Segment

Segment may mean:

Computing

Geometry

Science

See also

Segment (handwriting)

A segment of handwriting is a piece of the pen-tip trajectory between two defined segmentation points. If the occurrence of a minimum in the absolute (tangential) velocity is used as a heuristic for segmentation, the pen-tip trajectory can be subdivided into segments corresponding to ballistic strokes.

In handwriting recognition or optical character recognition, other terminologies may be used, such as the term glyph for a non-character (i.e.: sub character or multi-character) pattern.

Segmentation (biology)

Segmentation in biology refers to the division of some animal and plant body plans into a series of repetitive segments. This article focuses on the segmentation of animal body plans, specifically using the examples of the phyla Arthropoda, Chordata, and Annelida. These three phyla form segments by using a “growth zone” to direct and define the segments. While all three have a generally segmented body plan and use a “growth zone,” they use different mechanisms for generating this patterning. Even within these phyla, different organisms have different mechanisms for segmenting the body. Segmentation of the body plan is important for allowing free movement and development of certain body parts. It also allows for regeneration in specific individuals.

Definition

Segmentation is a difficult process to satisfactorily define. Many taxa (for instance the molluscs) have some form of serial repetition in their units, but are not conventionally thought of as segmented. Segmented animals are those considered to have organs that were repeated, or to have a body composed of self-similar units, but usually it is the parts of an organism that are referred to as being segmented.

Radiation

In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes:

Radiation is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Ionizing radiation carries more than 10 eV, which is enough to ionize atoms and molecules, and break chemical bonds. This is an important distinction due to the large difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation, consisting of helium nuclei, electrons or positrons, and photons, respectively. Other sources include X-rays from medical radiography examinations and muons, mesons, positrons, neutrons and other particles that constitute the secondary cosmic rays that are produced after primary cosmic rays interact with Earth's atmosphere.

Radiation (disambiguation)

Radiation is a process in which a body emits energy that propagates through a medium, or through empty space, to be absorbed by other bodies. Radiation may also refer to:

Physics

Ionizing radiation

Ionizing (or ionising in British English) radiation is radiation that carries enough energy to free electrons from atoms or molecules, thereby ionizing them. Ionizing radiation is made up of energetic subatomic particles, ions or atoms moving at high speeds (usually greater than 1% of the speed of light), and electromagnetic waves on the high-energy end of the electromagnetic spectrum.

Gamma rays, X-rays, and the higher ultraviolet part of the electromagnetic spectrum are ionizing, whereas the lower ultraviolet part of the electromagnetic spectrum, and also the lower part of the spectrum below UV, including visible light (including nearly all types of laser light), infrared, microwaves, and radio waves are all considered non-ionizing radiation. The boundary between ionizing and non-ionizing electromagnetic radiation that occurs in the ultraviolet is not sharply defined, since different molecules and atoms ionize at different energies. Conventional definition places the boundary at a photon energy between 10 eV and 33 eV in the ultraviolet (see definition boundary section below).