DB, db

DataBase.

DB

DayBook. A book in which daily transactions are recorded, or a diary. A lot of dictionaries that don't mention really common meanings of DB like Defensive Back do mention daybook. Okay, whatever.

dB, db

DeciBel. Ten times the common logarithm of a power ratio or twenty times the logarithm of a voltage ratio. E.g., 3 dB is a power ratio of two (3.0103 dB, to be more precise than is ever called for in practice, so far as I have ever experienced). A frequency where gain or transmission falls to half its maximum value is often called a ``3 dB point.'' Typically, the ratio is to an implicit power level (as in dBm, dB SPL, and dBu).

Pronunciation Sidebar

Note that most unit abbreviations are expanded in speech. For example, in. is pronounced ``inch,'' kg and kG as ``kilogram'' and ``kilogauss.'' [The latter example partly explains the practice.] There are a few exceptions, however: cc is read off as ``cee-cee'' and less often as ``cubic centimeter,'' and dB (especially in the jargon ``3 dB point'') is often pronounced ``dee-bee.''

Another example of anomalous unit abbreviation pronunciation is the ``mil'' pronunciation of the milliliter (ml) unit (but follow latter link for a surprise). Significantly, a milliliter is a fluid measure exactly equal in volume to a cubic centimeter. A dimensional resonance effect in phonological linguistics? The study of this and similar important issues in connection with unit names constructed by shortening the name of a hemieponymous honoree (amp from Ampere, torr from Torricelli, volt from Volta, etc.) could probably supply a few grad students with PhD dissertation topics.

Modern audio hardware typically references volume levels to a maximum, so most audio API's represent volume by a nonpositive number: a logarithmic attenuation factor. In the DirectSound, for example, volume ranges from -10000 to 0, in units of a hundredth of a decibel. I guess that ought to be millibels (mB). Note that when sound is digitized in 16 bits, the ratio of highest to lowest amplitude is 65536:1, or 320 log₁₀2 dB (about 96 dB). Cf. CD.

DB

Declining Balance. A declining-balance card is like a company-town debit card without the checks.

DB

Defensive Back. A position in American football. The term is also used generically for the whole secondary. I'll write more when I figure out what that means.

Strength is more important in defensive linemen than in other defensive positions; speed is more important in DB's, DE's, and safeties than in DL's. That ``speed,'' however, is primarily sprint speed. The nonfootball stat that is the significant figure of merit for DL's is time in the 40-yard dash. No one is interested in their 1000-meter or marathon times.

Those sorts of facts were called immediately to mind by football news reported by the AP for Thursday, April 3, 2008. Around 11:30 AM, there was a disturbance in the parking lot of the police station, no less, in Pearland, Texas (about 15 mi. south of Houston). When officers approached to investigate, Kenny Wright, a DB with the Cleveland Browns, took off running. Police said he led them on a quarter-mile foot race, but no precise times were reported. Sgt. Roy Castillo said in a statement that ``we had people on scene pretty fast and I believe because of our quick response time and the mental and physical toughness of our officers to catch offenders, we were able to get him in custody quickly and safely.''

The defensive back was eventually tackled at a nearby subdivision. That's fair: he had possession -- at least of marijuana in his car, allegedly. And if he didn't have possession maybe he was going for it, so you could say he was intercepted. He was held in the Pearland City Jail that night on various misdemeanor charges, pending a bond hearing Friday. Wright attended Northwestern State in Louisiana. He graduated magna cum laude... oh wait, that must be someone else. He went to the Minnesota Vikings in the fourth round of the 1999 draft. The nine-year veteran has also played for Houston, Jacksonville, and Washington. He has seven career interceptions of his own. He had a disappointing season in 2007, and he was released by the Browns in July 2008.

DB

Degree of Branching. Term typically used in discussion of organic polymers.

DB

Deutsch-Bonnet. Charles Deutch and René Bonnet formed a partnership to build sports cars that were known as DB's. They were renowned in the 1950's and 1960's for their unusual (but aerodynamically small) bodies and for their small engines (under one liter). ``DBs won the coveted Index of Performance several times in the world's most prestigious endurance races.'' (This according to the brochure for an ``Art of the National Sports Car'' exhibit at Notre Dame's Snite Museum of Art, Summer 2004.

DB

Dial Box. Phone instrument from the steam age.

For another kind of Dial box, see the BOGO entry.

DB

Dielectric Breakdown. The dielectric in question is usually functioning principally as an insulator, with the value of its dielectric constant a secondary consideration. Therefore, change of n is not the issue in DB, it's the occurrence of conductivity.

DB

Doomsday Book. Or Domesday Book. Those Normans may have been effective conquerors, but they couldn't spell.

Db

Dubnium. Atomic number 105. Learn more at its entry in WebElements and its entry at Chemicool.

DBA

DataBase Administrator.

DBA

DihydroDimethylbenzopyranButyric Acid.

DBA

Doctor[ate] {of|in} Business Administration. A doctor who administers the business instead of the medicine. Also the degree qualifying a person to do such a thing. Not to be confused with the traditional business-related DBA...

DBA, dba, d/b/a

Doing Business As.

On my most recent trip itinerary (the one printed out on the green computer cards) I was surprised to see the actual name of the regional feeder that code-shares with ATA (the airline I took), followed by ``DBA ATA Express.''

D-Backs

DiamondBACKS. Arizona professional baseball team. The diamondback is a desert snake.

DBAG

Deutsche Bundesbahnen AG. Old name of the German (.de) national railways. Sorry, I don't know the new name.

DBAli

DataBase of (protein) sequence and structure ALIgnments. Announced by Marc A. Marti-Renom, Valentin A. Ilyin, and Andrej Sali in Bioinformatics, vol. 17, #8 (August 2001), pp. 746-747. Maybe there's a URL, but I don't know. I only saw the abstract while searching for papers on guitar acoustics. This paper was one of the search results, evidently because the abstract mentions Ilyin and Sali's ModView at <http://guitar.rockefeller.edu/>. Oh look -- from that page there are links to various bioinformatics resources of the Sali lab, including one to DBAli.

