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BACKGROUND: Sphingomyelin (SM) and cholesterol are 2 key lipid partners on cell membranes and on lipoproteins. Many studies have indicated the influence of cholesterol on SM metabolism. This study examined the influence of SM biosynthesis on cholesterol metabolism. METHODS: Inducible global Sms1 KO (knockout)/global Sms2 KO mice were prepared to evaluate the effect of whole-body SM biosynthesis deficiency on lipoprotein metabolism. Tissue cholesterol, SM, ceramide, and glucosylceramide levels were measured. Triglyceride production rate and LDL (low-density lipoprotein) catabolism were measured. Lipid rafts were isolated and LDL receptor mass and function were evaluated. Also, the effects of exogenous sphingolipids on hepatocytes were investigated. RESULTS: We found that total SMS (SM synthase) depletion significantly reduced plasma SM levels. Also, the total deficiency significantly induced plasma cholesterol, apoB (apolipoprotein B), and apoE (apolipoprotein E) levels. Importantly, total SMS deficiency, but not SMS2 deficiency, dramatically decreased LDL receptors in the liver and attenuated LDL uptake through the receptor. Further, we found that total SMS deficiency greatly reduced LDL receptors in the lipid rafts, which contained significantly lower SM and significantly higher glucosylceramide, as well as cholesterol. Furthermore, we treated primary hepatocytes and Huh7 cells (a human hepatoma cell line) with SM, ceramide, or glucosylceramide, and we found that only SM could upregulate LDL receptor levels in a dose-dependent fashion. CONCLUSIONS: Whole-body SM biosynthesis plays an important role in LDL cholesterol catabolism. The total SMS deficiency, but not SMS2 deficiency, reduces LDL uptake and causes LDL cholesterol accumulation in the circulation. Given the fact that serum SM level is a risk factor for cardiovascular diseases, inhibiting SMS2 but not SMS1 should be the desirable approach.

BackgroundSphingomyelin (SM) and cholesterol are two key lipid partners on cell membranes and on lipoproteins. Many studies have indicated the influence of cholesterol on SM metabolism. This study examined the influence of SM biosynthesis on cholesterol metabolism.MethodsInducible globalSms1KO/globalSms2KO mice were prepared to evaluate the effect of whole-body SM biosynthesis deficiency on lipoprotein metabolism. Tissue cholesterol, SM, ceramide, and glucosylceramide levels were measured. TG production rate and LDL catabolism were measured. Lipid rafts were isolated and LDL receptor mass and function were evaluated. Also, the effects of exogenous sphingolipids on hepatocytes were investigated.ResultsWe found that total SMS depletion significantly reduced plasma SM levels. Also, the total deficiency significantly induced plasma cholesterol, apoB, and apoE levels. Importantly, total SMS deficiency, but not SMS2 deficiency, dramatically decreased LDL receptors in the liver and attenuated LDL uptake through the receptor. Further, we found that total SMS deficiency greatly reduced LDL receptors in the lipid rafts which contained significantly lower SM and significantly higher glucosylceramide as well as cholesterol. Furthermore, we treated primary hepatocytes and Huh7 cells (a human hepatoma cell line) with SM, ceramide, or glucosylceramide, and we found that only SM could up-regulate LDL receptor levels in a dose-dependent fashion.ConclusionsWhole-body SM biosynthesis plays an important role in LDL-cholesterol catabolism. The total SMS deficiency, but not SMS2 deficiency, reduces LDL uptake and causes LDL-cholesterol accumulation in the circulation. Given the fact that serum SM level is a risk factor for cardiovascular diseases, inhibiting SMS2 but not SMS1 should be the desirable approach.Graphic Abstract

Aiming at the problem that there are many types of faults in the current track circuit and it is difficult to obtain high-quality fault label data, this paper proposes a fault diagnosis method for ZPW-2000R track circuit based on OC-SVM and DNN. In this method, OC-SVM is first used to classify and identify 48 monitoring data collected by ZPW-2000R track circuit to collect signal data of different fault types; then the DNN method is used to train the collected fault data to automatically classify the known fault data. A large number of experiments were carried out on this method using the data of ZPW-2000R track circuit, the diagnostic experimental results show that the proposed fault diagnosis method can effectively automatically collect the novel fault data and accurately detect the fault type, and the accuracy of fault diagnosis can reach more than 98%.

