm {\sqrt {\frac {1-\operatorname {cn} (u,m)}{1+\operatorname {dn} (u,m)}}}} cn ⁡ ( u 2 , m ) = ± cn ⁡ ( u , m ) + dn ⁡ ( u , m ) 1 + dn ⁡ ( u , m ) {\displaystyle \operatorname {cn} \left({\frac {u}{2}},m\right)=\pm {\sqrt {\frac {\operatorname {cn} (u,m)+\operatorname {dn} (u,m)}{1+\operatorname {dn} (u,m)}}}} cn ⁡ ( u 2 , m ) = ± m ′ + dn ⁡ ( u , m ) + m cn ⁡ ( u , m ) 1 + dn ⁡ ( u , m ) {\displaystyle \operatorname {cn} \left({\frac {u}{2}},m\right)=\pm {\sqrt {\frac {m'+\operatorname {dn} (u,m)+m\operatorname {cn} (u,m)}{1+\operatorname {dn} (u,m)}}}} === K formulas === Half K formula sn ⁡ [ 1 2 K ( k ) ; k ] = 2 1 + k + 1 − k {\displaystyle \operatorname {sn} \left[{\tfrac {1}{2}}K(k);k\right]={\frac {\sqrt {2}}{{\sqrt {1+k}}+{\sqrt {1-k}}}}} cn ⁡ [ 1 2 K ( k ) ; k ] = 2 1 − k 2 4 1 + k + 1 − k {\displaystyle \operatorname {cn} \left[{\tfrac {1}{2}}K(k);k\right]={\frac {{\sqrt {2}}\,{\sqrt[{4}]{1-k^{2}}}}{{\sqrt {1+k}}+{\sqrt {1-k}}}}} dn ⁡ [ 1 2 K ( k ) ; k ] = 1 − k 2 4 {\displaystyle \operatorname {dn} \left[{\tfrac {1}{2}}K(k);k\right]={\sqrt[{4}]{1-k^{2}}}} Third K formula sn ⁡ [ 1 3 K ( x 3 x 6 + 1 + 1 ) ; x 3 x 6 + 1 + 1 ] = 2 x 4 − x 2 + 1 − x 2 + 2 + x 2 + 1 − 1 2 x 4 − x 2 + 1 − x 2 + 2 + x 2 + 1 + 1 {\displaystyle \operatorname {sn} \left[{\frac {1}{3}}K\left({\frac {x^{3}}{{\sqrt {x^{6}+1}}+1}}\right);{\frac {x^{3}}{{\sqrt {x^{6}+1}}+1}}\right]={\frac {{\sqrt {2{\sqrt {x^{4}-x^{2}+1}}-x^{2}+2}}+{\sqrt {x^{2}+1}}-1}{{\sqrt {2{\sqrt {x^{4}-x^{2}+1}}-x^{2}+2}}+{\sqrt {x^{2}+1}}+1}}} To get x3, we take the tangent of twice the arctangent of the modulus. Also this equation leads to the sn-value of the third of K: k 2 s 4 − 2 k 2 s 3 + 2 s − 1 = 0 {\displaystyle k^{2}s^{4}-2k^{2}s^{3}+2s-1=0} s = sn ⁡ [ 1 3 K ( k ) ; k ] {\displaystyle s=\operatorname {sn} \left[{\tfrac {1}{3}}K(k);k\right]} These equations lead to the other values of the Jacobi-Functions: cn ⁡ [ 2 3 K ( k ) ; k ] = 1 − sn ⁡ [ 1 3 K ( k ) ; k ] {\displaystyle \operatorname {cn} \left[{\tfrac {2}{3}}K(k);k\right]=1-\operatorname {sn} \left[{\tfrac {1}{3}}K(k);k\right]} dn ⁡ [ 2 3 K ( k ) ; k ] = 1 / sn ⁡ [ 1 3 K ( k ) ; k ] − 1 {\displaystyle \operatorname {dn} \left[{\tfrac {2}{3}}K(k);k\right]=1/\operatorname {sn} \left[{\tfrac {1}{3}}K(k);k\right]-1} Fifth K formula Following equation has following solution: 4 k 2 x 6 + 8 k 2 x 5 + 2 ( 1 − k 2 ) 2 x − ( 1 − k 2 ) 2 = 0 {\displaystyle 4k^{2}x^{6}+8k^{2}x^{5}+2(1-k^{2})^{2}x-(1-k^{2})^{2}=0} x = 1 2 − 1 2 k 2 sn ⁡ [ 2 5 K ( k ) ; k ] 2 sn ⁡ [ 4 5 K ( k ) ; k ] 2 = sn ⁡ [ 4 5 K ( k ) ; k ] 2 − sn ⁡ [ 2 5 K ( k ) ; k ] 2 2 sn ⁡ [ 2 5 K ( k ) ; k ] sn ⁡ [ 4 5 K ( k ) ; k ] {\displaystyle x={\frac {1}{2}}-{\frac {1}{2}}k^{2}\operatorname {sn} \left[{\tfrac {2}{5}}K(k);k\right]^{2}\operatorname {sn} \left[{\tfrac {4}{5}}K(k);k\right]^{2}={\frac {\operatorname {sn} \left[{\frac {4}{5}}K(k);k\right]^{2}-\operatorname {sn} \left[{\frac {2}{5}}K(k);k\right]^{2}}{2\operatorname {sn} \left[{\frac {2}{5}}K(k);k\right]\operatorname {sn} \left[{\frac {4}{5}}K(k);k\right]}}} To get the sn-values, we put the solution x into following expressions: sn ⁡ [ 2 5 K ( k ) ; k ] = ( 1 + k 2 ) − 1 / 2 2 ( 1 − x − x 2 ) ( x 2 + 1 − x x 2 + 1 ) {\displaystyle \operatorname {sn} \left[{\tfrac {2}{5}}K(k);k\right]=(1+k^{2})^{-1/2}{\sqrt {2(1-x-x^{2})(x^{2}+1-x{\sqrt {x^{2}+1}})}}} sn ⁡ [ 4 5 K ( k ) ; k ] = ( 1 + k 2 ) − 1 / 2 2 ( 1 − x − x 2 ) ( x 2 + 1 + x x 2 + 1 ) {\displaystyle \operatorname {sn} \left[{\tfrac {4}{5}}K(k);k\right]=(1+k^{2})^{-1/2}{\sqrt {2(1-x-x^{2})(x^{2}+1+x{\sqrt {x^{2}+1}})}}} === Relations between squares of the functions === Relations between squares of the functions can be derived from two basic relationships (Arguments (u,m) suppressed): cn 2 + sn 2 = 1 {\displaystyle \operatorname {cn} ^{2}+\operatorname {sn} ^{2}=1} cn 2 + m ′ sn 2 = dn 2 {\displaystyle \operatorname {cn} ^{2}+m'\operatorname {sn} ^{2}=\operatorname {dn} ^{2}} where m + m' = 1. Multiplying by any function of the form nq yields more general equations: cq 2 + sq 2 = nq 2 {\displaystyle \operatorname {cq} ^{2}+\operatorname {sq} ^{2}=\operatorname {nq} ^{2}} cq 2 ⁡ + m ′ sq 2 = dq 2 {\displaystyle \operatorname {cq} ^{2}{}+m'\operatorname {sq} ^{2}=\operatorname {dq} ^{2}} With q = d, these correspond trigonometrically to the equations for the unit circle ( x 2 + y 2 = r 2 {\displaystyle x^{2}+y^{2}=r^{2}} ) and the unit ellipse ( x 2 + m ′ y 2 = 1 {\displaystyle x^{2}{}+m'y^{2}=1} ), with x = cd, y = sd and r = nd. Using the multiplication rule, other relationships may be derived. For example: − dn 2 ⁡ + m ′ = − m cn 2 = m sn 2 − m {\displaystyle -\operatorname {dn} ^{2}{}+m'=-m\operatorname {cn} ^{2}=m\operatorname {sn} ^{2}-m} − m ′ nd 2 ⁡ + m ′ = − m m ′ sd 2 = m cd 2 − m {\displaystyle -m'\operatorname {nd} ^{2}{}+m'=-mm'\operatorname {sd} ^{2}=m\operatorname {cd} ^{2}-m} m ′ sc 2 ⁡ + m ′ = m ′ nc 2 = dc 2 − m {\displaystyle m'\operatorname {sc} ^{2}{}+m'=m'\operatorname {nc} ^{2}=\operatorname {dc} ^{2}-m} cs 2 ⁡ + m ′ = ds 2 = ns 2 − m {\displaystyle \operatorname {cs} ^{2}{}+m'=\operatorname {ds} ^{2}=\operatorname {ns} ^{2}-m} === Addition theorems === The functions satisfy the two square relations (dependence on m suppressed) cn 2 ⁡ ( u ) + sn 2 ⁡ ( u ) = 1 , {\displaystyle \operatorname {cn} ^{2}(u)+\operatorname {sn} ^{2}(u)=1,\,} dn 2 ⁡ ( u ) + m sn 2 ⁡ ( u ) = 1. {\displaystyle \operatorname {dn} ^{2}(u)+m\operatorname {sn} ^{2}(u)=1.\,} From this we see that (cn, sn, dn) parametrizes an elliptic curve which is the intersection of the two quadrics defined by the above two equations. We now may define a group law for points on this curve by the addition formulas for the Jacobi functions cn ⁡ ( x + y ) = cn ⁡ ( x ) cn ⁡ ( y ) − sn ⁡ ( x ) sn ⁡ ( y ) dn ⁡ ( x ) dn ⁡ ( y ) 1 − m sn 2 ⁡ ( x ) sn 2 ⁡ ( y ) , sn ⁡ ( x + y ) = sn ⁡ ( x ) cn ⁡ ( y ) dn ⁡ ( y ) + sn ⁡ ( y ) cn ⁡ ( x ) dn ⁡ ( x ) 1 − m sn 2 ⁡ ( x ) sn 2 ⁡ ( y ) , dn ⁡ ( x + y ) = dn ⁡ ( x ) dn ⁡ ( y ) − m sn ⁡ ( x ) sn ⁡ ( y ) cn ⁡ ( x ) cn ⁡ ( y ) 1 − m sn 2 ⁡ ( x ) sn 2 ⁡ ( y ) . {\displaystyle {\begin{aligned}\operatorname {cn} (x+y)&={\operatorname {cn} (x)\operatorname {cn} (y)-\operatorname {sn} (x)\operatorname {sn} (y)\operatorname {dn} (x)\operatorname {dn} (y) \over {1-m\operatorname {sn} ^{2}(x)\operatorname {sn} ^{2}(y)}},\\[8pt]\operatorname {sn} (x+y)&={\operatorname {sn} (x)\operatorname {cn} (y)\operatorname {dn} (y)+\operatorname {sn} (y)\operatorname {cn} (x)\operatorname {dn} (x) \over {1-m\operatorname {sn} ^{2}(x)\operatorname {sn} ^{2}(y)}},\\[8pt]\operatorname {dn} (x+y)&={\operatorname {dn} (x)\operatorname {dn} (y)-m\operatorname {sn} (x)\operatorname {sn} (y)\operatorname {cn} (x)\operatorname {cn} (y) \over {1-m\operatorname {sn} ^{2}(x)\operatorname {sn} ^{2}(y)}}.\end{aligned}}} The Jacobi epsilon and zn functions satisfy a quasi-addition theorem: E ( x + y , m ) = E ( x , m ) + E ( y , m ) − m sn ⁡ ( x , m ) sn ⁡ ( y , m ) sn ⁡ ( x + y , m ) , zn ⁡ ( x + y , m ) = zn ⁡ ( x , m ) + zn ⁡ ( y , m ) − m sn ⁡ ( x , m ) sn ⁡ ( y , m ) sn ⁡ ( x + y , m ) . {\displaystyle {\begin{aligned}{\mathcal {E}}(x+y,m)&={\mathcal {E}}(x,m)+{\mathcal {E}}(y,m)-m\operatorname {sn} (x,m)\operatorname {sn} (y,m)\operatorname {sn} (x+y,m),\\\operatorname {zn} (x+y,m)&=\operatorname {zn} (x,m)+\operatorname {zn} (y,m)-m\operatorname {sn} (x,m)\operatorname {sn} (y,m)\operatorname {sn} (x+y,m).\end{aligned}}} Double angle formulae can be easily derived from the above equations by setting x = y. Half angle formulae are all of the form: pq ⁡ ( 1 2 u , m ) 2 = f p / f q {\displaystyle \operatorname {pq} ({\tfrac {1}{2}}u,m)^{2}=f_{\mathrm {p} }/f_{\mathrm {q} }} where: f c = cn ⁡ ( u , m ) + dn ⁡ ( u , m ) {\displaystyle f_{\mathrm {c} }=\operatorname {cn} (u,m)+\operatorname {dn} (u,m)} f s = 1 − cn ⁡ ( u , m ) {\displaystyle f_{\mathrm {s} }=1-\operatorname {cn} (u,m)} f n = 1 + dn ⁡ ( u , m ) {\displaystyle f_{\mathrm {n} }=1+\operatorname {dn} (u,m)} f d = ( 1 + dn ⁡ ( u , m ) ) − m ( 1 − cn ⁡ ( u , m ) ) {\displaystyle f_{\mathrm {d} }=(1+\operatorname {dn} (u,m))-m(1-\operatorname {cn} (u,m))} == Jacobi elliptic functions as solutions of nonlinear ordinary differential equations == === Derivatives with respect to the first variable === The derivatives of the three basic Jacobi elliptic functions (with respect to the first variable, with m {\displaystyle m} fixed) are: d d z sn ⁡ ( z ) = cn ⁡ ( z ) dn ⁡ ( z ) , {\displaystyle {\frac {\mathrm {d} }{\mathrm {d} z}}\operatorname {sn} (z)=\operatorname {cn} (z)\operatorname {dn} (z),} d d z cn ⁡ ( z ) = − sn ⁡ ( z ) dn ⁡ ( z ) , {\displaystyle {\frac {\mathrm {d} }{\mathrm {d} z}}\operatorname {cn} (z)=-\operatorname {sn} (z)\operatorname {dn} (z),} d d z dn ⁡ ( z ) = − m sn ⁡ ( z ) cn ⁡ ( z ) . {\displaystyle {\frac {\mathrm {d} }{\mathrm {d} z}}\operatorname {dn} (z)=-m\operatorname {sn} (z)\operatorname {cn} (z).} These can be used to derive the derivatives of all other functions as shown in the table below (arguments (u,m) suppressed): Also d d z E ( z ) = dn ⁡ ( z ) 2 . {\displaystyle {\frac {\mathrm {d} }{\mathrm {d} z}}{\mathcal {E}}(z)=\operatorname {dn} (z)^{2}.} With the addition theorems above and for a given m with 0 < m < 1 the major functions are therefore solutions to the following nonlinear ordinary differential equations: sn ⁡ ( x ) {\displaystyle \operatorname {sn} (x)} solves the differential equations d 2 y d x 2 + ( 1 + m ) y − 2 m y 3 = 0 {\displaystyle {\frac {\mathrm {d} ^{2}y}{\mathrm {d} x^{2}}}+(1+m)y-2my^{3}=0} and ( d y d x ) 2 = ( 1 − y 2 ) ( 1 − m y 2 ) {\displaystyle \left({\frac {\mathrm {d} y}{\mathrm {d} x}}\right)^{2}=(1-y^{2})(1-my^{2})} cn ⁡ ( x ) {\displaystyle \operatorname {cn} (x)} solves the differential equations d 2 y d x 2 + ( 1 − 2 m ) y + 2 m y 3 = 0 {\displaystyle {\frac {\mathrm {d} ^{2}y}{\mathrm {d} x^{2}}}+(1-2m)y+2my^{3}=0} and ( d y d x ) 2 = ( 1 − y 2 ) ( 1 − m + m y 2 ) {\displaystyle \left({\frac {\mathrm {d} y}{\mathrm {d} x}}\right)^{2}=(1-y^{2})(1-m+my^{2})} dn ⁡ ( x ) {\displaystyle \operatorname {dn} (x)} solves the differential equations d 2 y d x 2 − ( 2 − m ) y + 2 y 3 = 0 {\displaystyle {\frac {\mathrm {d} ^{2}y}{\mathrm {d} x^{2}}}-(2-m)y+2y^{3}=0} and ( d y d x ) 2 = ( y 2 − 1 ) ( 1 − m − y 2 ) {\displaystyle \left({\frac {\mathrm {d} y}{\mathrm {d} x}}\right)^{2}=(y^{2}-1)(1-m-y^{2})} The function which exactly solves the pendulum differential equation, d 2 θ d t 2 + c sin ⁡ θ = 0 , {\displaystyle {\frac {\mathrm {d} ^{2}\theta }{\mathrm {d} t^{2}}}+c\sin \theta =0,} with initial angle θ 0 {\displaystyle \theta _{0}} and zero initial angular velocity is θ = 2 arcsin ⁡ ( m cd ⁡ ( c t , m ) ) = 2 am ⁡ ( 1 + m 2 ( c t + K ) , 4 m ( 1 + m ) 2 ) − 2 am ⁡ ( 1 + m 2 ( c t − K ) , 4 m ( 1 + m ) 2 ) − π {\displaystyle {\begin{aligned}\theta &=2\arcsin({\sqrt {m}}\operatorname {cd} ({\sqrt {c}}t,m))\\&=2\operatorname {am} \left({\frac {1+{\sqrt {m}}}{2}}({\sqrt {c}}t+K),{\frac {4{\sqrt {m}}}{(1+{\sqrt {m}})^{2}}}\right)-2\operatorname {am} \left({\frac {1+{\sqrt {m}}}{2}}({\sqrt {c}}t-K),{\frac {4{\sqrt {m}}}{(1+{\sqrt {m}})^{2}}}\right)-\pi \end{aligned}}} where m = sin ⁡ ( θ 0 / 2 ) 2 {\displaystyle m=\sin(\theta _{0}/2)^{2}} , c > 0 {\displaystyle c>0} and t ∈ R {\displaystyle t\in \mathbb {R} } . === Derivatives with respect to the second variable === With the first argument z {\displaystyle z} fixed, the derivatives with respect to the second variable m {\displaystyle m} are as follows: d d m sn ⁡ ( z ) = dn ⁡ ( z ) cn ⁡ ( z ) ( ( 1 − m ) z − E ( z ) + m cd ⁡ ( z ) sn ⁡ ( z ) ) 2 m ( 1 − m ) , d d m cn ⁡ ( z ) = sn ⁡ ( z ) dn ⁡ ( z ) ( ( m − 1 ) z + E ( z ) − m sn ⁡ ( z ) cd ⁡ ( z ) ) 2 m ( 1 − m ) , d d m dn ⁡ ( z ) = sn ⁡ ( z ) cn ⁡ ( z ) ( ( m − 1 ) z + E ( z ) − dn ⁡ ( z ) sc ⁡ ( z ) ) 2 ( 1 − m ) , d d m E ( z ) = cn ⁡ ( z ) ( sn ⁡ ( z ) dn ⁡ ( z ) − cn ⁡ ( z ) E ( z ) ) 2 ( 1 − m ) − z 2 sn ⁡ ( z ) 2 . {\displaystyle {\begin{aligned}{\frac {\mathrm {d} }{\mathrm {d} m}}\operatorname {sn} (z)&={\frac {\operatorname {dn} (z)\operatorname {cn} (z)((1-m)z-{\mathcal {E}}(z)+m\operatorname {cd} (z)\operatorname {sn} (z))}{2m(1-m)}},\\{\frac {\mathrm {d} }{\mathrm {d} m}}\operatorname {cn} (z)&={\frac {\operatorname {sn} (z)\operatorname {dn} (z)((m-1)z+{\mathcal {E}}(z)-m\operatorname {sn} (z)\operatorname {cd} (z))}{2m(1-m)}},\\{\frac {\mathrm {d} }{\mathrm {d} m}}\operatorname {dn} (z)&={\frac {\operatorname {sn} (z)\operatorname {cn} (z)((m-1)z+{\mathcal {E}}(z)-\operatorname {dn} (z)\operatorname {sc} (z))}{2(1-m)}},\\{\frac {\mathrm {d} }{\mathrm {d} m}}{\mathcal {E}}(z)&={\frac {\operatorname {cn} (z)(\operatorname {sn} (z)\operatorname {dn} (z)-\operatorname {cn} (z){\mathcal {E}}(z))}{2(1-m)}}-{\frac {z}{2}}\operatorname {sn} (z)^{2}.\end{aligned}}} == Expansion in terms of the nome == Let the nome be q = exp ⁡ ( − π K ′ ( m ) / K ( m ) ) = e i π τ {\displaystyle q=\exp(-\pi K'(m)/K(m))=e^{i\pi \tau }} , Im ⁡ ( τ ) > 0 {\displaystyle \operatorname {Im} (\tau )>0} , m = k 2 {\displaystyle m=k^{2}} and let v = π u / ( 2 K ( m ) ) {\displaystyle v=\pi u/(2K(m))} . Then the functions have expansions as Lambert series am ⁡ ( u , m ) = π u 2 K ( m ) + 2 ∑ n = 1 ∞ q n n ( 1 + q 2 n ) sin ⁡ ( 2 n v ) , {\displaystyle \operatorname {am} (u,m)={\frac {\pi u}{2K(m)}}+2\sum _{n=1}^{\infty }{\frac {q^{n}}{n(1+q^{2n})}}\sin(2nv),} sn ⁡ ( u , m ) = 2 π k K ( m ) ∑ n = 0 ∞ q n + 1 / 2 1 − q 2 n + 1 sin ⁡ ( ( 2 n + 1 ) v ) , {\displaystyle \operatorname {sn} (u,m)={\frac {2\pi }{kK(m)}}\sum _{n=0}^{\infty }{\frac {q^{n+1/2}}{1-q^{2n+1}}}\sin((2n+1)v),} cn ⁡ ( u , m ) = 2 π k K ( m ) ∑ n = 0 ∞ q n + 1 / 2 1 + q 2 n + 1 cos ⁡ ( ( 2 n + 1 ) v ) , {\displaystyle \operatorname {cn} (u,m)={\frac {2\pi }{kK(m)}}\sum _{n=0}^{\infty }{\frac {q^{n+1/2}}{1+q^{2n+1}}}\cos((2n+1)v),} dn ⁡ ( u , m ) = π 2 K ( m ) + 2 π K ( m ) ∑ n = 1 ∞ q n 1 + q 2 n cos ⁡ ( 2 n v ) , {\displaystyle \operatorname {dn} (u,m)={\frac {\pi }{2K(m)}}+{\frac {2\pi }{K(m)}}\sum _{n=1}^{\infty }{\frac {q^{n}}{1+q^{2n}}}\cos(2nv),} zn ⁡ ( u , m ) = 2 π K ( m ) ∑ n = 1 ∞ q n 1 − q 2 n sin ⁡ ( 2 n v ) {\displaystyle \operatorname {zn} (u,m)={\frac {2\pi }{K(m)}}\sum _{n=1}^{\infty }{\frac {q^{n}}{1-q^{2n}}}\sin(2nv)} when | Im ⁡ ( u / K ) | < Im ⁡ ( i K ′ / K ) . {\displaystyle \left|\operatorname {Im} (u/K)\right|<\operatorname {Im} (iK'/K).