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Background Pulmonary vein isolation (PVI) is the most promising management method for paroxysmal atrial fibrillation (PAF). The P wave in the electrocardiogram (ECG) represents atrial depolarization. This study aims to correlate P‐wave parameters after PVI with outcomes. Methods This single‐center retrospective study included consecutive patients with first‐time PVI for PAF between 2018 and 2019 and targeted pulmonary veins (PVs). Procedure success was defined by freedom of ECG‐documented AF at 12 months. Digital 12 leads ECGs with 1–50 hertz bandpass filter were monitored before the procedure. P‐wave amplitude (PWA) and P‐wave terminal force in V1 (PTFV1) Corrected P‐wave duration (PWDc), and P‐wave dispersion (PWDisp), were measured before and after ablation. Results The final analysis included 180 patients, of which 130 (72%) had successful ablations and 53 (30%) had radiofrequency ablation (RF). Males comprised 71% of the patients; the mean age was 60. Demographics were similar between both arms p < 0.001. Patients with failed PVI had increased PWDc after PVI (139–146 ms, p < 0.001) compared to patients with successful PVI. PWA increased significantly after failed PVI (1.6–2 mV, p < 0.001) and successful PVI (1.6–1.8 mV, p = 0.008). PWD (hazard ratio [HR]: 2.5, 95% confidence interval [CI]: 1.4–4.2, p < 0.001) and PWA (HR: 1.7, 95% CI: 1.2–2.9, p = 0.03) were independently associated with PVI failure at 12 months. PWdisp and PTFV1 were not correlated with outcomes. Conclusion Increased PWDc and PWA after PVI were independently associated with failed ablation for PAF, supporting the role of P‐wave parameters in predicting outcomes.

BackgroundTo investigate the changes of P wave indices in atrial fibrillation (AF) patients after catheter ablation and the association between P wave indices and AF recurrence.MethodsPubMed, Embase, and Cochrane Database were searched through September 15th 2021 for studies on the association between P wave indices and AF with catheter ablation. Heterogeneity was estimated using the I2 statistic, the random effects model was used to calculate the pooled results, and summary receiver operating characteristic curve (SROC) was used to evaluate the predictive value.ResultsAmong included fourteen studies with 1674 AF patients, we found significantly decreased P wave dispersion (Pdis) (mean difference [MD]: − 6.5 ms, 95% confidence interval [95% CI]: − 11.81 to − 1.18, P = 0.02) after cryoballoon ablation (CBA) or radiofrequency ablation (RFA), and maximum P wave (Pmax) (MD: − 8.57 ms, 95% CI: − 17.03 to − 0.10, P = 0.05) after RFA only, but increased minimum P wave (Pmin) (MD: 3.43 ms, 95% CI: 1.07 to 5.79, P < 0.01) after CBA only. Pdis measured before ablation was remarkably higher (MD: 5.79 ms, 95% CI: 2.23 to 9.36, P < 0.01) in patients with recurrence than without; meanwhile, Pmax was higher measured both before and after ablation (MD: 6.49 ms, 95% CI: 2.30 to 10.69, P < 0.01 and MD: 11.2 ms, 95% CI: 2.88 to 19.52, P < 0.01). Furthermore, SROC analysis showed acceptable predictive efficiencies of Pdis (AUC = 0.776) and Pmax (AUC = 0.759) for AF recurrence.ConclusionPdis was significantly decreased after AF catheter ablation. Higher Pdis and Pmax may have predictive values for AF recurrence.

Compared with surface wave corresponding to the normal mode, which is widely studied, there is less research on guided-P wave corresponding to the leaking mode. Guided-P wave carries the dispersion information that can be used to construct the subsurface velocity structures. In this paper, to simultaneously estimate P-wave velocity (vP) and S-wave velocity (vS) structures, an integrated inversion method of guided-P and surface wave dispersion curves is proposed. Through the calculation of Jacobian matrix, the sensitivity of dispersion curves is quantitatively analyzed. It shows that the dispersion curves of guided-P and surface waves are, respectively, sensitive to the vP and vS. Synthetic model tests demonstrate the proposed integrated inversion method can estimate the vP and vS models accurately and effectively identify low-velocity interlayers. The integrated inversion method is also applied to the field seismic data acquired for oil and gas prospecting. The pseudo-2D vP, vS and Poisson’s ratio inversion results are of significance for near-surface geological interpretation. The comparison with the result of first-arrival traveltime tomography further demonstrates the accuracy and practicality of the proposed integrated inversion method. Not only in the field of exploration seismic, the guided-P wave dispersion information can also be extracted from the earthquake seismic, engineering seismic and ambient noise. The proposed inversion method can exploit previously neglected guided-P wave to characterize the subsurface vP structures, showing broad and promising application prospects. This compensates for the inherent defect that the surface wave dispersion curve is mainly sensitive to the vS structure.

