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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]

Background: Colorectal cancer is the third most common tumour entity in the world and up to 50% of the patients develop liver metastases (CRLM) within five years. To improve and personalize therapeutic strategies, new diagnostic tools are urgently needed. For instance, biomechanical tumour properties measured by magnetic resonance elastography (MRE) could be implemented as such a diagnostic tool. We postulate that ex vivo MRE combined with histological and radiological evaluation of CRLM could provide biomechanics-based diagnostic markers for cell viability in tumours. Methods: 34 CRLM specimens from patients who had undergone hepatic resection were studied using ex vivo MRE in a frequency range from 500 Hz to 5300 Hz with increments of 400 Hz. Single frequency evaluation of shear wave speed and wave penetration rate as proxies for stiffness and viscosity was performed, along with rheological model fitting based on the spring-pot model and powerlaw exponent α, ranging between 0 (complete solid behaviour) and 1 (complete fluid behaviour). For histological analysis, samples were stained with H&E and categorized according to the degree of regression. Quantitative histologic analysis was performed to analyse nucleus size, aspect ratio, and density. Radiological response was assessed according to RECIST-criteria. Results: Five samples showed major response to chemotherapy, six samples partial response and 23 samples no response. For higher frequencies (> 2100 Hz), shear wave speed correlated significantly with the degree of regression (p ≤ 0.05) indicating stiffer properties with less viable tumour cells. Correspondingly, rheological analysis of α revealed more elastic-solid tissue properties at low cell viability and major response (α = 0.43 IQR 0.36, 0.47) than at higher cell viability and no response (α = 0.51 IQR 0.48, 0.55; p = 0.03). Quantitative histological analysis showed a decreased nuclear area and density as well as a higher nuclear aspect ratio in patients with major response to treatment compared to patients with no response (all p < 0.05). Discussion: Our results suggest that MRE could be useful in the characterization of biomechanical property changes associated with cell viability in CRLM. In the future, MRE could be applied in clinical diagnosis to support individually tailored therapy plans for patients with CRLM. [ABSTRACT FROM AUTHOR]

Over the past decades, surface wave methods have been routinely employed to retrieve the physical characteristics of the first tens of meters of the subsurface, particularly the shear wave velocity profiles. Traditional methods rely on the application of the multichannel analysis of surface waves to invert the fundamental and higher modes of Rayleigh waves. However, the limitations affecting this approach, such as the 1D model assumption and the high degree of subjectivity when extracting the dispersion curve, motivate us to apply the elastic full‐waveform inversion, which, despite its higher computational cost, enables leveraging the complete information embedded in the recorded seismograms. Standard approaches solve the full‐waveform inversion using gradient‐based algorithms minimizing an error function, commonly measuring the misfit between observed and predicted waveforms. However, these deterministic approaches lack proper uncertainty quantification and are susceptible to get trapped in some local minima of the error function. An alternative lies in a probabilistic framework, but, in this case, we need to deal with the huge computational effort characterizing the Bayesian approach when applied to non‐linear problems associated with expensive forward modelling and large model spaces. In this work, we present a gradient‐based Markov chain Monte Carlo full‐waveform inversion where we accelerate the sampling of the posterior distribution by compressing data and model spaces through the discrete cosine transform. Additionally, a proposal is defined as a local, Gaussian approximation of the target density, constructed using the local Hessian and gradient information of the log posterior. We first validate our method through a synthetic test where the velocity model features lateral and vertical velocity variations. Then we invert a real dataset from the InterPACIFIC project. The obtained results prove the efficiency of our proposed algorithm, which demonstrates to be robust against cycle‐skipping issues and able to provide reasonable uncertainty evaluations with an affordable computational cost. [ABSTRACT FROM AUTHOR]

The Eastern Himalayan Syntaxis (EHS) serves as a natural laboratory for the study of intense continental collision and lateral extrusion tectonics. By aiming at the intricate tectonic dynamics south and southeast of the EHS, we integrate seismic data from new broadband stations in central Myanmar with permanent stations in southeastern Tibet to establish a high‐resolution 3‐D shear wave velocity model through ambient noise surface wave tomography. Our imaging results reveal distinct differences in crustal seismic velocity structures between the West Burma Block, Chuan‐Dian Block, and the Shan Plateau, highlighting the extent of oblique subduction and restricted crustal extrusion. Notably, two north‐south oriented low‐velocity zones in the mid‐to‐lower crust of southeastern Tibet are mainly confined within the Chuan‐Dian Block and terminate near the Red River Fault, with limited extension into the Shan Plateau. Plain Language Summary: The Eastern Himalayan Syntaxis (EHS) marks the point where the Indian and Asian plates collide most intensely in the eastern Himalayas. Geoscientists have observed significant mountain‐building activities around the EHS extending into southeastern Tibet (SE Tibet), driven by the intense collision of these continental plates. In SE Tibet, materials are squeezed sideways, a process known as lateral extrusion due to the collision of these plates. This is evident from seismic studies showing slower wave speeds in two distinct regions of the middle to lower crust. We analyzed seismic data from new stations in central Myanmar and permanent stations in SE Tibet to better understand the zone transitioning from intracontinental collision to lateral extrusion. Using a technique called ambient noise tomography, we developed a high‐resolution 3‐D model of the crust and uppermost mantle. Our findings reveal significant differences in the crust's structure between areas of subduction, extrusion, and transition, enhancing our understanding of the geodynamic processes beneath the EHS and its surrounding areas. Particularly, two slow‐speed belts related to the lateral extrusion are confined within SE Tibet, supporting a model of limited crustal extrusion. Key Points: We obtain an integrated 3‐D Versus model by ambient noise tomography based on the data from both central Myanmar and southeastern TibetDistinct crustal structures in the West Burma Block, southeastern Tibet, and the Shan Plateau coincide with distinct tectonic responsesTwo north‐south low‐velocity zones in mid‐to‐lower crust end near Red River Fault, indicating restricted crustal extrusion [ABSTRACT FROM AUTHOR]

To present an efficient method for fabricating artificial kidney stones with acoustic and physical properties to assess their fragmentation efficiency under shock waves and laser lithotripsy for very hard stones. The mixture ratio of super-hard plaster and water was adjusted to produce artificial kidney stones for comparison with > 95% human genuine calcium oxalate monohydrate (COM) and uric acid (UA) stones. Acoustic and physical properties, such as wave speed, stone hardness, density, compressive strength, and stone-free rates under shock-wave and laser lithotripsy, were assessed. The longitudinal wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 closely matched that of COM stones. Similarly, the transverse wave speed of artificial stones prepared at a plaster-to-water ratio of 15:3 to 15:5 aligned with that of COM stones. Stone fragmentation using shock-wave of artificial stones with mixed ratios ranging from 15:3 to 15:5 resembled that of COM stones. The Vickers hardness was similar to that of artificial stones produced with a mixing ratio of 15:3, similar to that of COM stones, while that of artificial stones produced with a mixing ratio of 15:5 was similar to that of UA stones. Density-wise, artificial stones with mixing ratios of 15:4 and 15:5 resembled COM stones. Compressive strength test results did not confirm the similarity between natural and artificial stones. The stone fragmentation using laser showed that stones produced with higher moisture content at a mixing ratio of 15:6 were similar to COM stones. This novel method for fabricating artificial kidney stones could be used to provide reliable materials for lithotripsy research. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to investigate whether prediction of liver fibrosis using two-dimensional shear wave elastography (2D-SWE) and vascular tree grading using superb microvascular imaging (SMI) are useful for postoperative follow-up in patients with biliary atresia (BA). Methods: We retrospectively collected data from medical records of 134 patients who underwent ultrasound examination with 2D-SWE or SMI, including 13 postoperative patients with BA and 121 non-BA patients. We investigated the distribution of liver stiffness values with SWE and vascular tree grading with SMI and evaluated correlations between these findings and biochemical indices of liver fibrosis in postoperative BA patients. Results: The SWE values of the BA group were not significantly different from that of any other disease groups in non-BA patients. In postoperative BA patients, SWE values correlated significantly with aspartate aminotransferase to platelet ratio index (Spearman rank correlation coefficient [rs] = 0.6380, p = 0.0256) and with the Fib-4 index (rs = 0.6526, p = 0.0214). SMI vascular tree grading of the BA group was significantly higher than that of the choledochal cyst group (p = 0.0008) and other hepatobiliary disorder group (p = 0.0030). In postoperative BA patients, SMI vascular tree grading was not positively correlated with any biochemical marker of fibrosis. Conclusion: 2D-SWE appears to be useful for follow-up in postoperative BA patients. [ABSTRACT FROM AUTHOR]

