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Based on the extended Bogoliubov–de Gennes theory, the inhomogeneous stripe order and Majorana bound states are demonstrated in s -wave superconducting systems with Rashba spin–orbit interaction when the in-plane Zeeman field is applied. For a fully open square sample, topological phase transitions can be driven by the Zeeman field, and the stripe phase with spatially oscillating order parameter shows up across a critical field strength. The topological channels arise in this phase, which can be utilized to create and manipulate Majorana zero modes. Interestingly, (quasi-)one-dimensional channels with diminished pairing amplitude can be formed in narrow arms of a square loop, accompanied by the reconstruction of energy spectra of the condensate and the realization of robust Majorana zero-energy states at the ends of channels. The associated evolution of topological phases and the location of Majorana zero modes are highly sensitive to the field direction. Moreover, the effects of the rectangular aspect-ratio and the off-centered hole as well as the surface defects on Majorana end modes are explored in Rashba asymmetric loops. In comparison, the field-dependent evolution processes of low-energy levels behave more complicated because the emergence of confined topological channels can be effectively tuned by the length and width of loop arms as well as the size and position of an introduced small indentation at the outer edge. Rich patterns of Majorana corner-like states are generated for such asymmetric systems. Our theoretical predictions may shed new light on the tunability of Majorana zero modes and provide useful guidance for future experiments and applications. [ABSTRACT FROM AUTHOR]

We investigated the spectrum of density fluctuations of a liquid crystal, CB7CB, in two different orientations by using high-resolution inelastic x-ray scattering. Our analysis, based on Bayesian principles, revealed that high-frequency collective excitations propagate through this mesoscale-ordered sample in a peculiar manner that lies somewhere between those observed in liquids and crystalline systems. Interestingly, when we probed longer length scales, a more pronounced solid-like response emerged. This was mainly characterized by anomalously sharp inelastic excitations and the onset of shear mode propagation. Comparison with previous x-ray diffraction results suggests a correlation between the observed behavior and the mesogen arrangement. [ABSTRACT FROM AUTHOR]

Isotropic materials are required to adhere to various mechanical principles due to their limited thermal stability. For instance, it is essential for Poisson's ratio to be within the range of −1 to 0.5, and the longitudinal wave velocity must exceed the transverse wave velocity. Nevertheless, perfect crystals, as anisotropic materials, have the ability to defy conventional rules. Through the integration of high-throughput processes and first-principles calculations, a comprehensive exploration of known materials was conducted, resulting in the establishment of a database featuring an extreme anisotropic mechanism. This included the identification of abnormal Poisson's ratios (with the directional Poisson's ratio ranging from −3.00 to 3.67), the discovery of extreme negative linear compressibility, the determination of the upper and lower limits of the sound velocity, and other associated properties. Several materials with abnormal Poisson's ratios (<−1 or >0.5) were listed, and their peculiar mechanical behavior, wherein the volume decreased counterintuitively with uniaxial tension, was discussed. Finally, this study focused on the velocities of longitudinal and transverse waves, with specific emphasis on materials exhibiting transverse wave velocities that exceeded the longitudinal wave velocities. [ABSTRACT FROM AUTHOR]

This paper presents the design of a single-phase solid phononic crystal (PnC) structure featuring a regular hexagonal perforation pattern. The structure manifests three negative refraction bands, encompassing one for transverse waves and two for longitudinal waves, thereby enabling simultaneous control of shear and longitudinal waves. Due to the high symmetry of the triangular lattice, the equal frequency curves corresponding to the negative refraction band approach circular shapes, suggesting a nearly isotropic negative refraction effect. This negative refraction effect is achieved through specific mass resonance modes closely related to the porous structure designed in this paper. Initially, we analyze the band structure of the PnC, followed by designing the PnC plate structure to achieve negative refraction control for transverse waves at a frequency of 32.4 kHz, with a negative refraction index of −1. Additionally, negative refraction control for longitudinal waves is attained at frequencies of 44 and 64.54 kHz. Subsequently, we scrutinize the influence of various conditions on negative refraction, including different structural parameters, incident angles, and operating frequencies, while verifying the robustness of the designed phonon crystal structure. Leveraging the negative refraction characteristics of the structure, we construct an elastic wave lens to achieve perfect imaging of shear and longitudinal waves. Finally, employing finite element simulation and analyzing focusing imaging characteristics with different source positions, we validate that the results closely align with theoretical expectations. The solid PnC structure designed in this study holds significant potential for applications in the fields of elastic wave imaging. [ABSTRACT FROM AUTHOR]

Mode coupling and conversion between longitudinal and transverse modes are ubiquitous and universal in elastic waves, presenting a challenge in realistic applications such as nondestructive evaluation and geological exploration, where independent and separate manipulation of each mode is demanded. In this article, we propose a design of elastic metalens that can realize a high-efficiency focusing for the longitudinal wave and a V-shaped converging pattern for the transverse wave at the same time. The metalens is constructed from a metagrating, where each meta-atom has a simple configuration and renders high diffraction efficiency even for large steering angles, enabled by concurrent utilization of grating diffraction theory and advanced optimization algorithms. Interestingly, an arbitrary energy splitting ratio between the reflected longitudinal and transverse waves can be obtained by precisely controlling the coupling strength and conversion efficiency between them, providing improved flexibility and adaptability to various application environments. Two illustrative examples with a sharp focusing effect and tailored conversion efficiency are explicitly demonstrated, with a 50/50 energy splitting ratio between the longitudinal and transverse waves in the first case, and a 70/30 ratio in the second one. [ABSTRACT FROM AUTHOR]

This research aims to see how well back-propagation neural network (BPNN) approaches perform in estimating peak ground acceleration in the Himalayan region using various forms of input data (i.e., magnitude, focal depth, hypocentre and S-wave avg. velocity). These criteria were derived from the Himalayan Earthquake Catalogue, which includes all minor and significant earthquakes and their aftershock sequences in prior years. The analysis of high-quality seismological recorded data is important for earthquake prediction. The BPNN is employed for predicting the strong ground motion parameters such as peak ground acceleration, peak ground velocity and peak ground displacement using different activation functions at different layers. This research paper focuses on the model's training to analyze the dataset, including a few parameters to estimate the acceleration of the ground. Translated data into seismicity indicators, which are mathematically derived parameters. These seismicity indicators were utilized for the training of the BPNN to improve decision-making and for peak ground acceleration estimation. Artificial neural network models were used to predict the ground motion intensity measures for future events. The predictive parameters' contributions to the prediction of the considered intensity measurements are finally explored via sensitivity analysis. This study uses the multi-layer BPNN model to discover components in the Himalayan region, using the actual incidence of earthquake seismicity indicators as input and goal vectors. Finally, the BPNN model produces a good estimate for the peak ground acceleration of earthquakes. [ABSTRACT FROM AUTHOR]

Parotid glands are one of the most common sites for salivary gland tumors. Conventional imaging techniques have limited usefulness in the quantitative assessment of the parotid glands, making it difficult to differentiate between healthy tissue and tumors, as well as between benign and malignant tumors. Magnetic resonance elastography (MRE) is a non-invasive technique that may potentially overcome these limitations. Nevertheless, due to the size of the parotid gland, increased elastographic resolution is required. This may be achieved by applying shear waves at higher frequencies. However, it also results in stronger attenuation, making the illumination of the parotid challenging. Here, we describe a novel passive driver tailored to the anatomy of the human face, which minimizes the distance shear waves need to travel from the source to the area of interest and thus decreases shear wave attenuation, making high-frequency shear wave MRE feasible. [ABSTRACT FROM AUTHOR]

Seismic tomography observations show a low‐velocity feature in the upper mantle beneath eastern North America known as the Northern Appalachian Anomaly (NAA). Proposed models for the formation of the NAA include a remnant high‐temperature feature resulting from the passage of the Great Meteor Hotspot, edge‐driven convection, and ongoing asthenospheric upwelling. We investigate the structure of the lithosphere above the central portion of the NAA using data from the New England Seismic Transects (NEST) experiment. Ps receiver functions reveal two consistent interfaces beneath the dense northern line of NEST: the Moho (the base of the crust) and a deeper negative velocity gradient (NVG) feature located at depths between 60 and 110 km. We consider several potential explanations for this NVG feature; based on comparisons with previous results, we propose that it likely corresponds to the lithosphere‐asthenosphere boundary. Our results indicate that the lithosphere beneath New England is nonuniform and has likely been thinned. Plain Language Summary: Eastern North America has a rich geologic history. One puzzling aspect of the seismic structure of New England is that it overlies a prominent region of anomalously low seismic velocities in the upper mantle, known as the Northern Appalachian Anomaly (NAA). The origin of this feature remains poorly understood; furthermore, it is not clear whether and how the upper mantle anomaly has affected the tectonic plate above it. Here we use data from seismic stations of the New England Seismic Transects (NEST) array to study the thickness of the continental lithosphere above the NAA. Specifically, we examine P waves from distant earthquakes and look for evidence of P wave to S wave conversions at the base of the lithosphere. We find evidence for particularly thin lithosphere, indicating that it has been thinned over geologic time. Key Points: We use P‐to‐S receiver function analysis to identify negative velocity gradients beneath New EnglandWe find evidence for prominent negative velocity gradients between ∼60 and 110 km depth across stations of the NEST arrayWe infer relatively thin continental lithosphere above the Northern Appalachian Anomaly (NAA) in the upper mantle [ABSTRACT FROM AUTHOR]