} Bivariate power series expansions have been published by Schett. == Fast computation == The theta function ratios provide an efficient way of computing the Jacobi elliptic functions. There is an alternative method, based on the arithmetic-geometric mean and Landen's transformations: Initialize a 0 = 1 , b 0 = 1 − m {\displaystyle a_{0}=1,\,b_{0}={\sqrt {1-m}}} where 0 < m < 1 {\displaystyle 0<m<1} . Define a n = a n − 1 + b n − 1 2 , b n = a n − 1 b n − 1 , c n = a n − 1 − b n − 1 2 {\displaystyle a_{n}={\frac {a_{n-1}+b_{n-1}}{2}},\,b_{n}={\sqrt {a_{n-1}b_{n-1}}},\,c_{n}={\frac {a_{n-1}-b_{n-1}}{2}}} where n ≥ 1 {\displaystyle n\geq 1} . Then define φ N = 2 N a N u {\displaystyle \varphi _{N}=2^{N}a_{N}u} for u ∈ R {\displaystyle u\in \mathbb {R} } and a fixed N ∈ N {\displaystyle N\in \mathbb {N} } . If φ n − 1 = 1 2 ( φ n + arcsin ⁡ ( c n a n sin ⁡ φ n ) ) {\displaystyle \varphi _{n-1}={\frac {1}{2}}\left(\varphi _{n}+\arcsin \left({\frac {c_{n}}{a_{n}}}\sin \varphi _{n}\right)\right)} for n ≥ 1 {\displaystyle n\geq 1} , then am ⁡ ( u , m ) = φ 0 , zn ⁡ ( u , m ) = ∑ n = 1 N c n sin ⁡ φ n {\displaystyle \operatorname {am} (u,m)=\varphi _{0},\quad \operatorname {zn} (u,m)=\sum _{n=1}^{N}c_{n}\sin \varphi _{n}} as N → ∞ {\displaystyle N\to \infty } . This is notable for its rapid convergence. It is then trivial to compute all Jacobi elliptic functions from the Jacobi amplitude am {\displaystyle \operatorname {am} } on the real line. In conjunction with the addition theorems for elliptic functions (which hold for complex numbers in general) and the Jacobi transformations, the method of computation described above can be used to compute all Jacobi elliptic functions in the whole complex plane. Another method of fast computation of the Jacobi elliptic functions via the arithmetic–geometric mean, avoiding the computation of the Jacobi amplitude, is due to Herbert E. Salzer: Let 0 ≤ m ≤ 1 , 0 ≤ u ≤ K ( m ) , a 0 = 1 , b 0 = 1 − m , {\displaystyle 0\leq m\leq 1,\,0\leq u\leq K(m),\,a_{0}=1,\,b_{0}={\sqrt {1-m}},} a n + 1 = a n + b n 2 , b n + 1 = a n b n , c n + 1 = a n − b n 2 . {\displaystyle a_{n+1}={\frac {a_{n}+b_{n}}{2}},\,b_{n+1}={\sqrt {a_{n}b_{n}}},\,c_{n+1}={\frac {a_{n}-b_{n}}{2}}.} Set y N = a N sin ⁡ ( a N u ) y N − 1 = y N + a N c N y N y N − 2 = y N − 1 + a N − 1 c N − 1 y N − 1 ⋮ = ⋮ y 0 = y 1 + m 4 y 1 . {\displaystyle {\begin{aligned}y_{N}&={\frac {a_{N}}{\sin(a_{N}u)}}\\y_{N-1}&=y_{N}+{\frac {a_{N}c_{N}}{y_{N}}}\\y_{N-2}&=y_{N-1}+{\frac {a_{N-1}c_{N-1}}{y_{N-1}}}\\\vdots &=\vdots \\y_{0}&=y_{1}+{\frac {m}{4y_{1}}}.\end{aligned}}} Then sn ⁡ ( u , m ) = 1 y 0 cn ⁡ ( u , m ) = 1 − 1 y 0 2 dn ⁡ ( u , m ) = 1 − m y 0 2 {\displaystyle {\begin{aligned}\operatorname {sn} (u,m)&={\frac {1}{y_{0}}}\\\operatorname {cn} (u,m)&={\sqrt {1-{\frac {1}{y_{0}^{2}}}}}\\\operatorname {dn} (u,m)&={\sqrt {1-{\frac {m}{y_{0}^{2}}}}}\end{aligned}}} as N → ∞ {\displaystyle N\to \infty } . == Approximation in terms of hyperbolic functions == The Jacobi elliptic functions can be expanded in terms of the hyperbolic functions. When m {\displaystyle m} is close to unity, such that m ′ 2 {\displaystyle m'^{2}} and higher powers of m ′ {\displaystyle m'} can be neglected, we have: sn(u): sn ⁡ ( u , m ) ≈ tanh ⁡ ( u ) + 1 4 m ′ ( sinh ⁡ ( u ) cosh ⁡ ( u ) − u ) sech 2 ⁡ ( u ) . {\displaystyle \operatorname {sn} (u,m)\approx \tanh(u)+{\frac {1}{4}}m'(\sinh(u)\cosh(u)-u)\operatorname {sech} ^{2}(u).} cn(u): cn ⁡ ( u , m ) ≈ sech ⁡ ( u ) − 1 4 m ′ ( sinh ⁡ ( u ) cosh ⁡ ( u ) − u ) tanh ⁡ ( u ) sech ⁡ ( u ) . {\displaystyle \operatorname {cn} (u,m)\approx \operatorname {sech} (u)-{\frac {1}{4}}m'(\sinh(u)\cosh(u)-u)\tanh(u)\operatorname {sech} (u).} dn(u): dn ⁡ ( u , m ) ≈ sech ⁡ ( u ) + 1 4 m ′ ( sinh ⁡ ( u ) cosh ⁡ ( u ) + u ) tanh ⁡ ( u ) sech ⁡ ( u ) . {\displaystyle \operatorname {dn} (u,m)\approx \operatorname {sech} (u)+{\frac {1}{4}}m'(\sinh(u)\cosh(u)+u)\tanh(u)\operatorname {sech} (u).} For the Jacobi amplitude, am ⁡ ( u , m ) ≈ gd ⁡ ( u ) + 1 4 m ′ ( sinh ⁡ ( u ) cosh ⁡ ( u ) − u ) sech ⁡ ( u ) . {\displaystyle \operatorname {am} (u,m)\approx \operatorname {gd} (u)+{\frac {1}{4}}m'(\sinh(u)\cosh(u)-u)\operatorname {sech} (u).} == Continued fractions == Assuming real numbers a , p {\displaystyle a,p} with 0 < a < p {\displaystyle 0<a<p} and the nome q = e π i τ {\displaystyle q=e^{\pi i\tau }} , Im ⁡ ( τ ) > 0 {\displaystyle \operatorname {Im} (\tau )>0} with elliptic modulus k ( τ ) = 1 − k ′ ( τ ) 2 = ( ϑ 10 ( 0 ; τ ) / ϑ 00 ( 0 ; τ ) ) 2 {\textstyle k(\tau )={\sqrt {1-k'(\tau )^{2}}}=(\vartheta _{10}(0;\tau )/\vartheta _{00}(0;\tau ))^{2}} . If K [ τ ] = K ( k ( τ ) ) {\displaystyle K[\tau ]=K(k(\tau ))} , where K ( x ) = π / 2 ⋅ 2 F 1 ( 1 / 2 , 1 / 2 ; 1 ; x 2 ) {\displaystyle K(x)=\pi /2\cdot {}_{2}F_{1}(1/2,1/2;1;x^{2})} is the complete elliptic integral of the first kind, then holds the following continued fraction expansion dn ( ( p / 2 − a ) τ K [ p τ 2 ] ; k ( p τ 2 ) ) k ′ ( p τ 2 ) = ∑ n = − ∞ ∞ q p / 2 n 2 + ( p / 2 − a ) n ∑ n = − ∞ ∞ ( − 1 ) n q p / 2 n 2 + ( p / 2 − a ) n = − 1 + 2 1 − q a + q p − a 1 − q p + ( q a + q 2 p − a ) ( q a + p + q p − a ) 1 − q 3 p + q p ( q a + q 3 p − a ) ( q a + 2 p + q p − a ) 1 − q 5 p + q 2 p ( q a + q 4 p − a ) ( q a + 3 p + q p − a ) 1 − q 7 p + ⋯ {\displaystyle {\begin{aligned}&{\frac {{\textrm {dn}}\left((p/2-a)\tau K\left[{\frac {p\tau }{2}}\right];k\left({\frac {p\tau }{2}}\right)\right)}{\sqrt {k'\left({\frac {p\tau }{2}}\right)}}}={\frac {\sum _{n=-\infty }^{\infty }q^{p/2n^{2}+(p/2-a)n}}{\sum _{n=-\infty }^{\infty }(-1)^{n}q^{p/2n^{2}+(p/2-a)n}}}\\[4pt]={}&-1+{\frac {2}{1-{}}}\,{\frac {q^{a}+q^{p-a}}{1-q^{p}+{}}}\,{\frac {(q^{a}+q^{2p-a})(q^{a+p}+q^{p-a})}{1-q^{3p}+{}}}\,{\frac {q^{p}(q^{a}+q^{3p-a})(q^{a+2p}+q^{p-a})}{1-q^{5p}+{}}}\,{\frac {q^{2p}(q^{a}+q^{4p-a})(q^{a+3p}+q^{p-a})}{1-q^{7p}+{}}}\cdots \end{aligned}}} Known continued fractions involving sn ( t ) , cn ( t ) {\displaystyle {\textrm {sn}}(t),{\textrm {cn}}(t)} and dn ( t ) {\displaystyle {\textrm {dn}}(t)} with elliptic modulus k {\displaystyle k} are For z ∈ C {\displaystyle z\in \mathbb {C} } , | k | < 1 {\displaystyle |k|<1} : pg. 374 ∫ 0 ∞ sn ( t ) e − t z d t = 1 1 2 ( 1 + k 2 ) + z 2 − 1 ⋅ 2 2 ⋅ 3 k 2 3 2 ( 1 + k 2 ) + z 2 − 3 ⋅ 4 2 ⋅ 5 k 2 5 2 ( 1 + k 2 ) + z 2 − ⋯ {\displaystyle \int _{0}^{\infty }{\textrm {sn}}(t)e^{-tz}\,\mathrm {d} t={\frac {1}{1^{2}(1+k^{2})+z^{2}-{}}}\,{\frac {1\cdot 2^{2}\cdot 3k^{2}}{3^{2}(1+k^{2})+z^{2}-{}}}\,{\frac {3\cdot 4^{2}\cdot 5k^{2}}{5^{2}(1+k^{2})+z^{2}-{}}}\cdots } For z ∈ C ∖ { 0 } {\displaystyle z\in \mathbb {C} \setminus \{0\}} , | k | < 1 {\displaystyle |k|<1} : pg. 375 ∫ 0 ∞ sn 2 ( t ) e − t z d t = 2 z − 1 2 2 ( 1 + k 2 ) + z 2 − 2 ⋅ 3 2 ⋅ 4 k 2 4 2 ( 1 + k 2 ) + z 2 − 4 ⋅ 5 2 ⋅ 6 k 2 6 2 ( 1 + k 2 ) + z 2 − ⋯ {\displaystyle \int _{0}^{\infty }{\textrm {sn}}^{2}(t)e^{-tz}\,\mathrm {d} t={\frac {2z^{-1}}{2^{2}(1+k^{2})+z^{2}-{}}}\,{\frac {2\cdot 3^{2}\cdot 4k^{2}}{4^{2}(1+k^{2})+z^{2}-{}}}\,{\frac {4\cdot 5^{2}\cdot 6k^{2}}{6^{2}(1+k^{2})+z^{2}-{}}}\cdots } For z ∈ C ∖ { 0 } {\displaystyle z\in \mathbb {C} \setminus \{0\}} , | k | < 1 {\displaystyle |k|<1} : pg. 220 ∫ 0 ∞ cn ( t ) e − t z d t = 1 z + 1 2 z + 2 2 k 2 z + 3 2 z + 4 2 k 2 z + 5 2 z + ⋯ {\displaystyle \int _{0}^{\infty }{\textrm {cn}}(t)e^{-tz}\,\mathrm {d} t={\frac {1}{z+{}}}\,{\frac {1^{2}}{z+{}}}\,{\frac {2^{2}k^{2}}{z+{}}}\,{\frac {3^{2}}{z+{}}}\,{\frac {4^{2}k^{2}}{z+{}}}\,{\frac {5^{2}}{z+{}}}\cdots } For z ∈ C ∖ { 0 } {\displaystyle z\in \mathbb {C} \setminus \{0\}} , | k | < 1 {\displaystyle |k|<1} : pg. 374 ∫ 0 ∞ dn ( t ) e − t z d t = 1 z + 1 2 k 2 z + 2 2 z + 3 2 k 2 z + 4 2 z + 5 2 k 2 z + ⋯ {\displaystyle \int _{0}^{\infty }{\textrm {dn}}(t)e^{-tz}\,\mathrm {d} t={\frac {1}{z+{}}}\,{\frac {1^{2}k^{2}}{z+{}}}\,{\frac {2^{2}}{z+{}}}\,{\frac {3^{2}k^{2}}{z+{}}}\,{\frac {4^{2}}{z+{}}}\,{\frac {5^{2}k^{2}}{z+{}}}\cdots } For z ∈ C {\displaystyle z\in \mathbb {C} } , | k | < 1 {\displaystyle |k|<1} : pg. 375 ∫ 0 ∞ sn ( t ) cn ( t ) dn ( t ) e − t z d t = 1 2 ⋅ 1 2 ( 2 − k 2 ) + z 2 − 1 ⋅ 2 2 ⋅ 3 k 4 2 ⋅ 3 2 ( 2 − k 2 ) + z 2 − 3 ⋅ 4 2 ⋅ 5 k 4 2 ⋅ 5 2 ( 2 − k 2 ) + z 2 − ⋯ {\displaystyle \int _{0}^{\infty }{\frac {{\textrm {sn}}(t){\textrm {cn}}(t)}{{\textrm {dn}}(t)}}e^{-tz}\,\mathrm {d} t={\frac {1}{2\cdot 1^{2}(2-k^{2})+z^{2}-{}}}\,{\frac {1\cdot 2^{2}\cdot 3k^{4}}{2\cdot 3^{2}(2-k^{2})+z^{2}-{}}}\,{\frac {3\cdot 4^{2}\cdot 5k^{4}}{2\cdot 5^{2}(2-k^{2})+z^{2}-{}}}\cdots } == Inverse functions == The inverses of the Jacobi elliptic functions can be defined similarly to the inverse trigonometric functions; if x = sn ⁡ ( ξ , m ) {\displaystyle x=\operatorname {sn} (\xi ,m)} , ξ = arcsn ⁡ ( x , m ) {\displaystyle \xi =\operatorname {arcsn} (x,m)} . They can be represented as elliptic integrals, and power series representations have been found. arcsn ⁡ ( x , m ) = ∫ 0 x d t ( 1 − t 2 ) ( 1 − m t 2 ) {\displaystyle \operatorname {arcsn} (x,m)=\int _{0}^{x}{\frac {\mathrm {d} t}{\sqrt {(1-t^{2})(1-mt^{2})}}}} arccn ⁡ ( x , m ) = ∫ x 1 d t ( 1 − t 2 ) ( 1 − m + m t 2 ) {\displaystyle \operatorname {arccn} (x,m)=\int _{x}^{1}{\frac {\mathrm {d} t}{\sqrt {(1-t^{2})(1-m+mt^{2})}}}} arcdn ⁡ ( x , m ) = ∫ x 1 d t ( 1 − t 2 ) ( t 2 + m − 1 ) {\displaystyle \operatorname {arcdn} (x,m)=\int _{x}^{1}{\frac {\mathrm {d} t}{\sqrt {(1-t^{2})(t^{2}+m-1)}}}} == Map projection == The Peirce quincuncial projection is a map projection based on Jacobian elliptic functions. == See also == Elliptic curve Schwarz–Christoffel mapping Carlson symmetric form Jacobi theta function Ramanujan theta function Dixon elliptic functions Abel elliptic functions Weierstrass elliptic function Lemniscate elliptic functions == Notes == == Citations == == References == Abramowitz, Milton; Stegun, Irene Ann, eds. (1983) [June 1964]. "Chapter 16". Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables. Applied Mathematics Series. Vol. 55 (Ninth reprint with additional corrections of tenth original printing with corrections (December 1972); first ed.). Washington D.C.; New York: United States Department of Commerce, National Bureau of Standards; Dover Publications. p. 569. ISBN 978-0-486-61272-0. LCCN 64-60036. MR 0167642. LCCN 65-12253. N. I. Akhiezer, Elements of the Theory of Elliptic Functions (1970) Moscow, translated into English as AMS Translations of Mathematical Monographs Volume 79 (1990) AMS, Rhode Island ISBN 0-8218-4532-2 A. C. Dixon The elementary properties of the elliptic functions, with examples (Macmillan, 1894) Alfred George Greenhill The applications of elliptic functions (London, New York, Macmillan, 1892) Edmund T. Whittaker, George Neville Watson: A Course in Modern Analysis. 4th ed. Cambridge, England: Cambridge University Press, 1990. S. 469–470. H. Hancock Lectures on the theory of elliptic functions (New York, J. Wiley & sons, 1910) Jacobi, C. G. J. (1829), Fundamenta nova theoriae functionum ellipticarum (in Latin), Königsberg, ISBN 978-1-108-05200-9, Reprinted by Cambridge University Press 2012 Reinhardt, William P.; Walker, Peter L. (2010), "Jacobian Elliptic Functions", in Olver, Frank W. J.; Lozier, Daniel M.; Boisvert, Ronald F.; Clark, Charles W. (eds.), NIST Handbook of Mathematical Functions, Cambridge University Press, ISBN 978-0-521-19225-5, MR 2723248. (in French) P. Appell and E. Lacour Principes de la théorie des fonctions elliptiques et applications (Paris, Gauthier Villars, 1897) (in French) G. H. Halphen Traité des fonctions elliptiques et de leurs applications (vol. 1) (Paris, Gauthier-Villars, 1886–1891) (in French) G. H. Halphen Traité des fonctions elliptiques et de leurs applications (vol. 2) (Paris, Gauthier-Villars, 1886–1891) (in French) G. H. Halphen Traité des fonctions elliptiques et de leurs applications (vol. 3) (Paris, Gauthier-Villars, 1886–1891) (in French) J. Tannery and J. Molk Eléments de la théorie des fonctions elliptiques. Tome I, Introduction. Calcul différentiel. Ire partie (Paris : Gauthier-Villars et fils, 1893) (in French) J. Tannery and J. Molk Eléments de la théorie des fonctions elliptiques. Tome II, Calcul différentiel. IIe partie (Paris : Gauthier-Villars et fils, 1893) (in French) J. Tannery and J. Molk Eléments de la théorie des fonctions elliptiques. Tome III, Calcul intégral. Ire partie, Théorèmes généraux. Inversion (Paris : Gauthier-Villars et fils, 1893) (in French) J. Tannery and J. Molk Eléments de la théorie des fonctions elliptiques. Tome IV, Calcul intégral. IIe partie, Applications (Paris : Gauthier-Villars et fils, 1893) (in French) C. Briot and J. C. Bouquet Théorie des fonctions elliptiques ( Paris : Gauthier-Villars, 1875) Toshio Fukushima: Fast Computation of Complete Elliptic Integrals and Jacobian Elliptic Functions. 2012, National Astronomical Observatory of Japan (国立天文台) Lowan, Blanch und Horenstein: On the Inversion of the q-Series Associated with Jacobian Elliptic Functions. Bull. Amer. Math. Soc. 48, 1942 H. Ferguson, D. E. Nielsen, G. Cook: A partition formula for the integer coefficients of the theta function nome. Mathematics of computation, Volume 29, Nummer 131, Juli 1975 J. D. Fenton and R. S. Gardiner-Garden: Rapidly-convergent methods for evaluating elliptic integrals and theta and elliptic functions. J. Austral. Math. Soc. (Series B) 24, 1982, S. 57 Adolf Kneser: Neue Untersuchung einer Reihe aus der Theorie der elliptischen Funktionen. J. reine u. angew. Math. 157, 1927. pages 209 – 218 == External links == "Jacobi elliptic functions", Encyclopedia of Mathematics, EMS Press, 2001 [1994] Weisstein, Eric W. "Jacobi Elliptic Functions". MathWorld.