Mesenteric lymphadenitis (ML) demonstrates a distinctive inclination for the pediatric and adolescent demographic and the diagnosis of ML in young children poses a substantial challenge.This prospective study aimed to assess the diagnostic efficacy of Superb Microvascular Imaging (SMI) and Virtual Touch Tissue Imaging quantification (VTIQ) in distinguishing pediatric mesenteric lymphadentitis.We examined 82 mesentric lymph node (MLN) in pediatric patients with mesenteric lymphadentitis and 50 MLN in a healthy group. SMI was utilized to evaluate vascularity within the MLN, while MLN stiffness, quantified as shear wave velocity (SWV) in meters per second (m/s), was assessed using VTIQ. We compared the diagnostic performance of greyscale Ultrasound, US combined with SMI, US combined with VTIQ, and US combined with both SMI and VTIQ.SMI revealed a significant distinction between mesenteric lymphadentitis and normal MLN (p <  0.001). MLN affected by mesenteric lymphadentis exhibited increased vascularity (marked vascularity: 13/82, 15.85%) compared to normal MLN (marked vascularity: 1/50, 2.00%). Statistically significant differences were observed in SWV values beween mesenteric lymphadentitis and normal MLN (all p-values <0.001). The mean and minimum SWV values for MLN with mesenteric lymphadentitis were 1.66±0.77 m/s and 1.51±0.53 m/s, respectively. Control group SWV values were approximately three times higher than those in the mesenteric lymphadenitis group. The highest area under the curve values were achieved with the combination of all three modalities (0.837, 95% confidence interval: 0.763– 0.896), followed by US + VTIQ (0.795, 0.716– 0.860), US + SMI (0.753, 0.670– 0.824) and US alone (0.642, 0.554– 0.724).SMI and VTIQ offer a promising noninvasive adjunct to grayscale ultrasound for identifying mesenteric lymphadentitis in pediatric patients. [ABSTRACT FROM AUTHOR]

Ultrasound elastography has been available on most modern systems; however, the implementation of quality processes tends to be ad hoc. It is essential for a medical physicist to benchmark elastography measurements on each system and track them over time, especially after major software upgrades or repairs. This study aims to establish baseline data using phantoms and monitor them for quality assurance in elastography. In this paper, we utilized two phantoms: a set of cylinders, each with a composite material with varying Young's moduli, and an anthropomorphic abdominal phantom containing a liver modeled to represent early-stage fibrosis. These phantoms were imaged using three ultrasound manufacturers' elastography functions with either point or 2D elastography. The abdominal phantom was also imaged using magnetic resonance elastography (MRE) as it is recognized as the non-invasive gold standard for staging liver fibrosis. The scaling factor was determined based on the data acquired using MR and US elastography from the same vendor. The ultrasound elastography measurements showed inconsistency between different manufacturers, but within the same manufacturer, the measurements showed high repeatability. In conclusion, we have established baseline data for quality assurance procedures and specified the criteria for the acceptable range in liver fibrosis phantoms during routine testing. [ABSTRACT FROM AUTHOR]

The physics of shear waves traveling through matter carries fundamental insights into its structure, for instance, quantifying stiffness for disease characterization. However, the origin of shear wave attenuation in tissue is currently not properly understood. Attenuation is caused by two phenomena: absorption due to energy dissipation and scattering on structures such as vessels fundamentally tied to the material's microstructure. Here, we present a scattering theory in conjunction with magnetic resonance imaging, which enables the unraveling of a material's innate constitutive and scattering characteristics. By overcoming a three-order-of-magnitude scale difference between wavelength and average intervessel distance, we provide noninvasively a macroscopic measure of vascular architecture. The validity of the theory is demonstrated through simulations, phantoms, in vivo mice, and human experiments and compared against histology as gold standard. Our approach expands the field of imaging by using the dispersion properties of shear waves as macroscopic observable proxies for deciphering the underlying ultrastructures. [ABSTRACT FROM AUTHOR]

Background: The main cardiovascular risk factor related to higher likelihood of heart failure is hypertension [HTN]. There are plenty of researches on the pathological effects of HTN on the morphology and structure of the left ventricle [LV], but research investigating right ventricle [RV] mechanics in patients with hypertension have just recently emerged. So we aimed to assess whether blood pressure controlled or not had an impact on the systolic function of the RV. Methods: One hundred seventy two participants were assessed by 2D echocardiography for LV function m-mode, right ventricle RV including tissue doppler imaging[TDI] to evaluate RV myocardial performance index [MPI], RV s wave, tricuspid annular plane systolic excursion[TAPSE]. Speckle tracking study was done for global longitudinal strain [GLS] of LV RV and free wall strain. Results: Total of 172 participants were divided into, 86 were hypertensive in group I and 86 were normotensive in group II. TAPSE, MPI, RV s wave, PASP, LV-GLS, GLS of RV, and free wall strain were lower in group I. Subgroup analysis showed lower RVGLS in uncontrolled hypertensive patients. Conclusions: Uncontrolled hypertensive patients had lower RV-GLS in comparison to controlled hypertensive patients. The predictors of impaired RV GLS in uncontrolled BP patients were BMI, RV MPI, and LVGLS [ABSTRACT FROM AUTHOR]

Background: Endometrial and sub-endometrial lesions are a common cause of abnormal uterine bleeding. Ultrasound is a reliable diagnostic tool for those lesions, but not all patients exhibit definite changes in ultrasound, making additional techniques necessary. Elastography, such as shear wave elastography (SWE), can assess the mechanical properties of the endometrial lesions and provides a quantitative measure of tissue stiffness and so aids in differentiating different pathologies. Our study aimed to determine the added value of SWE in diagnosis of different endometrial and sub-endometrial lesions. Methods: Thirty-six female patients presented with abnormal uterine bleeding (AUB) with pathologically proven endometrial and sub-endometrial pathologies were included in this prospective study and assessed with transvaginal SWE. The mean elasticity values (E mean) in Kilopascals (KPa), and the ratio of the mean elasticity of the lesion to the mean myometrial elasticity (E/M ratio) were calculated in variable lesions. Results: There was a statistically significant difference in the E mean (P > 0.001) as well as the E/M ratio of different endometrial and sub-endometrial lesions (P > 0.001). E mean value in endometrial carcinoma (EC) was 39.79 ± 3.65, endometrial hyperplasia (EH) was 24.24 ± 1.52, and endometrial polyp was 15.74 ± 2.71. While that of submucosal fibroid was 59.36 ± 12.84 and adenomyoma (AM) was 52.15 ± 4.44. In the analysis of the subgroups, the E/M ratio of uterine polyp (0.36 ± 0.07) was statistically significantly lower than other subgroups (P >0.01), while submucosal leiomyoma (1.8 ± 0.27) and focal adenomyoma (1.37 ± 0.07) had significantly higher values than other subgroups (P < 0.01). Conclusions: Shear wave elastography is an effective additional method in differentiating between benign and malignant endometrial and sub-endometrial lesions when combined with conventional ultrasonography. [ABSTRACT FROM AUTHOR]

SUMMARY: Atmospheric pressure changes on Earth's surface can deform the solid Earth. Sorrells derived analytical formulae for displacement in a homogeneous, elastic half-space, generated by a moving surface pressure source with speed $c$. Ben-Menahem and Singh derived formulae when an atmospheric P wave impinges on Earth's surface. For a P wave with an incident angle close to the grazing angle, which essentially meant a slow apparent velocity $c_a$ in comparison to P- ($\alpha ^{\prime }$) and S-wave velocities ($\beta ^{\prime }$) in the Earth ($c_a \ll \beta ^{\prime } \lt \alpha ^{\prime }$), they showed that their formulae for solid-Earth deformations become identical with Sorrells' formulae if $c_a$ is replaced by $c$. But this agreement was only for the asymptotic cases ($c_a \ll \beta ^{\prime }$). The first point of this paper is that the agreement of the two solutions extends to non-asymptotic cases, or when $c_a /\beta ^{\prime }$ is not small. The second point is that the angle of incidence in Ben-Menahem and Singh's problem does not have to be the grazing angle. As long as the incident angle exceeds the critical angle of refraction from the P wave in the atmosphere to the S wave in the solid Earth, the formulae for Ben-Menahem and Singh's solution become identical to Sorrell's formulae. The third point is that this solution has two different domains depending on the speed $c$ (or $c_a$) on the surface. When $c/\beta ^{\prime }$ is small, deformations consist of the evanescent waves. When $c$ approaches Rayleigh-wave phase velocity, the driven oscillation in the solid Earth turns into a free oscillation due to resonance and dominates the wavefield. The non-asymptotic analytical solutions may be useful for the initial modelling of seismic deformations by fast-moving sources, such as those generated by shock waves from meteoroids and volcanic eruptions because the condition $c / \beta ^{\prime } \ll 1$ may be violated for such fast-moving sources. [ABSTRACT FROM AUTHOR]

