16,894 research outputs found
Predicting the long time dynamic heterogeneity in a supercooled liquid on the basis of short time heterogeneities
We report that the local Debye-Waller factor in a simulated 2D glass-forming
mixture exhibits significant spatial heterogeneities and that these short time
fluctuations provide an excellent predictor of the spatial distribution of the
long time dynamic propensities [Phys.Rev.Lett. 93, 135701 (2004)]. In contrast,
the potential energy per particle of the inherent structure does not correlate
well with the spatially distributed dynamics
Coupled plasmon - phonon excitations in extrinsic monolayer graphene
The existence of an acoustic plasmon in extrinsic (doped or gated) monolayer
graphene was found recently in an {\it ab initio} calculation with the frozen
lattice [M. Pisarra {\it et al.}, arXiv:1306.6273, 2013]. By the {\em fully
dynamic} density-functional perturbation theory approach, we demonstrate a
strong coupling of the acoustic plasmonic mode to lattice vibrations. Thereby,
the acoustic plasmon in graphene does not exist as an isolated excitation, but
it is rather bound into a combined plasmon-phonon mode. We show that the
coupling provides a mechanism for the {\em bidirectional} energy exchange
between the electronic and the ionic subsystems with fundamentally, as well as
practically, important implications for the lattice cooling and heating by
electrons in graphene.Comment: 5 pages, 4 figure
Intermittency and Universality in Fully-Developed Inviscid and Weakly-Compressible Turbulent Flows
We performed high resolution numerical simulations of homogenous and
isotropic compressible turbulence, with an average 3D Mach number close to 0.3.
We study the statistical properties of intermittency for velocity, density and
entropy. For the velocity field, which is the primary quantity that can be
compared to the isotropic incompressible case, we find no statistical
differences in its behavior in the inertial range due either to the slight
compressibility or to the different dissipative mechanism. For the density
field, we find evidence of ``front-like'' structures, although no shocks are
produced by the simulation.Comment: Submitted to Phys. Rev. Let
Recovery of the Shape of the Mass Power Spectrum from the Lyman-alpha Forest
We propose a method for recovering the shape of the mass power spectrum on
large scales from the transmission fluctuations of the Lyman-alpha forest,
which takes into account directly redshift-space distortions. The procedure, in
discretized form, involves the inversion of a triangular matrix which projects
the mass power spectrum in 3-D real-space to the transmission power spectrum in
1-D redshift-space. We illustrate the method by performing a linear calculation
relating the two. A method that does not take into account redshift-space
anisotropy tends to underestimate the steepness of the mass power spectrum, in
the case of linear distortions. The issue of the effective bias-factor for the
linear distortion kernel is discussed.Comment: 18 pages, 4 figures; minor revision
Swelling and shrinking kinetics of a lamellar gel phase
We investigate the swelling and shrinking of L_beta lamellar gel phases
composed of surfactant and fatty alcohol after contact with aqueous
poly(ethylene-glycol) solutions. The height change is
diffusion-like with a swelling coefficient, S: . On
increasing polymer concentration we observe sequentially slower swelling,
absence of swelling, and finally shrinking of the lamellar phase. This behavior
is summarized in a non-equilibrium diagram and the composition dependence of S
quantitatively described by a generic model. We find a diffusion coefficient,
the only free parameter, consistent with previous measurements.Comment: 3 pages, 4 figures to appear in Applied Physics Letter
Emission and absorption noise in the fractional quantum Hall effect
We compute the high-frequency emission and absorption noise in a fractional
quantum Hall effect (FQHE) sample at arbitrary temperature. We model the edges
of the FQHE as chiral Luttinger liquids (LL) and we use the non-equilibrium
perturbative Keldysh formalism. We find that the non-symmetrized high frequency
noise contains important signatures of the electron-electron interactions that
can be used to test the Luttinger liquid physics, not only in FQHE edge states,
but possibly also in other one-dimensional systems such as carbon nanotubes. In
particular we find that the emission and absorption components of the excess
noise (defined as the difference between the noise at finite voltage and at
zero voltage) are different in an interacting system, as opposed to the
non-interacting case when they are identical. We study the resonance features
which appear in the noise at the Josephson frequency (proportional to the
applied voltage), and we also analyze the effect of the distance between the
measurement point and the backscattering site. Most of our analysis is
performed in the weak backscattering limit, but we also compute and discuss
briefly the high-frequency noise in the tunneling regime.Comment: 26 pages, 11 figure
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