text:
Talk:Thai lunar calendar

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The following was added anonymously into the article. As the article is my "child" I think that comment deserves preservation :-) andy

This is useful info - Srini / Khalai

Well for one thing, the Gregorian Year 2004 is 2548 in the Buddhist Era. Most cosmo thais follow the European calendar months, although there is a lunar calendar used for religious holidays. Long ago, when the Thais migrated from China, they brought their lunar system with them. However, since the agricultural (seasonal) cycles differed, the calendar was adjusted (and is different in different areas of Thailand and around SE Asia, for that matter).

The latter paragraph is incorrect. The lunar calendar came from India not from China, and is not just used for religious holidays. For all devout Buddhists it determines their weekly schedules (in particular, wan phra). The Thais did not migrate from China, they (or rather the Siamese, renamed Thais in 1942 by Field Marshal Phibul Songkhram for political reasons) migrated northwards from India (mainly via the Indianised states in the area of what is now Cambodia) and the Malay peninsula. The myth about the Siamese having come from China was propagated by Phibul Songkhram and his cohorts because of military ambitions to take over the Western colonies in the area as the Western powers retreated from them, especially those inhabited by peoples ethnically related to the Lao, such as Laos, Tonkin in Vietnam, parts of Cambodia, numerous provinces of southern China (population around a hundred million), Shan State in Burma, and Assam in India. This myth is highly propagandised by the powers that be today because 99 persent of the powers that be are ethnic Chinese, therefore it helps the Chinese justify their virtual monopoly of political and economic power in Thailand. As the Chairman of a Thai bank once said to me: "We only differ in the timing of when we came from China". However the Siamese have always eaten boiled rice and traditionally wear cotton fabrics, while all the ethnic groups closely related to the Lao traditionally (mostly still) eat sticky rice, produce their own silk and wear it, and have a great many other customs in common such as the patterns they weave on their textiles. There are a number of historical reasons for the linguistic relations, but after excluding words derived from Pali or Sanskrit and words related to law and administration, Thai vocabulary is far closer to its Mon-Khmer roots than it is to Lao. Lao dialects less strongly influenced by Siamese administration during the last few hundred years, such as Lue or Luang Prabang dialect (especially such as would be spoken in the market) are totally incomprehensible to Thai. The Buddhist calendar is essentially identical in Thailand, Laos, Cambodia, Burma and Sri Lanka, and the pali names are also identical. 77.188.90.146 (talk) 21:12, 23 June 2010 (UTC)Bhante

Wikify
To 208.147.1.1: By wikify, I mean that I have attempted to make the article conform to the Manual of Style so that it looks like a Wikipedia article. The principle aspects that apply to this article are: It must begin with a sentence, the subject of which is the title of the article; "See also" is a heading near the end of the article; a former version of the Wikipedia article being modified cannot be used as a reference; AD is to be written without periods; the ASCII dash '--' should be replaced by &mdash;. I have also corrected the categories so that both appear, and have italicized the titles of books. By the way, I am the author of Buddhist calendar and I have read Eade. — Joe Kress 07:11, Jan 19, 2005 (UTC)

Revising
This is rather an important article, because many others refer to it for clarification of lunatic dates; but it is also rather a mess. I'm currently working on revising it in my Sandbox. Anyone want to come play with me? Pawyilee (talk) 09:09, 6 May 2008 (UTC)
 * I went ahead and published my new version as I finally got around to reading Diller and found I had put a lot of BS in the old. For instance, Thai lunar months do have names, it's just that nobody uses them. So, I said as much but left the names out as Diller did not give Thai spellings. I also heavily revised his list at (5.3) Thai holidays and festivals regulated by the moon where he lists the last day of Moon 10 (name phatrabot) as Sa:t, food-cake presentation. I figured out the Thai spelling, and found it in the Online Royal Institute Dictionary [ORID] at สารท ๑ (สาด). (The ORID is more than a bit tricky to use.) But if you look at a current calendar, you'll find it named Tesagarn Kin Jae 9 Wan (Thai: เทศกาลกินเจ ๕ วัน) (sometimes prefixed begin), as the beginning of a Nine-day Vegetarian Festival. So, in the process I discovered we need an article on Vegetarian Festival (Thailand). Go-ogling up the subject returns many opinions that it is strictly a Chinese Buddhist phenomenon, and you can read a fairly good if un-scholarly article about it here. I feel sure Bangladeshi Madhu Purnima is related. In the latter, you can read about an elephant bringing fruit and a monkey bringing honey to Lord Buddha, and you can see those images in wats everywhere. Anyway, other bloggers think the Vegetarian Festival was invented by Thai Chinese Buddhists in the 19th C., first in Phuket but it has now spread to many other places, including a place on the calendar! Kin Jae กินเจ is also in the ORID, and if you see a restaurant displaying เจ in Chinese-like brush strokes, it's not the number 17 but the mark of a strictly vegetarian menu. I just don't know how to leap the no-original-research hurdle. Pawyilee (talk) 16:30, 22 June 2008 (UTC)
 * Someone started Vegetarian Festival and, so far,it only about the one in Phuket. Most of the pertinent information, however, is at Nine Emperor Gods Festival. Pawyilee (talk) 14:31, 23 June 2008 (UTC)
 * Any editor who can read Thai and wants to help might try เทศกาลสารท and เทศกาลสารทจีน. Pawyilee (talk) 14:50, 23 June 2008 (UTC)

I agree the article is a mess. A few corrections: wan ook phansa marks a new year for a monk in terms of the number of rainy seasons he has completed, but is not a New Year Day in any other sense. Wan khao phansa is totally irrelevant in this respect, unless he was ordained during the vassa in which case he still has an age of 0 even one day before the vassa ends the following year! An important purpose which the lunar calendar must fulfill is to allow people to determine correctly when the vassa starts. The insertion of the extra month after the eighth month is related to this, and allows the deviations of the lunar calendar from the seasons (especially the rainy season) to be corrected. It can be expected that in the days when the seasons could not be accurately predicted astronomically, the most crucial season which might arrive later than expected would be the rainy season - coming immediately after the hot and dry season. Thus if the eighth month arrives and passes by without the rains starting (and therefore, the ability to plant rice and for the monks, the obligatory vassa), then it makes sense to add an extra eighth month. Incidentally the seasons were described by the Buddha, and his classifications together with the rules for the monks form the foundation of the Thai lunar calendar (which was originally the only calendar), so the Thai lunar calendar doesn't make much sense divorced from Buddhism! All the lunar months have Pali names, some of which are almost universally known while others are rather little known nowadays. Traditionally even news broadcasts always started with the date in the Buddhist calendar. The Kathina season starts on the full moon day at the end of the vassa and ends the day before the following full moon, therefore the table is wrong in this respect. The actual Kathina can take place on any one day in this period, and will be different in different temples (but only one day in each temple). There are numerous systems for transcribing Thai, of which at least two are authoritative. The etymologically most logical is based on the derivation of Thai characters from Indian characters, but the problem is that all the stop consonants are phonetically switched in pairs, which accounts for all the painful contradictions with respect to the Royal Institute version. The vegetarian festival is derived from Mahayana Buddhism, and is related to the agricultural cycle. It is a politically inspired myth that the word Thai means free - there is no such connection. The word originally came from the Chinese word dai meaning big (with various pronunciations and tones in different Chinese dialects, including tai in South China), and was first used by the ancestors of the Lao to denominate the nobility in a rather artificial 4-caste social classification derived from the Indian caste system, but this did not survive because it was not compatible with the nature of Lao society. Later it came to mean person, or person from ... (eg taina tailang foreguard or rearguard, taidaing people from the Red River, taidam people from the Black River, tai Muang Luang people from Luang Prabang, tai Vieng people from Vientiane, tai meng luang Ailao Shan people from the great city of the Ailao mountains abbreviated to Shan by the Burmese and to tai luang by the Siamese, etc). This Lao word tai was misunderstood by Western missionaries to mean ethnic, and the hegemonist Siamese soldier and politician Field Marshal Phibul Songkhram exploited this for propaganda to try to take over large swathes of Laos, Cambodia, Vietnam, Southern China, Northern Burma and Assam State in India as the French and British colonialists started withdrawing from their colonies around the world. Your Sanskrit etymology is highly problematic. Above, your Tesagarn kin jae 9 wan conflicts with the Thai! I would advise against relying on Diller as a source - the cited article is highly uninformed and unprofessional. Diller even claims that the 7 day week is traditional, but it is a modern introduction from the West with no basis in traditional Asian culture. The traditional period is the 8 or sometimes 7 day quarter-moon period centered around the Buddhist uposatha days. In the early 20th century the Western week had no relevance to the ordinary rural Siamese, except when they had to deal with the administrative structures - however the government employees welcomed to take the chance of Saturday and Sunday holidays in addition to every uposatha day! 77.188.90.146 (talk) 23:25, 23 June 2010 (UTC)Bhante
 * That "Wan khao phansa is totally irrelevant in this respect", i.e., in counting New Years, is relevant to the article, and I deleted the "totally irrelevant" entry. Most of the rest of what Bhante added to this mess on the Talk page belongs not here but at Talk:Thaification. --Pawyilee (talk) 04:03, 24 June 2010 (UTC)
 * Kathin can be observed any day before the next full moon, but it is not accurate that a temple only does this one day (though it might have one main public day). In fact families and groups who want to participate will schedule a one (or multiple) day event at their home and one of those days go to the temple and make the offerings and have a ceremony with some of the monks. When this is done is a scheduled event in these cases. --Jeffmcneill (talk) 07:20, 1 February 2016 (UTC)

Cleanup Suggestions
--Lendorien (talk) 15:45, 7 January 2009 (UTC)
 * Years section should have some discussion at the beginning as to why the Thai calendar has different year lengths. This information is not presented and makes understanding the calendar hard to do. I assume it has something to do with the Lunar cycle and reading onward clarifies it, but it needs to be defined at the beginning of the year section in a clear way. I've tried to do this, but it needs to be checked by someone more knowledgable.
 * Some sections could be cleaned up and prosified to avoid the excessive use of bullet lists. I have done this with the month section to remove the excessive headings. I think it works, but what I've done should be checked.
 * The heavy use of bolding should be removed. It makes things hard to read
 * I've removed some of the language cues after they have been used the first time. Using them over and over clutters the article and makes it hard to read. This should probably be done for the whole article.
 * Some effort needs to be made to rewrite some of this material to clarify it. It seems to be unnecessarily vague in places.
 * This article contains almost no references for this material. Sourcing is needed.
 * I've done some of the changes listed above. --Lendorien (talk) 18:00, 8 January 2009 (UTC)

