515 research outputs found
Effect of Diethylenetriamine and Triethylamine sensitization on the critical diameter of Nitromethane
In this work, the critical diameter for detonation was measured for Nitromethane (NM) sensitized with two different amines: Diethylenetriamine (DETA) and Triethylamine (TEA). The critical diameter in glass and polyvinylchloride tubes is found to decrease rapidly as the amount of sensitizer is increased, then increase past a critical amount of sensitizer. Thus the critical diameter reaches a minimum at a critical concentration of sensitizer. It was also found that the critical diameter is lower with DETA than with TEA
Optimal Pricing Effect on Equilibrium Behaviors of Delay-Sensitive Users in Cognitive Radio Networks
This paper studies price-based spectrum access control in cognitive radio
networks, which characterizes network operators' service provisions to
delay-sensitive secondary users (SUs) via pricing strategies. Based on the two
paradigms of shared-use and exclusive-use dynamic spectrum access (DSA), we
examine three network scenarios corresponding to three types of secondary
markets. In the first monopoly market with one operator using opportunistic
shared-use DSA, we study the operator's pricing effect on the equilibrium
behaviors of self-optimizing SUs in a queueing system. %This queue represents
the congestion of the multiple SUs sharing the operator's single \ON-\OFF
channel that models the primary users (PUs) traffic. We provide a queueing
delay analysis with the general distributions of the SU service time and PU
traffic using the renewal theory. In terms of SUs, we show that there exists a
unique Nash equilibrium in a non-cooperative game where SUs are players
employing individual optimal strategies. We also provide a sufficient condition
and iterative algorithms for equilibrium convergence. In terms of operators,
two pricing mechanisms are proposed with different goals: revenue maximization
and social welfare maximization. In the second monopoly market, an operator
exploiting exclusive-use DSA has many channels that will be allocated
separately to each entering SU. We also analyze the pricing effect on the
equilibrium behaviors of the SUs and the revenue-optimal and socially-optimal
pricing strategies of the operator in this market. In the third duopoly market,
we study a price competition between two operators employing shared-use and
exclusive-use DSA, respectively, as a two-stage Stackelberg game. Using a
backward induction method, we show that there exists a unique equilibrium for
this game and investigate the equilibrium convergence.Comment: 30 pages, one column, double spac
Interplay between spin-orbit coupling and van Hove singularity in the Hund's metallicity of SrRuO
We investigate the dynamical properties of SrRuO at zero and very low
temperature using density functional theory plus dynamical mean-field theory
with an exact diagonalization solver. By considering rotationally invariant
local interaction, we examine how Hund's coupling and spin-orbit coupling
affect the correlated nature of the system. In the absence of Hund's coupling,
the system shows a Fermi liquid behavior over the entire range of temperatures
we consider. We confirm that the Fermi liquid persists at zero temperature even
with nonzero Hund's coupling; however, at sufficient temperatures Hund's
coupling significantly reduces the Fermi liquid regime and the system evolves
into a typical Hund's metal. At the bare electronic occupancy of SrRuO
(), a stronger Hund's metallicity accompanies a larger long-time
correlator. Remarkably, electron doping further destabilizes the Fermi liquid
even though the long-time correlator and magnetic fluctuations decrease upon
doping. This suppression of the Fermi liquid is driven by the van Hove
singularity above the Fermi level in SrRuO, combined with an enhanced
Van Vleck susceptibility by spin-orbit coupling. Such findings point to the
important role that electronic structure plays in the behavior of Hund's
metals, in addition to magnetic fluctuations.Comment: 7 pages, 4 figure
Microscopic Theory of Rashba Interaction in Magnetic Metal
Theory of Rashba spin-orbit coupling in magnetic metals is worked out from
microscopic Hamiltonian describing d-orbitals. When structural inversion
symmetry is broken, electron hopping between -orbitals generates chiral
ordering of orbital angular momentum, which combines with atomic spin-orbit
coupling to result in the Rashba interaction. Rashba parameter characterizing
the interaction is band-specific, even reversing its sign from band to band.
Large enhancement of the Rashba parameter found in recent experiments is
attributed to the orbital mixing of 3d magnetic atoms with non-magnetic heavy
elements as we demonstrate by first-principles and tight-binding calculations.Comment: 5 pages, 2 figure
Lanczos exact diagonalization study of field-induced phase transition for Ising and Heisenberg antiferromagnets
Using an exact diagonalization treatment of Ising and Heisenberg model
Hamiltonians, we study field-induced phase transition for two-dimensional
antiferromagnets. For the system of Ising antiferromagnet the predicted
field-induced phase transition is of first order, while for the system of
Heisenberg antiferromagnet it is the second-order transition. We find from the
exact diagonalization calculations that the second-order phase transition
(metamagnetism) occurs through a spin-flop process as an intermediate step.Comment: 4 pages, 4 figure
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Cooperativity of Kv7.4 channels confers ultrafast electromechanical sensitivity and emergent properties in cochlear outer hair cells.
The mammalian cochlea relies on active electromotility of outer hair cells (OHCs) to resolve sound frequencies. OHCs use ionic channels and somatic electromotility to achieve the process. It is unclear, though, how the kinetics of voltage-gated ionic channels operate to overcome extrinsic viscous drag on OHCs at high frequency. Here, we report ultrafast electromechanical gating of clustered Kv7.4 in OHCs. Increases in kinetics and sensitivity resulting from cooperativity among clustered-Kv7.4 were revealed, using optogenetics strategies. Upon clustering, the half-activation voltage shifted negative, and the speed of activation increased relative to solitary channels. Clustering also rendered Kv7.4 channels mechanically sensitive, confirmed in consolidated Kv7.4 channels at the base of OHCs. Kv7.4 clusters provide OHCs with ultrafast electromechanical channel gating, varying in magnitude and speed along the cochlea axis. Ultrafast Kv7.4 gating provides OHCs with a feedback mechanism that enables the cochlea to overcome viscous drag and resolve sounds at auditory frequencies
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