text:
Constructive empiricism

In philosophy of science, constructive empiricism is a form of empiricism. While it is sometimes referred to as an empiricist form of structuralism, its main proponent, Bas van Fraassen, has consistently distinguished between the two views.

Overview
Bas van Fraassen is nearly solely responsible for the initial development of constructive empiricism; its historically most important presentation appears in his The Scientific Image (1980). Constructive empiricism states that scientific theories are semantically literal, that they aim to be empirically adequate, and that their acceptance involves, as belief, only that they are empirically adequate. A theory is empirically adequate if and only if everything that it says about observable entities is true (regardless of what it says about unobservable entities). A theory is semantically literal if and only if the language of the theory is interpreted in such a way that the claims of the theory are either true or false (as opposed to an instrumentalist reading).

Constructive empiricism is thus a normative, semantic and epistemological thesis. That science aims to be empirically adequate expresses the normative component. That scientific theories are semantically literal expresses the semantic component. That acceptance involves, as belief, only that a theory is empirically adequate expresses the epistemological component.

Constructive empiricism opposes scientific realism, logical positivism (or logical empiricism) and instrumentalism. Constructive empiricism and scientific realism agree that theories are semantically literal, which logical positivism and instrumentalism deny. Constructive empiricism, logical positivism and instrumentalism agree that theories do not aim for truth about unobservables, which scientific realism denies.

Constructive empiricism has been used to analyze various scientific fields, from physics to psychology (especially computational psychology).

title: Constructive empiricism


text:
Recirculating ball

Recirculating ball, also known as recirculating ball and nut or worm and sector, is a steering mechanism commonly found in older automobiles, off-road vehicles, and some trucks. Most newer cars use the more economical rack and pinion steering instead, but some upmarket manufacturers (such as BMW and Mercedes-Benz) held on to the design until well into the 1990s for the durability and strength inherent in the design. A few, including Chrysler, General Motors, Lada and Ineos, still use this technology in certain models including the Jeep Wrangler, the Ineos Grenadier Quartermaster and the Lada Niva.

Mechanism
The recirculating ball steering mechanism contains a worm gear inside a block with a threaded hole in it; this block has gear teeth cut into the outside to engage the sector shaft (also called a sector gear) which moves the Pitman arm. The steering wheel connects to a shaft, which rotates the worm gear inside of the block. Instead of twisting further into the block, the worm gear is fixed so that when it rotates, it moves the block, which transmits the motion through the gear to the Pitman arm, causing the roadwheels to turn.

Bearing balls
The worm gear is similar in design to a ball screw; the threads are filled with steel balls that recirculate through the gear and rack as it turns. The balls serve to reduce friction and wear in the gear, and reduce slop. Slop, when the gears come out of contact with each other, would be felt when changing the direction of the steering wheel, causing the wheel to feel loose.

Power assistance
Power steering in a recirculating-ball system works similarly to that in a rack-and-pinion system. Assistance is provided by supplying higher-pressure fluid to one side of the block.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Recirculating ball


text:
MESFET

A MESFET (metal–semiconductor field-effect transistor) is a field-effect transistor semiconductor device similar to a JFET with a Schottky (metal–semiconductor) junction instead of a p–n junction for a gate.

Construction
MESFETs are constructed in compound semiconductor technologies lacking high quality surface passivation, such as gallium arsenide, indium phosphide, or silicon carbide, and are faster but more expensive than silicon-based JFETs or MOSFETs. Production MESFETs are operated up to approximately 45 GHz, and are commonly used for microwave frequency communications and radar. The first MESFETs were developed in 1966, and a year later their extremely high frequency RF microwave performance was demonstrated.

Functional architecture
The MESFET, similarly to JFET, differs from the common insulated-gate FET or MOSFET in that there is no insulator under the gate over the active switching region. This implies that the MESFET gate should, in transistor mode, be biased such that one has a reversed-biased depletion zone controlling the underlying channel, rather than a forward-conducting metal–semiconductor diode to the channel.

While this restriction inhibits certain circuit possibilities as the gate must remain reverse-biased and cannot therefore exceed a certain voltage of forward bias, MESFETs analog and digital devices work reasonably well if kept within the confines of design limits. The most critical aspect of the design is the gate metal extent over the switching region. Generally the narrower the gate modulated carrier channel the better the frequency handling abilities, overall. Spacing of the source and drain with respect to the gate, and the lateral extent of the gate are important though somewhat less critical design parameters. MESFET current handling ability improves as the gate is elongated laterally, keeping the active region constant, however is limited by phase shift along the gate due to the transmission line effect. As a result, most production MESFETs use a built up top layer of low resistance metal on the gate, often producing a mushroom-like profile in cross section.

Applications
Numerous MESFET fabrication possibilities have been explored for a wide variety of semiconductor systems. Some of the main application areas are military communications, as front end low noise amplifier of microwave receivers in both military radar devices and communication, commercial optoelectronics, satellite communication, as power amplifier for output stage of microwave links, and as a power oscillator.

title: MESFET


text:
Talk:MESFET

FET split
splitup of article Field effect transistor in progress, please see Talk:Field effect transistor Pjacobi 15:30, 19 Jul 2004 (UTC)
 * Done Pjacobi 21:27, 19 Jul 2004 (UTC)

Why not Si?
Are there no Si MESFETs because it's impossible, or because Si JFETs or MOSFETs are good enough to fill the role that you'd otherwise want a MESFET for?--Joel 23:50, 21 March 2006 (UTC)

MESFETs aren't usually made in Si because the mobility and saturation velocity are significantly lower in Si than in other materials. See the last paragraph of http://ece-www.colorado.edu/~bart/book/mesfet.htm. Chrisfez 08:04, 16 May 2006 (UTC)

 * However, it is not at all impossible to make a fully functional Si MESFET. I've removed the text in the article that suggests such.  I'd think that Si MESFETs are rare simply because of the ubiquity of the Si MOSFET process and because very high-speed applications often lend themselves to certain III-V systems because of the aforementioned carrier mobility and saturation velocity advantages.  I'd also venture to guess that MESFETs are an increasingly rare construction with the improvement of generally superior heterojunction systems. (the obvious advantage of the MESFET being its very simple design) -- mattb

 * The Lepkowski ref for 45 GHz says Silicon MESFET. - Rod57 (talk) 13:37, 4 January 2016 (UTC)

Introductory paragraph, last sentence
This sentence is confusing. - 65.96.171.132  17 February 2011

 * if you mean "From a digital circuit design perspective, it is increasingly difficult to use MESFETs as the basis for digital integrated circuits as the scale of integration goes up, compared to CMOS silicon based fabrication" - I'd agree. Needs explanation and source. - Rod57 (talk) 13:43, 4 January 2016 (UTC)

India Education Program course assignment
This article was the subject of an educational assignment supported by Wikipedia Ambassadors through the India Education Program.

The above message was substituted from by PrimeBOT (talk) on 19:56, 1 February 2023 (UTC)

title: Talk:MESFET


text:
Heritage of Shannara

The Heritage of Shannara is a series of four fantasy novels by Terry Brooks, set hundreds of years after the original Shannara trilogy. Unlike the original trilogy, however, this series is all one, cohesive story, in contrast to the three isolated stories of the originals. It is set in a future Four Lands in which the Federation of the Southland has driven off the Elves, enslaved the Dwarves, and outlawed magic. Only the rebel Free-born, led by Padishar Creel, dare to resist. The series begins with The Scions of Shannara, when the Ohmsford descendants are summoned by the shade of Allanon to combat the Shadowen that have been poisoning the land, each charged with a quest only they can embark on. The story continues with The Druid of Shannara, The Elf Queen of Shannara, and concludes with The Talismans of Shannara.

The Scions of Shannara
The first novel in The Heritage of Shannara reveals the gathering of the chosen Ohmsfords to meet with the shade of Allanon, then focuses on Par and Coll Ohmsford as they attempt to retrieve the Sword of Shannara.

The Druid of Shannara
The second novel follows and mainly focuses on Walker Boh, as he reluctantly searches for the Black Elfstone, which has the power to restore the Druids and their keep, Paranor.

The Elf Queen of Shannara
The third novel chronicles Wren Ohmsford's travels beyond the shores of the Westland in search of the lost Elven race.

The Talismans of Shannara
The last novel details the final conflict between the Ohmsfords and the Shadowen monsters that have overtaken the Four Lands.

Main characters

 * Allanon
 * Axhind
 * Cogline
 * Coll Ohmsford
 * Damson Rhee
 * Ellenroh Elessedil, Queen of Elves
 * Faun (Shannara)
 * Garth (Shannara)
 * King of the Silver River
 * Matty Roh
 * Mole (Shannara)
 * Morgan Leah
 * Padishar Creel
 * Par Ohmsford
 * Pe Ell - assassin
 * Quickening - daughter of the King of the Silver River
 * Rimmer Dall
 * Rumor (Shannara)
 * Stresa (Shannara)
 * Steff (Shannara)
 * Shadowen
 * Teel
 * Triss (Shannara)
 * Walker Boh
 * Wren Elessedil

title: Heritage of Shannara


text:
WMNI

WMNI (920 AM) is a commercial radio station licensed to Columbus, Ohio, known as "Fox Sports 920" with a sports format. Locally owned by North American Broadcasting Company, Inc., WMNI serves the Columbus metropolitan area. WMNI's studios are located in Marble Cliff, Ohio, using a Columbus address, while the transmitter resides in Grove City. In addition to a standard analog transmission, WMNI is available online.

