18,407 research outputs found
Hot electrons in low-dimensional phonon systems
A simple bulk model of electron-phonon coupling in metals has been
surprisingly successful in explaining experiments on metal films that actually
involve surface- or other low-dimensional phonons. However, by an exact
application of this standard model to a semi-infinite substrate with a free
surface, making use of the actual vibrational modes of the substrate, we show
that such agreement is fortuitous, and that the model actually predicts a
low-temperature crossover from the familiar T^5 temperature dependence to a
stronger T^6 log T scaling. Comparison with existing experiments suggests a
widespread breakdown of the standard model of electron-phonon thermalization in
metals
The Dynamics of Sustained Reentry in a Loop Model with Discrete Gap Junction Resistance
Dynamics of reentry are studied in a one dimensional loop of model cardiac
cells with discrete intercellular gap junction resistance (). Each cell is
represented by a continuous cable with ionic current given by a modified
Beeler-Reuter formulation. For below a limiting value, propagation is found
to change from period-1 to quasi-periodic () at a critical loop length
() that decreases with . Quasi-periodic reentry exists from
to a minimum length () that is also shortening with .
The decrease of is not a simple scaling, but the bifurcation can
still be predicted from the slope of the restitution curve giving the duration
of the action potential as a function of the diastolic interval. However, the
shape of the restitution curve changes with .Comment: 6 pages, 7 figure
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