(Science: clinical sign) appearance of the distal oesophagus, on a contrast oesophagram, in achalasia; also used to describe the proximal pyloric canal on upper gi series in congenital pyloric stenosis.
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... behaviour was controlled through the accumulation of 'simple' innate sign or cue triggers. For instance, Tinbergen found that gull chicks feed in response to the recognition of a red dot on their parents beak - they will even attempt to feed from a cardboard cutout as long as it ...
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