Crustal thickness and composition are closely related to geology and tectonic evolution of the region. Studying the differences in the crustal thickness and composition of the South China Block (SCB) is important to gain a comprehensive understanding of multi-phase amalgamation, breakup, reworking, and regional geodynamic processes. In this study, teleseismic data from 135 high-density portable broadband stations from SinoProbe were processed using Common Conversion Point (CCP) stacking and H-κ stacking methods. The Moho depth and P-wave and S-wave velocity ratio ( V p / V s ) were studied. Our results revealed several insights about the tectonic processes in the SCB. First, the crustal structure and V p / V s ratios of the Cathaysia Block, Jiangnan Orogenic Belt, and Yangtze Block were significantly different. The average depth of the Moho in the Cathaysia Block was approximately 31 km, and the V p / V s ratios increased from the inland area (1.66) to the coastal area (1.78), indicating the oceanward increase of mafic proportion in the lower crust, which is related to the influence of the Paleo-Pacific Plate westward subduction. Second, the crustal thickness of Jiangnan Orogenic Belt deepens from east ca. 31 to the west ca. 42 km and the V p / V s ratios varied from 1.75 to 1.64, illustrating a relatively felsic crust, which could have been related to the Mesozoic upper crustal thickening under compression followed by the lower crust removal under the extensional background. Third, the average crustal thickness of the Yangtze Block was 42 km, and the V p / V s ratios ranged from 1.64 to 1.84, presenting a positive correlation between the Moho depth and the V p / V s ratio, which is explained by the relatively thick mafic lower crust. Based on the variations in the crustal structure and V p / V s ratios of the profile, we inferred that the central part of the Jiangnan Orogenic Belt was bounded by the Jiangshan-Shaoxing-Hengyang in the east and the Jiujiang-Shitai-Jishou in the west. The small-scale Moho depth undulations at the intersection of the Cathaysia Block and the Jiangnan Orogenic Belt could be related to the Mesozoic compression-extension geodynamic transformation.

The ratio of compressional‐ and shear‐wave velocities, Vp/Vs, in the continental crust is a useful proxy for silica abundance and partial melt. However, constraining crustal Vp/Vs remains challenging. Rayleigh wave site amplification is a valuable complement to phase velocity and can constrain crustal Vp. We develop a two‐step approach to jointly invert phase velocity and amplification for Vp/Vs in the crust and Vsv in the crust and uppermost mantle. We apply this joint inversion to construct new crustal Vp/Vs models for the western US from three different amplification data sets. The models contain Vp/Vs values in the range 1.6–1.85 and variations that are consistent between the three models and with previous results, including a westward increase of Vp/Vs across the Central Basin and Range. Crustal Vp/Vs across three regions of the Basin and Range are explored to gain insight into crustal composition and enhance understanding of crustal evolution.

To evaluate the deterioration degree of rock freeze–thaw damage in cold area engineering, it is necessary to establish an accurate freeze–thaw rock damage model and its uniaxial compression numerical simulation method. Therefore, indoor freeze–thaw cycle tests of saturated yellow sandstone were carried out. The porosity and P-wave velocity were measured, and uniaxial compression tests were conducted after different numbers of freeze–thaw cycles. The findings indicate that with an increasing number of freeze–thaw cycles, the elastic modulus, peak strength and wave velocity of the yellow sandstones gradually decrease, while the peak strain and the average porosity increase. The energy evolution law with different numbers of freeze–thaw cycles was analyzed, a freeze–thaw damage model was established according to the relative change in the dissipated energy ratio before and after freezing–thawing, and the accuracy of this damage model and five common damage models was evaluated by the uniaxial compressive strength and peak strain. The functional relationship between mesoscopic parameters and the number of freeze–thaw cycles was formulated to establish a numerical simulation method for saturated sandstones under uniaxial compression after freeze–thaw cycling. The reliability of the numerical method was verified by comparing the stress–strain curve, peak stress, peak strain and energy law with the experimental results.

The fluid-saturated porous layered (FSPL) media widely exist in the Earth’s subsurface and their overall mechanical properties, microscopic pore structure and wave propagation characteristics are highly relevant to the in-situ stress. However, the effect of in-situ stress on wave propagation in FSPL media cannot be well explained with the existing theories. To fill this gap, we propose the dynamic equations for FSPL media under the effect of in-situ stress based on the theories of poroacoustoelasticity and anisotropic elasticity. Biot loss mechanism is considered to account for the stress-dependent wave dispersion and attenuation induced by global wave-induced fluid flow. Thomsen’s elastic anisotropy parameters are used to represent the anisotropy of the skeleton. A plane-wave analysis is implemented on dynamic equations yields the analytic solutions for fast and slow P waves and two S waves. Modelling results show that the elastic anisotropy parameters significantly determine the stress dependence of wave velocities. Vertical tortuosity and permeability have remarkable effects on fast and slow P-wave velocity curves and the corresponding attenuation peaks but have little effect on S-wave velocity. The difference in velocities of two S waves occurs when the FSPL medium is subjected to horizontal uniaxial stress, and the S wave along the stress direction has a larger velocity, which implies that the additional anisotropy other than that induced by the beddings appears due to horizontal stress. Besides, the predicted velocity results have the reasonable agreement with laboratory measurements. Our equations and results are relevant to a better understanding of wave propagation in deep strata, which provide some new theoretical insights in the rock physics, hydrocarbon exploration and stress detection in deep-strata shale reservoirs.