SUMMARY: Greenland's tectonic history is complex, and the resulting lithospheric structure is, although extensively researched, not well constrained. In this study, we model the lithospheric structure of Greenland in a consistent, integrated framework with three steps. First, we build a lithospheric background model by forward modelling, adjusted to gravity gradient data and shear wave velocities from a regional tomography model. Subsequently, we jointly invert for the upper crustal density and susceptibility structure by minimizing the gravity residuals and magnetic total field anomaly misfit. The last modelling step searches for upper crustal thermal parameters to fit our model to the most recent geothermal heat flow predictions for Greenland. Finally, we present 3-D models of the density, temperature and velocity structure for the lithosphere as well as thermal parameters and susceptibilities for the upper crust. Our model also includes the depth of the Moho and LAB in Greenland. A comparison between inverted crustal parameters and surface geology shows a clear correlation. The novelty of our model is that all these results are consistent with each other and simultaneously explain a wide range of observed data. [ABSTRACT FROM AUTHOR]

SUMMARY: This study examines the topographic effect on the body-wave polarization and, subsequently, on near-surface wave speed estimation. We first derive 3-D P- and S-wave polarization angles in the presence of ground tilt, where the angles are functions of the ground tilt orientation, the near-surface wave speeds and the incident wave direction. We find that S-wave polarization angle varies considerably (e.g. more than 100 per cent) when the incident angle is close to the critical angle. The counter-intuitive phenomenon for flat surface, that is, P-wave polarization being only sensitive to S but not P wave speeds, breaks down in the presence of ground tilt, and P-wave polarization becomes sensitive to both P and S wave speeds. Examining the differences in the inferred wave speeds with and without the flat-surface assumption reveals that bias in wave speed estimates is, in general, higher for smaller incident angles, for example, about 50 per cent or higher for a 15° ground tilt and near-vertical (<5°) incidence. The effect on P wave speed estimates is also significant when the S-wave incident angle approaches the critical angle. In order to investigate the topographic effect on wave speed estimates inferred using teleseismic polarization data, we revisit the near-surface wave speed estimates at Hi-net stations from a previous study that did not account for the topography. Based on the ground tilt and strike angles measured for each Hi-net site at 300-m scale—which is found to be the most relevant scale—we constrain P and S wave speeds utilizing the P-wave polarization data. We find that P-wave polarization data alone can effectively constrain not only S but also P wave speeds, especially when the ground tilt is sufficiently large (e.g. >5°). Furthermore, our additional test suggests that including S-wave polarization data with the tilt consideration will improve the near-surface wave speed estimates significantly compared to when the tilt effect is ignored. [ABSTRACT FROM AUTHOR]

SUMMARY: Applications of machine learning in seismology have greatly improved our capability of detecting earthquakes in large seismic data archives. Most of these efforts have been focused on continental shallow earthquakes, but here we introduce an integrated deep-learning-based workflow to detect deep earthquakes recorded by a temporary array of ocean-bottom seismographs (OBSs) and land-based stations in the Tonga subduction zone. We develop a new phase picker, PhaseNet-TF, to detect and pick P- and S-wave arrivals in the time–frequency domain. The frequency-domain information is critical for analysing OBS data, particularly the horizontal components, because they are contaminated by signals of ocean-bottom currents and other noise sources in certain frequency bands. PhaseNet-TF shows a much better performance in picking S waves at OBSs and land stations compared to its predecessor PhaseNet. The predicted phases are associated using an improved Gaussian Mixture Model Associator GaMMA-1D and then relocated with a double-difference package teletomoDD. We further enhance the model performance with a semi-supervised learning approach by iteratively refining labelled data and retraining PhaseNet-TF. This approach effectively suppresses false picks and significantly improves the detection of small earthquakes. The new catalogue of Tonga deep earthquakes contains more than 10 times more events compared to the reference catalogue that was analysed manually. This deep-learning-enhanced catalogue reveals Tonga seismicity in unprecedented detail, and better defines the lateral extent of the double-seismic zone at intermediate depths and the location of four large deep-focus earthquakes relative to background seismicity. It also offers new potential for deciphering deep earthquake mechanisms, refining tomographic models, and understanding of subduction processes. [ABSTRACT FROM AUTHOR]

During the early Cenozoic, the collision and convergence between India and Eurasia resulted in the uplift of the Tibetan Plateau and continuous northward compression, forming the Circum‐Tibetan Plateau Basin and Orogen System (CTPBOS). The Tarim Basin, located between the Tibetan Plateau and the Tianshan Mountains, plays a crucial role for studying the convergence‐driving strain propagation mechanism intra‐Asian continent during the growth processes of the Tibetan Plateau. Owing to the lack of accurate geophysical information on the deep structure of the Tarim crust，the mechanism of Cenozoic deformation in the Tarim Basin has been under debate. In this paper, the teleseismic data acquired by the broadband seismic profile across the Tarim Basin from south to north and the S‐wave receiver function method were used to obtain the depth of the Moho and the discontinuities in the lithosphere beneath the Tarim Basin. The SRF result shows that the Moho geometry has an abrupt relief under the Bachu Uplift, and Moho offset under the fault zone between the Kalashayi Fault and the Tumuxiuke Fault. The regional dip of the Moho under the Bachu area can be explained by the root of the Bachu basement‐involved uplift cutting across the whole crust and locally penetrating into the mantle lithosphere. The Bachu Uplift, located in the central Tarim terrane, has a relatively weak lithosphere. In the process of forming the Tarim large igneous province during the early Permian, the crust beneath the Bachu area was weakened and thinned by the thermo‐mechanical erosion from upwelling mantle plume. As the collision and convergence of India and Eurasia since the early Cenozoic, the convergence‐driving strain was propagated into the Tarim Basin. The pre‐existing weak Bachu Uplift was reactivated. The Tarim Basin absorbs Cenozoic compressional deformation through the crustal shortening and Moho offset of the Bachu Uplift. [ABSTRACT FROM AUTHOR]

As the western boundary of the Sichuan-Yunnan block (SYB), the Red River fault (RRF) is a major fault that controls deep crustal movement and deformation in the southeast margin of the Tibetan Plateau and regulates middle-lower crustal flow. Geophysical data suggest that the RRF is segmented and exhibits distinct variations in seismicity, velocity structure and crustal deformation from north to south. Seismic anisotropy reveals a complex pattern of lateral spatial and vertical stratified distributions. (1) From the perspective of crustal stratification, in the upper crust, the fast wave polarization in the north segment of the RRF is complex and possibly influenced by the Sanjiang lateral collision zone and adjacent faults with varying strikes. The fast wave polarization in the middle segment is in the NW-SE direction, indicating a localized area of closed down or locked up with consistent deformation. And in the south segment, it presents a disordered pattern, signifying complex deep tectonics and stress conditions at the wedged intersection zone. In the middle-lower crust in the north and south segments of the RRF, the azimuthal anisotropy is strong and consistent with the spatial strike of the weak zone characterized by low-velocity and high-conductivity. This suggests a connection between the anisotropy and the material migration. (2) In the whole crustal scale, the fast wave directions in two sides of the RRF are consistent with the NW-SE tectonic strike. It indicates that the RRF, as a large fault potentially cutting through the whole crust, strongly controls the surrounding media. (3) In the lithospheric scale, the fast wave polarizations are oriented nearly E-W and independent of the fault strike, consistent with the low P- and S-wave velocity structures and positive radial anisotropy in the upper mantle. The fast wave directions could be related to lithospheric olivine deformation and asthenospheric flow. This paper suggests a decoupling of deformation between the crust and the lithospheric mantle in the south of approximately 26°20′N near the RRF, which can potentially be attributed to the subduction and rollback of the Indian plate. Based on various geophysical observations and inversions, we can determine the detailed anisotropic structure in the crust and the upper mantle around the RRF. Denser geophysical arrays and more accurate records can be used to explore the intricate anisotropy in segmentation and stratification around the RRF, enhancing the understanding of its tectonic significance. [ABSTRACT FROM AUTHOR]

