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Constantine famously adopted a chi-rho standard (first two letters).
- Xbar for crossbar (switch)
- X-country
- LaX for lacrosse
- In some (mostly British, that I'm aware of) place abbreviations: King's Cross and Charing Cross railway stations in London are always abbreviated KX and CX respectively.
In Henry Festing Jones's Samuel Butler : Author of Erewhon (1835-1902) : A Memoir (London: MacMillan, 1919), Jones reported the following little epiphany (ch. 19, p. 363). He found a copy of Erewhon (2/e) in a second-hand book shop, inscribed by the author. (He got it for 4/6 -- the bookseller didn't recognize the hand.)
``The Book of Machines'' is in three chapters, and the second of these chapters contains a passage about looking down from a high place upon crowded thoroughfares and being reminded by the moving people of the blood corpuscles travelling through our veins. ``No mention shall be made of sewers ... nor of the yawning jaws of the railway stations, whereby the circulation is carried directly into the heart,--which receive the venous lines and disgorge the arterial, with an eternal pulse of people.'' In the copy I bought Butler has underlined the words ``yawning jaws'' and written in the margin: ``See Cannon Street and Charing Cross railway stations from the bridges or the Embankment.''I do not know when he made the notes, but I at once remembered this passage in the Introduction to Alps and Sanctuaries: ``When, again, I think of Waterloo Bridge, and the huge, wide-opened jaws of those two Behemoths, the Cannon Street and Charing Cross railway stations, I am not sure that the prospect here is not even finer than from Fleet Street. ... How like it all is to some great bodily mechanism of which the people are the blood.''
Both of the stations mentioned are terminals that trains reach immediately after crossing the Thames. Thus, someone close to the river -- on a bridge or the Embankment -- is looking at the outer end of the station, where the trains come and go.
If the station has an overall roof, the wide opening below it for the tracks might indeed resemble ``yawning jaws.'' All the more so if the roof has the classical form of a great arch. (Many major stations in Europe have such an arch over the platforms. In North America they are rare, although I think the Union station in Washington, DC, is an example.)
Charing Cross and Cannon Street stations were opened in 1864 and 1866 respectively, and indeed had arched roofs -- spanning 6 and 8 tracks, resp. Alps and Sanctuaries was published in 1881. Butler did not live to see the collapse of the roof at CX in 1905. It was replaced by a low roof; in 1990, this was in turn was replaced by a modern development over the station, intended to be reminiscent the original station design. The roof at Cannon Street was heavily damaged by WWII bombing and never replaced. Some years later there was a development like that at CX.
In every Scrabble set, exactly one of the 100 tiles is an X. The other high-value letters (one tile each) are J (also 8 pts.), and Q and Z (ten points each).
Earlier, it was understood more in terms of its etymology (`salt former') and included at least one nonelemental species: cyanogen. Nowadays, cyanogen [the dimer (CN)2] is more likely to be called a pseudohalogen, and cyanide (CN-) a pseudohalide ion. The terms pseudohalogen and pseudohalide are applied to other carbon nitrogen compounds -- cyanate ion (OCN-), isocyanate ion (NCO-), fulminate ion (ONC-), thiocyanate ion (OCN-), thiocyanogen ((SCN)2), and cyanamide ion (NCN2-).
Hydrogen cyanide, unlike hydrogen halides (I mean nonpseudohalides) is a very weak acid,. This is bad news, because it means that cyanide salts exposed to acid react to release hydrogen cyanide, a very fast-acting poison.
I haven't checked old definitions yet, but possibly at some point in the nineteenth century, a halide was just the conjugate base of any hydro acid. One source I've seen claims that the term halogen was coined by Berzelius. That's plausible, but I have some doubts to assuage before I simply assert it as fact.
In specific instances even today, I imagine that X is used to represent halogens and pseudohalogens, or some subset. The reactions and solubilities of thiocyanates resemble those of bromides and iodides, so one might use X to represent any of those three in certain discussions. (Of course, X also serves as a generic symbol for any atomic or molecular species, when no more specific symbol is available.)
