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Two or more antidepressants taken together, from either the same or different classes (affecting the same area of the brain, often at a much higher level).
An antipsychotic combined with an antidepressant, particularly atypical antipsychotics such as aripiprazole (Abilify), quetiapine (Seroquel), olanzapine (Zyprexa),... | Antidepressant | Wikipedia | 433 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
Before the 1950s, opioids and amphetamines were commonly used as antidepressants. Amphetamine has been described as the first antidepressant. Use of opioids and amphetamines for depression was later restricted due to their addictive nature and side effects. Extracts from the herb St John's wort have been used as a "ner... | Antidepressant | Wikipedia | 362 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
In 1952, learning of the stimulating side effects of isoniazid, the Cincinnati psychiatrist Max Lurie tried it on his patients. In the following year, he and Harry Salzer reported that isoniazid improved depression in two-thirds of their patients, so they then coined the term antidepressant to refer to its action. A si... | Antidepressant | Wikipedia | 457 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
Attempting to improve the effectiveness of chlorpromazine, Kuhn in conjunction with the Geigy Pharmaceutical Company discovered the compound "G 22355", later renamed imipramine. Imipramine had a beneficial effect on patients with depression who showed mental and motor retardation. Kuhn described his new compound as a... | Antidepressant | Wikipedia | 492 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
Rapid-acting antidepressants
Esketamine (brand name Spravato), the first rapid-acting antidepressant to be approved for clinical treatment of depression, was introduced for this indication in March 2019 in the United States.
Research
A 2016 randomized controlled trial evaluated the rapid antidepressant effects of the ... | Antidepressant | Wikipedia | 508 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
According to National Institute for Health and Care Excellence (NICE) guidelines, antidepressants for children and adolescents with depression and obsessive-compulsive disorder (OCD) should be prescribed together with therapy and after being assessed by a child and adolescent psychiatrist. However, between 2006 and 201... | Antidepressant | Wikipedia | 413 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
Social science perspective
Some academics have highlighted the need to examine the use of antidepressants and other medical treatments in cross-cultural terms, because various cultures prescribe and observe different manifestations, symptoms, meanings, and associations of depression and other medical conditions within ... | Antidepressant | Wikipedia | 402 | 2388 | https://en.wikipedia.org/wiki/Antidepressant | Biology and health sciences | Psychiatric drugs | Health |
An anode usually is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, which is usually an electrode of the device through which conventional current leaves the device. A common mnemonic is ACID, for "anode current into device". The directi... | Anode | Wikipedia | 347 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
In general, if the current through the electrodes reverses direction, as occurs for example in a rechargeable battery when it is being charged, the roles of the electrodes as anode and cathode are reversed. However, the definition of anode and cathode is different for electrical devices such as diodes and vacuum tubes ... | Anode | Wikipedia | 503 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
In battery engineering, it is common to designate one electrode of a rechargeable battery the anode and the other the cathode according to the roles the electrodes play when the battery is discharged. This is despite the fact that the roles are reversed when the battery is charged. When this is done, "anode" simply des... | Anode | Wikipedia | 356 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
The use of 'East' to mean the 'in' direction (actually 'in' → 'East' → 'sunrise' → 'up') may appear contrived. Previously, as related in the first reference cited above, Faraday had used the more straightforward term "eisode" (the doorway where the current enters). His motivation for changing it to something meaning 't... | Anode | Wikipedia | 463 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
Electrolytic anode
In electrochemistry, the anode is where oxidation occurs and is the positive polarity contact in an electrolytic cell. At the anode, anions (negative ions) are forced by the electrical potential to react chemically and give off electrons (oxidation) which then flow up and into the driving circuit. Mn... | Anode | Wikipedia | 512 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
Vacuum tube anode
In electronic vacuum devices such as a cathode-ray tube, the anode is the positively charged electron collector. In a tube, the anode is a charged positive plate that collects the electrons emitted by the cathode through electric attraction. It also accelerates the flow of these electrons.