It is widely thought that small time steps lead to small numerical errors in the finite-difference time-domain (FDTD) simulations. In this paper, we investigated how time steps impact on numerical dispersion of two FDTD methods including the FDTD(2,2) method and the FDTD(2,4) method. Through rigorously analytical and numerical analysis, it is found that small time steps of the FDTD methods do not always have small numerical errors. Our findings reveal that these two FDTD methods present different behaviors with respect to time steps: (1) for the FDTD(2,2) method, smaller time steps limited by the Courant-Friedrichs-Lewy (CFL) condition increase numerical dispersion and lead to larger simulation errors; (2) for the FDTD(2,4) method, as time step increases, numerical dispersion errors first decrease and then increase. Our findings are also comprehensively validated from one- to three-dimensional cases through several numerical examples including wave propagation, resonant frequencies of cavities and a practical electromagnetic compatibility (EMC) problem.

Fluoroscopy is the imaging modality routinely used for cardiac device implantation. Due to the rising concern regarding the harmful effects of radiation exposure to both the patients and operation staffs, many efforts have been made to develop alternative techniques to achieve zero-fluoroscopy implantation. In this review, we describe the different methods aimed at avoiding the application of fluoroscopy in recent years, and evaluate their feasibility and safety in cardiac electronic device implantation.

Introduction: Ventricular arrhythmia is the most important risk factor for sudden cardiac death (SCD) after acute myocardial infarction (MI) worldwide. However, the molecular mechanisms underlying these arrhythmias are complex and not completely understood. Objective: Here, we evaluated whether caveolin-3 (Cav3), the structural protein of caveolae, plays an important role in the therapeutic strategy for ventricular arrhythmias. Methods: A model of cardiac-specific overexpression of Cav3 was established to evaluate the incidence of ventricular arrhythmias after MI in mice. Ca2+ imaging was employed to detect the propensity of adult murine cardiomyocytes to generate arrhythmias, and immunoprecipitation and immunofluorescence were used to determine the relationship of proteins. Additionally, qRT-PCR and western blotting were used to detect the mRNA and protein expression. Results: We found that cardiac-specific overexpression of Cav3 delivered by a recombinant adeno-associated viral vector reduced the incidence of ventricular arrhythmias and SCD after MI in mice. Ca2+ imaging and western blotting revealed that overexpression of Cav3 reduced diastolic spontaneous Ca2+ waves by inhibiting the hyperphosphorylation of ryanodine receptor-2 (RyR2) at Ser2814, rather than at Ser2808, compared to in rAAV-red fluorescent protein control mice. Furthermore, we demonstrated that Cav3-regulated RYR2 hyperphosphorylation relied on plakophilin-2 in hypoxia-stimulated cultured cardiomyocytes by western blotting, immunoprecipitation, and immunofluorescence in vitro. Conclusions: Our results suggested a novel role for Cav3 in the prevention of ventricular arrhythmias, thereby identifying a new target for preventing SCD after MI.

Hypertrophic cardiomyopathy is an inherited cardiovascular disease, and 70% of patients have left ventricular outflow tract obstruction. Ventricular septal myectomy has been the gold standard treatment for most patients with refractory symptoms. Due to higher mortality associated with medical facilities with less experience, alcohol septal ablation has been accepted as an alternative to conventional surgical myectomy. It offers lower all-cause in-hospital complications and mortality, which could be potentially more preferable for patients with serious comorbidities. In recent years, radiofrequency ablation, providing another option with reproducibility and a low risk of permanent atrioventricular block, has become an effective invasive treatment to relieve left ventricular outflow tract obstruction. Moreover, substantial progress has been made in gene therapy for hypertrophic cardiomyopathy. The principal objective of this review is to present recent advances in non-pharmaceutical interventions in hypertrophic cardiomyopathy.