As you will have noticed, this glossary is so up-to-the-CPU-cycle that you see the new entries in the jumbled form they take as the news is breaking. You also see the old entries that way. We strive for the genuine appearance of authenticity.

I can remember when those heavy oversize citation and periodical indices would lie heavy in my lap, as I used pencil-and-paper technology to record which articles I needed while my legs fell asleep on the library carpeting. So I don't complain about a few inappropriate extra hits on my search (beta error). Not too long after I learn what it is, we'll have an entry for the guitar nebula, too.

DBAN

DiBromoAcetoNitrile. Other haloacetonitriles popular in water treatment are BCAN, CAN, DCAN, and TCAN.

DBB

Deutscher Beamtenbund. German Public Servants' Union, with 1.12 million members in 1997 (330 thousand female). The largest union outside the DGB, q.v.

DBCP

DiBromoChloroPropane.

DBCS

Double-Byte Character Set. A term used for various pre-Unicode character encodings that used two-byte encodings only for some characters (albeit for most of them, in fact) and single-byte encodings for others. The idea was to allow compatibility with pure-ASCII systems where possible. See ``Internationalization and Character Set Standards'' in ACM Journal of Standards, pp. 31-39 (September 1993).

DBD

Dead-Burned Dolomite. Calcined dolomitic limestone.

DBDDD

Division of Birth Defects and Developmental Disabilities. An NCEH division that has been promoted to a national center of its own -- NCBDDD. Also abbreviated BDDD.

DBF

Discrete Block Format. Sector formatting for optical disc memory.

DBFK, DBfK

Deutscher Berufsverband für Krankenpflege. Earlier name of the organization whose name was and is typically translated as `German Nurses Association.' A more precise translation would be `German Professional Association for Nursing,' where ``German,'' of course, modifies ``Association.'' The word Pflege alone can mean `nursing' in the medical sense, but the verb pflegen means `take care of' in other senses as well, including `groom,' `manicure,' `cultivate,' `attend to,' etc. Attachment of Kranken ([weak-form] genitive of `sick person, patient, invalid') yields a narrower term.

At some point, the organization evidently came to feel that the term was too narrow. As of early 2010, DBfK's webpage explains that the DBfK ``ist die Interessenvertretung von Beschäftigten und Selbständigen der Gesundheits- und Krankenpflege, der Gesundheits- und Kinderkrankenpflege und der Altenpflege.'' Roughly, it `is the group representing the interests of those employed and self-employed in health care and nursing, children's health care and nursing, and old-age care.' I am grateful that they phrased this using Pflege rather than Pflegerinnen und Pfleger (`female and male nurses').

The first compound noun in the name is Berufsverband. Beruf is `profession.' (A bit more literally, it's `calling.' You profess what you are called to.) As Krankenpflege was evidently deemed to make the earlier name too narrow, the name was changed to Der Deutsche Berufsverband für Pflegeberufe. The last word means `nursing professions' or even `caring professions,' if you like that sort of term. The acronym was then sealed, and in the usual way the organization styles itself along the lines of ``DBfK -- Deutscher Berufsverband für Pflegeberufe.'' (The DBfK itself seems to prefer the lower-case-f form of the acronym, but the all-caps form seems to dominate.)

DBFN

The Dick Butkus Football Network.

D.B.H.

Diameter Breast Height. The diameter (normally of a tree) measured at ``breast height'' -- 4.5 feet. For more of this, but without the trees, see the bra size mathematics entry.

DBI

DataBase Interface. It rhymes -- and it means something.

DBI

Deutschen Bibliotheksinstitut.

DBI

DuBois Institute. Established at Clark Atlanta University (CAU) with funding from the Andrew Mellon Foundation. CAU was created in 1988 from the merger of Clark College and Atlanta University. Atlanta University was the institutional home of W.E.B. DuBois for many years, and from 1895 Atlanta University was a major venue for research and conferences on the condition of blacks in the US.

See also DBI's sister institution SCSPP.

dBm

DeciBel Milliwatts. (0 dBm = 1 mW, 30 dBm = 1 W.)

DBM

Deterministic Boltzmann Machine.

DBM

DiamondBack Moth. (Plutella xylostella.)

dB Magazine

UCLA Daily Bruin Arts and Entertainment MAGAZINE.

DBMM

DataBase MisManager.

DBMS

DataBase Management System. Also: RDBMS (relational) and DDBMS (distributed).

DBN

De-Bottle-Necking. Like, removing bottle-necks, I think. See this used in sentence by FFC at this page.

DBN

Dial-Back Number.

DBP

DiButyl Phosphate.

DBP

DiButyl Phthalate. A plasticizer. Human flesh is a (very co-) polymer which mostly uses water as a plasticizer.

DBP

Disinfection By-Product.

DBPL

DataBase Programming Language. Also the name of a particular DBPL (gzipped PS here) based on Modula-2 (the official successor of Pascal, which was proposed to point a way for Algol).

DBR

Distributed Bragg Reflect{ion|or}. In VCSEL's, the endcap mirrors. Made by finite periodic structures that have a stop band (SB) (optical speak for band gap) in wavelength range of interest.

dBrn

DeciBel Relative to Noise.

dBrnc

DeciBel Relative to Noise (C-notch or C-message).

DBS

DataBase Server.

DBS

DataBase System.

DBS, D.B.S.

Deep Brain Stimulation. A therapeutic procedure for Parkinson's disease, approved in the US in 2002 or so. An electrode is implanted in the brain (usually in either the thalamus, the globus pallidus internus, or the subthalamic nucleus [STN]). Brief electric pulses (usually in a rectangular pulse pattern) delivered by the electrode can control tremors in many patients. (Failing that, they may at least reduce the amount of medication patients have to take. Parkinson's has a broad menu of symptoms which manifest in various combinations and degrees.)

DBS has been been proposed and tried for a variety of other ailments, including depression, OCD, and Tourette's syndrome. In each case, a different set of brain regions is targeted.