Diode a... | Anode | Wikipedia | 503 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
A less obvious example of this type of protection is the process of galvanising iron. This process coats iron structures (such as fencing) with a coating of zinc metal. As long as the zinc remains intact, the iron is protected from the effects of corrosion. Inevitably, the zinc coating becomes breached, either by cra... | Anode | Wikipedia | 337 | 2392 | https://en.wikipedia.org/wiki/Anode | Physical sciences | Electrochemistry | Chemistry |
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
Analog signals vary over a continuous range of possible values which m... | Analog television | Wikipedia | 424 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
Broadcasters of analog television encode their signal using different systems. The official systems of transmission were defined by the ITU in 1961 as: A, B, C, D, E, F, G, H, I, K, K1, L, M and N. These systems determine the number of scan lines, frame rate, channel width, video bandwidth, video-audio separation, and ... | Analog television | Wikipedia | 508 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
In principle, all three color encoding systems can be used with any scan line/frame rate combination. Therefore, in order to describe a given signal completely, it is necessary to quote the color system plus the broadcast standard as a capital letter. For example, the United States, Canada, Mexico and South Korea used ... | Analog television | Wikipedia | 453 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
When analog television was developed, no affordable technology for storing video signals existed; the luminance signal had to be generated and transmitted at the same time at which it is displayed on the CRT. It was therefore essential to keep the raster scanning in the camera (or other device for producing the signal... | Analog television | Wikipedia | 504 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
Extracting the sound
At this point the IF signal consists of a video carrier signal at one frequency and the sound carrier at a fixed offset in frequency. A demodulator recovers the video signal. Also at the output of the same demodulator is a new frequency modulated sound carrier at the offset frequency. In some sets ... | Analog television | Wikipedia | 450 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The front porch is a brief (about 1.5 microsecond) period inserted between the end of each transmitted line of picture and the leading edge of the next line's sync pulse. Its purpose was to allow voltage levels to stabilise in older televisions, preventing interference between picture lines. The front porch is the firs... | Analog television | Wikipedia | 474 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
Instead, the RGB signals are converted into YUV form, where the Y signal represents the luminance of the colors in the image. Because the rendering of colors in this way is the goal of both monochrome film and television systems, the Y signal is ideal for transmission as the luminance signal. This ensures a monochrome ... | Analog television | Wikipedia | 437 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The R, G, and B signals in the receiver needed for the display device (CRT, Plasma display, or LCD display) are electronically derived by matrixing as follows: R is the additive combination of (R-Y) with Y, G is the additive combination of (G-Y) with Y, and B is the additive combination of (B-Y) with Y. All of this is ... | Analog television | Wikipedia | 381 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
A small sample of the subcarrier, the colorburst, is included in the horizontal blanking portion, which is not visible on the screen. This is necessary to give the receiver a phase reference for the modulated signal. Under quadrature amplitude modulation the modulated chrominance signal changes phase as compared to it... | Analog television | Wikipedia | 474 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The above process uses the subcarrier. But as previously mentioned, it was deleted before transmission, and only the chroma is transmitted. Therefore, the receiver must reconstitute the subcarrier. For this purpose, a short burst of the subcarrier, known as the colorburst, is transmitted during the back porch (re-trace... | Analog television | Wikipedia | 431 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