The article contains the solution of a semi-infinite crack present at the interface of two dissimilar orthotropic strips sandwiched between dissimilar orthotropic strips. The crack is moving with a constant velocity, and the surface is under shear wave disturbance. Using the Fourier integral transform, the standard form for the Wiener–Hopf (W–H) equation is obtained for the proposed mathematical model, which is solved using the W–H method. The approximate analytic expressions for stress intensity factor, normalised stress intensity factor (NSIF) and the crack energy have been obtained for the considered crack problem. The behaviour of NSIF and normalised crack energy has been graphically presented for different crack propagation velocities and various ratios of depths of the strips of the composite material for different particular cases. The novelty of the article lies in finding the approximate analytic solutions of the proposed mathematical model using the W–H method, finding the expression for the length of the contact region near the crack tip and the pictorial presentations of the impact of exterior strips on the two dissimilar bonded strips containing the crack through finding the stress magnification factor. [ABSTRACT FROM AUTHOR]

The horizontal-to-vertical spectral ratio (HVSR) method has been used to characterize site-effect parameters that are indispensable in seismic hazard and risk-reduction studies in urban areas and rapid land-use planning. This method is widely used because it is the cheapest and simplest geophysical method for the acquisition and processing stages. In subsequent developments, the HVSR method has been widely used to determine elastic rock parameters, particularly shear wave velocity (vS), through the HVSR curve inversion process. Furthermore, the vS structural model can be used to delineate the presence of complex geological structures, particularly faults and sedimentary basins. Bandar Lampung is a city in Lampung Province with many fault structures and groundwater basins to the south. There are 83 HVSR measurement points around Bandar Lampung for delineating the presence of fault structures and groundwater basins. We produced the HVSR curve from the measurement results and then performed an inversion process using the particle swarm optimization algorithm to obtain vS for the depth profile. Subsequently, from this profile, we produced a two-dimensional (2D) lateral and vertical model. The mean vS value was calculated from all the measurement points, and we found stiff soil layers reaching depths of approximately 5 m, with a value of vS < 330 m/s. A bedrock layer with a velocity exceeding 1 250 m/s was visible at a depth of 100 m. Based on the 2D model, the vS structure shows that the city of Bandar Lampung is divided into two zones, with a NW-SE boundary. The north-middle-eastern part of the city consists of harder rocks. This harder rock is characterized by extremely high vS values, starting from a depth of 50 m. In contrast, the south-middle-west exhibits a low-moderate vS anomaly associated with groundwater basins SW of the city. From the 2D vS structural model, fault structures can be found along the city, characterized by a contrast of vS values from low to medium and from medium to high. [ABSTRACT FROM AUTHOR]

Microbial-induced calcium carbonate precipitation (MICP) is an emerging in situ grouting technology for sand ground improvement, slope stability, and subgrade reinforcement, featuring rapid implementation and low energy consumption. The precipitated calcium carbonate crystals can rapidly fill and cement sand particles so as to form a new soil structure that effectively reduces liquefaction sensitivity and dynamic damage. The centrifuge shake table test is an effective method for simulating liquefaction of sandy soil layers under shear wave excitation. Many studies have been conducted on this topic in recent years. However, the study on dynamic response, especially the liquefaction resistance of MICP-cemented sands by centrifuge shake table tests, is rare. In order to investigate the cementation effect of microbial treatment, centrifuge shake table tests were performed on two models, i.e., untreated and MICP cemented sand model. The test results indicated that, compared with untreated sand model, the liquefaction resistance of the MICP model was significantly improved in terms of acceleration response, shear stiffness, stress–strain relationship, and ground surface settlement. This study contributes to a better understanding of the mechanical law in the liquefaction process and enriches the engineering application of microbial grouting treatment of sand foundation prone to liquefaction. [ABSTRACT FROM AUTHOR]

Field-scale biocemented soil columns were installed in dry, poorly graded sand using enzyme-induced carbonate precipitation (EICP) and tube-à-manchette (TAM) permeation grouting. Column diameters ranged between 0.3 and 1.0 m, and column heights ranged from 1.0 to 2.4 m. Urease enzyme was obtained in the field from jack beans using tap water and a crude extraction process, with and without dehusking the beans. The biocementation treatment solution was injected in three cycles at approximately 24-h intervals. Test results showed that leaving the husks on the jack bean during extraction did not affect either injection or cementation. The plate load test showed an increase in bearing capacity by a factor of 3 and an increase in stiffness by a factor of 3 following treatment. Downhole seismic readings showed an increase in shear wave velocity of at least 100 m/s in the biocemented soil. Measurements on exhumed columns showed that the column dimensions were similar to the target dimensions. Needle penetrometer readings taken during exhumation indicated an unconfined compressive strength of at least 500 kPa. Carbonate content measurements on exhumed specimens varied from more than 4% (by weight) close to the TAM to less than 2% at the design radius, and an increased injection rate provided more uniform carbonate content. This field-scale program demonstrates that EICP can be employed using conventional grouting equipment and a simple enzyme extraction method to create biocemented columns with diameters of 0.3 to 1.0 m and a target strength of at least 500 kPa in 3 days. [ABSTRACT FROM AUTHOR]

This study utilized real-time shear wave elasticity imaging (SWE) and ultrafast pulse wave velocity (ufPWV) to assess carotid arterial stiffness, aiming to predict atherosclerosis risk in patients with metabolic syndrome (MS). In this study, 181 patients with metabolic syndrome (MS group) were compared with 73 healthy adults. The MS group was divided into three groups: MS I group: CIMT was normal (CIMT < 1.0 mm, no plaque, n = 61); MS II group: CIMT thickening (1.0 mm ≤ CIMT<1.5 mm, no plaque, n = 39); MS III group: plaque group (CIMT ≥ 1.5 mm, plaque, n = 81). Concurrently, the group of 73 healthy individuals was designated as the control set (NC). Parameters assessed include carotid intima-media thickness (CIMT), elastic modulus values of the carotid artery's anterior and posterior walls (Mean, Max, Min), pulse wave velocity at systole's commencement (PWV-BS), and pulse wave velocity at systole's termination (PWV-ES). Differences, distribution characteristics, and correlations across these groups were analyzed. A significant association was found between PWV-BS, PWV-ES, and arteriosclerosis severity, with these factors gaining importance as arteriosclerosis progressed. Notably, PWV-ES differences were significant across the four groups (p < 0.05). Both MS III and MS II groups exhibited higher PWV-ES values compared to the MS I group and controls. Statistically significant differences were observed between MS III, MS II, and MS I groups relative to the control group (p < 0.05). Additionally, the Mean, Max, and Min values of the anterior and posterior carotid walls in the MS III group surpassed those of the other groups. Real-time shear wave elasticity imaging and ultrafast pulse wave velocity are valuable tools for assessing atherosclerosis risk in MS patients. These non-invasive, safe, and reproducible imaging techniques can quantitatively evaluate the stiffness of the common carotid artery's wall, offering important insights into cardiovascular risk assessment. [ABSTRACT FROM AUTHOR]

A new liquefaction probability model based on shear wave velocity (Vs) was developed through a detailed comparative analysis of existing evaluation methods. Publicly available shear wave velocity liquefaction data were used to evaluate multiple existing liquefaction probability assessment methods under various probability contours and fines content levels. Significant performance differences were observed among the formulae under varying fines content levels. To construct the new model, the random forest feature importance ranking algorithm was employed to select the key parameters, including the effective stress-normalized shear wave velocity (Vs1), corrected cyclic resistance ratio (CSR7.5), magnitude (MW), depth (Z), and fines content (FC). Using these parameters, a new liquefaction probability assessment formula was developed utilizing the logistic regression model to predict the liquefaction probability. The new formula's performance was subsequently evaluated through a detailed case analysis and validation. The results demonstrate that the new formula achieves a higher accuracy (3–11%) for the liquefaction assessment compared to the existing formulae, performing consistently well across different probability contours and fines content levels, especially in areas with high fines content. This study provides theoretical support and empirical evidence for optimizing the shear wave velocity-based liquefaction probability assessment methods. [ABSTRACT FROM AUTHOR]