AbstractThe present work is implicated with the investigation of wave propagation in a homogeneous, isotropic, non-local microelongated viscothermoelastic solid half space with variable thermal conductivity under the dual phase lag (DPL) model. It is found analytically that three coupled longitudinal waves and one independent transverse wave exist in the medium which travel with distinct speeds. Reflection coefficients and energy ratios of various reflected waves are obtained analytically and presented graphically for aluminum epoxy-like material. The variations of these reflection coefficients are analyzed for different values of non-local parameter, microelongational parameter, viscosity and variable thermal conductivity. The expressions of energy ratios acquired in explicit form are also represented graphically as functions of the angle of incidence in accordance with the defined rule of conservation of energy. [ABSTRACT FROM AUTHOR]

Cracks are extensively existing in rocks and play a significant role in the acoustic anisotropy of cracked rocks. Rocks in nature are affected by pore pressure, whereas the crack deformation with pore pressure and the impacts of the crack deformation on the anisotropic acoustic properties remain little known. Combining the theoretical model with the laboratory measurements of the anisotropic velocities of artificial sandstone samples with and without aligned penny‐shaped cracks, we invert for the crack parameters that characterize the crack deformation as a function of pore pressure and theoretically simulate the impacts of pore pressure–induced variation in the crack parameters on the anisotropic velocities. The results show that with increasing pore pressure, the inverted crack porosity increases exponentially, whereas the inverted crack aspect ratio decreases exponentially and the two crack parameters are linearly correlated. Moreover, model calculation demonstrates that the anisotropic velocities exhibit distinct reductions with the variation in the crack parameters caused by increasing pore pressure. In particular, the reduction in the velocity of the shear wave travelling parallel to the crack plane with polarization perpendicular to the crack plane is the most pronounced. We also demonstrate that the effects of the pore pressure–induced increasing crack porosity on the anisotropic velocities are more pronounced than the impacts of the decreasing crack aspect ratio. The findings not only reveal the variation of the crack geometry with pore pressure and the effects of the crack deformation on the anisotropic velocities of the cracked rocks but also can provide theoretical support for improving the characterization of the cracks through seismic survey. [ABSTRACT FROM AUTHOR]

In this study, two-dimensional numerical simulations of oblique detonation waves (ODWs) under a flight altitude of 10 km were performed. Because of their high importance in a zero-carbon economy, ammonia and hydrogen are considered as the fuel for aircrafts. Six cases with various hydrogen addition ratios in the fuel mixture were considered to explore the effects of hydrogen addition on the ignition structure, surface instability and NO emission of ODWs. It was found that as the hydrogen addition ratio decreases, the ODWs become more difficult to initiate with increased ignition length, and more complicated multi-wave system emerges with a second oblique detonation wave (SODW). The oblique wave angle is rarely influenced by hydrogen addition ratio. Two types of reaction surfaces, i.e. "saw-tooth" and "key-stone", along with a series of transverse waves and vortices can be observed for the case with a hydrogen addition ratio of 20% by volume in the fuel mixture. The oscillation amplitude of the reaction zone length, which quantifies the surface instability, increases with decreasing hydrogen addition ratios. The mass fraction of NO is the highest in the case with a hydrogen addition ratio of 40%. NO concentration is higher in detonation compared to that in deflagration in all cases. The pathway analysis of NO indicates that the thermal NO is the primary contributor to NO production in the cases with high hydrogen addition ratios, while the HNO pathway becomes more significant in the cases with low hydrogen addition ratios. • 2D numerical simulation of ODWs under a flight altitude of 10 km using NH3/H2 were performed. • The initiation characteristics, surface instability and NO emission of ODWs were reported. • The effects of hydrogen addition on the structure and pollutant emission of ODWs were examined. [ABSTRACT FROM AUTHOR]

The presence and extent of metastatic disease in axillary lymph nodes (ALNs) in the setting of breast cancer (BC) are important factors for staging and therapy planning. The purpose of this study was to perform a multiparametric sonographic evaluation of ALNs to better differentiate between benign and metastatic nodes. Ninety-nine patients (mean age 54.1 y) with 103 BCs were included in this study, and 103 ALNs were examined sonographically. B-mode parameters, such as size in two dimensions, shape, cortical thickness and capsule outline, were obtained, followed by vascularity assessment via colour Doppler and microflow imaging and stiffness evaluation via shear wave elastography. Postoperative histopathological evaluation was the reference standard. In the statistical analysis, logistic regression and ROC analyses were conducted to search for feature patterns of both types of ALNs to evaluate the prediction qualities of the analysed variables and their combinations. For a cortex larger than 3 mm, without a circumscribed margin of the LN capsule and SWE (E max > 26 kPa), the AUC was 0.823. Multiparametric assessment, which combined conventional US, quantitative SWE and vascularity analysis, was superior to the single-parameter approach in the evaluation of ALNs. [ABSTRACT FROM AUTHOR]

The shear-wave velocity (Vs) of soils has been acknowledged among the most critical factors affecting the nature of seismic surface motions, known as seismic site effects, in the course of probable earthquakes. Together with the one-dimensional (1D) Vs profiles of soils, the lateral heterogeneity of velocity contrasts may strongly impact seismic ground motions within the surface. Such conditions seem to occur in the city of Tehran, Iran, mainly in the eastern part, Hakimiyeh Valley, wherein alluvial deposits have been settled between the Alborz and Sepayeh (the Anti-Alborz) mountain ranges. In this resepct, the significant differences observed between previous analytical and empirical studies doubles the necessity of estimating real bedrock depth and Vs structure in this area. Given that the improper analysis of seismic site effects, using unrealistic dynamic characteristics, gives rise to the low-accuracy prediction of seismic hazards as well as significant human and financial losses; this study is an attempt to extract the two- dimensional (2D) Vs structure of the subsurface layers in the form of two north-south and east-west profiles, through the single-station and array measurements of ambient noises (viz., microtremors), as the first deep alluvial models in this area. For this purpose, the ambient noises are recorded with reference to 4 and 11 array and single-station measurements, respectively. A circular layout, comprised of two concentric circles, is further considered for the array measurements with 11 three-component narrow-band seismometers, Lennartz LE-3D/20S, within each array. The recorded array seismograms are then analyzed via the spatial autocorrelation (SPAC) method and the frequency-wavenumber (F-K) analysis, and all seismograms recorded in this line are subsequently evaluated by the time-frequency analysis (TFA) of ellipticity in the Geopsy software. Afterward, the results are utilized as the objective functions (OFs) in the inversion operation for calculating the Vs profiles at the selected stations. The neighborhood algorithm is further applied for the inversion of the OFs and the extraction of the Vs profiles. The study results as it comes to the extraction of the 2D profiles and the recognition of the Vs structure in this area, along with the velocity of 2200 m/s, correspond to the seismic bedrock located in the deepest part of the sedimentary basin, 800 m. Moreover, the underground topographies, such as faults, can be identified in the Vs profiles by means ofusing the ambient noises. As a final point, the profiles indicate that the variations in the Vs and dynamic properties of the soil are significant in this area, as one with a complicated subsurface structure. The dominant frequencies of the sediments in Hakimiyeh Valley, reported in previous analytical research, are also significantly different from that those extracted in this empirical study. As an illustration, no sharp and clear peaks can be spotted in the analytical amplification functions in Hakimiyeh Valley, while there are distinct peaks below 2 Hz at most stations in the present study. Furthermore, the study results are in good agreement with the geology of this area, and pave the ground for analytical site effect studies in the future. [ABSTRACT FROM AUTHOR]

Conclusion: We developed a detailed processing workflow that is specifically designed for acoustic FWI and RTM of DAS-VSP data obtained from a deviated well. Field data typically contain numerous noises and shear wave interference. These noises can be attenuated effectively to ensure accurate acoustic FWI results. Our proposed methodology includes a multi-channel separation approach that enables extraction of uncontaminated P-wave data. This vital step improves the effectiveness and accuracy of subsequent FWI and RTM analyses. [ABSTRACT FROM AUTHOR]

