The Influence of Missing Data on Disabilities in Patients Treated with High-Dose Spinal Cord Stimulation: A Tipping Point Sensitivity Analysis

New waveforms have changed the field of Spinal Cord Stimulation (SCS) to optimize therapy outcomes, among which is High-Dose SCS (HD-SCS). Missing observations are often encountered when conducting clinical trials in this field. In this study, different approaches with varying assumptions were constructed to evaluate how conclusions may be influenced by these assumptions. The aim is to perform a tipping point sensitivity analysis to evaluate the influence of missing data on the overall conclusion regarding the effectiveness of HD-SCS on disability. Data from the Discover study were used, in which 185 patients with Failed Back Surgery Syndrome were included. Disability was evaluated before SCS and after 1, 3 and 12 months of HD-SCS. During the second, third and fourth visit, data from 130, 114 and 90 patients were available, respectively. HD-SCS resulted in a significant decrease in disability scores based on the analysis of observed data and with multiple imputations. The tipping point sensitivity analysis revealed that the shift parameter was 17. Thus, the conclusion concerning the time effect under a “missing at random” mechanism is robust when the shift parameter for the disability score is 17. From a clinical point of view, a shift of 17 points on disability is not very plausible. Therefore we tend to consider the conclusions drawn under “missing at random” as being robust.

COMPARATIVE STUDY OF EMPIRICAL CORRELATIONS AND EQUATIONS OF STATE EFFECTIVENESS FOR COMPRESSIBILITY FACTOR OF NATURAL GAS DETERMINATION

Introduction: Today, there are four main groups of methods for calculating the compressibility factor of natural gas: experimental measurements, equations of state, empirical correlations, modern methods based on genetic algorithms, neural networks, atomistic modeling (Monte Carlo method and molecular dynamics). A correctly chosen method can improve the accuracy of calculating gas reserves and predicting its production and processing. Aim: To find the optimal methods for calculating the z-factor following the characteristic thermobaric conditions. Methods: To determine the best method for calculating the compressibility factor, the effectiveness of using various empirical correlations and equations of state to predict the compressibility factor of hydrocarbon systems (reservoir gases and separation gases) of various compositions were evaluated by comparing numerical results with experimental data. Results and Discussion: Based on 824 experimental values of the compressibility factor for 235 various gas mixtures in the pressure range from 0.1 to 94 MPa and temperatures from 273 to 437 K, the optimal equation of state and empirical correlation dependence for accurate z-factor prediction was found. It is shown that for all gas mixtures the Peng-Robinson equation of state with the shift parameter and Brusilovsky equation of state allow achieving best results. For these methods, the average absolute relative error does not exceed 2%. Among the correlation dependences, the best results are shown by the Sanjari and Nemati Lay; Heidaryan, Moghadasi and Rahimi correlations with an error not exceeding 3%. Conclusions: It was found that for the proposed methods, the reduced pressure has a more significant effect on the accuracy of the calculated values than the reduced temperature. It is shown that when studying acid gas mixtures with a carbon dioxide content of more than 10%, the equations of state better describe the phase behavior of the system in comparison with empirical correlations.

A Broadband High-Efficiency Hybrid Continuous Inverse Power Amplifier Based on Extended Admittance Space

A novel hybrid continuous inverse power amplifier (PA) that is constituted by a continuum of PA modes from the continuous inverse class-F to the continuous inverse class-B/J is proposed, and a detailed mathematical analysis is presented. The fundamental and second harmonic admittance spaces of the hybrid PA proposed in this article are analyzed mathematically. By introducing the phase shift parameter into the current waveform formula of the hybrid continuous inverse PA, the design space of the fundamental and second harmonic admittance is expanded, further increasing the operating bandwidth. The efficiency of the amplifier under different parameter conditions is calculated. In order to verify this method, a broadband high-efficiency PA is designed and fabricated. The drain voltage and current waveforms of the amplifier are extracted for analysis. The experimental measured results show a 60.7–71.5% drain efficiency across the frequency band of 0.5–2.5 GHz (133% bandwidth), and the designed PA can obtain an 11.8–13.9 dB gain in the interesting frequency range. The measured results are confirmed to be in good agreement with theory and simulations.

