Entrainment (physics)

Entrainment (physics)

:"See entrainment for other types."Entrainment is the process whereby two interacting oscillating systems, which have different periods when they function independently, assume the same period. The two oscillators may fall into synchrony, but other phase relationships are also possible.

The system with the greater frequency slows down, and the other accelerates. Christian Huygens, a notable physicist, coined the term entrainment after he noticed, in 1666, that two pendulum clocks had moved into the same swinging rhythm, and subsequent experiments duplicated this process. Notably, the two pendula stabilized not in synchrony, but in antiphase. They satisfy the definition of entrainment because they have the same period, even though they have opposite phase. The accepted explanation for this is that small amounts of energy are transferred between the two systems when they are out of phase in such a way as to produce negative feedback. As they assume a more stable phase relationship, the amounts of energy gradually reduce to zero. In the realm of physics, entrainment appears to be related to resonance.

In the study of chronobiology entrainment occurs when rhythmic physiological or behavioral events match their period to an environmental oscillation (termed a zeitgeber, which is German for "timegiver"). The activity/rest (sleep) cycle is only one set of such events that is normally entrained by environmental cues whose period is ultimately determined by the earth's rotation. The term entrainment is justified because the biological rhythms are endogenous: they persist when the organism is isolated from periodic environmental cues. Circadian oscillations occur even in isolated organs, and it is believed that a master pacemaker in the mammalian brain, the SCN (suprachiasmatic nuclei), entrains the periphery. Such hierarchical relationships are not the only ones possible: two or more oscillators may couple in order to assume the same period without either being dominant over the other(s). This situation is analogous to Huygens' pendulum clocks.

When good sleep hygiene is insufficient, a person's lack of synchronization to night and day can have health consequences. There is significant variation within normal chronotypes' entrainment; it is normal for humans to awaken anywhere from about 5 a.m. to 9 a.m. However, patients with DSPS, ASPS and Non-24 hour sleep phase syndrome are improperly entrained to light/dark.

A similar phenomenon was characterized in hearing aids when the adaptive feedback cancellation is used. This chaotic artifact (entrainment) is observed when correlated input signals are presented to an adaptive feedback canceller.

See also

* brainwave synchronization.



ENTRAINMENT AVOIDANCE WITH POLE STABILIZATION [http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2008051569&WO=2008051569&DISPLAY=DESC]

Entrainment avoidance with a transform domain algorithm [http://www.freshpatents.com/Entrainment-avoidance-with-a-transform-domain-algorithm-dt20080424ptan20080095388.php]

ENTRAINMENT AVOIDANCE WITH AN AUTO REGRESSIVE FILTER [http://www.wipo.int/pctdb/en/wo.jsp?IA=WO2008051570&WO=2008051570&DISPLAY=STATUS]

Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Entrainment — may refer to:* Air entrainment, the intentional creation of tiny air bubbles in concrete * Brainwave entrainment, the practice of entraining one s brainwaves to a desired frequency * Entrainment (biomusicology), the synchronization of organisms… …   Wikipedia

  • Aspects of Physics — Infobox musical artist Name = Aspects of Physics Img capt = Img size = Landscape = Background = group or band Alias = Origin = San Diego, California, USA Genre = IDM, Minimalism Years active = 2000 ndash; present Label = Imputor? Rocket Racer… …   Wikipedia

  • Relaxation (physics) — In the physical sciences, relaxation usually means the return of a perturbed system into equilibrium. Each relaxation process can be characterized by a relaxation time τ. The simplest theoretical description of relaxation as function of time t is …   Wikipedia

  • Unison — For other uses, see Unison (disambiguation). Perfect unison  Play ( …   Wikipedia

  • List of mathematics articles (E) — NOTOC E E₇ E (mathematical constant) E function E₈ lattice E₈ manifold E∞ operad E7½ E8 investigation tool Earley parser Early stopping Earnshaw s theorem Earth mover s distance East Journal on Approximations Eastern Arabic numerals Easton s… …   Wikipedia

  • Luminiferous aether — The luminiferous aether: it was hypothesised that the Earth moves through a medium of aether that carries light In the late 19th century, luminiferous aether or ether, meaning light bearing aether, was the term used to describe a medium for the… …   Wikipedia

  • Aether drag hypothesis — In the 19th century, the theory of the luminiferous aether as the hypothetical medium for the propagation of light, was widely discussed. An important part of this discussion was the question concerning the state of motion of Earth with respect… …   Wikipedia

  • Free surface — In physics a free surface is the surface of a body that is subject to neither perpendicular normal stress nor parallel shear stress,cite web |url=http://www.vishay.com/company/brands/measurements group/guide/glossary/freesurf.htm |title=Glossary …   Wikipedia

  • Michelson–Morley experiment — Box plots based on data from the Michelson–Morley experiment The Michelson–Morley experiment was performed in 1887 by Albert Michelson and Edward Morley at what is now Case Western Reserve University in Cleveland, Ohio. Its results are generally… …   Wikipedia

  • Trance — denotes a variety of processes, techniques, modalities and states of mind, awareness and consciousness. Trance states may occur involuntarily and unbidden.The term trance may be associated with meditation, magic, flow, and prayer. It may also be… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”