Röntgen, who discovered them in 1895, gave X-rays their name. For a long time, however, they were also known as ``Röntgen rays.'' His amazing discovery led others to seek new kinds of radiation, including ``N-rays'' which turned out to be a figment of discoverer R. Blondlot's imagination. More here.
If for some reason diacritical marks aren't being used (increasingly, this is due to ignorance rather than unavailability of the appropriate characters) Röntgen is spelled Roentgen. (In German, ä, ö, and ü are essentially interchangeable with ae, oe, and ue, respectively, for general words. People have preferences about how their names are spelled, however, so as a rule one uses a single form for each person's name and does not make the substitution unless it is unavoidable. Thus, the name of the Dichter Goethe is not normally written Göthe by any literate person.)
X is also widely used as a generic symbol in formulas of various sorts. Examples include OXR (for the government organizations like ONR) and in chemical formulas where confusion with usage in the halogen sense is unlikely (or unavoidable). An example of the latter occurs in the title and paper of L. W. Schroeder, M. Mathew, and W. E. Brown, ``XO4n- Ion Hydration. The Crystal Structure of Mg3(PO4)2.22H2O,'' in The Journal of Physical Chemistry, vol. 82, no. 21 (October 19, 1978), pp. 2335-2340. There, X refers to nonmetals in the nitrogen-group nonmetals phosphorus (the focus of the work, and the X for which new experimental data were reported) and arsenic, and the chalcogenide sulfur.
In his diaries, William E. Gladstone (1809-1890) marked with an ex his meetings with women who represented a moral danger -- mostly prostitutes whom he met in an, umm, missionary spirit, courting evil while doing good. He was already a prominent MP when he used the mark as a comment on his meetings in the late 1860's with Mrs. Laura Thistlewayte (a kept woman in her youth, a lay religious preacher after her marriage -- when she knew Gladstone).
The first transistor was the point-contact transistor, involving two metal points contacting a semiconductor (germanium) surface. The first working transistor of this type (``type-A'') was made by Walter Brattain in December 1947. (By some definition, Walter was a Chinese physicist: he was born in Amoy on February 10, 1902, where his father had a job teaching science and math.)
Brattain recognized the importance of the transistor from the beginning. He said this in a 1964 interview:
It is of interest to those that ask whether we knew how important this was, that the evening of the first day, when John [Bardeen] had come in and suggested the geometry, I told my riding group that night, going home, that I felt that I had that day taken part in the most important experiment I had ever taken part in in my life. And the next evening going home with them I had to swear them to secrecy.
Point-contact transistors were fragile and noisy. In early 1948, William Shockley came up with the idea of the semiconductor junction transistor. After a number of crucial steps, the first efficient working transistor of this type was announced in July 1951. The following appeared in 1952, in the monthly Electronic Engineer (London), vol. 24, p. 42:
Although it is unlikely that the transistor will ultimately displace the electronic valve, there is no doubt that for many electronic applications the transistor...will be preferred because of its robust and compact form.
Visit the relevant scholarly society (IXS).
Other API's, like VIM and MAPI, are expected to be Xapia-compliant once Xapia is finalized.
See also EFS and navel exercises discussions.
Why not BARA, CARA, ....? Because I thought the exes could use some bulking up, that's why.
XARA's are usually intentional, and AAP pleonasms are usually accidental, but see VS Sassoon.
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It's Greek to me.
The company that bought the rights to the process and developed it into a marketable product was Haloid, of Rochester, New York. They created the trademark Xerox in imitation of the name of its giant neighbor in Rochester, Kodak. (Kodak was one of the many companies that had turned down the chance to develop Carlson's patent.)
