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Talk:Montreal Protocol

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Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 04:26, 17 January 2022 (UTC)

Developing countries
I have been told that the protocol allows 'developing countries' to continue producing the banned CFCs. I'm wondering what countries are defined as 'developing' for this purpose. Any ideas?

-- Yes. "Developing countries" is used here as a technical short-hand for those countries the Parties refer to as "Article 5 countries." Article 5 countries have limited production of ozone-depleting substances, and are in some sense self-defined, but generally fall beneath certain thresholds for low income and development. The list of countries corresponds very closely to the general understanding.

Developing countries must also phase out the listed ozone-depleting substances, but they are on a longer time-frame for the phaseout.

Take a look at link UNEP's Article 5 Parties. Most countries on the list would be regarded as developing by most people, but the are some that many people would regard as developed. The IMF regards Singapore as an advanced economy and the World Bank classifies Antigua & Barbuda, Bahamas, Bahrain, Barbados, Brunei Darussalam, Equatorial Guinea, Kuwait, Oman, Qatar, Saudi Arabia, Singapore, Trinidad and Tobago and the United Arab Emirates as high income countries. David Sturt (talk) 13:32, 27 December 2008 (UTC)

WP:RM
Discussion on renaming page, from WP:RM

Montreal Protocol on Substances that Deplete the Ozone Layer → Montreal Protocol -- The Kyoto Protocol is set up with its common short name, instead of Kyoto Protocol to the United Nations Framework Convention on Climate Change, whereas the almost as common Montreal Protocol is not... (or you can reverse this argument and move Kyoto Protocol to its proper name) 132.205.15.4 19:46, 23 Oct 2004 (UTC)
 * No opinion - William M. Connolley 20:39, 23 Oct 2004 (UTC).
 * Definitely should both be the same, and I suspect the shorter name is the way to go (in line with Naming conventions (common names), wnich ways we're supposed to use "the most common name of a person or thing"). Noel 18:27, 24 Oct 2004 (UTC)

Binding?
Is this a "binding" agreement? If so, what are the signatories required to do? What has been the U.S. response to the treaty? What has the EPA done to enforce the treaty? -- User:Ed Poor

-- Yes. The treaty is binding for Parties. Parties have a wide range of responsibilities, the most important of which is the phasing out of the production and use of certain ozone-depleting substances. The U.S. EPA has promulgated a wide range of regulations to enforce the treaty, largely pursuant to its authority under the U.S. Clean Air Act.

Moving the reasons
I am planning to move all the reasons for the protocol to this page. I will leave behind on the relevant pages links to the following argument:
 * 1) CFC emissions reduce statospheric ozone
 * 2) Reduced ozoze increases surface UV
 * 3) Increased surface UV increase skin cancer

I will put all the evidence which supports this hypothesis here, as well as evidence that fails to support the hypothesis. Readers can make up their own mind as to whether the facts support the hypothesis.

 * The relevant pages (CFC, Ozone depletion, Ultraviolet) are just fine and don't need to be changed. You can easily add the rationale behind the protocol to this article by pointing to the other articles. If somebody wants to know why UV causes cancer, they certainly would not (and should not!) look under "Montreal protocol". AxelBoldt

-- I agree. Links are more appropriate. This page would be most useful to readers if it stays focused on the Protocol itself.

CFC Ban
The article CFC ban is listed to be merged with this article. It seems to be all here except the following: Other bans have been made or proposed based on incomplete or disputed science (see precautionary principle). I'm not sure this material belongs here. I'm going to make CFC ban a redirect to here. If anyone thinks the above line (and its list of articles) belongs here they can merge it in (see the history of that article if interested). RJFJR 03:51, Apr 2, 2005 (UTC)

When?
When was the Protocol negotiated? How long did it take? Any interesting diplomacy to discuss? RJFJR 03:44, Apr 2, 2005 (UTC)

Strawberry fields forever ozone depleting in america
This is the same america that did Agent Orange:

http://www.cnn.com/2005/TECH/science/11/28/pesticide.politics.ap/index.html

HCFCs
I will try to add something in the text about HCFCs, please correct me if I was to bold ;-) --Bbold 17:05, 26 April 2006 (UTC)

Scientific Background
Changed "recent" to "contemporary" in the first paragraph. "Recent" is always related to the present and so didn't seem to make sense.Schaddm 04:03, 14 September 2006 (UTC)

Vienna Amendment
Pardon my forward comment, but I am unaware of a Vienna Amendment signed in 1995, only the Vienna Convention which was initiated in 1985. Is this correct? The basis for my comment is a research paper produced by the national environmental ministry in South Africa. Please provide clarity. Y Naiker 08:34, 12 July 2007 (UTC) hay naku bakit niyo yan pinag uusapan h8huhuhuhuhuhuhuhuh mabuti la na ung mga HCFC HFC HC AT CFC —Preceding unsigned comment added by 58.69.96.37 (talk) 11:41, 3 August 2009 (UTC)

Yesterday, Wednesday, the fifth,
Paul Ralph Ehrlich, George Shultz,  Amy Goodman, < http://auroraforum.stanford.edu/events.php?id=47 >, discussed   Montr%c3%a9al Protocol,  Kyoto Protocol,  global warming,  Iraq,... et cetera, @  Stanford.

[[ hopiakuta Please do  sign  your  signature  on your  message. %7e%7e  Thank You. -]] 15:30, 6 September 2007 (UTC)

Name
it's odd that this article gives no indication of why it is called the Montreal protocol. I'm assuming it was negotiated there? - TheMightyQuill (talk) 21:01, 26 February 2008 (UTC)

See

 * I still see no evidence that CFC's can get "up" into the ozone layer to cause damage. These molecules are very dense.  I've see a quick puff of R-12 snuff a smoldeering cigarette butt 10 feet away in about 30 seconds.  This substanse creeps along the ground, even high heat cannot make it get higher in the atmosphere than hydrogen could. 68.231.189.202 (talk) 19:47, 18 March 2008 (UTC)

CFC Inhalers / Evohalers
Just wondering about the section referring to inhalers being critical use and still allowed; I heard that evohalers or something of the kind were being produced, and thus old style inhalers were being phased out. http://www.prnewswire.co.uk/cgi/news/release?id=195940 + http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=2222599 - I know personally I'm using a salbutumol evohaler atm, so just thought I'd look for quick sources and post a note, may correct if I have more time or a more informed response.~Cortal YX Talk? 23:44, 11 April 2008 (UTC)

UN Member State Ratification
The article says that 195/196 UN member states have ratified the Protocol. However, there are only 192 member states (according to United Nations). Should it say 191 of 192? —Preceding unsigned comment added by 128.135.208.186 (talk) 17:29, 16 September 2009 (UTC)

Usage of "State"
State is the most correct word to use referring to the entities that have ratified the Montreal Protocol. However, it may be confusing to some US readers, who tend to use 'state' mostly for referring to parts of the USA. Is there a policy or consensus on the usage of 'state' vs. 'country' vs. 'nation'? Eric Wes Brown (Talk) 23:43, 13 September 2010 (UTC)

0.3 kg ?????? looks like a data error
"The main objective of the Multilateral Fund for the Implementation of the Montreal Protocol is to assist developing country parties to the Montreal Protocol whose annual per capita consumption and production of ozone depleting substances (ODS) is less than 0.3 kg to comply with the control measures of the Protocol." ---this is why references would be useful... appears to be a mistake that calls into question the whole sentence..........

Avram Primack (talk) 04:00, 19 November 2011 (UTC)

I believe the text is correct: 0.3kg consumption per capita, as found here: https://ozone.unep.org/treaties/montreal-protocol/articles/article-5-special-situation-developing-countries

The definition of "consumption" can be found in Article 1: ""Consumption" means production plus imports minus exports of controlled substances." https://ozone.unep.org/treaties/montreal-protocol/articles/article-1-definitions

One nuance is the following situation: suppose that 1 kg of a banned substance is produced in country A and filled into a refrigerator which is then exported to country B. I believe this still counts against country A, but I can't find a source.

Flinker123 (talk) 05:23, 5 February 2020 (UTC)

Missing what was banned and when
Article has only the barest description of what got banned and what got used to replace it. Also, no description of the aspects of the treaty that make it equitable or why it needed to be equitable. Someone should add this material, as most of the value of the article could be in this material. What is there is very formalized and cryptic.

Avram Primack (talk) 05:09, 19 November 2011 (UTC)

This reference does not exist at the listed address
"Source - http://www.epa.gov/history/topics/montreal/01.ht" Since the reference does not exist, the section has no verifiable source. It should have. Avram Primack (talk) 05:30, 19 November 2011 (UTC)

Missing Reference
BTW, I attended an Ecology lecture at ASU (PhD in Biology plus post-doctoral study of Ecology) in 1990 where I learned that chlorine in the stratosphere takes from 75 - 115 years (depending on the CFC chemical tranport) before it stops grabbing ozone ions split via UV radiation allowing the oxygen ions to re-combine to form another ozone molecule. If we stopped today, there'd still be another 100 years of depletion ahead of us; we won't stop today. But I digress.

I can't find the "Roan, p56" reference. I corrected the link to the Chaffee Memorial Lecture, http://www.ncseonline.org/sites/default/files/ChafeeMemorialLecture2000.pdf, but that's only 52 pages, so "Roan" couldn't be a mis-spelling of Rowland. I earned my Masters at UC Irvine, then was employed there as a director of computer labs, thus my interest in a letter to the Chancellor complaining about Rowland's public statements. Sew! where's the letter? I grepped Roan on the article source, found only once at the end of the Abplanalp sentence. The wiki/Abplanalp contains only his obituaries, labeled a stub.

Why isn't the interview archived at http://www.vega.org.uk/video/programme/119 mentioned?

Although the Clean Air Act Amendments of 1990 may seem like a smart idea, Congress has yet to provide sufficient funds for enforcement. Count the field agents over at EPA. But I digress. --- Wow, I entered "abplanalp uc irvine chancellor letter" at https://duckduckgo.com/ (my new favorite search engine) and turned up half a dozen hits containing the same paragraph as that published herein. The correct citation is: Roan, Sharon (1990). Ozone Crisis, the 15 Year Evolution of a Sudden Global Emergency. Wiley. ISBN 0-471-52823-4. I may have to retract my criticism of the missing reference, that is, if Amazon has a used paperback copy of the book. Maybe http://archive.org has a copy. I'm amazed at how one sentence gets propagated all over the place, from Websters dictionary entry on "ozone", the Full Wiki and http://www.historyofinformation.com (self-reference?).

