Imaginary-time formulation of steady-state nonequilibrium: application to strongly correlated transport

We extend the imaginary-time formulation of the equilibrium quantum many-body theory to steady-state nonequilibrium with an application to strongly correlated transport. By introducing Matsubara voltage, we keep the finite chemical potential shifts in the Fermi-Dirac function, in agreement with the Keldysh formulation. The formulation is applied to strongly correlated transport in the Kondo regime using the quantum Monte Carlo method.Comment: 5 pages 3 figure

Shock-induced consolidation and spallation of Cu nanopowders

A useful synthesis technique, shock synthesis of bulk nanomaterials from nanopowders, is explored here with molecular dynamics simulations. We choose nanoporous Cu (∼11 nm in grain size and 6% porosity) as a representative system, and perform consolidation and spallation simulations. The spallation simulations characterize the consolidated nanopowders in terms of spall strength and damage mechanisms. The impactor is full density Cu, and the impact velocity (u_i) ranges from 0.2 to 2 km s^(−1). We present detailed analysis of consolidation and spallation processes, including atomic-level structure and wave propagation features. The critical values of u_i are identified for the onset plasticity at the contact points (0.2 km s^(−1)) and complete void collapse (0.5 km s^(−1)). Void collapse involves dislocations, lattice rotation, shearing/friction, heating, and microkinetic energy. Plasticity initiated at the contact points and its propagation play a key role in void collapse at low u_i, while the pronounced, grain-wise deformation may contribute as well at high u_i. The grain structure gives rise to nonplanar shock response at nanometer scales. Bulk nanomaterials from ultrafine nanopowders (∼10 nm) can be synthesized with shock waves. For spallation, grain boundary (GB) or GB triple junction damage prevails, while we also observe intragranular voids as a result of GB plasticity

State-Constrained Agile Missile Control with Adaptive-Critic-Based Neural Networks

In this study, we develop an adaptive-critic-based controller to steer an agile missile that has a constraint on the minimum flight Mach number from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. This class of bounded state space, free final time problems is very difficult to solve due to discontinuities in costates at the constraint boundaries. We use a two-neural-network structure called adaptive critic in this study to carry out the optimization process. This structure obtains an optimal controller through solving optimal control-related equations resulting from a Hamiltonian formulation. Detailed derivations of equations and conditions on the constraint boundary are provided. For numerical experiments, we consider vertical plane scenarios. Flight Mach number and the flightpath angle are the states and the aerodynamic angle of attack is treated as the control. Numerical results bring out some attractive features of the adaptive critic approach and show that this formulation works very well in guiding the missile to its final conditions for this state constrained optimization problem from an envelope of initial conditions

Adaptive Critic Based Neural Networks for Control-Constrained Agile Missile Control

We investigate the use of an `adaptive critic\u27 based controller to steer an agile missile with a constraint on the angle of attack from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. We use neural networks with a two-network structure called `adaptive critic\u27 to carry out the optimization process. This structure obtains an optimal controller through solving Hamiltonian equations. This approach needs no external training; each network along with the optimality equations generates the output for the other network. When the outputs are mutually consistent, the controller output is optimal. Though the networks are trained off-line, the resulting control is a feedback contro

Mapping of strongly correlated steady-state nonequilibrium to an effective equilibrium

By mapping steady-state nonequilibrium to an effective equilibrium, we formulate nonequilibrium problems within an equilibrium picture where we can apply existing equilibrium many-body techniques to steady-state electron transport problems. We study the analytic properties of many-body scattering states, reduce the boundary condition operator in a simple form and prove that this mapping is equivalent to the correct linear-response theory. In an example of infinite-U Anderson impurity model, we approximately solve for the scattering state creation operators, based on which we derive the bias operator Y to construct the nonequilibrium ensemble in the form of the Boltzmann factor exp(-beta(H-Y)). The resulting Hamiltonian is solved by the non-crossing approximation. We obtain the Kondo anomaly conductance at zero bias, inelastic transport via the charge excitation on the quantum dot and significant inelastic current background over a wide range of bias. Finally, we propose a self-consistent algorithm of mapping general steady-state nonequilibrium.Comment: 15 pages, 9 figure