Conclusion: Affected by amplification and attenuation of the site effect, SNRs of records at the surface appear to be significantly frequency-dependent. For earthquakes with small magnitudes and epicentral distance, high-frequency S-wave and surface wave are easily identified in the underground records, and their SNRs are normally higher than the surface records. For remote earthquakes with main wave mode of low-frequency surface wave, SNRs of the surface records are higher because of amplification of the site effect. But for remote earthquakes excited by deep sources, as the main wave mode is confirmed as P-wave with frequency above 1 Hz, the underground records show as higher SNRs. Synchronous observations in HDUL show advantages in identifying small to moderate earthquakes and microearthquakes, especially the high-frequency signals above 1 Hz. [ABSTRACT FROM AUTHOR]

Earthquake early warning systems (EEWSs) are real-time seismology-based applications that purpose to reduce earthquake damage by taking some precautions for environments that are likely to be damaged. These systems are divided into two categories as on-site and regional. In this study, an on-site EEWS called ESenTRy, consisting of an accelerometer, GPS and communication components, has been designed. In this scope, a Windows operating system-based software has been developed using the.NET Framework and C# language. The developed software has the ability to read the Güralp Compressed Format strong motion data in real-time, compute the strong motion indices such as destructive intensity, real-time intensity and instrumental modified Mercalli intensity, issue an alarm in the target area and alert the defined Modbus clients. To test the reliability of ESenTRy, two simulations have been performed using the strong motion data belonging to the magnitude 7.7 Kahramanmaraş-Pazarcık earthquake that occurred in Türkiye on February 6, 2023, at 01:17:32 UTC and magnitude 5.9 Düzce-Gölyaka earthquake that occurred in Türkiye on December 23, 2022, at 01:08:15 UTC. In the test applications, depending on the distance between the stations and earthquake epicenters, the time difference between the Level-2 alarm trigger times and S-wave arrival times varied between 1.5 and 16 s, while the time difference between the Level-2 alarm trigger times and P wave arrival times varied between 0.5 and 29.5 s. The flowchart diagrams of the developed algorithm and results obtained from the simulations are presented in detail. [ABSTRACT FROM AUTHOR]

This study addresses the critical question of predicting the amplitude of S-waves during earthquakes in Aotearoa New Zealand (NZ), a highly earthquake-prone region, for implementing an Earthquake Early Warning System (EEWS). This research uses ground motion parameters from a comprehensive dataset comprising historical earthquakes in the Canterbury region of NZ. It explores the potential to estimate the damaging S-wave amplitude before it arrives, primarily focusing on the initial P-wave signals. The study establishes nine linear regression relationships between P-wave and S-wave amplitudes, employing three parameters: peak ground acceleration, peak ground velocity, and peak ground displacement. Each relationship's performance is evaluated through correlation coefficient (R), coefficient of determination (R²), root mean square error (RMSE), and 5-fold Cross-validation RMSE, aiming to identify the most predictive empirical model for the Canterbury context. Results using a weighted scoring approach indicate that the relationship involving P-wave Peak Ground Velocity (Pv) within a 3-second window strongly correlates with S-wave Peak Ground Acceleration (PGA), highlighting its potential for EEWS. The selected empirical relationship is subsequently applied to establish a P-wave amplitude (Pv) threshold for the Canterbury region as a case study from which an EEWS could benefit. The study also suggests future research exploring complex machine learning models for predicting S-wave amplitude and expanding the analysis with more datasets from different regions of NZ. [ABSTRACT FROM AUTHOR]

In order to improve the detection range and imaging resolution of dipole remote detection logging, an optimal nonlinear frequency modulation (ONLFM) excitation method is proposed in this paper. In this method, the optimal waveform model of the sound source is designed with objective functions of SNR and resolution to obtain the highest resolution under the condition of the required SNR. This optimal model is a multi-constraint optimization problem, and the simulated annealing method has been used to solve it. Solving the optimal model can obtain the optimal spectrum, and the ONLFM waveform can be designed by using the stationary phase principle. Compared with the electric pulse sound source used in traditional technology, this ONLFM sound source can improve the energy and extend the frequency band range of the reflected wave, which can provide the higher resolution and SNR. The simulation results show that the ONLFM sound source can effectively improve the SNR and resolution of the reflected wave, and the detection range and imaging resolution of dipole shear wave remote detection will be improved. [ABSTRACT FROM AUTHOR]

A review of the S‐velocity structure beneath South America, for the crust and upper mantle, is performed using a recent methodology based on Rayleigh wave analysis, and a new 3D S‐velocity model (from 0 to 400 km depth) is achieved for this study area. The precise location and structure of the asthenosphere have been both determined from this new model, which have not been obtained in other previous studies, allowing to know how the different geological units that compose South America are delimited in terms of S‐velocity and lithosphere thickness. For example, the highest S‐velocities and the thickest lithosphere of the cratonic areas, are determined at the east of the Amazonian Craton and the São Francisco Craton. The lithosphere beneath the Guyana Shield is thinner than beneath the Central Brazil Shield, and the lithospheric root of the Amazonian Craton is determined deeper than the São Francisco Craton. The lithosphere at the east of the Central Brazil Shield is the thickest (~200‐km thick). Another interesting feature depicted in terms of S‐velocity and lithosphere thickness is the Transbrasiliano Lineament, which is determined in the crust and the upper mantle, confirming that it is not just a surface feature but a deep feature. [ABSTRACT FROM AUTHOR]

On November 22, 2020, a moment magnitude of Mw 3.5 earthquake struck the highly populated Nile Delta. This event marked the first recorded earthquake in this area. We employed the polarity of P and S wave first motions, as well as SH and SV amplitudes and their respective ratios (SH/P and SV/SH), to constrain the focal mechanism solution. Furthermore, considering Brune's circular source model, kinematic source parameters were estimated through spectral analysis of available and reliable seismic data. The obtained solution reveals an oblique-slip fault mechanism, characterized by strike, dip, and rake angles of 341º, 69º, and -47º, respectively. Additionally, the two fault planes exhibit trends aligned with the E-W and NNW directions. This normal fault mechanism with a strike component aligns with previously identified events in various active areas of Egypt, indicating a dominant extensional stress regime. The trend/plunge of the P and T axes are determined to be 299º/46º and 42º/13º, respectively. Moreover, the NE trending of the T axis agrees well with the current extension stress field prevalent along the eastern border of Egypt. The average seismic moment and moment magnitude values for P and SH waves are estimated to be 1.86 × 1014 Nm, and 3.5, respectively. Furthermore, the average source values of radius and stress drop are calculated to be 304 m, and 29 bar, respectively. Through a comparative and comprehensive analysis of fault mechanism solutions in the Nile Delta region and its surroundings, we have concluded that the fault structures in the Hinge Zone and Cairo-Suez Shear Zone exhibit similarities. This finding provides evidence that the geodynamic processes and fault style are identical. In conclusion, the provided information contributes to our understanding of the seismotectonic characteristics and earthquake hazard in the epicentral region. Moreover, this study serves as a motivation for future site response and seismic hazard analyses based on a scenario-based approach. [ABSTRACT FROM AUTHOR]

Backazimuthal variations in the shear wave splitting of core-refracted shear waves (SKS, SKKS and PKS phases, jointly referred to as X KS) at the Black Forest Observatory (BFO, Southwest Germany) indicate small-scale lateral and partly vertical variations of the seismic anisotropy. However, existing anisotropy studies and models for the nearby Upper Rhine Graben (URG) area in the northern Alpine foreland are mostly based on short-term recordings and by this suffer from a limited backazimuthal coverage and averaging over a wide or the whole backazimuth range. To identify and delimit laterally confined anisotropy regimes in this region, we carry out X KS splitting measurements at six neighbouring (semi-)permanent broad-band seismological recording stations (interstation distance 10–80 km). We manually analyse long-term (partly > 20 yr) recordings to achieve a sufficient backazimuthal coverage to resolve complex anisotropy. The splitting parameters (fast polarization direction |$\phi $|⁠ , delay time |$\delta t$|⁠) are determined in a single- and multi-event analysis. We test structural anisotropy models with one layer with horizontal or tilted symmetry axis and with two layers with horizontal symmetry axes (transverse isotropy). To account for lateral variations around a single recording site, modelling is compared for the whole and for limited backazimuth ranges. Based on this, we provide a 3-D block model with spatial variation of anisotropic properties. Based on delay times > 0.3 s and missing discrepancies between SKS and SKKS phases, which do not support lower mantle anisotropy, the found anisotropy is placed in the lithosphere and asthenosphere. The spatial distribution as well as the lateral and backazimuthal variations of the splitting parameters confirm lateral and partly vertical variations in anisotropy. On the east side of the URG, we suggest two anisotropic layers in the Moldanubian Zone (south) and one anisotropic layer in the Saxothuringian Zone (north). In the Moldanubian Zone, a change of the fast polarization directions is observed between the east and the west side of the URG, indicating different textures. At the boundary between the two terranes, an inclined anisotropy is modelled which may be related with deformation during Variscan subduction. Regarding the observation of numerous null measurements and inconsistent splitting parameters, especially (southwest of BFO) in the southern URG, different hypothesis are tested: scattering of the seismic wavefield due to small-scale lateral heterogeneities, a vertical a -axis due to a vertical mantle flow related to the Kaiserstuhl Volcanic Complex, as well as a different preferred orientation of the olivine crystals (not A-type, but C-type) due to specific ambient conditions (high temperature, water content). [ABSTRACT FROM AUTHOR]