Hpfeil (talk) 19:09, 7 March 2012 (UTC)

The two ozone treaties have been ratified by 197 states and the European Union
Why group the EU when they are separate states? — Preceding unsigned comment added by 184.161.42.156 (talk) 22:01, 15 November 2013 (UTC)

Terms and purposes section Comment
I attempted to point to a name instead of just a reference but made an error. I was also reviewing the reference and was putting the access date. Apparently I need to work on using this system as it only produced a reference error so I self reverted. Under the old way I could simply use a name as a clickable link that I think would look better but this would be mixing reference styles.
 * See: EPA Ozone depleting substance table. Otr500 (talk) 12:10, 2 July 2015 (UTC)

External links modified
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External links modified (January 2018)
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"molecule-for-molecule basis" ?
The article currently contains the following sentence: "On a molecule-for-molecule basis, these compounds are up to 10,000 times more potent greenhouse gases than carbon dioxide". I believe this is wrong. Everything I've seen about the climate impact of these compounds is on a per-weight basis, not per-molecule. See for example the page on Global Warming Potential: https://en.wikipedia.org/wiki/Global_warming_potential

Does anyone have a reason to believe the sentence is correct?

Flinker123 (talk) 05:28, 5 February 2020 (UTC)

Ronald Reagan had skin cancer in 1985
What Convinced Ronald Reagan to Take Action on Ozone Hole Time, 2019.

THE HOLE How Ronnie and Maggie Saved the World
https://www.youtube.com/watch?v=M2JzOlRff08 narrated by David Attenborough probably deserves a mention either in this article or in Ozone depletion or both. It's notable IMO and should be covered somewhere in Wikipedia, at least as further reading (viewing?). Comments? Andrewa (talk) 04:49, 17 March 2022 (UTC)

Which treaty?
The Montreal Protocol is a protocol to a treaty - which treaty? Alanthehat (talk) 11:56, 18 July 2022 (UTC)

Wiki Education assignment: Plant Ecology Winter 2023
— Assignment last updated by Briannabanana0 (talk) 02:08, 24 February 2023 (UTC)

Nitrous Oxide speculation is misplaced
The speculative content about Nitrous Oxide as a candidate for inclusion in the Montreal Protocol is probably misplaced. The primary anthropogenic sources of nitrous oxide in the upper atmosphere are agricultural fertilizer and animal waste in the tropics. NB: animal in the biological sense includes reptiles, birds, fish, shellfish, insects, krill, zooplankton… This would have to be addressed by changes in the same developing nations whose commitment to reducing CFC and HCFC production doesn’t take effect until the 2040’s. Ending anthropomorphic generation of NO2 in the developed nations that have already ended CFC production would change the amount transported into the upper atmosphere by -5%, much less than the variation in the rate it is destroyed by sunlight, and result in an unmeasurable -0.25% change in the 0.38ppb/year change in concentration. A mandate that would have the effect of reducing the food supply by 60%-80% and raising its cost 2.5x to 5x that can’t produce a measurable effect is impossible for any national government to agree to without being driven from power. Mercifully the model shows 94% feedback on the rate of destruction, i.e. it reaches a steady state value that attenuates the effect of a change in the rate of production by more than 20:1. PolychromePlatypus (talk) 00:00, 12 July 2024 (UTC)

title: Talk:Montreal Protocol


text:
Neutron bomb

A neutron bomb, officially defined as a type of enhanced radiation weapon (ERW), is a low-yield thermonuclear weapon designed to maximize lethal neutron radiation in the immediate vicinity of the blast while minimizing the physical power of the blast itself. The neutron release generated by a nuclear fusion reaction is intentionally allowed to escape the weapon, rather than being absorbed by its other components. The neutron burst, which is used as the primary destructive action of the warhead, is able to penetrate enemy armor more effectively than a conventional warhead, thus making it more lethal as a tactical weapon.

The concept was originally developed by the United States in the late 1950s and early 1960s. It was seen as a "cleaner" bomb for use against massed Soviet armored divisions. As these would be used over allied nations, notably West Germany, the reduced blast damage was seen as an important advantage.

ERWs were first operationally deployed for anti-ballistic missiles (ABMs). In this role, the burst of neutrons would cause nearby warheads to undergo partial fission, preventing them from exploding properly. For this to work, the ABM would have to explode within approximately 100 m of its target. The first example of such a system was the W66, used on the Sprint missile used in the US Nike-X system. It is believed the Soviet equivalent, the A-135's 53T6 missile, uses a similar design.

The weapon was once again proposed for tactical use by the United States in the 1970s and 1980s, and production of the W70 began for the MGM-52 Lance in 1981. This time, it led to protests as the growing anti-nuclear movement gained strength through this period. Opposition was so intense that European leaders refused to accept it on their territory. US President Ronald Reagan ordered the production of the W70-3, which remained in the US stockpile until they were retired in 1992. The last W70 was dismantled in February 1996.

Basic concept
In a standard thermonuclear design, a small fission bomb is placed close to a larger mass of thermonuclear fuel, usually lithium deuteride. The two components are then placed within a thick radiation case, usually made from uranium, lead, or steel. The case traps the energy from the fission bomb for a brief period, allowing it to heat and compress the main thermonuclear fuel. The case is normally made of depleted uranium or natural uranium metal, because the thermonuclear reactions give off extraordinarily large numbers of high-energy neutrons that can cause fission reactions in the casing material. These can add considerable energy to the reaction; in a typical design, as much as 50% of the total energy comes from fission events in the casing. For this reason, these weapons are technically known as fission-fusion-fission designs.

In a neutron bomb, the casing material is selected either to be transparent to neutrons or to actively enhance their production. The burst of neutrons created in the thermonuclear reaction is then free to escape the bomb, outpacing the physical explosion. By designing the thermonuclear stage of the weapon carefully, the neutron burst can be maximized while minimizing the blast itself. This makes the lethal radius of the neutron burst greater than that of the explosion itself. Since the neutrons are absorbed or decay rapidly, such a burst over an enemy column would kill the crews but leave the area able to be quickly reoccupied.

Compared to a pure fission bomb with an identical explosive yield, a neutron bomb would emit about ten times the amount of neutron radiation. In a fission bomb, at sea level, the total radiation pulse energy which is composed of both gamma rays and neutrons is approximately 5% of the entire energy released; in neutron bombs, it would be closer to 40%, with the percentage increase coming from the higher production of neutrons. Furthermore, the neutrons emitted by a neutron bomb have a much higher average energy level (close to 14 MeV) than those released during a fission reaction (1–2 MeV).

Technically speaking, every low-yield nuclear weapon is a radiation weapon, including non-enhanced variants. All nuclear weapons up to about 10 kilotons in yield have prompt neutron radiation as their furthest-reaching lethal component. For standard weapons above about 10 kilotons of yield, the lethal blast and thermal effects radius begins to exceed the lethal ionizing radiation radius. Enhanced radiation weapons also fall into this same yield range and simply enhance the intensity and range of the neutron dose for a given yield.

History and deployment to present
The conception of neutron bombs is generally credited to Samuel T. Cohen of the Lawrence Livermore National Laboratory, who developed the concept in 1958. Initial development was carried out as part of projects Dove and Starling, and an early device was tested underground in early 1962. Designs for a "weaponized" version were developed in 1963.

Development of two production designs for the Army's MGM-52 Lance short-range missile began in July 1964, the W63 at Livermore and the W64 at Los Alamos. Both entered phase three testing in July 1964, and the W64 was cancelled in favor of the W63 in September 1964. The W63 was in turn cancelled in November 1965 in favor of the W70 (Mod 0), a conventional design. By this time, the same concepts were being used to develop warheads for the Sprint missile, an anti-ballistic missile (ABM), with Livermore designing the W65 and Los Alamos the W66. Both entered phase three testing in October 1965, but the W65 was cancelled in favor of the W66 in November 1968. Testing of the W66 was carried out in the late 1960s, and it entered production in June 1974, the first neutron bomb to do so. Approximately 120 were built, with about 70 of these being on active duty during 1975 and 1976 as part of the Safeguard Program. When that program was shut down they were placed in storage, and eventually decommissioned in the early 1980s.

Development of ER warheads for Lance continued, but in the early 1970s, attention had turned to using modified versions of the W70, the W70 Mod 3. Development was subsequently postponed by President Jimmy Carter in 1978 following protests against his administration's plans to deploy neutron warheads to ground forces in Europe. On November 17, 1978, in a test, the USSR detonated its first similar-type bomb. President Ronald Reagan restarted production in 1981. The Soviet Union renewed a propaganda campaign against the US's neutron bomb in 1981 following Reagan's announcement. In 1983, Reagan then announced the Strategic Defense Initiative, which surpassed neutron bomb production in ambition and vision and with that, neutron bombs quickly faded from the center of the public's attention.

Three types of enhanced radiation weapons (ERW) were deployed by the United States. The W66 warhead, for the anti-ICBM Sprint missile system, was deployed in 1975 and retired the next year, along with the missile system. The W70 Mod 3 warhead was developed for the short-range, tactical MGM-52 Lance missile, and the W79 Mod 0 was developed for nuclear artillery shells. The latter two types were retired by President George H. W. Bush in 1992, following the end of the Cold War. The last W70 Mod 3 warhead was dismantled in 1996, and the last W79 Mod 0 was dismantled by 2003, when the dismantling of all W79 variants was completed.

According to the Cox Report, as of 1999, the United States had never deployed a neutron weapon. The nature of this statement is not clear; it reads, "The stolen information also includes classified design information for an enhanced radiation weapon (commonly known as the "neutron bomb"), which neither the United States, nor any other nation, has ever deployed." However, the fact that neutron bombs had been produced by the US was well known at this time and part of the public record. Cohen suggests the report is playing with the definitions; while the US bombs were never deployed to Europe, they remained stockpiled in the US.

In addition to the two superpowers, France and China are known to have tested neutron or enhanced radiation bombs. France conducted an early test of the technology in 1967 and tested an "actual" neutron bomb in 1980. China conducted a successful test of neutron bomb principles in 1984 and a successful test of a neutron bomb in 1988. However, neither of those countries chose to deploy neutron bombs. Chinese nuclear scientists stated before the 1988 test that China had no need for neutron bombs, but it was developed to serve as a "technology reserve", in case the need arose in the future.