In some analog color CRT displays, starting in 1956, the brightness control signal (luminance) is fed to the cathode connections of the electron guns, and the color difference signals (chrominance signals) are fed to the control grids connections. This simple CRT matrix mixing technique was replaced in later solid sta... | Analog television | Wikipedia | 458 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The vertical sync signal is a series of much longer pulses, indicating the start of a new field. The sync pulses occupy the whole line interval of a number of lines at the beginning and end of a scan; no picture information is transmitted during vertical retrace. The pulse sequence is designed to allow horizontal sync ... | Analog television | Wikipedia | 426 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The free-running oscillation of the horizontal circuit is especially critical, as the horizontal deflection circuits typically power the flyback transformer (which provides acceleration potential for the CRT) as well as the filaments for the high voltage rectifier tube and sometimes the filament(s) of the CRT itself. W... | Analog television | Wikipedia | 510 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
Other technical information
Components of a television system
The tuner is the object which, with the aid of an antenna, isolates the television signals received over the air. There are two types of tuners in analog television, VHF and UHF tuners. The VHF tuner selects the VHF television frequency. This consists of a... | Analog television | Wikipedia | 499 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The vertical sync signal is a series of much longer pulses, indicating the start of a new field. The vertical sync pulses occupy the whole of line interval of a number of lines at the beginning and end of a scan; no picture information is transmitted during vertical retrace. The pulse sequence is designed to allow hori... | Analog television | Wikipedia | 452 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
In an analog receiver with a CRT display sync pulses are fed to horizontal and vertical timebase circuits (commonly called sweep circuits in the United States), each consisting of an oscillator and an amplifier. These generate modified sawtooth and parabola current waveforms to scan the electron beam. Engineered wave... | Analog television | Wikipedia | 442 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
This voltage is not directly produced by the main power supply circuitry; instead, the receiver makes use of the circuitry used for horizontal scanning. Direct current (DC), is switched through the line output transformer, and alternating current (AC) is induced into the scan coils. At the end of each horizontal scan l... | Analog television | Wikipedia | 427 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
The first country to make a wholesale switch to digital over-the-air (terrestrial television) broadcasting was Luxembourg in 2006, followed later in 2006 by the Netherlands. The Digital television transition in the United States for high-powered transmission was completed on 12 June 2009, the date that the Federal Comm... | Analog television | Wikipedia | 410 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
In Malaysia, the Malaysian Communications and Multimedia Commission advertised for tender bids to be submitted in the third quarter of 2009 for the 470 through 742 MHz UHF allocation, to enable Malaysia's broadcast system to move into DTV. The new broadcast band allocation would result in Malaysia's having to build an... | Analog television | Wikipedia | 401 | 2393 | https://en.wikipedia.org/wiki/Analog%20television | Technology | Broadcasting | null |
Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation.
The use of adhesives offers certain advantages over other binding techniques such as sewing, mechanical fastenings, and we... | Adhesive | Wikipedia | 456 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Although sticky enough, plant-based, single-component adhesives can be brittle and vulnerable to environmental conditions. The first use of compound adhesives was discovered in Sibudu, South Africa. Here, 70,000-year-old stone segments that were once inserted in axe hafts were discovered covered with an adhesive compos... | Adhesive | Wikipedia | 395 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
The first references to adhesives in literature appeared in approximately 2000 BC. Further historical records of adhesive use are found from the period spanning 1500–1000 BC. Artifacts from this period include paintings depicting wood gluing operations and a casket made of wood and glue in King Tutankhamun's tomb. Othe... | Adhesive | Wikipedia | 378 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
In Europe, glue fell into disuse until the period AD 1500–1700. At this time, world-renowned cabinet and furniture makers such as Thomas Chippendale and Duncan Phyfe began to use adhesives to hold their products together. In 1690, the first commercial glue plant was established in The Netherlands. This plant produced g... | Adhesive | Wikipedia | 456 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
The 1920s, 1930s, and 1940s witnessed great advances in the development and production of new plastics and resins due to the First and Second World Wars. These advances greatly improved the development of adhesives by allowing the use of newly developed materials that exhibited a variety of properties. With changing ne... | Adhesive | Wikipedia | 476 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
