156 research outputs found
A Database for TSSs of Human MicroRNAs
MicroRNAs (miRNAs) are small endogeneous non-coding RNAs of about 22nt length. These short RNAs regulate the expression of mRNAs by hybridizing with their 3'-UTRs or by translational repression. They have been shown to take crucial roles in many biological processes. Many of the current studies are focused over how mature miRNAs regulate mRNAs, even though there is very limited knowledge about their transcriptional loci. Primary miRNAs (pri-miRs) are first transcribed from the DNA, followed by the formation of precursor miRNA (pre-miR) by endonucleases activity, which finally produces mature miRNAs. Unfortunately, the identification of the loci of pri-miRs, and the associated information about transcription start sites (TSSs) and promoters is still in progress. This information, even though limited, may be useful for further study on the regulation of miRNAs. In this paper, we provide a novel database of miRNA TSSs (miRT) that might be a valuable resource for advanced research on miRNA regulation
Control of quantum thermodynamic behaviour of a charged magneto oscillator with momentum dissipation
In this work, we expose the role of environment, confinement and external
magnetic field () in determining the low temperature thermodynamic behaviour
in the context of cyclotron motion of a charged oscillator with anomalous
dissipative coupling involving the momentum instead of the much studied
coordinate coupling. Explicit expressions for different quantum thermodynamic
functions (QTF) are obtained at low temperatures for different quantum heat
bath characterized by spectral density function, . The power law
fall of different QTF are in conformity with third law of thermodynamics. But,
the sensitiveness of decay i.e. the power of the power law decay explicitly
depends on . We also separately discuss the influence of
confinement and magnetic field on the low temperature behavior of different
QTF. In this process we demonstrate how to control low temperature behaviour of
anomalous dissipative quantum systems by varying confining length , and
the temperature . Momentum dissipation reduces effective mass of the system
and we also discuss its effect on different QTF at low temperatures.Comment: 9 Pages, 3 Figures, Accepted in Phys. Rev.
Magnetic field symmetries of nonlinear transport with elastic and inelastic scattering
We study nonlinear electronic transport symmetries in Aharonov-Bohm
interferometers subjected to inelastic scattering effects and show that odd
(even) conductance terms are even (odd) in the magnetic field when the junction
is (left-right) spatially symmetric. This observation does not hold when an
asymmetry is introduced, as we show numerically, but odd conductance terms only
manifest a weak breakdown of the magnetic field symmetry. Under elastic
dephasing effects, the Onsager-Casimir symmetry is maintained beyond linear
response and under spatial asymmetries
Flux-dependent occupations and occupation difference in geometrically symmetric and energy degenerate double-dot Aharonov-Bohm interferometers
We study the steady-state characteristics and the transient behavior of the
nonequilibrium double-dot Aharonov-Bohm interferometer using analytical tools
and numerical simulations. Our simple setup includes noninteracting degenerate
quantum dots that are coupled to two biased metallic leads at the same
strength. A magnetic flux is piercing the setup perpendicularly. As we
tune the degenerate dots energies away from the symmetric point we observe four
nontrivial magnetic flux control effects: (i) flux dependency of the dots
occupation, (ii) magnetic flux induced occupation difference between the dots,
at degeneracy, (iii) the effect of "phase-localization" of the dots coherence
holds only at the symmetric point, while in general both real and imaginary
parts of the coherence are nonzero, and (iv) coherent evolution survives even
when the dephasing strength, introduced into our model using B\"uttiker probe,
is large and comparable to the dots energies and the bias voltage. Moreover,
not only finite dephasing strength does not destroy the coherence features, it
can provide new type of coherent oscillations. These four phenomena take place
when the dots energies are gated, to be positioned away from the symmetric
point, demonstrating that the combination of bias voltage, magnetic flux and
gating field, can provide delicate controllability over the occupation of each
of the quantum dots, and their coherence
The probe technique far-from-equilibrium: Magnetic field symmetries of nonlinear transport
The probe technique is a simple mean to incorporate elastic and inelastic
processes into quantum dynamics. Using numerical simulations, we demonstrate
that this tool can be employed beyond the analytically tractable linear
response regime, providing a stable solution for the probe parameters:
temperature and chemical potential. Adopting four probes: dephasing, voltage,
temperature, and voltage-temperature, mimicking different elastic and inelastic
effects, we focus on magnetic field and gate voltage symmetries of charge
current and heat current in Aharonov-Bohm interferometers, potentially
far-from-equilibrium. Considering electron current, we prove analytically that
in the linear response regime inelastic scattering processes do not break the
Onsager symmetry. Beyond linear response, even (odd) conductance terms obey an
odd (even) symmetry with the threading magnetic flux, as long as the system
acquires a spatial inversion symmetry. When spatial asymmetry is introduced
particle-hole symmetry assures that nonlinear conductance terms maintain
certain symmetries with respect to magnetic field and gate voltage. These
analytic results are supported by numerical simulations. Analogous results are
obtained for the electron heat current. We also demonstrate that a double-dot
Aharonov-Bohm interferometer acts as a rectifier when two conditions are met:
(i) many-body effects are included, here in the form of inelastic scattering,
and (ii) time reversal symmetry is broken
Quantum heat transfer in harmonic chains with self consistent reservoirs: Exact numerical simulations
We describe a numerical scheme for exactly simulating the heat current
behavior in a quantum harmonic chain with self-consistent reservoirs.
Numerically-exact results are compared to classical simulations and to the
quantum behavior under the linear response approximation. In the classical
limit or for small temperature biases our results coincide with previous
calculations. At large bias and for low temperatures the quantum dynamics of
the system fundamentally differs from the close-to-equilibrium behavior,
revealing in particular the effect of thermal rectification for asymmetric
chains. Since this effect is absent in the classical analog of our model, we
conclude that in the quantum model studied here thermal rectification is a
purely quantum phenomenon, rooted in the quantum statistics
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