In 1949, Haloid introduced its first model and changed its name to Haloid Xerox. In 1959, Haloid Xerox introduced the Model 914, the first truly automatic model. They advertised it with a TV commercial in which a little girl makes a copy for her dad and then can't remember or tell which was the original and which was the copy. Many people watching the commercial couldn't believe the process was so automatic a girl could do it. Others did, and sales took off. In 1961, Haloid Xerox shortened its name to Xerox. The name Haloid is explained at the haloid entry.
W3.org offers an XHTML validation service.
I've seen this abbreviation a lot, but only on the internet. Then again, maybe I just don't have a nonvirtual life, so I would have no opportunity to see it elsewhere. In that case, I must be born again!
Xenon (Xe) is the heaviest non-radioactive noble gas. As such, it is about the densest gas at any given pressure. [Almost anything else that heavy would have stronger intermolecular forces, and would likely not be gaseous at the low temperatures reached in the shadowed (from the sun) regions of space.]
Why am I telling you this? Consider that you're using accelerated ions, of some sort, to propel a spacecraft. Say the ions have a mass m and that they are singly ionized (this is typical) so they have a charge e (that's q to electrical engineers), and that they are accelerated through a voltage V. Thus, each accelerated ion has an energy E = qV. This is kinetic energy for the ion, with velocity u and speed u = |u|:
1 2
- mu = E .
2
Hence, the impulse received by the ion -- the change in its momentum, equal
to the time integral of the force on it, is I = sqrt(2mE). The impulse that this exerts on the
spacecraft is equal (and opposite in direction). In other words, for a given
energy or voltage used, the impulse received by the satellite is proportional
to the square root of the ion mass. This simply represents the well-known
and intuitive fact that recoil from a heavy object is greater than from a
light one.
The analysis is simplest in terms of momentum or impulse: by Newton's third law, the forces that spacecraft and ion exert on each other are equal and opposite, and -- classically -- they act over the same time, so the impulses are equal and opposite. Thus, in order to get the most momentum bang for the energy buck, you want to use the most massive ions possible.
(Relativistically, momentum is also conserved, but in a typical reference frame the force durations are not equal. This is compensated by the fact that the forces are not equal either.) The kinetic energy changes of spacecraft and ion are not equal (in the center-of-mass frame), because the work done on each object is the distance integral of the force, and the distances traveled by the objects are different. Again, however, heavier ions produce a greater recoil, so for the same force they produce a greater recoil (i.e. acceleration) of the spacecraft.
Practices vary. In Spain and Italy, children traditionally receive gifts on the Day of the Magi, though Saint Nick is evangelizing furiously there. A relevant Christmas story can be found at the Martinmas entry.
XML is closely related to HTML and SGML and assumes a very similar, but not identical syntax. One difference: in XML one cannot omit end tags. Tags for elements which don't have any content are specially marked by a slash before the closing angle bracket. Also, properly speaking, XML (like SGML) is a meta-markup language -- a set of guidelines for how markup rules should be defined. Within XML, one defines domain-specific markup languages using document type definitions (DTD's).
What, that isn't enough information to just tucker you out? Okay then, try Jon Bosak: XML, Java, and the future of the Web.
Nowadays, XNS has been adopted/defined/accepted as an ISO protocol for Xerox LAN's.
The binary XOR operation is defined to be true if precisely one of the inputs is true, and false otherwise. It is evident (by enumeration of cases) that this XOR operation is associative, and it's obvious that it's commutative. Given these two properties, it follows that one may define the XOR of a collection of operands, irrespective of order (of the operations or the operands) in the same way that one defines the sum of a collection of numbers, given the associativity and commutativity of the binary sum (addition) operation.
In general, the XOR of a set of operands is true if the number of true operands is odd, and false otherwise.
Xeroderma means dry skin, but this is the disease whose sufferers are mortally sensitive to sunlight. XP is a rare genetic disease (150 children in the US are diagnosed with it) that destroys DNA's ability to self-repair. Severe burns as a result of brief UV exposure are the first symptom, typically occuring in the first months. In about twenty percent of cases, there is increased risk of neurological symptoms. Read more here.