How were years counted or named?
How did the traditional Thai lunar calendar count or name years? For example, the year 1601 by Western reckoning was the 6th year of the imperial era of Keicho in Japan, and the 30th year of the reign of the Wanli Emperor in China. Did the Thai calendar use some kind of era name, like China and Japan? Or did it count purely using numbers, like the Christian, Jewish, and Muslim calendars? Or did it not count at all, simply identifying the year as a Year of the Rat or a Year of the Ox or whatever without actually counting years? LordAmeth (talk) 01:10, 5 February 2010 (UTC)

There was a year numbering system known as Chula Sakarat, which is claimed to have been used since the Ayutthaya (and even Sukhothai) periods. I'm not sure to what extent they were used, or what documenting evidence there actually is. Paul_012 (talk) 04:26, 5 February 2010 (UTC)

New Year Animal
Someone added, "However, the ethnic Thais will consider the year to assume a new zodiacal animal at Songkran (13 April), not at Chinese New Year." TRUE: Indic-origin Songkran is considered by many ethnic groups, including Tai, to mark the start of a new year, but authoritative citation needed to support the claim, which is FALSE as far as I know, that any of the groups, especially the Thai, use this occasion to change to the next Chinese Animal of the Year. --Pawyilee (talk) 14:05, 16 February 2010 (UTC)

 * If you look at the dates printed in Thai-language newspapers, you will see that the animal year does change at Songkran. --Paul_012 (talk) 15:17, 16 February 2010 (UTC)

 * I can confirm this, in the book by J.C.Eade (ISBN 90-04-10437-2) it is said that the only thing not sure is whether the year change occurred at the begin of the lunar month before Songkran as claimed by e.g. Coedes, whereas an inscription from 1777 CE suggests that the change occurred at Songkran itself. andy (talk) 20:51, 16 February 2010 (UTC)
 * Okay. I'll check a paper! --Pawyilee (talk) 03:05, 17 February 2010 (UTC)

I am that "someone", and as a Thai I can only confirm that we do consider our yearly animal changed at Songkran, and not Chinese New Year. Try the Prommachat text of Thai astrology, (although I doubt if an English translation is available...) or ask any Thais. Oh, by the way, after your checking, don't you think an apology might be in order for claiming that my "claim" is false? Well, as a Thai would say, Never mind - Mai pen rai! 122.0.3.123 (talk) 03:30, 18 February 2010 (UTC)thaivisitor
 * I wrote FALSE as far as I know, and finding out that what I thought I knew was what was false sent me scrambling after the strikethrough trick. And I wish Ahoerstemeier or Paul would replace . And now the Twelve-year animal cycle names table New Year's Day column must be changed to "Chinese New Year's Day." I'm trying to figure out how best to do that over in my sandbox. --Pawyilee (talk) 12:02, 18 February 2010 (UTC)
 * Please look in my sandbox now, and see if you can improve it. I don't know how to center tables, or center info in columns (below the headings, which are centered.) --Pawyilee (talk) 12:44, 18 February 2010 (UTC)
 * I'll add the citation probably tonight, then I can add the page number as well. By the way, you're welcome to create an account here, then it will be more comfortable to contact you, especially if you use more than one IP. And an account is even more anonymous than the IP, which can trace where you come from... andy (talk) 13:21, 18 February 2010 (UTC)

What about the table in my sandbox? --Pawyilee (talk) 14:55, 18 February 2010 (UTC)
 * Posted --Pawyilee (talk) 08:48, 19 February 2010 (UTC)
 * Took my sandbox back. --Pawyilee (talk) 13:16, 22 February 2010 (UTC)

Wetsandon
Moon 3 Wain 8 add for Wetsandon ?--Pawyilee (talk)

Etymology of patithin
Just to post a note here.

The word thin (ทิน) in patithin (ปฏิทิน, "calendar") is not from thinnakon (ทินกร, "sun"). The word thin is from Sanskrit dina, meaning day or days.

Patithin is composed of pati (ปฏิ, from Sanskrit paṭi, meaning "for, specific, separate, individual or against") and thin (ทิน, "day"). Patithin is thus from Sanskrit paṭidina and literally means: for days, specific days, day by day, day against day, each day, daily, etc.

So, thin is not from thinnakon. Thinnakon is composed of thinna (ทิน, "day" / thin is pronounced thinna when forming the first part of a compound word according to the rule of "samat" (สมาส)) and kon (กร, from Pali or Sanskrit, kara, meaning "doer or maker"). Thinnakon, from Sanskrit dinakara, literally means one who makes the day, that is, the sun.

The opposite word is rattikon (รัตติกร), from ratti (รัตติ, from Pali ratti, meaning "night") + kon. Rattikon, from Pali rattikara (Sanskrit equivalent is rātrikara), literally means one who makes the night, that is, the moon.

--Aristitleism (talk) 17:35, 16 January 2014 (UTC)

Use of colour
The red and yellow is rather garish, isn't it? 86.132.220.76 (talk) 11:21, 1 August 2015 (UTC)

 * Rather garish? You are an exemplar of understatement. Change it straightaway. Seligne (talk) 12:19, 1 August 2015 (UTC)

 * I have to agree, garish indeed. And the table doesn't really add much information. A list with the same info would be useful. --Jeffmcneill (talk) 07:48, 1 February 2016 (UTC)

Proposed merging of Thai lunar calendar and Thai solar calendar
While one can say there are distinct lunar and solar Thai calendars, in actual practice these two always go together in a proposed Thai lunisolar calendar. That is, there are no actual manufactured calendars which do not have both kinds of events (solar, aka Jan 1, Apr 13-15, May 1, etc.) and lunar (all the lunar Buddhist holidays, including Makha Bucha through to Loi Krathong.

 * Thai lunar calendar
 * Thai solar calendar

Proposal: Thai lunisolar calendar And changing the previous two articles into redirects to the proposed article

Having two separate entries creates confusion. One entry with discussion of both purely solar and purely lunar events and origins would be much more informative and help visitors understand both topics.

See also discussion at:

External links modified
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"Irregular" -- Thai Lunar Calendar page doesn't explain ... the Thai Lunar Calendar!!
I hope even the non-mathematical among you will grasp that Thai lunar dates cannot be determined if we can't even find the beginning of Month 1!! From this page all we learn is what is NOT -- it isn't Songkran; it isn't Chinese New Year -- and what it USUALLY is -- "usually sometime in December." Good enogugh for tourists chatting over beers at a Thai beach? I guess so. But this should NOT be the standard for Wikipedia.

The article states "An extra day or an extra 30-day month is intercalated at regular intervals." Anyone have a cite for this? Tell us what the "regularity" is and we can devise an algorithm to determine the Thai months. Until we get a cite for "regular" I've changed the text to read "irregular." Jamesdowallen (talk) 09:13, 21 November 2018 (UTC)

Based on the SuriyaYatra?
The article says that the TLC is "based on the SuriyaYatra" but there is no information about this SuriyaYatra. (SuriyaYatra links to this article for the moment). Can anyone clarify? --John Maynard Friedman (talk) 14:46, 25 October 2021 (UTC)

title: Talk:Thai lunar calendar


text:
Dynatron oscillator

In electronics, the dynatron oscillator, invented in 1918 by Albert Hull at General Electric, is an obsolete vacuum tube electronic oscillator circuit which uses a negative resistance characteristic in early tetrode vacuum tubes, caused by a process called secondary emission. It was the first negative resistance vacuum tube oscillator. The dynatron oscillator circuit was used to a limited extent as beat frequency oscillators (BFOs), and local oscillators in vacuum tube radio receivers as well as in scientific and test equipment from the 1920s to the 1940s but became obsolete around World War 2 due to the variability of secondary emission in tubes.

Negative transconductance oscillators, such as the transitron oscillator invented by Cleto Brunetti in 1939, are similar negative resistance vacuum tube oscillator circuits which are based on negative transconductance (a fall in current through one grid electrode caused by an increase in voltage on a second grid) in a pentode or other multigrid vacuum tube. These replaced the dynatron circuit and were employed in vacuum tube electronic equipment through the 1970s.

How they work
The dynatron and transitron oscillators differ from many oscillator circuits in that they do not use feedback to generate oscillations, but negative resistance. A tuned circuit (resonant circuit), consisting of an inductor and capacitor connected together, is "almost" an oscillator: it can store electric energy in the form of oscillating currents, "ringing" analogously to a tuning fork. If a tuned circuit could have zero electrical resistance, once oscillations were started it would function as an oscillator, producing a continuous sine wave. But because of the inevitable resistance inherent in actual circuits, without an external source of power the energy in the oscillating current is dissipated as heat in the resistance, and any oscillations decay to zero.

In the dynatron and transitron circuits, a vacuum tube is biased so that one of its electrodes has negative differential resistance. This means that when the voltage on the electrode with respect to the cathode is increased, the current through it decreases. A tuned circuit is connected between the electrode and the cathode. The negative resistance of the tube cancels the positive resistance of the tuned circuit, creating in effect a tuned circuit with zero AC resistance. A spontaneous continuous sinusoidal oscillating voltage at the resonant frequency of the tuned circuit is generated, started by electrical noise in the circuit when it is turned on.

An advantage of these oscillators was that the negative resistance effect was largely independent of frequency, so by using suitable values of inductance and capacitance in the tuned circuit they could operate over a wide frequency range, from a few hertz to around 20 MHz. Another advantage was that they used a simple single LC tuned circuit without the taps or "tickler" coils required by oscillators such as the Hartley or Armstrong circuits.