Ground motions and seismic site factors for the design and analysis of infrastructure systems are typically computed based on one-dimensional (1-D) site response analysis, assuming the ground surface is horizontal and the earthquake waves propagate vertically near the ground surface. The 1-D results may not be applicable for sloping ground surfaces and layer interfaces, and therefore, the 1-D results must be adjusted for sloping grounds. In this study, a general framework for developing seismic site factors for sloping grounds and its application for Charleston, SC is presented. The two-dimensional (2-D) site response analysis results of sloping ground were compared with the 1-D horizontal ground results to develop slope adjustment factors. A total of 385 2-D nonlinear finite element simulations of sloping grounds were performed considering seven ground inclinations, 11 shear wave velocity profiles, and five ground motions representative of the area. The results show that the surface responses computed from sloping ground analyses significantly differ from those of horizontal ground analyses. By comparing the 1-D and 2-D results, a set of slope adjustment factors was developed and expressed as an easy-to-use chart. The slope adjustment factor at a project site can be obtained from the proposed chart using site-specific VS30 and ground inclination at a selected period. [ABSTRACT FROM AUTHOR]

Shoulder dysfunction is one of the most common complications seen in patients who have undergone neck dissection surgery. The prevalence of shoulder dysfunction increases depending on the type and extent of neck dissection surgery. We aim to study the relationship between changes in intraoperative neuromonitoring (IONM) threshold during SAN stimulation, ultrasonographic measurement of muscle size and shear wave elastography with shoulder dysfunction. This is a prospective study. All patients who have undergone neck dissection in our centre have been recruited. Analysis of demographic data, IONM threshold during exposure and pre-closure, shoulder function score, neck disability index score (NDII) and ultrasonographic parameters pre-op and during follow up was done. The cohort was divided into patients who suffered from shoulder dysfunction post op (Group A) and patients with normal shoulder function post op (Group B). Statistical significance were seen in IONM threshold during SAN stimulation and Constant shoulder score for 6 months follow up in Group A. IONM threshold difference during exposure and pre-closure could effectively prognosticate shoulder dysfunction post op. A return of shoulder function could be seen in patients who suffered from shoulder dysfunction if early physiotherapy could be commenced. [ABSTRACT FROM AUTHOR]

The rupture mechanism of a seismic source governs the spatiotemporal distribution and intensity characteristics of the radiated stress-wave field and significantly affects the dynamic disasters of roadways triggered by seismic disturbances. In this study, we propose a method to simulate seismic sources with arbitrary rupture mechanisms based on moment-tensor theory. Subsequently, using the dynamic instability of tailentry at the 63upper06 working face Dongtan Coal Mine induced by an "8.30" strong mining-induced tremor as the engineering context, we calibrate the characteristics of the seismic source via moment-tensor inversion. The entire process from the excitation of the strong seismic source, the propagation of stress waves, and the eventual triggering of roadway failure and instability is simulated. Concurrently, variables representing P- and S-waves are formulated based on the relationship between the vibration and propagation directions, and the roles of both waves in the dynamic instability of the tailentry are investigated. The results indicate that (1) during the mining at the 63upper06 working face, concentrated stress is transferred to the strong seismic-source area and the advanced area of the coal wall at the tailentry, thus providing static load conditions for the occurrence of strong seismic events and the dynamic instability of the tailentry. (2) P-waves primarily exert tensile and compressive stresses along the propagation direction in the medium, thereby resulting in localized stress variations, whereas S-waves induce shear effects between adjacent wave paths because of their opposing velocity directions. (3) The "8.30" strong mining-induced tremor is characterized by tensile failure, with P-waves exhibiting the greatest intensity in the horizontal and vertical directions, and S-waves exhibiting the highest intensity at an angle of 45 ° from the seismic source, thus contributing significantly to the damage and instability of the roadway owing to the relative spatial position between the roadway and seismic source. (4) The 100 m range ahead of the coal wall at the tailentry experiences significantly greater static and dynamic disturbances compared with other areas, thus resulting in the most severe damage. Highlights: A method that can simulate seismic sources with any rupture mechanism is proposed based on moment-tensor theory. Variables representing P- and S-waves are formulated based on the relationship between the vibration and propagation directions. The effect of seismic-source rupture characteristics on the stability of a disturbed roadway is elucidated. [ABSTRACT FROM AUTHOR]

To solve the problem of low broadband multi-directional vibration control of fluid-conveying pipes, a novel metamaterial periodic structure with multi-directional wide bandgaps is proposed. First, an integrated design method is proposed for the longitudinal and transverse wave control of fluid-conveying pipes, and a novel periodic structure unit model is constructed for vibration reduction. Based on the bandgap vibration reduction mechanism of the acoustic metamaterial periodic structure, the material parameters, structural parameters, and the arrangement interval of the periodic structure unit are optimized. The finite element method (FEM) is used to predict the vibration transmission characteristics of the fluid-conveying pipe installed with the vibration reduction periodic structure. Then, the wave/spectrum element method (WSEM) and experimental test are used to verify the calculated results above. Lastly, the vibration attenuation characteristics of the structure under different conditions, such as rubber material parameters, mass ring material, and fluid-structure coupling effect, are analyzed. The results show that the structure can produce a complete bandgap of 46 Hz–75 Hz in the low-frequency band below 100 Hz, which can effectively suppress the low broadband vibration of the fluid-conveying pipe. In addition, a high damping rubber material is used in the design of the periodic structure unit, which realizes the effective suppression of each formant peak of the pipe, and improves the vibration reduction effect of the fluid-conveying pipe. Meanwhile, the structure has the effect of suppressing both bending vibration and longitudinal vibration, and effectively inhibits the transmission of transverse waves and longitudinal waves in the pipe. The research results provide a reference for the application of acoustic metamaterials in the multi-directional vibration control of fluid-conveying pipes. [ABSTRACT FROM AUTHOR]

The soil–structure interaction plays a crucial role in determining the displacement and internal forces of multi-story buildings subjected to strong ground motion. One of the critical dynamic characteristics influencing soil–structure interaction is the fundamental site period and the average shear wave velocity associated with it. This study introduces an original equation to determine these parameters. In addition, for the first time in the literature, the version of the Rayleigh method used for finding the fundamental periods of buildings is used to find the fundamental site period. The soil is modeled as an equivalent shear beam to obtain the proposed equation. The peak displacement is obtained by acting the soil mass as an external load on the equivalent shear beam. For single-layer soil, the fundamental site period is proportional to the square root of the peak displacement of the equivalent shear beam. The least squares method generalizes the proposed relation for single-layer soils to multi-layer soil profiles. Modified Finite element Transfer matrix method is used for calibration in the least squares method. The equations used in the literature and earthquake codes for determining the fundamental site period and average shear velocity are tested on various examples, and it is shown that the method proposed in this study, along with the Rayleigh method, gives better results than these equations. The performances of these two methods and the five commonly used equations are tested and compared on different soil profiles. Transfer functions, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are used for verification. For all soil profiles, the results obtained from the transfer function, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are found to be in agreement. The true percent relative error found in the results obtained with the proposed method is 4.47%. [ABSTRACT FROM AUTHOR]