Programming
In addition to its sports talk format, WMNI carries a number of local and national sports events, including the Indy 500, the Brickyard 400, Notre Dame college football and Columbus Clippers Triple A baseball.

On Saturday and Sunday mornings, WMNI features talk shows such as "Plant Talk with Fred Hower" and "At Home With Gary Sullivan" as well as some paid brokered programming. WMNI carries news updates from Fox News Radio.

History
On April 26, 1958, WMNI first signed on the air. For most of its three decades, it had a full service, country radio format. As country music listening started to move from AM to FM in the 1980s, WMNI switched to a satellite-delivered adult standards format from Westwood One. By the late 1990s, much of the music was locally programmed using Columbus-based disc jockeys. As of August 2007, WMNI shifted back to Westwood One's "America's Best Music" format, a mix of soft oldies and standards.

On June 14, 2012 at 6:00 a.m., WMNI switched to a simulcast of WMNI-FM, which had flipped from a classic hits sound as WTDA-FM to a news format.

On July 18, 2013, the AM/FM simulcast ended, with WMNI returning to the soft oldies and adult standards format.

On June 12, 2017, WMNI changed their format from adult standards to soft adult contemporary music, branded as "Easy 95.1 & 920" (simulcast on FM translator W236CZ 95.1 FM Columbus).

On June 14, 2022, WMNI changed their format from soft adult contemporary to sports, branded as "Fox Sports 920", with programming from Fox Sports Radio. The 95.1 translator switched to a relay of sister station WJKR's HD2 subchannel.

title: WMNI


text:
High-electron-mobility transistor

A high-electron-mobility transistor (HEMT or HEM FET), also known as heterostructure FET (HFET) or modulation-doped FET (MODFET), is a field-effect transistor incorporating a junction between two materials with different band gaps (i.e. a heterojunction) as the channel instead of a doped region (as is generally the case for a MOSFET). A commonly used material combination is GaAs with AlGaAs, though there is wide variation, dependent on the application of the device. Devices incorporating more indium generally show better high-frequency performance, while in recent years, gallium nitride HEMTs have attracted attention due to their high-power performance.

Like other FETs, HEMTs can be used in integrated circuits as digital on-off switches. FETs can also be used as amplifiers for large amounts of current using a small voltage as a control signal. Both of these uses are made possible by the FET’s unique current–voltage characteristics. HEMT transistors are able to operate at higher frequencies than ordinary transistors, up to millimeter wave frequencies, and are used in high-frequency products such as cell phones, satellite television receivers, voltage converters, and radar equipment. They are widely used in satellite receivers, in low power amplifiers and in the defense industry.

Applications
The applications of HEMTs include microwave and millimeter wave communications, imaging, radar, radio astronomy, and power switching. They are found in many types of equipment ranging from cellphones, power supply adapters and DBS receivers to radio astronomy and electronic warfare systems such as radar systems. Numerous companies worldwide develop, manufacture, and sell HEMT-based devices in the form of discrete transistors, as 'monolithic microwave integrated circuits' (MMICs), or within power switching integrated circuits.

HEMTs are suitable for applications where high gain and low noise at high frequencies are required, as they have shown current gain to frequencies greater than 600 GHz and power gain to frequencies greater than 1THz. Gallium nitride based HEMTs are used as power switching transistors for voltage converter applications due to their low on-state resistances, low switching losses, and high breakdown strength. These gallium nitride enhanced voltage converter applications include AC adapters, which benefit from smaller package sizes due to the power circuitry requiring smaller passive electronic components.

History
The invention of the high-electron-mobility transistor (HEMT) is usually attributed to physicist Takashi Mimura (三村 高志), while working at Fujitsu in Japan. The basis for the HEMT was the GaAs (gallium arsenide) MOSFET (metal–oxide–semiconductor field-effect transistor), which Mimura had been researching as an alternative to the standard silicon (Si) MOSFET since 1977. He conceived the HEMT in Spring 1979, when he read about a modulated-doped heterojunction superlattice developed at Bell Labs in the United States, by Ray Dingle, Arthur Gossard and Horst Störmer who filed a patent in April 1978. Mimura filed a patent disclosure for a HEMT in August 1979, and then a patent later that year. The first demonstration of a HEMT device, the D-HEMT, was presented by Mimura and Satoshi Hiyamizu in May 1980, and then they later demonstrated the first E-HEMT in August 1980.

Independently, Daniel Delagebeaudeuf and Tranc Linh Nuyen, while working at Thomson-CSF in France, filed a patent for a similar type of field-effect transistor in March 1979. It also cites the Bell Labs patent as an influence. The first demonstration of an "inverted" HEMT was presented by Delagebeaudeuf and Nuyen in August 1980.

One of the earliest mentions of a GaN-based HEMT is in the 1993 Applied Physics Letters article, by Khan et al. Later, in 2004, P.D. Ye and B. Yang et al demonstrated a GaN (gallium nitride) metal–oxide–semiconductor HEMT (MOS-HEMT). It used atomic layer deposition (ALD) aluminum oxide (Al2O3) film both as a gate dielectric and for surface passivation.

Operation
Field effect transistors whose operation relies on the formation of a two-dimensional electron gas (2DEG) are known as HEMTs. In HEMTS electric current flows between a drain and source element via the 2DEG, which is located at the interface between two layers of differing band gaps, termed the heterojunction. Some examples of previously explored heterojunction layer compositions (heterostructures) for HEMTs include AlGaN/GaN, AlGaAs/GaAs, InGaAs/GaAs, and Si/SiGe.

Advantages
The advantages of HEMTs over other transistor topologies like the Bipolar junction transistor and the MOSFET are higher operating temperatures of GaN-based HEMTs compared to Si-based MOSFETS, higher breakdown strengths in the case of GaN-based HEMTs versus Si-based MOSFETS, lower specific on-state resistances when comparing GaN-based HEMTs to Si-based MOSFETs, and low noise performance/higher switching speeds in the case of InP HEMTs.

2DEG channel creation
The wide band element is doped with donor atoms; thus it has excess electrons in its conduction band. These electrons will diffuse to the adjacent narrow band material’s conduction band due to the availability of states with lower energy. The movement of electrons will cause a change in potential and thus an electric field between the materials. The electric field will push electrons back to the wide band element’s conduction band. The diffusion process continues until electron diffusion and electron drift balance each other, creating a junction at equilibrium similar to a p–n junction. Note that the undoped narrow band gap material now has excess majority charge carriers. The fact that the charge carriers are majority carriers yields high switching speeds, and the fact that the low band gap semiconductor is undoped means that there are no donor atoms to cause scattering and thus yields high mobility.

In the case of GaAs HEMTs, they make use of high mobility electrons generated using the heterojunction of a highly doped wide-bandgap n-type donor-supply layer (AlGaAs in our example) and a non-doped narrow-bandgap channel layer with no dopant impurities (GaAs in this case). The electrons generated in the thin n-type AlGaAs layer drop completely into the GaAs layer to form a depleted AlGaAs layer, because the heterojunction created by different band-gap materials forms a quantum well (a steep canyon) in the conduction band on the GaAs side where the electrons can move quickly without colliding with any impurities because the GaAs layer is undoped, and from which they cannot escape. The effect of this is the creation of a very thin layer of highly mobile conducting electrons with very high concentration, giving the channel very low resistivity (or to put it another way, "high electron mobility").

Electrostatic mechanism
Since GaAs has higher electron affinity, free electrons in the AlGaAs layer are transferred to the undoped GaAs layer where they form a two dimensional high mobility electron gas within 100 ångström (10 nm) of the interface. The n-type AlGaAs layer of the HEMT is depleted completely through two depletion mechanisms:
 * Trapping of free electrons by surface states causes the surface depletion.
 * Transfer of electrons into the undoped GaAs layer brings about the interface depletion.

The Fermi level of the gate metal is matched to the pinning point, which is 1.2 eV below the conduction band. With the reduced AlGaAs layer thickness, the electrons supplied by donors in the AlGaAs layer are insufficient to pin the layer. As a result, band bending is moving upward and the two-dimensional electrons gas does not appear. When a positive voltage greater than the threshold voltage is applied to the gate, electrons accumulate at the interface and form a two-dimensional electron gas.

Modulation doping in HEMTs
An important aspect of HEMTs is that the band discontinuities across the conduction and valence bands can be modified separately. This allows the type of carriers in and out of the device to be controlled. As HEMTs require electrons to be the main carriers, a graded doping can be applied in one of the materials, thus making the conduction band discontinuity smaller and keeping the valence band discontinuity the same. This diffusion of carriers leads to the accumulation of electrons along the boundary of the two regions inside the narrow band gap material. The accumulation of electrons leads to a very high current in these devices. The term "modulation doping" refers to the fact that the dopants are spatially in a different region from the current carrying electrons. This technique was invented by Horst Störmer at Bell Labs.