Dynatron oscillator

In the dynatron a tetrode tube is used. In some tetrodes the plate (anode) has negative differential resistance, due to electrons knocked out of the plate when electrons from the cathode hit it, called secondary emission. This causes a downward "kink" in the plate current vs. plate voltage curve (graph below, grey region) when the screen grid is biased at a higher voltage than the plate, as described below. This negative resistance was mostly a feature of older tubes, of 1940s or earlier vintage. In most modern tetrodes, to prevent parasitic oscillations the plate is given a coating which drastically reduces the unwanted secondary emission, so these tubes have virtually no negative resistance "kink" in their plate current characteristic, and cannot be used in dynatron oscillators.

The tetrode wasn't the only tube which could generate dynatron oscillations. Early triodes also had secondary emission and thus negative resistance, and before the tetrode was invented they were used in dynatron oscillators by biasing the control grid more positive than the plate. Hull's first dynatron oscillator in 1918 used a special "dynatron" vacuum tube of his own design (shown above), a triode in which the grid was a heavy plate perforated with holes which was robust enough to carry high currents. This tube saw little use as standard triode and tetrodes could function adequately as dynatrons. The term "dynatron" came to be applied to all negative resistance oscillations in vacuum tubes; for example the split-anode magnetron was said to work by "dynatron oscillation".

An advantage of the dynatron circuit was that it could oscillate over a very wide frequency range; from a few hertz to 20 MHz. It also had very good frequency stability compared to other LC oscillators of that time, and was even compared to crystal oscillators. The circuit became popular after the advent of cheap tetrode tubes such as the UY222 and UY224 around 1928. It was used in beat frequency oscillators (BFOs) for code reception and local oscillators in superheterodyne receivers as well as in laboratory signal generators and scientific research. RCA's 1931 prototype television used two UY224 tubes as dynatron oscillators to generate the vertical deflection (28 Hz) and horizontal deflection (2880 Hz) signals for the CRT's deflection coils.

However the dynatron had some drawbacks. It was found that the amount of secondary emission current from the plate varied unpredictably from tube to tube, and also within a single tube over its operating life; eventually it would stop oscillating. When replacing the tube, several might have to be tried to find one that would oscillate in a circuit. In addition, since dynatron oscillations were a source of instability in amplifiers, the tetrode's main application, tube manufacturers began applying a graphite coating to the plate which virtually eliminated secondary emission. By 1945 the use of the dynatron circuit was declining.

Secondary emission
[[Image:UY224 tetrode plate current negative resistance.svg|thumb|upright=1.1|Plate current IP and screen grid current IG2 vs plate voltage VP curves of RCA's UY224 tetrode which came out in 1929, showing negative resistance region (grey).

Screen grid potential VG2 = 75 V

Control grid potential VG2 = −1.5 V

In this tube, secondary emission was sufficiently strong that it not only caused negative resistance (a declining slope) but reversed the plate current; more electrons left the plate than arrived at it. ]]

In an electron tube, when electrons emitted by the cathode strike the plate, they can knock other electrons out of the surface of the metal, an effect called secondary emission. In a normal tetrode amplifier this is an unwanted effect, and the screen grid next to the plate is biased at a lower potential than the plate, so these secondary electrons are repelled and return to the plate due to its positive charge.

However, if the screen grid is operated at a higher potential than the plate, the secondary electrons will be attracted to it, and return to ground through the screen grid supply. This represents a current of electrons IG2 away from the plate, which reduces the net plate current IP below the cathode current IC
 * $$I_P = I_C - I_{G2} \,$$

Higher plate voltage causes the primary electrons to hit the plate with more energy, releasing more secondary electrons. Therefore, starting at the voltage at which the primary electrons have enough energy to cause secondary emission, around VP = 10V, there is an operating region (grey) in which an increase in plate voltage causes more electrons to leave the plate than the additional electrons arriving at the plate, and therefore a net reduction in plate current.

Negative resistance
Since in this region an increase in plate voltage causes a decrease in plate current, the AC plate resistance, that is the differential output resistance of the tube, is negative:
 * $$r_P = {\Delta V_P \over \Delta I_P} < 0 \,$$

As with other negative differential resistance devices like the tunnel diode, this negative resistance can be used to create an oscillator. A parallel tuned circuit is connected in the plate circuit of the tetrode. The circuit will oscillate if the magnitude of the negative plate resistance is less than the parallel resistance R of the tuned circuit, including any load connected to the oscillator.
 * $$|r_P| < R \,$$

The frequency of oscillation is close to the resonant frequency of the tuned circuit.
 * $$f = {1 \over 2\pi}\sqrt{1 \over LC} \,$$

Design
As can be seen from the graphs, for dynatron operation the screen grid had to be biased at a considerably higher voltage than the plate; at least twice the plate voltage. The plate voltage swing is limited to the negative resistance region of the curve, the downward "kink", so to achieve the largest output voltage swing, the tube should be biased in the center of the negative resistance region.

The negative resistance of older tetrode tubes was around 10kΩ - 20kΩ, and can be controlled by varying the control grid bias. If the magnitude of the negative resistance |rP| is just small enough to start oscillation, just a little smaller than the positive resistance R of the tuned circuit, the oscillation frequency will be very stable, and the output waveform will be almost sinusoidal. If the negative resistance is made significantly smaller than the positive resistance, the voltage swing will extend into the nonlinear part of the curve, and the peaks of the sine wave output will be flattened ("clipped").

Transitron oscillator

The transitron oscillator, invented by Cledo Brunetti in 1939, (although a similar effect was observed in tetrodes by Balthasar van der Pol in 1926, and Edward Herold described a similar oscillator in 1935 ) is a negative resistance oscillator circuit using a pentode vacuum tube, in which, instead of the plate, the screen grid has negative resistance due to being coupled to the suppressor grid. See the circuit at right. In the transitron, the screen grid is biased at a positive voltage (battery B1) above the plate voltage while the suppressor grid is biased negatively (battery B2), at or below the cathode voltage. Therefore, all the electrons will be reflected by the negative suppressor grid and none will get through to the plate. The reflected electrons will instead be attracted to the screen grid, so the screen current will be high while the plate current will be zero. However, if the suppressor grid voltage is increased, as it approaches zero (the cathode voltage) electrons will begin to pass through it and reach the plate, so the number diverted to the screen grid, and thus the screen current, will decrease. Since the other grids don't take significant current the cathode current $$\scriptstyle I_\text{C}$$ is split between the plate $$\scriptstyle I_\text{P}$$ and the screen grid $$\scriptstyle I_\text{G2}$$:
 * $$I_\text{G2} = I_\text{C} - I_\text{P} \,$$

The division of current between the screen grid and plate is controlled by the suppressor voltage. This inverse relationship is indicated by saying the transconductance between the screen and suppressor grid (the change in screen current ΔIG2 divided by the change in suppressor voltage ΔVG3) is negative.

Since the suppressor grid voltage and not the screen grid voltage controls the screen current, if the suppressor and screen grid are coupled together with a capacitor (C2) so there is a constant potential difference between them, increasing the screen grid voltage will increase the suppressor voltage, resulting in a decrease in screen current. This means the screen grid has negative differential resistance with respect to the cathode, and can be used to create oscillations.

In the transitron circuit, the screen and suppressor grids are coupled with a bypass capacitor (C2) which has a low impedance at the oscillation frequency, so they have a constant potential difference. The parallel tuned circuit (C1-L) is connected between the screen grid and the cathode (through battery B1). The negative resistance of the screen grid cancels the positive resistance of the tuned circuit, causing oscillations. As in the dynatron oscillator the control grid can be used to adjust the negative resistance.

Since the transitron oscillator didn't depend on secondary emission it was far more reliable than the dynatron. However, because the screen grid is not designed to handle high power, the oscillator's output power is limited. Other tubes with multiple grids beside the pentode, such as the hexode and pentagrid converter tube, have been be used to make similar negative transconductance oscillators. Pentode tubes used in this circuit have a negative transconductance of only around -250 microsiemens, giving a negative resistance of -4000Ω. Tubes with more grids, such as the pentagrid converter, can be used to make transitron oscillators with higher transconductance, resulting in smaller negative resistance.

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

title: Dynatron oscillator


text:
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I have worked on a number of pages beginning with Z, mostly around Zulus and Zimbabwe.

Zulus
On Zulus and South Africa, I have either started or worked on the following pages :-

Albert Lutuli, Anglo-Zulu War, Anthony Durnford, Arthur Goldreich, Bantu, Battle of Gqokli Hill, Battle of Isandlwana, Cetshwayo, Dingane, Dingiswayo, Dinizulu, Eshowe, Fort Tenedos, Frederic Augustus Thesiger, 2nd Baron Chelmsford, Goodwill Zwelethini kaBhekuzulu, Henry Bartle Frere, Hlatikhulu Forest, Impi, Jacob Zuma, John Dunn, John William Colenso, KwaDukuza, Lancaster House Agreement, Mangosuthu Buthelezi, Mfecane, Moshoeshoe I, Mpande, Mswati III of Swaziland, Mzilikazi, Napoleon Eugene, Prince Imperial, Ndlela kaSompisi, Ndwandwe, Nguni, Nongoma, Noon gun, Raymond Mhlaba, Rivonia Trial, Rorke's Drift, Route 62, Sangoma, Shaka, Sir Henry Bartle Frere, 1st Baronet, Tugela River, Ulundi, Umhlanga, University of Fort Hare, Usibepu, Z.K. Mathews, Zulu, Zulu Civil War, Zulu language, Zululand, Zwelinzima Vavi

Zimbabwe
Abel Muzorewa, Edson Zvobgo, Enos Nkala, Gideon Gono, Gukurahundi, Guy Clutton-Brock, Herbert Chitepo, Ian Smith, Jonathan Moyo, Joseph Msika, Joshua Nkomo, Josiah Tongogara, Joyce Mujuru, Lancaster House Agreement, Land reform in Zimbabwe, Margaret Dongo, Morgan Tsvangirai, Movement for Democratic Change, Ndabaningi Sithole, Phillip Chiyangwa, Robert Mugabe, Roy Bennett, Simon Muzenda, UANC, Unilateral Declaration of Independence (Rhodesia), Zanu-PF, Zimbabwe, Zimbabwe African National Union, Zimbabwe parliamentary elections, 2005

Other
Other pages, mostly from Africa :

Civil war in Côte d'Ivoire, History of Rwanda, Mswati III of Swaziland, Paul Kagame, Rwandan Genocide and related pages, SAFE (cable), Corruption in Kenya, History of salt, Nigerian general election, 2007, Corruption in Kenya, Goldenberg scandal

Travel
I grew up in Kenya, went to public school in the United Kingdom, studied Engineering at Sidney Sussex College, post-grad at Uxbridge University, lived in Tooting, moved to Bristol, worked for British Aerospace and then Inmos, learned and programmed Parallel processing with the Transputer, moved to Columbia, MD, travelled on business up and down the East Coast, travelled around India and Nepal for 3 months, moved to Colorado Springs, CO, did a lot of theatre there with the Star Bar Players, did a long trip though Kenya, Tanzania, Rwanda, Burundi, Cameroon, Nigeria, Benin, Togo, Ghana, Cote d'Ivoire, Burkina Faso, Mali, Dogon territory, Senegal, The Gambia. Later, I moved to South Africa, and I now live in Cape Town, actually Muizenberg, though I love Eshowe also.