In May 1998, Senior Pakistani Scientist, Dr. N. M. Butt, stated that "PAEC built a sufficient number of neutron bombs—a battlefield weapon that is essentially a low yield device".

In August 1999, the Indian government stated that India was capable of producing a neutron bomb.

Although no country is currently known to deploy them in an offensive manner, all thermonuclear dial-a-yield warheads that have about 10 kiloton and lower as one dial option, with a considerable fraction of that yield derived from fusion reactions, can be considered able to be neutron bombs in use, if not in name. The only country definitely known to deploy dedicated (that is, not dial-a-yield) neutron warheads for any length of time is the Soviet Union/Russia, which inherited the USSR's neutron warhead equipped ABM-3 Gazelle missile program. This ABM system contains at least 68 neutron warheads with a 10-kiloton yield each and it has been in service since 1995, with inert missile testing approximately every other year since then (2014). The system is designed to destroy incoming endoatmospheric nuclear warheads aimed at Moscow and other targets and is the lower-tier/last umbrella of the A-135 anti-ballistic missile system (NATO reporting name: ABM-3).

By 1984, according to Mordechai Vanunu, Israel was mass-producing neutron bombs.

Considerable controversy arose in the US and Western Europe following a June 1977 Washington Post exposé describing US government plans to equip US Armed Forces with neutron bombs. The article focused on the fact that it was the first weapon specifically intended to kill humans with radiation. Lawrence Livermore National Laboratory director Harold Brown and Soviet General Secretary Leonid Brezhnev both described neutron bombs as a "capitalist bomb", because it was designed to destroy people while preserving property.

Use

Neutron bombs are purposely designed with explosive yields lower than other nuclear weapons. Since neutrons are scattered and absorbed by air, neutron radiation effects drop off rapidly with distance in air. As such, there is a sharper distinction, relative to thermal effects, between areas of high lethality and areas with minimal radiation doses. No high yield (more than c. 10 kiloton) nuclear bombs, including the extreme example of the 50 megaton Tsar Bomba, are able to radiate sufficient neutrons beyond their lethal blast range when detonated as a surface burst or low altitude air burst and so are not classified as neutron bombs, thus limiting the yield of neutron bombs to a maximum of about 10 kilotons. The intense pulse of high-energy neutrons generated by a neutron bomb is the principal killing mechanism, not the fallout, heat or blast.

The inventor of the neutron bomb, Sam Cohen, criticized the description of the W70 as a neutron bomb since it could be configured to yield 100 kilotons:

"the W-70 ... is not even remotely a 'neutron bomb.' Instead of being the type of weapon that, in the popular mind, 'kills people and spares buildings' it is one that both kills and physically destroys on a massive scale. The W-70 is not a discriminate weapon, like the neutron bomb—which, incidentally, should be considered a weapon that 'kills enemy personnel while sparing the physical fabric of the attacked populace, and even the populace too.'"

Although neutron bombs are commonly believed to "leave the infrastructure intact", with current designs that have explosive yields in the low kiloton range, detonation in (or above) a built-up area would still cause a sizable degree of building destruction, through blast and heat effects out to a moderate radius, albeit considerably less destruction, than when compared to a standard nuclear bomb of the exact same total energy release or "yield".

The Warsaw Pact tank strength was over twice that of NATO, and Soviet deep battle doctrine was likely to be to use this numerical advantage to rapidly sweep across continental Europe if the Cold War ever turned hot. Any weapon that could break up their intended mass tank formation deployments and force them to deploy their tanks in a thinner, more easily dividable manner, would aid ground forces in the task of hunting down solitary tanks and using anti-tank missiles against them, such as the contemporary M47 Dragon and BGM-71 TOW missiles, of which NATO had hundreds of thousands.

Rather than making extensive preparations for battlefield nuclear combat in Central Europe, the Soviet military leadership believed that conventional superiority provided the Warsaw Pact with the means to approximate the effects of nuclear weapons and achieve victory in Europe without resort to those weapons.

Neutron bombs, or more precisely, enhanced [neutron] radiation weapons were also to find use as strategic anti-ballistic missile weapons, and in this role, they are believed to remain in active service within Russia's Gazelle missile.

Effects

Upon detonation, a near-ground airburst of a 1-kiloton neutron bomb would produce a large blast wave and a powerful pulse of both thermal radiation and ionizing radiation in the form of fast (14.1   MeV) neutrons. The thermal pulse would cause third degree burns to unprotected skin out to approximately 500 meters. The blast would create pressures of at least 4.6   psi (32 kPa) out to a radius of 600 meters, which would severely damage all non-reinforced concrete structures. At the conventional effective combat range against modern main battle tanks and armored personnel carriers (<   690–900    m), the blast from a 1    kt neutron bomb would destroy or damage to the point of nonusability almost all un-reinforced civilian buildings.

Using neutron bombs to stop an enemy armored attack by rapidly incapacitating crews with a dose of 80+ Gy of radiation would require exploding large numbers of them to blanket the enemy forces, destroying all normal civilian buildings within c.   600 meters of the immediate area. Neutron activation from the explosions could make many building materials in the city radioactive, such as galvanized steel (see area denial use below).

Because liquid-filled objects like the human body are resistant to gross overpressure, the 4–5   psi (28-34 kPa) blast overpressure would cause very few direct casualties at a range of c.    600    m. The powerful winds produced by this overpressure, however, could throw bodies into objects or throw debris at high velocity, including window glass, both with potentially lethal results. Casualties would be highly variable depending on surroundings, including potential building collapses.

The pulse of neutron radiation would cause immediate and permanent incapacitation to unprotected outdoor humans in the open out to 900 meters, with death occurring in one or two days. The median lethal dose (LD50) of 6 Gray would extend to between 1350 and 1400 meters for those unprotected and outdoors, where approximately half of those exposed would die of radiation sickness after several weeks.

A human residing within, or simply shielded by, at least one concrete building with walls and ceilings 30 cm thick, or alternatively of damp soil 24 inches (60 cm) thick, would receive a neutron radiation exposure reduced by a factor of 10. Even near ground zero, basement sheltering or buildings with similar radiation shielding characteristics would drastically reduce the radiation dose.

Furthermore, the neutron absorption spectrum of air is disputed by some authorities, and depends in part on absorption by hydrogen from water vapor. Thus, absorption might vary exponentially with humidity, making neutron bombs far more deadly in desert climates than in humid ones.

Effectiveness in modern anti-tank role

The questionable effectiveness of ER weapons against modern tanks is cited as one of the main reasons that these weapons are no longer fielded or stockpiled. With the increase in average tank armor thickness since the first ER weapons were fielded, it was argued in the March 13, 1986, New Scientist magazine that tank armor protection was approaching the level where tank crews would be almost fully protected from radiation effects. Thus, for an ER weapon to incapacitate a modern tank crew through irradiation, the weapon must be detonated at such proximity to the tank that the nuclear explosion's blast would now be equally effective at incapacitating it and its crew.

However, although the author did note that effective neutron absorbers and neutron poisons such as boron carbide can be incorporated into conventional armor and strap-on neutron moderating hydrogenous material (substances containing hydrogen atoms), such as explosive reactive armor, increasing the protection factor, the author holds that in practice, combined with neutron scattering, the actual average total tank area protection factor is rarely higher than 15.5 to 35. According to the Federation of American Scientists, the neutron protection factor of a "tank" can be as low as 2, without qualifying whether the statement implies a light tank, medium tank, or main battle tank.

A composite high-density concrete, or alternatively, a laminated graded-Z shield, 24 units thick of which 16 units are iron and 8 units are polyethylene containing boron (BPE), and additional mass behind it to attenuate neutron capture gamma rays, is more effective than just 24 units of pure iron or BPE alone, due to the advantages of both iron and BPE in combination. During neutron transport, iron is effective in slowing down/scattering high-energy neutrons in the 14-MeV energy range and attenuating gamma rays, while the hydrogen in polyethylene is effective in slowing down these now slower fast neutrons in the few MeV range, and boron 10 has a high absorption cross section for thermal neutrons and a low production yield of gamma rays when it absorbs a neutron. The Soviet T-72 tank, in response to the neutron bomb threat, is cited as having fitted a boronated polyethylene liner, which has had its neutron shielding properties simulated.

However, some tank armor material contains depleted uranium (DU), common in the US's M1A1 Abrams tank, which incorporates steel-encased depleted uranium armor, a substance that will fast fission when it captures a fast, fusion-generated neutron, and thus on fissioning will produce fission neutrons and fission products embedded within the armor, products which emit, among other things, penetrating gamma rays. Although the neutrons emitted by the neutron bomb may not penetrate to the tank crew in lethal quantities, the fast fission of DU within the armor could still ensure a lethal environment for the crew and maintenance personnel by fission neutron and gamma ray exposure, largely depending on the exact thickness and elemental composition of the armor—information usually hard to attain. Despite this, Ducrete—which has an elemental composition similar (but not identical) to the ceramic second-generation heavy metal Chobham armor of the Abrams tank—is an effective radiation shield, to both fission neutrons and gamma rays due to it being a graded-Z material. Uranium, being about twice as dense as lead, is thus nearly twice as effective at shielding gamma ray radiation per unit thickness.

Use against ballistic missiles
As an anti-ballistic missile weapon, the first fielded ER warhead, the W66, was developed for the Sprint missile system as part of the Safeguard Program to protect United States cities and missile silos from incoming Soviet warheads.

A problem faced by Sprint and similar ABMs was that the blast effects of their warheads change greatly as they climb and the atmosphere thins out. At higher altitudes, starting around 60,000 feet and above, the blast effects begin to drop off rapidly as the air density becomes very low. This can be countered by using a larger warhead, but then it becomes too powerful when used at lower altitudes. An ideal system would use a mechanism that was less sensitive to changes in air density.

Neutron-based attacks offer one solution to this problem. The burst of neutrons released by an ER weapon can induce fission in the fissile materials of primary in the target warhead. The energy released by these reactions may be enough to melt the warhead, but even at lower fission rates, the "burning up" of some of the fuel in the primary can cause it to fail to explode properly, or "fizzle". Thus, a small ER warhead can be effective across a wide altitude band, using blast effects at lower altitudes and the increasingly long-ranged neutrons as the engagement rises.