In mathematics, the Jacobi elliptic functions are a set of basic elliptic functions. They are found in the description of the motion of a pendulum (see also pendulum (mathematics)), as well as in the design of electronic elliptic filters. While trigonometric functions are defined with reference to a circle, the Jacobi elliptic functions are a generalization which refer to other conic sections, the ellipse in particular. The relation to trigonometric functions is contained in the notation, for example, by the matching notation sn {\displaystyle \operatorname {sn} } for sin {\displaystyle \sin } . The Jacobi elliptic functions are used more often in practical problems than the Weierstrass elliptic functions as they do not require notions of complex analysis to be defined and/or understood. They were introduced by Carl Gustav Jakob Jacobi (1829). Carl Friedrich Gauss had already studied special Jacobi elliptic functions in 1797, the lemniscate elliptic functions in particular, but his work was published much later.

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god

Gott (wiktionary)

Possibly from German Gott ("God"). Gott A surname. OGTT From Middle High German got, from Old High German got, from Proto-West Germanic *god, from Proto-Germanic *gudą (“god, deity”). Cognate with German Gott, English God. Gott m (Luserna, Sette Comuni) God Gott dar Hèere ― God the Lord “Gott” in Martalar, Umberto Martello, Bellotto, Alfonso (1974) Dizionario della lingua Cimbra dei Sette Communi vicentini, 1st edition, Roana, Italy: Instituto di Cultura Cimbra A. Dal Pozzo Patuzzi, Umberto, ed., (2013) Luserna / Lusérn: Le nostre parole / Ünsarne börtar / Unsere Wörter [Our Words], Luserna, Italy: Comitato unitario delle isole linguistiche storiche germaniche in Italia / Einheitskomitee der historischen deutschen Sprachinseln in Italien From Middle High German got, from Old High German got, from Proto-West Germanic *god, from Proto-Germanic *gudą, from Proto-Indo-European *ǵʰutós. Compare Dutch god, English god, Danish gud, Gothic 𐌲𐌿𐌸 (guþ). IPA(key): /ɡɔt/ Gott m (strong, genitive Gottes or Gotts, plural Götter, feminine Göttin) god Earlier (16-18th century), the word Gott was also declined as follows: Donnergott Sonnengott See also: Category:de:Gods Gott m (proper noun, strong, genitive Gottes or (rare) Gotts) God The short genitive Gotts is nowadays exceedingly rare in the proper noun. GOtt “Gott” in Duden online “Gott” in Digitales Wörterbuch der deutschen Sprache Kot (Wiesemann spelling system) From Middle High German got, from Old High German got, from Proto-West Germanic *god, from Proto-Germanic *gudą, from Proto-Indo-European *ǵʰutós. IPA(key): /kɔt/ Gott m (plural Getter) God Online Hunsrik Dictionary gód, Gód (widespread variant) Jott (Krefeld) From Proto-West Germanic *god, from Proto-Germanic *gudą, from Proto-Indo-European *ǵʰutós. IPA(key): /ɣɔt/, [ɣot] Homophone: gott Hyphenation: Gott Rhymes: -ɔt Gott m (Eupen) god Gott m (Eupen, rare) God Synonym: Härrgott Gott is rarely used to refer to the Christian god, when referring to the Christian god Härrgott is normally used. Gott is normally instead used to refer to the general concept of a god. From Middle High German got, from Old High German got. Both the vocalism (-o- instead of -a-) and the plural are influenced by German Gott. Also cognate with English god, Dutch god, Icelandic guð, Danish gud. IPA(key): /ɡot/ Rhymes: -ot Gott m God Härgott Gott m (plural Gëtter) god From Middle High German got, from Old High German got, from Proto-West Germanic *god, from Proto-Germanic *gudą (“god, deity”). Cognate with German Gott, English God. Gott m God Patuzzi, Umberto, ed., (2013) Luserna / Lusérn: Le nostre parole / Ünsarne börtar / Unsere Wörter [Our Words], Luserna, Italy: Comitato unitario delle isole linguistiche storiche germaniche in Italia / Einheitskomitee der historischen deutschen Sprachinseln in Italien Borrowed from German Gott. IPA(key): /ɡɔt/ Gott God From Middle High German and Old High German got. Compare German Gott, Dutch god, English god. Gott m (plural Gedder) god From Middle Low German got Gott m (plural Jetta) god Gott m God 2003, De Bibel, Mose I (Genesis) 1:1: gottlooss

83

god

gott (wiktionary)

gott n neuter nominative/accusative singular of góður IPA(key): /kɔht/ Rhymes: -ɔht gott (strong positive degree neuter nominative form of góður (“good”) Genesis 1 (Icelandic translation) Guð sagði: „Verði ljós!“ Og það varð ljós. Guð sá, að ljósið var gott, og Guð greindi ljósið frá myrkrinu. Og Guð kallaði ljósið dag, en myrkrið kallaði hann nótt. Það varð kveld og það varð morgunn, hinn fyrsti dagur. And God said, "Let there be light," and there was light. God saw that the light was good, and He separated the light from the darkness. God called the light "day," and the darkness he called "night." And there was evening, and there was morning—the first day. (strong positive degree neuter accusative form of góður (“good”) eins gott good (widespread variant) gout (Eupen, the variant found in compounds) joot (Krefeld) From Proto-West Germanic *gōd, from Proto-Germanic *gōdaz. IPA(key): /ɣɔt/, [ɣot] Homophone: Gott Hyphenation: gott Rhymes: -ɔt gott (masculine gouwe, feminine go, neuter gott, comparative béëter, superlative béttste) (Eupen) good Gotts gott Eclipsed form of cott. gott strong neuter nominative/accusative singular of góðr IPA(key): /ɡɔt/ Homophone: gått gott indefinite neuter singular of god gott (comparative godare, superlative godast) well, good Det här smakar verkligen gott. ― This tastes really good. gott (archaic) agreed; It's a deal!