In this paper, the study focus on the FDTD(2,2) and (2,4) methods based on the face-centered cubic (FCC). We analyze the influence of time step on the numerical dispersion of both methods has been analyzed, respectively. For the FCC-FDTD(2,2) method, numerical calculation result shows that the maximum time step defined by the Courant-Friedrichs-Levy (CFL) condition is the optimal time step to minimize the numerical dispersion in the constant spatial steps. On the contrary, with the time step approaches the CFL condition, the numerical dispersion in FCC-FDTD(2,4) method gradually decreases and then improves. The conclusion can be used to select the appropriate time step to improve the calculation accuracy of the FCC-FDTD method.

An iterative formulation of arbitrary-order FDTD method is proposed based on a face-centered cubic (FCC) in this paper. Through the distribution of electromagnetic field nodes in FCC grid, the coefficients of arbitrary-order iterative formulations are theoretically derived. We validate the proposed method by two numerical examples. The results of this studies can provide guidance for the practical application of high-order FCC-FDTD method.

The wake generated by the underwater structure can evolve into a wake vortex with a special flow structure, resulting in a change in the speed of sound distribution, which has an important impact on the propagation of parametric array in the ocean and causes fluctuations in the sound field. The difference-frequency sound wave generated by the parametric array is the core of the parametric array technology. The study of the difference-frequency sound field distribution characteristics is the basis for the development of the parametric array technology and the theory of the interaction of sound waves. The frequency domain algorithm is used to calculate and analyze the nonlinear acoustic scattering characteristics of the underwater vortex field and explore the nonlinear acoustic scattering characteristics of the wake field of a cylindrical structure under the conditions of different moments and Mach number. The results show that the spatial directivity of the nonlinear acoustic scattering field of the wake vortex will cause the directivity of the parametric acoustic field to shift. The difference-frequency wave becomes concave and convex on the opposite sides of the parabolic axis and the wave energy is focused and scattered. The focus will cause the amplitude of the wave to increase and decrease accordingly. The main lobe offset will increase as the flow velocity increases.

The echo of maneuvering targets are analyzed in this paper, which combined with Polynomial phase signals (PPSs), and compared the parameter estimation performance of PPSs based on the fractional Fourier transform(FRFT), the cubic phase function and the product cubic phase function(PCPF) for the echo characteristics. In the third section of the paper, sparse aperture imaging is performed on the aircraft, which flies smoothly and the echo is randomly missing, and the RD algorithm of the maneuvering target is compared with FRFT and PCPF algorithm.

In this letter, a three-dimensional finite-difference time-domain (FDTD) method that is second-order in time and fourth-order in space on a face-centered cubic (FCC) grid, termed as FCC-FDTD(2,4), is proposed to solve the time-domain Maxwell's equations. The proposed method shows a much lower numerical dispersion error compared with the errors of other FDTD schemes, such as the FCC-FDTD(2,2) method, the FDTD(2,2) method, and the FDTD(2,4) method. This improvement in the numerical dispersion results from the FCC grid and the fourth-order scheme in space used in the proposed FCC-FDTD(2,4) method. Then, the Courant–Friedrichs–Lewy condition is given through spectral analysis, and an analytical numerical dispersion relation is obtained and comprehensively studied through numerical results with the FCC-FDTD(2,2) method, the FDTD(2,2) method, and the FDTD(2,4) method. Compared with the other three FDTD methods, the proposed method has much smaller numerical dispersion errors. Finally, the accuracy of the proposed method is further validated with other numerical examples.

