Mode of transport available, especially in underdeveloped or inaccessible regions. Although humans are able to walk without infrastructure, the transport can be enhanced through the use of roads, especially when using the human power with vehicles, such as bicycles and inline skates. Human-powered vehicles have also been developed for difficult environments, such as snow and water, by watercraft rowing and skiing; even the air can be entered with human-powered aircraft. Land transport covers all land-based transportation systems that provide for the movement of people, goods and services. Land transport plays a vital role in linking communities to each other. Land transport is a
Mode of a linear field Mode of a linear field In physics, a vector field is linear if it is a solution of a set of linear equations "E". For instance, in physics, the electromagnetic field in vacuum, defined in the usual (3 + 1)-dimensional space "S", obeys Maxwell's equations. A linear combination of electromagnetic fields, with constant, real coefficients, is a new field which obeys Maxwell's equations. The solutions of the linear equations are represented in a real vector space "M". A radius of "M", which represents proportional solutions, is called a "mode". A norm may be defined. For instance, in electromagnetism, it is