Trivia
A little piece of Wikipedia history I found ..

Tools

 * Geo-tagging User:Dschwen, Create coor tags

title: User:Wizzy


text:
List of birds of South Asia

The birds of South Asia include the species found in India, Pakistan, Nepal, Bangladesh, Bhutan, Sri Lanka and the Maldives.

This is not only a huge geographical area, but has a range of habitats extending from deserts to rainforest, and from the world's highest mountains to coastal mangrove swamps.

These factors, coupled with the tropical climate, result in a large numbers of bird species, some 1300. As would be expected in the tropics, most of these, more than 1,000 species, are resident within the South Asia. The rest are mainly winter visitors from further north in Eurasia. Only eighteen species are purely summer visitors to the subcontinent.

141 species are endemic to the region, and 26 of these are endemic to Sri Lanka.

Because of the large number of species, the lists are divided into four parts.
 * part 1 – Megapodes, Galliformes, Gruiformes and near passerines
 * part 2 – remainder of non-passerines
 * part 3 – passerines from pittas to cisticolas
 * part 4 – passerines from Old World warblers to buntings

title: List of birds of South Asia


text:
Childline

Childline is a British counselling service for children and young people aged up to 18 in the United Kingdom provided by the National Society for the Prevention of Cruelty to Children. They deal with any issues which cause distress or concern; some of the most common issues include child abuse, bullying, mental illness, parental separation and or divorce, teenage pregnancy, substance misuse, neglect, and psychological abuse.

Confidentiality
ChildLine Counsellors will not record calls but write down case notes of calls and sometimes counselling supervisors may also listen in to calls to make sure that they can help the best they can. If there is an immediate serious concern for someone's welfare or they are worried a child's life is in danger, notes may be passed on to relevant bodies, including the Police and the NHS Callers are not required to provide their name; they can give as little or as much personal information as they wish.

History
In 1986 Esther Rantzen, presenter of consumer television show That's Life!, suggested to the BBC that they create "Childwatch", a programme about child abuse that was screened on 30 October 1986 on BBC1, the aim being to try to detect children at risk before their lives were in danger. Viewers were asked if they would take part in the survey in an edition of That's Life!. A helpline was opened after the programme so that any child currently suffering abuse could call for help. Rantzen, together with her BBC producers Sarah Caplin and Ritchie Cogan, therefore suggested they should create a helpline specifically for children in danger or distress, to be open throughout the year, 24/7, and launch it on the programme. The project was made possible by a benefactor Ian Skipper who underwrote the charity for the first three years.

Childline joined the National Society for the Prevention of Cruelty to Children (NSPCC) in February 2006, and extra resources were pledged in an attempt to ensure that no child's call goes unanswered.

UK operations
Childline has 12 counselling centres around the UK and one home based team, staffed largely by volunteers. The bases are located in Glasgow, Aberdeen, Manchester, Liverpool, Prestatyn, Birmingham, Nottingham, London, Belfast and Foyle, supported by the online only centres at Leeds and Cardiff and the Virtual Base. A restructure in 2011 saw the closure of the Childline bases in Exeter and Edinburgh, with Swansea relocating to Cardiff. As many as 4,500 phone Childline every day, though only 2,500 of these callers can be answered due to lack of resources. Since the merger with the NSPCC the service has expanded, and depends on public generosity to pay for the phone calls.

Childline raises funds through several channels, including direct donations through the NSPCC, partnerships, events such as The X Factor Childline Ball and through third-party fundraising organisations such as Justgiving.

Virtual Base
Childline's virtual base was started in April 2020 in response to the COVID-19 pandemic. Counsellors in the virtual base answer emails sent by children and young people from their Childline accounts from their own home.

Childline Scotland
Following Childline's merger with NSPCC in 2006, Childline Scotland was run by Children 1st under contract, available to all young people in Scotland up to 18 years of age. It had at that time bases in Glasgow, Aberdeen and Edinburgh. The Edinburgh base has since closed. As of March 2012, Childline Scotland is run directly by the NSPCC. In 2011 the NSPCC in Scotland began to work with partners to introduce new services for children and families.

International
Similar helplines using the name Childline have been formed in a number of countries. As of May 2013 these included Childline Botswana, Childline India, Childline Ireland (Leanbh), チャイルドライン (Japan), (Lithuania), Childline South Africa, National Child Protection Authority of Sri Lanka, Child Helpline Tanzania, Childline Trinidad and Tobago, as well as organizations in Namibia, Trinidad and Tobago, Gibraltar, Kenya, Zambia, and Zimbabwe. Some of these are independent charities; others have been set up by existing children's charities or more general helplines.

Childline in Ireland is run by the Irish Society for the Prevention of Cruelty to Children (ISPCC). It was set up in 1989. In 2006 a text and online service, in association with Zamano, was established to increase the availability of the listening service for children in Ireland.

Childline Uganda helps people infected and affected by HIV/AIDS live a better life.

Telephone number
The freephone number, 0800 1111, was one of the first 0800 numbers to be issued in the United Kingdom. Before BT allocated this number to Childline, 0800 1111 was used as a test line number by technicians. Other early allocated 0800 numbers were 10 digit, including the prefix. Childline's number is one of only a handful of 8 digit 0800 UK numbers to ever have been allocated and the only one still in use. Calls to the number do not appear on the phone bill.

Childline is also available on the harmonised European number for child helplines, 116111. Young people can also contact Childline through their website, via 1-2-1 counsellor chat, SignVideo, Ask Sam and the 'write an email' feature.

title: Childline


text:
Anti-thymocyte globulin

Anti-thymocyte globulin (ATG) is an infusion of horse or rabbit-derived antibodies against human T cells and their precursors (thymocytes), which is used in the prevention and treatment of acute rejection in organ transplantation and therapy of aplastic anemia due to bone marrow insufficiency.

Uses
Two antithymocyte globulin (ATG) agents licensed for clinical use in the United States are Thymoglobulin (rabbit ATG, rATG, Genzyme) and Atgam (equine ATG, eATG, Pfizer). Thymoglobulin and Atgam are currently licensed for use in the treatment of renal allograft rejection; Atgam is additionally licensed for use in the treatment of aplastic anemia. Both drugs are used in off-label applications, especially as immunosuppression induction agents before and/or during kidney transplantation. A rabbit anti-T lymphocyte globulin made by Neovii Pharmaceuticals is marketed outside of the United States under the name Grafalon.

ATG administration very substantially reduces immune competence in patients with normal immune systems, through a combination of actions, some explicitly understood and some more hypothetical. rATG in particular effects large reductions (through cell lysis) in the number of circulating T lymphocytes, hence preventing (or at least delaying) the cellular rejection of transplanted organs. However, medical opinion remains divided as to when the benefit of this profound reduction in T cells outweighs the concomitant increased risks of infection and malignancy.

In the United States it is frequently given at the time of the transplant to prevent graft-versus-host disease, although many European centers prefer to reserve its use for the treatment of steroid-resistant acute rejection, as European centres generally serve more homogeneous populations and rejection tends to be less of a problem.

Complications and alternatives
ATG use can induce cytokine release syndrome, and has been thought to increase the risk of post-transplant lymphoproliferative disorder (PTLD); however, this association may not apply when lower dosing regimens are used. There is some evidence to suggest that inducing immunosuppression with rATG at organ transplantation may create conditions in the patient's immune system favorable to the development of immunological tolerance, but the exact basis for such a development remains largely speculative. Temporary depletion of the T-cell population at the time of the transplant also risks delayed acute rejection, which may be missed and cause severe damage to the graft.

Anti-IL-2Rα receptor antibodies such as basiliximab and daclizumab are increasingly being used in place of ATG as an induction therapy, as they do not cause cytokine release syndrome and (theoretically) improve the development of tolerance.

The cytokine release syndrome associated with ATG administration frequently causes high grade fevers (over 39 °C), chills, and possibly rigors during administration, for which reason steroids (normally methylprednisolone), diphenhydramine 25–50 mg, and acetaminophen 650 mg are usually co-administered. Such adverse reactions can often be controlled by slowing the infusion rate.

History
The first report of immunizing an animal of one species (guinea pig) against the immune cells of another species (mouse lymphocytes) was by Élie Metchnikoff in 1899. He reported injecting cells recovered from mouse lymph nodes into Guinea pigs and waiting for the immunization to result in the accumulation of anti-mouse antibodies in the Guinea pig blood. When he subsequently collected serum from these Guinea pigs and injected it into normal mice he observed a marked depletion in the number of circulating mouse lymphocytes.