The use of neutron-based attacks was discussed as early as the 1950s, with the US Atomic Energy Commission mentioning weapons with a "clean, enhanced neutron output" for use as "antimissile defensive warheads." Studying, improving and defending against such attacks was a major area of research during the 1950s and '60s. A particular example of this is the US Polaris A-3 missile, which delivered three warheads travelling on roughly the same trajectory, and thus with a short distance between them. A single ABM could conceivably destroy all three through neutron flux. Developing warheads that were less sensitive to these attacks was also a major area of research in the US and UK during the 1960s.

Some sources claim that the neutron flux attack was also the main design goal of the various nuclear-tipped anti-aircraft weapons like the AIM-26 Falcon and CIM-10 Bomarc. One F-102 pilot noted:

"GAR-11/AIM-26 was primarily a weapon-killer. The bomber(s, if any) was collateral damage. The weapon was proximity-fused to ensure detonation close enough so an intense flood of neutrons would result in an instantaneous nuclear reaction (NOT full-scale) in the enemy weapon's pit; rendering it incapable of functioning as designed ... [O]ur first 'neutron bombs' were the GAR-11 and MB-1 Genie."

It has also been suggested that neutron flux's effects on the warhead electronics are another attack vector for ER warheads in the ABM role. Ionization greater than 50 Gray in silicon chips delivered over seconds to minutes will degrade the function of semiconductors for long periods. However, while such attacks might be useful against guidance systems, which used relatively advanced electronics, in the ABM role, these components have long ago separated from the warheads by the time they come within range of the interceptors. The electronics in the warheads themselves tend to be very simple, and hardening them was one of the many issues studied in the 1960s.

Lithium-6 hydride (Li6H) is cited as being used as a countermeasure to reduce the vulnerability and "harden" nuclear warheads from the effects of externally generated neutrons. Radiation hardening of the warhead's electronic components as a countermeasure to high altitude neutron warheads somewhat reduces the range that a neutron warhead could successfully cause an unrecoverable glitch by the transient radiation effects on electronics (TREE) effects.

At very high altitudes, at the edge of the atmosphere and above it, another effect comes into play. At lower altitudes, the X-rays generated by the bomb are absorbed by the air and have mean free paths on the order of meters. But as the air thins out, the X-rays can travel further, eventually outpacing the area of effect of the neutrons. In exoatmospheric explosions, this can be on the order of 10 km in radius. In this sort of attack, it is the X-rays promptly delivering energy on the warhead surface that is the active mechanism; the rapid ablation (or "blowoff") of the surface creates shock waves that can break up the warhead.

Use as an area denial weapon
In November 2012, British Labour peer Lord Gilbert suggested that multiple enhanced radiation reduced blast (ERRB) warheads could be detonated in the mountain region of the Afghanistan-Pakistan border to prevent infiltration. He proposed to warn the inhabitants to evacuate, then irradiate the area, making it unusable and impassable. Used in this manner, the neutron bomb(s), regardless of burst height, would release neutron activated casing materials used in the bomb, and depending on burst height, create radioactive soil activation products.

In much the same fashion as the area denial effect resulting from fission product (the substances that make up most fallout) contamination in an area following a conventional surface-burst nuclear explosion, as considered in the Korean War by Douglas MacArthur, it would thus be a form of radiological warfare—with the difference that neutron bombs produce half, or less, of the quantity of fission products relative to the same-yield pure fission bomb. Radiological warfare with neutron bombs that rely on fission primaries would thus still produce fission fallout, albeit a comparatively cleaner and shorter-lasting version of it in the area than if air bursts were used, as little to no fission products would be deposited on the direct immediate area, instead becoming diluted global fallout. A militarily useful use of a neutron bomb with respect to area denial would be to encase it in a thick shell of material that could be neutron activated, and use a surface burst. In this manner, the neutron bomb would be turned into a salted bomb; for example, zinc-64, produced as a byproduct of depleted zinc oxide enrichment, would when neutron activated become zinc-65, which is a gamma emitter with a half-life of 244 days.

Hypothetical effects of a pure fusion bomb
With considerable overlap between the two devices, the prompt radiation effects of a pure fusion weapon would similarly be much higher than that of a pure-fission device: approximately twice the initial radiation output of current standard fission–fusion-based weapons. In common with all neutron bombs that must presently derive a small percentage of trigger energy from fission, in any given yield, a 100% pure fusion bomb would likewise generate a smaller atmospheric blast wave than a pure-fission bomb. The latter fission device has a higher kinetic energy-ratio per unit of reaction energy released, which is most notable in the comparison with the D-T fusion reaction. A larger percentage of the energy from a D-T fusion reaction is inherently put into uncharged neutron generation as opposed to charged particles, such as the alpha particle of the D-T reaction, the primary species, that is most responsible for the coulomb explosion/fireball.

List of US neutron weapons
Anti-ballistic missile warheads
 * W65 — Sprint enhanced radiation warhead developed by Livermore (cancelled)
 * W66 — Sprint enhanced radiation warhead developed by Los Alamos (1975–1976)

Ballistic missile warheads
 * W63 — Lance enhanced radiation warhead developed by Livermore (cancelled)
 * W64 — Lance enhanced radiation warhead developed by Los Alamos (cancelled)
 * W70 Mod 3 — Lance enhanced radiation warhead developed by Livermore (1981–1992).

Artillery
 * W79 Mod 0 — 8 inch enhanced radiation artillery shell developed by Livermore (1976–1992)
 * W82 Mod 0 — 155 mm enhanced radiation artillery shell developed by Livermore (cancelled)

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

title: Neutron bomb


text:
Fighting Fantasy

Fighting Fantasy is a series of single-player role-playing gamebooks created by Steve Jackson and Ian Livingstone. The first volume in the series was published in paperback by Puffin in 1982.

The series distinguished itself by mixing Choose Your Own Adventure-style storytelling with a dice-based role-playing element included within the books themselves. The caption on many of the covers claimed each title was an adventure "in which YOU are the hero!" The majority of the titles followed a fantasy theme, although science fiction, post-apocalyptic, superhero, and modern horror gamebooks were also published. The popularity of the series led to the creation of merchandise such as action figures, board games, role-playing game systems, magazines, novels, and video games.

Puffin ended the series in 1995, but the rights to the series were eventually purchased by Wizard Books in 2002. Wizard published new editions of the original books and also commissioned six new books over two series, ending in 2012. The rights were then acquired by Scholastic in 2017, which has since published four new titles and reissued thirteen of the original books with new artwork.

Overview
The main text of each gamebook does not progress in a linear fashion, but rather is divided into a series of numbered sections (usually 400, though a few are shorter or longer). Beginning at the first section, the reader typically must pick one of a series of options provided by the text, each option being detailed at a separate non-sequential numbered section (e.g. the reader may be presented with a choice to turn from section 1 directly to either section 83 or section 180) which in turn provides an outcome for the option chosen. The book continues in this fashion until their character is killed in combat, is stopped by the story, or completes the story. "Fighting Fantasy gamebooks empower the reader, who felt the anxiety or joy of being fantasy heroes themselves – they lived or died by their decisions. And if at first you don’t succeed, try and try again," said Ian Livingstone of the format.

The typical Fighting Fantasy gamebook tasks players with completing a quest. A successful play usually ends with the player reaching the final numbered section of the book. In some cases this can only be achieved by obtaining various story items (e.g. gems in Deathtrap Dungeon); many of the titles only feature one path to the solution.

All Fighting Fantasy gamebooks are illustrated, including full-page pieces and smaller, repeated images scattered throughout the book as breaks or space fillers between sections. Regular contributors (excluding Scholastic editions) included Les Edwards, Terry Oakes, Russ Nicholson, Leo Hartas, Ian Miller, John Blanche, Martin McKenna, and Iain McCaig.

System
Each Fighting Fantasy gamebook requires the reader to create their character, randomly assigning scores to three statistics (skill, stamina, and luck). These, in conjunction with rolling six-sided dice, are used to resolve skill challenges and the combat sections. Some titles use additional statistics or conflict resolution mechanics; most also require the reader to keep an inventory of items.

Setting
Most early Fighting Fantasy titles were set in locations later revealed to be on the same continent called Allansia. Later a whole world named Titan was developed, with subsequent gamebooks set on three main continents—Allansia, Khul and the Old World. Other titles are set in unrelated fantasy, horror, modern day, and sci-fi environments.

Publication history
In 1980, Steve Jackson (not to be confused with the US-based game designer of the same name) and Ian Livingstone attended a Games Day, and after meeting with a Penguin Books editor Geraldine Cook decided to create a series of single-player gamebooks. Their first submission, The Magic Quest, was a short adventure intended to demonstrate the style of game. The Magic Quest was eventually accepted by Penguin, although the authors devoted a further six months to expanding and improving upon their original concept.

Puffin Books (1982–1995)
The result was The Warlock of Firetop Mountain and, after several rewrites, the book was accepted and published in 1982 under Penguin's children's imprint, Puffin Books. Following the success of this title, Jackson and Livingstone began writing individually to create additional Fighting Fantasy gamebooks.

This series was published under Puffin's newly-created Adventure Gamebooks banner, which eventually would hold not only the Fighting Fantasy series, but The Cretan Chronicles trilogy, the Starlight Adventures series, and the individual role-playing game Maelstrom as well.

In 1983, The Citadel of Chaos and The Forest of Doom were published, by Jackson and Livingstone respectively. Four more titles quickly followed: Starship Traveller (the first title with a science fiction setting), City of Thieves, Deathtrap Dungeon, and Island of the Lizard King; Jackson writing one and Livingstone writing three. In 1984, a decision was made to hire additional writers to expand the series more quickly: Steve Jackson (the U.S.-based founder and owner of Steve Jackson Games) was the first, followed by others such as Andrew Chapman, Carl Sargent (aka Keith Martin), Marc Gascoigne, and Peter Darvill-Evans. Jackson and Livingstone, however, continued to be involved and approved all cover and internal illustrations within the UK.

Jackson wrote a self-contained four-part series titled Steve Jackson's Sorcery! (1983-1985), which combined the use of combat and sorcery, and introduced the continent later known as the Old World. These featured dice images at the bottom of each page, making it possible for the player to randomly flip through the pages for the equivalent of a dice roll (the Fighting Fantasy titles published by Wizard Books used the same device).