The present work investigates the motion of a semi-infinite moving crack inside a semi-infinite half-space of orthotropic medium subjected to anti-plane shear wave. The crack is located at a finite depth from the surface of semi-infinite orthotropic medium. Our aim is to examine how such anisotropy and geometric parameters can be adjusted to reduce the magnitude of stress intensity factor (SIF) to control the crack propagation near the crack tip region. As mathematical tools, Fourier transformation and inverse Fourier transformation techniques are employed to convert the governing mixed boundary value problem to the well-known Weiner-Hopf equation with suitable boundary conditions. Some physical quantities such as SIF at the crack tip and crack opening displacement (COD) around the crack tip have been derived. Graphical exhibition has been carried out to show the impact of relevant parameters such as crack velocity, layer depth from the surface to crack and orthotropic material properties on SIF and COD. The numerical results show that SIF decay with crack depth from the layer. It is also observed that SIF decreases with an increase in crack velocity and finally tends to zero as crack velocity approches near SH-wave velocity. Also, the value of COD decays as we move along the damage near the crack tip along negative x-axis and finally tends to zero at the crack tip. This behavior of COD is consistent with the physical nature of the semi-infinite crack of the problem. The results are validated for isotropic material with some reported work and are well in agreement. The study of these physical quantities (SIF, COD) ensures the arrest of onset of crack expansion by monitoring geometric parameters and wave velocity to avoid fracture. [ABSTRACT FROM AUTHOR]

There are controversial findings on how projectile penetration into the human tissue can induce tissue damage. The evidence from recent experimental investigations has explained the related underlying mechanisms. To understand and simulate the exact biomechanical mechanisms of projectile penetration-induced tissue damage, we evaluated effects of two-dimensional (2D) transient stress wave propagation of 2D-functionally graded material (FGM, radial and circumferential inhomogeneity) in an infinite hollow cylinder. A periodic radial and circumferential material gradation fluctuating a constant value has been considered as the effective material properties, across the cylinder wall and the problem has been solved by implementing the graded finite element method with nonlinear Lagrangian shape functions. In contrast with other researches, the stress wave propagation for $ r $ r and $ \theta $ θ -inhomogeneity is different compared to the case in which the $ r $ r or $ \theta $ θ -inhomogeneity has been considered, separately. Moreover, this example resembles the bullet penetration in human tissue that produces stress wave propagation, resulting in unintentional trauma in human organs. For the case of 1D-FGM ( $ r $ r – inhomogeneity), the responses are pulse-like and symmetric. Finally, due to shear waves, the $ \theta $ θ -inhomogeneity has more visible effect on the stress wave propagation than $ r $ r – inhomogeneity due to shear waves, especially when the pulse collapses. [ABSTRACT FROM AUTHOR]

The present article is concerned with the reflection of plane harmonic waves in a nonlocal micropolar thermoelastic medium having void pores in the context of dual-phase-lag and Lord-Shulman models. Two sets of coupled shear waves and three sets of coupled longitudinal waves are shown to exist. When a coupled longitudinal displacement wave is made incident, the reflection coefficients of the various reflected waves and their respective energy ratios are computed analytically and the numerical computation is carried out with the help of MATLAB software. For a particular model, the influence of nonlocal, voids and micropolar parameters on the variations of reflection coefficients and energy ratios of various reflected waves is presented graphically. It is verified that during reflection phenomenon, the sum of energy ratios is equal to unity at each angle of incidence. A comparison between the dual-phase-lag model and Lord-Shulman model is also depicted graphically. [ABSTRACT FROM AUTHOR]

We present the results of seismic profiling aimed to characterize the structure of shallow formation in the Geoncheon Valley (GCV), an area we interpreted as the north tip of the Miryang Fault This profile was deployed in the GCV, near the City of Gyeongju, Republic of Korea. The Miryang Fault is one of the major faults of the Yangsan Fault System in the Cretaceous Gyeongsang Basin, the southeastern Korean Peninsula. Despite local earthquake records showing scattered micro-seismicity along the trace of Miryang Fault, other geophysical and geological information is rare. The location of the GCV is tectonically critical: it is on the major stratigraphic boundary in the Cretaceous Gyeongsang Basin: the Hayang Group (dominantly sedimentary rocks) to the north and Yucheon Group (volcanic and volcanoclastic rocks) to the south. The surface expression of the Miryang Fault in this area is difficult to define by geomorphology since the surface is covered by highly altered cultivated farmlands. We tackle this problem by conducting seismic profiling. On a 1,200-m long linear profile, we deployed a dense array using 3-component seismic sensors and acquired both passive and active seismic data. The passive seismic data acquisition lasted about 12 days. At the end of the deployment period directly before withdrawing the array, an active survey using a sledgehammer source was also conducted. The integrated seismic cross-section displays significant segmentation in the texture of the seismic image, the sediment-bedrock interface is between less than 10 meters to slightly greater than 20 meters with a general trend of dipping to the southeast. The preliminary seismic results suggest that it is likely the Miryang Fault terminates inside the GCV, and the type of tip damage zone appears to be a group of horsetail splays. [ABSTRACT FROM AUTHOR]

Mechanical stiffness derived from force-elongation curves is fundamentally different from shear wave (SW) elastography-based tissue properties. We compared these techniques, with a total of five methods of assessing Achilles tendon (AT) stiffness. Seventeen participants (12 male and 5 female) with unilateral AT rupture performed submaximal contractions at 30% and 10% maximal isometric contraction torque of the un-injured limb. SW velocity was acquired at rest. Force-elongation curves were assessed from the free AT and the medial gastrocnemius (MG) tendon. Mechanical stiffness was determined near the end of the linear region of the force-elongation curve and from the toe region. Bivariate correlations between mechanical stiffness and SW velocity, as well as pairwise t -tests between limbs, were computed. In the injured limb, SW velocity correlated with MG tendon and free AT toe-region stiffness during 10% (r = 0.59, p = 0.020 and r = 0.60, p = 0.011, respectively) and 30% of submaximal contractions (r = 0.56, p = 0.018 and r = 0.67, p = 0.004, respectively). The un-injured limb showed no associations. In both limbs pooled together, SW velocity correlated with MG tendon toe-region stiffness in 30% of submaximal contractions (r = 0.43, p = 0.012). Free tendon mechanical stiffness was lower in the injured limb, with a mean difference of 148.5 Nmm⁻¹ (95% CI: 35.6–261.3, p = 0.013), while SW velocity was higher in the injured limb (1.67 m × s⁻¹, 95% CI; -2.4 to -0.9, p < 0.001). SW elastography may reflect AT viscoelastic properties at the initial slope of the force-length curve with strains <1% but cannot offer insight into AT mechanics at higher loads. Extended toe regions in the injured limb could have caused the association between mechanical stiffness and SW-based stiffness. [ABSTRACT FROM AUTHOR]

In order better to evaluate the brittleness of tight reservoir, some studies were conducted to build the new prediction method of brittleness index. First, mechanical properties of tight formation are obtained by triaxial mechanical tests. Subsequently, the correlation analysis between brittleness index and logging parameters was conducted to determine the potential sensitive parameters to brittleness index. Then, based on grey correlation, the initial sequence of sensitive parameters was determined and normalized. On this basis, based on the analytic hierarchy process, the two-two comparison judgment matrix of sensitive parameters was built, the weight vector was determined. Finally, the relationship model between the brittle index and sensitive parameter was established, which meant that a new prediction model of brittleness index was established. Compared with experiment measurement and elastic parameters methods, new method could also have high precision, and reflect the brittleness of reservoir, moreover not depending on the shear wave logging. Therefore, new method provides a new idea for predicting brittleness index and guidance for reservoir fracturing. [ABSTRACT FROM AUTHOR]

The effects of phase shift (δ) between compression and shear waves, and consolidation stress ratio (Kc) on the liquefaction resistance of sand under simultaneous compression and shear wave loading is investigated using a hollow cylinder torsional shear apparatus. The differences caused by prior stress history (assessed using drained versus undrained preshear) highlight the importance of test protocols in undertaking research to explore the effects of complex dynamic loading paths. The liquefaction resistance of sand was highly dependent on the loading path. However, it was not affected much by variations in δ , if the horizontal shear stress ratio (τzθ/σmc′) and the ratio between shear stress increment and normal stress increment (ΔS/ΔN) were held constant. In tests with constant cyclic stress ratio (CSR), an increase in δ decreases the cyclic resistance because the increase in δ causes a reduction in the rate of deviatoric stress increment per degree of principal stress rotation. At a given CSR , for δ≠0 cases, a change in ΔS/ΔN does not affect the liquefaction resistance of sand because the magnitude and pattern of rotation is not affected much by ΔS/ΔN (for the ratios explored in this research). Increasing Kc or static shear stress ratio (αst) increased the cyclic resistance of the tested sand for ΔS/ΔN<1. The rate of increase in cyclic resistance with increasing αst decreases with the increase in ΔS/ΔN and was essentially unchanged for ΔS/ΔN=1. This observation, that the rate of increase in cyclic resistance with αst decreases with increasing ΔS/ΔN , is consistent with the observation in the literature that the cyclic triaxial loading yields higher static shear stress correction factor (Kα) than cyclic simple shear in loose sand. [ABSTRACT FROM AUTHOR]