PSAs are designed for either permanent or removable applications. Examples of permanent applications include safety labels for power equipment, foil tape for HVAC duct work, automotive interior trim assembly, and sound/vibration damping films. Some high performance permanent PSAs exhibit high adhesion values and can su... | Adhesive | Wikipedia | 470 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Contact adhesives must be applied to both surfaces and allowed some time to dry before the two surfaces are pushed together. Some contact adhesives require as long as 24 hours to dry completely before the surfaces are to be held together. Once the surfaces are pushed together, the bond forms very quickly. Clamps are ty... | Adhesive | Wikipedia | 501 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Pre-mixed and frozen adhesives
Pre-mixed and frozen adhesives (PMFs) are adhesives that are mixed, deaerated, packaged, and frozen. As it is necessary for PMFs to remain frozen before use, once they are frozen at −80 °C they are shipped with dry ice and are required to be stored at or below −40 °C. PMF adhesives elimin... | Adhesive | Wikipedia | 452 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
One example is a simple paste made by cooking flour in water. Starch-based adhesives are used in corrugated board and paper sack production, paper tube winding, and wallpaper adhesives. Casein glue is mainly used to adhere glass bottle labels. Animal glues have traditionally been used in bookbinding, wood joining, and ... | Adhesive | Wikipedia | 495 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
In some cases, an actual chemical bond occurs between adhesive and substrate. Thiolated polymers, for example, form chemical bonds with endogenous proteins such as mucus glycoproteins, integrins or keratins via disulfide bridges. Because of their comparatively high adhesive properties, these polymers find numerous biom... | Adhesive | Wikipedia | 473 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Other types of fracture
Other types of fracture include:
The mixed type, which occurs if the crack propagates at some spots in a cohesive and in others in an interfacial manner. Mixed fracture surfaces can be characterised by a certain percentage of adhesive and cohesive areas.
The alternating crack path type which o... | Adhesive | Wikipedia | 488 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Increasing the joint resistance is usually obtained by designing its geometry so that:
The bonded zone is large
It is mainly loaded in mode II
Stable crack propagation will follow the appearance of a local failure.
Shelf life
Some glues and adhesives have a limited shelf life. Shelf life is dependent on multiple fa... | Adhesive | Wikipedia | 99 | 2396 | https://en.wikipedia.org/wiki/Adhesive | Technology | Material and chemical | null |
Analytical chemistry studies and uses instruments and methods to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative analysis identifies analytes, while quantit... | Analytical chemistry | Wikipedia | 454 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Starting in the 1970s, analytical chemistry became progressively more inclusive of biological questions (bioanalytical chemistry), whereas it had previously been largely focused on inorganic or small organic molecules. Lasers have been increasingly used as probes and even to initiate and influence a wide variety of rea... | Analytical chemistry | Wikipedia | 499 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Quantitative analysis is the measurement of the quantities of particular chemical constituents present in a substance. Quantities can be measured by mass (gravimetric analysis) or volume (volumetric analysis).
Gravimetric analysis
The gravimetric analysis involves determining the amount of material present by weighi... | Analytical chemistry | Wikipedia | 378 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Mass spectrometry measures mass-to-charge ratio of molecules using electric and magnetic fields. In a mass spectrometer, a small amount of sample is ionized and converted to gaseous ions, where they are separated and analyzed according to their mass-to-charge ratios. There are several ionization methods: electron ioniz... | Analytical chemistry | Wikipedia | 368 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Chromatography can be used to determine the presence of substances in a sample as different components in a mixture have different tendencies to adsorb onto the stationary phase or dissolve in the mobile phase. Thus, different components of the mixture move at different speed. Different components of a mixture can ther... | Analytical chemistry | Wikipedia | 506 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Devices that integrate (multiple) laboratory functions on a single chip of only millimeters to a few square centimeters in size and that are capable of handling extremely small fluid volumes down to less than picoliters.
