14,565 research outputs found
Transverse tunneling current through guanine traps in DNA
The current - voltage dependence of the transverse tunneling current through
the electron or hole traps in a DNA is investigated. The hopping of the charge
between the sites of the trap and the charge-phonon coupling results in a
staircase structure of the I-V curve. For typical parameters of the DNA
molecule the energy characteristics of a DNA trap can be extracted from the I-V
dependence, viz., for a small gate voltage the phonon frequency and for a large
gate voltage the hopping integral can be found from the positions of the steps
in the I-V curve. Formation of the polaronic state also results in the
redistribution of the tunneling current between the different sites of the
traps
Additional Evidence Supporting a Model of Shallow, High-Speed Supergranulation
Recently, Duvall and Hanasoge ({\it Solar Phys.} {\bf 287}, 71-83, 2013)
found that large distance separation travel-time differences from a
center to an annulus implied a model of the average
supergranular cell that has a peak upflow of at a depth of
and a corresponding peak outward horizontal flow of
at a depth of . In the present work, this effect
is further studied by measuring and modeling center-to-quadrant travel-time
differences , which roughly agree with this model.
Simulations are analyzed that show that such a model flow would lead to the
expected travel-time differences. As a check for possible systematic errors,
the center-to-annulus travel-time differences are found
not to vary with heliocentric angle. A consistency check finds an increase of
with the temporal frequency by a factor of two,
which is not predicted by the ray theory
Probabilistic Model Counting with Short XORs
The idea of counting the number of satisfying truth assignments (models) of a
formula by adding random parity constraints can be traced back to the seminal
work of Valiant and Vazirani, showing that NP is as easy as detecting unique
solutions. While theoretically sound, the random parity constraints in that
construction have the following drawback: each constraint, on average, involves
half of all variables. As a result, the branching factor associated with
searching for models that also satisfy the parity constraints quickly gets out
of hand. In this work we prove that one can work with much shorter parity
constraints and still get rigorous mathematical guarantees, especially when the
number of models is large so that many constraints need to be added. Our work
is based on the realization that the essential feature for random systems of
parity constraints to be useful in probabilistic model counting is that the
geometry of their set of solutions resembles an error-correcting code.Comment: To appear in SAT 1
Electron Correlations in Bilayer Graphene
The nature of electron correlations in bilayer graphene has been
investigated. An analytic expression for the radial distribution function is
derived for an ideal electron gas and the corresponding static structure factor
is evaluated. We also estimate the interaction energy of this system. In
particular, the functional form of the pair-correlation function was found to
be almost insensitive to the electron density in the experimentally accessible
range. The inter-layer bias potential also has a negligible effect on the
pair-correlation function. Our results offer valuable insights into the general
behavior of the correlated systems and serve as an essential starting-point for
investigation of the fully-interacting system.Comment: 4 pages, 3 figure
Magnetoelasticity theory of incompressible quantum Hall liquids
A simple and physically transparent magnetoelasticity theory is proposed to
describe linear dynamics of incompressible fractional quantum Hall states. The
theory manifestly satisfies the Kohn theorem and the -sum rule, and predicts
a gaped intra-Landau level collective mode with a roton minimum. In the limit
of vanishing bare mass the correct form of the static structure factor,
, is recovered. We establish a connection of the present approach
to the fermionic Chern-Simons theory, and discuss further extensions and
applications. We also make an interesting analogy of the present theory to the
theory of visco-elastic fluids.Comment: RevTeX 4, 6 pages; expanded version to appear in PRB; more technical
details, and discussions of the physics adde
A Fermi Fluid Description of the Half-Filled Landau Level
We present a many-body approach to calculate the ground state properties of a
system of electrons in a half-filled Landau level. Our starting point is a
simplified version of the recently proposed trial wave function where one
includes the antisymmetrization operator to the bosonic Laughlin state. Using
the classical plasma analogy, we calculate the pair-correlation function, the
static structure function and the ground state energy in the thermodynamic
limit. These results are in good agreement with the expected behavior at
.Comment: 4 pages, REVTEX, and 4 .ps file
Interpreting the bounds on Solar Dark Matter induced muons at Super-Kamiokande in the light of CDMS results
We consider the recent limits on dark matter - nucleon elastic scattering
cross section from the analysis of CDMS II collaboration using the two signal
events observed in CDMS experiment. With these limits we try to interpret the
Super-Kamiokande (SK) bounds on the detection rates of up-going muons induced
by the neutrinos that are produced in the sun from the decay of annihilation
products of dark matter (WIMPs) captured in the solar core. Calculated rates of
up-going muons for different annihilation channels at SK using CDMS bounds are
found to be orders below the predicted upper limits of such up-going muon rates
at SK. Thus there exists room for enhancement (boost) of the calculated rates
using CDMS limits for interpreting SK bounds. Such a feature is expected to
represent the PAMELA data with the current CDMS limits. We also show the
dependence of such a possible enhancement factor (boost) on WIMP mass for
different WIMP annihilation channels.Comment: 7 pages, 6 figure
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