Background: Sjögren's syndrome (SS) is a common rheumatic disease for which finding the right imaging tool remains a challenge. Purpose: This study aimed to evaluate the performance of salivary gland ultrasonography (SGUS), shear wave elastography (SWE) and their combined use for the diagnosis of primary and secondary SS (pSS and sSS). Methods: This retrospective study included patients with dry symptoms who underwent routine examinations between May 2019 and December 2023. Patients were categorized into the pSS (n = 41), sSS (n = 26), and control (n = 27) groups based on the American College of Rheumatology/European League Against Rheumatism classification criteria (2016). A comparison of SGUS and shear wave velocity (SWV) results was conducted among the three groups. The diagnostic capabilities of different ultrasound methods for SS were evaluated using receiver operating characteristic (ROC) curves and the area under the curve (AUC) for specificity. Results: Compared to the control group, both the pSS (1.80 ± 1.03 vs. 0.67 ± 0.48, p < 0.001) and the sSS (1.85 ± 0.88 vs. 0.67 ± 0.48, p < 0.001) groups exhibited significantly elevated SGUS scores. However, there was no statistically significant difference between the pSS and sSS groups (p = 0.849). The SWV values in both the pSS and sSS groups were significantly higher than those in the control group (all p < 0.001). The AUC for diagnosing SS using only SGUS scores was 0.823 (95% confidence interval [CI]: 0.731–0.894). Combining SGUS scores and SWV values resulted in improved diagnostic accuracy (AUC: 0.883, 95% CI: 0.801–0.940). Conclusions: SGUS and SWE are pivotal in the diagnosis of Sjögren's syndrome, with their synergistic application poised to bolster diagnostic precision. This combined approach also furnishes substantial backing for the clinical assessment and management of Sjögren's syndrome. [ABSTRACT FROM AUTHOR]

In this article, the proposed model analyzed shear wave propagation through an orthotropic strip with an edge crack. Dual integral equations have been developed for solution of the governing mixed boundary value problem with the aid of Hankel transform technique. Then, the dual integral equations have been transformed into a second kind Fredholm integral equation employing Abel's transformation. The numerical calculations of stress intensity factor and crack opening displacement are performed utilizing the Fox & Goodwin method and displayed graphically. Elastic constants of two orthotropic materials have been used to illustrate the influence of material orthotropy and normalized strip width on SIF and COD. [ABSTRACT FROM AUTHOR]

Partial replacement of conventional stabilizers with environmentally-friendly and sustainable materials has recently turned out to be a common approach to enhance the strength and stiffness properties of earthen materials. In this regard, natural zeolite and expanded polystyrene (EPS) beads are used in this study to be added to clay samples conventionally stabilized with lime. Accordingly, a systematic survey is conducted to inspect the changes in mechanical strength and shear stiffness of untreated and lime-zeolite treated reconstituted clays (with various proportions of kaolinite and montmorillonite) due to the incorporation of EPS beads. To this end, first, the optimum percentage of lime was obtained from a series of pH tests. Then, the optimum content of lime replacement with zeolite yielding the highest unconfined compressive strength (UCS) was estimated which appeared to be 25%. Afterward, all the samples were lightened by adding 0.1% and 0.25% weight ratios of EPS beads to the fine materials (η ) and the results were compared with similar samples without EPS beads. Several standard Proctor compaction, swelling, UCS, and non-destructive bender element (BE) tests were carried out on lightened samples to assess their physical properties, strength characteristics, shear wave velocity ( V s ) and small-strain shear modulus ( G max ). The samples' swelling and compaction properties decreased by incorporating the EPS beads. Strength and stiffness characteristics of lightened composites were observed to be acceptable when 0.1 % EPS beads (denoted as the optimum percentage) were included in the studied mixtures. Furthermore, to interpret microscale phenomena, scanning electron microscopy (SEM) micrographs of the interfaces of the typical untreated and treated samples are provided, which demonstrate the interlocking zones, formation of cementitious gels and the considerable volume of the clay medium occupied by deformable EPS beads leading to the significant reduction in the soil weight. Finally, using the group method of data handling (GMDH)-type neural network (NN), several statistical modelings are carried out to predict the UCS, V s , and G max of the studied mix designs, which resulted in highly accurate models. [ABSTRACT FROM AUTHOR]

A numerical simulation of the detonation propagation process of acetylene-air under fuel-rich conditions is carried out using a reduced acetylene reaction model. The loose coupling method is used to solve the conservation equations with source terms. The flow is solved explicitly using a gas kinetic scheme, and the chemical reactions are solved implicitly. The numerical results show that the oxidation reaction is the chain initiation in the self-sustained detonation propagation process in rich acetylene. The self-decomposition reaction of acetylene provides the energy to maintain the coupling between the shock wave and the chemical reaction zone. The results show that the initial induced reaction is still an oxidation reaction due to the low activation energy of the oxidation reaction under the condition of low oxygen content. The intensity of the transverse wave is affected by the acetylene concentration. The post-detonation disturbance of temperature is mainly affected by the strength of the tail of transverse wave and the area of the unreacted pocket. With the increase of acetylene concentration, the self-decomposition process of acetylene increases the intensity of the transverse wave tail and improves the degree of temperature homogenization. This creates a formation-fragmentation-regeneration cycle of polycyclic aromatic hydrocarbons. This process changed the branching ratio of polycyclic aromatic hydrocarbons with different structures and delayed the formation of polycyclic aromatic hydrocarbons. When the acetylene concentration is low, the region where the dominant temperature after detonation is 1500 ~ 2500 K provides a favorable environment for the growth of polycyclic aromatic hydrocarbons. [ABSTRACT FROM AUTHOR]

This article presents an extensive analytical solution addressing the interaction between two non‐identical edge cracks in an infinite orthotropic strip under anti‐plane shear waves. Most studies assume identical cracks or single edge crack in a strip, but this research breaks new ground by considering cracks of different sizes. By incorporating mixed‐type boundary conditions, the study derives dual integral equations. These equations are then transformed into a singular integral equation of Cauchy type with the aid of a trial solution and contour integration technique. The singular integral equation is further converted into a system of integral equations, which are solved numerically utilizing Jacobi polynomials. The obtained solutions are utilized to derive expressions for the stress intensity factor (SIF) and crack opening displacement (COD) at the crack tip using Krenk's interpolation formulae. The derived results are presented graphically and compared against existing solutions for single edge crack and symmetric edge cracks in static scenario. [ABSTRACT FROM AUTHOR]

Renal anisotropy is a complex property of the kidney and often poses a challenge in obtaining consistent measurements when using shear wave elastography to detect chronic kidney disease. To circumvent the challenge posed by renal anisotropy in clinical settings, a dimensionless biomarker termed the ‘anisotropic ratio’ was introduced to establish a correlation between changes in degree of renal anisotropy and progression of chronic kidney disease through an in silico perspective. To achieve this, an efficient model reduction approach was developed to model the anisotropic property of kidneys. Good agreement between the numerical and experimental data were obtained, as percentage errors of less than 5.5% were reported when compared against experimental phantom measurement from the literature. To demonstrate the applicability of the model to clinical measurements, the anisotropic ratio of sheep kidneys was quantified, with both numerical and derived experimental results reporting a value of .667. Analysis of the anisotropic ratio with progression of chronic kidney disease demonstrated that patients with normal kidneys would have a lower anisotropic ratio of .872 as opposed to patients suffering from renal impairment, in which the anisotropic ratio may increase to .904, as determined from this study. The findings demonstrate the potential of the anisotropic ratio in improving the detection of chronic kidney disease using shear wave elastography. [ABSTRACT FROM AUTHOR]

