Dust is a general name for minute solid particles with diameters less than 20 thou (500 micrometres). Particles in the atmosphere arise from various sources such as soil dust lifted up by wind, volcanic eruptions, and pollution. Dust in homes, offices, and other human environments contains human skin cells, small amounts of plant pollen, human and animal hairs, textile fibers, paper fibres, minerals from outdoor soil, and many other materials which may be found in the local environment.
A pattern, from the French patron, is a type of theme of recurring events or objects, sometimes referred to as elements of a set. These elements repeat in a predictable manner. It can be a template or model which can be used to generate things or parts of a thing, especially if the things that are created have enough in common for the underlying pattern to be inferred, in which case the things are said to exhibit the unique pattern. Pattern matching is the act of checking for the presence of the constituents of a pattern, whereas the detecting for underlying patterns is referred to as pattern recognition. The question of how a pattern emerges is accomplished through the work of the scientific field of pattern formation.
The most basic patterns are based on repetition and periodicity. A single template, or cell, is combined with duplicates without change or modification. For example, simple harmonic oscillators produce repeated patterns of movement.
Pattern recognition is more complex when templates are used to generate variants. For example, in English, sentences often follow the "N-VP" (noun - verb phrase) pattern, but some knowledge of the English language is required to detect the pattern. Computer science, ethology, and psychology are fields which study patterns.
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