Status in graft-versus-host disease
Rabbit ATG has been used in two randomised trials to reduce acute graft versus host disease in recipients receiving progenitor cell transplants. While higher doses (15 mg/kg) reduced acute graft versus host this was offset by increased infections. However a long term follow up showed that at both high and low (7.5 mg/kg) doses chronic graft versus host was reduced. A similar trial of anti-lymphocyte globulin showed a trend in reduction of acute graft versus host that was not statistically significant, but a reduction in chronic graft versus host. The Canadian Blood and Marrow Transplant Group is currently conducting the first randomised trial in chronic graft versus host using an even lower dose of rabbit ATG (4.5 mg/kg) in an attempt to confirm these observations. The endpoint is the reduction in the proportion of patients with chronic graft versus host at 1 year, off immunosuppressants.

title: Anti-thymocyte globulin


text:
Saint Michael's College

Saint Michael's College (St. Mikes or Saint Michael's) is a private Roman Catholic college in Colchester, Vermont. Saint Michael's was founded in 1904 by the Society of Saint Edmund. It grants Bachelor of Arts and Bachelor of Science degrees in more than 40 majors to about 1,200 undergraduate students. Housing availability is guaranteed for all four years, and 92% of students live on campus.

History
In 1889, priests from the Society of Saint Edmund fled to the United States after widespread anti-clericalism swept France. In 1904, they opened Saint Michael's Institute with an initial investment of $5,000. Thirty-four students aged 10 to 22 enrolled, with a tuition and board fee of $105. Slowly, the school discontinued its high school program. Gradually, the school transitioned from an academy to a traditional residential college. In 1939, graduate programs were offered for the first time.

Saint Michael's Playhouse was opened in 1947, bringing professional summer theater to Vermont, and giving students the chance to work behind the scenes.

Before the 1950s, classes at Saint Michael's were small, with just a few dozen Michaelmen in any class. In the 1950s, the college expanded to hundreds of students per class. To manage the influx of GI Bill students after World War II, Saint Michael's acquired temporary housing in the form of military barracks from Fort Ethan Allen in Colchester.

In the 1950s, freshmen were required to wear a dress shirt, coat, and tie to every class and for the evening meal. All dorm students said the rosary before retiring.

About 130 refugees from the Hungarian Revolution of 1956 came to the college. Most of them, already well-educated, came to learn English.

In April 1970, the Board of Trustees approved a proposal by then-president Bernard Boutin to become a co-educational institution. In 1972, the first four female graduates of Saint Michael's received their degrees.

Presidents

 * 1) Amand Prével (1904–1907)
 * 2) Brandon M. Cohane (1907–1913)
 * 3) Edmund M. Total (1913–1919)
 * 4) William Jeanmarie (1919–1931)
 * 5) Eugene Alliot (1931–1934)
 * 6) Leon E. Gosselin (1934–1940)
 * 7) James H. Petty (1940–1946)
 * 8) Daniel P. Lyons (1946–1952)
 * 9) Francis E. Moriarty (1952–1958)
 * 10) Gerald E. Dupont (1958–1969)
 * 11) Bernard L. Boutin (1969–1974)
 * 12) Francis E. Moriarty (1974–1976)
 * 13) Edward L. Henry (1976–1985)
 * 14) Paul J. Reiss (1985–1996)
 * 15) Marc A. vanderHeyden (1996–2007)
 * 16) John J. Neuhauser (2007–2018)
 * 17) Lorraine Sterritt (2018–2023)
 * 18) Richard Plumb (2023-Present)

Campus
The college consists of two campuses, the Main (also called South) and the North.

The main campus is the original and largest, with most of the classrooms, administration buildings, and residence halls. The Quad is anchored by Durick Library to the west and the Chapel of Saint Michael the Archangel to the east. The three academic halls, Cheray Hall, Jeanmarie Hall, and Saint Edmund's Hall, along with the McCarthy Arts Center line the Quad to the south. The Alliot Student Center and the four underclass residence halls wall the Quad on the north.

Sustainability
Saint Michael's has taken many steps towards sustainability over the years. It was named the first fair trade school in Vermont. Along with the initiatives in the cafeteria, Saint Michael's has an organic garden that started in 2008 and has grown into a huge project for students and faculty alike. The garden utilizes student volunteers through the Mobilization of Volunteer Efforts (MOVE) program and also works with summer interns and crew members to prepare the vegetables for Farm Stands that run from mid-summer through the beginning of fall. The school also provides a free CCTA (Chittenden County Transportation Authority Bus Route) commuter pass to all students, staff, and faculty. To improve water conservation, dual-flush handles for toilets have begun to be installed in various buildings around campus. All campus showerheads and sink aerators are low-flow. Saint Michael's College also took the St. Francis Pledge, a promise, and commitment by Catholic individuals, families, parishes, organizations, and institutions to live their faith by protecting the environment and advocating on behalf of people in poverty who face the harshest impacts of global climate change. As part of the college's ban on bottled water, the Office of Sustainability has installed several water bottle fill stations throughout campus, allowing students to more easily use their reusable water bottles.

Housing
Students at Saint Michael's College live in a variety of different housing facilities. All housing is single-sex by floor or wing.

Academics
Classes are small and hands-on learning is emphasized, with a student-to-teacher ratio of 12:1 Saint Michael's houses the following honors: Phi Beta Kappa; Delta Epsilon Sigma, the Catholic honor society; Pi Sigma Alpha for Political Science; Omicron Delta Epsilon for Economics; Phi Alpha Theta for History; Kappa Delta Pi for Education; Psi Chi for Psychology; Sigma Xi for Science and Technology; Pi Mu Epsilon for Mathematics; Beta Beta Beta for Biology; Kappa Tau Alpha for Journalism and Mass Communication (the only KTA chapter nationwide housed at a small college); and Sigma Beta Delta for Business, Management, and Administration. Four Saint Michael's professors have been named the CASE/Carnegie Foundation Vermont Professor of the Year. Saint Michael's College is accredited by the New England Commission of Higher Education.

Undergraduate
Undergraduate programs include over 30 majors and minors, combined with a liberal studies curriculum and experiential learning requirement. Emphasis is placed on independent study, independent research, internships, and foreign study. Eligible students can also participate in the college's Honors Program. The most popular undergraduate majors at Saint Michael's College, based on 2021 graduates, were:
 * Business Administration & Management (42)
 * Biology/Biological Sciences (41)
 * Psychology (34)
 * Environmental Studies (22)
 * Mass Communication/Media Studies (18)

Study abroad
Students may participate in study abroad programs, which cost the same as a semester on campus. Students can choose from over 100 different programs located around the globe and can choose a program by location or language, or from a variety of special Saint Michael's programs. Over a third of students choose to study abroad.

Culture
Nearly 100% of students live on campus in residence halls and townhouses. There are over 40 student organizations. There are no fraternities or sororities. Other activities include Saint Michael's Fire and Rescue student volunteer first responders, Student Association, Adventure Sports Program, Campus Ministry, the campus radio station WVTX, club sports, student musical and play productions, the Saint Michael's Chorale, Vermont Gregorian Chant Schola, open mic nights and various instrumental and vocal ensembles. Christmas and spring semi-formal dances are held. Athletics facilities include a fitness room, racquetball and an indoor track and swimming pool. Trails surround the campus for cross-country running or mountain biking.

Athletics
There are 21 varsity sports (10 for men, 11 for women) and over 20 intramural teams. Saint Michael's varsity sports teams are called the Purple Knights. The school colors are purple and gold. Eighteen varsity teams participate in the NCAA's Division II Northeast-10 Conference; Alpine and Nordic skiing are members of the multi-divisional Eastern Intercollegiate Ski Association (EISA), and women’s ice hockey competes in Division I New England Women's Hockey Alliance. Approximately 25% of students participate in a varsity sport. For men: Baseball, basketball, cross country, golf, ice hockey, lacrosse, skiing (Alpine and Nordic), soccer, swimming & diving, and tennis. For women: basketball, cross country, field hockey, ice hockey, lacrosse, skiing, soccer, softball, swimming & diving, tennis, and volleyball. Student-led programs include men's and women's rugby, billiards, ping pong, floor hockey, volleyball, and indoor soccer. Tournaments are also scheduled throughout the academic year. Yoga, jazzercise, kickboxing, cardio step, and pilates courses are offered weekly. First Aid and CPR training/certification is also offered.

Saint Michael's Playhouse
Saint Michael's Playhouse is the college's professional equity summer theater. The Playhouse is a member of the Council of Resident Stock Theaters (CORST). As a CORST theater company, Saint Michael's Playhouse employs members of Actors' Equity Association, as well as directors from the Stage Directors and Choreographers Society and designers from United Scenic Artists.

The college provides student access to a Saint Michael's-sponsored Culture Pass to the Flynn Center for the Performing Arts.

Clubs and organizations
Saint Michael's offers over 40 different student-run clubs and organizations. Clubs range from the arts (e.g. A cappella groups, Drama Club, Chorale) to community groups (e.g. Common Ground, Food Justice, Student Global AIDS Campaign) to academic clubs (e.g. The Defender, French Club, Onion River Review).

The campus also offers various club sports such as cycling, dance, rugby (men's and women's), ski & snowboarding, ultimate frisbee, and water polo.

Turtle Underground is a student-run program that promotes student art, music, and performance. There are shows on most Saturdays during the semester. These have featured a variety of acts, ranging from DJs to solo singer-songwriters to jam bands.

Student publications include The Defender, a weekly newspaper, and the Onion River Review, a literary magazine.

Adventure Sports Center
The Adventure Sports Center (ASC) at Saint Michael's College features hiking, rock climbing, ice climbing, snowshoeing, kayaking, and skiing. The ASC also offers a season pass to Sugarbush.