Batteries included! Implanted in your chest, typically, with wires running subcutaneously along the side of the neck and up to the brain. Nowadays these batteries are usually rechargeable, so surgery to replace them is infrequent. There are many different designs and implementations. Some alternative approaches involve an external battery driving a radio transmitter, and a receiving-antenna coil over the site of the brain implant.

When an implanted power supply is used, however, there may be antennas also: pulse generation, which has to be adjusted to the patient's response, is often controlled via radio communication with an external programmer or controller. (Pulse generation also has to be turned on. The surgery to implant the electrodes may provide about a month's worth of stimulation; normally, pulse generation isn't turned on until that initial stimulatory effect has worn off.)

DBS

Double Barrier Structure.

DBS

Direct Binary Search. Vide M. A. Seldowitz, J. P. Allebach, and D. W. Sweeney, ``Synthesis of digital holograms by direct binary search,'' Applied Optics 26, pp. 2788-2798 (1987).

DBS

Direct (TV) Broadcast Satellite. Satellites with high power (~100 W per channel), for transmission of radio and TV signals that can be received by small dishes owned by individual end users.

By FCC dictamination, DBS satellites broadcasting in the same band are (in geostationary orbit -- GEO) spaced 9 degrees of longitude apart rather than the conventional 2°, in order to allow small dishes (say 16" or 18") to pick up the signal without interference.

DBS is one of the two classes of ``consumer satellites.'' The other is Medium-Powered Satellite (MPS).

Current usage makes DBS synonymous with any satellites used for direct-to-home (DTH) transmission. That is, DBS as defined by the FCC is conflated with satellite TV delivered to end-users via ordinary satellites on the regular bands. This typically requires 36-40" dishes.

dB SPL

DeciBel Sound Pressure Level, defined so that 0 db SPL = 20×10^-5 N/m² = 200 pbar, a pressure level that is something like the best human sensitivity at 1 kHz. A typical human hearing threshold is 20 db SPL; sensitivity is about 5 db better at about 3 kHz.)

However, on VU meters and other audio indicators, the label ``0 dB'' indicates where a particular amplifier and typical tape head driver start saturating the amp. Record below 0 to avoid distortion (and conversely).

DBT

Dialectical Behavior Therapy. Sounds like something out of the Gulag, but it was developed in the West as a therapy for BPD. Don't twist your tongue. One good thing about the DBT initialism is that it helps you avoid accidentally calling it diabolical behavior therapy.

dBu

DeciBel normalization used in telephony: on a 600-ohm line, 1 mW was 0.775 V. When dB are used to indicate power (through voltage) in that way, regardless of impedance, this unit is used. Also called ``audio dBm.'' ``Radio dBm'' is referenced to a 50-ohm line (0.22 V is 0 dB). Actual usage gets even stranger.

dBW

DeciBel normalized to one watt (W). So 0 dBW is one watt of power, and 3 dBW is 2 W, etc.

DBX

Digital (private) Branch eXchange (PBX).

DB6

HEXylphenyl CyanoBenzoyloxy benzoate.

D & C

Democrat and Chronicle. A Gannett-chain newspaper in Rochester, N.Y.

D.C.

Depois de Cristo (Portuguese) or Después de Cristo (Spanish). `After Christ' -- used in dates as A.D. is used in English. Cf. A.C.

dc

Desk Calculator. A reverse-Polish desk calculator which supports ``unlimited-precision'' arithmetic. It's an old gnu utility. Actually, it's an old Unix utility, but that doesn't make much of a pun, does it?

Originally, bc was a preprocessor for dc. But we haven't figured out what bc stands for, so we can't tell you anything about it. Except that it's practically a baby-C-like calculator programming language. Maybe it stands for Big Honkin' Calculator? Nope -- no aitch.

DC

Developing Country. The acronym could as easily stand for Developed Countries, so LDC is preferable.

DC

Dietitians of Canada. The Canadian ICDA member.

DC

Diététistes du Canada. Wait a second -- that's the same abbreviation as in English. I'm going to have to rest a while and try to figure out how this could have happened.

D & C

Dilatation and Curettage. I really don't think we need to explain that here. A curette is a spoon-shaped scraper.

DC

Diners Club. A credit card.

dc, DC, D.C., d.c., D.-C., d.-c.

Direct Current. The forms with periods are old and out of fashion. In the better electronics books that were published before television and widespread illiteracy in the professional classes, you would see a consistent distinction between D.C. and D.-C. D.C. was the abbreviation of the compound noun and sometimes for the predicate adjective (substituting for direct current in, for example, ``direct current flows'' and ``power supply is direct current''). The hyphenated form was used for ordinary adjectives, as in ``D.-C. motor.'' The reason for the hyphen was straightforward: when a compound noun functions attributively -- i.e., as an adjective -- a hyphen is used to make clear that the noun one first encounters in reading is not functioning as a noun in the larger context of the noun phrase. This is discussed further in the attributive noun entry. Similar remarks apply to the use of A.C., A.-C., etc.

The fact is that nowadays, dc, DC, etc., always stand for the adjective. If you want to express the substantive ``direct current'' in fewer than thirteen characters, you can use the AAP pleonasm ``DC current.''

You needed to know this. If you want to know something, uh, substantive about direct current in electronics, you should see the Alternating Current entry.

DC, D.C.

District of Columbia. USPS abbreviation always omits periods.

The Villanova University Law School provides some links to state government web sites for DC. USACityLink.com has a page of District links.

The federal district for the US capital. ``Washington, D.C.,'' is all of the D.C. there is; there's no ``Foobar, D.C.'' where Foobar has any value other than Washington. Once upon a time, however, Washington was the name for only one section of the district.

Cf. D.F.

DCA

Debt Counselors of America. A nonprofit group that helps people climb out of holes.

``If you're going through some difficult financial times right now, don't give up. Being deep in debt is not fun. It's scary and frightening but you can survive. The panic attacks, waking up in the middle of the night, and constant stress will begin to vanish once you take a positive step towards getting out of debt. There is hope, we can help.''

DCA

DiChloroAcetic acid.