As a common defect, the water–cement ratio of grout can currently be monitored only during the maintenance phase, which limits the repair methods and misses the optimal opportunity for repairs. To overcome this limitation, this study integrated ultrasonic parameters previously used to characterise cement-based materials and developed a new Initial Setting Time and Water–Cement Ratio (IST_WCR) risk model to predict the setting time and water–cement ratio grout using machine learning (ML) algorithms. Experiments on grout involved four different water–cement ratios, ranging from 0.11 to 0.18. A data-driven method based on ML was used to extract predictive factors from eight ultrasonic parameters, including the speed, energy, main frequency, and main frequency amplitude of P-waves and S-waves, and to evaluate multiple ML classifiers to establish the IST_WCR risk prediction model. This model underwent internal and external cross-validations and demonstrated very strong performance with a Brier score of under 0.01. The dataset for ML classifiers contained a total of 956 signals and 7648 features. Compared with traditional methods, this method can automatically characterise the setting process of grout and identify defective water–cement ratios at a very early stage of curing. [ABSTRACT FROM AUTHOR]

One‐dimensional site response analysis (1D SRA) remains the standard practice in considering the effect of local soil deposits and predicting site‐specific ground motions, although its range of applicability to realistic seismic wavefields is still in question. In this 1D approach, horizontal and vertical ground shaking are assumed to be induced by vertically propagating shear and compressional waves, respectively. A recent study based on analytical two‐dimensional (2D) plane waves and simple point source earthquake simulations has shown two mechanistic limitations in this 1D modelling technique for general inclined seismic waves, that is, systematic over‐prediction of the vertical motion and wave trapping in the 1D soil column. In this article, we evaluate in detail the applicability of this 1D modelling approach to realistic three‐dimensional (3D) simulated seismic wavefields in shallow sedimentary basins. Linear‐viscoelastic 1D SRA predictions using two types of input motions that are commonly used in practice—rock outcrop and in‐column motions, are compared with the reference true site response results from 3D earthquake simulations in terms of various measures in the frequency and time domain. It is shown that the horizontal motion in the 3D seismic wavefield exhibits dominant shear wave propagation phenomenon, while the vertical motion is a combined effect of compressional and shear waves and can be over‐predicted by the 1D approach when the incident seismic waves are inclined. Direct evidence of the wave refraction process that leads to the vertical motion over‐prediction is provided. 1D SRA with in‐column inputs can yield motions that have significantly longer duration compared to the true 3D site response solution due to trapped waves, casting in doubt the frequent need for increased soil damping in existing site studies to compensate for wave attenuation due to scattering alone. Sensitivity investigation on the increase of soil profile damping by a multiplier Dmul shows Dmul values compatible with those found in the literature for both horizontal and vertical motions. It is shown that the level of Dmul optimized for a best match of the spectral acceleration is dependent on the characteristic of the input motion and a larger Dmul is typically required for the vertical component. In contrast, 1D SRA with outcrop motions predicts motions with shorter significant duration due to its inability to capture the basin‐edge generated surface waves. A suite of ground motion simulations was performed to assess the sensitivity of the observations to the basin geologic structure including the velocity gradient, rock‐basin impedance contrast and basin depth. The analysis results show that the accuracy of the simplified 1D procedure is dependent on the wavefield composition of both the input motions and the true 3D site response solution. While the horizontal motions in shallow sedimentary basins can, to the first order, be reasonably captured by the simplified 1D approach, 1D SRA for the vertical component is in general not reliable and contributions from inclined shear waves should be accounted for in site‐specific evaluation of the vertical design ground motion. [ABSTRACT FROM AUTHOR]

Patellar tendon (PT) complaints are frequent in competitive alpine skiers and such complaints are characterized by a long-lasting affection. Since PTs are subject to maturation up to 1-2 years after growth spurt, this early career stage may be decisive for the further course of complaints. The aim of this study was to investigate the evolution of PT complaints and shear wave velocity patterns among competitive alpine skiers during a 4-year post-growth spurt follow-up. The PT complaints and SWV patterns of forty-seven skiers were analysed at baseline (i.e., immediately after their peak height growth at 13-15 years of age) and were re-analysed at 4-year follow-up. The PTs were scanned via threedimensional SWE. Symptomatic skiers were identified based on pain sensation under loading and pressure-induced pain around the PT. The prevalence of PT complaints decreased from 29.8% at baseline to 12.8% at follow-up (Pearson's 2 = 9.429; p = 0.002). SWV decreased from the baseline assessment to the follow-up in the proximal and distal regions (p < 0.05). SWV coefficient of variation (CV) in the distal and mid-portion regions was greater at baseline than at follow-up (p < 0.05). At the follow-up assessment, compared to "healthy" skiers, "healed" skiers who recovered from PT complaints had lower SWVs in the proximal region (p = 0.020) and greater SWV CVs in the proximal region (p = 0.028). Moreover, symptomatic skiers had significantly greater SWV CVs in the mid-portion region than did "healthy" subjects with no history of PT complaints (p = 0.020). The average SWV was negatively correlated with the SWV (proximal: r = -0.74, p < 0.001; mid-portion: r = -0.37 p = 0.011; and distal: r = -0.58, p < 0.001). The occurrence of PT complaints decreased over a 4-year post-growth spurt follow-up. "Healed" skiers who were symptomatic at baseline had an even greater average decrease in the proximal and mid-portion SWV than "healthy" skiers with no history of PT complaints. This may lead to the hypothesis that PT complaints in adolescent skiers are not self-eliminating towards the end of adolescence, as at least structural irregularities appear to persist for several years after the onset of initial symptoms. Furthermore, "healed" and symptomatic tendons exhibited increased SWV variability, supporting the hypothesis that SWV CV may provide additional valuable information on the mechanical properties of PTs affected by overuse-related complaints. [ABSTRACT FROM AUTHOR]

Dynamic deformation events induced by osmosis or photochemical stiffening substantially influence geometrical and mechanical assessments in post-mortem corneas, therefore need to be carefully monitored in experimental settings. In this study, we employed optical coherence elastography (OCE) to quantify dynamic deformation processes at high resolution in freshly enucleated porcine corneas. Osmotic effects were studied by immerging n = 9 eyes in preservation media of three different tonicities. Dynamic processes underlying corneal cross-linking (CXL) were studied by subjecting n = 6 eyes to standard Dresden treatment, while three control groups were used. The entire procedures were performed under an OCE setup during up to 80 min, acquiring a volumetric scan every 20 s. Changes in OCE-derived axial deformations were incrementally calculated between consecutive scans. Preservation conditions had a strong influence on the observed strain patterns, which were consistent with the tonicity of the medium (swelling in hypotonic, deswelling in hypertonic environment). In the CXL group, we observed deswelling of the anterior stroma 10 min after starting the UV irradiation, which was not observed in any control group (p = 0.007). The presented results proved OCE to be a valuable technique to quantify subtle dynamic biomechanical alterations in the cornea resulting from CXL and preservation solutions. [ABSTRACT FROM AUTHOR]

The Universe expansion rate is modulated around local inhomogeneities due to their gravitational potential. Velocity waves are then observed around galaxy clusters in the Hubble diagram. This paper studies them in a ∼738 Mpc-wide, 20483-particle cosmological simulation of our cosmic environment (a.k.a. CLONE: Constrained LOcal & Nesting Environment Simulation). For the first time, the simulation shows that velocity waves that arise in the lines of sight of the most massive dark matter halos agree with those observed in local galaxy velocity catalogs in the lines of sight of Coma and several other local (Abell) clusters. For the best-constrained clusters such as Virgo and Centaurus – that is, those closest to us – secondary waves caused by galaxy groups, further into the non-linear regime, also stand out. This match was not utterly expected given that before being evolved into a fully non-linear z = 0 state, assuming ΛCDM, CLONE initial conditions are constrained solely with linear theory, the power spectrum, and highly uncertain and sparse local peculiar velocities. Additionally, Gaussian fits to velocity wave envelopes show that wave properties are tightly tangled with cluster masses. This link is complex, though, and involves the environment and formation history of the clusters. A proposed metric, measuring the distance between the observed and several re-centred simulated lines of sight, waves included, is shown to be capable of providing a tight mass range estimate for massive local clusters. Using machine learning techniques to grasp more thoroughly the complex wave-mass relation, velocity waves could in the near future be used to provide additional and independent mass estimates from galaxy dynamics within large cluster radii. [ABSTRACT FROM AUTHOR]

