Linked Life Data

14765189

Source:http://linkedlifedata.com/resource/pubmed/id/14765189

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6974
pubmed:dateCreated
2004-2-6
pubmed:abstractText
Characterization of the microscopic fluctuations in systems that are far from equilibrium is crucial for understanding the macroscopic response. One approach is to use an 'effective temperature'--such a quantity has been invoked for chaotic fluids, spin glasses, glasses and colloids, as well as non-thermal systems such as flowing granular materials and foams. We therefore ask to what extent the concept of effective temperature is valid. Here we investigate this question experimentally in a simple system consisting of a sphere placed on a fine screen in an upward flow of gas; the sphere rolls because of the turbulence it generates in the gas stream. In contrast to many-particle systems, in which it is difficult to measure and predict fluctuations, our system has no particle-particle interactions and its dynamics can be captured fully by video imaging. Surprisingly, we find that the sphere behaves exactly like a harmonically bound brownian particle. The random driving force and frequency-dependent drag satisfy the fluctuation-dissipation relation, a cornerstone of statistical mechanics. The statistical mechanics of near-equilibrium systems is therefore unexpectedly useful for studying at least some classes of systems that are driven far from equilibrium.
pubmed:language
eng
pubmed:journal
pubmed:status
PubMed-not-MEDLINE
pubmed:month
Feb
pubmed:issn
1476-4687
pubmed:author
pubmed:issnType
Electronic
pubmed:day
5
pubmed:volume
427
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
521-3
pubmed:year
2004
pubmed:articleTitle
Statistical mechanics of a gas-fluidized particle.
pubmed:affiliation
Department of Physics and Astronomy, University of California, Los Angeles, California 90095-1547, USA.
pubmed:publicationType
Journal Article