595 research outputs found
Anticipated synchronization and the predict-prevent control method in the FitzHugh-Nagumo model system
We study the synchronization region of two unidirectionally coupled, in a
master-slave configuration, FitzHugh-Nagumo systems under the influence of
external forcing terms. We observe that anticipated synchronization is robust
to the different types of forcings. We then use the predict-prevent control
method to suppress unwanted pulses in the master system by using the
information of the slave output. We find that this method is more efficient
than the direct control method based on the master. Finally, we observe that a
perfect matching between the parameters of the master and the slave is not
necessary for the control to be efficient. Moreover, this parameter mismatch
can, in some cases, improve the control
Alkali Atoms Attached to He Nanodroplets
We have experimentally studied the electronic excitation of Na
atoms attached to He droplets by means of laser-induced fluorescence as
well as beam depletion spectroscopy. From the similarities of the spectra
(width/shift of absorption lines) with these of Na on He droplets, we
conclude that sodium atoms reside in a ``dimple'' on the droplet surface and
that superfluid-related effects are negligible. The experimental results are
supported by Density Functional calculations at zero temperature, which confirm
the surface location of Na, K and Rb atoms on He droplets. In the case of
Na, the calculated shift of the excitation spectra for the two isotopes is in
good agreement with the experimental data.Comment: 6 pages, 3 figures, sent to JLT
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