Notable alumni and students

 * Moses Anderson 1954, Roman Catholic bishop
 * Tim Arango 1996, Baghdad bureau chief of The New York Times
 * Tom Bowman 1977, National Public Radio's Pentagon reporter
 * Frederick M. "Skip" Burkle Jr 1961, humanitarian assistance and disaster response specialist
 * Tom Caron, host of Boston Red Sox coverage on NESN
 * Donald Cook, United States Marine Corps officer, prisoner of war, and Medal of Honor recipient
 * Thomas W. Costello 1968, Vermont House of Representatives
 * Ann Cummings MSA 1989, mayor of Montpelier, Vermont, and member of the Vermont Senate
 * Rudolph J. Daley (attended), Associate Justice of the Vermont Supreme Court
 * Thomas E. Delahanty II 1967, Maine Superior Court justice
 * Joseph F. Dunford Jr. 1977, 19th Chairman of the Joint Chiefs of Staff and 36th Commandant of the Marine Corps
 * James Fallon 1969, neuroscientist
 * Roger Festa 1972, chemistry professor at Truman State University, former president of the American Institute of Chemists
 * Michael J. Fitzpatrick, New York State Assemblyman representing the 7th district in Suffolk County
 * Tom Freston 1967, former president and CEO of Viacom and one of the founders of MTV
 * Robert Hoehl 1963, co-founder of IDX Systems Corporation
 * Martin Hyun 2003, author, professional ice hockey player with Deutsche Eishockey Liga, 2018 PyeongChang Winter Olympics Deputy Sport Manager
 * Vincent Illuzzi 1975, youngest person ever elected to Vermont State Senate, state senator 1981-2013
 * Brian Kelley, CIA officer
 * George Latimer, DFL mayor of Saint Paul, Minnesota
 * Patrick Leahy 1961, senior U.S. senator from Vermont
 * Bernard Joseph Leddy, former United States federal judge
 * Earle B. McLaughlin (attended), U.S. Marshal for Vermont
 * Robert W. Parker, United States Air Force major general
 * Christina Reiss 1984, federal judge for the United States District Court for the District of Vermont
 * Harold C. Sylvester (attended), judge of the Vermont Superior Court, Associate Justice of the Vermont Supreme Court
 * Richard Tarrant 1965, co-founder of IDX Systems Corporation
 * Michael Tranghese, former commissioner of the Big East Conference
 * Loung Ung 1993, human-rights activist, lecturer, author of First They Killed My Father.
 * Travis Warech (attended; born 1991), American-German-Israeli basketball player for Israeli team Hapoel Be'er Sheva
 * Michael William Warfel G 1990, prelate of the Roman Catholic Church, seventh and current Bishop of Great Falls-Billings.
 * Robert White, president of the Center for International Policy, former US Ambassador to El Salvador and Paraguay

Notable faculty

 * John Engels, professor of English
 * Greg Delanty, professor of English
 * Jim Hefferon, professor of Mathematics

title: Saint Michael's College


text:
Talk:Principle of double effect

Previous discussions: "may also cause an effect one would otherwise be obliged to avoid (sedation and a slightly shortened life)"
 * Archive01: Str1977 12:39, 14 September 2005 (UTC)
 * Note: The above archive mostly consists of writing by User:Famekeeper. —Lowellian (reply) 06:53, 5 October 2005 (UTC)

Why is sedation something one is otherwise obliged to avoid?

Criticism #2
Not a valid criticism. Torture is an 'intrinsic evil,' an inherently bad moral object and therefore the Principle of Double Effect does not even apply. Wikipedia is a joke. —Preceding unsigned comment added by 24.147.25.37 (talk) 18:21, 21 May 2011 (UTC)

Title of article
Should be referred to as "Principle" not "Doctrine". User:194.80.106.135

 * Agreed, and I have moved the page accordingly. Google returns more hits for "principle of double effect" than "doctrine of double effect". —Lowellian (reply) 07:01, 5 October 2005 (UTC)

It should be referred to as the "Doctrine of Double Effect" as that is the term most used in philosophical circles today. It is the term employed by the popular textbook "Ethics in Practice" and the term used by Peter Singer in "Practical Ethics"
 * Doing Ethics also refers to it as the Doctrine of Double Effect Eggbertx (talk) 20:34, 18 October 2010 (UTC)

controversial statements on war
"Whether the Principle applies to the bombing of Hiroshima and Nagasaki is a highly controversial question, whereas the sometimes massive conventional bombing of european cities was usually justify by the principle."

Apart from the obvious spelling mistakes, I don't see where the bombing of European cities were justified by the principle. On the contrary, most history books claim they were of the other type cited in the article, that of purposefully doing wrong to demoralise the enemy. The same was said for the atomic bombs (which, in destruction, were not so much greater than the bombing of Tokyo, for example, or the German cities.) I suggest to rewrite or remove this paragraph. Hoemaco 05:08, 11 September 2007 (UTC)

 * [ Rewritten]. Someone might say "sometimes justified", but it probably applies to both, and this is one of those things that really should be attributed in any case.

some evil must be done to bring about an enormous good?
"Although he is reluctant to give up the bomb's location, his interrogators can exploit his attachment to his family by torturing them before his eyes, in order to extract the information which would save millions of lives."

Imagine a five years old boy screaming while being skinned alive in front of his father. I fail to convince myself that saving other people, even millions, is "enormous good" enough to justify it.
 * Well, yes, but in that case justification would come from the fact that skinning five-year-olds alive is jolly fun! —Preceding unsigned comment added by 83.132.65.97 (talk) 04:01, 4 February 2010 (UTC)

 * I'm not sure that example would fall under double effect anyway - perhaps it should be removed.
 * While torturing a child to extract information from a terrorist father does NOT meet the conditions of the DDE, I think the idea is show that the DDE is too restrictive by presenting an example which "clearly shows" that one may do evil in order to achieve a greater good. If this was the intent, then perhaps some rewording may make this clearer. Then again, DDE implicitly assumes that we already agree that doing evil to achieve good is wrong. Utilitarians who believe that one may murder to harvest organs for many obviously have no need for DDE. 64.42.233.58 21:00, 17 January 2007 (UTC)

 * I don't know how this example can be salvaged. —Preceding unsigned comment added by 192.75.48.150 (talk) 18:12, 11 December 2007 (UTC)

I would like to add that this page has defined very poorly Double-Effect. I studied Thomism and specialized in Aquinas' philosophy at the University of Western Ontario. It is in regard to the third point about conditions on double effect. You state that the two results must be proportionate. This is false, and let me quote Aquinas to prove it

"And yet, though proceeding from a good intention, an act may be rendered unlawful, if it be out of proportion to the end." [Summa Theologica II, II, question 64, article 7]

In other words, proportionality is between the object/act and the intended-result, not between the two ends. If you were to measure proportionality between the two ends you would be rendering the object neutral and therefore be ascribing to a consequentionalistic or utilitarian philosophy. Any more questions e-mail me at cpietra@uwo.ca

Utilitarianism and examples
The article suffers from a serious consistency problem. It says that utilitarians reject DDE and gives torture examples as examples of what is prohibited if the DDE is true. But this doesn't fit the DDE as it is stated at the top of the article. The DDE as given states (I paraphrase for clarity): "IF these four conditions are met, THEN the action is permissible." It does not state that the four conditions MUST be met for an action to be permissible. In fact, a utilitarian can say that the DDE is true, but just doesn't go far enough because you can delete all the conditions except for proportionality. Now as a matter of fact, just about all the ethicists who identify themselves as defenders of the DDE do so because they think it's wrong to intentionally cause basic evils like the death of an innocent person, and yet want to allow tactical bombing or manufacturing vaccines that have rare fatal side-effects. So the self-identified defenders of the DDE do think the conditions are necessary for an action with some basic evils among the consequences to be right. Bu the DDE as stated doesn't say so. So something needs to be fixed in this article. I don't have the time to do this myself.Pruss 22:39, 7 November 2007 (UTC)

 * Yes, I would agree with that. There are certainly many modern deconstructions of the DDE that betray the actual teaching of Thomas Aquinas, such as its use to justify neoconservative agendas of (supposedly) just wars in Iraq and so forth. ADM (talk) 08:33, 18 July 2009 (UTC)

Merging and expanding
I will take up the task of merging the two articles, deleting the temporary one and expanding this one as best as I can. Anyone interested in helping me out with this task will be very welcome. --- Kripkenstein 11:27, 10 February 2006 (UTC)

Citations needed
Citations are needed for (especially) two items. One, the article states: "Double Effect depends on the following principles" and lists three such principles. Where do these come from? Second, in the section "Catholic view", the article lists four requirements for an action to be justified by the doctrine. Perhaps this comes from the Summa Theologica? or the Catholic Encyclopedia? or the New Catholic Encycolpedia? It certainly sounds like the Roman Catholic view, but the article needs to cite the source.

 * The above wasn't me, but I removed the following "The principle of double effect is becoming a defence used by doctors who have acted negligently or illegally in caring for ill or dying patients." because it's a sweeping statement and no citation is given anyway...--212.56.109.125 11:55, 31 May 2006 (UTC)

 * I'm removing the statement "Double Effect depends on the following principles" and the three listed principle; I couldn't find any source that supports it. However, I have inserted the four requirements necessary for the justification of double effect. -- 12:00, 28 Oct 2006

 * Do we need a citation concerning Hiroshima and Nagasaki bombings? Has anyone actually suggested in a published source that the principles of double effect apply to Hiroshima and Nagasaki? The support for Hiroshima bombing seems to take the "ends justifies the means" approach which is distinct from double effect 68.147.171.228 06:16, 8 March 2007 (UTC)
 * The entire article suffers from lack of citations - each example should be cited somewhere, or the point of having examples is lost. Not even Mr. Lister's Koromon survived intact. 07:33, 21 November 2008 (UTC)

Biased content
The last two paragraphs of the "Applications" section are written by an absolutist, who seems to feel that, given current medical knowledge, bad effects can always be avoided. The author refers to (but does not cite) “Thirty years of palliative care experience and research” showing that “it is invariably possible to manage pain or distress with titrated doses of drugs, without hastening death.” This is simply untrue. Current literature suggests that the risk of bad effects, such as dependence and hastening of death, can be reduced but not eliminated entirely (see Fallon M, Hanks G, Cherny N. Principles of control of cancer pain British Medical Journal 2006 Apr 29;332(7548):1022-4 for review). Literature also suggests that pain is often undertreated to avoid adverse effects, constituting a "reverse double effect": allowing pain (intentional bad effect) while avoiding adverse effects. A similar argument follows for the final paragraph. Although neutropenia is an undesirable side effect which warrants careful monitoring and treatment, withholding or reducing chemotherapy to avoid this effect consitutes malpractice, since it allows a primary bad effect (non-treatment of cancer). Both paragraphs should be removed.