Magnetic resonance elastography (MRE) is a rapidly developing medical imaging technique that allows for quantitative assessment of the biomechanical properties of the tissue. MRE is now regarded as the most accurate noninvasive test for detecting and staging liver fibrosis. A two-dimensional (2D MRE) acquisition version is currently deployed at >2000 locations worldwide. 2D MRE allows for the evaluation of the magnitude of the complex shear modulus, also referred to as stiffness. The development of 3D vector MRE has enabled researchers to assess the biomechanical properties of small organs where wave propagation cannot be adequately analyzed with the 2D MRE imaging approach used in the liver. In 3D vector MRE, the shear waves are imaged and processed throughout a 3D volume and processed with an algorithm that accounts for wave propagation in any direction. Additionally, the motion is also imaged in x, y, and z directions at each voxel, allowing for more advanced processing to be applied. This review describes the technical principles of 3D vector MRE, surveys its clinical applications in small organs, and discusses potential clinical significance of 3D vector MRE. 3D vector MRE is a promising tool for characterizing the biomechanical properties of small organs such as the uterus, pancreas, thyroid, prostate, and salivary glands. However, its potential has not yet been fully explored. [Display omitted] • 3D Vector MRE has high clinical potential for the assessment of small organs. • 3D Vector MRE of the uterus, pancreas, thyroid, prostate, and parotid is feasible. • 3D Vector MRE provides information on the biomechanical properties of small organs. • 3D Vector MRE helps to differentiate between healthy and pathological tissue. • More research is needed to optimize the performance of 3D Vector MRE in small organs. [ABSTRACT FROM AUTHOR]

Volcanic oil and gas resources are abundant and have been one of the principal focuses of research in the oil and gas industry for a long time. Due to the complexity of the volcanogenesis and the non-homogeneity of the reservoir, the construction of a reasonable volcanic rock petrophysical model to guide the reservoir prediction is the key to success or failure. Unlike conventional sedimentary reservoirs, volcanic rock skeletons have diverse mineralogical compositions and pore structures, making the construction of equivalent petrophysical models highly complicated. This paper proposes a method to construct equivalent petrophysical models of complicated volcanic rocks with multiple mineral components and pore structures utilizing conventional logging curves. In the middle basal volcanic rock development area of the Songnan Fault, the errors in mineral content calculation and transverse wave estimation are less than 10% when comparing the results of elemental capture spectroscopy (ECS) logging and core test analysis; meanwhile, it directs the volcanic rock phase-controlled pre-stack inversion work and upgrades the accuracy of volcanic rock well seismic multi-scale reservoir prediction. [ABSTRACT FROM AUTHOR]

Time–frequency analysis methods represent an efficacious approach to process data derived from full-waveform acoustic logging. This research proposes a coupled time–frequency analysis method that synergistically incorporates ensemble empirical mode decomposition, fractional Fourier transform, Choi–Williams (CW) distribution and adaptive filtering. This coupled method facilitates the comprehensive analysis of full-waveform acoustic logging signals within rigid geological formations. Specifically, it is designed to explore the time–frequency characteristics of shear wave (S-wave) within the context of igneous reservoirs. The coupled time–frequency analysis method significantly ameliorates the time–frequency coupling phenomenon of full-waveform acoustic logging signal. This coupled method is applied across different wells to confirm its wide-ranging applicability and study the time–frequency characteristics response of S-wave through the information of the peak time of the S-wave, the main frequency and the amplitude of the CW distribution. [ABSTRACT FROM AUTHOR]

Two massive earthquakes hit Turkey on February 6, 2023. The first occurred at around 4 a.m. local time and the other at around midday. The quakes affected almost ten cities and around thirteen million people. Unfortunately, the number of casualties increased with time. These earthquakes reminded us of the importance of the determination of the magnitude of an earthquake in a couple of minutes with as high accuracy as possible, which is vital for the people who live in the epicenter area. Governmental institutes must announce the magnitude of an earthquake quickly if it is huge to start a response action. This study shows the quality and efficiency of the technique that calculates the P-wave moment magnitude (Mwp) using local (strong-motion records), regional and teleseismic (velocity records) waveforms recorded at seismic stations located at different epicentral distances. The disadvantage of determining the time window for calculations was resolved with this study using calculated P-wave velocity and theoretically determined S-wave arrival times depending on the regional and teleseismic waveforms' onset and epicentral distance. The Mwp magnitude has been calculated as 7.9 using regional and teleseismic waveforms for events one and two, whereas 7.7 and 7.6 with strong-motion waveforms for events one and two, respectively, are compatible with Global Centroid Moment Tensor (GCMT) magnitude 7.8 and 7.7 for events one and two. The results of this study clearly show that an earthquake research institute should evaluate all the seismic waveforms recorded at different epicentral distances to get a confidential magnitude value considering destructive events, which is possible with data sharing through global networks at present. [ABSTRACT FROM AUTHOR]

The damage evolution process of layered rock is influenced by its fine structure, lamination direction, and confining pressure, exhibiting significant anisotropic characteristics. This study focuses on shale as the research object, employing indoor tests and theoretical analysis to define damage variables and initial damage based on ultrasonic wave velocity. This research investigates the damage evolution law of layered rock under varying confining pressures and dip angles. The findings reveal that damage variables defined using transverse wave velocity effectively reflect the damage evolution process. Additionally, confining pressure significantly affects damage evolution, with increasing pressure causing a rightward shift in the damage variable–strain curve and an increase in initial damage. The slab inclination angle also influences damage evolution; samples with 45° and 60° inclinations are more susceptible to damage, with initial damage showing a trend of increasing and then decreasing. To accurately describe the relationship between damage variables and strain during the loading process, this paper establishes a segmented damage evolution equation characterized by wave velocity. Initially, an inverse proportional function is employed to characterize the strain before crack closure. Subsequently, a logistic function represents the curve from crack strain to peak strain. This combined approach provides a comprehensive depiction of the damage evolution. This study underscores the importance of considering confining pressure and laminar inclination in the analysis of rock stability and integrity. These results provide critical insights into the damage evolution characteristics of layered rocks, offering valuable references for engineering safety assessments. [ABSTRACT FROM AUTHOR]

Today, geomechanics plays a crucial role in the oil industry, particularly in enhancing production and ensuring well stability. To achieve optimal results, accurate estimation of geomechanical parameters is essential. One of the low-cost and accurate methods for estimating geomechanical parameters is the use of intelligent methods. In this research, geomechanical parameters are estimated using conventional data logs using intelligent methods. The aim of this study is to introduce a new machine learning algorithm to estimate geomechanical parameters using conventional data logs in one of the hydrocarbon field wells in southwest Iran. In this article, the shear wave velocity and uniaxial compressive strength (UCS) were estimated using machine learning algorithms. Subsequently, other geomechanical parameters were calculated based on these estimated parameters derived from machine learning algorithms. For shear wave velocity (Vs) prediction using MLP and CLM (CNN+LSTM+MLP) algorithms, First, effective features were selected using the Auto-encoder deep learning algorithm. The selected features for Vs input into the algorithms were Vp, RHOB, CALIPER, and NPHI, and then the Vs is estimated with MLP and CLM algorithm. To evaluate the results, the model was assessed using metrics such as MAE, MAPE, MSE, RMSE, NRMSE, and R2 on the train, test, and blind datasets. The CLM algorithm consistently demonstrated superior performance across all datasets, including training, testing, and blind data sets. The R2 values for blind data were $R_{MLP}^2 = 0.8727,$ R M L P 2 = 0.8727 , $R_{CLM}^2 = 0.9274$ R C L M 2 = 0.9274 , respectively. These outputs are crucial for estimating subsequent studies. Next, Elastic Young's moduli and Poisson's ratio were calculated, and the dynamic brittleness index was computed using dynamic Young's modulus and Poisson's ratio. Subsequently, UCS values were predicted using machine learning algorithms. Since there were 12 laboratory core samples of UCS available, UCS was initially calculated using relevant empirical relations and data from some available well logs. This process aimed to extrapolate these core results to cover the entire target depth range from 3551.072 to 3799.789 m. Subsequently, a relationship between UCS derived from well logs and laboratory results was established for the depths corresponding to where the laboratory samples were recorded. Following that, an autoencoder deep network was utilized to select effective features for predicting UCS. The selected features for UCS input into the algorithms were Vp, RHOB, and CALIPER. Subsequently, UCS was estimated using MLP and CLM algorithms. To evaluate the results, the model performance was assessed using metrics such as MAE, MAPE, MSE, RMSE, NRMSE, and R2 on the train, test, and blind datasets. Furthermore, the results were checked and evaluated using a set of statistical measures calculated for the train, test, and blind datasets, that $ R_{MLP}^2 = 0.9305, R_{CLM}^2 = 0.9953 $ R M L P 2 = 0.9305 , R C L M 2 = 0.9953 were obtained for blind UCS data. The results demonstrate that CLM achieves high accuracy in estimating these parameters, with deep learning algorithms showing higher determination coefficients and lower errors compared to MLP. Furthermore, UCS and tensile strength were calculated, followed by the computation of static brittleness index. The relationship between dynamic and static brittleness index was also investigated. Overall, the findings indicate that machine learning algorithms are robust and accurate methods for estimating Vs, UCS, and other geomechanical parameters using conventional logs. [ABSTRACT FROM AUTHOR]