Errors
Error can be defined as numerical difference between observed value and true value. The e... | Analytical chemistry | Wikipedia | 447 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Standard addition
The method of standard addition is used in instrumental analysis to determine the concentration of a substance (analyte) in an unknown sample by comparison to a set of samples of known concentration, similar to using a calibration curve. Standard addition can be applied to most analytical techniques ... | Analytical chemistry | Wikipedia | 478 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Noise reduction
Noise reduction can be accomplished either in computer hardware or software. Examples of hardware noise reduction are the use of shielded cable, analog filtering, and signal modulation. Examples of software noise reduction are digital filtering, ensemble average, boxcar average, and correlation methods... | Analytical chemistry | Wikipedia | 487 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
Analytical chemistry has played a critical role in the understanding of basic science to a variety of practical applications, such as biomedical applications, environmental monitoring, quality control of industrial manufacturing, forensic science, and so on.
The recent developments in computer automation and informati... | Analytical chemistry | Wikipedia | 180 | 2408 | https://en.wikipedia.org/wiki/Analytical%20chemistry | Physical sciences | Analytical chemistry | null |
An analog computer or analogue computer is a type of computation machine (computer) that uses physical phenomena such as electrical, mechanical, or hydraulic quantities behaving according to the mathematical principles in question (analog signals) to model the problem being solved. In contrast, digital computers repres... | Analog computer | Wikipedia | 450 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use.
The planisphere was first described by Ptolemy in the 2nd century AD. The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination o... | Analog computer | Wikipedia | 395 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
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 James Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of t... | Analog computer | Wikipedia | 460 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
World War II era gun directors, gun data computers, and bomb sights used mechanical analog computers. In 1942 Helmut Hölzer built a fully electronic analog computer at Peenemünde Army Research Center as an embedded control system (mixing device) to calculate V-2 rocket trajectories from the accelerations and orientatio... | Analog computer | Wikipedia | 346 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Educational analog computers illustrated the principles of analog calculation. The Heathkit EC-1, a $199 educational analog computer, was made by the Heath Company, US . It was programmed using patch cords that connected nine operational amplifiers and other components. General Electric also marketed an "educational" a... | Analog computer | Wikipedia | 479 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
By contrast, it is very inexpensive to build an electrical equivalent of a complex mechanical system, to simulate its behavior. Engineers arrange a few operational amplifiers (op amps) and some passive linear components to form a circuit that follows the same equations as the mechanical system being simulated. All meas... | Analog computer | Wikipedia | 494 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
The precision of the analog computer readout was limited chiefly by the precision of the readout equipment used, generally three or four significant figures. (Modern digital simulations are much better in this area. Digital arbitrary-precision arithmetic can provide any desired degree of precision.) However, in most ca... | Analog computer | Wikipedia | 346 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Signal sources: These are blocks that generate analog signals, such as voltage or current, to represent input data and operations.
Amplifiers: Amplifiers are used to boost analog signals and maintain their amplitudes throughout the system. They amplify weak input signals and compensate for signal losses during transmis... | Analog computer | Wikipedia | 480 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Output devices in analog machines can vary depending on the specific goals of the system. For example, they could be graphical indicators, oscilloscopes, graphic recording devices, TV connection module, voltmeter, etc. These devices allow for the visualization of analog signals and the representation of the results of ... | Analog computer | Wikipedia | 443 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
After 1980, purely digital computers progressed more and more rapidly and were fast enough to compete with analog computers.
One key to the speed of analog computers was their fully parallel computation, but this was also a limitation. The more equations required for a problem, the more analog components were needed, e... | Analog computer | Wikipedia | 508 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Coordinate conversion from polar to rectangular was done by a mechanical resolver (called a "component solver" in US Navy fire control computers). Two discs on a common axis positioned a sliding block with pin (stubby shaft) on it. One disc was a face cam, and a follower on the block in the face cam's groove set the ra... | Analog computer | Wikipedia | 487 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
At any distance along the adjacent side, a line perpendicular to it intersects the hypotenuse at a particular point. The distance between that point and the adjacent side is some fraction that is the product of 1 the distance from the vertex, and 2 the magnitude of the opposite side.