I concur --67.114.173.106 19:41, 2 March 2007 (UTC)

I am sympatetic with Claude fight for better information for palliative care. I disagree with carry on a *discussion* on a palliative care article.I very very very disagree with spreading this discussion in many Wikipedia article. Albert0

Oh well, for fear of being more absolutist (I should wish...) I need to point out that the article by Fallon et al has been misrepresented. In this article the authors write: As for hastening death, the authors acknowledge that opioids have that potential, but perhaps I could point you to the section on Opioids which now contains multiple references to the experiences that opioids do not hasten death when used safely.
 * 'Tolerance to opioids is rarely seen in cancer patients.'
 * 'Psychological dependence or addiction is not a problem...'

Perhaps my absolutism on opioids was the reason for removing the second paragraph about neutropaenia, but doing so missed the point. The issue is that many consider it acceptable to link double effect with opioids despite considerable evidence that this does not happen when they are used safely. And yet death due to neutropaenia is never considered as double effect. The point was that death from an opioid should be investigated and analysed in the same way as death from neutropaenia.

I have attempted to correct my absolutism in the changes I made. I promise to try and be less absolute (I think...)

--Claud Regnard 23:53, 4 February 2007 (UTC)

The final sentence of the penultimate paragraph is still biased: "The intent of a palliative care physician is relief without harm, while the second is relief at any cost and suggests either negligence or malice." The intent of "the second" type of physician need not be negligence or malice; if this physician is working under priciples very different from the author's (i.e. if the physician supported assisted suicide in certain cases), she would believe herself to be doing good. A sizeable population of third-party observers would agree.

Good point. However this is not the dilemma it seems as even the Dutch find morphine a poor euthanasia agent and is the drug least used of all in euthansaia in the Netherlands. Therefore, using high doses of morphine is either an negligence or malice. I have altered the text and added a reference to make this clearer. --Claud Regnard 17:43, 19 February 2007 (UTC)

Repetition
The introduction's bullet list is almost exactly the same as the list under the "roman catholic" section--will someone fix this?

You are quite right- in fact I'm not sure why there is a 'Catholic view' since this principle is not a religious edict or instruction. So, apologies to the original author of that section but I have removed it and changed the text describing the principle to a more updated version. --Claud Regnard 17:47, 19 February 2007 (UTC)

War and palliative care
The definition of double effect now includes examples from the military arena. As double effect applies to many different arenas it seems unecessary to include military examples in the definition, especially as 'War' is considered seperately. I have therefore removed military examples from the definition.

Palliative care is being misrepresented by the linkage between pain relief/terminal sedation and euthansia (two quite different clincial approaches). I realise that this has caused disbelief for one contributor earlier this year, but the link to opioids provides more references. Another previous contributor was unhappy that this section on double effect included a discussion about palliative care, but this is inevitable since palliative care is a speciality built around making decisions at the end of life. Consequently, I have altered the text to make this clearer. --Claud Regnard (talk) 21:20, 5 September 2008 (UTC)

Have there been any studies regarding "irresponsible behavior" and "unknown consequences" pertaining to double effect?
Consider the following scenario:

A man who is mentally competent to research explosives and read safety instructions fails to do so out of laziness as he plans to detonate TNT to remove a tree stump from his yard. Had he done the research, he would have known exactly how much TNT to use, but instead uses his best judgment. He uses far too much TNT and the explosion fells a nearby tree into his neighbor's house, killing one or more of its occupants.

Does any part of double effect serve to defend or condemn the man's negligence? Does negligence even get considered in double effect? Certainly other irresponsible behavior, such as driving under the influence or even failing to maintain proper hygine while preparing food for the public is accepted by the majority of the population as unethical and immoral, but according to double effect, the killing or harming of individuals in these cases are merely a side-effect of one's actions. The man with the TNT did not intend to harm anybody, nor did his lack of research directly kill his neighbor. He could have been lucky and had used just the right amount of TNT by chance, or even not enough, in which case it wouldn't have killed anybody, but wouldn't have successfully removed the stump as well. Double effect seems to only pertain to cases where people know all of the options and their consequences, which doesn't apply often in the real world.

Most people would condemn the man responsible for his neighbor's death, as would I, but it seems the principle of double effect would defend this man's actions.

To put this in perspective of an example already in this article, let's assume a strategic target is located right next to an orphanage, and by striking that target, the orphanage is also destroyed, killing the children. Had the generals done more research on the target and discovered this additional information, they would have canceled the strike, but despite their best intentions, they still managed to do just as much harm as if they had struck only the orphanage. Are the generals at fault? Perhaps the answer to this is: if time allowed them to do the extra research, then they are just as responsible for striking the orphanage in this scenario as they would if they knowingly struck the orphanage.

In the case of the trolley killing the man in a hammock, do the ethics involved change if the man was behind a fence and the observer pulling the lever did not know the man was in his hammock, but should have considered this possibility since by pulling the trolley it would be crashing into a fenced-in back yard?

Thoughts?

Randhuck (talk) 18:03, 6 July 2010 (UTC)

Attribution to Aquinas
Should DDE be attributed to Aquinas? G.E.M. Anscombe protests that it shouldn't fairly convincingly in 'Action, Intention and 'Double Effect''. Aquinas's discussion of killing in self defence is not a good guide to his opinion on responsibility for the evil consequences of actions. —Preceding unsigned comment added by 86.26.16.203 (talk) 10:59, 26 November 2010 (UTC)

Medicine
The statements are overly simplified. Public health decisions are heavily based on statistics analysis, i.e., risk of taking the vaccine vs. risk of not taking the vaccine for each individual and scenario. It has nothing to do with "number of people saved vs. number of people killed". Regarding abortion, at least in Western countries, it is not a matter of public health and in the jurisdictions that allow it the decision is an individual one, taken by patients with the advise of practitioners but not enforced by any medical set of standards. Indeed, "the greater evil of the death of both the mother and the fetus" is not a medical definition. The practical consequence is that if the doctor denies the procedure, he or she cannot be prosecuted. Aldo L (talk) 13:10, 24 March 2011 (UTC)

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Who named it "double effect"?
The principle is commonly credited to Aquinas - but who named it "double effect"? Anyone know? SEP doesn't say - David Gerard (talk) 18:34, 27 May 2018 (UTC)

title: Talk:Principle of double effect


text:
Wikipedia talk:Manual of Style/Alpha Archive 3

 * Wikipedia talk:Manual of Style
 * Wikipedia talk:Manual of Style--Archive Directory

New section proposal
I'd like to propose a new section on image/article integration. In particular, I'd like it to be official policy that first image (IE, images at the top of an article) have to go on the right. →Raul654 20:31, Mar 13, 2004 (UTC)

Notes for editors that are visible to non-editors
Some articles contain notes for editors that are visible to non-editors. Most of them are statements of the obvious. They often are merely invites to edits. For example:

 * "A mathematician is a person whose area of study and research is mathematics. [edit] "

 * "Putnam and Saul Kripke both made important contributions to what is known as the causal theory of reference. [Add more here.] "

 * "South African and New Zealand accents have a similar distribution of sounds to Australian. New Zealand accents are more like to use the broad version. Someone who knows them in detail could add more here. [edit] "

 * "The development of algorithms to handle graphs is therefore of major interest in computer science: see graph algorithms. To do: Add more pictures here."

Others are more subtle but still a matter for editors only. For example:

 * "Please use after  for new Tolkien-related articles."

This sort of thing is so common that I think a mention in the manual is needed. Does anyone else dislike it? Bobblewik (talk) 15:22, 27 Aug 2004 (UTC)
 * Yes, I dislike it too and try to remove any instances I find. Some mention of the hidden comments method might be good here. Rmhermen 22:19, Aug 27, 2004 (UTC)

 * I agree that it looks very unprofessional. However if an article is missing crucial aspects I'd rather the reader were made aware of that than think he/she had read a comprehensive assessment of the subject. Is there a curly bracket thing that can be added to the top of partial articles along the lines of or something? adamsan  22:41, 27 Aug 2004 (UTC)
 * AFAIK the only existing equivalent is, which produces  ··gracefool |☺ 14:04, 28 Aug 2004 (UTC)

 * One thing i'm aware of is to mark sections as stubs.  In general notes to editors should be hidden comments, imo.  — siro  χ  o  02:44, Sep 7, 2004 (UTC)

Insertions in edits such as (please insert correct date here) are a last resort, but it's best to keep on editing anyway! These editorial asides are disfiguring but impermanent. It is best to cast doubt on a single dubious statement within the text than to label the entire entry as "disputed," a technique that has become too degraded for some of us to use. These interpolations (in italics please) are also effective, because other editors stop and fix them when we find them. That Wikipedia is a work is progress is the best excuse for Wikipedia's many remaining limping, inadequate entries. We're not ready to be cast in bronze quite yet. Wetman 07:41, 16 Sep 2004 (UTC)

On quotations and punctuation marks
Right now our official policy is to put punctuation marks inside quotation marks if it is a full quotation, but outside the quotation marks if it is a partial quotation. I've been looking at many encyclopedias and found that this is uncommon even in British publications. does anybody else feel that the current policy is needlessly confusing... or am I simply being an Ugly American here? I'd like to change it to have a uniform "punctuation goes inside quotation marks" style, but I really don't want to step on anyone's toes – just looking for a few comments on the issue. ;) [[User:Neutrality|Neutrality (talk)]] 16:52, Sep 19, 2004 (UTC)
 * The present official policy is in agreement with what is done in many (most? all?) other languages. You should consider the fact that many contributors here do not have English as their first language and have in fact learnt in school/university that the punctuation only goes inside the quotation marks if it actually belongs there in the first place. The only reason to do otherwise is, I guess, typographical, and I don't really find it much of an aesthetic improvement to get the empty space in one place rather than in an other./u◦p◦p◦l◦a◦n◦d 17:19, 19 Sep 2004 (UTC)