S-net is a seafloor observation network for earthquakes and tsunamis around the Japan Trench, comprising 150 observatories with seismometers and pressure gauges. The region has been known to experience massive earthquakes, and several magnitude 6 and 7 class earthquakes have occurred after the network was established in 2016. This study constructed ground motion prediction equations (GMPEs) for horizontal peak ground accelerations (PGAs) and peak ground velocities (PGVs) using the S-net data and revealed that the GMPEs can be used to predict the PGAs and PGVs at the land stations where measured S-wave velocities are available. We used a relatively short time window of the S-net records from the viewpoint of earthquake early warning but included S waves. Data from earthquakes of magnitudes between Mw 5.5 and Mw 7.4 were used. The construction of the GMPEs was achieved in two steps. First, regression analysis was conducted for each event data, and mean site residual was obtained over the available records at each S-net site. Second, the data were adjusted by the mean site residuals, and stratified regression analysis, which decouples the source and path factors, was performed. Finally, we applied the GMPEs to predict PGAs and PGVs at the KiK-net sites on land. We determined that the residuals at the KiK-net sites were systematically biased with Vs30 (average S-wave velocity in the upper 30 m). We obtained correction factors for the bias and demonstrated that the PGAs and PGVs at the KiK-net sites could be predicted reasonably well. [ABSTRACT FROM AUTHOR]

Background: Right ventricle impairment (RVI) is common during acute respiratory distress syndrome (ARDS) in adults and children, possibly mediated by the level of transpulmonary pressure (PL). We sought to investigate the impact of the level of PL on ARDS-associated right ventricle impairment (RVI). Methods: Adults and children (> 72 h of life) were included in this two centers prospective study if they were ventilated for a new-onset ARDS or pediatric ARDS, without spontaneous breathing and contra-indication to esophageal catheter. Serial measures of static lung, chest wall, and respiratory mechanics were coupled to critical care echocardiography (CCE) for 3 days. Mixed-effect logistic regression models tested the impact of lung stress (ΔPL) along with age, lung injury severity, and carbon dioxide partial pressure, on RVI using two definitions: acute cor pulmonale (ACP), and RV dysfunction (RVD). ACP was defined as a dilated RV with septal dyskinesia; RVD was defined as a composite criterion using tricuspid annular plane systolic excursion, S wave velocity, and fractional area change. Results: 46 patients were included (16 children, 30 adults) with 106 CCE (median of 2 CCE/patient). At day one, 19% of adults and 4/7 children > 1 year exhibited ACP, while 59% of adults and 44% of children exhibited RVD. In the entire population, ACP was present on 17/75 (23%) CCE. ACP was associated with an increased lung stress (mean ΔPL of 16.2 ± 6.6 cmH2O in ACP vs 11.3 ± 3.6 cmH2O, adjusted OR of 1.33, CI95% [1.11–1.59], p = 0.002) and being a child. RVD was present in 59/102 (58%) CCE and associated with lung stress. In children > 1 year, PEEP was significantly lower in case of ACP (9.3 [8.6; 10.0] cmH2O in ACP vs 15.0 [11.9; 16.3] cmH2O, p = 0.03). Conclusion: Lung stress was associated with RVI in adults and children with ARDS, children being particularly susceptible to RVI. Trial registration Clinical trials identifier: NCT0418467. [ABSTRACT FROM AUTHOR]

In this study, the propagation of plane waves in the lanthanum gallium tantalate (langatate, LGT) single crystals is investigated. Moreover, the flight time of different waves in the LGT rectangular parallelepiped sample is measured using the ultrasonic pulse‐echo (UPE) technique, and the elastic constants of the LGT sample are determined. The experimental results clearly show echoes corresponding to the longitudinal and transverse waves along the x‐axis. The waves along the z‐axis have a similar property. However, the waves along the y‐axis are more complex than those along the x‐ and z‐axes. The echoes corresponding to the quasi‐longitudinal waves along the y‐axis are clear, but those corresponding to the transverse and quasi‐transverse waves along the y‐axis are not. The elastic constant can be accurately determined if the wave echoes corresponding to this constant propagate without distinct distortion and are clear; otherwise, it may be impossible to accurately determine the constant using UPE. All elastic constants cijE$c_{ij}^{\mathrm{E}}$ except c13E$c_{13}^{\mathrm{E}}$ of the LGT single crystals can be determined using UPE from one sample. This study uses UPE to provide a reference for the characterization of elastic constants of piezoelectric crystals with 32 symmetry from one sample. [ABSTRACT FROM AUTHOR]

Purpose: A retrospective study was conducted to determine the value of shear wave elastography (SWE) and red blood cell distribution width (RDW) in the diagnosis of various forms of erectile dysfunction (ED). Methods: With the method of Nocturnal Penile Tumescence and Rigidity (NPTR) and the screening method of Color Duplex Doppler Ultrasound (CDDU), hematological data were collected from 131 individuals, among whom 24 are with psychogenic ED, 48 are with non-arterial ED(NAED) and 59 are with arterial ED(AED) with erectile dysfunction. SWE value of penile corpus cavernosum(CCP) and cavernous arterial flow velocity were measured before (flaccid state) and after (erect state) intracavernous injection (ICI) in all patients. Results: Among the AED patients and other types of ED patients, there were statistically significant differences in the abridged five-item International Index of Erectile Function (IIEF-5), red blood cell distribution width-coefficient of variation (RDW-CV), red blood cell distribution width-standard deviation (RDW-SD), and SWE values (all P < 0.01). In the AED patients, the IIEF-5 scores had a significant negative relationship with RDW-CV, RDW-SD, and SWE values, with SWE values having the strongest correlation. (p < 0.001, r=-0.638). Conclusion: The combination of RDW level and SWE value demonstrated the greatest performance in diagnosing AED, according to the receiver-operator characteristic(ROC) curve analysis (AUC = 0.870, p < 0.0001, cut-off value of 0.75, sensitivity of 74.6%, specificity of 91.7%).RDW and SWE value may develop into an incredibly simple, practical tool for predicting and diagnosing AED. Trial registration: retrospectively registered. [ABSTRACT FROM AUTHOR]

Background: Sentinel lymph node metastasis (SLNM) is a critical factor in the prognosis and treatment planning for breast cancer (BC), as it indicates the potential spread of cancer to other parts of the body. The accurate prediction and diagnosis of SLNM are essential for improving clinical outcomes and guiding treatment decisions. Objective: This study aimed to construct a Lasso regression model by integrating multimodal ultrasound (US) techniques, including US, shear wave elastography (SWE), and contrast-enhanced ultrasound (CEUS), to improve the predictive accuracy of sentinel lymph node metastasis in breast cancer and provide more precise guidance for clinical treatment. Results: A total of 253 eligible samples were screened, of which 148 were group benign and 105 were group malignant. There were statistically significant differences (p < 0.05) between group malignant patients in terms of age, palpable mass, body mass index, distance to nipple, maximum diameter, blood flow, microcalcification, 2D border, 2D morphology, and 2D uniformity and group benign. The Lasso regression model was useful in the diagnosis of benign and malignant nodules with an AUC of 0.966 and in diagnosing SLNM with an AUC of 0.832. Conclusion: In this study, we successfully constructed and validated a Lasso regression model based on the multimodal ultrasound technique for predicting whether SLNM occurs in BCs, showing high diagnostic accuracy. [ABSTRACT FROM AUTHOR]