Manufacture
MODFETs can be manufactured by epitaxial growth of a strained SiGe layer. In the strained layer, the germanium content increases linearly to around 40-50%. This concentration of germanium allows the formation of a quantum well structure with a high conduction band offset and a high density of very mobile charge carriers. The end result is a FET with ultra-high switching speeds and low noise. InGaAs/AlGaAs, AlGaN/InGaN, and other compounds are also used in place of SiGe. InP and GaN are starting to replace SiGe as the base material in MODFETs because of their better noise and power ratios.

By growth technology: pHEMT and mHEMT
Ideally, the two different materials used for a heterojunction would have the same lattice constant (spacing between the atoms). In practice, the lattice constants are typically slightly different (e.g. AlGaAs on GaAs), resulting in crystal defects. As an analogy, imagine pushing together two plastic combs with a slightly different spacing. At regular intervals, you'll see two teeth clump together. In semiconductors, these discontinuities form deep-level traps and greatly reduce device performance.

A HEMT where this rule is violated is called a pHEMT or pseudomorphic HEMT. This is achieved by using an extremely thin layer of one of the materials – so thin that the crystal lattice simply stretches to fit the other material. This technique allows the construction of transistors with larger bandgap differences than otherwise possible, giving them better performance.

Another way to use materials of different lattice constants is to place a buffer layer between them. This is done in the mHEMT or metamorphic HEMT, an advancement of the pHEMT. The buffer layer is made of AlInAs, with the indium concentration graded so that it can match the lattice constant of both the GaAs substrate and the GaInAs channel. This brings the advantage that practically any Indium concentration in the channel can be realized, so the devices can be optimized for different applications (low indium concentration provides low noise; high indium concentration gives high gain).

By electrical behaviour: eHEMT and dHEMT
HEMTs made of semiconductor hetero-interfaces lacking interfacial net polarization charge, such as AlGaAs/GaAs, require positive gate voltage or appropriate donor-doping in the AlGaAs barrier to attract the electrons towards the gate, which forms the 2D electron gas and enables conduction of electron currents. This behaviour is similar to that of commonly used field-effect transistors in the enhancement mode, and such a device is called enhancement HEMT, or eHEMT.

When a HEMT is built from AlGaN/GaN, higher power density and breakdown voltage can be achieved. Nitrides also have different crystal structure with lower symmetry, namely the wurtzite one, which has built-in electrical polarisation. Since this polarization differs between the GaN channel layer and AlGaN barrier layer, a sheet of uncompensated charge in the order of 0.01-0.03 C/m$$^2$$ is formed. Due to the crystal orientation typically used for epitaxial growth ("gallium-faced") and the device geometry favorable for fabrication (gate on top), this charge sheet is positive, causing the 2D electron gas to be formed even if there is no doping. Such a transistor is normally on, and will turn off only if the gate is negatively biased - thus this kind of HEMT is known as depletion HEMT, or dHEMT. By sufficient doping of the barrier with acceptors (e.g. Mg), the built-in charge can be compensated to restore the more customary eHEMT operation, however high-density p-doping of nitrides is technologically challenging due to dopant diffusion into the channel.

Induced HEMT
In contrast to a modulation-doped HEMT, an induced high electron mobility transistor provides the flexibility to tune different electron densities with a top gate, since the charge carriers are "induced" to the 2DEG plane rather than created by dopants. The absence of a doped layer enhances the electron mobility significantly when compared to their modulation-doped counterparts. This level of cleanliness provides opportunities to perform research into the field of Quantum Billiard for quantum chaos studies, or applications in ultra stable and ultra sensitive electronic devices.

title: High-electron-mobility transistor


text:
Talk:High-electron-mobility transistor

Diagram
We need a diagram of a standard HEMT device and not just a PHEMT. Would someone be able to produce this? Mike 09:07, 21 May 2007 (UTC)

splitup of article Field effect transistor in progress, please see Talk:Field effect transistor Pjacobi 15:34, 19 Jul 2004 (UTC)
 * Done Pjacobi 21:29, 19 Jul 2004 (UTC)

The External Link in this article seems to be dead.
 * Gololo 21:27, 29 Nov 2006

History
Can anyone add a section on the history of the HEMT and in particular who lays claim to it - I believe it was a chap at Fujitsu. History of HEMT Transistors http://eesof.tm.agilent.com/docs/iccap2002/MDLGBOOK/7DEVICE_MODELING/3TRANSISTORS/0History/HEMTHistory.pdf Which says "Dr. Takashi Mimura, the inventor of HEMT, is currently a fellow of Fujitsu Laboratories."

But elsewhere there were scientists working on GaAs MODFETs and devices with various other names. I recall Linh Nuyen who founded Picogiga published papers on his TEGFET transistors when he was at Thomson CSF the French electronics company.

Linh Nuyen, the Company's Chairman and CEO, was the co-inventor of the High Electron Mobility Transistor ("HEMT").

http://compoundsemiconductor.net/cws/article/news/6174

http://www.freepatentsonline.com/EP1192665.html

IEEE Transactions on Electron Devices, vol. ED-29, No. 6, June 1982, D. Delagebeaudeuf and N. T. Linh, "Metal-(n) AlGaAs-GaAs two-dimensional electron gaz FET", pp. 955-960 describing the operation of a TEGFET and IEEE Transactions on Electron Devices, vol. 35, No. 7, July 1988, M. C. Foisy et al., "The role of inefficient charge modulation in limiting the current-gain cutoff frequency of the MODFET", pp. 871-878 describing the operation of a MODFET. http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=1&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=9&f=G&l=50&co1=AND&d=PTXT&s1=linh&s2=hemt&OS=linh+AND+hemt&RS=linh+AND+hemt

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1482310

Royzee (talk) 15:35, 29 February 2008 (UTC)

(Nuyen Trong Linh (talk) 22:13, 13 December 2008 (UTC))

Who is the inventor of the so-called HEMT

Thank you, Royzsee for having recalled my name. I am NUYEN TRONG LINH, mostly known in the scientific communitty as Dr Linh since I usually wrote my name Nuyen T. Linh.

I claim to be with my colleague Daniel DELAGEBEAUDEUF the inventors of the so-called HEMT : we filed for a patent of this device on the 28th of March 1979 in France (Patent n° 79 07803: "Transistor à effet de champ à fréquence de coupure élevée") and this patent has been approved on the 24th of October 1980 under the Patent n° FR2452791(A1) (please, try to access this information through the data base FR-esp@cenet. Note that the internal procedure at our company, Thomson-CSF took six months since we submitted our patent to the "Intellectual property Department" of the company in October 1978.

By that time I was Head of the Microwave Devices Department (Laboratoire de Composants Hyperfréquences) and Daniel Delagebeaudeuf is one of the senior scientists of my group. Our team at Thonson-CSF published our first paper on this device in the spring of 1980 in the magazine Electronics Letters, n°26, p.667(1980) with the title :"Two-dimensional gas MESFET structure". While our paper was under press, T. Mimura and his Fujitsu colleagues independently announced their High Electron Mobilty Transistor in the magazine Japanese Journal of Applied Phycics Letters, n°19, p.L 225 (1980). The Fujitsu team got the experimental data few weeks ahead of the Thomson-CSF's. But we were the first in the semiconductor world to get a propagation delay time below 20 picoseconds at room temperature, and to announce microwave performance.

Since this spring of 1980 to the end of 1985, the two teams Thonson-CSF and Fujitsu, fiercy but friendly competed. And more and more private or public laboratories join the "competition fiesta". The atmosphere was excellent since there was room for many of us from fundamental physics to practical applications.

Thirty years after the invention of this exceptional electronic device which strongly contributed to the success of the Iinformation Technology world, I am proud for having contributed into three basic matters :

 * 1) I predicted that the reduced dimensionality of the electron gas enhances the performance of the electronic device, that is why I called this device a two-dimensional electron gas field effect Transistor (TEGFET). This was the starting point of the man made crystal, the Nanotechnology in Electronics.

 * 2) I have promoted this technology for the microwave applications, instead of logic applications, with a clear view the present world in communications (which was the far future by that time) : satellite TV and cellular telephone... I clearly showed this future at all my talks during the early 1980's particularly the Plenary Lectures of the Divisions Semiconductor Physics of the German Physical Society hold in Freudenstadt March 1983 (Festkörper Probleme XXIII Advanced in Solid State Physics, published in Vieweg), whom I am indebted for the invitation.

 * 3) To accelerate the maturation of this technology, I took the incredible risk to found my own company and supplied the multilayers wafers to all companies who needed. How happy I was when the TV satellite dishes appeared in Japan during the Olympic games of 1988!

Now I am ready to contribute to any matters concerning the TEGFET or HEMT, not only technical matters. What about writing a book on this story which leads to three Nobel Prizes and some millionnaires (that is not the most important) and to a deep change of the world ?

(Nuyen Trong Linh (talk) 21:20, 13 December 2008 (UTC))

 * Your name has been misspelt in the patent and literature, which contributes the less attention you should deserve for this invention. Let the world know that your name is Nguyễn Trọng Linh and should not be misspelt. 220.228.146.11 (talk) 21:52, 12 August 2023 (UTC)

Proposed merge with MODFET
The first sentence of MODFET says that it is a synonym of HEMT ... the first sentence of this HEMT article says that it is a synonym of MODFET ... so it seems to me that the two articles ought to be merged. Do other people agree?