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god

god (wiktionary)

From Middle English god, from Old English god, originally neuter, then changed to masculine to reflect the change in religion to Christianity, from Proto-West Germanic *god n, from Proto-Germanic *gudą, from *ǵʰutóm, neuter/inanimate of Proto-Indo-European *ǵʰutós (“invoked (one)”), from Proto-Indo-European *ǵʰewH- (“to call, to invoke”) or *ǵʰew- (“to pour”). Not related to the word good or Persian خدا (xodâ, “god”). Cognates include Russian звать (zvatʹ, “to call”), Sanskrit होत्र (hotra, “calling, oblation, sacrifice”) and Latin fūtilis (“easily pours out, leaky”) (whence English futile). Doublet of futile. enPR: gŏd (Received Pronunciation) IPA(key): /ɡɒd/, (archaic) /ɡɔːd/ (General American, Ireland) IPA(key): /ɡɑd/ (General Australian, New Zealand) IPA(key): /ɡɔd/, /ɡɔːd/ (Canada, Wales) IPA(key): /ɡɒːd/ (Scotland) IPA(key): /ɡɔd/ Homophone: gaud (cot–caught merger) Rhymes: -ɒd god (plural gods) A deity or supreme being; a supernatural, typically immortal, being with superior powers, to which personhood is attributed. Synonyms: see Thesaurus:god An idol. A representation of a deity, especially a statue or statuette. (figurative) Something or someone particularly revered, worshipped, idealized, admired and/or followed. (figurative) A person in a very high position of authority, importance or influence; a powerful ruler or tyrant. (figurative, informal) A person who is exceptionally skilled in a particular activity. (figurative, informal) An exceedingly handsome man. (Internet, roleplaying games) The person who owns and runs a multi-user dungeon. The word god is often applied both to males and to females. The word was originally neuter in Proto-Germanic; monotheistic – notably Judeo-Christian – usage completely shifted the gender to masculine, necessitating the development of a feminine form, goddess. (In Old English the feminine gyden, as well as a more explicitly marked masculine goda, existed.) gawd, Gawd, God Belizean Creole: gaad Sranan Tongo: gado god (often derogatory, also philosophy) Alternative letter-case form of God god (third-person singular simple present gods, present participle godding, simple past and past participle godded) (transitive) To idolize. a. 1866, Edward Bulwer Lytton, "Death and Sisyphus". To men the first necessity is gods; / And if the gods were not, / " Man would invent them, tho' they godded stones. (transitive) To deify. Webster's Seventh New Collegiate Dictionary, Springfield, Massachusetts, G.&C. Merriam Co., 1967 Bosworth, Toller, "An Anglo Saxon Dictionary": http://bosworth.ff.cuni.cz/017298 god on Wikipedia.Wikipedia god (word) on Wikipedia.Wikipedia Dog, OGD, DOG, 'dog, ODG, dog From Old Danish gōþær, gothær, from Old Norse góðr (“good”), from Proto-Germanic *gōdaz. Cognate with English good and German gut. IPA(key): [ˈɡ̊oˀð], [ˈɡ̊oðˀ], [ˈɡ̊oˀ] Rhymes: -oð god (neuter godt, plural and definite singular attributive gode, comparative bedre, superlative (predicative) bedst, superlative (attributive) bedste) good “god” in Den Danske Ordbog From Middle Dutch god, from Old Dutch got, from Proto-West Germanic *god, from Proto-Germanic *gudą, from the Proto-Indo-European *ǵʰutós (“invoked (one)”). Compare English and West Frisian god, German Gott, Danish gud. IPA(key): /ɣɔt/ Rhymes: -ɔt (Belgium) IPA(key): [ʝɔt] (Netherlands) IPA(key): [xɔt] god m (plural goden, diminutive godje n, feminine godin) god, deity See also the derived terms at God. Negerhollands: god, got, godt gōd Romanization of 𐌲𐍉𐌳 good, goot, got (in other dialects) gaud (comparative bäter, beter) (in other dialects) gut (comparative bȩter) (in other dialects) gud (comparative biäter), gutt (inflected gudd-) From Middle Low German gôt, from Old Saxon gōd, from Proto-Germanic *gōdaz. IPA(key): /ɡoʊt/, /ɣɔʊt/, /ɣoʊt/ god (in some dialects) good (alternative spelling of goot) The comparative is bäter and the superlative is best. god Superseded spelling of gód. god m Alternative spelling of got From Old English god, from Proto-West Germanic *god, from Proto-Germanic *gudą, from Proto-Indo-European *ǵʰutós. God, godd, godde IPA(key): /ɡɔd/ god (plural goddes, genitive goddes) A god or deity; a divine individual. A person worshipped as a divinity. English: god Scots: god Yola: gud, Gud, God god (genitive goddes, uncountable) God (the deity of Abrahamic religions, especially the Christian God, considered to be Jesus Christ) a. 1450, The Creation and the Fall of Lucifer in The York Plays, as recorded c. 1463–1477 in British Museum MS. Additional 35290: godfader godmoder godsone English: God, od (archaic, regional, euphemistic); god (as proper noun, often derogatory or in philosophy)→ Pohnpeian: Koht Scots: God Yola: Gud “god”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC. “god, god, n.(1).”, in MED Online, Ann Arbor, Mich.: University of Michigan, 2007, retrieved 2019-02-23. From Old English gōd (“good”). god Alternative form of good god Alternative spelling of gôt. god Alternative spelling of got. Alternative spelling of gôt. From Proto-Athabaskan *-ɢᴜ̓t’. Cognates: Apachean: Western Apache -god, Chiricahua -go’ Others: Hupa -ɢot’, Mattole -goʔł, Galice -gʷay’, Chilcotin -gʷə́d, Slavey, Dogrib -gò, Chipewyan -gór, Sekani -gʷə̀de’, Beaver -gʷəd, Lower Tanana -gᴜd, Hän -gòd, Ahtna -ɢo’d, Dena'ina -ɢət’, Eyak -ɢuʰd IPA(key): [kòt], [kɣʷòt] -god (inalienable) knee agod (“someone’s knee”) hagod (“one’s knee”) bigod (“his/her/their knee”) shigod (“my knee”) From Old Norse góðr, from Proto-Germanic *gōdaz, from Proto-Indo-European *gʰedʰ- (“to join, to unite”). IPA(key): /ɡuː/, [ɡɯᵝː] god (neuter singular godt, definite singular and plural gode, comparative bedre, indefinite superlative best, definite superlative beste) good “god” in The Bokmål Dictionary. From Old Norse góðr, from Proto-Germanic *gōdaz, from Proto-Indo-European *gʰedʰ- (“to join, to unite”). Akin to English good. IPA(key): /ɡuː/ god (masculine and feminine god, neuter godt, definite singular and plural gode, comparative betre, indefinite superlative best, definite superlative beste) good Male given names: From Old Norse goð. IPA(key): /ɡoː/ god ? god (only used in given names) Synonym: gud Male given names: Female given names: “god” in The Nynorsk Dictionary. From Proto-West Germanic *gōd, from Proto-Germanic *gōdaz. IPA(key): /ɡoːd/ gōd (comparative betera, superlative betest, adverb wel) good gōdnes Middle English: good, god, gode, goed, gudeEnglish: goodSolombala English: гудъ (gud), гутъ (gut)Scots: guidYola: gooude, gude, gayde gōd n good (something good or good things collectively) late 10th century, Ælfric, "Ash-Wednesday" goods, possessions c. 992, Ælfric, "The First Sundayin September, when Job is read" From Proto-West Germanic *god, from Proto-Germanic *gudą. Originally neuter, then changed to masculine to reflect the change in religion to Christianity. IPA(key): /ɡod/ god n or m a god late 10th century, Ælfric, "Passion of St. Julian and his wife Basilissa" late 10th century, Ælfric, "Saint George, Martyr" late 10th century, Ælfric, "The Seven Sleepers" neuter masculine ōs godcund (“divine, godlike”) gyden (“goddess”) god m Alternative letter-case form of God. Middle English: god, God, godd, goddeEnglish: godScots: godYola: gud, Gud, God From Proto-West Germanic *gōd. (13th CE) IPA(key): [ɡoːd] Hyphenation: god gōd good North Frisian: Föhr-Amrum: gud Sylt: gur Saterland Frisian: goud West Frisian: goed From Proto-West Germanic *god. (13th CE) IPA(key): [ɡod] Hyphenation: god god m god (Christianity) God North Frisian: Föhr-Amrum: God Saterland Frisian: God West Frisian: god, God Bremmer, Rolf H. (2009) An Introduction to Old Frisian: History, Grammar, Reader, Glossary, Amsterdam: John Benjamins Publishing Company, →ISBN, page 197 From Proto-West Germanic *gōd, from Proto-Germanic *gōdaz, from Proto-Indo-European *gʰedʰ- (“to join, to unite”). Compare Old English gōd, Old Frisian gōd, Old High German guot, Old Dutch guot, Old Norse góðr. IPA(key): /ɣoːd/ IPA(key): /ɡoːd/ gōd (comparative betiro, superlative betst) good Heliand, verse 363 Middle Low German: gôt German Low German: good Low German: goot From Proto-West Germanic *gōd, from Proto-Germanic *gōdaz. IPA(key): /ɣoːd/ IPA(key): /ɡoːd/ gōd n goodness, benefit Heliand, verse 1456 Middle Low German: gôt German Low German: Good Low German: Goot From Proto-West Germanic *god, from Proto-Germanic *gudą, from the Proto-Indo-European *ǵʰutós (“invoked (one)”). Compare Old English god, Old Frisian god, Old High German got, Old Norse guð. IPA(key): /ɣɔd/ IPA(key): /ɡoːd/ god n god Heliand, verse 326 Middle Low German: got From Proto-West Germanic *god, from Proto-Germanic *gudą. IPA(key): /ɣɔd/ IPA(key): /ɡoːd/ god m God, the Christian god Heliand, verse 11 Middle Low German: got guaud (Rumantsch Grischun) uaul, gòld (Sutsilvan) gôt (Surmiran) Of probable Germanic origin (compare German Wald, Dutch woud, English wold). god m (plural gods) (Puter, Vallader) forest Inherited from Proto-Slavic *godъ, from Proto-Balto-Slavic *gadás, from Proto-Indo-European *gʰedʰ-. Cognate with Slovene god, Old Church Slavonic годъ (godŭ), Russian год (god). IPA(key): /ɡôːd/ gȏd m (Cyrillic spelling го̑д) name day anniversary, holiday ring (on a tree) god (Cyrillic spelling год) generalization particle (t)ko god ― whoever što god ― whatever gdje god ― wherever koji god ― whichever Uzmi koji god hoćeš! ― Take whichever you want! kad god ― whenever čiji god ― whoever's kako god ― in whichever way kakav god ― of whatever kind koliki god ― of whichever size koliko god ― no matter how much/many From Proto-Slavic *godъ, from Proto-Balto-Slavic *gadás, from Proto-Indo-European *gʰedʰ-. Cognate with Serbo-Croatian god, Old Church Slavonic годъ (godŭ). IPA(key): /ɡóːt/ gọ̑d m inan name day Synonyms: godovni dan, godovno, imendan name day celebration Synonym: godovanje (obsolete) anniversary[→SSKJ] Synonym: obletnica “god”, in Slovarji Inštituta za slovenski jezik Frana Ramovša ZRC SAZU, portal Fran “god”, in Termania, Amebis See also the general references Borrowed from English god. Compare with god tier. IPA(key): /ˈɡod/ [ˈɡoð̞] Rhymes: -od Syllabification: god god m or f (masculine and feminine plural godes) (Internet slang) fire; cool, amazing; excellent Synonym: genial From Old Swedish gōþer, from Old Norse góðr, from Proto-Germanic *gōdaz, from Proto-Indo-European *gʰedʰ- (“to join, to unite”). IPA(key): /ɡuːd/, (colloquial) /ɡuː/ god (comparative godare or bättre, superlative godast or bäst) good, morally commendable tasty, good (tasting good) Synonyms: välsmakande, (colloquial) go good (having pleasing qualities) good, proficient quite large in extent or degree, good, goodly Synonym: (often) bra good (of friends and the like) In cases where god and bra are idiomatically interchangeable, god often sounds a bit old-fashioned. "God mat" only refers to taste (and is idiomatic when describing food as tasty). "Good food" in a more general sense (well-made, nutritious, tasty, etc. – context-dependent) is "bra mat." (antonym(s) of “not evil”): elak, ond (antonym(s) of “tasty”): äcklig, illasmakande (antonym(s) of “not bad”): dålig go god in Svensk ordbok (SO) god in Svenska Akademiens ordlista (SAOL) god in Svenska Akademiens ordbok (SAOB) dog From Old Frisian god, from Proto-West Germanic *god, from Proto-Germanic *gudą, from Proto-Indo-European *ǵʰutós. god c (plural goaden, diminutive godsje) god, deity “God”, in Wurdboek fan de Fryske taal (in Dutch), 2011

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god

God (wikipedia)