Sphingomyelin (SM) is one major phospholipids on lipoproteins. It is enriched on apolipoprotein B-containing particles, including very low-density lipoprotein (VLDL) and its catabolites, low-density lipoprotein (LDL). SM is synthesized by sphingomyelin synthase 1 and 2 (SMS1 and SMS2) which utilizes ceramide and phosphatidylcholine, as two substrates, to produce SM and diacylglyceride. SMS1 and SMS2 activities are co-expressed in all tested tissues, including the liver where VLDL is produced. Thus, neither Sms1 gene knockout (KO) nor Sms2 KO approach is sufficient to evaluate the effect of SMS on VLDL metabolism. We prepared liver-specific Sms1 KO/ global Sms2 KO mice to evaluate the effect of hepatocyte SM biosynthesis in lipoprotein metabolism. We found that hepatocyte total SMS depletion significantly reduces cellular sphingomyelin levels. Also, we found that the deficiency induces cellular glycosphingolipid levels which is specifically related with SMS1 but not SMS2 deficiency. To our surprise, hepatocyte total SMS deficiency has marginal effect on hepatocyte ceramide, diacylglyceride, and phosphatidylcholine levels. Importantly, total SMS deficiency decreases plasma triglyceride but not apoB levels and reduces larger VLDL concentration. The reduction of triglyceride levels also was observed when the animals were on a high fat diet. Our results show that hepatocyte total SMS blocking can reduce VLDL-triglyceride production and plasma triglyceride levels. This phenomenon could be related with a reduction of atherogenicity.

Diabetic nephropathy (DN) is the major cause of chronic kidney disease and end-stage renal disease. Previous studies have demonstrated that long-chain omega-3 polyunsaturated fatty acids (PUFAs) might have therapeutic potential in reducing proteinuria in DN. However, the local level of eicosanoids derived from PUFAs in the plasma of DN patients remains unclear. This work aims to study the eicosanoid profile difference in plasma of DN patients and type 2 diabetes (T2D) without DN. A total of 27 T2D patients with similar diabetic duration were recruited and divided into T2D+DN group and T2D+NDN (non-DN) group based on urinary albumin excretion (UAE) detection. Using LC-MS/MS-based metabolomics, DN patients showed increased level of lipoxygenase (LOX) metabolites (5-HETE and LTB4) and decreased levels of eicosanoids derived according to the cytochrome P450s (CYP450) metabolic pathway (5,6-DHET; 14,15-DHET and 9,10-diHOME). Receiver operating characteristics and logistic regression analysis revealed increased level LOX metabolites and decreased level of CYP450 metabolites were significantly correlated with the incidence of DN in T2D patients. LOX and CYP450 metabolites correlated with DN incidence in T2D patients, which might be treatment targets for DN in T2D patients.

The numerical dispersion is one of the main factors to affect the accuracy of the finite-difference time-domain (FDTD) method. It can be easy to be taken for granted that a smaller time step leads to smaller simulation errors. This paper reveals that smaller time steps do not always make more accurate results in FDTD simulations. We analytically investigated how time steps affect the numerical dispersion of two FDTD methods: the leapfrog FDTD(2,2) method and the FDTD(2,4) method. The investigations in this paper show that in the FDTD(2,2) method, a larger time step limited by the Courant-Friedrichs-Lewy (CFL) condition is more helpful to reduce the numerical dispersion error. However, in the FDTD(2,4) method, as the time step grows, the numerical dispersion error decreases at the beginning and then increases. Several numerical examples are carried out to verify our analysis.