I'm not an expert in this area so I would have a hard time merging myself ... I'm hoping someone else volunteers ... :-) --Steve (talk) 20:30, 20 November 2012 (UTC)
 * Support as synonyms. Andy Dingley (talk) 22:44, 29 December 2015 (UTC)
 * Oppose until we have clearer argument and evidence that they are the same. ((re)Splitting is MUCH harder than merging) Talk:MODFET implies one may be subset of the other. Can we ask an expert who has contributed to both articles ? What is the history of the two terms ? Different developers ? Different structures ? Different materials ? - Rod57 (talk) 02:52, 2 January 2016 (UTC)
 * google of the two terms together find docs that all seem to treat them as synonyms. ( MODFET 40k, HEMT 483k => common name is HEMT ) - Rod57 (talk) 03:28, 2 January 2016 (UTC)

title: Talk:High-electron-mobility transistor


text:
Auxotrophy

Auxotrophy (αὐξάνω "to increase"; τροφή "nourishment") is the inability of an organism to synthesize a particular organic compound required for its growth (as defined by IUPAC). An auxotroph is an organism that displays this characteristic; auxotrophic is the corresponding adjective. Auxotrophy is the opposite of prototrophy, which is characterized by the ability to synthesize all the compounds needed for growth.

Prototrophic cells (also referred to as the 'wild type') are self-sufficient producers of all required metabolites (e.g. amino acids, lipids, cofactors), while auxotrophs require to be on medium with the metabolite that they cannot produce. For example saying a cell is methionine auxotrophic means that it would need to be on a medium containing methionine or else it would not be able to replicate. In this example this is because it is unable to produce its own methionine (methionine auxotroph). However, a prototroph or a methionine prototrophic cell would be able to function and replicate on a medium with or without methionine.

Replica plating is a technique that transfers colonies from one plate to another in the same spot as the last plate so the different media plates can be compared side by side. It is used to compare the growth of the same colonies on different plates of media to determine which environments the bacterial colony can or cannot grow in (this gives insight to possible auxotrophic characteristics. The method of replica plating implemented by Joshua Lederberg and Esther Lederberg included auxotrophs that were temperature-sensitive; that is, their ability to synthesize was temperature-dependent. (Auxotrophs are usually not temperature-dependent. They can also depend on other factors.) It is also possible that an organism is auxotrophic to more than just one organic compound that it requires for growth.

Genetics
In genetics, a strain is said to be auxotrophic if it carries a mutation that renders it unable to synthesize an essential compound. For example, a yeast mutant with an inactivated uracil synthesis pathway gene is a uracil auxotroph (e.g., if the yeast Orotidine 5'-phosphate decarboxylase gene is inactivated, the resultant strain is a uracil auxotroph). Such a strain is unable to synthesize uracil and will only be able to grow if uracil can be taken up from the environment. This is the opposite of a uracil prototroph, or in this case a wild-type strain, which can still grow in the absence of uracil. Auxotrophic genetic markers are often used in molecular genetics; they were famously used in Beadle and Tatum's Nobel prize-winning work on the one gene-one enzyme hypothesis, connecting mutations of genes to protein mutations. This then allows for biosynthetic or biochemical pathway mapping that can help determine which enzyme or enzymes are mutated and dysfunctional in the auxotrophic strains of bacteria being studied.

Researchers have used strains of E. coli auxotrophic for specific amino acids to introduce non-natural amino acid analogues into proteins. For instance cells auxotrophic for the amino acid phenylalanine can be grown in media supplemented with an analogue such as para-azido phenylalanine.

Many living things, including humans, are auxotrophic for large classes of compounds required for growth and must obtain these compounds through diet (see vitamin, essential nutrient, essential amino acid, essential fatty acid).

The complex pattern of evolution of vitamin auxotrophy across the eukaryotic tree of life is intimately connected with the interdependence between organisms.

The Mutagenicity test (or Ames test)
The Salmonella Mutagenesis test (Ames test) uses multiple strains of Salmonella typhimurium that are auxotrophic to histidine to test whether a given chemical can cause mutations by observing its auxotrophic property in response to an added chemical compound. The mutation a chemical substance or compound causes is measured by applying it to the bacteria on a plate containing histidine then moving the bacteria to a new plate without sufficient histidine for continual growth. If the substance does not mutate the genome of the bacteria from auxotrophic to histidine back to prototrophic to histidine, then the bacteria would not show growth on the new plate. So by comparing the ratio of the bacteria on the new plate to the old plate and the same ratio for the control group, it is possible to quantify how mutagenic a substance is, or rather, how likely it is to cause mutations in DNA. A chemical is considered positive for Ames test if it causes mutations increasing the observed reversion rate and negative if presents similar to the control group. There is a normal, but small, number of revertant colonies expected when an auxotrophic bacteria is plated on a media without the metabolite it needs because it could mutate back to prototrophy. The chances of this are low and therefore cause very small colonies to be formed. If a mutagenic substance is added, however, the number of revertants would be visibly higher than without the mutagenic substance. The Ames test, basically, is considered positive if a substance increases chance of mutation in the DNA of the bacteria enough to cause a quantifiable difference in the revertants of the mutagen plate and the control group plate. Negative Ames test means the possible mutagen DID not cause increase in revertants and positive Ames test signifies that the possible mutagen DID increase the chance of mutation. These mutagenic effects on bacteria are researched as a possible indicator of the same effects on larger organisms, like humans. It is suggested that if a mutation can arise in bacterial DNA under presence of a mutagen then the same effect would occur for larger organisms causing cancer. A negative Ames test result could suggest that the substance is not a mutagen and would not cause tumor formation in living organisms. However only few of the positive Ames Test resulting chemicals were considered insignificant when tested in larger organisms but the positive Ames test for bacteria still could not be conclusively linked to expression of cancer in larger organisms. While it can be a possible determinant of tumors for living organisms, humans, animals, and so on, more studies must be completed to come to a conclusion.

Auxotrophy-based methods to incorporate unnatural amino acids into proteins and proteomes
A large number of unnatural amino acids, which are similar to their canonical counterparts in shape, size and chemical properties, are introduced into the recombinant proteins by means of auxotrophic expression hosts. For example, methionine (Met) or tryptophan (Trp) auxotrophic Escherichia coli strains can be cultivated in a defined minimal medium. In this experimental setup it is possible to express recombinant proteins whose canonical Trp and Met residues are completely substituted with different medium-supplemented related analogs. This methodology leads to a new form of protein engineering, which is not performed by codon manipulation at the DNA level (e.g. oligonucleotide-directed mutagenesis), but by codon reassignments at the level of protein translation under efficient selective pressure. Therefore, the method is referred as selective pressure incorporation (SPI).

No organism studied so far encodes other amino acids than the canonical twenty; two additional canonical amino acids (selenocysteine, pyrrolysine) are inserted into proteins by recoding translation termination signals. This boundary can be crossed by adaptive laboratory evolution of metabolically stable auxotrophic microbial strains. For example, the first clearly successful attempt to evolve Escherichia coli that can survive solely on the unnatural amino acid thieno[3,2-b]pyrrolyl) alanine as the only substitute for tryptophan was made in 2015.

In popular culture
The 1993 film Jurassic Park (based on the 1990 Michael Crichton novel of the same name) features dinosaurs that were genetically altered so that they could not produce the amino acid lysine. This was known as the "lysine contingency" and was supposed to prevent the cloned dinosaurs from surviving outside the park, forcing them to be dependent on lysine supplements provided by the park's veterinary staff. In reality, no animals are capable of producing lysine (it is an essential amino acid).

title: Auxotrophy


text:
Talk:Artscroll transliteration

Your Artscroll transliteration of Shabbos contradicts the main article. Jayjg 15:35, 19 Jul 2004 (UTC)

 * I think they make some exceptions. --Ezra Wax 17:32, 19 Jul 2004 (UTC)
 * Absolutely, for "Shabbos". There may be others. I am not sure. They're not upfront about it, but they do have an internally consistent method of rendering these phonetics. I have redone the article. - CrazyRussian talk/email 00:35, 10 August 2006 (UTC)

Separate article
Does this really deserve its own page? I have proposed that it be merged back into ArtScroll. --Makaristos 20:02, 29 July 2007 (UTC)

title: Talk:Artscroll transliteration


text: Category:Le Sueur County, Minnesota

title: Category:Le Sueur County, Minnesota


text:
Frankie Trumbauer

Orie Frank Trumbauer (May 30, 1901 – June 11, 1956) was an American jazz saxophonist of the 1920s and 1930s. His main instrument was the C melody saxophone, a now-uncommon instrument between an alto and tenor saxophone in size and pitch. He also played alto saxophone, bassoon, clarinet and several other instruments.

He was a composer of sophisticated sax melodies, one of the major small group jazz bandleaders of the 1920s and 1930s. His landmark recording of "Singin' the Blues" with Bix Beiderbecke and Eddie Lang in 1927, was inducted into the Grammy Hall of Fame in 1977. His major recordings included "Krazy Kat", "Red Hot", "Plantation Moods", "Trumbology", "Tailspin", "Singin' the Blues", "Wringin' an' Twistin'", and "For No Reason at All in C" with Bix Beiderbecke and Eddie Lang, and the first hit recording of "Georgia On My Mind" in 1931.