In order to enhance the development efficiency of thick and complex carbonate reservoirs in the Middle East, a case study was conducted on M oilfield in Iraq. This study focused on reservoir characterization, injection-production modes, well pattern optimization, and other related topics. As a result, key techniques for the high-efficiency development of thick carbonate reservoirs were established. The research findings include the following: (1) the discovery of hidden "low-velocity" features within the thick gypsum-salt layer, which led to the development of a new seismic velocity model; (2) the differential dissolution of grain-supported limestones is controlled by lithofacies and petrophysical properties, resulting in the occurrence of "porphyritic" phenomena in core sections. The genetic mechanism responsible for reversing petrophysical properties in dolostones is attributed to "big hole filling and small hole preservation" caused by dense brine refluxing; (3) fracture evaluation technology based on anisotropy and dipole shear wave long-distance imaging was developed to address challenges associated with quantitatively assessing micro-fractures; (4) through large-scale three-dimensional physical models and numerical simulations, it was revealed that water–oil displacement mechanisms involving "horizontal breakthrough via hyper-permeability" combined with vertical differentiation due to gravity occur in thick and heterogeneous reservoirs under spatial injection-production modes; (5) a relationship model linking economic profit with well pattern density was established for technical service contracts in the Middle East. Additionally, an innovative stepwise conversion composite well patterns approach was introduced for thick reservoirs to meet production ramp-up requirements while delaying water cut rise; (6) a prediction technology for the oilfield development index, considering asphaltene precipitation, has been successfully developed. These research findings provide robust support for the efficient development of the M oilfield in Iraq, while also serving as a valuable reference for similar reservoirs' development in the Middle East. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate salivary gland involvement in patients with anti-centromere antibody (ACA)-positive primary Sjögren's syndrome (pSS). We retrospectively evaluated 134 patients with pSS. Patients were divided into four groups based on the results of ACA and SSA antibodies. We compared clinical manifestations, laboratory findings, salivary gland shear wave elastography, minor salivary gland biopsy results, and EULAR Sjögren's syndrome disease activity index (ESSDAI) scores among the four groups. A total of 134 patients were classified as having pSS and divided into three groups based on serum ACA and anti-SSA antibody status: ACA + SSA + , ACA + SSA-, ACA-SSA + , and seronegative. The primary analysis focused on comparing the clinical and SWE findings between the ACA + SSA + and ACA + SSA- groups. In the double-positive group, SWE revealed fewer minor salivary glands along with higher mean (Emean) and maximum (Emax) values of Young's moduli than those in the ACA-negative group. Patients in the positive group had increased occurrence of Raynaud's phenomenon, liver involvement, and a higher incidence of malignancy (P < 0.05). ACA-positive pSS patients are a subgroup with different clinical manifestations and more pronounced involvement of the minor salivary glands. SWE findings revealed that ACA-positive patients exhibit significantly higher mean and maximum stiffness values compared to ACA-negative patients, indicating more extensive glandular fibrosis and involvement. These results underscore the utility of SWE as a valuable method for evaluating salivary gland pathology and supporting the stratification of pSS patients. [ABSTRACT FROM AUTHOR]

Background: Two-dimensional (2-D) shear wave elastography is a commonly used sonographic elastography method for the noninvasive measurement of liver stiffness. There is little liver stiffness data available in the pediatric population and its association with the child's weight is scarce. Objective: The principal aim of our study was to determine weight-specific reference liver stiffness values in a pediatric population free of liver disease. Materials and methods: In this retrospective single-center study, 2-D shear wave elastography values were recorded in children with no history of liver disease and with a clinically indicated ultrasound examination, between April 2021 and July 2022. Examinations were performed using an Aplio i800 and two Aplio a450 (Canon Medical Systems), with a convex probe (i8CX1 or 8C1 transducers). This population was divided into ten weight groups. We evaluated the relation between weight and liver elasticity values and compared right and left lobe measurements. Results: During the period of the study, 235 children were included. We then excluded 64 patients (weight not available = 13, interquartile range to median ratio (IQR/M) greater than 30% = 51). On the final sample (171 patients, median age 6.5 years [0–18], median weight 22.6 kg [2.5–80]), stiffness values showed a global significant trend to increase with weight. In each group, there was no significant difference between right and left liver stiffness values. The mean normal liver stiffness value including all children was 5.3 ± 1.1 kPa. Conclusion: Liver stiffness in our pediatric sample with no history of liver disease increases with weight. These data may help to distinguish normal from pathological elastography values. [ABSTRACT FROM AUTHOR]

The superconducting quantum interference (SQI) patterns of Josephson junctions fabricated from hybrid structures that interface an s-wave superconductor with a topological insulator can be used to detect signatures of novel quasiparticle states. Here, we compare calculated and experimental SQI patterns obtained from hybrid junctions fabricated on cadmium arsenide, a two-dimensional topological insulator. The calculations account for the effects of Abrikosov (anti-) vortices in the superconducting contacts. They describe the experimentally observed deviations of the SQI from an ideal Fraunhofer pattern, including anomalous phase shifts, node lifting, even/odd modulations of the lobes, irregular lobe spacing, and an asymmetry in the positive/negative magnetic field. We also show that under a current bias, these vortices enter the electrodes even if there is no intentionally applied external magnetic field. The results show that Abrikosov vortices in the electrodes of the junctions can explain many of the observed anomalies in the SQI patterns of topological insulator Josephson junctions. [ABSTRACT FROM AUTHOR]

In this paper, we have employed HQET to determine the masses of radially excited (n = 2) S-wave charm and bottom baryons. The HQET Lagrangian containing the non-perturbative parameters is shown with heavy baryon fields. The non-perturbative parameters, couplings, and decay widths are also studied for the S-wave singly heavy baryons. The HQET parameters Λ ¯ , λ 1 and λ 2 are calculated for the ground state (n = 1) using the masses of S-wave baryons. The 1 S mass short-distance mass scheme is employed to estimate the heavy quark masses and non-perturbative parameters. The mass term ratios of n = 1 and n = 2 mesons and baryons containing parameters Λ ¯ and λ 1 are studied by varying the bottom quark mass. This analysis shows that heavy quarks behave the same inside mesons and baryons in both 1S and 2S states. The HQET symmetry of Λ ¯ is used to find the parameters and masses for n = 2 S-wave baryons. The variation of mass of 2S baryons with the non-perturbative parameters λ 1 and λ 2 is discussed. The Regge trajectories are also plotted in the (n , M 2) plane using masses of n = 1 and 2 charm and bottom baryons. The Regge trajectories are parallel and equidistant lines in the (n , M 2) plane. We have also studied the strong decays of charm and bottom baryons for both n = 1 and n = 2 states. We have estimated the coupling constants g 1 = 0. 9 1 3 − 0. 0 1 7 + 0. 0 1 0 and g 2 = 0. 5 5 9 − 0. 0 1 0 + 0. 0 0 6 for n = 1 , and g ̃ 1 g ̃ 2 = 1. 5 2 for n = 2. We have also shown the semi-electronic decay rates of charm baryons in the spectator heavy quark approximation for 1 S → 1 S , 2 S → 1 S , and 2 S → 2 S transitions. The decay rates for 1 S → 1 S transitions are of the same order as 2 S → 2 S transitions. This analysis agrees well with the available theoretical and experimental data. [ABSTRACT FROM AUTHOR]

Objectives: This study aimed to explore the performance of a model based on Chinese Thyroid Imaging Reporting and Data Systems (C-TIRADS), clinical characteristics, and shear wave elastography (SWE) for the prediction of Bethesda I thyroid nodules before fine needle aspiration (FNA). Materials and Methods: A total of 267 thyroid nodules from 267 patients were enrolled. Ultrasound and SWE were performed for all nodules before FNA. The nodules were scored according to the 2020 C-TIRADS, and the ultrasound and SWE characteristics of Bethesda I and non-I thyroid nodules were compared. The independent predictors were determined by univariate analysis and multivariate logistic regression analysis. A predictive model was established based on independent predictors, and the sensitivity, specificity, and area under the curve (AUC) of the independent predictors were compared with that of the model. Results: Our study found that the maximum diameter of nodules that ranged from 15 to 20 mm, the C-TIRADS category <4C, and Emax <52.5 kPa were independent predictors for Bethesda I thyroid nodules. Based on multiple logistic regression, a predictive model was established: Logit (p) = -3.491 + 1.630 × maximum diameter + 1.719 × C-TIRADS category + 1.046 × Emax (kPa). The AUC of the model was 0.769 (95% CI: 0.700-0.838), which was significantly higher than that of the independent predictors alone. Conclusion: We developed a predictive model for predicting Bethesda I thyroid nodules. It might be beneficial to the clinical optimization of FNA strategy in advance and to improve the accurate diagnostic rate of the first FNA, reducing repeated FNA. [ABSTRACT FROM AUTHOR]