Andrew Chapman and Martin Allen also wrote a two-book, two-player adventure titled Clash of the Princes (1986). There were also several supplemental books produced that provided more information about the Fighting Fantasy universe, including a comprehensive bestiary of monsters and a sample adventure.

Although the Fighting Fantasy titles had successful sales the increasing dominance of video games in the 1990s caused a gradual decline. The series was scheduled to conclude with Return to Firetop Mountain (book 50, Livingstone, 1992), but due to strong sales of that volume, ten more books were scheduled. Nine were published, the series ending with Curse of the Mummy (1995). Bloodbones, the tenth scheduled title (meant to have been book 60 in the series) was cancelled, but was eventually published by Wizard Books as part of their later reprinting efforts.

Series 1 (2002–2007)
In 2002, Wizard Books acquired the rights to the Fighting Fantasy series and reprinted many of the original titles in a revised order (initially only the gamebooks actually written by Jackson and/or Livingstone were published), starting with The Warlock of Firetop Mountain. They also incorporated the Sorcery! miniseries, as books 9, 11, 13, and 15. A new title, Eye of the Dragon (by Ian Livingstone) was released in 2005, followed by Bloodbones in 2006 and Howl of the Werewolf in 2007. This series used a new logo, the rationale being that the old covers did not suit the modern market.

2007 also marked the twenty-fifth anniversary of Fighting Fantasy, and to commemorate the event Wizard Books published a special hardcover edition of The Warlock of Firetop Mountain that used the original 1982 cover image and contained extra material such as the dungeon solution and a commentary on Fighting Fantasy by Livingstone. This series concluded that same year, ending with 29 books.

Series 2 (2009–2012)
Wizard Books then began again with a new series of reprints in 2009, again featuring a different cover art style, and again starting with The Warlock of Firetop Mountain. These books were physically larger than prior releases, being produced in B-format (like the original Advanced Fighting Fantasy volumes). Three other original titles were added during this run, including Blood of the Zombies by Ian Livingstone to celebrate the thirtieth anniversary in 2012. This series was 17 books long, although Blood of the Zombies, the last volume released, is unnumbered and packaged differently than the rest.

Scholastic Books (2017–)
A new Fighting Fantasy book by Livingstone, The Port of Peril, was published in August 2017 by Scholastic in celebration of the 35th anniversary of the series. Scholastic also released five of the original books. Instead of reusing the original artwork or its style, Scholastic commissioned new artwork. In April 2018, a further six titles were published, including a new adventure by author Charlie Higson, entitled The Gates of Death. Three more titles were published in September 2019, including Livingstone's new adventure Assassins of Allansia. In October 2020, two new titles were published, including a new adventure entitled Crystal of Storms, the first in the series by a female author, Rhianna Pratchett. In September 2022, two more new titles were published, one by Steve Jackson (Secrets of Salamonis) and one by Ian Livingstone (Shadow of the Giants), in celebration of the series' 40th anniversary.

Printed
Warlock magazine (first published by Puffin Books and later Games Workshop) provided additional information on the Fighting Fantasy universe, and each issue featured a short gamebook adventure, new rules, monsters, reviews and comic strips. It was published from 1983 to 1986 and ran for 13 issues in the UK. It was also published in other countries, and continued in Japan until 1997.

In 1984, Jackson published a roleplaying game, Fighting Fantasy – The Introductory Role-playing Game. A second game was published in 1989: Advanced Fighting Fantasy (AFF). AFF was re-released as a new and further expanded edition by Arion Games in 2011.

In 1985, Jackson wrote a picture gamebook with the title Tasks of Tantalon, in which the player was required to solve a series of puzzles which were presented as large, full-colour pictures containing hidden clues to be located and assembled.

The Warlock of Firetop Mountain (1986) and Legend of Zagor (1993) were released as board games by Games Workshop and Parker Brothers respectively.

Between 1989 and 1994, seven novels were published based on Fighting Fantasy, written by Steve Jackson, Marc Gascoigne, Ian Livingstone, and Carl Sargent.

In 1992, the Fighting Fantasy 10th Anniversary Yearbook (a diary with articles, trivia and a gamebook) was published.

In 2003, Jamie Wallis (not to be confused with James Wallis) adapted eight Fighting Fantasy and Sorcery! gamebooks to the D20 System. These adventures were published by Myriador (now defunct, though PDFs are still available for purchase from Greywood Publishing via third-party online retailers).

A comic series based on Freeway Fighter was published by Titan Comics in May 2017.

Audio
In September 2017, a series of audio dramas based on classic Fighting Fantasy titles was launched by FoxYason Productions at Fighting Fantasy Fest 2, starting with The Warlock of Firetop Mountain: The Hero's Quest. A boxset of four more titles was released in 2018.

Video games
Several Fighting Fantasy titles have been released as video games, including seven Fighting Fantasy titles (The Warlock of Firetop Mountain, The Citadel of Chaos, The Forest of Doom, Temple of Terror, Seas of Blood, Appointment with F.E.A.R. and Rebel Planet) for the Commodore 64, Amstrad CPC, BBC, and Sinclair ZX Spectrum (1984) and Deathtrap Dungeon for the PC and PlayStation by Eidos Interactive (1998). On 18 August 2011 an adaption of Talisman of Death was released by UK developer Laughing Jackal for the PlayStation Minis platform (playable on the PlayStation Portable and PlayStation 3).

Cambridge-based studio Inkle released another interactive version of The Shamutanti Hills for iOS in May 2013, and has since gone on to release all four parts of Sorcery! on iOS, Android, Windows and Mac.

The video game The Warlock of Firetop Mountain: Goblin Scourge Edition was released by Tin Man Games for the Nintendo Switch on 13 September 2018.

Tin Man Games has also released the Fighting Fantasy Classics video game for Windows. Bloodbones is available for free and other titles are available as paid DLC.

Nomad Games released Deathtrap Dungeon Trilogy for the Nintendo Switch in 2019.

Mobile
On 5 December 2006, it was announced that Jackson and Livingstone were planning to release a new series of handheld games based on Fighting Fantasy for Nintendo DS and Sony's PSP. The first of these, Fighting Fantasy: The Warlock of Firetop Mountain, was released for the DS in the United States on 25 November 2009, and for the Apple iPhone and iPod in early January 2010.

On 10 February 2011 an Amazon Kindle edition of The Warlock of Firetop Mountain was launched by UK developer Worldweaver Ltd, for the US market. Warlock and four other gamebooks were released on iOS by Big Blue Bubble, but were removed from the app store in 2012 when they lost the licence.

Australian game developers Tin Man Games have since published several iOS and Android versions of Fighting Fantasy books, including Blood of the Zombies, House of Hell, Forest of Doom, Island of the Lizard King and Starship Traveller, and an iOS version of the first part of the Sorcery! series was released by Bright Al Ltd in 2010.

Inkle's Sorcery! series is available on iOS, Android, Windows and Mac.

Reception
In March 1983, the top three entries of the Sunday Times bestseller list were occupied by Fighting Fantasy books. The series sold 20 million copies in the 80s and 90s.

Fighting Fantasy was ranked 47th in the 1996 reader poll of Arcane magazine to determine the 50 most popular roleplaying games of all time. The UK magazine's editor Paul Pettengale commented: "To say that it is basic would be a huge understatement – Fighting Fantasy has just a couple of stats from which a character is created, and combat is a simple case of rolling six-sided dice, pitching one creature's stats against another. It's fun, quick and easy, which explains its popularity."

Moral panic
The books were published with illustrations from Games Workshop which, though something Puffin was resistant to accept, Ian Livingstone credits as part of the series' success. However, partially as a result of the covers, the game, along with Dungeons & Dragons, became subject to a moral panic. The Evangelical Alliance issued a warning that the books would lead to players interacting with the devil, while parents reported that after reading their children developed supernatural powers, including one mother who reported that her child started to fly. When asked about the controversy, Jackson replied that they were very grateful for it, as it helped their sales figures. Game historian Stu Horvath commented "The moral panic didn't dent sales. The Warlock of Firetop Mountain and the Fighting Fantasy series proved to be a massive on-ramp for bringing new players into the RPG hobby, particularly in the British commonwealth ... Firetop Mountain alone was reprinted five times in 1982, ten times in 1983, and seven more in 1984, eventually selling well over two million copies and inspiring a popular board game to boot."

Reviews

 * Isaac Asimov's Science Fiction Magazine

title: Fighting Fantasy


text:
Mount Aetna

Mount Aetna may refer to:

 * Mount Etna, a stratovolcano in Sicily.
 * Mount Aetna (Colorado), a mountain in Colorado
 * Mount Aetna, Maryland, a census-designated place in the United States
 * Mount Aetna, Pennsylvania, an unincorporated community in the United States

title: Mount Aetna


text:
National Academies of Sciences, Engineering, and Medicine

The National Academies of Sciences, Engineering, and Medicine (NASEM), also known as the National Academies, is a congressionally chartered organization that serves as the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrella term or parent organization for its three sub-divisions that operate as quasi-independent honorific learned society member organizations known as the National Academy of Sciences (NAS), the National Academy of Engineering (NAE), and the National Academy of Medicine (NAM); and (2) as the brand for studies and reports issued by the unified operating arm of the three academies originally known as the National Research Council (NRC). The National Academies also serve as public policy advisors, research institutes, think tanks, and public administration consultants on issues of public importance or on request by the government.

The National Research Council, National Academy of Engineering, and National Academy of Medicine began as activities of the National Academy of Sciences until they were reorganized in 2015 into units of the current National Academies while maintaining the charter status and corporate successorship of the original National Academy of Sciences.

Now jointly governed by all three academies, the NRC produces some 200 publications annually which are published by the National Academies Press. The reports produced by the National Academies have been characterized as reflective of scientific consensus.

History
The US National Academy of Sciences was created by an Act of Incorporation dated March 3, 1863, which was signed by then President of the United States, Abraham Lincoln. The Act stated that "... the Academy shall, whenever called upon by any department of the Government, investigate, examine, experiment, and report upon any subject of science or art. ... " With the American civil war raging, the new Academy was presented with few problems to solve, but it did address matters of "... coinage, weights and measures, iron ship hulls, and the purity of whiskey ..." All subsequently affiliated organizations have been created under this same overall congressional charter, including the two younger academies, National Academy of Engineering (NAE) (created in 1964) and NAM (created as the Institute of Medicine in 1970 and rechartered as NAM in 2015).

