Where does gateway collide?

In economic and urban geography, a gateway city is a settlement sited at the entrance to a tributary region (a break-in-transport point or a natural pass) through which the trade of that hinterland must flow, giving it command over the region's long-distance commerce. Burghardt contrasted the gateway with the central place: where a central place sits at the centre of the area it serves, a gateway sits at its edge, astride the corridor that links the region to the wider world. The referent is a geographic node defined by its controlling position on a route into a hinterland.[1]

Unit

A city's command over the trade entering and leaving a tributary region

Recovery means

Not applicable

Measured by

Assessed by the share of a hinterland's trade funnelled through the city and its position on entry corridors

In computer networking, a gateway is a node that connects two otherwise incompatible networks, relaying and where necessary translating traffic so that hosts on each side can communicate. In Cerf and Kahn's internetworking design, gateways linked distinct packet networks and handled the forwarding and fragmentation needed to carry a datagram across a boundary; in everyday use the "default gateway" is the router a host sends its outbound traffic to. The referent is a bridging node defined by joining and translating between networks, not a city or a drug.[2]

Unit

The node that forwards and translates traffic between two networks

Recovery means

Not applicable

Measured by

Characterised by throughput and the forwarding or translation behaviour at the boundary between networks

In the study of adolescent drug use, a gateway drug is an early-used, widely available substance (classically alcohol, tobacco, or cannabis) whose use is statistically associated with later progression to harder drugs. Kandel's work described a developmental sequence of stages in involvement, with legal drugs tending to precede marijuana and marijuana tending to precede other illicit use; "gateway" labels that earlier rung. Whether the association is causal or instead reflects a shared underlying propensity remains debated; that caveat is ours to flag, not a settled claim. The referent is a position in a hypothesised progression of drug involvement, unrelated to a network node or a city.[3]

Unit

An early substance's place in a hypothesised sequence toward later drug use

Recovery means

Not applicable

Measured by

Studied through the longitudinal ordering of substance initiation and transition rates between stages