Background: Ivabradine is a heart rate-lowering drug that selectively inhibits the funny (I f ) current of the sinoatrial node. It is currently recommended in patients with heart failure (HF) with reduced ejection fraction (HFrEF) in sinus rhythm and a heart rate of ≥ 70 beats per minute (bpm) at rest. To investigate whether ivabradine has an effect on diastolic dysfunction, exercise tolerance and quality of life (QOL), we conducted a systemic review and meta-analysis of randomized controlled trials (RCTs). Methods: We searched PubMed, EMBASE and Cochrane CentralRegister of Clinical Trials for studies on the effect of ivabradine on left ventricular (LV) diastolic dysfunction, exercise tolerance, QOL, readmission for worsening HF and mortality in both patients with HF with preserved ejection fraction (HFpEF) and HFrEF.Results: Thirteen RCTs with 881 patients met the inclusion criteria. According to the pooled analysis, for the HFpEF subgroup, treatment with ivabradine resulted in a decrease in early diastolic mitral inflow to late diastolic flow ratio (E/A) (standardized mean difference (SMD): -0.53; 95% confidence interval (CI): -0.99, -0.07; P < 0.000) and increase in peak oxygen uptake during exercise (VO 2 ) (SMD: 0.05; 95% CI: -0.35, 0.45; P < 0.00; I 2 = 95.1%). Similar effect was seen in the HFrEF subgroup with decrease in E/A ratio (SMD: -0.33; 95% CI: -0.59, -0.06; P < 0.000) and early diastolic mitral inflow to annular velocity ratio (E/e') (SMD: -1.01; 95% CI: -1.49, -0.54; P < 0.012). Ivabradine therapy increased peak VO 2 and 6-min walk test (6MWT) in HFrEF patients (SMD: 0.83; 95% CI: 0.35, 1.32; P < 0.00; I 2 = 97.5% and SMD: 1.11; 95% CI: 0.82, 1.41; P < 0.000, respectively). There was also significant reduction in Minnesota Living with Heart Failure Questionnaire (MLHFQ) score (SMD: -0.68; 95% CI: -0.91, -0.45; P < 0.000). However, there was no significant difference in readmission for worsening HF and all-cause mortality between ivabradine and control (risk ratio (RR): 1.44; 95% CI: 0.73, 2.16; P < 0.148 and RR: 0.76; 95% CI: 0.19, 1.33; P < 0.907, respectively). Conclusions:Ivabradine therapy is associated with improved LV diastolic function, increases exercise tolerance and hence QOL, but it has no significant effect on readmission for worsening HF and allcause mortality.

To find a fast and reliable way predicting the energy deposition of helicon plasmas, this work focuses on machine learning algorithms. Data generation model and the distribution property of the source data are studied, then the classical algorithms and deep neural network (DNN) are built, and these algorithms are studied to test the performance on the energy deposition datasets. Both decision tree classifier (DTC) and support vector machine (SVM) find the electron temperature is the noise feature, and when it is included in the feature vector, the performance will degrade. Therefore feature selection needs be done to obtain high accuracy. For DNN, by directly changing the numbers of the hidden layers and units, test accuracy exceeds 0.95 when hidden layer is greater than three. The feature selection is automatically performed and the learning process is simpler in DNN. When the splitting ratio is varied, the generalization performance of DTC and SVM fluctuates, whereas DNN exhibits no evident change. Compared with the classical algorithms, DNN shows better stability when the source data are changed. The calculations suggest machine learning technique is a promising choice to predict the energy deposition of helicon plasmas.

A one-dimensional radial non-uniform fluid model is employed to study plasma behaviors with special emphasis laid on helicon discharges. The plasma density ne, electron temperature Te, electron azimuthal and radial drift velocities are investigated in terms of the plasma radius rp, magnetic field intensity B0 and gas pressure p0, by assuming radial ambipolar diffusion and negligible ion cyclotron movement. The results show that the magnetic confinement plays an important role in the discharge equilibrium, especially at low pressure, which significantly reduces Te compared with the case of a negligible magnetic field effect, and higher B0 leads to a greater average plasma density. Te shows little variations in the plasma density range of 10 11 cm −3-10 13 cm −3 for p0 < 3.0 mTorr. Comparison of the simulation results with experiments suggests that the model can make reasonable predictions of Te in low pressure helicon discharges.

The propagation properties of electromagnetic waves excited by helicon antenna with a parabolic radial electron density distribution in an external magnetic field were studied. Maxwell equations are numerically solved using the linear disturbance wave assumption to obtain energy distribution, when the magnetic intensity changes from 80 to 800 G. The radial electromagnetic wave and energy deposition intensity distributions were obtained. Results show that when magnetic intensity grows, the helicon wave is little damped and it can propagate into the bulk plasma; Trivelpiece-Gould (TG) wave is heavily damped at plasma-vacuum interface; the main energy absorption region moves towards the boundary gradually. When the magnetic intensity is lower than 100 G, the TG wave can propagate into the bulk plasma, and the plasma radial energy distribution is relatively uniform.

The pulsed inductive discharge ionizes the neutral gas and accelerates the plasma efficiently, and is accompanied by complicated phenomena during the discharge process. In order to study the transient flow field characteristics and the variations of the main flow parameters (e.g., velocity, density, pressure, etc.) with the magnetic induction intensity of the inductive pulsed plasma, the two-dimensional axisymmetric unsteady magnetohydrodynamic numerical model is introduced by employing the hyperbolic divergence cleaning method. The plasma is excited by the single pulse energy varying in the sine waveform with a period of 10 s, and the flow field of the peak magnetic induction intensity ranging from 0.1 T to 0.55 T, is calculated. The results show that the high density and speed region gradually moves forward and away from the coil, leaving the low density and speed plasma behind, meanwhile, the high temperature region is near the coil throughoutthe discharge, and the inductive magnetic field leads in the phase, compared with the flow parameters, which indicates the effective permeation of the pulsed energy into the neutral gas and the plasma. As the input single pulse energy increases, the maximum axial velocity of the plasma increases and the time at which the flow velocity reaches a peak value moves up. The current sheets of the same direction, which are located on the surface of the induction coil at the beginning, appear as the discharge initiates and moves forward with the influenced flow domain expanding as the process goes on, and an opposite sign current sheet grows when the time passes through the first quarter of the sine period, which is also near the surface of the coil and heats the low-density plasma and the neutral gas. The opposite direction current sheets slow down the velocity of the plasmoid. Due to the nonlinear property of the coil-plasma interaction, the acceleration efficiency of the induction coil improves irregularly as the magnetic induction intensity increases, which grows slowly at a low level, and when the intensity reaches a certain critical value, for the configuration studied in this work the particular value is 0.45 T, the acceleration efficiency increases significantly, indicating that a larger part of the pulsed energy is converted into the plasma kinetic energy.