We develop a global‐scale P wave velocity model (LLNL‐G3Dv3) designed to accurately predict seismic travel times at regional and teleseismic distances simultaneously. The model provides a new image of Earth's interior, but the underlying practical purpose of the model is to provide enhanced seismic event location capabilities. The LLNL‐G3Dv3 model is based on ∼2.8 millionP and Pnarrivals that are re‐processed using our global multiple‐event locator called Bayesloc. We construct LLNL‐G3Dv3 within a spherical tessellation based framework, allowing for explicit representation of undulating and discontinuous layers including the crust and transition zone layers. Using a multiscale inversion technique, regional trends as well as fine details are captured where the data allow. LLNL‐G3Dv3 exhibits large‐scale structures including cratons and superplumes as well numerous complex details in the upper mantle including within the transition zone. Particularly, the model reveals new details of a vast network of subducted slabs trapped within the transition beneath much of Eurasia, including beneath the Tibetan Plateau. We demonstrate the impact of Bayesloc multiple‐event location on the resulting tomographic images through comparison with images produced without the benefit of multiple‐event constraints (single‐event locations). We find that the multiple‐event locations allow for better reconciliation of the large set of direct P phases recorded at 0–97° distance and yield a smoother and more continuous image relative to the single‐event locations. Travel times predicted from a 3‐D model are also found to be strongly influenced by the initial locations of the input data, even when an iterative inversion/relocation technique is employed. Key Points A global P‐wave model (LLNL‐G3Dv3) is produced The LLNL‐G3Dv3 model is designed to enhance seismic event monitoring Accurate seismic location prior to tomographic inversion is essential

Coalbed methane (CBM) reservoirs usually require stimulation to enhance the permeability, thereby promoting CBM production. Realized by the conversion of the electromagnetic energy into heat, microwave heating may be an effective CBM stimulation method. In this study, the effects of microwave heating on the damage of coal were investigated through scanning electron microscope and ultrasonic wave tests. The results indicate that the mineral grain in coal generally disappears after microwave heating. For low-permeable coals with highly mineralized fractures, the dissolution of mineral could potentially enhance permeability and improve stress resilience. Microwave selective heating can lead to the opening and extension of original fractures and the generation of secondary fractures, reducing P-wave and S-wave velocity of coal. The stronger the anisotropy of coal is, the greater the microwave fracturing effect becomes. In a word, microwave heating has potential for assisting coalbed methane exploitation.

Though previous studies have shown that the presence of water strongly influences wave responses of rock fractures, water effects on wave behaviours across clay-rich rock fractures have been ambiguous until now. In the present study, we conducted considerable ultrasonic measurements on single rock fractures filled with kaolinite-dominant gouges at varying water saturation degrees to investigate the water effects on elastic S-wave propagation and attenuation across clay-rich rock fractures. The experimental results reveal that the S-wave velocity across single clay-rich rock fractures slightly increases and decreases with the progressively increasing water saturation degree. An increase in water saturation leads to a concave trend of the spectral amplitudes, while it moderately affects the central frequency of transmitted S-waves. In addition, the seismic quality factor across single clay-rich rock fractures follows an exponential growth trend with the water saturation, suggesting the exponentially negative relation between S-wave attenuation and the water saturation. We attribute the water saturation-dependent S-wave attributes across single clay-rich rock fractures to the combined effects of the local flow and the degradation of grain contacts. Compared to P-wave, S-wave exhibits less sensitivity to varying water saturation of clay-rich rock fracture. Upon increasing water saturation, S-waves display similar velocity and central frequency trends with P-waves. The tendencies of spectral amplitude and seismic quality factor for S-waves are approximately opposite to those for P-waves as the water saturation degree increases. We interpret these discrepancies by the fact that S-wave attributes across single water-saturated clay-rich rock fractures mainly depend on the properties of the skeletal frame, while the characteristics of the particles, pore fluid, and skeleton frame dominate P-wave behaviours. The outcomes of the current work facilitate our understanding of the fluid effects on the interaction of waves with clay-rich rock discontinuities.HighlightsS-wave velocity and peak spectral amplitude across single clay-rich rock fractures exhibit concave trends upon rising water saturation.The increased water saturation modestly affects the central frequency of S-wave propagating across single clay-rich rock fractures.The seismic quality factor for S-waves exponentially grows with the water saturation degree of clay-rich rock fractures.The higher the S-wave frequency, the higher the wave velocity, the less the wave energy transmission, and the more the wave dissipation.The water-induced evolution of peak spectral amplitude and seismic quality factor for S-waves is roughly opposite to that for P-waves.