"Tram" was described as one of the most influential and important jazz saxophonists of the 1920s and 1930s, particularly influencing the sound of Lester Young. He is also remembered for his musical collaborations with Bix Beiderbecke, a relationship that produced some of the finest and most innovative jazz records of the late 1920s. Trumbauer and Beiderbecke also collaborated with jazz guitarist Eddie Lang.

He was featured in the 2001 documentary Jazz by Ken Burns on PBS on the topic of the first jazz soloists and as an iconic image to symbolize jazz music.

Life and career
Born of part Cherokee ancestry in Carbondale, Illinois, United States, Trumbauer grew up in St Louis, Missouri, the son of a musical mother who directed saxophone and theater orchestras. His first important professional engagements were with the Edgar Benson and Ray Miller bands, shortly followed by the Mound City Blue Blowers, a local group that became nationally famous through their recordings on Brunswick.

Trumbauer recruited Bix Beiderbecke for Jean Goldkette's Victor Recording Orchestra, of which he became musical director. After leaving Goldkette, he and Beiderbecke worked briefly in Adrian Rollini's short lived New Yorkers band, then joined Paul Whiteman in 1927. The same year, Trumbauer signed a contract with OKeh and released a 78 recording of "Singin' the Blues", featuring Beiderbecke on cornet and Eddie Lang on guitar. "Singin' the Blues" was a jazz classic originally recorded and released by the Original Dixieland Jazz Band in 1920. The Okeh recording became a hit. Fletcher Henderson and His Orchestra recorded it in 1931 in the Trumbauer-Beiderbecke version.

Trumbauer played with Whiteman for eight of the following nine years. He had a separate contract with OKeh from 1927 through 1930, he recorded some of the small group jazz recordings of the era, usually including Beiderbecke until the April 30, 1929, session. He recorded a handful of sides in 1931 for Brunswick. In 1932, he organized a band in Chicago and recorded for Columbia, but gave up the orchestra and returned to New York late in 1933. During 1934–1936, while again a member of Paul Whiteman's Orchestra, he also made a series of recordings for Brunswick and Victor, often including Jack Teagarden.

In 1936 he led The Three T's, featuring the Teagarden brothers; in 1938, he and Mannie Klein started a band which they co-led; he billed himself as "Frank Trombar." In 1939, Trumbauer, a skilled pilot, left music (after recording a series of records for Varsity) to join the Civil Aeronautics Authority.

During World War II he was a test pilot with North American Aviation, and trained military crews in the operation of the B-25 Mitchell bomber. He continued to work for the CAA after the war, and also played in the NBC Orchestra. After 1947, although he continued to play and record, he earned most of his income in aviation.

Last years and death
Trumbauer died of a heart attack in Kansas City, Missouri, where he had made his home for some years. He was 55 years old.

Legacy
Lester Young acknowledged and cited Trumbauer as his main influence as a saxophonist. When an interviewer asked Young about his influences, he stated that Frankie Trumbauer was his major influence: "So, it's Trumbauer?" Young replied: "That was my man."

His life and career were documented in the biography Tram: The Frank Trumbauer Story by Philip R. Evans and Larry F. Kiner with William Trumbauer (Institute of Jazz Studies, Rutgers and Scarecrow Press Inc., 1994).

He was featured in Episode 3, "Our Language", in the 2001 documentary Jazz by Ken Burns on PBS on the topic of pioneering jazz soloists. A photograph of him holding his Holton C-melody saxophone was one of the images chosen by Burns to symbolize jazz. The photo is featured on all the intros and outros as well as in Episode 3, "Our Language". His 1927 solo in "Singin' the Blues" is analyzed as well.

He was known for double tonguing.

Honors
"Singin' the Blues", released by Frankie Trumbauer and His Orchestra featuring Bix Beiderbecke on cornet and Eddie Lang on guitar in 1927 as Okeh 40772-B, was inducted into the Grammy Hall of Fame in 1977. Frankie Trumbauer played the C-melody saxophone solos on the landmark jazz recording.

In 2005, his 1927 recording of "Singin' the Blues" with Bix Beiderbecke and Eddie Lang was placed on the U.S. Library of Congress National Recording Registry.

In 2008, his recordings of "Ostrich Walk" and "There'll Come a Time" with Bix Beiderbecke were included on the soundtrack to the Brad Pitt movie The Curious Case of Benjamin Button, which was nominated for 13 Academy Awards, based on the F. Scott Fitzgerald short story from Tales of the Jazz Age.

Ken Burns used a photograph of him in the 2001 documentary Jazz, on PBS, on the topic of pioneering jazz soloists and as an image to represent jazz music.

Compositions
Trumbauer's compositions include:
 * "Trumbology" (1927)
 * "Plantation Moods" with David Rose
 * "Red Hot", "Wringin' an' Twistin'" with Fats Waller
 * "Barbed Wire Blues"
 * "Troubled"
 * "I Like That"
 * "Bass Drum Dan"
 * "Break it Down"
 * "I'm Glad"
 * "Choo Choo"
 * "Sun Spots"
 * "Eclipse"
 * "Meteor"
 * "Krazy Kat" with Chauncey Morehouse
 * "G Blues"
 * "Tailspin" with Jimmy Dorsey
 * "Crying All Day"
 * "Loved One"
 * "Apple Blossoms" with Joe Venuti, Lennie Hayton, and Eddie Lang
 * "Three Blind Mice" with Chauncey Morehouse
 * "The Mayor of Alabam'"
 * "Flight of a Haybag"
 * "Cinderella's Wedding Day"
 * "Runnin' Ragged"
 * "For No Reason at All in C" with Bix Beiderbecke (1927), which was released as a single 78 on Okeh and subsequently reissued on Columbia and Parlophone.

Major recordings

 * "I'm Glad"/"Flock O' Blues," Sioux City Six featuring Bix Beiderbecke and Miff Mole, recorded October 11, 1924, New York, released as Gennett 5569
 * "Clarinet Marmalade"/"Singin' the Blues," recorded on February 4, 1927, in New York and released as Okeh 40772
 * "Riverboat Shuffle"/"Ostrich Walk," recorded May 9, 1927, New York, Okeh 40822
 * "I'm Coming, Virginia"/"Way Down Yonder in New Orleans", recorded on May 13, 1927, in New York and released as Okeh 40843
 * "For No Reason at All in C"/"Trumbology," recorded on May 13, 1927, in New York and released as Okeh 40871, Columbia 35667, and Parlophone R 3419
 * "Wringin' an' Twistin'," recorded on September 9, 1927, in New York and released as Okeh 40916 and Vocalion 3150
 * "Krazy Kat" recorded September 28, 1927, New York Okeh 40903
 * "Baltimore" b/w "Humpty Dumpty," recorded September 28, 1927, New York, Okeh 40926
 * "Mississippi Mud" (vocal by Bing Crosby)/"There'll Come a Time (Wait and See)," January 9, 1928, New York, Okeh 40979
 * "Ol' Man River" (From "Show Boat") recorded with Paul Whiteman and His Orchestra on January 11, 1928 in New York and released as Victor 21218-A and Victor 25249 with Bing Crosby on vocals and Bix Beiderbecke on cornet. No. 1 for 1 week
 * "Borneo"/"My Pet," recorded on April 10, 1928, in New York and released as Okeh 41039
 * "Georgia On My Mind," recorded September 24, 1931, Chicago, Illinois, Brunswick 6159
 * "Troubled"/"Plantation Moods," recorded November 20, 1934, New York, Victor 24834, HMV B.D. 158 in the UK

title: Frankie Trumbauer


text:
Talk:Magnetic resonance imaging

How to cover multiparametric MRI
Multiparametric MRI (mpMRI) seems widely used to diagnose/characterise prostate cancer, and is being used experimentally for diagnosing clear-cell renal cancer. Is there a standard mpMRI or a variety ? - Rod57 (talk) 18:10, 12 January 2018 (UTC)
 * I've now introduced this term in the intro of MRI sequence. Its broadest sense would include any sequence combination. Thus, every included sequence in the particular study should be mentioned when describing for example sensitivity and specificity of the method. Mikael Häggström (talk) 09:31, 13 January 2018 (UTC)

MRI Inventor
I am not sure why the discussion on MRI does not mention anything about its inventor Dr. Raymond Damadian.
 * If you have well-sourced info that Raymond Damadian invented the MRI (or a specific type or something), add it to the article. Note: it's recommended to sign your talk posts with four tildes ("~"). IAmNitpicking (talk) 14:11, 12 July 2021 (UTC)

 * D'accord, please sign your post (WP:SIG). According to Lancet: "Damadian, who had become well known for his attempts to seek credit for the technology, demanded that he share the Nobel Prize; Lauterbur refused to discuss Damadian then, and even as early as 1992, when Kevles interviewed him for her book." If this helps the discussion. 17387349L8764 (talk) 18:50, 30 November 2021 (UTC)

 * Do you think the initiator of this thread was Damadian himself? IAmNitpicking (talk) 19:37, 1 December 2021 (UTC)
 * MRI is a contribution of various scientist and mathematics. So, crediting one particular scientist for it seems to be somewhat odd. دَستخَط، اِفلاق  (کَتھ باتھ) 08:33, 9 March 2022 (UTC)
 * Not crediting Raymond at all seems extremely odd 2603:6011:9600:52C0:FC2A:8A28:F293:758 (talk) 15:34, 3 March 2023 (UTC)

"MRI may still be seen as a better choice than a CT scan"
"While the hazards of ionizing radiation are now well controlled in most medical contexts, an MRI may still be seen as a better choice than a CT scan."

