signal

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sig·nal

(sig'năl),
1. Something that causes an action or conveys information.
2. A DNA template sequence that alters RNA polymerase transcription.
3. The end product observed when a specific sequence of DNA or RNA is deleted by some method.
4. The message transmitted on binding of an agonist to a receptor.

signal

(sĭg′nəl)
n.
Biology A physical entity, such as a chemical or an electromagnetic wave, that activates a cell receptor and elicits a specific response.
v. sig·naled, sig·naling, sig·nals or sig·nalled or sig·nalling
v.tr.
To cause an effect in (a cell) by the activation of a receptor, as by a neurotransmitter or hormone.

sig′nal·er, sig′nal·ler n.

signal

A measurable or recognisable indicator of an event or process.

signal

Medtalk A measurable or recognizable indicator of an event or process. See Magnetic resonance signal, Sexual body signal.

sig·nal

(sig'năl)
1. Something that causes an action.
2. A DNA template sequence that alters RNA polymerase transcription.
3. The end product observed when a specific sequence of DNA or RNA is deleted by some method.
4. Anything or action that communicates something.
References in periodicals archive ?
The new signalling system should see journey times improve by at least 10%, says George Clark, engineering manager for train systems at Tube Lines.
Answering a question, the official informed that 90 kilometres out of 433 kilometers Auto Block Signalling system and two stations out of 31 stations are opened for traffic after installation, testing and commissioning of modern computer based interlocking (CBI) system, he added.
Pakistan Railways is also working to replace its old signalling system with the latest computerized signalling system.
Bilour, attributed this colossal loss to human error, however, he hinted at out-dated signalling system that must be replaced with new one to ensure safe travel on trains.
ISLAMABAD, October 11, 2009 (Balochistan Times): A ray of hope has emerged for Pakistan Railways after a Saudi Bank has consented to finance the project to replace decades-old signalling system, which plays an important role in the smooth, safe, efficient train operation and above all, protects trains from accidents.