2,375 research outputs found
Quantum Corrections to Thermopower and Conductivity in Graphene
The quantum corrections to the conductivity and the thermopower in monolayer
graphene are studied. We use the recursive Green's function method to calculate
numerically the conductivity and the thermopower of graphene. We then analyze
these weak localization corrections by fitting with the analytical theory as
function of the impurity parameters and the gate potential. As a result of the
quantum corrections to the thermopower, we find large magnetothermopower which
is shown to provide a very sensitive measure of the size and strength of the
impurities. We compare these analytical and numerical results with existing
experimental measurements of magnetoconductance of single layer graphene and
find that the average size and strength of the impurities in these samples can
thereby be determined. We suggest favorable parameter ranges for future
measurements of the magnetothermopower
From non-symmetric particle systems to non-linear PDEs on fractals
We present new results and challenges in obtaining hydrodynamic limits for
non-symmetric (weakly asymmetric) particle systems (exclusion processes on
pre-fractal graphs) converging to a non-linear heat equation. We discuss a
joint density-current law of large numbers and a corresponding large deviations
principle.Comment: v2: 10 pages, 1 figure. To appear in the proceedings for the 2016
conference "Stochastic Partial Differential Equations & Related Fields" in
honor of Michael R\"ockner's 60th birthday, Bielefel
A NASTRAN trainer for dynamics
Presented here is an automated training tool that engineers can use to master the application of NASTRAN to dynamic problems. Example problems were selected to make classical solutions available for comparison. These comparisons can be used to evaluate the solution
An apodizing phase plate coronagraph for VLT/NACO
We describe a coronagraphic optic for use with CONICA at the VLT that
provides suppression of diffraction from 1.8 to 7 lambda/D at 4.05 microns, an
optimal wavelength for direct imaging of cool extrasolar planets. The optic is
designed to provide 10 magnitudes of contrast at 0.2 arcseconds, over a
D-shaped region in the image plane, without the need for any focal plane
occulting mask.Comment: 9 pages, 5 figures, to appear in Proc. SPIE Vol. 773
The TRENDS High-Contrast Imaging Survey. VII. Discovery of a Nearby Sirius-like White Dwarf System (HD 169889)
Monitoring the long-term radial velocity (RV) and acceleration of nearby
stars has proven an effective method for directly detecting binary and
substellar companions. Some fraction of nearby RV trend systems are expected to
be comprised of compact objects that likewise induce a systemic Doppler signal.
In this paper, we report the discovery of a white dwarf companion found to
orbit the nearby ( mas) G9 V star HD 169889.
High-contrast imaging observations using NIRC2 at Keck and LMIRCam at the LBT
uncover the (, ) companion
at an angular separation of 0.8'' (28 au). Thirteen years of precise Doppler
observations reveal a steep linear acceleration in RV time series and place a
dynamical constraint on the companion mass of . This "Sirius-like" system adds to the census of white dwarf
companions suspected to be missing in the solar neighborhood.Comment: Accepted to Ap
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