Background: Transient Elastography (TE) is widely regarded as the most reliable non-invasive method for evaluating liver fibrosis. Recently, new techniques such as 2D Shear Wave Elastography (2D-SWE) have been developed. This study aimed to evaluate the correlation between TE and 2D-SWE in patients with HCV-related chronic liver disease and to redefine the cut-off values of 2D-SWE for predicting different stages of fibrosis based on our results. Methods: Both TE (Fibroscan, Echosens, Paris, France) and 2D-SWE (SuperSonic Imagine) were performed simultaneously in 170 patients, including those with active and eradicated HCV infection. Spearman's rank correlation coefficient was used to assess the correlation between the two measurements, and the concordance between the assigned METAVIR classes was calculated using Cohen's kappa coefficient. ROC curves were constructed to determine the optimal cut-off values for 2D-SWE. Results: Ten patients were excluded for invalid measurements. In the remaining 160 patients, TE and 2D-SWE demonstrated a high correlation (ρ = 0.83, p < 0.0001) and good agreement in METAVIR classification (k = 0.74). The optimal cut-off values identified for 2D-SWE were as follows: ≥ 7 kPa for F ≥ 2, ≥ 8.3 kPa for F ≥ 3, and ≥ 9.4 kPa for F4. Conclusions: 2D-SWE is a viable alternative to TE for patients with HCV-related chronic liver disease. Our data suggest that the currently accepted 2D-SWE cut-off values for cirrhosis (F4) should be reconsidered and potentially lowered. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to clarify the relationship between fluctuations in uterine stiffness during the third stage of labor and blood loss upon placenta delivery using shear wave elastography. Methods: This prospective cohort study enrolled consecutive singleton pregnant women above 37 weeks of gestation who delivered infants transvaginally at a single perinatal center. Shear wave velocities (SWV) were continuously measured during the third stage of transvaginal labor using transabdominal ultrasound and these values were compared between groups with large (≥500 g) and small amounts of bleeding during this stage. Results: In total, 8 cases of large bleeding and 47 cases of small bleeding were compared. The large amount of bleeding group had a significantly lower median of minimum SWV values (0.97 [0.52–1.01] m/s than the small amount of bleeding group (1.25 [1.04–1.48] m/s p = 0.02). However, no significant differences were observed between the two groups in terms of median, mean, and maximum SWV values. The time from delivery of the infant to placental delivery was significantly longer in the large amount of bleeding group (median time: 370.5 s vs. 274 s, p < 0.05). Conclusion: Ultrasound quantification of uterine stiffness using shear wave elastography demonstrated that uterine contractions may influence the biological hemostasis of the uterus during the third stage of labor. Baseline uterine stiffness was weak and a longer duration of placental separation might be associated with cases of large amounts of bleeding during this stage. [ABSTRACT FROM AUTHOR]

Plantar fasciopathy is a very common musculoskeletal complaint that leads to reduced physical activity and undermines the quality of life of patients. It is associated with changes in plantar fascia structure and biomechanics which are most often observed between the tissue's middle portion and the calcaneal insertion. Sonographic measurements of thickness and shear wave (SW) elastography are useful tools for detecting such changes and guide clinical decision making. However, their accuracy can be compromised by variability in the tissue's loading history. This study investigates the effect of loading history on plantar fascia measurements to conclude whether mitigation measures are needed for more accurate diagnosis. The plantar fasciae of 29 healthy participants were imaged at baseline and after different clinically relevant loading scenarios. The average (±standard deviation) SW velocity was 6.5 m/s (±1.5 m/s) and it significantly increased with loading. Indicatively, five minutes walking increased SW velocity by 14% (95% CI: −1.192, −0.298, t(27), p = 0.005). Thickness between the calcaneal insertion and the middle of the plantar fascia did not change with the tissues' loading history. These findings suggest that preconditioning protocols are crucial for accurate SW elastography assessments of plantar fasciae and have wider implications for the diagnosis and management of plantar fasciopathy. [ABSTRACT FROM AUTHOR]

The influence of acoustic anisotropy on ultrasonic testing reliability poses a challenge in evaluating products from additive technologies (AT). This study investigates how elasticity constants of anisotropic materials affect defect signal amplitudes in AT products. Experimental measurements on AT samples were conducted to determine elasticity constants. Using Computational Modeling and Simulation Software (CIVA), simulations explored echo signal changes across ultrasound propagation directions. The parameters A 13 (the ratio between the velocities of ultrasonic transverse waves with vertical and horizontal polarizations at a 45-degree angle to the growth direction), A 3 (the ratio for waves at a 90-degree angle), and A g (the modulus of the difference between A 13 and A 3 ) were derived from wave velocity relationships and used to characterize acoustic anisotropy. Comparative analysis revealed a strong correlation (0.97) between the proposed anisotropy coefficient A g and the amplitude changes. Threshold values of A g were introduced to classify anisotropic materials based on observed amplitude changes in defect echo signals. In addition, a method leveraging deep learning to predict A g based on data from other anisotropy constants through genetic algorithm (GA)-optimized neural network (NN) architectures is proposed, offering an approach that can reduce the computational costs associated with calculating such constants. [ABSTRACT FROM AUTHOR]

In this work, we present a novel preclinical device utilizing Torsional Wave Elastography (TWE). It comprises a rotational actuator element and a piezoceramic receiver ring circumferentially aligned. Both allow the transmission of shear waves that interact with the tissue before being received. Our main objective is to demonstrate and characterize the reliability, robustness, and accuracy of the device for characterizing the stiffness of elastic materials and soft tissues. Experimental tests are performed using two sets of tissue mimicking phantoms. The first set consists of calibrated CIRS gels with known stiffness value, while the second test uses non-calibrated manufactured phantoms. Our experimental observations show that the proposed device consistently and repeatably quantifies the stiffness of elastic materials with high accuracy. Furthermore, comparison with established techniques demonstrates a very high correlation (> 95%), supporting the potential medical application of this technology. The results obtained pave the way for a cross-sectional study aiming to investigate the correlation between gestational age and cervical elastic properties during pregnancy. [ABSTRACT FROM AUTHOR]

The firn layer covers 98% of Antarctica's ice sheets, protecting underlying glacial ice from the external environment. Accurate measurement of firn properties is essential for assessing cryosphere mass balance and climate change impacts. Characterizing firn structure through core sampling is expensive and logistically challenging. Seismic surveys, which translate seismic velocities into firn densities, offer an efficient alternative. This study employs Distributed Acoustic Sensing technology to transform an existing fiber‐optic cable near the South Pole into a multichannel, low‐maintenance, continuously interrogated seismic array. The data resolve 16 seismic wave propagation modes at frequencies up to 100 Hz that constrain P and S wave velocities as functions of depth. Using co‐located geophones for ambient noise interferometry, we resolve very weak radial anisotropy. Leveraging nearby SPICEcore firn density data, we find prior empirical density‐velocity relationships underestimate firn air content by over 15%. We present a new empirical relationship for the South Pole region. Plain Language Summary: Firn, the layer of compacted snow merging into glacial ice covering Antarctica, acts as an insulating blanket that mitigates environmental perturbations to the polar ice sheet. Understanding the density and seismic characteristics of the firn layer helps scientists better infer its properties and variation, including factors relevant to glacial stability and sea level change. Firn density is the major uncertainty source for measuring ice sheet mass changes via satellite and airborne sensing. Traditional methods of assessing firn density involve drilling or snow pit analyses and are expensive and time‐consuming. We utilize the rapidly developing technology of Distributed Acoustic Sensing to transform a data communication cable near the South Pole into a dense array of seismic sensors, allowing us to noninvasively estimate firn properties by studying seismic waves propagating in the firn to assess its physical properties. Our findings suggest that previous parameterizations overestimate firn density by over 5% and underestimate its air content by over 15% and highlight the value of seismology for advancing glaciological and polar region's climate research. Key Points: Distributed Acoustic Sensing repurposes an 8 km fiber‐optic cable at the South Pole into a dense seismic arrayGathered data resolve 16 dispersion modes at frequencies up to 100 Hz that constrain P‐ and S‐wave velocities in the firn layerPrevious density‐velocity empirical relations overestimate the dry firn density at South Pole [ABSTRACT FROM AUTHOR]