Here's some instructional material from Virginia Tech (VT). Here's some from Charles Evans & Associates.
The Department of Physics at Uppsala University in Sweden has made available an X-Ray WWW Server.
When Madonna was known as Madonna Ciccone, and in high school in Michigan, she wore flesh-tone panties under her (own) cheerleader's uniform.
Madonna is younger than I, yet she is already much better known. I can deny it no longer: I am a failure.
Here's some instructional material from Virginia Tech.
Another application of X-ray lithography occurs in the fabrication of nanostructures. Specifically, the X-ray beam is split into a pair of aligned beams, projecting a diffraction pattern on the surface of the resist. Exposure and development produce a lattice pattern over a wide area with a pitch of as little as 1000 Å (0.1 µm).
An alternative approach, not evidently very efficient, would be to use a focused the X-ray beam. The problem with that is making an X-ray lens. Recently [reported in 1996.11.7 issue of Nature], Dr. Anatoly Snigirev and his wife Dr. Irina Snigireva developed a new lens for X-rays, and demonstated a submicron focal diameter. The new lens works somewhat like a quadrupole magnet in electron beam focusing: individual lenses create a divergence in one direction and a convergence in the perpendicular direction. Successive lenses oriented in different directions produce a net focusing in both lateral directions. An individual lens consists of an aluminum block, with a plane of parallel holes drilled in from the side.
Measurement of X-ray intensity along the undiffracted (i.e. specularly reflected) direction. Angle-dependent intensity changes arise from characteristics of surface roughness and from interlayer interference, and so angle dependence is used to measure surface roughness and layer thickness.
The name is a bit of a misdirection. The idea is that the incident and Bragg-reflected X-rays set up a standing-wave pattern throughout the region penetrated by the X-rays, and above it. A surface technique such as Auger (AES) or fluorescence spectroscopy (EDX) is then used to monitor the surface as the standing-wave pattern is varied by changing the angle of the sample relative to the incident X-ray beam.
Here's a particularly bad case of unreplaced exes that was published in the Chicago Sun-Times on July 15, 1997, pg. 6 of the main news section (Tuesday, Late Sports Final Edition):
Verneal Jimerson (above) and Dennis Williams (left) were two of the Four Heights Four convicted of xxxxx in 19xx. They were freed in 1996.[skip a paragraph]
Joseph Burroughs: convicted in 19XX for the robbery-murder of a Downstate man; cleared in 19XX.
The Boston Globe on Bastille Day 1996 had an article on the Reform party US presidential nomination that described presidential hopeful Richard Lamm as ``the Democratic governor of Colorado from 19xx to 19xx.''
The Washington Post, on April 27, 1994, gave the publication information for Dorian Leigh Parker's Doughnuts: Over 3 Dozen Crullers, Fritters and Other Treats as ``(Clarkson Potter, 19xx, $11).'' Highlights include Sour Cream Doughnuts, Snail Buns and Potato Doughnuts.
The Times-Picayune (New Orleans) on June 11, 2000
television guide had a review of a TBS made-for-TV
movie called ``On Hostile Ground.'' It's about a sinkhole that collapses the
French Quarter during Carnival. The salvation of the city is some kind of
miraculous polyurethane mixture, according to a heroic geologist named XXX Andrews (John Corbett). Also,
the rerun movie ``Superdome'' is glossed as (ABC, 19XX).
For a variety of applications, it is useful to have a template that one fills in, replacing text like ``Headline goes here,'' ``Caption goes here,'' and ``(Source here)'' as illustrated in the screen capture at right. When the news is hot, you may see stuff like this posted on a website.
A store-and-forward message-handling system (MHS) with graphics and fax capabilities. You know: attachments.
Servers that interrogate X.500 directories can be found here. A bit more information is available on the German-language version.