In monotheistic belief systems, God is usually viewed as the supreme being, creator, and principal object of faith. In polytheistic belief systems, a god is "a spirit or being believed to have created, or for controlling some part of the universe or life, for which such a deity is often worshipped". Belief in the existence of at least one god is called theism. Conceptions of God vary considerably. Many notable theologians and philosophers have developed arguments for and against the existence of God. Atheism rejects the belief in any deity. Agnosticism is the belief that the existence of God is unknown or unknowable. Some theists view knowledge concerning God as derived from faith. God is often conceived as the greatest entity in existence. God is often believed to be the cause of all things and so is seen as the creator, sustainer, and ruler of the universe. God is often thought of as incorporeal and independent of the material creation, while pantheism holds that God is the universe itself. God is sometimes seen as omnibenevolent, while deism holds that God is not involved with humanity apart from creation. Some traditions attach spiritual significance to maintaining some form of relationship with God, often involving acts such as worship and prayer, and see God as the source of all moral obligation. God is sometimes described without reference to gender, while others use terminology that is gender-specific. God is referred to by different names depending on the language and cultural tradition, sometimes with different titles of God used in reference to God's various attributes. == Etymology and usage == The earliest written form of the Germanic word God comes from the 6th-century Christian Codex Argenteus. The English word itself is derived from the Proto-Germanic *ǥuđan. The reconstructed Proto-Indo-European form *ǵhu-tó-m was likely based on the root *ǵhau(ə)-, which meant either "to call" or "to invoke". The Germanic words for God were originally neuter, but during the process of the Christianization of the Germanic peoples from their indigenous Germanic paganism, the words became a masculine syntactic form. In the English language, capitalization is used when the word is used as a proper noun, as well as for other names by which a god is known. Consequently, the capitalized form of god is not used for multiple gods or when used to refer to the generic idea of a deity. The English word God and its counterparts in other languages are normally used for any and all conceptions and, in spite of significant differences between religions, the term remains an English translation common to all. El means God in Hebrew, but in Judaism and in Christianity, God is also given a personal name, the tetragrammaton YHWH, in origin possibly the name of an Edomite or Midianite deity, Yahweh. In many English translations of the Bible, when the word LORD is in all capitals, it signifies that the word represents the tetragrammaton. Jah or Yah is an abbreviation of Jahweh/Yahweh, and often sees usage by Jews and Christians in the interjection "Hallelujah", meaning "Praise Jah", which is used to give God glory. In Judaism some of the Hebrew titles of God are considered holy names. Allāh (Arabic: الله) is the Arabic term with no plural used by Muslims and Arabic-speaking Christians and Jews meaning "The God", while ʾilāh (Arabic: إِلَٰه plural `āliha آلِهَة) is the term used for a deity or a god in general. Muslims also use a multitude of other titles for God. In Hinduism, Brahman is often considered a monistic concept of God. God may also be given a proper name in monotheistic currents of Hinduism which emphasize the personal nature of God, with early references to his name as Krishna-Vasudeva in Bhagavata or later Vishnu and Hari. Sang Hyang Widhi Wasa is the term used in Balinese Hinduism. In Chinese religion, Shangdi is conceived as the progenitor (first ancestor) of the universe, intrinsic to it and constantly bringing order to it. Ahura Mazda is the name for God used in Zoroastrianism. "Mazda", or rather the Avestan stem-form Mazdā-, nominative Mazdå, reflects Proto-Iranian *Mazdāh (female). It is generally taken to be the proper name of the spirit, and like its Sanskrit cognate medhā, means "intelligence" or "wisdom". Both the Avestan and Sanskrit words reflect Proto-Indo-Iranian *mazdhā-, from Proto-Indo-European mn̩sdʰeh1, literally meaning "placing (dʰeh1) one's mind (*mn̩-s)", hence "wise". Meanwhile 101 other names are also in use. Waheguru (Punjabi: vāhigurū) is a term most often used in Sikhism to refer to God. It means "Wonderful Teacher" in the Punjabi language. Vāhi (a Middle Persian borrowing) means "wonderful" and guru (Sanskrit: guru) is a term denoting "teacher". Waheguru is also described by some as an experience of ecstasy which is beyond all description. The most common usage of the word "Waheguru" is in the greeting Sikhs use with each other – Waheguru Ji Ka Khalsa, Waheguru Ji Ki Fateh "Wonderful Lord's Khalsa, Victory is to the Wonderful Lord." Baha, the "greatest" name for God in the Baháʼí Faith, is Arabic for "All-Glorious". Other names for God include Aten in ancient Egyptian Atenism where Aten was proclaimed to be the one "true" supreme being and creator of the universe, Chukwu in Igbo, and Hayyi Rabbi in Mandaeism. == General conceptions == === Existence === The existence of God is a subject of debate in theology, philosophy of religion and popular culture. In philosophical terms, the question of the existence of God involves the disciplines of epistemology (the nature and scope of knowledge) and ontology (study of the nature of being or existence) and the theory of value (since some definitions of God include "perfection"). Ontological arguments refer to any argument for the existence of God that is based on a priori reasoning. Notable ontological arguments were formulated by Anselm and René Descartes. Cosmological arguments, such as those described below, use concepts around the origin of the universe to argue for the existence of God. The Teleological argument, also called the ‘’argument from design’’, uses the complexity within the universe as a proof of the existence of God. It is countered that the fine tuning required for a stable universe with life on earth is illusionary, as humans are only able to observe the small part of this universe that succeeded in making such observation possible, called the anthropic principle, and so would not learn of, for example, life on other planets or of universes that did not occur because of different laws of physics. Non-theists have argued that complex processes that have natural explanations yet to be discovered are referred to the supernatural, called god of the gaps. Other theists, such as John Henry Newman who believed theistic evolution was acceptable, have also argued against versions of the teleological argument and held that it is limiting of God to view him having to only intervene specially in some instances rather than having complex processes designed to create order. The Argument from beauty states that this universe happens to contain special beauty in it and that there would be no particular reason for this over aesthetic neutrality other than God. This has been countered by pointing to the existence of ugliness in the universe. This has also been countered by arguing that beauty has no objective reality and so the universe could be seen as ugly or that humans have made what is more beautiful than nature. The Argument from morality argues for the existence of God given the assumption of the objective existence of morals. While prominent non-theistic philosophers such as the atheist J. L. Mackie agreed that the argument is valid, they disagreed with its premises. David Hume argued that there is no basis to believe in objective moral truths while biologist E. O. Wilson theorized that the feelings of morality are a by-product of natural selection in humans and would not exist independent of the mind. Philosopher Michael Lou Martin argued that a subjective account for morality can be acceptable. Similar to the argument from morality is the argument from conscience which argues for the existence of God given the existence of a conscience that informs of right and wrong, even against prevailing moral codes. Philosopher John Locke instead argued that conscience is a social construct and thus could lead to contradicting morals. Atheism is, in a broad sense, the rejection of belief in the existence of deities. Agnosticism is the view that the truth values of certain claims—especially metaphysical and religious claims such as whether God, the divine or the supernatural exist—are unknown and perhaps unknowable. Theism generally holds that God exists objectively and independently of human thought and is sometimes used to refer to any belief in God or gods. Some view the existence of God as an empirical question. Richard Dawkins states that "a universe with a god would be a completely different kind of universe from one without, and it would be a scientific difference." Carl Sagan argued that the doctrine of a Creator of the Universe was difficult to prove or disprove and that the only conceivable scientific discovery that could disprove the existence of a Creator (not necessarily a God) would be the discovery that the universe is infinitely old. Some theologians, such as Alister McGrath, argue that the existence of God is not a question that can be answered using the scientific method. Agnostic Stephen Jay Gould argued that science and religion are not in conflict and proposed an approach dividing the world of philosophy into what he called "non-overlapping magisteria" (NOMA). In this view, questions of the supernatural, such as those relating to the existence and nature of God, are non-empirical and are the proper domain of theology. The methods of science should then be used to answer any empirical question about the natural world, and theology should be used to answer questions about ultimate meaning and moral value. In this view, the perceived lack of any empirical footprint from the magisterium of the supernatural onto natural events makes science the sole player in the natural world. Stephen Hawking and co-author Leonard Mlodinow state in their 2010 book, The Grand Design, that it is reasonable to ask who or what created the universe, but if the answer is God, then the question has merely been deflected to that of who created God. Both authors claim, however, that it is possible to answer these questions purely within the realm of science and without invoking divine beings. === Oneness === A deity, or "god" (with lowercase g), refers to a supernatural being. Monotheism is the belief that there is only one deity, referred to as ‘’God’’ (with uppercase g). Comparing or equating other entities to God is viewed as idolatry in monotheism, and is often strongly condemned. Judaism is one of the oldest monotheistic traditions in the world. Islam's most fundamental concept is tawhid meaning "oneness" or "uniqueness". The first pillar of Islam is an oath that forms the basis of the religion and which non-Muslims wishing to convert must recite, declaring that "I testify that there is no deity except God." In Christianity, the doctrine of the Trinity describes God as one God in Father, Son (Jesus), and Holy Spirit. In past centuries, this fundamental mystery of the Christian faith was also summarized by the Latin formula Sancta Trinitas, Unus Deus (Holy Trinity, Unique God), reported in the Litanias Lauretanas. God in Hinduism is viewed differently by diverse strands of the religion, with most Hindus having faith in a supreme reality (Brahman) who can be manifested in numerous chosen deities. Thus, the religion is sometimes characterized as Polymorphic Monotheism. Henotheism is the belief and worship of a single god at a time while accepting the validity of worshiping other deities. Monolatry is the belief in a single deity worthy of worship while accepting the existence of other deities. === Transcendence === Transcendence is the aspect of God's nature that is completely independent of the material universe and its physical laws. Many supposed characteristics of God are described in human terms. Anselm thought that God did not feel emotions such as anger or love, but appeared to do so through our imperfect understanding. The incongruity of judging "being" against something that might not exist, led many medieval philosophers approach to knowledge of God through negative attributes, called Negative theology. For example, one should not say that God is wise, but can say that God is not ignorant (i.e. in some way God has some properties of knowledge). Christian theologian Alister McGrath writes that one has to understand a "personal god" as an analogy. "To say that God is like a person is to affirm the divine ability and willingness to relate to others. This does not imply that God is human, or located at a specific point in the universe." Pantheism holds that God is the universe and the universe is God and denies that God transcends the Universe. For pantheist philosopher Baruch Spinoza, the whole of the natural universe is made of one substance, God, or its equivalent, Nature. Pantheism is sometimes objected to as not providing any meaningful explanation of God with the German philosopher Schopenhauer stating “Pantheism is only a euphemism for atheism”. Pandeism holds that God was a separate entity but then became the Universe. Panentheism holds that God contains, but is not identical to, the Universe. === Creator === God is often viewed as the cause of all that exists. For Pythagoreans, Monad variously referred to divinity, the first being or an indivisible origin. The philosophy of Plato and Plotinus refers to “The One” which is the first principle of reality that is ‘’beyond’’ being and is both the source of the Universe and the teleological purpose of all things. Aristotle theorized a first uncaused cause for all motion in the universe and viewed it as perfectly beautiful, immaterial, unchanging and indivisible. Aseity is the property of not depending on any cause other than itself for its existence. Avicenna held that there must be a necessarily existent guaranteed to exist by its essence – it cannot ‘’not’’ exist – and that humans identify this as God. Secondary causation refers to God creating the laws of the Universe which then can change themselves within the framework of those laws. In addition to the initial creation, occasionalism refers to the idea that the Universe would not by default continue to exist from one instant to the next and so would need to rely on God as a sustainer. While divine providence refers to any intervention by God, it is usually used to refer to "special providence" where there is an extraordinary intervention by God, such as miracles. === Benevolence === Deism holds that God exists but does not intervene in the world beyond what was necessary to create it, such as answering prayers or producing miracles. Deists sometimes attribute this to God having no interest in or not being aware of humanity. Pandeists would hold that God does not intervene because God is the Universe. Of those theists who hold that God has an interest in humanity, most hold that God is omnipotent, omniscient, and benevolent. This belief raises questions about God's responsibility for evil and suffering in the world. Dystheism, which is related to theodicy, is a form of theism which holds that God is either not wholly good or is fully malevolent as a consequence of the problem of evil. === Omniscience and omnipotence === Omnipotence (all-powerful) is an attribute often ascribed to God. The omnipotence paradox is most often framed with the example "Could God create a stone so heavy that even he could not lift it?" as God could either be unable to create that stone or lift that stone and so could not be omnipotent. This is often countered with variations of the argument that omnipotence, like any other attribute ascribed to God, only applies as far as it is noble enough to befit God and thus God cannot lie, or do what is contradictory as that would entail opposing himself. Omniscience (all-knowing) is an attribute often ascribed to God. This implies that God knows how free agents will choose to act. If God does know this, either their free will might be illusory or foreknowledge does not imply predestination, and if God does not know it, God may not be omniscient. Open Theism limits God's omniscience by contending that, due to the nature of time, God's omniscience does not mean the deity can predict the future and process theology holds that God does not have immutability, so is affected by his creation. === Other concepts === Theologians of theistic personalism (the view held by René Descartes, Isaac Newton, Alvin Plantinga, Richard Swinburne, William Lane Craig, and most modern evangelicals) argue that God is most generally the ground of all being, immanent in and transcendent over the whole world of reality, with immanence and transcendence being the contrapletes of personality. God has also been conceived as being incorporeal (immaterial), a personal being, the source of all moral obligation, and the "greatest conceivable existent". These attributes were all supported to varying degrees by the early Jewish, Christian and Muslim theologian philosophers, including Maimonides, Augustine of Hippo, and Al-Ghazali, respectively. == Non-theistic views == === Religious traditions === Jainism has generally rejected creationism, holding that soul substances (Jīva) are uncreated and that time is beginningless. Some interpretations and traditions of Buddhism can be conceived as being non-theistic. Buddhism has generally rejected the specific monotheistic view of a Creator God. The Buddha criticizes the theory of creationism in the early Buddhist texts. Also, major Indian Buddhist philosophers, such as Nagarjuna, Vasubandhu, Dharmakirti and Buddhaghosa, consistently critiqued Creator God views put forth by Hindu thinkers. However, as a non-theistic religion, Buddhism leaves the existence of a supreme deity ambiguous. There are significant numbers of Buddhists who believe in God, and there are equally large numbers who deny God's existence or are unsure. Taoic religions such as Confucianism and Taoism are silent on the existence of creator gods. However, keeping with the tradition of ancestor veneration in China, adherents worship the spirits of people such as Confucius and Lao Tzu in a similar manner to God. === Anthropology === Some atheists have argued that a single, omniscient God who is imagined to have created the universe and is particularly attentive to the lives of humans has been imagined and embellished over generations. Pascal Boyer argues that while there is a wide array of supernatural concepts found around the world, in general, supernatural beings tend to behave much like people. The construction of gods and spirits like persons is one of the best known traits of religion. He cites examples from Greek mythology, which is, in his opinion, more like a modern soap opera than other religious systems. Bertrand du Castel and Timothy Jurgensen demonstrate through formalization that Boyer's explanatory model matches physics' epistemology in positing not directly observable entities as intermediaries. Anthropologist Stewart Guthrie contends that people project human features onto non-human aspects of the world because it makes those aspects more familiar. Sigmund Freud also suggested that god concepts are projections of one's father. Likewise, Émile Durkheim was one of the earliest to suggest that gods represent an extension of human social life to include supernatural beings. In line with this reasoning, psychologist Matt Rossano contends that when humans began living in larger groups, they may have created gods as a means of enforcing morality. In small groups, morality can be enforced by social forces such as gossip or reputation. However, it is much harder to enforce morality using social forces in much larger groups. Rossano indicates that by including ever-watchful gods and spirits, humans discovered an effective strategy for restraining selfishness and building more cooperative groups. === Neuroscience and psychology === Sam Harris has interpreted some findings in neuroscience to argue that God is an imaginary entity only, with no basis in reality. Johns Hopkins researchers studying the effects of the “spirit molecule” DMT, which is both an endogenous molecule in the human brain and the active molecule in the psychedelic ayahuasca, found that a large majority of respondents said DMT brought them into contact with a "conscious, intelligent, benevolent, and sacred entity," and describe interactions that oozed joy, trust, love, and kindness. More than half of those who had previously self-identified as atheists described some type of belief in a higher power or God after the experience. About a quarter of those afflicted by temporal lobe seizures experience what is described as a religious experience and may become preoccupied by thoughts of God even if they were not previously. Neuroscientist V. S. Ramachandran hypothesizes that seizures in the temporal lobe, which is closely connected to the emotional center of the brain, the limbic system, may lead to those afflicted to view even banal objects with heightened meaning. Psychologists studying feelings of awe found that participants feeling awe after watching scenes of natural wonders become more likely to believe in a supernatural being and to see events as the result of design, even when given randomly generated numbers. == Relationship with humanity == === Worship === Theistic religious traditions often require worship of God and sometimes hold that the purpose of existence is to worship God. To address the issue of an all-powerful being demanding to be worshipped, it is held that God does not need or benefit from worship but that worship is for the benefit of the worshipper. Gandhi expressed the view that God does not need his supplication and that "Prayer is not an asking. It is a longing of the soul. It is a daily admission of one's weakness". Invoking God in prayer plays a significant role among many believers. Depending on the tradition, God can be viewed as a personal God who is only to be invoked directly while other traditions allow praying to intermediaries, such as saints, to intercede on their behalf. Prayer often also includes supplication such as asking forgiveness. God is often believed to be forgiving. For example, a hadith states God would replace a sinless people with one who sinned but still asked repentance. Sacrifice for the sake of God is another act of devotion that includes fasting and almsgiving. Remembrance of God in daily life include mentioning interjections thanking God when feeling gratitude or phrases of adoration, such as repeating chants while performing other activities. === Salvation === Transtheistic religious traditions may believe in the existence of deities but deny any spiritual significance to them. The term has been used to describe certain strands of Buddhism, Jainism and Stoicism. Among religions that do attach spirituality to the relationship with God disagree as how to best worship God and what is God's plan for mankind. There are different approaches to reconciling the contradictory claims of monotheistic religions. One view is taken by exclusivists, who believe they are the chosen people or have exclusive access to absolute truth, generally through revelation or encounter with the Divine, which adherents of other religions do not. Another view is religious pluralism. A pluralist typically believes that his religion is the right one, but does not deny the partial truth of other religions. The view that all theists actually worship the same god, whether they know it or not, is especially emphasized in the Baháʼí Faith, Hinduism and Sikhism. The Baháʼí Faith preaches that divine manifestations include great prophets and teachers of many of the major religious traditions such as Krishna, Buddha, Jesus, Zoroaster, Muhammad, Bahá'ú'lláh and also preaches the unity of all religions and focuses on these multiple epiphanies as necessary for meeting the needs of humanity at different points in history and for different cultures, and as part of a scheme of progressive revelation and education of humanity. An example of a pluralist view in Christianity is supersessionism, i.e., the belief that one's religion is the fulfillment of previous religions. A third approach is relativistic inclusivism, where everybody is seen as equally right; an example being universalism: the doctrine that salvation is eventually available for everyone. A fourth approach is syncretism, mixing different elements from different religions. An example of syncretism is the New Age movement. == Epistemology == === Faith === Fideism is the position that in certain topics, notably theology such as in reformed epistemology, faith is superior than reason in arriving at truths. Some theists argue that there is value to the risk in having faith and that if the arguments for God's existence were as rational as the laws of physics then there would be no risk. Such theists often argue that the heart is attracted to beauty, truth and goodness and so would be best for dictating about God, as illustrated through Blaise Pascal who said, “The heart has its reasons that reason does not know.” A hadith attributes a quote to God as “I am what my slave thinks of me”. Inherent intuition about God is referred to in Islam as fitra, or “innate nature”. In Confucian tradition, Confucius and Mencius promoted that the only justification for right conduct, called the Way, is what is dictated by Heaven, a more or less anthropomorphic higher power, and is implanted in humans and thus there is only one universal foundation for the Way. === Revelation === Revelation refers to some form of message communicated by God. This is usually proposed to occur through the use of prophets or angels. Al-Maturidi argued for the need for revelation because even though humans are intellectually capable of realizing God, human desire can divert the intellect and because certain knowledge cannot be known except when specially given to prophets, such as the specifications of acts of worship. It is argued that there is also that which overlaps between what is revealed and what can be derived. According to Islam, one of the earliest revelations to ever be revealed was “If you feel no shame, then do as you wish.” The term General revelation is used to refer to knowledge revealed about God outside of direct or special revelation such as scriptures. Notably, this includes studying nature, sometimes seen as the Book of Nature. An idiom in Arabic states, "The Qur’an is a Universe that speaks. The Universe is a silent Qur’an". === Reason === On matters of theology, some such as Richard Swinburne, take an evidentialist position, where a belief is only justified if it has a reason behind it, as opposed to holding it as a foundational belief. Traditionalist theology holds that one should not opinionate beyond revelation to understand God's nature and frown upon rationalizations such as speculative theology. Notably, for anthropomorphic descriptions such as the “Hand of God” and attributes of God, they neither nullify such texts nor accept a literal hand but leave any ambiguity to God, called tafwid, without asking how. Physico-theology provides arguments for theological topics based on reason. == Specific characteristics == === Titles === In the Judeo-Christian tradition, "the Bible has been the principal source of the conceptions of God". That the Bible "includes many different images, concepts, and ways of thinking about" God has resulted in perpetual "disagreements about how God is to be conceived and understood". Throughout the Hebrew and Christian Bibles there are titles for God, who revealed his personal name as YHWH (often vocalized as Yahweh or Jehovah). One of them is Elohim. Another one is El Shaddai, translated "God Almighty". A third notable title is El Elyon, which means "The High God". Also noted in the Hebrew and Christian Bibles is the name "I Am that I Am". God is described and referred in the Quran and hadith by certain names or attributes, the most common being Al-Rahman, meaning "Most Compassionate" and Al-Rahim, meaning "Most Merciful". Many of these names are also used in the scriptures of the Baháʼí Faith. Vaishnavism, a tradition in Hinduism, has a list of titles and names of Krishna. === Gender === The gender of God may be viewed as either a literal or an allegorical aspect of a deity who, in classical western philosophy, transcends bodily form. Polytheistic religions commonly attribute to each of the gods a gender, allowing each to interact with any of the others, and perhaps with humans, sexually. In most monotheistic religions, God has no counterpart with which to relate sexually. Thus, in classical western philosophy the gender of this one-and-only deity is most likely to be an analogical statement of how humans and God address, and relate to, each other. Namely, God is seen as begetter of the world and revelation which corresponds to the active (as opposed to the receptive) role in sexual intercourse. Biblical sources usually refer to God using male or paternal words and symbolism, except Genesis 1:26–27, Psalm 123:2–3, and Luke 15:8–10 (female); Hosea 11:3–4, Deuteronomy 32:18, Isaiah 66:13, Isaiah 49:15, Isaiah 42:14, Psalm 131:2 (a mother); Deuteronomy 32:11–12 (a mother eagle); and Matthew 23:37 and Luke 13:34 (a mother hen). In Sikhism, God is "Ajuni" (Without Incarnations), which means that God is not bound to any physical forms. This concludes that the All-pervading Lord is Gender-less. However, the Guru Granth Sahib constantly refers to God as 'He' and 'Father' (with some exceptions), typically because the Guru Granth Sahib was written in north Indian Indo-Aryan languages (mixture of Punjabi and Sant Bhasha, Sanskrit with influences of Persian) which have no neutral gender. From further insights into the Sikh philosophy, it can be deduced that God is, sometimes, referred to as the Husband to the Soul-brides, in order to make a patriarchal society understand what the relationship with God is like. Also, God is considered to be the Father, Mother, and Companion. === Depiction === In Zoroastrianism, during the early Parthian Empire, Ahura Mazda was visually represented for worship. This practice ended during the beginning of the Sasanian Empire. Zoroastrian iconoclasm, which can be traced to the end of the Parthian period and the beginning of the Sassanid, eventually put an end to the use of all images of Ahura Mazda in worship. However, Ahura Mazda continued to be symbolized by a dignified male figure, standing or on horseback, which is found in Sassanian investiture. Deities from Near Eastern cultures are often thought of as anthropomorphic entities who have a human like body which is, however, not equal to a human body. Such bodies were often thought to be radiant or fiery, of superhuman size or extreme beauty. The ancient deity of the Israelites (Yahweh) too was imagined as a transcendent but still anthropomorphic deity. Humans could not see him, because of their impurity in contrast to Yahweh's holiness, Yahweh being described as radiating fire and light which could kill a human if looking at him. Further, more religious or spiritual people tend to have less anthropomorphic depictions of God. In Judaism, the Torah often ascribes human features to God, however, many other passages describe God as formless and otherworldly. Judaism is aniconic, meaning it overly lacks material, physical representations of both the natural and supernatural worlds. Furthermore, the worship of idols is strictly forbidden. The traditional view, elaborated by figures such as Maimonides, reckons that God is wholly incomprehensible and therefore impossible to envision, resulting in a historical tradition of "divine incorporeality". As such, attempting to describe God's "appearance" in practical terms is considered disrespectful to the deity and thus is taboo, and arguably heretical. Gnostic cosmogony often depicts the creator god of the Old Testament as an evil lesser deity or Demiurge, while the higher benevolent god or Monad is thought of as something beyond comprehension having immeasurable light and not in time or among things that exist, but rather is greater than them in a sense. All people are said to have a piece of God or divine spark within them which has fallen from the immaterial world into the corrupt material world and is trapped unless gnosis is attained. Early Christians believed that the words of the Gospel of John 1:18: "No man has seen God at any time" and numerous other statements were meant to apply not only to God, but to all attempts at the depiction of God. However, later depictions of God are found. Some, like the Hand of God, are depiction borrowed from Jewish art. Prior to the 10th century no attempt was made to use a human to symbolize God the Father in Western art. Yet, Western art eventually required some way to illustrate the presence of the Father, so through successive representations a set of artistic styles for symbolizing the Father using a man gradually emerged around the 10th century AD. A rationale for the use of a human is the belief that God created the soul of man in the image of his own (thus allowing humans to transcend the other animals). It appears that when early artists designed to represent God the Father, fear and awe restrained them from a usage of the whole human figure. Typically only a small part would be used as the image, usually the hand, or sometimes the face, but rarely a whole human. In many images, the figure of the Son supplants the Father, so a smaller portion of the person of the Father is depicted. By the 12th century depictions of God the Father had started to appear in French illuminated manuscripts, which as a less public form could often be more adventurous in their iconography, and in stained glass church windows in England. Initially the head or bust was usually shown in some form of frame of clouds in the top of the picture space, where the Hand of God had formerly appeared; the Baptism of Christ on the famous baptismal font in Liège of Rainer of Huy is an example from 1118 (a Hand of God is used in another scene). Gradually the amount of the human symbol shown can increase to a half-length figure, then a full-length, usually enthroned, as in Giotto's fresco of c. 1305 in Padua. In the 14th century the Naples Bible carried a depiction of God the Father in the Burning bush. By the early 15th century, the Très Riches Heures du Duc de Berry had a considerable number of symbols, including an elderly but tall and elegant full-length figure walking in the Garden of Eden, which show a considerable diversity of apparent ages and dress. The "Gates of Paradise" of the Florence Baptistry by Lorenzo Ghiberti, begun in 1425 use a similar tall full-length symbol for the Father. The Rohan Book of Hours of about 1430 also included depictions of God the Father in half-length human form, which were now becoming standard, and the Hand of God becoming rarer. At the same period other works, like the large Genesis altarpiece by the Hamburg painter Meister Bertram, continued to use the old depiction of Christ as Logos in Genesis scenes. In the 15th century there was a brief fashion for depicting all three persons of the Trinity as similar or identical figures with the usual appearance of Christ. In a Trinitarian Pietà, God the Father is often symbolized using a man wearing a papal dress and a papal crown, supporting the dead Christ in his arms. In 1667 the 43rd chapter of the Great Moscow Council specifically included a ban on a number of symbolic depictions of God the Father and the Holy Spirit, which then also resulted in a range of other icons being placed on the forbidden list, mostly affecting Western-style depictions which had been gaining ground in Orthodox icons. The council also declared that the person of the Trinity who was the "Ancient of Days" was Christ, as Logos, not God the Father. However some icons continued to be produced in Russia, as well as Greece, Romania, and other Orthodox countries. In Islam, Muslims believe that God (Allah) is beyond all comprehension, and does not resemble any of his creations in any way. Muslims tend to use the least anthropomorphism among monotheists. They are not iconodules and have religious calligraphy of titles of God instead of pictures. == See also == == References == Footnotes Citations == Bibliography == == External links == Concept of God in Christianity Concept of God in Islam Archived 21 April 2019 at the Wayback Machine God Christian perspective Hindu Concept of God Jewish Literacy Archived 19 December 2010 at the Wayback Machine Who is God Archived 19 December 2010 at the Wayback Machine