Quantum State Discrimination with General Figures of Merit

We solve the problem of quantum state discrimination with "general (symmetric) figures of merit" for an even number of symmetric quantum bits with use of the no-signaling principle. It turns out that conditional probability has the same form for any figure of merit. Optimal measurement and corresponding conditional probability are the same for any monotonous figure of merit.Comment: 5 pages, 2 figure

W physics at the ILC with polarized beams as a probe of the Littlest Higgs Model

We study the possibility of using W pair production and leptonic decay of one of the W's at the ILC with polarized beams as a probe of the Littlest Higgs Model. We consider cross-sections, polarization fractions of the W's, leptonic decay energy and angular distributions, and left-right polarization asymmetry as probes of the model. With parameter values allowed by present experimental constraints detectable effects on these observables at typical ILC energies of 500 GeV and 800 GeV will be present. Beam polarization is further found to enhance the sensitivity.Comment: 17 pages, plain latex, 6 figures, replaced with version accepted by JHEP, typographical errors removed, notation and references improved, new references added, explanation added in appendix regarding beam polarization dependenc

Imaginary-time formulation of steady-state nonequilibrium in quantum dot models

We examine the recently proposed imaginary-time formulation for strongly correlated steady-state nonequilibrium for its range of validity and discuss significant improvements in the analytic continuation of the Matsubara voltage as well as the fermionic Matsubara frequency. The discretization error in the conventional Hirsch-Fye algorithm has been compensated in the Fourier transformation with reliable small frequency behavior of self-energy. Here we give detailed discussions for generalized spectral representation ansatz by including high order vertex corrections and its numerical analytic continuation procedures. The differential conductance calculations agree accurately with existing data from other nonequilibrium transport theories. It is verified that, at finite source-drain voltage, the Kondo resonance is destroyed at bias comparable to the Kondo temperature. Calculated coefficients in the scaling relation of the zero bias anomaly fall within the range of experimental estimates.Comment: 16 pages, 10 figures, Comparison to other theories adde

Metabolic syndrome does not affect sustained virologic response of direct-acting antivirals while hepatitis C clearance improves hemoglobin A1c.

AimTo determine whether successful treatment with directacting antivirals (DAA) is associated with improvements in hemoglobin A1c (HbA1c) and if type 2 diabetes mellitus (T2DM) or metabolic syndrome affects sustained virologic response (SVR).MethodsWe performed a retrospective analysis of all hepatitis C virus (HCV) patients at the VA Greater Los Angeles Healthcare System treated with varying DAA therapy between 2014-2016. Separate multivariable logistic regression was performed to determine predictors of HbA1c decrease ≥ 0.5 after DAA treatment and predictors of SVR 12-wk post treatment (SVR12).ResultsA total of 1068 patients were treated with DAA therapy between 2014-2016. The presence of T2DM or metabolic syndrome did not adversely affect SVR12. 106 patients had both HCV and T2DM. Within that cohort, patients who achieved SVR12 had lower mean HbA1c pre treatment (7.35 vs 8.60, P = 0.02), and lower mean HbA1c post-treatment compared to non-responders (6.55 vs 8.61, P = 0.01). The mean reduction in HbA1c after treatment was greater for those who achieved SVR12 than for non-responders (0.79 vs 0.01, P = 0.03). In adjusted models, patients that achieved SVR12 were more likely to have a HbA1c decrease of ≥ 0.5 than those that did not achieve SVR12 (adjusted OR = 7.24, 95%CI: 1.22-42.94).ConclusionIn HCV patients with T2DM, successful treatment with DAA was associated with a significant reduction in HbA1c suggesting that DAA may have a role in improving insulin sensitivity. Furthermore, the presence of T2DM or metabolic syndrome does not adversely affect SVR12 rates in patients treated with DAA

A risk assessment for the introduction of African swine fever into the Federated States of Micronesia

Subharat, S, Han, J, Cogger, N. "A risk assessment for the introduction of African swine fever into the Federated States of Micronesia" Apia, Samoa, "Food and Agriculture Organization of the United Nations", 19 pages, 10.4060/cc0421en. Licence: CC BY-NC-SA 3.0 IGO.falseApia, Samo