Where does cascade collide?

A sequential chain of activation steps in which each activated component switches on the next, so a small initial stimulus is amplified into a large and rapid response: in the blood clotting cascade a series of circulating enzymes activate one another in order until fibrin forms and seals a wound. Macfarlane's 1964 An enzyme cascade in the blood clotting mechanism, and its function as a biochemical amplifier set out this ordered enzyme sequence and argued that its stages act as a biochemical amplifier. The referent is a coupled chain of molecular reactions inside an organism, measured by clotting time and factor activity, and it is unrelated to agents copying a crowd, energy passing between eddies, or software filters arranged in stages.[1]

Unit

An ordered chain of enzyme activations that amplifies a signal

Recovery means

Inhibitors and feedback controls switch the chain off, and the activated factors are cleared so the system returns to rest

Measured by

Assessed by clotting assays, individual factor activity levels, and the timing of each activation step in the sequence

A situation in which people decide in sequence and each one, seeing the choices of those ahead, rationally sets aside their own private information and copies the crowd, so behaviour converges even when it rests on little real evidence. Bikhchandani, Hirshleifer, and Welch's 1992 A theory of fads, fashion, custom, and cultural change as informational cascades modelled how such cascades form, why they are fragile, and how they explain sudden shifts in mass behaviour. The referent is a chain of inference among decision makers in a market or society, tracked by the order and correlation of their choices, and it has nothing to do with clotting enzymes, turbulent eddies, or a pipeline of image classifiers.[2]

Unit

A sequence of imitative choices that discards private signals

Recovery means

A cascade can shatter the moment credible public information arrives, sending later choosers back to their own signals

Measured by

Studied by observing the order and correlation of choices, and reproduced in laboratory games where the private signals are known

The transfer of kinetic energy in a turbulent fluid from large eddies down through a range of progressively smaller eddies, until it reaches scales small enough for viscosity to dissipate it as heat. Kolmogorov's 1941 analysis, reprinted in 1991 as The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers, described the statistics of this inertial range and predicted how energy is distributed across scales. The referent is a flux of energy through the scales of a flowing fluid, quantified by spectra and dissipation rates, and it is a different thing entirely from an enzyme chain, a crowd copying itself, or classifiers arranged in stages.[3]

Unit

A flux of kinetic energy from large to small eddy scales

Recovery means

Not applicable

Measured by

Characterised by the energy spectrum, the inertial-range scaling exponent, and the rate of viscous dissipation at the smallest scales

A detection pipeline built as an ordered series of classifier stages, where each stage quickly rejects the easy negatives and passes only the surviving candidates to the next, more expensive stage, so most inputs are discarded early. Viola and Jones's 2001 Rapid object detection using a boosted cascade of simple features introduced this attentional cascade of boosted classifiers and used it to detect faces in real time. The referent is an engineered sequence of decision stages in software, tuned by detection and false-positive rates, and it shares only the word with a clotting chain, a herd of imitators, or the eddies of a turbulent flow.[4]

Unit

An ordered series of classifier stages that reject cases early

Recovery means

Not applicable

Measured by

Evaluated by the detection rate, the false-positive rate at each stage, and the average number of features computed per input