The second input variable in this ... | Analog computer | Wikipedia | 460 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Although they did not accomplish any computation, electromechanical position servos (aka. torque amplifiers) were essential in mechanical analog computers of the "rotating-shaft" type for providing operating torque to the inputs of subsequent computing mechanisms, as well as driving output data-transmission devices suc... | Analog computer | Wikipedia | 512 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Electrical elements such as inductors and capacitors used in electrical analog computers had to be carefully manufactured to reduce non-ideal effects. For example, in the construction of AC power network analyzers, one motive for using higher frequencies for the calculator (instead of the actual power frequency) was th... | Analog computer | Wikipedia | 490 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Key electrical/electronic components might include:
precision resistors and capacitors
operational amplifiers
multipliers
potentiometers
fixed-function generators
The core mathematical operations used in an electric analog computer are:
addition
integration with respect to time
inversion
multiplication
expon... | Analog computer | Wikipedia | 385 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
With the development of very-large-scale integration (VLSI) technology, Yannis Tsividis' group at Columbia University has been revisiting analog/hybrid computers design in standard CMOS process. Two VLSI chips have been developed, an 80th-order analog computer (250 nm) by Glenn Cowan in 2005 and a 4th-order hybrid comp... | Analog computer | Wikipedia | 391 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
Analog Paradim, a modular analog computer produced by anabrid
Boeing B-29 Superfortress Central Fire Control System
Deltar
E6B flight computer
Ishiguro Storm Surge Computer
Kerrison Predictor
Leonardo Torres y Quevedo's Analogue Calculating Machines based on "fusee sans fin"
Librascope, aircraft weight and balan... | Analog computer | Wikipedia | 286 | 2428 | https://en.wikipedia.org/wiki/Analog%20computer | Technology | Computer hardware | null |
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn, or complete rotation, one arcminute is of a turn. The nautical mile (nmi) was originally defined as the arc length of a minute of latitude on... | Minute and second of arc | Wikipedia | 492 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
One arcminute is the approximate distance two contours can be separated by, and still be distinguished by, a person with 20/20 vision.
One arcsecond is the approximate angle subtended by a U.S. dime coin (18 mm) at a distance of . An arcsecond is also the angle subtended by
an object of diameter at a distance of one... | Minute and second of arc | Wikipedia | 507 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
Contrary to what one might assume, minutes and seconds of arc do not directly relate to minutes and seconds of time, in either the rotational frame of the Earth around its own axis (day), or the Earth's rotational frame around the Sun (year). The Earth's rotational rate around its own axis is 15 minutes of arc per minu... | Minute and second of arc | Wikipedia | 418 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
Apart from the Sun, the star with the largest angular diameter from Earth is R Doradus, a red giant with a diameter of 0.05″. Because of the effects of atmospheric blurring, ground-based telescopes will smear the image of a star to an angular diameter of about 0.5″; in poor conditions this increases to 1.5″ or even mor... | Minute and second of arc | Wikipedia | 447 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
Related to cartography, property boundary surveying using the metes and bounds system and cadastral surveying relies on fractions of a degree to describe property lines' angles in reference to cardinal directions. A boundary "mete" is described with a beginning reference point, the cardinal direction North or South fol... | Minute and second of arc | Wikipedia | 363 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
For example, if the point of impact is 3 inches high and 1.5 inches left of the point of aim at 100 yards (which for instance could be measured by using a spotting scope with a calibrated reticle, or a target delineated for such purposes), the scope needs to be adjusted 3 MOA down, and 1.5 MOA right. Such adjustments ... | Minute and second of arc | Wikipedia | 358 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