In monotheistic belief systems, God is usually viewed as the supreme being, creator, and principal object of faith. In polytheistic belief systems, a god is "a spirit or being believed to have created, or for controlling some part of the universe or life, for which such a deity is often worshipped". Belief in the existence of at least one god is called theism. Conceptions of God vary considerably. Many notable theologians and philosophers have developed arguments for and against the existence of God. Atheism rejects the belief in any deity. Agnosticism is the belief that the existence of God is unknown or unknowable. Some theists view knowledge concerning God as derived from faith. God is often conceived as the greatest entity in existence. God is often believed to be the cause of all things and so is seen as the creator, sustainer, and ruler of the universe. God is often thought of as incorporeal and independent of the material creation, while pantheism holds that God is the universe itself. God is sometimes seen as omnibenevolent, while deism holds that God is not involved with humanity apart from creation. Some traditions attach spiritual significance to maintaining some form of relationship with God, often involving acts such as worship and prayer, and see God as the source of all moral obligation. God is sometimes described without reference to gender, while others use terminology that is gender-specific. God is referred to by different names depending on the language and cultural tradition, sometimes with different titles of God used in reference to God's various attributes.

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God (Australian band) (wikipedia)

God (also stylised as GOD) were an Australian punk rock band formed in 1986 by Sean Greenway on guitar and vocals; Tim Hemensley on bass guitar, drums and vocals; Joel Silbersher on guitar and vocals; and Matthew Whittle on bass guitar, drums and vocals. All four were 15-16 at the time. Their signature song, "My Pal", was released as their debut single in January 1988. Their sole studio album, For Lovers Only, appeared in December 1989 after the group disbanded. Sean Greenway died of a heroin overdose on 21 January 2001, aged 30. Tim Hemensley also died of a heroin overdose, on 21 July 2003, aged 31. Whittle curated their 2× CD compilation album, GOD, in February 2010. == History == God were formed in Melbourne in 1986 as a punk rock quartet by Sean Greenway (p.k.a. Sean Scorpion) on guitar and vocals; Tim Hemensley (p.k.a. Meatcleaver Boy) on bass guitar, drums and vocals; Joel Silbersher (p.k.a. Joel Rock'n'Roll) on guitar and vocals; and Matthew Whittle (p.k.a. Matty Mustang) on bass guitar, drums and vocals. All four were 15-16 at the time. Hemensley had been a member of Royal Flush (with Roman Tucker, later of Rocket Science), Greenway and Whittle were members of Foot and Mouth, and Silbersher was a DJ on community radio, 3RRR. Bruce Milne of Au Go Go Records, who also ran a shop front to sell recordings, met the group's members. He signed them to his label, which issued their debut 7" single, "My Pal", in January 1988. It was written by Silbersher, and received favourable reviews, which sold in the thousands to become, "an enduring Australian underground classic." Australian musicologist, Ian McFarlane, observed, "[they] had an alternative #1 hit on their hands before they were even old enough to get beer riders at their gigs! 'My Pal' was the third biggest selling alternative single for 1988." Andrew Stafford, writer of Pig City: from the Saints to Savage Garden, listed "My Pal" at No. 24 of his "Australian Songbook" in December 2011. He described how, "Silbersher had this song's circular five-note riff in his head for years before one day, in the shower, the lyric came in a rush: 'You’re my only friend / You don't even like me!' Recorded when most of the band were 17 (the video above captures Silbersher with braces still on his teeth)." Stafford felt, "it was such a towering feat that, unfortunately, it overshadowed everything else they ever did." Cover versions were recorded by several artists: Magic Dirt (1997), Violent Soho, Peabody, Bored!, A Death in the Family, the Hollowmen, and Bum (from Canada). Andrew Mueller of The Guardian declared, "[it] started out as an obscure 7" single and ended up revered as a garage band classic, the Aussie equivalent of 'Wild Thing'." God released an eight-track extended play, Rock Is Hell, in December 1988, it appeared in four different cover designs, one by each band member, due to the members' inability to agree on a cover. McFarlane felt, "[it] suffered from slop-bucket production values, but was another statement in God's quest for the ultimate so-bad-its-good trash ethic." Rock Is Hell was variously praised and panned by critics, but still sold respectably. Their full-length studio album, For Lovers Only, appeared in December 1989, via Au Go Go Records which, "boasted stronger production and songs." Although God had disbanded by that time, it was released on vinyl by three European labels. The band's last gig was at the Central Club on 30 July 1989. Au Go Go later released, For Lovers Only, on CD with "My Pal" and most of Rock Is Hell, as bonus tracks. Greenway founded the Freeloaders with members of the Philisteins before releasing an album with The Yes-Men, which included former members of The Meanies, Guttersnipes and The Proton Energy Pills. Hemensley joined fellow punk rockers, Bored!, in late 1989 on bass guitar and vocals, alongside Justin Munday on drums, John Nolan on guitar and Dave Thomas on guitar and vocals. McFarlane felt he "added much to the band's charisma and sense of arrogance." Hemensley and Nolan formed Powder Monkeys in Melbourne in 1991. Silbersher formed Hoss and then Tendrils, he released solo albums, and worked with Tex Perkins. Whittle played with Patterson's Curse, Sauce, Ripe, Offal Pump, Baby 8 and Melwayholics Anonymous. Sean Greenway (born 4 December 1970) died of a heroin overdose on 21 January 2001, aged 30. Tim Hemensley died of a heroin overdose in 2003. "My Pal" appeared on the Underbelly soundtrack for the TV series of the same name. It was used on the Australian TV film, Underground – The Julian Assange Story. God's self-titled double CD reissue was released on Afterburn Records in February 2010. BMA Magazine's correspondent described the group, "[they] sounded like a ten train smash-up in Tin Railroad Town. They were trying to encapsulate stadium rock and their ‘monster riffs’ often sounded like a playgroup had broken into the bottle recycling bin combined with that siren song of crap amps buzzing and wheezing you sometimes hear just before they blow up." == References == Stranded: The Secret History of Australian Independent Music 1977-1991, Clinton Walker, Pan MacMillan, 1996, ISBN 0-7329-0883-3. == External links == Webcuts Essay celebrating "My Pal" Playlist 10 September 2005 for ABC TV Rage with My Pal still being selected Official God Myspace God discography at Discogs

God (also stylised as GOD) were an Australian punk rock band formed in 1986 by Sean Greenway on guitar and vocals; Tim Hemensley on bass guitar, drums and vocals; Joel Silbersher on guitar and vocals; and Matthew Whittle on bass guitar, drums and vocals. All four were 15-16 at the time. Their signature song, "My Pal", was released as their debut single in January 1988. Their sole studio album, For Lovers Only, appeared in December 1989 after the group disbanded. Sean Greenway died of a heroin overdose on 21 January 2001, aged 30. Tim Hemensley also died of a heroin overdose, on 21 July 2003, aged 31. Whittle curated their 2× CD compilation album, GOD, in February 2010.

