7,143 research outputs found
Strains and pseudo-magnetic fields in circular graphene rings
We demonstrate that circular graphene ring under a shear stress displays
strong pseudo-magnetic fields. We calculate the pseudo-magnetic field both from
continuum elasticity theory as well as molecular dynamics simulations. Stable
wrinkles are induced by shear deformations and lead to enhancement of the
pseudo-magnetic field. The strong pseudo-magnetic field found here can be
observed by imaging graphene flake at the atomic level e.g. through scanning
tunneling microscope.Comment: 11 pages, 8 figures. (Appendixes A and B are added) To appear in
Phys. Rev.
Analysis of Non-stationary Data for Heart-Rate Fluctuations in Terms of Drift and Diffusion Coefficients
We describe a method for analyzing the stochasticity in the non-stationary
data for the beat-to-beat fluctuations in the heart rates of healthy subjects,
as well as those with congestive heart failure. The method analyzes the returns
time series of the data as a Markov process, and computes the Markov time
scale, i.e., the time scale over which the data are a Markov process. We also
construct an effective stochastic continuum equation for the return series. We
show that the drift and diffusion coefficients, as well as the amplitude of the
returns time series for healthy subjects are distinct from those with CHF.
Thus, the method may potentially provide a diagnostic tool for distinguishing
healthy subjects from those with congestive heart failure, as it can
distinguish small differences between the data for the two classes of subjects
in terms of well-defined and physically-motivated quantities.Comment: 6 pages, two columns, 6 figure
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