Under this same charter, the National Research Council was created in 1916. On June 19 of that year, then US President Woodrow Wilson requested that the National Academy of Sciences organize a "National Research Council". The purpose of the Council (at first called the National Research Foundation) was in part to foster and encourage "the increased use of scientific research in the development of American industries ... the employment of scientific methods in strengthening the national defense ... and such other applications of science as will promote the national security and welfare."

At the time, the Academy's effort to support national defense readiness, the Committee on Nitric Acid Supply, was approved by Secretary of War Newton D. Baker. Nitric acid was the substance basic in the making of propellants such as cordite, high explosives, dyes, fertilizers, and other products but availability was limited due to World War I. The NRC, through its committee, recommended importing Chilean saltpeter and the construction of four new ordnance plants. These recommendations were accepted by the War Department in June 1917, although the plants were not completed prior to the end of the war. In 1918, Wilson formalized the NRC's existence under Executive Order 2859. Wilson's order declared the function of the NRC to be in general:
 * "(T)o stimulate research in the mathematical. physical, and biological sciences. and in the application of these sciences to engineering, agriculture. medicine. and other useful arts. with the object of increasing knowledge, of strengthening the national defense, and of contributing in other ways to the public welfare."

During World War I, the United States was at war, the NRC operated as the Department of Science and Research of the Council of National Defense as well as the Science and Research Division of the United States Army Signal Corps. When war was first declared, the Council had organized committees on anti-submarine and gas warfare.

On June 1, 1917, the council convened a meeting of scientific representatives of the United Kingdom and France with interested parties from the U.S. on the subject of submarine detection. Another meeting with the British and French was held in Paris in October 1918, at which more details of their work were disclosed. As a result of these meetings, the NRC recommended that scientists be brought together to work on the problems associated with submarine detection. Due to the success of council-directed research in producing a sound-based method of detecting submarines, as well as other military innovations, the NRC was retained at the end of the war, though it was gradually decoupled from the military.

NRC's Articles of Organization have been changed only three times: in 1956, January 1993, and July 2015.

The Academies
The National Academy of Sciences, National Academy of Engineering, and National Academy of Medicine are honorary membership organizations, each of which has its own governing Council, and each of which elects its own new members. The membership of the three academies totals more than 6,300 scientists, engineers, and health professionals. New members for each organization are elected annually by existing members, based on their distinguished and continuing achievements in original research. By the terms of the original 1863 Congressional charter, the three academies serve pro bono as "advisers to the nation on science, engineering, and medicine."

Program units
The program units, formerly known as the National Research Council, are collectively the operating arm of the three academies for the purpose of providing objective policy advice. Although separately chartered (see above), it falls legally under the overall charter of the National Academy of Sciences, whose ultimate fiduciary body is the NAS Council. In actual practice, the NAS Council delegates governing authority to a Governing Board of the National Research Council that is chaired jointly by the presidents of the three academies, with additional members chosen by them or specified in the charters of the academies.

Under this three-academy umbrella, the program units produce reports that shape policies, inform public opinion, and advance the pursuit of science, engineering, and medicine.

There are seven major divisions: Division of Behavioral and Social Sciences and Education, Division of Earth and Life Studies, Division of Engineering and Physical Sciences, Health and Medicine Division, Policy and Global Affairs Division, Transportation Research Board, and the Gulf Research Program.

Division of Behavioral and Social Sciences and Education (DBASSE)
====Units of the Division of Behavioral and Social Sciences and Education ====

 * Board on Children, Youth, and Families (BCYF)
 * Board on Behavioral, Cognitive, and Sensory Sciences (BBCSS)
 * Board on Human-Systems Integration (BOHSI)
 * Board on Environmental Change and Society (BECS)
 * Board on Science Education (BOSE)
 * Committee on Law and Justice (CLAJ)
 * Board on Testing and Assessment (BOTA)
 * Committee on Population (CPOP)
 * Committee on National Statistics (CNSTAT)

Division on Earth and Life Studies (DELS)
====Units of the Division on Earth and Life Studies ====

 * Board on Agriculture and Natural Resources (BANR)
 * Board on Atmospheric Sciences and Climate (BASC)
 * Board on Chemical Sciences and Technology (BCST)
 * Board on Earth Sciences and Resources (BESR)
 * Board on Environmental Studies and Toxicology (BEST)
 * Board on Life Sciences (BLS)
 * Institute for Laboratory Animal Research (ILAR)
 * Nuclear and Radiation Studies Board (NRSB)
 * Ocean Studies Board (OSB)
 * Polar Research Board (PRB)
 * Water Science and Technology Board (WSTB)

Division on Engineering and Physical Sciences (DEPS)
The Division on Engineering and Physical Sciences has activities organized around:
 * Government missions in defense, space, and aerospace
 * National infrastructure challenges such as energy and environmental systems, information and telecommunications, manufacturing and engineering design, civil engineering, and the built or constructed environment inclusive of its Board on Infrastructure and Constructed Environment or BICE
 * Science and engineering disciplines such as physics, astronomy, computer science and engineering, materials science and engineering, and the mathematical sciences and their applications.
 * Continuing assessments of federal government laboratories and research programs.

====Units of the Division on Engineering and Physical Sciences ====

 * Aeronautics and Space Engineering Board (ASEB)
 * Air Force Studies Board (AFSB)
 * Board on Army Research and Development (BOARD)
 * Board on Energy and Environmental Systems (BEES)
 * Board on Infrastructure and the Constructed Environment (BICE)
 * Board on Mathematical Sciences and Analytics (BMSA)
 * Board on Physics and Astronomy (BPA)
 * Computer Science and Telecommunications Board (CSTB)
 * Intelligence Community Studies Board (ICSB)
 * Laboratory Assessments Board (LAB)
 * National Materials and Manufacturing Board (NMMB)
 * Naval Studies Board (NSB)
 * Space Studies Board (SSB)

Health and Medicine Division (HMD)
====Units of the Health and Medicine Division ====

 * Board on Children, Youth, and Families (BCYF)
 * Board on Global Health (BGH)
 * Board on Health Care Services (HCS)
 * Board on Health Sciences Policy (HSP)
 * Board on Population Health and Public Health Practice (BPH)
 * Food and Nutrition Board (FNB)

Policy and Global Affairs Division (PGA)
====Units of the Policy and Global Affairs Division ====

 * Board on Higher Education and Workforce (BHEW)
 * Board on International Scientific Organizations (BISO)
 * Board on Research Data and Information (BRDI)
 * Board on Science, Technology, and Economic Policy (STEP)
 * Committee on Human Rights (CHR)
 * Committee on International Security and Arms Control (CISAC)
 * Committee on Science, Engineering, Medicine, and Public Policy (COSEMPUP)
 * Committee on Science, Technology, and Law (CSTL)
 * Committee on Women in Science, Engineering, and Medicine (CWSEM)
 * Fellowships Office
 * Government-University-Industry Research Roundtable (GUIRR)
 * Resilient America Program
 * Science and Technology for Sustainability (STS)

Units of the Transportation Research Board

 * Consensus and Advisory Studies Division
 * Cooperative Research Programs Division
 * Airport Cooperative Research Program (ACRP)
 * National Cooperative Highway Research Program (NCHRP)
 * Behavioral Traffic Safety Cooperative Research Program (BTSCRP)
 * National Cooperative Research and Evaluation Program (NCREP)
 * Transit Cooperative Research Program (TCRP)
 * National Cooperative Freight Research Program (NCFRP)
 * National Cooperative Rail Research Program (NCRRP)
 * Hazardous Materials Cooperative Research Program (HMCRP)

Study process
The National Academies attempt to obtain authoritative, objective, and scientifically balanced answers to difficult questions of national importance. Top scientists, engineers, health professionals, and other experts (not limited to those in academies membership) are enlisted to address the scientific and technical aspects of some of society's problems. These experts are volunteers who serve on study committees that are convened to answer specific sets of questions. All committee members serve without pay.

NASEM does not perform original research; rather it provides independent advice. Federal agencies are the primary financial sponsors of the Academies' work; additional studies are funded by state agencies, foundations, other private sponsors, and the National Academies endowment. The external sponsors have no control over the conduct or results of a study, once the statement of task and budget are finalized. Study committees gather information from many sources in public meetings but deliberate in private in order to avoid political, special interest, and sponsor influence.

All reports go through an extensive external review facilitated by the internal Report Review Committee (also consisting of members from the NAS, NAE, and NAM).

Through this study process, the National Academies produce around 200 reports each year. Recent reports addressed the obesity epidemic, the use of forensics in the courtroom, invasive plants, pollinator collapse, underage drinking, the Hubble Space Telescope, vaccine safety, the hydrogen economy, transportation safety, climate change, and homeland security. Many reports influence policy decisions; some are instrumental in enabling new research programs; others provide independent program reviews. The National Academies Press is the publisher for the National Academies of Sciences, Engineering, and Medicine, and makes its publications available for free online reading. The full book PDFs have been available for free download since 2011.

The National Academies also provide credentialed witnesses who speak before government bodies on important issues. For example a committee chair may speak on rising mortality rates in working adults in the US to a Senate Subcommittee on Primary Health and Retirement Security, Committee on Health, Education, Labor and Pensions.

Climate change
In 2001, the NRC published the report Climate Change Science: An Analysis of Some Key Questions, which emphasized that national policy decisions made both in the near term and in the future will influence the extent of any damage suffered by vulnerable human populations and ecosystems later in this century. The report endorsed findings of the Intergovernmental Panel on Climate Change (IPCC) as representing the views of the scientific community:

"The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes is also a reflection of natural variability. Human-induced warming and associated sea level rise are expected to continue through the 21st century ... The IPCC's conclusion that most of the observed warming of the last 50 years is likely to have been due to the increase in greenhouse gas concentrations accurately reflects the current[2001] thinking of the scientific community on this issue."

In 2013, the NRC published the report Abrupt Impacts of Climate Change: Anticipating Surprises, which provided an updated look at the issue of abrupt climate change and its potential impacts. This study differed from previous treatments of abrupt changes by focusing on abrupt climate changes and also abrupt climate impacts that have the potential to severely affect the physical climate system, natural systems, or human systems, often affecting multiple interconnected areas of concern.