That is a very reductionist view and depends very much on the setting. The way it is written here (in the introduction, possibly read by thousands of patients before getting medical imaging) it conveys a general superiority of MRI over CT, which does not hold true. It's like saying "While the hazards of a sharp blade are well controlled in most food-related contexts, a spoon may still be seen as a better choice than a knife." MRI is simply another tool with a different set of appropriate application scenarios. ~A Radiologist

 * Agreed - it is also unsourced and I have removed it. CV9933 (talk) 09:33, 8 August 2021 (UTC)

Two history sections?
It would be better if either section was removed or both combined. Especially since the first section is too short. 2001:8003:B027:ED00:C53C:BFB0:A078:1BE0 (talk) 01:09, 12 February 2022 (UTC)
 * Yes the history of mri is sufficient enough to have it's own article so we don't need two history sections here. CV9933 (talk) 19:31, 17 February 2022 (UTC)

Mechanism paragraph confusing
In the section on mechanism, it says:
 * To perform a study, the person is positioned within an MRI scanner that forms a strong magnetic field around the area to be imaged. First, energy from an oscillating magnetic field is temporarily applied to the patient at the appropriate resonance frequency. Scanning with X and Y gradient coils causes a selected region of the patient to experience the exact magnetic field required for the energy to be absorbed. The atoms are excited by a RF pulse and the resultant signal is measured by a receiving coil.

Is the part "First, energy from an oscillating magnetic is applied" referring to "a RF pulse" mentioned later, or are they separate? This should be made clearer. Also, this paragraph doesn't make clear the importance of relaxation times. Further, it's unclear what X and Y are referring to here. AxelBoldt (talk) 18:54, 18 February 2024 (UTC)

title: Talk:Magnetic resonance imaging


text:
Bahuvrihi

A bahuvrihi compound (from बहुव्रीहि, originally referring to fertile land but later denoting the quality of being wealthy or rich) is a type of compound word that denotes a referent by specifying a certain characteristic or quality the referent possesses. A bahuvrihi is exocentric, so that the compound is not a hyponym of its head. For instance, a sabretooth (smil-odon) is neither a sabre nor a tooth, but a feline with sabre-like teeth.

In Sanskrit bahuvrihis, the last constituent is a noun—more strictly, a nominal stem—while the whole compound is an adjective. In Vedic Sanskrit the accent is regularly on the first member (tatpurusha rāja-pútra "a king's son", but bahuvrihi rājá-putra "having kings as sons" (lit. king-sons), viz. rājá-putra-, m., "father of kings", rājá-putrā-, f., "mother of kings"), with the exception of a number of non-nominal prefixes such as the privative a; the word bahuvrīhí is itself likewise an exception to this rule.

Bahuvrihi compounds are called possessive compounds in English. In English, bahuvrihis can be identified and the last constituent is usually a noun, while the whole compound is a noun or an adjective. The accent is on the first constituent. English bahuvrihis often describe people using synecdoche: flatfoot, half-wit, highbrow, lowlife, redhead, tenderfoot, long-legs, and white-collar.

In dictionaries and other reference works, the abbreviation 'Bhvr.' is sometimes used to indicate bahuvrihi compounds.

English

 * "Houndstooth", a woven fabric with a patterns resembling dog's teeth: "She's wearing houndstooth."
 * "Old money", members from established upper-class who have usually inherited their wealth: "He's definitely old money."
 * "Bluestocking", an educated, intellectual, or artistically accomplished woman: "Auntie Maud will never marry; she's a bluestocking."
 * White-collar and blue-collar labor, referring to common colors of uniforms of clerks and workmen respectively c. early 20th century.

Other languages

 * Skinfaxi and Hrímfaxi (meaning shining-mane and rime-mane; two horses in Norse mythology) are two examples of Old Norse bahuvrihis.
 * Haxāmaniš

title: Bahuvrihi


text: Talk:Hawaiian architecture

title: Talk:Hawaiian architecture


text:
Aphanes

Aphanes (parsley-piert) is a genus of around 20 species in the rose family (Rosaceae), native to Europe, Asia and Australia. A 2003 study indicated that Aphanes may belong to the genus Alchemilla, commonly called lady's-mantle. They are slender, annual prostrate herbs, much-branched with deeply lobed leaves, pilose (covered with soft hair) and on short petioles. The tiny green to yellow flowers without petals grow in clusters in the denticulate leaflike stipules.

Species include:
 * Aphanes andicola Rothm.
 * Aphanes arvensis L. – field parsley-piert, western lady's-mantle, parsley breakstone
 * Aphanes australiana – Australian piert
 * Aphanes cotopaxiensis Romoleroux & Frost-Olsen
 * Aphanes cuneifolia (Nutt.) Rydb.
 * Aphanes looseri Rothm.
 * Aphanes microcarpa (Boiss. & Reut.) Rothm. (syn. A. australis, A. inexpectata) – slender parsley-piert
 * Aphanes occidentalis (Nutt.) Rydb. – dew cup, lady's mantle

title: Aphanes


text:
File talk:Si romap.png

Italia
What is a term "Italia" doing on this map? When did this term actually originate? Dalmatia is also much too north, I guess, at least one Gulf of Kvarner. --XJamRastafire 15:52, 19 Jul 2004 (UTC)

 * As far as I know, the first known appearance of the term "Italia" dates from the 5th century BC. In that period, this name only referred to the southern part of the Italian Peninsula. In the 1st century AD "Italia" referred to the land from the Strait of Messina to the Alps and its border is shown in the map.
 * As regards the province of Dalmatia, its northern border touched the Kupa/Kolpa river. Dalmatia encompassed Kvarner and a part of Istria too. Boraczek 08:02, 21 Jul 2004 (UTC)

BTW: recent scholarship suggests that Emona was a part of Italia not of Pannonia. Could you redraw your map? --213.157.228.253 16:54, 4 August 2006 (UTC)

title: File talk:Si romap.png


text:
Talk:JFET

Spanish Version
There is a real mismatch with spanish version. There, you can read $$I_D = \frac{k}{2}V_{DS}(V_{GS} - V_p)$$ instead of $$I_D = (2a) \frac{W}{L} q N_d {{\mu}_n} \left[1 - \sqrt{\frac{V_{GS}}{V_P}}\right]V_{DS}$$ for the current in the linear region.

Does anybody know which is the correct expression?. —Preceding unsigned comment added by Aasdelat (talk • contribs) 15:19, 6 August 2008 (UTC)

German version
$$I_{DS} = I_{DSS}\left[1 + \frac{V_{GS}}{V_P}\right]^2 $$?????? Is this right??? in the german wikipedia you can read        $$I_{DS} = I_{DSS}\left[1 - \frac{V_{GS}}{V_P}\right]^2$$ minus in placace of plus  —Preceding unsigned comment added by 89.49.121.34 (talk) 11:06, 6 March 2008 (UTC)

 * It depends on the sign you consider for $$V_{GS}$$. For example: in a n-channel JFET, the gate is usually at a potential that is less than source's one. Source is connectet to ground, so its potential is zero, and $$V_{GS} < 0$$. So, if you retain the sign of $$V_{GS}$$, you use $$I_{DS} = I_{DSS}\left[1 + \frac{V_{GS}}{V_P}\right]^2$$. But if you don't want to manage the sign of $$V_{GS}$$, you use $$I_{DS} = I_{DSS}\left[1 - \frac{V_{GS}}{V_P}\right]^2$$.
 * Also, if JFET is p-channel, the gate potential must be bigger than Source's. So, $$V_{GS}>0$$ and you must use the formula with the plus sign. —Preceding unsigned comment added by 212.225.187.144 (talk) 09:28, 14 August 2008 (UTC)

Comparison with other transistors
This section should describe in concrete terms why a JFET would be used and not a MOSFET. We see some functional differences but not generalization. Give me funtions. ~ -- — Preceding unsigned comment added by 206.188.55.225 (talk • contribs) 5 apr 2008 23:55

Split
splitup of article Field effect transistor in progress, please see Talk:Field effect transistor Pjacobi 15:52, 19 Jul 2004 (UTC)
 * Done Pjacobi 21:28, 19 Jul 2004 (UTC)

Too technical
The language in this article is probably too technical for most Wikipedians. It needs a good copyedit. I've just linked everything I could; some technical terms are still unlinked. - dcljr 18:41, 16 Sep 2004 (UTC)
 * In particular, VP in the equations needs to be defined. 71.41.210.146 12:04, 30 October 2007 (UTC)

Merge - Uses of JFETs
It has been suggested that Uses of jfet be merged into this article or section.

User:Ywywyw (Contributions) did not say why they put it in a separate article.

