DDT (redirected from dichlorodiphenyltrichloroethane)

DDT or 2,2-bis(p-chlorophenyl)-1,1,1,-trichloroethane, chlorinated hydrocarbon compound used as an insecticide. First introduced during the 1940s, it killed insects that spread disease and feed on crops. Swiss scientist Paul Müller was awarded the 1948 Nobel Prize in Physiology or Medicine for discovering (1939) DDT's insecticidal properties. DDT, however, is toxic to many animals, including humans, and it is not easily degraded into nonpoisonous substances and can remain in the environment and the food chain for prolonged periods. By the 1960s its harmful effects on the reproductive systems of fish and birds were apparent in the United States, where the insecticide had been heavily used for agricultural purposes. After the United States banned its use in 1972, the wildlife population returned, particularly the bald eagle and the osprey. Nevertheless, DDT use continues in parts of the world, particularly in tropical regions, to control the mosquitoes that spread malaria. In 2001 the Stockholm Convention on Persistent Organic Pollutants called for the phasing out of DDT once a cost-effective alternative becomes available.

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DDT

 in full dichlorodiphenyltrichloroethane

Synthetic insecticide belonging to the family of organic halogens. In 1939 its toxicity to a wide variety of insects was discovered (by Paul Hermann Müller, who was awarded a Nobel Prize for his work) and effectively used against many disease vectors. By the 1960s, many species of insects had developed populations resistant to DDT; meanwhile, this highly stable compound was accumulating along the food chain and having toxic effects on various birds and fishes. During the 1960s it and similar chemicals were found to have severely reduced the populations of certain birds, including the bald eagle.

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1.		DDT - Generic term for a program that assists in debugging other programs by showing individual machine instructions in a readable symbolic form and letting the user change them. In this sense the term DDT is now archaic, having been widely displaced by "debugger" or names of individual programs like "adb", "sdb", "dbx", or "gdb".
2.		DDT - Under MIT's fabled ITS operating system, DDT (running under the alias HACTRN) was also used as the shell or top level command language used to execute other programs.
3.		DDT - Any one of several specific debuggers supported on early DEC hardware. The DEC PDP-10 Reference Handbook (1969) contained a footnote on the first page of the documentation for DDT that illuminates the origin of the term: Historical footnote: DDT was developed at MIT for the PDP-1 computer in 1961. At that time DDT stood for "DEC Debugging Tape". Since then, the idea of an on-line debugging program has propagated throughout the computer industry. DDT programs are now available for all DEC computers. Since media other than tape are now frequently used, the more descriptive name "Dynamic Debugging Technique" has been adopted, retaining the DDT abbreviation. Confusion between DDT-10 and another well known pesticide, dichloro-diphenyl-trichloroethane (C14-H9-Cl5) should be minimal since each attacks a different, and apparently mutually exclusive, class of bugs. (The "tape" referred to was, incidentally, not magnetic but paper.) Sadly, this quotation was removed from later editions of the handbook after the suits took over and DEC became much more "businesslike". The history above is known to many old-time hackers. But there's more: Peter Samson, compiler of the original TMRC lexicon, reports that he named "DDT" after a similar tool on the TX-0 computer, the direct ancestor of the PDP-1 built at MIT's Lincoln Lab in 1957. The debugger on that ground-breaking machine (the first transistorised computer) rejoiced in the name FLIT (FLexowriter Interrogation Tape).