Where does kink collide?

A kink is the sharp corner in the demand curve that a firm in an oligopoly believes it faces at the going price. Sweezy's 1939 Demand under conditions of oligopoly argued that rivals match a price cut but ignore a price rise, so the curve bends at the current price and marginal revenue jumps at that point, which keeps prices from moving; Hall and Hitch reached the same bent-curve picture independently in their 1939 Price theory and business behaviour. The referent is a corner in an economic schedule that links price to quantity demanded, and it is not a stable lump of energy in a field or a bend in a molecule.[1][2]

Unit

A single firm's perceived demand curve carrying one corner at the prevailing price

Recovery means

Not applicable

Measured by

Inferred from observed price rigidity and from estimated demand elasticities above and below the going price

A kink is a stable, particle-like lump of energy in a field that connects two neighbouring ground states of equal energy, so that the field is in one vacuum far to the left and the other far to the right. The travelling solitary-wave solutions of the sine-Gordon equation were computed by Perring and Skyrme in their 1962 A model unified field equation, and Rajaraman's 1982 textbook Solitons and instantons set out the kink as the standard example of a topological soliton, its stability protected by a conserved winding number. The referent is a localized field configuration measured by energy and topological charge, and it is neither a corner in a demand curve nor a bend in DNA.[3][4]

Unit

A single soliton solution carrying one unit of topological charge

Recovery means

Not applicable

Measured by

Characterised by its rest energy, spatial width, and the winding number that counts the vacua it separates

A kink is a sharp bend at a single point along the DNA double helix, where the chain turns abruptly instead of curving gently. Crick and Klug proposed in their 1975 Kinky helix that the helix can bend at a discrete site by disrupting the stacking of one base pair, which would let a long, stiff molecule fold tightly, for example where DNA wraps around the proteins that package it. The referent is a geometric defect in a molecule's backbone, described by a bend angle at one position, and it has nothing in common with a corner in a demand curve or a soliton in a field.[5]

Unit

A single sharp bend at one point along a DNA molecule, given as a bend angle in degrees

Recovery means

Not applicable

Measured by

Detected by X-ray crystallography, altered gel mobility, and cyclization assays, and reported as a bend angle