OBJECTIVE This study aimed to comprehensively assess the characteristics and risk factors of hyperthyroidism with pulmonary hypertension (PH). METHODS This was a retrospective cross-sectional analysis of 315 consecutive patients with hyperthyroidism admitted to the endocrinology department of Tongji Hospital from February 2016 to December 2017. PH was defined as a pulmonary arterial systolic pressure above 35 mm Hg measured by echocardiography. RESULTS Among the 315 patients, 208 were females, the median age was 42 (30-51) years, and the median disease duration was 12 (3-48) months. Thirty-five percent (111/315) of patients were identified with PH. Patients with hyperthyroidism and PH showed significantly higher serum concentrations of free thyroxine (FT4), free triiodothyronine, thyroid receptor antibodies, total bilirubin (TB), direct and indirect bilirubin, lower serum levels of hemoglobin and creatinine, and more severe cardiac load (P < .05 for each) compared with patients without PH. Levels of serum FT4, free triiodothyronine, thyroid receptor antibodies, and thyroid peroxidase antibody were different among groups of patients with different levels of pulmonary arterial systolic pressure (P < .05 for each). Multivariate logistic regression analysis indicated that serum FT4 (odds ratio, 1.02; 95% CI, 1.01-1.04; P = .004) and TB (OR, 1.03; 95% CI, 1.00-1.06; P = .030) were independent risk factors for PH in patients with hyperthyroidism. CONCLUSION Elevated serum FT4 and TB levels may be independent risk factors for PH in patients with hyperthyroidism and valuable indicators for the identification and treatment of patients with PH and hyperthyroidism.

In this paper, a novel global optimization algorithm, named as Maxwell’s equations derived optimization (MEDO), is proposed. Using the Maxwell’s equations to analyse the behaviors of the time-varying current, the Ampere force is obtained from Fleming’s left hand rule. MEDO introduces an ‘Ampere force’ term, which is derived from Maxwell’s equations and is rigorous in physics, to drive the variables to the global optimal solution in the search space. In addition, introducing ‘gravity’ to MEDO can increase the stability of the optimizations. 11 classical benchmarks are tested, and results show that MEDO can always converge to numerical optimal solutions. To evaluate the proposed MEDO in solving the electromagnetic problems, four practical engineering applications are considered including the linear antenna array synthesis, frequency selected surface optimization, numerical dispersion reduction for finite-difference method, and parameters extraction of typical waveform. These examples are significant in electromagnetics, but tough to be solved because of their high dimensionality and strong nonlinearity. Numerical results show that MEDO can outperform several classic optimization methods, like wind driven optimization (WDO) and particle swarm optimization (PSO). Therefore, the electromagnetics-inspired MEDO is robust and of great potential in solving the electromagnetic optimization problems.

Background The results of human clinical trials investigating the effects of green tea on glycemic control are inconsistent. Methods We conducted a systematic review and meta-analysis of RCTs that examined the effects of green tea supplementation on glycemic control. A literature search in PubMed, Embase, and Cochrane Library databases for RCTs that investigated the effect of green tea consumption on glycemic control was performed up to February 2020. A random-effects model was used to estimate weighted mean difference (WMD) with 95% confidence intervals (CIs). Results Twenty-seven trials involving 2194 subjects were included in the meta-analysis. The pooled results showed that green tea significantly lowered fasting blood glucose by − 1.44 mg/dL (95%CI:-2.26, − 0.62 mg/dL; P I2 = 7.7%). However, green tea consumption did not significantly affect fasting insulin and HbA1c values. The mean differences were − 0.46μIU/mL (95% CI: − 1.10, 0.17μIU/mL; P = 0.21) for fasting insulin and − 0.06%; (95% CI: − 0.12, 0.01%; P = 0.07) for HbA1c concentrations. Heterogeneity was significant in fasting insulin (I2 = 46.8%) and mild in HbA1c (I2 = 1.7%). Conclusions In short-term trials, green tea supplementation significantly reduced fasting glucose, but had no significant effect on fasting insulin and HbA1c. Long-term trials assessing the effects of green tea supplementation on glycemic control are needed.

Pulmonary vein isolation (PVI) is the cornerstone of atrial fibrillation (AF) ablation. However, this procedure remains complex and time-consuming, and the recurrence of AF after PVI is still unsatisfactory. Current technologies have improved our knowledge of the association between radiofrequency lesion creation and ablation parameters (power and duration), which triggered the development of high-power short-duration (HPSD). During the past decade, several preclinical and clinical studies have been conducted to confirm the feasibility, safety, and outcome of PVI ablation with HPSD or very high-power short-duration (vHPSD) settings, which increased electrophysiologists' interests in the utility of HPSD strategies. This paper describes the theoretical basis and recent research findings of HPSD or vHPSD ablation and summarizes the state-of-the-art evidence behind the role of this strategy in PVI.