One thing to be aware of is that some MOA scopes, including some higher-end models, are calibrated such that an adjustment of 1 MOA on the scope knobs corresponds to exactly 1 inch of impact adjustment on a target at 100 yards, rather than the mathematically correct 1.047 inches. This is commonly known as the Shooter's... | Minute and second of arc | Wikipedia | 471 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
Rifle manufacturers and gun magazines often refer to this capability as sub-MOA, meaning a gun consistently shooting groups under 1 MOA. This means that a single group of 3 to 5 shots at 100 yards, or the average of several groups, will measure less than 1 MOA between the two furthest shots in the group, i.e. all shot... | Minute and second of arc | Wikipedia | 497 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
1′ at 100 yards is about 1.047 inches
1′ ≈ 0.291 mrad (or 29.1 mm at 100 m, approximately 30 mm at 100 m)
1 mrad ≈ 3.44′, so mrad ≈ ′
0.1 mrad equals exactly 1 cm at 100 m, or exactly 0.36 inches at 100 yards
Human vision
In humans, 20/20 vision is the ability to resolve a spatial pattern separated by a visual an... | Minute and second of arc | Wikipedia | 245 | 2431 | https://en.wikipedia.org/wiki/Minute%20and%20second%20of%20arc | Physical sciences | Angle | Basics and measurement |
In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Acceleration is one of several components of kinematics, the study of motion. Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the o... | Acceleration | Wikipedia | 490 | 2443 | https://en.wikipedia.org/wiki/Acceleration | Physical sciences | Classical mechanics | null |
Instantaneous acceleration, meanwhile, is the limit of the average acceleration over an infinitesimal interval of time. In the terms of calculus, instantaneous acceleration is the derivative of the velocity vector with respect to time:
As acceleration is defined as the derivative of velocity, , with respect to time a... | Acceleration | Wikipedia | 482 | 2443 | https://en.wikipedia.org/wiki/Acceleration | Physical sciences | Classical mechanics | null |
a unit vector tangent to the path pointing in the direction of motion at the chosen moment in time. Taking into account both the changing speed and the changing direction of , the acceleration of a particle moving on a curved path can be written using the chain rule of differentiation for the product of two functions ... | Acceleration | Wikipedia | 421 | 2443 | https://en.wikipedia.org/wiki/Acceleration | Physical sciences | Classical mechanics | null |
In uniform circular motion, that is moving with constant speed along a circular path, a particle experiences an acceleration resulting from the change of the direction of the velocity vector, while its magnitude remains constant. The derivative of the location of a point on a curve with respect to time, i.e. its veloci... | Acceleration | Wikipedia | 481 | 2443 | https://en.wikipedia.org/wiki/Acceleration | Physical sciences | Classical mechanics | null |
The sign of the tangential component of the acceleration is determined by the sign of the angular acceleration (), and the tangent is always directed at right angles to the radius vector.
Coordinate systems
In multi-dimensional Cartesian coordinate systems, acceleration is broken up into components that correspond wi... | Acceleration | Wikipedia | 341 | 2443 | https://en.wikipedia.org/wiki/Acceleration | Physical sciences | Classical mechanics | null |
Apoptosis (from ) is a form of programmed cell death that occurs in multicellular organisms and in some eukaryotic, single-celled microorganisms such as yeast. Biochemical events lead to characteristic cell changes (morphology) and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin ... | Apoptosis | Wikipedia | 463 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
German scientist Carl Vogt was first to describe the principle of apoptosis in 1842. In 1885, anatomist Walther Flemming delivered a more precise description of the process of programmed cell death. However, it was not until 1965 that the topic was resurrected. While studying tissues using electron microscopy, John Ker... | Apoptosis | Wikipedia | 413 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
In Greek, apoptosis translates to the "falling off" of leaves from a tree. Cormack, professor of Greek language, reintroduced the term for medical use as it had a medical meaning for the Greeks over two thousand years before. Hippocrates used the term to mean "the falling off of the bones". Galen extended its meaning t... | Apoptosis | Wikipedia | 469 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
A cell initiates intracellular apoptotic signaling in response to a stress, which may bring about cell death. The binding of nuclear receptors by glucocorticoids, heat, radiation, nutrient deprivation, viral infection, hypoxia, increased intracellular concentration of free fatty acids and increased intracellular calciu... | Apoptosis | Wikipedia | 462 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
