Where does homing collide?

In immunology, homing is the directed trafficking of lymphocytes out of the blood and into specific tissues or lymphoid organs, guided by adhesion molecules and chemokine signals that match a cell to its destination. Gowans and Knight's 1964 The route of re-circulation of lymphocytes in the rat showed that lymphocytes continuously recirculate and re-enter lymphoid tissue through specialised vessels, and Butcher and Picker's 1996 Lymphocyte homing and homeostasis set out the molecular address code that governs where each cell goes. The referent is a cell-level targeting process controlled by surface receptors, distinct from an animal navigating home or a weapon tracking a target.[1][2]

Unit

The selective rate at which circulating lymphocytes enter a given tissue

Recovery means

Not applicable

Measured by

Tracked by labelled-cell transfer, intravital imaging of vessel entry, and the expression of homing receptors and their tissue ligands

In animal behaviour, homing is the capacity of an animal to return to a familiar site, such as a nest or roost, from an unfamiliar release point, using cues that can include the sun, magnetic fields, and landmarks. Keeton's 1971 Magnets interfere with pigeon homing showed experimentally that homing pigeons rely in part on the Earth's magnetic field for orientation. The referent is whole-organism navigation back to a goal location, a different construct from a lymphocyte entering a tissue or a missile converging on a target.[3]

Unit

Accuracy and success of an animal's return to its home site from a distance

Recovery means

Not applicable

Measured by

Assessed by release-and-track experiments recording vanishing bearings, return rates, and return times under manipulated cues

In guidance and control engineering, homing is a guidance mode in which a vehicle senses the target's own emitted or reflected energy and continuously computes steering commands to close on it, as in a homing missile locked to a heat or radar return. Siouris's Missile guidance and control systems develops the seeker and control laws, such as proportional navigation, that drive the intercept. The referent is a feedback control scheme for a machine converging on a target, unrelated to a cell trafficking to tissue or an animal finding its way home beyond the shared image of seeking a destination.[4]

Unit

The closing geometry and miss distance between a guided vehicle and its target

Recovery means

Not applicable

Measured by

Evaluated by seeker tracking error, line-of-sight rate, and achieved miss distance at intercept