Background: Although evidence from animal and observational studies has supported the beneficial effects of green tea intake for lowering blood pressure (BP), randomized placebo-controlled trials (RCTs) have yielded conflicting results. In this meta-analysis of RCTs, we aimed to assess the effects of green tea supplementation on measures of BP control. Methods: The PubMed, Embase, and Cochrane Library databases were electronically searched from inception to August 2019 for all relevant studies. The results were pooled using the generic inverse-variance method with random-effects weighting and expressed as mean differences (MDs) with 95% confidence intervals (CIs). The quality of studies was assessed using the Jadad score. Publication bias was evaluated using funnel plots, Egger test, and Begg test. Results: Twenty-four trials with 1697 subjects were included in the meta-analysis. The pooled results showed that green tea significantly lowered systolic BP (SBP; MD: −1.17 mm Hg; 95%CI: −2.18 to −0.16mm Hg; P = .02) and diastolic BP (DBP; MD: −1.24 mm Hg; 95%CI:−2.07 to −0.40mm Hg; P = .004). Significant heterogeneity was found for both SBP (I2 = 43%) and DBP (I2 = 57%). In addition, no evidence of significant publication bias was found from funnel plots or Egger test (P = .674 and P = .270 for SBP and DBP, respectively). Conclusion: Overall, green tea significantly reduced SBP and DBP over the duration of the short-term trials. Larger and longer-term trials are needed to further investigate the effects of green tea supplementation on BP control and clinical events.

Background Three-dimensional electroanatomic mapping systems have demonstrated a significant reduction in radiation exposure during radiofrequency catheter ablation procedures. We aimed to investigate the safety, feasibility and efficacy of a completely zero-fluoroscopy approach for catheter ablation of supraventricular tachycardia using the Ensite NavX navigation system compared with a conventional fluoroscopy approach. Methods A multicenter prospective non-randomized registry study was performed in seven centers from January 2013 to February 2018. Consecutive patients referred for catheter ablation of supraventricular tachycardia were assigned either to a completely zero-fluoroscopic approach (ZF) or conventional fluoroscopy approach (CF) according to the operator’s preference. Patients with atrial tachycardia were excluded. Results Totally, 1020 patients were enrolled in ZF group; 2040 patients ablated by CF approach were selected for controls. There was no significant difference between the zero-fluoroscopy group and conventional fluoroscopy group as to procedure time (60.3 ± 20.3 vs. 59.7 ± 22.6 min, P = 0.90), immediate success rate of procedure (98.8% vs. 99.2%, P = 0.22), arrhythmia recurrence (0.4% vs. 0.5%, P = 0.85), total success rate of procedure (98.4% vs. 98.8%, P = 0.39) or complications (1.1% vs. 1.5%, P = 0.41). Compared with the conventional fluoroscopy approach, the zero-fluoroscopy approach provided similar outcomes without compromising the safety or efficacy of the procedure. Conclusion The completely zero-fluoroscopy approach demonstrated safety and efficacy comparable to a conventional fluoroscopy approach for catheter ablation of supraventricular tachycardia, and mitigated radiation exposure to both patients and operators. Trial registration clinicaltrials.gov Identifier: NCT03042078; first registered February 3, 2017; retrospectively registered.

