Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes

To help reveal the complete picture of linear kinetic drift modes, four independent numerical approaches, based on integral equation, Euler initial value simulation, Euler matrix eigenvalue solution and Lagrangian particle simulation, respectively, are used to solve the linear gyrokinetic electrostatic drift modes equation in Z-pinch with slab simplification and in tokamak with ballooning space coordinate. We identify that these approaches can yield the same solution with the difference smaller than 1\%, and the discrepancies mainly come from the numerical convergence, which is the first detailed benchmark of four independent numerical approaches for gyrokinetic linear drift modes. Using these approaches, we find that the entropy mode and interchange mode are on the same branch in Z-pinch, and the entropy mode can have both electron and ion branches. And, at strong gradient, more than one eigenstate of the ion temperature gradient mode (ITG) can be unstable and the most unstable one can be on non-ground eigenstates. The propagation of ITGs from ion to electron diamagnetic direction at strong gradient is also observed, which implies that the propagation direction is not a decisive criterion for the experimental diagnosis of turbulent mode at the edge plasmas.Comment: 12 pages, 10 figures, accept by Physics of Plasma

Dynamic disorder in receptor-ligand forced dissociation experiments

Recently experiments showed that some biological noncovalent bonds increase their lifetimes when they are stretched by an external force, and their lifetimes will decrease when the force increases further. Several specific quantitative models have been proposed to explain the intriguing transitions from the "catch-bond" to the "slip-bond". Different from the previous efforts, in this work we propose that the dynamic disorder of the force-dependent dissociation rate can account for the counterintuitive behaviors of the bonds. A Gaussian stochastic rate model is used to quantitatively describe the transitions observed recently in the single bond P-selctin glycoprotein ligand 1(PSGL-1)$-$P-selectin force rupture experiment [Marshall, {\it et al.}, (2003) Nature {\bf 423}, 190-193]. Our model agrees well to the experimental data. We conclude that the catch bonds could arise from the stronger positive correlation between the height of the intrinsic energy barrier and the distance from the bound state to the barrier; classical pathway scenario or {\it a priori} catch bond assumption is not essential.Comment: 4 pages, 2 figure

Comment on ``Manipulating the frequency entangled states by an acoutic-optical modulator''

A recent theoretical paper [1] proposes a scheme for entanglement swapping utilizing acousto-optic modulators without requiring a Bell-state measurement. In this comment, we show that the proposal is flawed and no entanglement swapping can occur without measurement.Comment: 6 pages, 2 figures submitted to Phys. Rev

RF-MEMS switch actuation pulse optimization using Taguchi's method

Copyright @ 2011 Springer-VerlagReliability and longevity comprise two of the most important concerns when designing micro-electro-mechanical-systems (MEMS) switches. Forcing the switch to perform close to its operating limits underlies a trade-off between response bandwidth and fatigue life due to the impact force of the cantilever touching its corresponding contact point. This paper presents for first time an actuation pulse optimization technique based on Taguchi’s optimization method to optimize the shape of the actuation pulse of an ohmic RF-MEMS switch in order to achieve better control and switching conditions. Simulation results show significant reduction in impact velocity (which results in less than 5 times impact force than nominal step pulse conditions) and settling time maintaining good switching speed for the pull down phase and almost elimination of the high bouncing phenomena during the release phase of the switch

Quantum Communication with Correlated Nonclassical States

Nonclassical correlations between the quadrature-phase amplitudes of two spatially separated optical beams are exploited to realize a two-channel quantum communication experiment with a high degree of immunity to interception. For this scheme, either channel alone can have an arbitrarily small signal-to-noise ratio (SNR) for transmission of a coherent ``message''. However, when the transmitted beams are combined properly upon authorized detection, the encoded message can in principle be recovered with the original SNR of the source. An experimental demonstration has achieved a 3.2 dB improvement in SNR over that possible with correlated classical sources. Extensions of the protocol to improve its security against eavesdropping are discussed.Comment: 8 pages and 4 figures (Figure 1; Figures 2a, 2b; Figure 2

Resistive damping implementation as a method to improve controllability in stiff ohmic RF-MEMS switches

This paper presents in detail the entire procedure of calculating the bias resistance of an ohmic RF-MEMS switch, controlled under resistive damping (charge drive technique). In case of a very stiff device, like the North Eastern University switch, the actuation control under resistive damping is the only way to achieve controllability. Due to the short switching time as well as the high actuation voltage, it is not practical to apply a tailored control pulse (voltage drive control technique). Implementing a bias resistor of 33 MΩ in series with the voltage source, the impact velocity of the cantilever has been reduced 80 % (13.2 from 65.9 cm/s), eliminating bouncing and high initial impact force during the pull-down phase. However, this results in an affordable cost of switching time increase from 2.38 to 4.34 μs. During the release phase the amplitude of bouncing has also been reduced 34 % (174 from 255 nm), providing significant improvement in both switching operation phases of the switch. © 2013 Springer-Verlag Berlin Heidelberg

Electronic tuning and uniform superconductivity in CeCoIn5

We report a globally reversible effect of electronic tuning on the magnetic phase diagram in CeCoIn_{5} driven by electron (Pt and Sn) and hole (Cd, Hg) doping. Consequently, we are able to extract the superconducting pair breaking component for hole and electron dopants with pressure and co-doping studies, respectively. We find that these nominally non-magnetic dopants have a remarkably weak pair breaking effect for a d-wave superconductor. The pair breaking is weaker for hole dopants, which induce magnetic moments, than for electron dopants. Furthermore, both Pt and Sn doping have a similar effect on superconductivity despite being on different dopant sites, arguing against the notion that superconductivity lives predominantly in the CeIn_{3} planes of these materials. In addition, we shed qualitative understanding on the doping dependence with density functional theory calculations.Comment: Accepted for publication in Phys. Rev. Lett. (October 1, 2012