User:Yume no Kishi proposed that it be merged into JFET

Support It should just be a heading. --RobBrisbane 11:01, 8 July 2007 (UTC)

merge it!!XU-engineer 18:25, 29 July 2007 (UTC)

I don't even think it's worth attempting to merge; it appears to have been created by cutting phrases from descriptions of specific circuits and pasting them together without context. Maybe it was even created by a bot? Delete. --Theodore Kloba 12:17, 20 October 2007 (UTC)

 * Not to mention that at least some of the material is subject to copyright issues. I've deleted the page and replaced it with a redirect instead. --Michael Snow 20:22, 9 November 2007 (UTC)

This is an example of an article that has been cut to pieces by the wiki police until it is valueless. Typically they are very arrogant young men who don't know much about the subject they are editing. What serious expert would contribute to wiki when their efforts are just going to be deleted by some oaf. Well the answer it turns out is none. Hence this pointlessness. — Preceding unsigned comment added by 113.190.186.64 (talk) 22:59, 18 July 2011 (UTC)

Error?
I have a textbook in front of me that says current in n-type JFETs flows from drain to source. —Preceding unsigned comment added by 199.106.52.17 (talk) 16:18, 30 October 2007 (UTC)

 * That's definitely true of power MOSFETs. In an N-channel current flows from drain to source (electrons flow from source to drain), In a P-channel current flows from source to drain (electrons flow from drain to source). The reason for this is relatively obvious if you consider that in both cases the source is connected to the bulk, yet they have the N and P doped silicon reversed. I don't see any reason why JFETs would be any different. I believe that signal MOSFETs inside ICs (and possibly some monolothic FETs, although I am not sure) do not have the source connect to the bulk, so current flow can be bidirectional. Therefore, it's a bit hard to generalise. But I think the fault in the article is that it is not very specific. The statement made is true, for one common type of JFET (P-channel), but not the other major type. N-channel is probably more common, in fact. Last time I bought JFETs I don't even remember the store offering P-channels. I would qualify the statement. —Preceding unsigned comment added by 220.233.81.49 (talk) 17:26, 4 January 2008 (UTC)

The response immediately above is almost hopelessly muddled. An n-channel device, whether JFET or MOSFET, indeed supports current flow from drain to source, in both triode and saturation regions of operation. It also supports current flow in the opposite direction, but in triode only — Preceding unsigned comment added by 2602:30A:2E8A:CBA0:A81D:8365:FC62:C90F (talk) 10:16, 11 May 2016 (UTC)

Disjointed style
The first paragraph of the "comparison with other transistors" is bizarrely structured. It says (paraphrased) "x is small. y is extremely small. x is much smaller than z".

Wouldn't it be clearer to say "JFET have much smaller gate currents than BJT, making higher input impedances possible. MOSFET have even smaller gate currents but JFETs have higher transconductance (explain why this is desirable)." —Preceding unsigned comment added by 213.41.173.68 (talk) 22:23, 17 November 2007 (UTC)

Well this is'nt completely true that in N channel the current flows from drain to source, it is only true in the junction of drain and source.... —Preceding unsigned comment added by 221.135.57.130 (talk) 04:16, 4 December 2009 (UTC)

Unclear
The article mentions negative VGS. While this may be perfectly clear to EE, it is not stated whether VAB means potential of A minus potential of B or the reverse.

People who are learning this stuff will benefit from an explanatory sentence like "i.e. the gate is at a lower/higher potential than the source". —Preceding unsigned comment added by 213.41.173.68 (talk) 22:30, 17 November 2007 (UTC)

 * The convention is A-B throughout electronics. Cannot really go explaining that on every electronics article.   Sp in ni  ng  Spark  19:42, 14 June 2008 (UTC)
 * Funny you should say that.
 * Considering how the graph for the jfet characteristics gets is wrong. (OTherwise I agree).
 * I've also learned that VGS means voltage from gate to source. But in that case, for an n-channel jfet, the transfer charact. graph axis should point to the right; or if points toward left, it should be either VSG or -VGS. Hoemaco (talk) 13:31, 11 January 2024 (UTC)

Mathematical model
On the 'Mathematical model' part it's not clear what Id, Ids and Idss are.--CaioMarcos (talk) 04:48, 14 July 2008 (UTC)

Function
Besides comparing the JFET with a garden hose this section explains nothing at all. I'm not into this myself currently, but explaining (physically) what happens when gate voltage changes would be the least imho. --87.185.10.163 (talk) 20:44, 13 December 2007 (UTC)

 * A picture of the junctions in different states would be nice? I also think a picture of just the physical layout of various types of FETs would be useful.  This information is typically available at simiconductor manufacturer's websites.

 * I guess I'll try to make some.

JWhiteheadcc (talk) 09:02, 2 April 2008 (UTC)

Translation into Chinese Wikipedia
The sections "Schematic symbols" and "Comparison with other transistors" of the 13:32, 13 January 2009 BorgQueen version of this article are translated in to Chinese Wikipedia--Wing (talk) 15:10, 6 February 2009 (UTC)

ads — Preceding unsigned comment added by 115.252.45.251 (talk) 04:51, 20 June 2011 (UTC)

Advertising
The phrase "for the Temic J201 device" seems overtly advert-like. Perhaps this could be changed to something a bit more generic? — Preceding unsigned comment added by 173.74.164.193 (talk) 03:55, 14 October 2011 (UTC)

Figure
I think there is an error in the figure. The right side x axis label says Vds. Shouldn't this be Vgs? blackcloak (talk) 22:31, 9 November 2011 (UTC)

 * Answering in hope others have the same idea (I know from exams I correct).
 * Nope. In that case you would have two graphs, with the same axes, but different graph, that's no possible.
 * But the left graph should say -VGS actually. Hoemaco (talk) 13:34, 11 January 2024 (UTC)

Let's expand the abbreviation in the title
I know that many people (especially technically apt) use only the term "JFET". But for the average Wikipedia reader the full name is more understandable. Abbreviated references to the article will then display the full name of the device (as a tool-tip and/or in the status-bar) when hovered, like here for example: FET

I believe spelling out the title would be closer to the Manual of Style and the  title format recommendations. These recommend only abbreviations like LASER (Light Amplification by Stimulated Emission of Radiation) to stay abbreviated even in the page title. After the move double redirects must be cleaned up, of course. But there are even some bots to do that job.

What do you think? Zeptomoon chat/chase 11:16, 14 October 2012 (UTC)

 * Well, In my experience, JFET is very similar to laser. When you study microelectronics, it's presented to you about once what the letters stand for and after that its not mentioned again. You just call it a JFET (or Laser). --71.38.170.27 (talk) 05:22, 14 November 2012 (UTC)

VGS definition
I'm a little confused by this type of wording and the variables:

 * "To switch off an n-channel device requires a negative gate-source voltage (VGS)."

I would think that the "gate-source voltage" would be the voltage from the source to the gate. But yet, the symbolic representation of a n-channel device shows an arrow pointing into the gate, which to me, implies the gate is higher voltage than the source, and that VGS would be positive. Do I just have the notation wrong? If VGS represented how many volts the source was higher than the gate this would make sense, but that would violate my intuition for what VGS should represent. Thanks. -Theanphibian (talk • contribs) 15:50, 19 December 2012 (UTC)

 * The arrow indicates the polarity of the P-N diode junction between the gate and channel, so it points in for an N-Channel device to indicate that if the gate voltage is more positive than the channel, current will flow into the gate. (And current will increase above the saturation current). --Theodore Kloba (talk) 15:50, 13 March 2015 (UTC)
 * When you say VGS it means G->S voltage, or if using potential differences: VGS=VG-VS.
 * As far as I know this kind of notation is universally accepted. Hoemaco (talk) 13:35, 11 January 2024 (UTC)

Mathematic model fracked
In this 2008 edit, the craziness started by relabeling the small-voltage IDS as IDSS, which later got called a saturation current, since that's what that wrong name would usually mean. The model is all wrong. If we had a source we could go back and look and fix it. Maybe someone with a source handy will try to make it right. Dicklyon (talk) 02:11, 9 February 2014 (UTC)

I have corrected, sourced, and explained parts of it. If anyone has good books handy, some checking and help would be useful. Dicklyon (talk) 09:31, 9 February 2014 (UTC)

Silicon Carbide JFETs
A section is needed for the relatively new SiC JFETs. Anybody? --Theodore Kloba (talk) 15:50, 13 March 2015 (UTC)

Comments on the article
1. Is the image on the top right showing the flow of conventional current or electron current? The text says that electric charge flows from source to drain so my understanding is that conventional current flows from drain to source. If that is the case, then the image shows the electron current. Please confirm since this is confusing.

2. "Officially, the style of the symbol should show the component inside a circle (representing the envelope of a discrete device)."

Since this is the case, then the symbols be replaced by equivalents with circles.

3. "In 1947, researchers John Bardeen, Walter Houser Brattain, and William Shockley failed in their repeated attempts to make a FET."

Is that a fair statement? The folks above invented the MOSFET!

4. Was the JFET invented before the MOSFET? If it was, the history should mention something about it.

5. It would be nice to add notes about how much of the market JFETs have in comparison to MOSFETs. I spoke to a university professor that told me JFETs are slowly being removed from university books. I get the feeling the JFETs will slowly disappear or they will take a very small piece of the market. I also see that the comment above mine talks about SiC JFETs. Is this a resurgence in the use of JFETs?

