36,911 research outputs found
Fabrication of Asymmetric Electrode Pairs with Nanometer Separation Made of Two Distinct Metals
We report a simple and reproducible method to fabricate two metallic
electrodes made of different metals with a nanometer-sized gap. These
electrodes are fabricated by defining a pair of gold electrodes
lithographically and electrodepositing a second metal onto one of them. The
method enables the fabrication of pairs of metallic electrodes that exhibit
distinct magnetic properties or work functions. The utility of this technique
is demonstrated by making single-electron tunneling devices incorporating 2-nm
gold nanocrystals.Comment: 3 figures, 1 colo
Relative Entropy: Free Energy Associated with Equilibrium Fluctuations and Nonequilibrium Deviations
Using a one-dimensional macromolecule in aqueous solution as an illustration,
we demonstrate that the relative entropy from information theory, , has a natural role in the energetics of equilibrium and
nonequilibrium conformational fluctuations of the single molecule. It is
identified as the free energy difference associated with a fluctuating density
in equilibrium, and is associated with the distribution deviate from the
equilibrium in nonequilibrium relaxation. This result can be generalized to any
other isothermal macromolecular systems using the mathematical theories of
large deviations and Markov processes, and at the same time provides the
well-known mathematical results with an interesting physical interpretations.Comment: 5 page
Generalized Haldane Equation and Fluctuation Theorem in the Steady State Cycle Kinetics of Single Enzymes
Enyzme kinetics are cyclic. We study a Markov renewal process model of
single-enzyme turnover in nonequilibrium steady-state (NESS) with sustained
concentrations for substrates and products. We show that the forward and
backward cycle times have idential non-exponential distributions:
\QQ_+(t)=\QQ_-(t). This equation generalizes the Haldane relation in
reversible enzyme kinetics. In terms of the probabilities for the forward
() and backward () cycles, is shown to be the
chemical driving force of the NESS, . More interestingly, the moment
generating function of the stochastic number of substrate cycle ,
follows the fluctuation theorem in the form of
Kurchan-Lebowitz-Spohn-type symmetry. When $\lambda$ = $\Delta\mu/k_BT$, we
obtain the Jarzynski-Hatano-Sasa-type equality:
1 for all , where is the fluctuating chemical work
done for sustaining the NESS. This theory suggests possible methods to
experimentally determine the nonequilibrium driving force {\it in situ} from
turnover data via single-molecule enzymology.Comment: 4 pages, 3 figure
Simulation of Parallel Blade-Vortex Interaction using a Discrete Vortex Method. G.U. Aero Report no. 9832
Numerical results are presented for two-dimensional vortex-aerofoil interaction using a grid-free
discrete vortex method. The effects of the passing vortex on the surface pressure distribution
and hence the aerodynamic force and moment of the aerofoil are examined in detail for a
variety of interaction geometries. For some head-on interaction cases, vortex-induced local
flow separation is also predicted on the aft part of the aerofoil surfaces. Extensive comparisons
are made with other numerical results and the results from the Glasgow University BVI windtunnel
test, which show good agreement
The 3-D Vortex Particle Method and the Fast Summation Algorithm. G.U. Aero Report 9620
In this report the vortex particle method developed by G.S. Winckelmans and
A. Leonard for the computation of 3-D unsteady viscous flows is briefly reviewed. Numerical
results are given for the interesting phenomenon of the fusion of two vortex rings, which shows that the method works well for long time computation. To reduce the high computational cost of the direct summation, a fast hierarchical algorithm for 3-D vortex particle interactions is being implemented
The 3-D Vortex Particle Method and the Fast Summation Algorithm. G.U. Aero Report 9620
In this report the vortex particle method developed by G.S. Winckelmans and
A. Leonard for the computation of 3-D unsteady viscous flows is briefly reviewed. Numerical
results are given for the interesting phenomenon of the fusion of two vortex rings, which shows that the method works well for long time computation. To reduce the high computational cost of the direct summation, a fast hierarchical algorithm for 3-D vortex particle interactions is being implemented
Properties of solutions of stochastic differential equations driven by the G-Brownian motion
In this paper, we study the differentiability of solutions of stochastic
differential equations driven by the -Brownian motion with respect to the
initial data and the parameter. In addition, the stability of solutions of
stochastic differential equations driven by the -Brownian motion is
obtained
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