DC, D.C.

Doctor of Chiropractic. Chiropractic is a noun as well as an adjective. Originally, chiropractic was based on an acupuncture-like theory of disease and made outlandish claims about the possibility of curing a range of ailments by manipulation of the spine. The Latin root man- for hand appears in the word manipulate (for more see the mano a mano entry); the Greek root for hand, chiro-, was used in constructing chiropractic.

Since its establishment, chiropractic has tried and succeeded somewhat in cleaning up its act -- toning down its more preposterous claims, scrounging up some scientifically sound clinical research support for its claims of efficacy. A couple of people I know regularly visit chiropractors.

Chiropractic is a lot like a major religion: at first, it won converts at least partly on the basis of a salvific wish-fulfillment fantasy so preposterous it could only be accepted on faith. (As Augustine the Saint wrote, he believed because it was absurd.) Once it had a number of regular communicants, it amended the message. If people were rational, the jettison of initially central claims might lead them to question the epistemic basis of the remaining rationalizations. People are not rational, and they go on believing. ``Judge the tree by its fruit,'' they say. One of my friends who goes to a chiropractor told him to ``stop doing the neck'' after that professional did a number on it.

By the way, you shouldn't take this the wrong way: when I make fun of religion, I'm making fun of someone else's religion. Your religion is very reasonable.

DCA

IATA abbreviation for ``National Airport,'' serving Washington, DC. Congress renamed it ``Ronald Reagan Washington National Airport.''

DCA

Digital Communications Associates.

DCA

Direct Chip Attach[ment]. Bare integrated circuit chip is placed directly on printed wiring board (PWB).

DCAN

DiChloroAcetoNitrile. Other haloacetonitriles popular in water treatment are BCAN, CAN, DBAN, and TCAN.

DCB

Database of Classical Bibliography. A CD-ROM and custom (Ancient-Greek-capable) search software that features l'Année Philologique (APh) and includes other databases as well. DCB's contract with SIBC requires that the most recent APh volume included in the DCB discs remain three years behind the most recent print APh volume. That's pretty sad, because the APh itself is pretty far behind. It's no imposition, though, since DCB is more than three years behind, and they're ``sold out'' as of May 2000. (However, the DCB webpages are never updated, so the situation may be a little better than advertised on the web.)

Man, you'd be surprised at all the resentment seething under the calm urbane surface of your ordinary classicist.

The DCB-CD version 2 (the one that's sold out) contains 248,399 bibliographical records from sixteen volumes of APh (vols. 45-60 covering 1974-1989). It comes equipped with its own retrieval software for both Windows and Macintosh platforms, with user-selectable English or French interfaces.

Classicists lean disproportionately toward Macs rather than Windows machines (though I don't think Classics is majority-Mac any more). This probably had something to do with the early character-set flexibility of the Macs, while PC's still had nothing but ``IBM Character Set.'' Among the humanistic disciplines, Classics was an early adopter of computer technology.

DCB

Data Control Block.

DCB

Double Cantilever Beam. The DCB test is widely used to characterize the mode-I delamination and bridging behavior of laminated continuous-fiber composite materials.

DCC

Data Communications Channel.

DCC

Data Country Code.

DCC

Departmental Computer Consultant.

DCC

Digital Compact Cassette.

DCC

Digital Cross Connect (system). Explanation at DXC.

DCC

Distributed Computing Consultants at UB.

DCc, DCC

Double ConCave. Less ambiguous and less common than the abbreviation DCV.

DCC

Double Concave Cone (lens). See the article by Keizo Kono, Mitsuru Irie, and Takumi Minemoto, ``Generation of Nearly Diffraction-Free Beams Using a New Optical System,'' Optical Review, vol. 4, #3 (1997), pp. 423-428.

DCC

Dual Constant Composition.

DCCC

Democratic (US political party) Congressional Campaign Committee. Some call it the ``Dee-triple-Cee.'' Officially neutral in primaries, in 1998 it was especially heavy-handed in offing mainstream Democratic primary candidates for ``contested'' seats, in favor of conservatives who can help them regain control of Congress. Harvest the whirlwind.

The corresponding Democratic Senate group is DSCC. The Republican House group analogous to the DCCC is the NRCC (National Republican Congressional Committee).

Fast-forward to 2001. Funny how things turn out.

DCCCD

Dallas County Community College District.

DCCN

Dimensions of Critical Care Nursing. The editor in chief is Vickie A. Miracle, RN, EdD, CCRN, CCNS, CCRC. how did she get all those letters after her name? That's, that's just... that's just amazing!

DCD

Data Carrier Detect.

DCD

Disk CaDd{y|ies}.

DC/DC converter

A circuit that converts a DC voltage into a larger DC voltage, typically by chopping it into AC and transforming that. Check with Power Convertibles Corp..

DCE

Data Communication[s] Equipment. Most often, this refers to the data circuit-terminating equipment (e.g., a modem or printer) that interfaces to one side with the DTE and to a communication channel (e.g., telephone line) on the other.

DCE

Distributed Computing Environment. Here's some stuff on the DCE project at UB.

DCF

Dénomination Commune Français. Official French generic drug name.

DCFL

Direct-Coupled FET Logic. Logic family using both depletion-mode and enhancement-mode MESFET's (or HEMT's). Very similar to NMOS logic with depletion-mode active loads. Requires more accurate threshold-voltage tuning than pure d-mode FET logics.

DCFMA

Don't Cry For Me Argentina (.ar).

DCG

Derived (environmental contaminant) Concentration Guideline[s].

DCG

DiChromated Gelatin. Highly photorefractive material, for holography.

DCHEMT

Doped-Channel High Electron Mobility Transistor (HEMT).

DCHT

Dual-channel Heterostructure (Field-effect) Transistor (Dual-channel) ``HFET''. Can function as a velocity-modulated transistor.

DCI

Desktop Color Imaging.

DCI

Direct-Current Ionization. In some applications, this is called ``frying.''

DCI

Director of Central Intelligence. Head of the CIA.