ICE77 (talk) 18:15, 24 July 2015 (UTC)

 * Let me answer some of these
 * 1. Since it shows a p-channel JFET, it is apparently showing electrons or other negative charge carriers entering the source.
 * 2. The text explains how the circle style has become historic, for all transistor types except where a can-style metal housing is used as a separately grounded Faraday cage/screen.
 * 3. In 1947 they failed to build a FET, but succeeded in inventing the BJT, which was the first usable transistor (but not a FET at all), they later went on to other victories, including in development of FETs. The sentence in the article is about how hard it was to turn the 1920s invention into a real device.
 * 4. YES, the JFET is the original (non-experimental) FET, all others are later improvements.
 * 5. Many lesser universities are deleting all sorts of fundamental knowledge from textbooks, making them unworthy of calling themselves universities (I have seen that in my own field too). JFETs are (besides being the original and simplest FET) useful for a number of analog circuits (the uses section of this article needs expansion) where switching MOSFETs (and especially the enhancement MOSFETs) tend to fail miserably due to parameters having the wrong sign or being orders of magnitude wrong for the task.  Now a different issue is that JFETs like many other semiconductors are increasingly made only as parts of larger microchips which makes them less available as discrete (standalone) components for device engineers and lab exercises, but this doesn't remove the need for electronics engineers to understand them conceptually when they appear as part of the (actual or equivalent) diagram explaining the function of a microchip.
 * Jbohmdk (talk) 01:38, 2 January 2016 (UTC)
 * 4. YES, the JFET is the original (non-experimental) FET, all others are later improvements.
 * 5. Many lesser universities are deleting all sorts of fundamental knowledge from textbooks, making them unworthy of calling themselves universities (I have seen that in my own field too). JFETs are (besides being the original and simplest FET) useful for a number of analog circuits (the uses section of this article needs expansion) where switching MOSFETs (and especially the enhancement MOSFETs) tend to fail miserably due to parameters having the wrong sign or being orders of magnitude wrong for the task.  Now a different issue is that JFETs like many other semiconductors are increasingly made only as parts of larger microchips which makes them less available as discrete (standalone) components for device engineers and lab exercises, but this doesn't remove the need for electronics engineers to understand them conceptually when they appear as part of the (actual or equivalent) diagram explaining the function of a microchip.
 * Jbohmdk (talk) 01:38, 2 January 2016 (UTC)
 * Jbohmdk (talk) 01:38, 2 January 2016 (UTC)

Meaning of higher voltage at the end of the introduction
Towards the end of the introduction part, its written that in a n channel jfet, the voltage applied at the gate is lower than that applied at the source, and vice-versa for p channel. Lower voltage applied implies lower potential right? (So that GS junction can be reverse biased). So could I change it to say that as that is more simpler to understand.. Mr.Mog (talk) 05:30, 2 March 2019 (UTC)
 * Yes, pretty much so. The lead image caption is also needing work; it says "Electric current from source to drain in a p-channel JFET is restricted when a voltage is applied to the gate."  But "when a voltage is applied" is meaningless.  Should say perhaps "when a voltage that reverse biases the gate junction is applied".  Also note that it's actually possible, though not typical, to have an "enhancement mode" JFET, which is "off" at zero bias and turns on with forward bias (up to about 0.5 V). Dicklyon (talk) 07:04, 2 March 2019 (UTC)

Pinch-off voltage
No wonder I've always been confused about this. I've found references that define the terms to mean completely different things:

 * Threshold voltage:
 * value of vGS .. for which the channel is completely depleted .. vGS=VGS(OFF).
 * the gate-source voltage at which drain current approaches zero
 * Cutoff voltage
 * the gate-source voltage at which drain current approaches zero .. VGS(OFF)
 * VGS (off). It is the gate-source voltage where the channel is completely cut off and the drain current becomes zero.
 * VGS(off) is the value of VGS at which the drain current is 0.
 * https://www.researchgate.net/profile/Daniel_Montes3/publication/303945767/figure/fig21/AS:743982732673026@1554390714177/MOSFET-Behavior-Showing-Drain-Current-vs-Vds-with-Various-Vgs-in-Ohmic-and-Saturation_Q640.jpg VGS(off) is horizontal line at bottom
 * Pinch-off voltage definition 1:
 * value of vGS .. for which the channel is completely depleted .. vGS=VGS(OFF)
 * At this value of vGS the channel is completely depleted .. denoted VP
 * the gate-source voltage at which drain current approaches zero .. VP
 * Pinch-off voltage definition 2:
 * (VP). It is the minimum drain-source voltage at which the drain current essentially becomes constant.
 * This is a vertical line on the IDS vs VDS graph.
 * https://nanopdf.com/download/8-chapter-7_pdf shows this vertical Vp line, but also labels another line as "pinch off" for another VGS
 * https://www.electronics-tutorials.ws/wp-content/uploads/2018/05/transistor-tran18.gif shows VP as a vertical line on VDS axis, but also shows "Pinch-off Region" at the bottom
 * http://elektroarsenal.net/img/720/image841_0.jpg VDS(sat) is a curved line, defined in relation to VP which is a vertical line.
 * https://www.researchgate.net/profile/Daniel_Montes3/publication/303945767/figure/fig21/AS:743982732673026@1554390714177/MOSFET-Behavior-Showing-Drain-Current-vs-Vds-with-Various-Vgs-in-Ohmic-and-Saturation_Q640.jpg Vertical line Vp
 * Pinch-off voltage definition 3:
 * VP is the value of the VDS at which the drain current reaches a constant value for a given value of VGS.
 * "for a given VGS" means it follows the curve (and is better known as VDS(sat)?)
 * https://www.tina.com/resources/home/field-effect-transistor-amplifiers-2/3-large-signal-equivalent-circuit/#attachment_1916 has "pinchoff voltages" along a curved line

We should not be using the term "pinch-off voltage", then, except for definition 2 (unless there's an unambiguous alternative for that). — Omegatron (talk) 02:45, 4 January 2021 (UTC)

Datasheet nonsenses... by default from most makers.
Things like published in the wiki "For example, VGS(off) for the Temic J202 device varies from −0.8 V to −4 V.", the parameters are NOT tested, this is just a very generic guidance and the numbers have been copied directly from the 1976 datasheet and have no relation to current production line. Honestly. In many cases they have been carried over or copied from the competition without a grain of critical thinking.

There is also other evidence of these nonsenses and explained in a siliconix book on JFET transistors, that ALL the JFET parameters depend on each other, and one CAN NOT vary independently of each other, like the datasheets suggest. When you change the V(GS(off)), the resistance and current changes accordingly, and NOT independently, as the many datasheets suggest. When you look at the characteristic and min/max curves and compare those with the stated gfs Min (mS), and IDSS Min (mA), vs the V(GS(off)), you will see that the range of possible parameters is much narrower than the wide number guesstimates in the datasheet.

The other error comes from Fairchild transistor manufacture and sorting technology. Say, Process 92 transistors. It says the V(GS(off)) is between -0.8V and -4V, but that is for the whole Process 92 offer, and not for that one specific product! The margin of error in the datasheet is stated as exceedingly large, but that is for both historical reasons, and the current company not knowing what they are making, anyway. You can e-mail them and they don't know. I did that. The datasheets have pictures copied from 1970's that have no relation to the product, even, it is a jungle.

If you want guaranteed parameters and sorting, do for SANYO, now part of ON. (Motorola, Fairchild, Sanyo, and many others, feel free to add). To add to that. Vishay/Siliconix has killed their JFET line, which were far superior. When you buy the slassics 2Nxxx or Jxxx from ON, you have NO CLUE what the JFET is based on, is it the Fairchild, Siliconix, Motorola, or some place in the Czech Republic. Sanyo are better specified and sorted.

Refer to "2-7 CHARACTERISTIC INTERRELATIONSHIPS" page 50, DESIGNING WITH FIELD-EFFECT TRANSISTORS, SILICONIX INC., Editor in Chief, Arthur D. Evans, McGRAW-HILL BOOK COMPANY, and more

Usage
Hi, Could someone add a “Usage” or “Applications” section that concisely summarizes JFETs’ most common industrial usage and/or the most common commercial applications wherefor JFETs are used? For example, were JFETs ever used for digital logic, or did solid-state digital logic jump directly from primarily using BJTs directly to primarily using MOSFETs as the implementation technology? ’preciate it  —Arrandale Westmere (talk) 03:34, 22 October 2023 (UTC)

 * It's funny I've never heard of JFETs being used for digital logic. But I googled, and sure enough found there is at least one application for JFET SiC digital logic cause it can operate at over 500 degrees Celsius with radiation, apparently (https://www.techbriefs.com/component/content/article/tb/pub/briefs/semiconductors-and-ics/3415). Em3rgent0rdr (talk) 03:50, 22 October 2023 (UTC)

title: Talk:JFET


text:
Talk:Bermuda Agreement

Bermuda Agreement

Although of great signficance and a model for many ASAs that have followed, I seriously question whether Bermuda One was "the first bilateral Air Transport Agreement ..." I have seen reference to such a bilateral agreement concluded as early as August 1913 between France and Germany. I also understand that Spain and the USA concluded such a bilateral in 1944 very soon after the Chicago Conference.

Also the text on the Thai site that is linked to does not have a key part of the arrangements reached as part of Bermuda One, namely the capacity principles.

John Macilree 10:01, 10 December 2006 (UTC)

External links modified
Hello fellow Wikipedians,

I have just modified one external link on Bermuda Agreement. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20150518100049/http://archives.californiaaviation.org/airport/msg52856.html to http://archives.californiaaviation.org/airport/msg52856.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 13:48, 18 July 2017 (UTC)

title: Talk:Bermuda Agreement