Background: This study aims to investigate the role of shear wave elastography (SWE) and connective tissue growth factor (CTGF) in the assessment of papillary thyroid carcinoma (PTC) prognosis. Methods: CTGF expression was detected with immunohistochemistry. Clinical and pathological data were collected. Parameters of conventional ultrasound combined with SWE were also collected. The relationship among CTGF expression, ultrasound indicators, the elastic modulus and the clinicopathological parameters were analyzed. Results: Univariate analysis showed that patients with high risk of PTC were characterized with male, Uygur ethnicity, increased expression of CTGF, convex lesions, calcified, incomplete capsule, intranodular blood flow, rear echo attenuation, cervical lymph node metastasis, lesions larger than 1 cm, psammoma bodies, advanced clinical stage, increased TSH and high value in the shear modulus (P < 0.05). Multivariate analysis demonstrated that the risk factors of high expression of CTGF according to contribution size order were irregular shape, aspect ratio ≥ 1, and increased TSH. The logistic regression model equation was Logit (P) = 1.153 + 1.055 × 1 + 0.926 × 2 + 1.190 × 3 and the Area Under Curve value of the logistic regression was calculated to be 0.850, with a 95% confidence interval of 0.817 to 0.883. Conclusion: SWE and CTGF are of great value in the risk assessment of PTC. The degree of fibrosis of PTC is closely related to the prognosis. The hardness of PTC lesions and the expression level of CTGF are correlated with the main indexes of conventional ultrasound differentiating benign or malignant nodules. Irregular shape, aspect ratio ≥ 1, and increased TSH are independent factors of CTGF. [ABSTRACT FROM AUTHOR]

Active hotspot volcanism is the surface expression of ongoing dynamic subsurface changes, such as the generation, transport, and stalling of magmas within the upper mantle and crust. Magmatic influx and migration affects local stress patterns in the crust and lithospheric mantle, which influences seismic anisotropy. A better understanding of those patterns helps improve robustness of models forecasting the likelihood of an eruption and prolonged seismicity, with detailed studies being required to observe the significant variations that can occur on small spatial and temporal scales. Here, we investigate seismic anisotropy before, during and after volcanic eruptions. We use local seismicity around El Hierro and La Palma, the two westernmost islands in the Canaries and sites of the most recent volcanic eruptions in the archipelago. We obtained 215 results in El Hierro during and after the 2011/2012 eruption with five three-component broadband seismic stations and 908 results around the 2021 eruption in La Palma with two three-component broadband stations. On La Palma, the majority of seismicity and splitting results are recorded during the eruption and simultaneous deflation of the island. Seismicity locations do not change significantly and fast shear wave polarisation direction is mostly constant, but some variation can be attributed to changes in the magmatic plumbing system. On El Hierro, the general radial pattern reflects stresses induced by the overall uplift of the island during multiple magma intrusion events. Temporal subsets reveal significant variations in location and depth of the events, as well as significant variations in fast polarisation direction caused by ongoing dynamic changes of under- and overpressurisation. An increase of results starting in 2018 hints towards renewed subsurface activity within deeper parts of the plumbing system, affecting the rate of overall seismicity but not any vertical movement of the island. [ABSTRACT FROM AUTHOR]

A CF/PEEK‐reinforced Al metal‐composite hybrid structure (CF/PEEK/Al) and CF/PEEK bar were subjected to high strain rate compression tests with a split Hopkinson pressure bar (SHPB). With the increase in strain rates, both CF/PEEK and CF/PEEK/Al showed the strain rate strengthening effect, and the microscopic fracture surface of CF/PEEK changes from rough to smooth. In the plastic rheological stage of stress–strain curve, CF/PEEK shows a plateau effect, while CF/PEEK/Al shows the strain weakening effect. When the strain rate exceeds 3800 s−1, the stress–strain curve exhibits a secondary wave peak. The peak values of the secondary peak in CF/PEEK/Al are larger than CF/PEEK. In terms of peak stress, yield stress, and specific energy absorption, CF/PEEK/Al outperforms CF/PEEK. Compared with other structures, the CF/PEEK/Al metal‐composite hybrid structure has certain advantages in terms of yield strength and yield strain. The finite element method (FEM) and DIC system were applied to observe the dynamic damage process in the compression impact test. It was found that in CF/PEEK/A1, the Al thin‐walled tube was damaged and cracked at the contact interface, and the inner CF/PEEK began to be damaged at the contact center with the input bar. And at 335 μs after contact began, the shear band ran through to the side of the samples. Highlights: A CF/PEEK‐reinforced Al metal‐composite hybrid structure (CF/PEEK/Al) was proposed, which is superior to CF/PEEK.When the strain rate exceeds 3800 s−1, the stress–strain curves of CF/PEEK and CF/PEEK/Al exhibit a secondary wave peak. The peak values of the secondary peak in CF/PEEK/Al are larger than CF/PEEK.With the increase in strain rates, both CF/PEEK and CF/PEEK/Al showed the strain rate strengthening effect, and the microscopic fracture surface of CF/PEEK changes from rough to smooth.In CF/PEEK/A1, the Al thin‐walled tube was damaged and cracked at the contact interface, and the inner CF/PEEK began to be damaged at the contact center with the input bar. And at 335 μs after contact began, the shear band ran through to the side of the samples. [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]

Deep vein thrombosis (DVT) of the lower limbs is a venous reflux disorder caused by abnormal coagulation of blood components, primarily characterised by swelling and pain in the lower limbs. Key risk factors include prolonged immobility due to bed rest, pregnancy, postpartum or postoperative states, traumas, malignant tumours and long-term contraceptive use. To investigate the application of real-time shear wave elastography (SWE) in diagnosing lower-limb deep vein thrombosis (DVT). A total of 91 patients with DVT were selected and divided into three groups: acute phase (n= 29), subacute phase (n= 30) and chronic phase (n= 32). The Young’s modulus of the patients was measured using real-time SWE. The diagnostic efficacy of Young’s modulus was evaluated by ROC curves. The hardness differences in Young’s modulus across different parts of the same thrombus (head, body and tail) were measured using SWE. Before treatment, significant differences were observed in Young’s modulus among patients with DVT (P< 0.001). Following anticoagulant therapy, catheter-directed thrombolysis and systemic thrombolysis, significant differences were noted in Young’s modulus among patients at the same stage but receiving different treatments (acute phase: P= 0.003; subacute phase: P= 0.014; chronic phase: P= 0.004). Catheter-directed thrombolysis had greater efficacy than anticoagulant therapy. The area under the curve for SWE in staging patients was 0.917, with a sensitivity of 92.36% and specificity of 93.81%. Significant differences in Young’s modulus were found between the thrombus head and thrombus body and tail but not between the thrombus body and thrombus tail. Measurement of Young’s modulus using SWE can serve as an auxiliary means of evaluating staging, predicting pulmonary embolism and selecting treatment in patients with DVT. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To evaluate pancreatic tissue stiffness and provide a normal reference shear wave velocity (SWV) value of pancreas from healthy adults by Virtual Touch Imaging Quantification (VTIQ) measurements. METHODS: Healthy adult volunteers without known history of hepatobiliary or pancreatic diseases were included. VTIQ elastography (Siemens ACUSON Sequoia, 5C-1 transducer) was used. SWV values were measured at the cephalic, corpus and tail of pancreas and replicated different operators' obtained data. Subgroups were classified according to the volunteers' gender, age, body mass index (BMI), depth of measurements and the echogenicity of the pancreas. RESULTS: From February 2023 to July 2023, 33 healthy adult volunteers were included. The success rate of VTIQ measurements in cephalic, corpus and tail regions was 90.90 % (30/33), 96.97 % (32/33) and 90.90 % (30/33) respectively. The color elastograms of healthy adult pancreas showed uniform blue or simultaneously blue and green. The average SWV values were 0.97±0.26 m/s for cephalic, 0.91±0.24 m/s for corpus and 0.97±0.25 m/s for pancreatic tail respectively (P = 0.198). The mean SWV values of pancreas did not show significant difference with age, gender or depth (P > 0.05). BMI was an influence factor in the measurements of SWV values of cephalic and tail of pancreas (P < 0.05). Pancreas with hyperechoic parenchyma showed higher mean SWV values (P < 0.05). The intra-observer (ICC = 0.938 [95% CI: 0.869–0.971]) and the inter-observer (ICC = 0.887 [95% CI: 0.760–0.947]) agreements of VTIQ measurements were excellent. CONCLUSIONS: The mean SWV value of the pancreas in healthy adults was 0.96±0.20 m/s (range: 0.52–1.74 m/s). VTIQ technique can be used in pancreatic stiffness measurements with good reliability. [ABSTRACT FROM AUTHOR]