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God (British band) (wikipedia)

God (stylised in all caps) were a British experimental band formed in London by Kevin Martin. The band's first official release was 'Sounds Like Thunder' in 1988, for a Mark E. Smith-curated 'Disparate Cognescenti' compilation. The band expanded to include nine members and released two studio albums before disbanding in 1996. The group's abrasive combination of ambient, dub, free jazz and noise rock music garnered respect from their peers such as Bill Laswell, Ministry, My Bloody Valentine, J. G. Thirlwell and John Zorn. == History == God originally consisted of Kevin Martin on tenor saxophone and vocals and Nigel Armstrong on guitar. The pairing came together after the pair, along with Andy Rendall (Admass) relocated from Weymouth to London, and Fall frontman Mark E. Smith asked Martin if he wanted to contribute to Smith's 1988 Disparate Cognescenti compilation. In late 1988, Martin met Justin Broadrick, whose project Godflesh he had heard on John Peel's Radio 1 show. Broadrick began working with Martin and served as a producer for God's early releases before joining as a member. == Discography == Studio albums Possession (1992, Virgin) The Anatomy of Addiction (1994, Big Cat) Live albums Loco (1991, Pathological) Consumed (1993, Sentrax) Singles and EPs Breach Birth (1990, Situation Two) Car First (1990, Clawfist) a split 7-inch with Terminal Cheesecake Appeal to Human Greed (1995, Big Cat) == References == == External links == God at AllMusic God discography at Discogs

God (stylised in all caps) were a British experimental band formed in London by Kevin Martin. The band's first official release was 'Sounds Like Thunder' in 1988, for a Mark E. Smith-curated 'Disparate Cognescenti' compilation. The band expanded to include nine members and released two studio albums before disbanding in 1996. The group's abrasive combination of ambient, dub, free jazz and noise rock music garnered respect from their peers such as Bill Laswell, Ministry, My Bloody Valentine, J. G. Thirlwell and John Zorn.

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God (Derzhavin ode) (wikipedia)

God (Russian title: Бог Bog; finished 1784) is a poem by Gavrila Derzhavin. == Background == In the 18th century the deists of various European nations reveled in singing praises to God. Such odes were produced by Voltaire, Klopstock, Haller, Brockes and Young. In Russia, the fashion was set by Lomonosov's "The True God". == Description == Derzhavin commenced writing "God" in 1780, but finished it only in 1784, under the influence of a strong religious emotion. It begins with an appeal to God, then extols the infinite power and wisdom of the Divinity. The individual is the reflex of the Divinity, and hence not insignificant. The relationship to God is recognized and, therefore, immortality beyond the grave is assured. == Translations == Derzhavin's "God" was at once translated into most of the European languages and into Japanese by Admiral Golovnin. There are at least 15 French versions of the poem, while in English available translations include: "To God", in The Bakchesarian Fountain (Philadelphia, 1849) by W. D. Lewis; "Ode to the Deity", by J. K. Stallybrass in The Leisure Hour (London) of May 2, 1870; and "Ode to God", by N. H. Dole in volume X of The Chautauquan. Stanisław Czerski translated the ode into Latin in 1815: "Carmen de Deo". == Notes == == References == This article incorporates text from a publication now in the public domain: Wiener, Leo (1920). "Ode to God, The" . In Rines, George Edwin (ed.). Encyclopedia Americana. == External links == Bilingual text Archived 2007-10-18 at the Wayback Machine at max.mmlc.northwestern.edu

God (Russian title: Бог Bog; finished 1784) is a poem by Gavrila Derzhavin.

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God (John Lennon song) (wikipedia)

"God" is a song by English musician John Lennon, from his first post-Beatles solo album, John Lennon/Plastic Ono Band. The album was released on 11 December 1970 in the United States and the United Kingdom. == Meaning == There are three sections in the song. In the first section, John Lennon describes God as "a concept by which we measure our pain". In the second, Lennon chants a Cartesian list of things he does not believe in, ending by stating that he just believes in himself (individuality) and Yoko (his wife). He rejects magic, the I Ching, the Bible, tarot, Hitler, Jesus, Kennedy, the Buddha, mantra, the Gita, yoga, kings, Elvis, Zimmerman (Bob Dylan), and the Beatles. The final section describes Lennon's change since the break-up of the Beatles. While the Beatles were basically his family throughout the 1960s, he refers to Paul McCartney's 1965 Beatles song "Yesterday", and states that he is no longer the "Dreamweaver" or "The Walrus", but just "John". The final line of the song, "The dream is over", has been seen as declaring the end of the 1960s quest for meaning. "If there is a God", Lennon explained, "we're all it". == Legacy == The Irish rock band U2 wrote and recorded the song "God Part II" as an answer song to Lennon's "God". Included in U2's 1988 album Rattle and Hum, "God Part II" reprises the "don't believe in" motif from Lennon's song and its lyrics explicitly reference Lennon's 1970 song "Instant Karma!" and American biographer Albert Goldman, author of the controversial book The Lives of John Lennon (1988). English musician David Bowie, a friend and one-time musical collaborator with Lennon, wrote and recorded the song "Afraid", which was included in his 2002 album Heathen; one of the song's lyrics, "I believe in Beatles", is a rejoinder to Lennon singing "I don't believe in Beatles" in "God". == Personnel == The musicians who performed on the original recording were as follows: John Lennon – vocals, tack piano Billy Preston – grand piano Ringo Starr – drums Klaus Voormann – bass guitar == See also == Religious views of the Beatles == Notes ==

"God" is a song by English musician John Lennon, from his first post-Beatles solo album, John Lennon/Plastic Ono Band. The album was released on 11 December 1970 in the United States and the United Kingdom.

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God (Kendrick Lamar song) (wikipedia)

"God" (stylized as "GOD.") is a song by American rapper Kendrick Lamar, from his fourth studio album Damn, released on April 14, 2017. The thirteenth and penultimate track on the album (second on the Collector's Edition of Damn), the song was produced by Riera, Sounwave, DJ Dahi, Bëkon, Cardo, Tiffith, with additional production by Yung Exclusive, Mike Hector and Teddy Walton. The song details Lamar's successes, how it feels, and why he works so hard to get to where he is today. The song also finds Lamar declaring his faux-divinity as a rap god. == Background == Before the release of Damn, the album itself was rumored to be centered around God. It was soon confirmed by Lamar himself. Lamar has been a devout Christian since approximately his late teen years or adolescence. == Lyrics == According to Jake Woolf of GQ magazine, Lamar trolls Canadian musician and rapper Drake by imitating his singing voice on the song's chorus. == Live performances == Lamar performed "God" live at the Coachella Valley Music and Arts Festival on April 23, 2017. Lamar has performed "God" at every show as an encore on the Damn tour. == Credits and personnel == Credits adapted from the official Damn digital booklet. Kendrick Lamar – songwriter Ricci Riera – songwriter, producer Mark Spears – songwriter, producer Dacoury Natche – songwriter, producer Daniel Tannenbaum – songwriter Bēkon – producer, additional vocals Ronald LaTour – songwriter, producer Anthony Tiffith – songwriter, producer Mike Hector – additional drums Derek Ali – mixing Tyler Page – mix assistant Cyrus Taghipour – mix assistant == Charts == == Certifications == == References ==

"God" (stylized as "GOD.") is a song by American rapper Kendrick Lamar, from his fourth studio album Damn, released on April 14, 2017. The thirteenth and penultimate track on the album (second on the Collector's Edition of Damn), the song was produced by Riera, Sounwave, DJ Dahi, Bëkon, Cardo, Tiffith, with additional production by Yung Exclusive, Mike Hector and Teddy Walton. The song details Lamar's successes, how it feels, and why he works so hard to get to where he is today. The song also finds Lamar declaring his faux-divinity as a rap god.

91

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God (Louie) (wikipedia)

"God" is the eleventh episode of the first season of the American comedy-drama television series Louie. The episode was written and directed by Louis C.K., who also serves as the lead actor. It was released on FX on August 31, 2010. The series follows Louie, a fictionalized version of C.K., a comedian and newly divorced father raising his two daughters in New York City. In the episode, Louie revisits his past, when he faced questions about Jesus while attending a Catholic school when he was younger. According to Nielsen Media Research, the episode was seen by an estimated 0.760 million household viewers and gained a 0.4 ratings share among adults aged 18–49. The episode received critical acclaim, with critics praising the episode's humor and exploration of its characters and themes. == Plot == At a gas station, Louie (Louis C.K.) goes to the restroom, discovering a glory hole. A customer also arrives and prepares to use the glory hole, until he is called out by Louie. When he asks him how does he know nothing bad will happen, the man replies that he must have faith. In 1977, a young Louie (Sawyer Swanson) attends a Catholic school, where he and friends question the Crucifixion of Jesus, particularly his suffering. To change their minds, a nun (Ann Dowd) hires a doctor, Dr. Haveford (Tom Noonan), to give a detailed description of Jesus' suffering. Louie and his friend get frightened by the details, especially when the doctor asks Louie to replicate hitting Jesus with the nails. Louie is haunted by nightmares, so he returns to the church and releases Jesus from his Cross by removing the nails. After being scolded by the nun, Louie's mother (Amy Landecker) talks with Louie. Seeing his fears, she tells him that he had nothing to do with Jesus, as he does not need to rely on dogma to be a good person. In present day, Louie uses some of his religious background for a performance at the Comedy Cellar. == Production == === Development === The episode was written and directed by series creator and lead actor Louis C.K., marking his eleventh writing and directing credit for the series. == Reception == === Viewers === In its original American broadcast, "God" was seen by an estimated 0.760 million household viewers with a 0.4 in the 18-49 demographics. This means that 0.4 percent of all households with televisions watched the episode. This was a 31% increase in viewership from the previous episode, which was watched by 0.577 million viewers with a 0.3 in the 18-49 demographics. === Critical reviews === "God" received critical acclaim. Nathan Rabin of The A.V. Club gave the episode an "A" grade and wrote, "In the past I've called Louie a show about everything. In tonight's episode C.K. stops wasting his time addressing minor concerns like class, race, sexuality, divorce, dating, childhood, and aging and finally tackles something important: God." Alan Sepinwall of HitFix wrote, "Though there were technically two vignettes in 'God,' the joke about the gas station glory hole was just there to set up the much longer, darker flashback to Louie's childhood and his issues with the Catholic Church. This was one of the darkest, most deliberately non-comic episodes yet, and also one of the most fascinating." Emily St. James of Los Angeles Times wrote, "In the end, though, 'God' is another very funny episode of Louie, and a great way to send the show into its hour-long finale next week. With all of the other subjects the series has tackled so far, it was obvious that it would eventually get to religion, and I like the show's hyper-specific, very Catholic take on the subject. Louie is best when it's expressing its central character's specific point of view, and 'God' was full of moments that did exactly that." Ian McDonald of TV Overmind wrote, "What was refreshing about tonight's Louie is that he didn't have anything particularly positive or negative to say about religion other than pointing out how some commandments have some messed up priorities. The whole episode was about his experience with it, which I then interpreted as a fairly negative experience." == References == == External links == "God" at IMDb

"God" is the eleventh episode of the first season of the American comedy-drama television series Louie. The episode was written and directed by Louis C.K., who also serves as the lead actor. It was released on FX on August 31, 2010. The series follows Louie, a fictionalized version of C.K., a comedian and newly divorced father raising his two daughters in New York City. In the episode, Louie revisits his past, when he faced questions about Jesus while attending a Catholic school when he was younger. According to Nielsen Media Research, the episode was seen by an estimated 0.760 million household viewers and gained a 0.4 ratings share among adults aged 18–49. The episode received critical acclaim, with critics praising the episode's humor and exploration of its characters and themes.

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God (Rebecca St. James album) (wikipedia)

God is the third studio album by then 18-year-old Christian pop and rock artist Rebecca St. James. It was released on 25 June 1996 by ForeFront Records, and peaked at No. 200 on the Billboard 200. The title song was featured on WOW #1s: 31 of the Greatest Christian Music Hits Ever. It was RIAA Certified Gold in 2005. This was the first of many Rebecca St. James albums produced by Tedd Tjornhom. == Commercial performance == The song "God" was a hit in 1996, topping three Christian Rock Charts. The radio singles "You're the Voice", "Abba (Father)" and "Go & Sin No More" also did well, while the single "Me Without You" failed to gain major airplay. Though never released as singles "Psalm 139", "Speak to Me" and "You Then Me" have all become fan favorites. == Track listing == == Personnel == Rebecca St. James – lead and backing vocals, arrangements Tedd T – arrangements, acoustic piano, Fender Rhodes, harmonica, programming, bass, percussion Carl Marsh – accordion, Mellotron, string arrangements David Cleveland – acoustic guitars Vince Emmett – electric guitar, steel guitar Brent Milligan – electric guitar, bass, percussion Otto Price – electric guitar, bass Chuck Zwicky – additional guitars (2) Dan Needham – drums, percussion Hunter Lee – Uilleann pipes, Irish flute, didjeridu Josh Smallbone – guest MC (8) Tina Keil – additional backing vocals (10) Paul Q-Pek – additional backing vocals (10) Lori Wilshire – additional backing vocals (10) Micah Wilshire – additional backing vocals (10) == Production == Tedd T – producer, recording Dan R. Brock – executive producer Eddie DeGarmo – executive producer Julian Kindred – recording, mix assistant (2-10) Tom Laune – recording Paul Salvo – recording Peter Briggs – recording assistant Greg Parker – recording assistant Shane D. Wilson – recording assistant John Hampton – mixing (1) Skidd Mills – mixing (1) Chuck Zwicky – mixing (2-10) Chuck Linder – mix assistant (2-10) Daryl Smith – mix assistant (2-10) Ken Love – mastering Tom Davis – art direction, design Jeff Frazier – photography Geenie Freeman – make-up David Smallbone – management Studios Recorded at 9070 Studios (Brentwood, Tennessee). Track 1 mixed at Ardent Studios (Memphis, Tennessee). Tracks 2-10 mixed at 9070 Studios; Recording Arts Studio (Nashville, Tennessee); Gambit Studio (Gallatin, Tennessee); Secret Sound (Franklin, Tennessee). Mastered at MasterMix (Nashville, Tennessee). == Charts == Album - Billboard (North America) Singles - CCM Magazine (North America) == References ==

God is the third studio album by then 18-year-old Christian pop and rock artist Rebecca St. James. It was released on 25 June 1996 by ForeFront Records, and peaked at No. 200 on the Billboard 200. The title song was featured on WOW #1s: 31 of the Greatest Christian Music Hits Ever. It was RIAA Certified Gold in 2005. This was the first of many Rebecca St. James albums produced by Tedd Tjornhom.

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God (Rebecca St. James song) (wikipedia)

"God" is a 1996 single by Christian pop-rock singer Rebecca St. James. The song is from the album of the same name. == Track listing == "God" – 4:08 "God" (Remix) – 4:21 "Sweet, Sweet Song of Salvation" – 3:53 "Side By Side Remix" – 6:53 "He Is Exalted" – 3:31 The song "He Is Exalted" came from the album Prayers and Worship and Michelle Ray sang it. St.James did a spoken word performance in the beginning. KJ-52 in 2005 did a remix of this song with St. James singing the chorus. The song is on the album Behind the Musik (A Boy Named Jonah). == Music video == A music video for the song was released containing footage of the artist singing intermingled with clips of the sun and other nature scenes. == References ==

"God" is a 1996 single by Christian pop-rock singer Rebecca St. James. The song is from the album of the same name.

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God (Rip Rig + Panic album) (wikipedia)

God is the debut studio album of post-punk band Rip Rig + Panic, released on 3 September 1981 by Virgin Records. It took the unusual form of two 12" 45 rpm discs, a format which would be repeated with the group's second album, I Am Cold. In 2013, the album was reissued by Cherry Red Records on CD with an additional tracks taken from singles. == Track listing == All tracks composed by Rip Rig + Panic; except where indicated == Accolades == == Personnel == Adapted from the God liner notes. == Release history == == References == == External links == God at Discogs (list of releases)

God is the debut studio album of post-punk band Rip Rig + Panic, released on 3 September 1981 by Virgin Records. It took the unusual form of two 12" 45 rpm discs, a format which would be repeated with the group's second album, I Am Cold. In 2013, the album was reissued by Cherry Red Records on CD with an additional tracks taken from singles.