DCIVC

Discovery Civilizations. A cable TV channel available (starting in 2002) in Canada. (That's the ``C.'') Scheduling and content of cable channels often don't quite match up between US and Canadian distributions. As of August 2002, the schedules of the Canadian version aren't being made available, but they do seem to coincide with DCIVU.

DCIVU

Discovery Civilizations. A cable TV channel, US version. See AWOTV for programming relevant to the ancient world.

DCL

Data Control Language.

DCL

Delay Calculator Language for chip timing design.

DCL

Detection, Classification and Localization. Target acquisition talk.

DCL

Digital { Control | Command } Language. System control language for Digital Equipment Corporation mainframe.

DCL PI

Delay Calculator Language Procedural Interface.

DCM

DiChloroMethane.

DCO

DC Out(put).

DCP

Défenses Civiles Populaires.

DCP

DiChloroPhenol.

DCP

Direct-Current Plasma.

DCP

Distributed Collaborative Planning.

DCPA

Denver Center for the Performing Arts.

DCPAES

Direct-Current Plasma (DCP) Atomic Emission Spectroscopy (AES).

Not the Denver Center for the Performing Arts (DCPA) Electron Spectroscopy (ES).

DCPS

District of Columbia Public Schools.

DCPSK

Differential Coherent Phase-Shift Keying.

DCR

Design Change Request. How dare you! Again!

DCR

Digital Cable Radio.

DCR, DC&R

Diseases of the Colon & Rectum. A journal. The masochist's ideal bathroom reader. Also the official journal of ASCRS.

DCS

DiChloroSilane.

DCS 1800

Digital Cellular Standard for 1800 MHz band. A GSM-compliant standard first implemented as a pan-European standard, starting in 1990, to replace the panoply of existing national and regional standards that were implemented in the 80's. It's experienced phenomenal growth.

DCS

Digital Cross-connect (DCC) System. Following a more systematic naming pattern, it's also called DSX. Explanation at DXC.

DCT

Discrete Cosine Transform.

DCTC

Denver Center Theatre Company. A producing division of the DCPA.

DCTC

Directors' Choice Theater Company. Live theater for the Washington, D.C.-Baltimore area.

DCTL

Direct-coupled Transistor Logic. The logic family is long obsolete, but the philosophy behind it evolved into I²L, which is also dead. I don't know if any Schottky I²L is used commercially.

DCU

Data Cache Unit.

DCV

Double ConcaVe (lens). A lens with two inward-curving faces and a negative focal length, used to form a reduced image or to spread a light beam. Cf. PCV, DCX.

DCVD

Dielectric Chemical Vapor Deposition (CVD). That's the deposition of dielectric films, not deposition by dielectric, particularly.

DCVMA

District of Columbia Veterinary Medical Association. See also AVMA.

DCX

Double Charge eXchange.

DCX

Double ConveX (lens). A lens with two outward-curving faces and a positive focal length, used to magnify an image or as a condensing lens (i.e., to concentrate a light beam). Cf. PCX, DCV.

DCYSC

Discovery Channel Young Scientist Challenge. A science contest for students in grades 5 through 8. Each year, a number of ``finalists'' are chosen from among students who compete in regional science and engineering fairs affiliated with Science Service in US states and territories (there's no regional quota or allocation, it appears). Top prizes are scholarships, and there are large numbers of smaller prizes like tee shirts.

DD

Data Definition. In IBM JCL, A DD card or statement describes the attributes of a data set or file, and every data set or file used by an application code requires a DD statement.

DD is part of the Unix children's alphabet poem (alternate locations: 1, 2, 3, 4).

.
.
.
C is for CC, as hackers recall, while
D is for DD, the command that does all.

E is for Emacs, which rebinds your keys, and
F is for Fsck, which rebuilds your trees.
.
.
.

By some metric that weights opacity and frequency multiplicatively, the worst statement in IBM JCL is //SYSIN DD *. The // means that a JCL statement follows, SYSIN is a system logical name (all DD statements begin with such a statement label, which identifies just which data are being defined. The * means that control cards follow. To the tune of ``Camp-town Races,'' the approved way to read this card is ``Slash Slash Sysin Dee-Dee Star, Doo-dah, Doo-dah.''

D & D

Decontamination and Decommissioning.

DD

Depacketization Delay.

DD

Disthymic Disorder. Sad, but not so sad.

DD

Doctoral Dissertation.

DD

Doctor of Divinity.

In fall 1998, the dean of Harvard Divinity School was forced to resign after thousands of pornographic images were found on his Harvard-owned personal computer. (This was only revealed the following May; so he could find another job, maybe?)

The pornographic material was found on the office computer at his Harvard-owned residence at Jewett House. The discovery was made after Thiemann requested more disk space for one of his Harvard-owned machines, which was full, according to university sources. He actually asked the computer department to transfer the pornographic files to the new disk drive, according to sources that should probably be admired for not breaking up laughing.

Cf. mv, tar, JPEG.

DD

Domain Decomposition. This isn't as rotten as it sounds.

DD

Double-Dee. Next brassiere cup size after D. Cf. AA.

Normally, when a head term has two or more entries, I try to order the entries by alphabetical order of definitions or expansions, but not this time. I mean really, if you know the where to look for the definition, you probably already know the definition anyway, and you're just reading this glossary for your own perverted purposes, like sordid entertainment, and slowing down the server for people who need it for serious research. Shame!

DD

Double Density (floppy disk). This designation is preferred for 3½'' because all 3.5 diskettes are double-sided; the older-style, larger-diameter diskettes take the designation (DSDD: Double-Sided DD) because the first ones were one-sided. [No, they were not Möbius discs, they were only supposed to be recorded on one side. At some point, after two-sided disks became available, someone realized that the cheaper one-sideds could be recorded on both sides -- it was cheaper to manufacture just one type.