In this paper, the Nonlinear Coda Wave Interferometry (NCWI) method is studied for an overall assessment of cracking levels in very heterogeneous materials. NCWI is an ultrasonic method that mixes the performance of coda wave interferometry, which takes advantage of the heterogeneity of the medium to detect small changes, and nonlinear acoustics that displays high sensitivity to cracks. First, a series of experimental results are summarized. They include laboratory measurements on crack concrete samples as well as on perforated aluminium plates prepared so as to mimic cracks growth, and on-site measurements on a reduced 1:3 scale concrete nuclear containment plant (EDF VeRCoRs mock-up) under loading conditions that replicates decennial inspection. All experimental results demonstrate that the NCWI observables are sensitive to crack length (even when closed by post-tensioning) and can thus be used to monitor crack status in very heterogeneous material. Even though the experiments show a clear relation between crack length and crack opening, until very recently it was not possible to quantitatively recover information about the cracks as no model exists that can predict the NCWI experimental results. To tackle this problem the Spectral Element Method (SEM) is used to perform parametric numerical sensitivity studies of the NCWI observable to crack status. The aim here is to find simple and robust laws that links the NCWI observables to quantitative information about cracks (here the total crack length or the viscoelastic properties of an equivalent damaged zone). In this paper specific attention is given to the confrontation between numerical and experimental data obtained in perforated aluminium plates. A linear law between a CWI observable and the crack length is validated. Finally, perspective of an imagery NCWI based method is discussed.

Background Fluoroscopy is the imaging modality routinely used for cardiac device implantation and electrophysiological procedures. Due to the rising concern regarding the harmful effects of radiation exposure to both the patients and operation staffs, novel 3D mapping systems have been developed and implemented in electrophysiological procedure for the navigation of catheters inside the heart chambers. Their applicability in cardiac device implantation has been rarely reported. Our aim is to evaluate the feasibility and safety of permanent pacemaker implantation without fluoroscopy. Methods and results From January 2012 to June 2016, six patients (50 ± 15 years, four of six were female, one of who was at the 25th week of gestation) who underwent permanent pacemaker implantation were included (zero-fluoroscopy group). Data from 20 consecutive cases of implantation performed under fluoroscopy guidance were chosen as a control group (fluoroscopy group). Total implantation procedure time for single-chamber pacemaker was 51.3 ± 13.1 minutes in the zero-fluoroscopy group and 42.6 ± 7.4 minutes in the fluoroscopy group (P = 0.155). The implantation procedural time for a dual-chamber pacemaker was 88.3 ± 19.6 minutes and 67.3 ± 7.6 minutes in the zero-fluoroscopy and fluoroscopy groups (P = 0.013), respectively. No complications were observed during the procedure and the follow-up in the two groups, and all pacemakers worked with satisfactory parameters. Conclusion Ensite NavX system can be used as a reliable and safe zero-fluoroscopy approach for the implantation of single- or dual-chamber permanent pacemakers in specific patients, such as pregnant women or in extreme situations when the x-ray machine is not available.

The finite-difference methods (FDMs) suffer from the notorious numerical dispersion problem, especially when large simulation time steps and wideband pulses are involved. In this Letter, an approach to obtain optimised numerical dispersion for FDMs based on the adaptive wind driven optimisation (AWDO) is proposed. Numerical dispersion errors are analysed and minimised through the AWDO, then the authors could obtain the updating coefficients for the FDMs. The 2D case is exemplified to demonstrate the procedures in detail. Serval numerical experiments are carried out to validate the accuracy of the proposed approach.

This paper reports a numerical study of the sensitivity and applicability of the Nonlinear Coda Wave Interferometry (NCWI) method in a heterogeneous material with a localized microcracked zone. We model the influence of a strong pump wave on the localized microcracked zone as a small average increase in the length of each crack. Further probing of this microcracked zone with a multiply scattered ultrasonic wave induces small changes to the coda-type signal, which are quantified with coda wave interferometry. A parametric sensitivity study of the CWI observables with respect to the changes in crack length is established via numerical simulations of the problem using a 2D spectral element method (SEM2D). The stretching of the signal, proportional to the relative variation in effective velocity, is found to be linearly proportional to the global change in crack length, while the other CWI parameter, the remnant decorrelation coefficient, is found to be quadratically proportional to the crack length change. The NCWI method is shown to be relevant for the detection of different damaged material states in complex solids. The reported numerical results are especially significant in the context of quantitative nondestructive evaluation of micro-damage level of a heterogeneous materials using nonlinear ultrasound signals.