Effect of Loading and Heating History on Deformation of LaCoO3

The aim of this work was to study cyclic stress–strain deformation behavior of LaCoO3 as a function of loading and heating history. The ferroelastic hysteretic deformation of LaCoO3 at different stresses and temperatures was characterized using effective Young’s modulus, hysteresis loop area and creep strain shift parameters. The deformation behavior of LaCoO3 was not significantly affected by the previous loading and heating history when tested at constant temperature. The high temperature strength and Young’s modulus of LaCoO3 were higher compared to at room temperature. A creep strain shift parameter was introduced to characterize creep strain in LaCoO3 for the first time.

Constraints on kinematic model from Pantheon SNIa, OHD and CMB shift parameter measurements

In this paper, we reconstruct the late-time cosmological dynamics using a purely kinematic approach. In particular, considering a divergence-free parametrization for deceleration parameter [Formula: see text], we first derive the jerk parameter [Formula: see text] and then confront it with combination of various cosmological datasets. We use the most recent observational datasets consisting of the 1048 Pantheon Supernovae Ia data points in the redshift range [Formula: see text], the 51 data points of observational Hubble parameter (OHD) measurements in the redshift range [Formula: see text], the Hubble constant [Formula: see text] (R19) and the CMB shift parameter measurements. We study the evolution of different cosmological quantities for the present model and compare it with the concordance [Formula: see text]CDM model. We find that only the combined Pantheon+OHD+R19 data shows good agreement with the [Formula: see text]CDM [Formula: see text] model within [Formula: see text] confidence region. We also find that our model successfully generates late time cosmic acceleration along with a decelerated expansion in the past.

Bounce cosmology in $$f({\mathcal {R}})$$ gravity

In this paper, we analyze the modified $$f({\mathcal {R}})$$ f ( R ) gravity models in Friedmann–Lemaître–Robertson–Walker (FLRW) background. The actions of bouncing cosmology are studied under consideration of different viable models in $$f({\mathcal {R}})$$ f ( R ) gravity theory that can resolve the difficulty of singularity in standard Big-Bang cosmology. Under different viable models in $$f({\mathcal {R}})$$ f ( R ) gravity theory, the cosmological constraints are plotted in provisions of cosmic-time, then investigated the bounce circumstance. In addition, the red-shift parameter is used to reconstruct the modified gravity, and compile the cosmological parameters that infer accelerated universe expansion. Finally, the situation stability is evaluated with a sound speed feature, which illustrates late-time stability.

Study of cosmological evolution via GGPDE f(R) models

This paper examines the cosmic evolution and current expansion for flat FRW universe through generalized ghost pilgrim dark energy model in [Formula: see text] gravity. For this purpose, we reconstruct the models in terms of red-shift parameter with respect to three scale factors, i.e. power-law, intermediate and a scale factor defining two unified phases. We study compatibility of reconstructed [Formula: see text] models through [Formula: see text]-[Formula: see text] planes whereas graphical analysis of squared speed of sound leads to investigate their stability. We also explore the behavior of cosmological parameters such as equation of state and deceleration parameters. Moreover, we study the existence of freezing/thawing regions via [Formula: see text]-[Formula: see text] planes. We conclude that squared speed of sound identifies both stability/instability of reconstructed [Formula: see text] models while equation of state and deceleration parameters specifies transition from decelerated to accelerated expanding cosmos. The [Formula: see text]-[Formula: see text] planes discover thawing as well as freezing regions for particular values of pilgrim parameter.

Confronting Einstein Yang Mills Higgs dark energy in light of observations

We study the observational aspects of Einstein Yang Mills Higgs dark energy model and constrain the parameters space from the latest observational data from type Ia supernovae, observational Hubble data, baryon acoustic oscillation data and cosmic microwave background radiation shift parameter data. It is found from the analysis of data that the Higgs field in presence of gauge fields can successfully describe the present accelerated expansion of the universe consistent with the astrophysical observations.