337 research outputs found
Effect of disorder on a graphene p-n junction
We propose the theory of transport in a gate-tunable graphene p-n junction,
in which the gradient of the carrier density is controlled by the gate voltage.
Depending on this gradient and on the density of charged impurities, the
junction resistance is dominated by either diffusive or ballistic contribution.
We find the conditions for observing ballistic transport and show that in
existing devices they are satisfied only marginally. We also simulate
numerically the trajectories of charge carriers and illustrate challenges in
realizing more delicate ballistic effects, such as Veselago lensing.Comment: (v2)Version accepted to Phys. Rev.
Theoretical and Methodological Considerations in Aphasia Research and Practice - Response to Caramazza: Information Processing
TB
A Survey for Infall Motions toward Starless Cores. II. and Mapping Observations
We present the results of an extensive mapping survey of 53 `starless' cores
in the optically thick line of CS 2-1 and the optically thin lines of N2H+ 1-0
and C18O 1-0. The purpose of this survey was to search for signatures of
extended inward motions.
This study finds 10 `strong' and 9 `probable' infall candidates, based on
analysis and on the spectral shapes of CS lines.
From our analysis of the blue-skewed CS spectra and the
parameter, we find typical infall radii of 0.06-0.14 pc. Also, using a simple
two layer radiative transfer model to fit the profiles, we derive
one-dimensional infall speeds, half of whose values lie in the range of
0.05-0.09 km s. These values are similar to those found in L1544 by
Tafalla et al., and this result confirms that infall speeds in starless cores
are generally faster than expected from ambipolar diffusion in a strongly
sub-critical core. In addition, the observed infall regions are too extended to
be consistent with the `inside-out' collapse model applied to a very low-mass
star. In the largest cores, the spatial extent of the CS spectra with infall
asymmetry is larger than the extent of the core by a factor of
2-3. All these results suggest that extended inward motions are a common
feature in starless cores, and that they could represent a necessary stage in
the condensation of a star-forming dense core.Comment: Two tex files for manuscript and tables, and 38 figures. To appear in
ApJ
Effect of Shared and Unshared Listener Knowledge on Narratives of Normal and Aphasic Adults
TB
Heat to Electricity Conversion by a Graphene Stripe with Heavy Chiral Fermions
A conversion of thermal energy into electricity is considered in the
electrically polarized graphene stripes with zigzag edges where the heavy
chiral fermion (HCF) states are formed. The stripes are characterized by a high
electric conductance Ge and by a significant Seebeck coefficient S. The
electric current in the stripes is induced due to a non-equilibrium thermal
injection of "hot" electrons. This thermoelectric generation process might be
utilized for building of thermoelectric generators with an exceptionally high
figure of merit Z{\delta}T \simeq 100 >> 1 and with an appreciable electric
power densities \sim 1 MW/cm2.Comment: 8 pages, 3 figure
Abundances of Molecular Species in Barnard 68
Abundances for 5 molecules (C18O, CS, NH3, H2CO, and C3H2) and 1 molecular
ion (N2H+) and upper limits for the abundances of 1 molecule (13CO) and 1
molecular ion (HCO+) are derived for gas within the Bok globule Barnard 68
(B68). The abundances were determined using our own BIMA millimeter
interferometer data and single-dish data gathered from the literature, in
conjunction with a Monte Carlo radiative transfer model. Since B68 is the only
starless core to have its density structure strongly constrained via extinction
mapping, a major uncertainty has been removed from these determinations. All
abundances for B68 are lower than those derived for translucent and cold dense
clouds, but perhaps only significantly for N2H+, NH3, and C3H2. Depletion of CS
toward the extinction peak of B68 is hinted at by the large offset between the
extinction peak and the position of maximum CS line brightness. Abundances
derived here for C18O and N2H+ are consistent with other, recently determined
values at positions observed in common.Comment: 16 pages, 1 figure, accepted by AJ, typo corrected, reference removed
in Section 4.
Guidelines for OLAC Video Game Genre Terms (olacvggt)
A thesaurus of video game genre terms with a corresponding MARC authority record
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