 * The rule has been in there since the first draft. I believe it is clearer that way.  There were many examples of this usage in the Wikipedia already.  I tried to make the first draft reflect what was already "best practice" in Wikipedia.  Ortolan88 22:21, 19 Sep 2004 (UTC)
 * Personally, I can never remember what the policy is, so I generally just fake it. (I've read enough British authors over the years that my sense of such things is confused. In other words, my gut instinct is unreliable.) There would be something to be said for a system that is entirely consistent (and therefore easier to remember).
 * However, at the moment there is so much inconsistency with regard to punctuation that I almost wonder if it is worth the effort to have a rule. (Trying to enforce any change would be very difficult. Not that the current "rule" is enforced.)--[[User:Aranel|Aranel

("Sarah")]] 22:30, 19 Sep 2004 (UTC)
 * Like the rest of the Manual of Style, none of the rules here are enforced, but when someone who loves copy-editing comes along to tend to an article, maybe quite an old one, they can look in the Manual of Style for guidance on consistency. Not that the rule is all that hard to remember:  If the punctuation is part of what is being quoted, put it inside the quotes, and if it is not part of what is being quoted, leave it out.  That is, the quotation marks contain only what is being quoted.  Ortolan88 22:57, 19 Sep 2004 (UTC)

 * The current Wikipedia policy is often called "logical quotation". I far prefer it, despite what I was taught in school, and always use it when not prevented. Proponents of "typographical quotation" claimed it "looks better". Too often, I believed, it did not look better. It looked stupid. This is especially so in lists of words and meanings. For example, using logical punctuation:
 * "Three French words with related meanings are maison 'house', domaine 'estate, property', and château 'castle'."
 * This seems to be me to be more understandable and better looking than:
 * "Three French words with related meanings are maison 'house,' domaine, 'estate, property,' and château 'castle.'"
 * (The use of single quotation marks here rather than double quotation marks is standard linguistics usage when indicating a meaning of a previous word or phrase regardless of whether in the article as a whole double quotation marks or singlular quotation marks are used for top level quoting. I use it in Wikipedia since I prefer it and guideliness currently don't specify and the convention has spread to technical writing outside of linguistics. But using double quotation marks wouldn't change the point.)
 * Now if you aren't at all concerned with meaning, it is possible that at some level of abstract design that always putting a small base-line punctuation mark before a small high punctuation mark is aesthetically better, if there is an absolute in asethetics. But in parsing a sentence we are concerned with meaning.
 * This is only my personal feeling, not binding on anyone. If the Wikipedia Style Guide specifications had specified typographical quotation, I would bend to its whims. But considering that logical punctuation is specified in prestigious British style guides and in some general technical style guides, it is doubtful that such a rule would have stayed fixed in Wikipedia. The only reasonable choices are between letting the editor choose and logical quotation everywhere.
 * From The Canadian Web Magazine for the Writing Trade: Placement of Punctuation and Quotation Marks:
 * "In a literary work, we recommend the American style of always placing periods and commas inside the quotation marks. In a technical or legal work, where accuracy is essential, we recommend the British practice of placing periods and commas within quotation marks only when they are part of the quoted material."
 * I take Wikipedia as more technical than literary and this recommendation to come from noting increased use of logical punctuation in academic and technical writing outside of Britain.
 * Jallan 00:17, 20 Sep 2004 (UTC)

Various observations: The comma and period inside the quotes "look better" only when true typography is used to place the quote over the punctuation, so that's not really an argument for doing it. My arguments for doing it come from Chicago and many other American style guides, but most acknowledge the historic reasons for the punctuation order. In technical style guides here, it is not the general case for punctuation to go outside the quotes, only when what's inside the quotes is an exact value (as in: type this URL into the field: "http://www.foo.com" .). However, I have no problem using the Wikipedia style guide and editing according to that. Elf | Talk 15:52, 21 Sep 2004 (UTC)


text:
Talk:Osan

50km south of Seoul isn't Gangwon province... Kokiri 11:26, 25 Aug 2004 (UTC)

 * Yes, it's about 35 km. I fixed the distance, fleshed out the table, and removed the cleanup tag...  I'm darn near my 5000th edit now!  -Sewing - talk

Hanja
What does "Osan" mean in hanja?
 * Thereby hangs an interesting tale, which I have added to the article. If any one can find a more authoritative source, that would be excellent. -- Visviva 14:09, 23 March 2006 (UTC)

Location map?
With due respect, indicating the location of Osan by using which appears to be a provincial/district outline map is of no use to a person not knowledgeable of the geography of the RoK. I can figure out that it somewhere on the west coast of Rok. Possibly located near the Yellow Sea. Could somebody link a South Korean or Korean Peninsula map which would give a reference. See the Daegu page for reference. Thanks! --TGC55 (talk) 15:31, 27 May 2008 (UTC)

title: Talk:Osan


text:
Tunnel diode

A tunnel diode or Esaki diode is a type of semiconductor diode that has effectively "negative resistance" due to the quantum mechanical effect called tunneling. It was invented in August 1957 by Leo Esaki and Yuriko Kurose when working at Tokyo Tsushin Kogyo, now known as Sony. In 1973, Esaki received the Nobel Prize in Physics for experimental demonstration of the electron tunneling effect in semiconductors. Robert Noyce independently devised the idea of a tunnel diode while working for William Shockley, but was discouraged from pursuing it. Tunnel diodes were first manufactured by Sony in 1957, followed by General Electric and other companies from about 1960, and are still made in low volume today.

Tunnel diodes have a heavily doped positive-to-negative (P-N) junction that is about 10 nm (100 Å) wide. The heavy doping results in a broken band gap, where conduction band electron states on the N-side are more or less aligned with valence band hole states on the P-side. They are usually made from germanium, but can also be made from gallium arsenide, gallium antimonide (GaSb) and silicon materials.

Uses
The negative differential resistance in part of their operating range allows them to function as oscillators and amplifiers, and in switching circuits using hysteresis. They are also used as frequency converters and detectors. Their low capacitance allows them to function at microwave frequencies, far above the range of ordinary diodes and transistors.

Due to their low output power, tunnel diodes are not widely used: Their radio frequency output is limited to a few hundred milliwatts due to their small voltage swing. In recent years, however, new devices that use the tunneling mechanism have been developed. The resonant-tunneling diode (RTD) has achieved some of the highest frequencies of any solid-state oscillator.

Another type of tunnel diode is a metal-insulator-insulator-metal (MIIM) diode, where an additional insulator layer allows "step tunneling" for more precise control of the diode. There is also a metal-insulator-metal (MIM) diode, but due to inherent sensitivities, its present application appears to be limited to research environments.

Forward bias operation
Under normal forward bias operation, as voltage begins to increase, electrons at first tunnel through the very narrow P-N junction barrier and fill electron states in the conduction band on the N-side which become aligned with empty valence band hole states on the P-side of the P-N junction. As voltage increases further, these states become increasingly misaligned, and the current drops. This is called negative differential resistance because current decreases with increasing voltage. As voltage increases beyond a fixed transition point, the diode begins to operate as a normal diode, where electrons travel by conduction across the P-N junction, and no longer by tunneling through the P–N junction barrier. The most important operating region for a tunnel diode is the "negative resistance" region. Its graph is different from normal P-N junction diode.

Reverse bias operation
When used in the reverse direction, tunnel diodes are called back diodes (or backward diodes) and can act as fast rectifiers with zero offset voltage and extreme linearity for power signals (they have an accurate square law characteristic in the reverse direction). Under reverse bias, filled states on the P-side become increasingly aligned with empty states on the N-side, and electrons now tunnel through the P-N junction barrier in reverse direction.

Technical comparisons
In a conventional semiconductor diode, conduction takes place while the P-N junction is forward biased and blocks current flow when the junction is reverse biased. This occurs up to a point known as the "reverse breakdown voltage" at which point conduction begins (often accompanied by destruction of the device). In the tunnel diode, the dopant concentrations in the P and N layers are increased to a level such that the reverse breakdown voltage becomes zero and the diode conducts in the reverse direction. However, when forward-biased, an effect occurs called quantum mechanical tunneling which gives rise to a region in its voltage vs. current behavior where an increase in forward voltage is accompanied by a decrease in forward current. This "negative resistance" region can be exploited in a solid state version of the dynatron oscillator which normally uses a tetrode thermionic valve (vacuum tube).

Applications
The tunnel diode showed great promise as an oscillator and high-frequency threshold (trigger) device since it operated at frequencies far greater than the tetrode could: well into the microwave bands. Applications of tunnel diodes included local oscillators for UHF television tuners, trigger circuits in oscilloscopes, high-speed counter circuits, and very fast-rise time pulse generator circuits. In 1977, the Intelsat V satellite receiver used a microstrip tunnel diode amplifier (TDA) front-end in the 14–15.5 GHz frequency band. Such amplifiers were considered state-of-the-art, with better performance at high frequencies than any transistor-based front end. The tunnel diode can also be used as a low-noise microwave amplifier. Since its discovery, more conventional semiconductor devices have surpassed its performance using conventional oscillator techniques. For many purposes, a three-terminal device, such as a field-effect transistor, is more flexible than a device with only two terminals. Practical tunnel diodes operate at a few milliamperes and a few tenths of a volt, making them low-power devices. The Gunn diode has similar high frequency capability and can handle more power.

Tunnel diodes are also more resistant to ionizing radiation than other diodes. This makes them well suited to higher radiation environments such as those found in space.

Longevity
Tunnel diodes are susceptible to damage by overheating, and thus special care is needed when soldering them.

Tunnel diodes are notable for their longevity, with devices made in the 1960s still functioning. Writing in Nature, Esaki and coauthors state that semiconductor devices in general are extremely stable, and suggest that their shelf life should be "infinite" if kept at room temperature. They go on to report that a small-scale test of 50 year-old devices revealed a "gratifying confirmation of the diode's longevity". As noticed on some samples of Esaki diodes, the gold-plated iron pins can in fact corrode and short out to the case. This can usually be diagnosed and treated with simple peroxide / vinegar technique normally used for repairing phone PCBs and the diode inside normally still works.

Surplus Russian components are also reliable and often can be purchased for a few pence, despite original cost being in the £30–50 range. The units typically sold are GaAs based and have a $I$ ratio of 5:1 at around 1–20 mA $V$pk, and so should be protected against overcurrent.

title: Tunnel diode