During apoptosis, cytochrome c is released from mitochondria through the actions of the proteins Bax and Bak. The mechanism of this release is enigmatic, but appears to stem from a multitude of Bax/Bak homo- and hetero-dimers of Bax/Bak inserted into the outer membrane. Once cytochrome c is released it binds with Apopt... | Apoptosis | Wikipedia | 382 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
TNF pathway
TNF-alpha is a cytokine produced mainly by activated macrophages, and is the major extrinsic mediator of apoptosis. Most cells in the human body have two receptors for TNF-alpha: TNFR1 and TNFR2. The binding of TNF-alpha to TNFR1 has been shown to initiate the pathway that leads to caspase activation via t... | Apoptosis | Wikipedia | 500 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Following TNF-R1 and Fas activation in mammalian cells a balance between proapoptotic (BAX, BID, BAK, or BAD) and anti-apoptotic (Bcl-Xl and Bcl-2) members of the Bcl-2 family are established. This balance is the proportion of proapoptotic homodimers that form in the outer-membrane of the mitochondrion. The proapoptoti... | Apoptosis | Wikipedia | 489 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Negative regulators of apoptosis
Negative regulation of apoptosis inhibits cell death signaling pathways, helping tumors to evade cell death and developing drug resistance. The ratio between anti-apoptotic (Bcl-2) and pro-apoptotic (Bax) proteins determines whether a cell lives or dies. Many families of proteins act a... | Apoptosis | Wikipedia | 476 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Before the apoptotic cell is disposed of, there is a process of disassembly. There are three recognized steps in apoptotic cell disassembly:
Membrane blebbing: The cell membrane shows irregular buds known as blebs. Initially these are smaller surface blebs. Later these can grow into larger so-called dynamic membrane b... | Apoptosis | Wikipedia | 449 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Pathway knock-outs
Many knock-outs have been made in the apoptosis pathways to test the function of each of the proteins. Several caspases, in addition to APAF1 and FADD, have been mutated to determine the new phenotype. In order to create a tumor necrosis factor (TNF) knockout, an exon containing the nucleotides 370... | Apoptosis | Wikipedia | 396 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
The caspase proteins are integral parts of the apoptosis pathway, so it follows that knock-outs made have varying damaging results. A caspase 9 knock-out leads to a severe brain malformation . A caspase 8 knock-out leads to cardiac failure and thus embryonic lethality . However, with the use of cre-lox technology, a... | Apoptosis | Wikipedia | 293 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Label-free live cell imaging, time-lapse microscopy, flow fluorocytometry, and transmission electron microscopy can be used to compare apoptotic and necrotic cells. There are also various biochemical techniques for analysis of cell surface markers (phosphatidylserine exposure versus cell permeability by flow cytometry... | Apoptosis | Wikipedia | 431 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
A recently described example of this concept in action can be seen in the development of a lung cancer called NCI-H460. The X-linked inhibitor of apoptosis protein (XIAP) is overexpressed in cells of the H460 cell line. XIAPs bind to the processed form of caspase-9 and suppress the activity of apoptotic activator cytoc... | Apoptosis | Wikipedia | 386 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
Inhibition
Inhibition of apoptosis can result in a number of cancers, inflammatory diseases, and viral infections. It was originally believed that the associated accumulation of cells was due to an increase in cellular proliferation, but it is now known that it is also due to a decrease in cell death. The most common o... | Apoptosis | Wikipedia | 374 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
The main method of treatment for potential death from signaling-related diseases involves either increasing or decreasing the susceptibility of apoptosis in diseased cells, depending on whether the disease is caused by either the inhibition of or excess apoptosis. For instance, treatments aim to restore apoptosis to tr... | Apoptosis | Wikipedia | 300 | 2457 | https://en.wikipedia.org/wiki/Apoptosis | Biology and health sciences | Cell processes | Biology |
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