2,390 research outputs found
Detecting synchronization of self-sustained oscillators by external driving with varying frequency
We propose a method for detecting the presence of synchronization of
self-sustained oscillator by external driving with linearly varying frequency.
The method is based on a continuous wavelet transform of the signals of
self-sustained oscillator and external force and allows one to distinguish the
case of true synchronization from the case of spurious synchronization caused
by linear mixing of the signals. We apply the method to driven van der Pol
oscillator and to experimental data of human heart rate variability and
respiration.Comment: 9 pages, 7 figure
Coulomb drag between one-dimensional conductors
We have analyzed Coulomb drag between currents of interacting electrons in
two parallel one-dimensional conductors of finite length attached to
external reservoirs. For strong coupling, the relative fluctuations of electron
density in the conductors acquire energy gap . At energies larger than
, where
is the impurity scattering rate, and for , where is the
fluctuation velocity, the gap leads to an ``ideal'' drag with almost equal
currents in the conductors. At low energies the drag is suppressed by coherent
instanton tunneling, and the zero-temperature transconductance vanishes,
indicating the Fermi liquid behavior.Comment: 5 twocolumn pages in RevTex, added 1 eps-Figure and calculation of
trans-resistanc
The -closure of a solvable permutation group is solvable
Let be a positive integer and let be a finite set. The
-closure of is the largest permutation
group on having the same orbits as in its induced action on the
Cartesian product . The -closure and -closure of a solvable
permutation group need not be solvable. We prove that the -closure of a
solvable permutation group is always solvable for
Transport properties of single channel quantum wires with an impurity: Influence of finite length and temperature on average current and noise
The inhomogeneous Tomonaga Luttinger liquid model describing an interacting
quantum wire adiabatically coupled to non-interacting leads is analyzed in the
presence of a weak impurity within the wire. Due to strong electronic
correlations in the wire, the effects of impurity backscattering, finite bias,
finite temperature, and finite length lead to characteristic non-monotonic
parameter dependencies of the average current. We discuss oscillations of the
non-linear current voltage characteristics that arise due to reflections of
plasmon modes at the impurity and quasi Andreev reflections at the contacts,
and show how these oscillations are washed out by decoherence at finite
temperature. Furthermore, the finite frequency current noise is investigated in
detail. We find that the effective charge extracted in the shot noise regime in
the weak backscattering limit decisively depends on the noise frequency
relative to , where is the Fermi velocity, the
Tomonaga Luttinger interaction parameter, and the length of the wire. The
interplay of finite bias, finite temperature, and finite length yields rich
structure in the noise spectrum which crucially depends on the
electron-electron interaction. In particular, the excess noise, defined as the
change of the noise due to the applied voltage, can become negative and is
non-vanishing even for noise frequencies larger than the applied voltage, which
are signatures of correlation effects.Comment: 28 pages, 19 figures, published version with minor change
The VNTR polymorphism of the endothelial nitric oxide synthase gene and blood pressure in women at the end of pregnancy
Examine the association of the 4a/4b polymorphism of endothelial nitric oxide synthase (eNOS) with blood pressure in women at late pregnanc
Electron transport through a mesoscopic metal-CDW-metal junction
In this work we study the transport properties of a finite Peierls-Fr\"ohlich
dielectric with a charge density wave of the commensurate type. We show that at
low temperatures this problem can be mapped onto a problem of fractional charge
transport through a finite-length correlated dielectric, recently studied by
Ponomarenko and Nagaosa [Phys. Rev. Lett {\bf 81}, 2304 (1998)]. The
temperature dependence of conductance of the charge density wave junction is
presented for a wide range of temperatures.Comment: Latex, Revtex 3.0, 7 pages, 2 EPS figures (uses epfs
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