DD 3.5 diskettes hold only about 800Kbytes of data apiece. If you have an old computer that expects DD, you can still insert HD diskettes and they should work. DD diskettes are recognizable from the single notch (on extreme left corner of illustration at right) with a sliding cover (open or missing cover for write protection, closed to enable writing; if you lost the slide, cover with opaque tape). If you have a drive that recognizes HD diskettes, but have written at DD on another machine, or want to write in DD format to be read by another machine, then cover the extra hole (no sliding cover) on the other side.

DD

Double Diffusion.

DD

Drift-Diffusion (model[ing]).

D&D, d+d

Drug and Disease. Personals-ad usage, as in ``D&D-free.''

D & D

Dungeons and Dragons. Highly involved role-playing games (RPG's), popular among college students. Rules and roles made up and sometimes stated by a dungeon master (DM).

DD

HTML mark-up tag (in angle brackets: <DD>) for the definition part of a definition-list entry. Hence, for example, the mark-up for this entry reads:

<DT>DD<A NAME="DDhtml"> </A>
<DD><A HREF="H.html#HTML">HTML</A> mark-up tag
(in angle brackets: &lt;DD&gt;) for the
definition part of a definition-list entry.  Hence, for example,
the mark-up for this entry reads:
<P>
<PRE>
&lt;DT&gt;DD&lt;A NAME=&quot;DDhtml&quot;&gt; &lt;/A&gt;
&lt;DD&gt;&lt;A HREF=&quot;H.html#HTML&quot;&gt;HTML&lt;/A&gt; mark-up tag
(in angle brackets: &amp;lt;DD&amp;gt;) for the
definition part of a definition-list entry.  Hence, for example,
the mark-up for this entry reads:
&lt;P&gt;
</PRE>

Uhhh, etc.

DDA

Dial-on-Demand Access. A service of routers (available in Cisco IOS) used for two purposes:

1. Dial backup (or dial back-up): Automatic reestablishment of connectivity by an alternate path when there is a disruption in the primary connection (modem or DSU/CSU failure, mice eating the insulation, etc.). ``Dial'' is used loosely here: the connection may be over various kinds of network.
2. Dynamic bandwidth: Use of the dial backup techniques to add bandwidth as needed. Need is usually determined by simple algorithm: exceeding a high bandwidth-utilization level for a predetermined minimum time triggers bandwidth expansion, falling below a low bandwidth-utilization level for a given time triggers scale-back.

Cf. DDR.

DDA

Digital Differential Analyzer.

DDA

Directed Duty Assignment.

DDA

Dispensing Doctors' Association. An association ``[r]epresenting family doctors in primary care in the UK who dispense medications for patients.''

DDAF

Doris Day Animal Foundation. Home of ``Spay Day USA.'' Which Day was that?!

DDAL

Doris Day Animal League.

D. Day

Doris Day. Born Doris Mary Ann Von Kappelhoff, April 3, 1928. This Dee Dee was a sort of department-store Bee Bee, the way French fashions in those days were quickly copied, with adjustments for a more modest style, in cheaper materials for the American mass market. After the days when she appealed to animal instincts, BB became an animal rights activist; DD did too, in the more modest American political fashion -- see DDAF, DDAL.

In a series of romantic comedy trifles in the fifties and sixties, she was often cast with a central-casting prune as a best friend, to establish contrast. It's been pointed out that in her films that she never had trouble finding a parking space, but is that so odd? If a character in a movie is going to have difficulty finding a parking space, it has to be written into the screenplay, and it ought to advance the story.

D-Day

The day of the Allied (mostly combined Anglophone) invasion of Normandy during WWII. Why D-Day and not A-Day or B-Day? Well, the action began at H-Hour...

Cf. Dee Day.

DDB

Device-Dependent Bitmap.

DDBMS

Distributed DataBase Management System.

D/DBPS

Disinfection and Disinfection By-Products.

ddC, DDC

DiDeoxyCytidine. An NRTI used in AIDS treatment. Roche's trademarked name for the drug is HIVID; the generic name is zalcitabine (written Zalcitabin in German).

DDC

Dewey Decimal Classification. A system (and it does tend to be called the ``Dewey Decimal System'') for classifying library and archival materials. It is more straightforwardly hierarchical than the LC system (the LCC), and tends to be more popular for smaller collections. It seems to be pretty standard for public-school libraries and for the public libraries of smaller cities. The original Dewey system, promulgated in 1876, was developed by an American librarian named Melvil Dewey (Dec. 10, 1851-Dec. 26, 1931). [One of the early (command-line and apparently curses-driven) OLCL's was called MELVIL. Now you know why.]

The Dewey system defines fewer than a thousand ``general fields of knowledge'' between 000 and 999, with decimal-fraction subdivisions. One of the striking things about Dewey's system is that all of English prose fiction is subsumed under a one or two of those ``general fields.'' I can't recall, but let's say it's 823. (If there are two then one is for American and one for other English-language prose fiction; I'll look into it.) If you look in a library that uses the Dewey system, you won't find many books there, even though (or rather because) very roughly half of the books in a public library are prose fiction. Most libraries that use the Dewey system split the collection into fiction and ``nonfiction'' (whatever isn't prose fiction, or prose fiction in English); they catalogue and shelve nonfiction according to Dewey, and fiction alphabetically (perhaps by Cutter numbers). Poetry is typically shelved with ``nonfiction.''

There are various other systems, though there is a trend toward standardization. Computerization of library catalogs has obviously facilitated this, and mobility has probably also reduced the tolerance of library patrons for idiosyncratic local systems. The change-over can be a problem, however. When I used the Princeton University libraries in the 1970's and 1980's, many books were still catalogued using the local Richardson Classification scheme. For most major subject categories in the Fine Hall Library (Physics and Math), there were newer books under LC numbers and older books under the Richardson numbers. This webpage of the OCLC lists 30 ``other'' classification schemes. Perhaps the most widely used decimal scheme on a global basis is the UDC, q.v. Another decimal scheme is the Dutch SISO.