Sexual assault
In 2013, the NRC published the report Estimating the Incidence of Rape and Sexual Assault, which pointed out that approximately 80 percent of sexual assaults go unreported to law enforcement. The report recommends that the National Crime Victimization Survey adopt new approaches to interviews of rape victims, including changing the wording of questions.

In an article about the report, Amber Stevenson, clinical supervisor and therapist at the Nashville Sexual Assault Center, said that victim-blaming was the main issue preventing victims from coming forward: "As long as we as a community continue to make victim-blaming statements, such as, 'She put herself in this situation,'...'She didn't fight back, she must have wanted it,' we will continue to see rapes go unreported ... We have to stop blaming the victim. The conversation needs to shift to the person who chose to rape."

Integrity in research
The 1992 report, Responsible Science: Ensuring the Integrity of the Research Process was updated in 2017 by the report, Fostering Integrity in Research:

"... as experience has accumulated with various forms of research misconduct, detrimental research practices, and other forms of misconduct, as subsequent empirical research has revealed more about the nature of scientific misconduct, and because technological and social changes have altered the environment in which science is conducted, it is clear that the framework established more than two decades ago needs to be updated."

One of the report's main concerns is that a growing percentage of recently published research turns out to be not reproducible due in part to inadequate support of standards of transparency in many fields as well as to various other detrimental research practices.

Other programs
The Christine Mirzayan Science and Technology Policy Fellowship is an annual program for recent graduate students to spend three months working in the National Academies. The Academies also administered the Marian Koshland Science Museum in downtown Washington until its closing in 2017; the Museum has since been replaced by LabX, a program of online resources and nationwide public events that aim to increase awareness of scientific and evidence-based solutions to community problems.

Revenue
The National Academies do not receive direct appropriations from the federal government; instead their revenue comes from grants and contracts of federal agencies and private sources. According to the New York Times in 2023, "about 70 percent of the National Academies budget comes from federal funds, it also raised private donations from individuals, nonprofits and companies, including Chevron, Google, Merck, and Medtronic." At the time it was advising the government on opioid policy, it received $19 million from Purdue Pharma's Sackler family between 2000 and 2021.


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Encephalitis

Encephalitis is inflammation of the brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.

Causes of encephalitis include viruses such as herpes simplex virus and rabies virus as well as bacteria, fungi, or parasites. Other causes include autoimmune diseases and certain medications. In many cases the cause remains unknown. Risk factors include a weak immune system. Diagnosis is typically based on symptoms and supported by blood tests, medical imaging, and analysis of cerebrospinal fluid.

Certain types are preventable with vaccines. Treatment may include antiviral medications (such as acyclovir), anticonvulsants, and corticosteroids. Treatment generally takes place in hospital. Some people require artificial respiration. Once the immediate problem is under control, rehabilitation may be required. In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide.

Signs and symptoms
Adults with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present with irritability, poor appetite and fever. Neurological examinations usually reveal a drowsy or confused person. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningoencephalitis.

Cause
In 30%-40% of encephalitis cases, the etiology remains unknown.

Viral
Viral infections are the usual cause of infectious encephalitis. Viral encephalitis can occur either as a direct effect of an acute infection, or as one of the sequelae of a latent infection. The majority of viral cases of encephalitis have an unknown cause; however, the most common identifiable cause of viral encephalitis is from herpes simplex infection. Other causes of acute viral encephalitis are rabies virus, poliovirus, and measles virus.

Additional possible viral causes are arboviral flavivirus (St. Louis encephalitis, West Nile virus), bunyavirus (La Crosse strain), arenavirus (lymphocytic choriomeningitis virus), reovirus (Colorado tick virus), and henipavirus infections. The Powassan virus is a rare cause of encephalitis.

Bacterial and other
It can be caused by a bacterial infection, such as bacterial meningitis, or may be a complication of a current infectious disease such as syphilis (secondary encephalitis).

Certain parasitic or protozoal infestations, such as toxoplasmosis, malaria, or primary amoebic meningoencephalitis, can also cause encephalitis in people with compromised immune systems. Lyme disease or Bartonella henselae may also cause encephalitis.

Other bacterial pathogens, like Mycoplasma and those causing rickettsial disease, cause inflammation of the meninges and consequently encephalitis. A non-infectious cause includes acute disseminated encephalitis which is demyelinated.

Limbic encephalitis
Limbic encephalitis refers to inflammatory disease confined to the limbic system of the brain. The clinical presentation often includes disorientation, disinhibition, memory loss, seizures, and behavioral anomalies. MRI imaging reveals T2 hyperintensity in the structures of the medial temporal lobes, and in some cases, other limbic structures. Some cases of limbic encephalitis are of autoimmune origin.

Autoimmune encephalitis
Autoimmune encephalitis signs can include catatonia, psychosis, abnormal movements, and autonomic dysregulation. Antibody-mediated anti-N-methyl-D-aspartate-receptor encephalitis and Rasmussen encephalitis are examples of autoimmune encephalitis. Anti-NMDA receptor encephalitis is the most common autoimmune form, and is accompanied by ovarian teratoma in 58 percent of affected women 18–45 years of age.

Encephalitis lethargica
Encephalitis lethargica is identified by high fever, headache, delayed physical response, and lethargy. Individuals can exhibit upper body weakness, muscular pains, and tremors, though the cause of encephalitis lethargica is not currently known. From 1917 to 1928, an epidemic of encephalitis lethargica occurred worldwide.

Diagnosis
People should only be diagnosed with encephalitis if they have a decreased or altered level of consciousness, lethargy, or personality change for at least twenty-four hours without any other explainable cause. Diagnosing encephalitis is done via a variety of tests:
 * Brain scan, done by MRI, can determine inflammation and differentiate from other possible causes.
 * EEG, in monitoring brain activity, encephalitis will produce abnormal signal.
 * Lumbar puncture (spinal tap), this helps determine via a test using the cerebral-spinal fluid, obtained from the lumbar region.
 * Blood test
 * Urine analysis
 * Polymerase chain reaction (PCR) testing of the cerebrospinal fluid, to detect the presence of viral DNA which is a sign of viral encephalitis.

Prevention
Vaccination is available against tick-borne and Japanese encephalitis  and should be considered for at-risk individuals. Post-infectious encephalomyelitis complicating smallpox vaccination is avoidable, for all intents and purposes, as smallpox is nearly eradicated. Contraindication to Pertussis immunization should be observed in patients with encephalitis.

Treatment
An ideal drug to treat brain infection should be small, moderately lipophilic at pH of 7.4, low level of plasma protein binding, volume of distribution of litre per kg, does not have strong affinity towards binding with P-glycoprotein, or other efflux pumps on the surface of blood–brain barrier. Some drugs such as isoniazid, pyrazinamide, linezolid, metronidazole, fluconazole, and some fluoroquinolones have good penetration to blood brain barrier. Treatment (which is based on supportive care) is as follows: • Antiviral medications (if virus is cause)

• Antibiotics, (if bacteria is cause)

• Steroids are used to reduce brain swelling

• Sedatives for restlessness

• Acetaminophen for fever

• Occupational and physical therapy (if brain is affected post-infection)

Pyrimethamine-based maintenance therapy is often used to treat toxoplasmic encephalitis (TE), which is caused by Toxoplasma gondii and can be life-threatening for people with weak immune systems. The use of highly active antiretroviral therapy (HAART), in conjunction with the established pyrimethamine-based maintenance therapy, decreases the chance of relapse in patients with HIV and TE from approximately 18% to 11%. This is a significant difference as relapse may impact the severity and prognosis of disease and result in an increase in healthcare expenditure.

The effectiveness of intravenous immunoglobulin for the management of childhood encephalitis is unclear. Systematic reviews have been unable to draw firm conclusions because of a lack of randomised double-blind studies with sufficient numbers of patients and sufficient follow-up. There is the possibility of a benefit of intravenous immunoglobulin for some forms of childhood encephalitis on some indicators such as length of hospital stay, time to stop spasms, time to regain consciousness, and time to resolution of neuropathic symptoms and fever. Intravenous immunoglobulin for Japanese encephalitis appeared to have no benefit when compared with placebo (pretend) treatment.

Prognosis
Identification of poor prognostic factors include cerebral edema, status epilepticus, and thrombocytopenia. In contrast, a normal encephalogram at the early stages of diagnosis is associated with high rates of survival.

Epidemiology
The number of new cases a year of acute encephalitis in Western countries is 7.4 cases per 100,000 people per year. In tropical countries, the incidence is 6.34 per 100,000 people per year. The number of cases of encephalitis has not changed much over time, with about 250,000 cases a year from 2005 to 2015 in the US. Approximately seven per 100,000 people were hospitalized for encephalitis in the US during this time. In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide. Herpes simplex encephalitis has an incidence of 2–4 per million of the population per year.

Terminology
Encephalitis with meningitis is known as meningoencephalitis, while encephalitis with involvement of the spinal cord is known as encephalomyelitis.

The word is from Ancient Greek, enképhalos 'brain', composed of , en, 'in' and , kephalé, 'head', and the medical suffix -itis 'inflammation'.

title: Encephalitis


text:
Nucleophile

In chemistry, a nucleophile is a chemical species that forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles. Because nucleophiles donate electrons, they are Lewis bases.

Nucleophilic describes the affinity of a nucleophile to bond with positively charged atomic nuclei. Nucleophilicity, sometimes referred to as nucleophile strength, refers to a substance's nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophilic reactions with solvents such as alcohols and water are named solvolysis. Nucleophiles may take part in nucleophilic substitution, whereby a nucleophile becomes attracted to a full or partial positive charge, and nucleophilic addition. Nucleophilicity is closely related to basicity. The difference between the two is, that basicity is a thermodynamic property (i.e. relates to an equilibrium state), but nucleophilicity is a kinetic property, which relates to rates of certain chemical reactions.

History and Etymology
The terms nucleophile and electrophile were introduced by Christopher Kelk Ingold in 1933, replacing the terms anionoid and cationoid proposed earlier by A. J. Lapworth in 1925. The word nucleophile is derived from nucleus and the Greek word φιλος, philos, meaning friend.

Properties
In general, in a group across the periodic table, the more basic the ion (the higher the pKa of the conjugate acid) the more reactive it is as a nucleophile. Within a series of nucleophiles with the same attacking element (e.g. oxygen), the order of nucleophilicity will follow basicity. Sulfur is in general a better nucleophile than oxygen.