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God (Tori Amos song) (wikipedia)

"God" is a song by American singer-songwriter and musician Tori Amos, released as a single from her second studio album, Under the Pink (1994). It was issued as the album's lead single in the United States on February 3, 1994, as the second single in Australia on May 2, and as the fourth single in the United Kingdom on October 3. The song reached number 44 on the UK Singles Chart as well as number one on the US Billboard Modern Rock Tracks chart. It became Amos's first single to chart on the Billboard Hot 100, peaking at number 72. == Releases == The B-sides to the American release include Tori Amos' reworking of "Home on the Range" with new lyrics as well as a two-song instrumental piano suite. An American cassette single includes the B-side "Sister Janet". A different single was released in Europe on CD, 12 in (300 mm) vinyl, 7 in (180 mm) vinyl, and cassette. The 7 in (180 mm) single is a glossy, dual-sided picture disc. The various formats include ambient and jungle house remixes of the track by CJ Bolland, Carl Craig, and the Joy. == Reception == Stereogum and The Guardian both named "God" as Amos's third-greatest song. == Music video == The accompanying music video for "God" directed by Melodie McDaniel features Amos in a variety of religiously-themed situations, such as a scene visually comparing a tefillin used by a rabbi with a basketball player using a belt while injecting drugs. The video is often remembered for scenes of Amos singing in front of a lit candle, dancing with a plethora of brown rats (possibly at the Rat temple); this was commented on in an episode of the television show Beavis and Butt-head, and parodying a snake cult. == Track listings == == Credits and personnel == Credits are adapted from the Under the Pink album booklet. Studios Recorded at The Fishhouse (New Mexico, US) Mixed at Olympic Studios (London, England) Mastered at Gateway Mastering (Portland, Maine, US) Personnel == Charts == == Release history == == References == == External links == "God" official video on YouTube

"God" is a song by American singer-songwriter and musician Tori Amos, released as a single from her second studio album, Under the Pink (1994). It was issued as the album's lead single in the United States on February 3, 1994, as the second single in Australia on May 2, and as the fourth single in the United Kingdom on October 3. The song reached number 44 on the UK Singles Chart as well as number one on the US Billboard Modern Rock Tracks chart. It became Amos's first single to chart on the Billboard Hot 100, peaking at number 72.

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God (disambiguation) (wikipedia)

God is a monotheist conception of a supreme being and principal object of faith. Gods or deities are natural or supernatural beings considered divine or sacred, depending on tradition. God may also refer to: God (word), the English word == Places == Göd, a town in Pest County, Hungary God, a WWI British troop nickname for Godewaersvelde, France Godalming railway station, England, station code GOD == People == === Given name === God Nisanov (born 1972), Russian property developer God Shammgod (born 1976), American basketball player and coach === Nickname === HITEK5000, formerly known as "God", producer of Die Antwoord Eric Clapton (born 1945), English musician Gus O'Donnell (born 1952), former UK civil service head Gary Ablett Sr. (born 1961), Australian-rules football player Robbie Fowler (born 1975), English former footballer == Arts, entertainment, and media == === Fictional entities === God (The Hitchhiker's Guide to the Galaxy), a sci-fi comedy character God (The Simpsons), a character in the animated television sitcom God, a fictional music album by The Beatles in Stephen Baxter's "The Twelfth Album" Government Of Darkness, a fictional criminal empire in the Japanese Kamen Rider X TV series === Gaming === God (MUD), a senior administrator in a multi-user dungeon Gates of Discord, an EverQuest game expansion === Music === ==== Groups and labels ==== God (Australian band), an Australian indie rock band God (British band), a London-based industrial band g.o.d (South Korean band), a South Korean boy band ==== Albums ==== God (Rebecca St. James album), 1996 God (Rip Rig + Panic album), 1981 G.O.D. (Gold, Oil & Diamonds), a 2009 mixtape by AZ God LP, a 2016 album by Inhuman G.O.D., a 2020 extended play by Virgen María ==== Songs ==== "God" (John Lennon song), on the album John Lennon/Plastic Ono Band "God" (Kendrick Lamar song), 2017 "God" (Tori Amos song), 1994 "God" (Rebecca St. James song), 1996 "God", by Outkast, on the 2003 album Speakerboxxx/The Love Below "God", by Prince, B-side of single "Purple Rain" "God", by Relient K, on the 2016 album Air for Free "God", by Smashing Pumpkins, B-side of single "Zero" "God", by Weird Owl, on the 2015 album Interstellar Skeletal === Other arts, entertainment, and media === God (play), a 1975 one-act play by Woody Allen God (sculpture), a 1917 readymade artwork by Elsa von Freytag-Loringhoven GOD TV, an international Christian broadcaster G.O.D (web series), a 2019 Indian Telugu-language web series. == Religion == God in Abrahamic religions God in the Baháʼí Faith God in Buddhism God in Christianity God in Hinduism God in Islam God in Jainism God in Judaism God in Mormonism == Brands and enterprises == Gathering of Developers, a defunct video game publisher Goods of Desire, Hong Kong company == Other uses == Guerrillas of Destiny, professional wrestling tag team (sometimes shortened to G.O.D.) Horned God, a figure in Wicca and other forms of Modern Paganism == See also == All pages with titles beginning with God Dear God (disambiguation) God and Satan (disambiguation) God mode (disambiguation) Goddess (disambiguation) Gods (disambiguation) Good (disambiguation) My God (disambiguation) Oh My God (disambiguation)

God is a monotheist conception of a supreme being and principal object of faith. Gods or deities are natural or supernatural beings considered divine or sacred, depending on tradition. God may also refer to: God (word), the English word

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God (play) (wikipedia)

God, subtitled A Comedy in One Act, is a play by Woody Allen. It was first published in 1975, along with Death, and Allen's short stories in Woody Allen's book Without Feathers. The comedy is modelled after Bertolt Brecht's epic theatre, in that the characters frequently point out the artificiality of the play and switch roles. Actors also play various audience members, and Woody Allen himself appears at one point as a voice on a phone. == Plot == The setting is an ancient Greek amphitheatre, circa 500BC. Diabetes, an actor, and Hepatitis, a writer, sit on stage lamenting about how Hepatitis' new play lacks a good ending. They begin to frequently break the fourth wall, interacting with the audience and making note about how they are fictional characters in a play. Hepatitis asks if anyone has a major in philosophy, resulting in an audience member named Doris Levine joining the action on stage, while Diabetes calls the play's author Woody Allen for advice on how to proceed. Another playwright, Trichinosis, joins the stage, saying that he has a machine that will help give the play a satisfying ending. The machine creates thunder and lightning effects, and allows an actor to descend from the roof in a harness in order to play God descending from the heavens to intervene at the conclusion in Hepatitis' play. Doris notes that this is a deus ex machina, while Hepatitis begins questioning God's existence. Eventually, another playwright named Lorenzo Miller enters and says that he author of a greater play, and that the real audience is fictional. Blanche DuBois enters, saying that she is tired of the brutality of Tennessee Williams' play. Hepatitis finally accepts Trichinosis' machine, and his play begins. The play-within-a-play involves Diabetes playing a slave who is forced to courier a message to the king. He is nervous after being told that if the message is bad news, the king will execute him; he opens the message, but is not reassured when it reads only the word "Yes". He eventually reaches the king's castle and realises that "Yes" is an affirmative, and thus fundamentally good. However, the king reveals that the question that the message provides the answer for is: "Is there a God?", which enrages the king as it means that he will go to Hell for his sins. Just as the king is to execute Diabetes' character, Trichinosis' machine malfunctions and strangles the actor playing God. Hepatitis hurriedly tells Diabetes to ad-lib the ending, but several other fictional characters appear and several members of the audience begin to run amok at the breakdown of reality. Eventually, all the other actors leave and Diabetes and Hepatitis sit on stage alone together, repeating their lines from the beginning about the need for a good ending, suggesting that the entire play exists in an infinite loop. == References == == External links == Play Synopsis Play Script FortuneCity God 2 March 1986 BBC Radio 3

God, subtitled A Comedy in One Act, is a play by Woody Allen. It was first published in 1975, along with Death, and Allen's short stories in Woody Allen's book Without Feathers. The comedy is modelled after Bertolt Brecht's epic theatre, in that the characters frequently point out the artificiality of the play and switch roles. Actors also play various audience members, and Woody Allen himself appears at one point as a voice on a phone.

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God (sculpture) (wikipedia)

God is a circa 1917 sculpture by New York Dadaists Morton Livingston Schamberg and Elsa von Freytag-Loringhoven. It is an example of readymade art, a term coined by Marcel Duchamp in 1915 to describe his found objects. God is a 10½ inch high cast iron plumbing trap turned upside down and mounted on a wooden mitre box. The work is now in the Arensberg Collection in the Philadelphia Museum of Art. It is now compared to Marcel Duchamp's famous Fountain sculpture which consists of an upended urinal. Both works were created in the same year and there is some uncertainty about who first had the idea of turning plumbing into art. Duchamp and the Baroness were friends and she later made a found-object portrait of Duchamp. God was originally solely attributed to artist Morton Livingston Schamberg. The Philadelphia Museum of Art now recognizes the Baroness as a co-artist of this piece. However, according to the scholar Francis Naumann, it is reasonable to conclude, based on the works known to have been made by her, that the Baroness most likely came up with the concept of combining the two elements of the sculpture and provided the title, while Schamberg assembled and photographed the piece. == References ==

God is a circa 1917 sculpture by New York Dadaists Morton Livingston Schamberg and Elsa von Freytag-Loringhoven. It is an example of readymade art, a term coined by Marcel Duchamp in 1915 to describe his found objects. God is a 10½ inch high cast iron plumbing trap turned upside down and mounted on a wooden mitre box. The work is now in the Arensberg Collection in the Philadelphia Museum of Art. It is now compared to Marcel Duchamp's famous Fountain sculpture which consists of an upended urinal. Both works were created in the same year and there is some uncertainty about who first had the idea of turning plumbing into art. Duchamp and the Baroness were friends and she later made a found-object portrait of Duchamp. God was originally solely attributed to artist Morton Livingston Schamberg. The Philadelphia Museum of Art now recognizes the Baroness as a co-artist of this piece. However, according to the scholar Francis Naumann, it is reasonable to conclude, based on the works known to have been made by her, that the Baroness most likely came up with the concept of combining the two elements of the sculpture and provided the title, while Schamberg assembled and photographed the piece.

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God (word) (wikipedia)

The English word god comes from the Old English god, which itself is derived from the Proto-Germanic *gudą. Its cognates in other Germanic languages include guþ, gudis (both Gothic), guð (Old Norse), god (Old Saxon, Old Frisian, and Old Dutch), and got (Old High German). == Etymology == The Proto-Germanic meaning of *gudą and its etymology is uncertain. It is generally agreed that it derives from a Proto-Indo-European neuter passive perfect participle *ǵʰu-tó-m.: 193–194 This form within (late) Proto-Indo-European itself was possibly ambiguous, and thought to derive from a root *ǵʰew- "to pour, libate" (the idea survives in the Dutch word giet, meaning "pour") (Sanskrit huta, see hotṛ), or from a root *ǵʰaw- (*ǵʰewh2-) "to call, to invoke" (Sanskrit hūta). Sanskrit hutá = "having been sacrificed", from the verb root hu = "sacrifice", but a slight shift in translation gives the meaning "one to whom sacrifices are made." Thus it can be related to the ancient Indian name Gautam and its Sanskrit roots. Depending on which possibility is preferred, the pre-Christian meaning of the Germanic term may either have been (in the "pouring" case) "libation" or "that which is libated upon, idol" — or, as Watkins opines in the light of Greek χυτη γαια "poured earth" meaning "tumulus", "the Germanic form may have referred in the first instance to the spirit immanent in a burial mound" — or (in the "invoke" case) "invocation, prayer" (compare the meanings of Sanskrit brahman) or "that which is invoked". The term "Godan" was the name used for Wodan amongst the pre-Christian Lombards. === Influence of Christianity === God entered English when the language still had a system of grammatical gender. The word and its cognates were initially neutral but underwent transition when their speakers converted to Christianity, "as a means of distinguishing the personal God of the Christians from the impersonal divine powers acknowledged by pagans.": 15 However, traces of the neuter endured. While these words became syntactically masculine, so that determiners and adjectives connected to them took masculine endings, they sometimes remained morphologically neuter, which could be seen in their inflections: In the phrase, guþ meins, "my God," from the Gothic Bible, for example, guþ inflects as if it were still a neuter because it lacks a final -s, but the possessive adjective meins takes the final -s that it would with other masculine nouns.: 15 God and its cognates likely had a general, predominantly plural or collective sense prior to conversion to Christianity. After conversion, the word was commonly used in the singular to refer to the Christian deity, and also took on characteristics of a name.: 15–16 == Translations == The word god was used to represent Greek theos and Latin deus in Bible translations, first in the Gothic translation of the New Testament by Ulfilas. For the etymology of deus, see *dyēus. Greek "θεός " (theos) means god in English. It is often connected with Greek "θέω" (theō), "run", and "θεωρέω" (theoreō), "to look at, to see, to observe", Latin feriae "holidays", fanum "temple", and also Armenian di-k` "gods". Alternative suggestions (e.g. by De Saussure) connect *dhu̯es- "smoke, spirit", attested in Baltic and Germanic words for "spook" and ultimately cognate with Latin fumus "smoke." The earliest attested form of the word is the Mycenaean Greek te-o (plural te-o-i), written in Linear B syllabic script. == Capitalization == The development of English orthography was dominated by Christian texts. Capitalized, "God" was first used to refer to the Abrahamic God and may now signify any monotheistic conception of God, including the translations of the Arabic Allāh, Persian Khuda, Indic Ishvara and the Maasai Ngai. In the English language, capitalization is used for names by which a god is known, including "God". Consequently, its capitalized form is not used for multiple gods or when referring to the generic idea of a deity. Pronouns referring to a god are also often capitalized by adherents to a religion as an indication of reverence, and are traditionally in the masculine gender ("He", "Him", "His" etc) unless specifically referring to a goddess. == See also == Anglo-Saxon paganism Bhagavan (Hindi word) El (deity) (Semitic word) Elohim Jumala (Finnish word) Tanri (Turkish word) Yahweh YHWH == References == == External links == Use of guþ n the Gothic Bible. Use of guda n the Gothic Bible. Gothic language and its relation to other Germanic languages such as Anglish (English) and Saxon Archived 2011-04-30 at the Wayback Machine

The English word god comes from the Old English god, which itself is derived from the Proto-Germanic *gudą. Its cognates in other Germanic languages include guþ, gudis (both Gothic), guð (Old Norse), god (Old Saxon, Old Frisian, and Old Dutch), and got (Old High German).

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Air for Free (wikipedia)

Air for Free is the eighth studio album by Relient K, released on July 22, 2016, through Mono vs Stereo. The album's lead single, "Bummin'", was released on April 13, 2016. It is the first album since Five Score and Seven Years Ago (2007) to feature drummer Dave Douglas, though he is not credited as an official member. It also features the return of producer Mark Lee Townsend following his absence on Collapsible Lung (2013). == Release and promotion == A week before its official release, Air for Free was streamed in its entirety on Pandora Radio. In support of the album, Relient K played an album-release show in their home state of Ohio on July 23, 2016, with Cardboard Kids opening, and later embarked on the Looking for America Tour with Switchfoot. The tour ran from September 16, beginning in Denver, Colorado, through November 26, concluding in San Francisco, California. == Commercial performance == Air for Free debuted at its peak of No. 44 on the Billboard 200 and also No. 1 album on the Top Christian Albums Chart, selling 9,000 copies in its opening week. == Critical reception == The album was met with critical acclaim. Writing for Jesus Freak Hideout, Michael Weaver states, "Air for Free could be described as what Collapsible Lung should've been"; in a similar vein, Cortney Warner declares that the album "proves the band is far from 'has been' status, and continues to create fresh, thoughtful music that anyone can enjoy." In his review for CM Addict, Michael Tackett says, "Air for Free is lyrically and musically a welcome return to form for Relient K." Writing for AllMusic, Neil Z. Yeung called the album a "lush and joyful affair" featuring a "sunny, creative blend of indie rock and contemporary pop." == Track listing == Vinyl == Personnel == Credits adapted from the album's liner notes. == Charts == == Release history == Sources: Amazon.com, SMLXL Vinyl == References == == External links == Official website

Air for Free is the eighth studio album by Relient K, released on July 22, 2016, through Mono vs Stereo. The album's lead single, "Bummin'", was released on April 13, 2016. It is the first album since Five Score and Seven Years Ago (2007) to feature drummer Dave Douglas, though he is not credited as an official member. It also features the return of producer Mark Lee Townsend following his absence on Collapsible Lung (2013).