Edition 22 of the Dewey system was rolled out in mid-2003 on a gurney. Well, it was stretched out, anyway. Four volumes; I hope they're shelved together. By the way, new editions don't just add more digits and subcategories, you know -- they sometimes reshelve books to different parts of the library. For example, 647.94 of Edition 21 (hotel directories -- ``interdisciplinary and descriptive'') became 910.46 in Edition 22. ``We anticipate this will be a welcome relocation because the descriptive literature on lodging (in contrast to the literature directed toward people maintaining the lodging) is almost exclusively of interest to travelers. Materials on household management in the hospitality industry, bed and breakfast establishments, hostels, hotels, inns, motels, resorts will remain at 647.94. Other relocations include interdisciplinary and descriptive works on resorts relocated to 910.462; on bed and breakfast establishments relocated to 910.464; on hostels relocated to 910.466; and on campsites relocated to 910.468. Interdisciplinary works on the hospitality industry have been relocated to 338.4791, and on tourism to 910. Facilities for travelers and lodging for travelers (including hotels, motels, etc.) in specific areas have been relocated from 647.943-647.949 to 913-919 together with the new notation 06 in the add table at 913-919.

Stay tuned for further exciting developments.

DDC

Direction du développement et de la coopération.

DDCSD

Dual Dielectric Charge Storage Device.

DDCMP

Digital Data Communications Message Protocol. (Associated with DNA.)

DDD

Dictionary of Deities and Demons in the Bible. It ``is in some ways unlike any other dictionary in the field of biblical studies. This is the first catalogue of its kind, one which discusses all the gods and demons whose names are found in the Bible. Complementing the usual surveys and histories of Mesopotamian, Egyptian, Ugaritic, Syro-Palestinian, Persian, Greek, and Roman religion, DDD assesses the impact of contemporary religions on Israel and the Early Church by focusing on those gods that actually left traces in the Bible.'' (Except as noted, quotes in this entry are taken from the Introduction.)

The ``traces'' are found in five groups:

1. Gods mentioned by name (as gods).
      ``Obvious examples include Asherah, Baal, El, Hermes, Zeus, and others. ... In some instances the names are found only in the Septuagint and not in the corresponding section of the Masoretic text.'' The example given in Jeremiah 46:15, which is ``éphugen ho Apis'' in the LXX (`[Why] has Apis fled?') where the Masoretic text has the single verb (I don't know the vowels) NSHP (`[Why] was it swept away?'). It's not especially clear what's going on here, but as usual (and not entirely without justification) the contrast is described as ``valuable'' information. Anyone could valuate it.


2. Gods whose names are etymons of theophoric anthroponyms and toponyms (that's personal and place names, okay?).
      It is conscientiously animadverted that the people of Anathoth cannot be assumed to worship Anat, and that Tychicus may not worship Tyche, etc., ``[y]et such names reflect a certain familiarity with the deities in question, if not of the inhabitants of the town or the bearer of the name, then at least of their ancestors or their surroundings.'' Well, yes, and they can call that ``part of the religious milieu of the Bible,'' but often I can call it insignificant.


3. ``Demythologized deities.''
      The common-noun category corresponding to the previous group of names. An interesting though trivial example: tirosh, the Hebrew word for `new wine,' is ``etymologically the equivalent of the Mesopotamian deity Sirish and the Canaanite god Tirash. Further, ``[o]ne of the Hebrew words for the moon used in the Bible is yareah; this is the etymological equivalent of Yarikh, the moon-god known from Ugaritic texts.'' Alas poor Yarikh. I'll spare you their extenuation for including notice of these words. They're being thorough, and I approve that.
      One may wonder, in cases like Yarikh, whether what is found is not a reversion to or a continuation of a nonreligious tradition. That is, that the originally nonmythological moon's name, for example, was drafted into mythological service. The goddess of the dawn is Eos in Greek and Aurora in Latin. It is clear that these are not separate developments from a common goddess name, but separate uses of different word for dawn for a goddess. Surely the same can happen even when the nonmythological names have a common etymology, and sometimes it must happen in only some of the languages with shared etymology. In fact, the authors of this work are not foolish about this. Here is the first part of the entry for mouth: ``The mouth or utterance of a god--the two notions are often expressed with the same word [Sumerian ka, Akkadian pû]--is sometimes made into an independent deity in Mesopotamia. The etymological equivalent in Hebrew (peh) does not seem to have enjoyed a comparable divine status.''


4. Questionable gods.
      Basically editorial creativity, ``correcting'' the text in some way to discover god names. Some of this comes from altering lexical material absent in the original texts. (Word spacing was absent in the original Greek; vowels, indicated by pointing in the Masoretic text, were not indicated in the original Hebrew.) Some comes from changing similar-sounding or similar-appearing letters that might have been incorrectly transmitted. Example of the former reinterpretation: The Hebrew word ra, `evil,' may be reinterpreted as the name of the Egyptian sun god. Some of these questionable gods are imaginary in multiple ways.


5. Divinized human figures.
      Primarily Jesus, but taking a loose standard of ``god,'' also Mary, Enoch, Moses, and Elijah.

``Bible'' is understood by the editors in a fairly comprehensive way: as the Bible of the Orthodox Churches. This consists of the completest canon of the Septuagint (including all of what some traditions call the Apocrypha, even to 3 and 4 Maccabees), plus the Greek New Testament. The Masoretic text of the Hebrew Bible is used as a parallel source. ``Though many articles pay attention to the subsequent development of notions and concepts in the Pseudepigrapha, the latter have not been used as an independent quarry of theonyms.'' Authors also rely on rabbinic literature, but I assume they don't use Talmud as a source of theonyms either.

DDD

Direct Distance Dialing. I.e., direct long-distance dialing by customer. This initialism was used in the US and Canada; another Commonwealth usage was STD. Now that direct dialing is the default, of course, one is less likely to use these terms than one is to speak of buying a ``color TV'' or an ``electronic calculator.''

DDD

Digital-Digital-Digital. Audio CD's may be designated AAD, ADD, or DDD. The successive letters indicate whether analog or digital equipment was used in the respective stages of production: (1) original recording, (2) mixing and editing, (3) mastering (transcription).

DDD

Triple-Dee. One size larger than double-dee (DD).

DDDAS

Dynamic Data-Driven Applications System[s].