Nucleophilicity
Many schemes attempting to quantify relative nucleophilic strength have been devised. The following empirical data have been obtained by measuring reaction rates for many reactions involving many nucleophiles and electrophiles. Nucleophiles displaying the so-called alpha effect are usually omitted in this type of treatment.

Swain–Scott equation
The first such attempt is found in the Swain–Scott equation derived in 1953:
 * $$\log_{10}\left(\frac{k}{k_0}\right) = sn$$

This free-energy relationship relates the pseudo first order reaction rate constant (in water at 25 °C), k, of a reaction, normalized to the reaction rate, k0, of a standard reaction with water as the nucleophile, to a nucleophilic constant n for a given nucleophile and a substrate constant s that depends on the sensitivity of a substrate to nucleophilic attack (defined as 1 for methyl bromide).

This treatment results in the following values for typical nucleophilic anions: acetate 2.7, chloride 3.0, azide 4.0, hydroxide 4.2, aniline 4.5, iodide 5.0, and thiosulfate 6.4. Typical substrate constants are 0.66 for ethyl tosylate, 0.77 for β-propiolactone, 1.00 for 2,3-epoxypropanol, 0.87 for benzyl chloride, and 1.43 for benzoyl chloride.

The equation predicts that, in a nucleophilic displacement on benzyl chloride, the azide anion reacts 3000 times faster than water.

Ritchie equation
The Ritchie equation, derived in 1972, is another free-energy relationship:
 * $$\log_{10}\left(\frac{k}{k_0}\right) = N^+$$

where N+ is the nucleophile dependent parameter and k0 the reaction rate constant for water. In this equation, a substrate-dependent parameter like s in the Swain–Scott equation is absent. The equation states that two nucleophiles react with the same relative reactivity regardless of the nature of the electrophile, which is in violation of the reactivity–selectivity principle. For this reason, this equation is also called the constant selectivity relationship.

In the original publication the data were obtained by reactions of selected nucleophiles with selected electrophilic carbocations such as tropylium or diazonium cations:
 * RichieEquationDiazonium.png

or (not displayed) ions based on malachite green. Many other reaction types have since been described.

Typical Ritchie N+ values (in methanol) are: 0.5 for methanol, 5.9 for the cyanide anion, 7.5 for the methoxide anion, 8.5 for the azide anion, and 10.7 for the thiophenol anion. The values for the relative cation reactivities are −0.4 for the malachite green cation, +2.6 for the benzenediazonium cation, and +4.5 for the tropylium cation.

Mayr–Patz equation
In the Mayr–Patz equation (1994):
 * $$\log(k) = s(N + E)$$

The second order reaction rate constant k at 20 °C for a reaction is related to a nucleophilicity parameter N, an electrophilicity parameter E, and a nucleophile-dependent slope parameter s. The constant s is defined as 1 with 2-methyl-1-pentene as the nucleophile.

Many of the constants have been derived from reaction of so-called benzhydrylium ions as the electrophiles:
 * Benzhydryliumion.png

and a diverse collection of π-nucleophiles:
 * MayrNucleophiles.png.

Typical E values are +6.2 for R = chlorine, +5.90 for R = hydrogen, 0 for R = methoxy and −7.02 for R = dimethylamine.

Typical N values with s in parentheses are −4.47 (1.32) for electrophilic aromatic substitution to toluene (1), −0.41 (1.12) for electrophilic addition to 1-phenyl-2-propene (2), and 0.96 (1) for addition to 2-methyl-1-pentene (3), −0.13 (1.21) for reaction with triphenylallylsilane (4), 3.61 (1.11) for reaction with 2-methylfuran (5), +7.48 (0.89) for reaction with isobutenyltributylstannane (6) and +13.36 (0.81) for reaction with the enamine 7.

The range of organic reactions also include SN2 reactions:
 * Mayr2006.png

With E = −9.15 for the S-methyldibenzothiophenium ion, typical nucleophile values N (s) are 15.63 (0.64) for piperidine, 10.49 (0.68) for methoxide, and 5.20 (0.89) for water. In short, nucleophilicities towards sp2 or sp3 centers follow the same pattern.

Unified equation
In an effort to unify the above described equations the Mayr equation is rewritten as:
 * $$\log(k) = s_Es_N(N + E)$$

with sE the electrophile-dependent slope parameter and sN the nucleophile-dependent slope parameter. This equation can be rewritten in several ways:
 * with sE = 1 for carbocations this equation is equal to the original Mayr–Patz equation of 1994,
 * with sN = 0.6 for most n nucleophiles the equation becomes
 * $$\log(k) = 0.6s_EN + 0.6s_EE$$
 * or the original Scott–Swain equation written as:
 * $$\log(k) = \log(k_0) + s_EN$$

 * with sE = 1 for carbocations and sN = 0.6 the equation becomes:
 * $$\log(k) = 0.6N + 0.6E$$
 * or the original Ritchie equation written as:
 * $$\log(k) - \log(k_0) = N^+$$

Types
Examples of nucleophiles are anions such as Cl−, or a compound with a lone pair of electrons such as NH3 (ammonia) and PR3.

In the example below, the oxygen of the hydroxide ion donates an electron pair to form a new chemical bond with the carbon at the end of the bromopropane molecule. The bond between the carbon and the bromine then undergoes heterolytic fission, with the bromine atom taking the donated electron and becoming the bromide ion (Br−), because a SN2 reaction occurs by backside attack. This means that the hydroxide ion attacks the carbon atom from the other side, exactly opposite the bromine ion. Because of this backside attack, SN2 reactions result in a inversion of the configuration of the electrophile. If the electrophile is chiral, it typically maintains its chirality, though the SN2 product's absolute configuration is flipped as compared to that of the original electrophile.
 * hydrox subst.png

Ambident Nucleophile
An ambident nucleophile is one that can attack from two or more places, resulting in two or more products. For example, the thiocyanate ion (SCN−) may attack from either the sulfur or the nitrogen. For this reason, the SN2 reaction of an alkyl halide with SCN− often leads to a mixture of an alkyl thiocyanate (R-SCN) and an alkyl isothiocyanate (R-NCS). Similar considerations apply in the Kolbe nitrile synthesis.

Halogens
While the halogens are not nucleophilic in their diatomic form (e.g. I2 is not a nucleophile), their anions are good nucleophiles. In polar, protic solvents, F− is the weakest nucleophile, and I− the strongest; this order is reversed in polar, aprotic solvents.

Carbon
Carbon nucleophiles are often organometallic reagents such as those found in the Grignard reaction, Blaise reaction, Reformatsky reaction, and Barbier reaction or reactions involving organolithium reagents and acetylides. These reagents are often used to perform nucleophilic additions.

Enols are also carbon nucleophiles. The formation of an enol is catalyzed by acid or base. Enols are ambident nucleophiles, but, in general, nucleophilic at the alpha carbon atom. Enols are commonly used in condensation reactions, including the Claisen condensation and the aldol condensation reactions.

Oxygen
Examples of oxygen nucleophiles are water (H2O), hydroxide anion, alcohols, alkoxide anions, hydrogen peroxide, and carboxylate anions. Nucleophilic attack does not take place during intermolecular hydrogen bonding.

Sulfur
Of sulfur nucleophiles, hydrogen sulfide and its salts, thiols (RSH), thiolate anions (RS−), anions of thiolcarboxylic acids (RC(O)-S−), and anions of dithiocarbonates (RO-C(S)-S−) and dithiocarbamates (R2N-C(S)-S−) are used most often.

In general, sulfur is very nucleophilic because of its large size, which makes it readily polarizable, and its lone pairs of electrons are readily accessible.

Nitrogen
Nitrogen nucleophiles include ammonia, azide, amines, nitrites, hydroxylamine, hydrazine, carbazide, phenylhydrazine, semicarbazide, and amide.

Metal centers
Although metal centers (e.g., Li+, Zn2+, Sc3+, etc.) are most commonly cationic and electrophilic (Lewis acidic) in nature, certain metal centers (particularly ones in a low oxidation state and/or carrying a negative charge) are among the strongest recorded nucleophiles and are sometimes referred to as "supernucleophiles." For instance, using methyl iodide as the reference electrophile, Ph3Sn– is about 10000 times more nucleophilic than I–, while the Co(I) form of vitamin B12 (vitamin B12s) is about 107 times more nucleophilic. Other supernucleophilic metal centers include low oxidation state carbonyl metalate anions (e.g., CpFe(CO)2–).

Examples
The following table shows the nucleophilicity of some molecules with methanol as the solvent:

title: Nucleophile


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Lumbar disc disease

Lumbar disc disease is the drying out of the spongy interior matrix of an intervertebral disc in the spine. Many physicians and patients use the term lumbar disc disease to encompass several different causes of back pain or sciatica. In this article, the term is used to describe a lumbar herniated disc. It is thought that lumbar disc disease causes about one-third of all back pain.

Symptoms
Pain, loss of muscle strength and loss of touch sensation may occur if this herniation causes the compression of the most proximal part of the nerve closely neighbouring the intervertebral disc material. Pain is in the distribution of the nerve compressed, usually down the back of the leg, side of the calf and inside of the foot (sciatica). Most commonly, the nerve root between the fourth and fifth lumbar vertebrae or between the fifth lumbar vertebra and first sacral segment are impinged.

In symptomatic cases the diagnosis should be confirmed by an MRI scan. However, in cases with slight symptoms, a faster and cheaper CT scan (although it is inferior to MRI scan) may be recommended. While a CT scan can show the bony structures in more detail, an MRI scan can better portray soft tissue.

Genetics
An inheritable gene variation may cause increased susceptibility. People with a variation in a gene that encodes the cartilage intermediate-layer protein (CILP) were 1.6 times more likely to have the disease than persons without the variation. CILP is a normal component of disc tissue. The gene variant was hypothesized to disrupt normal building and maintenance of cartilage. However, this association was not replicated in a follow-up study of Finnish and Chinese individuals.

Diagnosis
Diagnosis can be made on clinical basis with MRI findings

Treatment
Initial treatment in lumbar disc disease is one or two days of bedrest (although growing number of studies shows that it makes little difference) and pain relieving medications. In cases with ongoing pain despite conservative treatments, a surgical operation that will remove the compressing disc material, a microdiscectomy or discectomy may be recommended to treat a lumbar disc herniation.

title: Lumbar disc disease