The wave equations are important second order hyperbolic partial differential equations for the description of waves as they occur in most scientific and engineering disciplines such as sound waves, light waves, water waves, acoustics waves, electromagnetic waves, and fluid dynamics, optics, electromagnetism, solid mechanics, structural mechanics, quantum mechanics, etc.
One important second-order measure is the isophote curvature.
Two most important second-order statistical measures are the LCR and the AFD.
SB is most efficient and effective if the following assumptions are satisfied: (i) second-order polynomials are adequate approximations of the input/output functions implied by the simulation model; (ii) the signs of all first-order effects are known; and (iii) if two inputs have no important first-order effects, then they have no important second-order effects either (heredity property).
Nonetheless, these are important first-order estimates for understanding the development of irradiated rims on airless body materials.
An important first-order betweenness feature of AR-relations is the following: (R6) Disjunctivity: ([a,x,b]rightarrow ([a,x,c]vee [c,x,b])) (so for any (a,b,cin X,[aa,b]subseteq [a,c]cup [c,b])).
Elevation is also considered an important first-order classifier because it reflects aspects of lithology as well as recent island development, capturing both island building (including tectonics) and denudation.
This means that multi-degree-of-freedom models are important for an accurate representation of the actual system behaviour, although a single-degree-of-freedom model captures important first-order information about a lot of the non-linear phenomena in the low-frequency range.
Because many species of fungi, including P. obscurosporus, form mycorrhizal associations with trees, there is potential for intraspecific diversity to have important second-order effects on host plant productivity and growth.
The most important second-order interaction was climate × light (Table 4); the difference between the warm climate and the other two was relatively larger when seeds were subjected to light than to continuous darkness.