DDDDF

NASDAQ trading code for 4th Dimension Software Ltd. Numbers are not allowed in these codes (similarly, 7th Level has SEVL).

DDE

DichloroDiphenylEthane. A product of DDT breakdown; binds to testosterone receptors. Even today, this seems to be causing Florida Everglades toads to leave their girlfriends cold on Saturday night. It's getting harder and harder to be green.

The abbreviation is also used for a couple of dichlorodiphenyl dichloroethenes.

DDE

Direct Data Entry.

DDE

Drift-Diffusion Equations.

DDE

Dwight David Eisenhower. ``Ike.''

DDE

Dynamic Data Exchange. MS Windows term.

d/Deaf

Cover-your-ass-ese for deaf/hearing-impaired/whatever-the-latest-and-PCest-expression-is. (Some people insist on capitalizing the word to emphasize the separate-culture aspects of the situation or Whatever.)

DDES

Digital Data Exchange Specification.

DDG

Data Dependence Graph. Used in logic design.

DDHH, DD.HH.

Derechos Humanos. Spanish for `Human Rights.' (Initials doubled to represent plurals.)

ddI, DDI

DiDanosIn. Alternate name videx. An NRTI used in the treatment of AIDS.

DDI

Deputy Director of Intelligence.

DDK

Driver Development Kit (from Microsoft).

DDL

Data Definition Language.

DDL

Document Description Language.

DDN

Defense Data Network.

DDM

Distributed Data Management.

DDP

Datagram Delivery Protocol.

DD-PCR

Differential Display PCR.

DDR

Deutsche Demokratische Republik. German for GDR.

DDR

Dial-on-Demand Routing. A fancy kind of DDA: temporary WAN connections are opened in response to packets recognized as ``interesting.'' ``Interesting'' is predefined in terms of protocols and addresses.

DDR

Disarm, Demobilize, and Reintegrate. Initialism used by the Iraqi government and by the US-led coalition in Iraq. As tribal groups started flipping in 2007 and either fighting AQI or cooperating in the fight against AQI, the government side has tried to set up DDR programs, looking to the long term.

DDRO

Dual Dielectric Resonator Oscillator (DRO).

DDQ

2,3-Dichloro-5,6-DicyanobenzoQuinone.

DDS

DATAPHONE Digital Services.

DDS

Digital Data Service.

DDS

Digital Data Storage.

DDS

Direct Digital Service.

DDS

Direct Digital Synthesis.

DDS

Doctor of Dental Surgery.

DDSD

Delay Dial, Start Dial. Standard incantation to the Hayes modems, whose language became the official standard back in the early eighties.

DDSN

Distributed Decision Support Network. Sounds like your buddies helping you get rid of a hot potato. Cf. DDSS.

DDSS

Distributed Decision Support Server. Sounds like the sucker your buddies found for you to get rid of the hot potato. Cf. DDSN.

DDST

Double Daylight Saving Time. Clock time advanced by two hours relative to standard time. DDST makes the greatest sense at high latitudes, where Summer dusks are very late and where Winter dawns (which play a part in determining local standard times) are also late. DDST (under the name British Double Summer Time) was used in the UK during the Summers of WWII. (Otherwise, during the war, it was on single-hour DST.)

Newfoundland's independence was recognized by the UK in the Statute of Westminster (1932), but two years later it went broke and resumed the status of a colony until 1949. During WWII, Newfoundland followed Britain's lead in adopting DDST, but there was great resistance to DDST outside St. John's.

In 1988, the Canadian province of Newfoundland tried a DDST experiment in 1988. The shift occurred in Spring, substituting a two-hour ``spring forward'' for the usual one. That (let's call it ``simple shift'') might be the only instance in which DDST was implemented as a full two-hour shift. There were the usual drawbacks, and coordination problems with the rest of Canada were, oh, I'd say about twice as bad as with regular DST. (No, a factor of 2 doesn't make sense when you think about it. So don't think about it.) The response to DDST was positive, but DDST was dropped in subsequent years because there was not a majority for a single shift calendar. (Favoring the use of both DST and DDST, or of shifting to DDST on other than the dates that neighboring parts of Canada shift to DST, is support for DDST in principle, but these more complicated options are less preferable than ordinary DST for others who favor simple-shift DDST. Hence, there was not an effective majority for DDST. Similar issues arise in elections with three or more candidates.)

In July 1941, FDR proposed legislation that would have given him power to establish DST with time advances as large as two hours. We're getting off the subject of DDST now, but I'm sure you want to know that this and other DST bills languished until after the attack on Pearl Harbor. The following January, legislation was passed that established year-round one-hour DST for the duration [more precisely, until six months after the cessation of hostilities], and gave the president no discretion in the matter. At the end of the war, further legislation rescinded federally-mandated DST earlier than the date originally set, and War Time ended on Sunday, September 30.

DDT

An unbelievably effective insecticide. After it was first tested, all subsequently tested formulas were also found to be fabulously effective, until it was realized that the effect was due to DDT residue in the test chamber. DDT has been widely banned for its side-effects on beneficial insects and on other animals. Rachel Carson's Silent Spring was the Uncle Tom's Cabin that energized that movement. Although DDT has been outlawed in the US for years, we still see effects (see DDE).

In 2006, the WHO announced that it would encourage the use of DDT to fight malaria. The decision comes only decades too late for millions of dead.

The mnemonic to remember DDT's structure is

        A mosquito was heard to complain,
        That the chemists had poisoned his brain,
                The cause of his sorrow,
                Was para-dichloro-
        Di-phenyl Trichloroethane!

Developed by Paul H. Müller who received the 1948 Nobel Prize in Physiology or Medicine ``for his discovery of the high efficiency of DDT as a contact poison against several arthropods.'' (I'm not sure exactly when this work was done, but it was ca. 1936. You could look it up.)

DDX

Device-Dependent X-windows. As opposed to Device-Independent X (DIX), of course. Note that while the expression ``machine-dependent code'' referred to a coding style or (lack of) discipline, DDX refers to a part of X.

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