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Shear wave

V L R Jacques, C Laulhé, N Moisan, S Ravy, D Le Bolloc'h
We report on time-resolved x-ray diffraction measurements following femtosecond laser excitation in pure bulk chromium. Comparing the evolution of incommensurate charge-density-wave (CDW) and atomic lattice reflections, we show that, a few nanoseconds after laser excitation, the CDW undergoes different structural changes than the atomic lattice. We give evidence for a transient CDW shear strain that breaks the lattice point symmetry. This strain is characteristic of sliding CDWs, as observed in other incommensurate CDW systems, suggesting the laser-induced CDW sliding capability in 3D systems...
October 7, 2016: Physical Review Letters
Mafalda Magalhães, Pedro Belo-Oliveira, João Casalta-Lopes, Yessica Costa, Manuela Gonçalo, Paula Gomes, Filipe Caseiro-Alves
RATIONALE AND OBJECTIVES: The aim of this study was to correlate acoustic radiation force impulse (ARFI) imaging velocities with the pathology results and to evaluate the ability of ARFI in distinguishing benign from malignant breast lesions. MATERIALS AND METHODS: B-mode ultrasonography (US) and ARFI were performed in patients with previously diagnosed and selected breast lesions for biopsy. Shear wave velocity (SWV) was measured inside lesions and in the surrounding parenchyma (m/s)...
October 17, 2016: Academic Radiology
Jiang Zhu, Li Qi, Yusi Miao, Teng Ma, Cuixia Dai, Yueqiao Qu, Youmin He, Yiwei Gao, Qifa Zhou, Zhongping Chen
Elastography provides a powerful tool for histopathological identification and clinical diagnosis based on information from tissue stiffness. Benefiting from high resolution, three-dimensional (3D), and noninvasive optical coherence tomography (OCT), optical micro-elastography has the ability to determine elastic properties with a resolution of ~10 μm in a 3D specimen. The shear wave velocity measurement can be used to quantify the elastic modulus. However, in current methods, shear waves are measured near the surface with an interference of surface waves...
October 20, 2016: Scientific Reports
Donato Belmonte, Carlo Gatti, Giulio Armando Ottonello, Pascal Richet, Marino Vetuschi Zuccolini
Thermodynamic and thermophysical properties of Na2SiO3 in the Cmc21 structural state are computed ab-initio using the hybrid B3LYP density functional method. The static properties at the athermal limit are first evaluated through a symmetry-preserving relaxation procedure. The thermodynamic properties that depend on vibrational frequencies viz, heat capacities, thermal expansion, thermal derivative of the bulk modulus, thermal correction to internal energy, enthalpy, Gibbs free energy, are then computed in the framework of quasi-harmonic approximation...
October 19, 2016: Journal of Physical Chemistry. A
Ryan E Stafford, Rafeef Aljuraifani, François Hug, Paul W Hodges
OBJECTIVES: To investigate whether increases in stiffness can be detected in the anatomical region associated with the striated urethral sphincter during voluntary activation using shear wave elastography; to identify the location and area of the stiffness increase relative to the point of greatest dorsal displacement of the mid urethra (i.e. striated urethral sphincter); and to determine the relationship between muscle stiffness and contraction intensity. SUBJECTS AND METHODS: Ten healthy men participated...
October 18, 2016: BJU International
Yan Ma, Shuo Zhang, Jing Li, Jianyi Li, Ye Kang, Weidong Ren
OBJECTIVE: To compare the diagnostic performances of strain elastography (SE) and shear-wave elastography (SWE) for predicting response to neoadjuvant chemotherapy (NACT) in patients with breast cancer. METHODS: This prospective study recruited 71 eligible patients from June 2014 to May 2016. All patients provided written informed consent. Tumour stiffness was assessed by the SE strain ratio (R), SWE maximum elasticity (Emax) and SWE mean elasticity (Emean). Ultrasonic elastography (UE) assessments were performed at each NACT cycle (t1 - t6)...
October 17, 2016: European Radiology
Frank W DiPaola, Kurt R Schumacher, Caren S Goldberg, Joshua Friedland-Little, Aishwarya Parameswaran, Jonathan R Dillman
OBJECTIVES: Assess liver stiffness using ultrasound point shear wave elastography (US P-SWE) in children before and after the Fontan operation. METHODS: Eighteen children undergoing the Fontan operation were prospectively enrolled. Eight US P-SWE measurements were obtained from the right hepatic lobe before surgery, and at multiple postoperative time points. Temporally related inferior vena cava pressure (IVC) data was collected from medical records, when available...
October 17, 2016: European Radiology
Ryan J Gallacher, Derek Keir, Nicholas Harmon, Graham Stuart, Sylvie Leroy, James O S Hammond, J-Michael Kendall, Atalay Ayele, Berhe Goitom, Ghebrebrhan Ogubazghi, Abdulhakim Ahmed
Melting of the mantle during continental breakup leads to magmatic intrusion and volcanism, yet our understanding of the location and dominant mechanisms of melt generation in rifting environments is impeded by a paucity of direct observations of mantle melting. It is unclear when during the rifting process the segmented nature of magma supply typical of seafloor spreading initiates. Here, we use Rayleigh-wave tomography to construct a high-resolution absolute three-dimensional shear-wave velocity model of the upper 250 km beneath the Afar triple junction, imaging the mantle response during progressive continental breakup...
October 18, 2016: Nature Communications
Noriyoshi Tsujino, Yu Nishihara, Daisuke Yamazaki, Yusuke Seto, Yuji Higo, Eiichi Takahashi
Seismic shear wave anisotropy is observed in Earth's uppermost lower mantle around several subducted slabs. The anisotropy caused by the deformation-induced crystallographic preferred orientation (CPO) of bridgmanite (perovskite-structured (Mg,Fe)SiO3) is the most plausible explanation for these seismic observations. However, the rheological properties of bridgmanite are largely unknown. Uniaxial deformation experiments have been carried out to determine the deformation texture of bridgmanite, but the dominant slip system (the slip direction and plane) has not been determined...
October 17, 2016: Nature
Tao Wu, Ping Wang, Ting Zhang, Jian Zheng, Shuoyang Li, Jie Zeng, Masatoshi Kudo, Rongqin Zheng
BACKGROUND: Noninvasive assessment of liver fibrosis has important clinical significance. Different techniques including two-dimensional shear-wave elastography (2D SWE) and real-time tissue elastography (RTE) are reported to be useful for the noninvasive diagnosis of hepatic fibrosis. All these techniques are affected by many factors. How to choose a reasonable method needs further studies. PURPOSE: This study was conducted to comparatively assess the diagnostic performance of 2D SWE and RTE in patients with Chronic Hepatitis B (CHB) and influence of inflammation on the stiffness values obtained by both techniques, so as to objectively assess the reasonable choice between these 2 elastography techniques for noninvasive assessment of hepatic fibrosis in clinical practice...
2016: Digestive Diseases
Koushik Viswanathan, Narayan K Sundaram, Srinivasan Chandrasekar
Stick-slip in sliding of soft adhesive surfaces has long been associated with the propagation of Schallamach waves, a type of slow surface wave. Recently it was demonstrated using in situ experiments that two other kinds of slow waves-separation pulses and slip pulses-also mediate stick-slip (Viswanathan et al., Soft Matter, 2016, 12, 5265-5275). While separation pulses, like Schallamach waves, involve local interface detachment, slip pulses are moving stress fronts with no detachment. Here, we present a theoretical analysis of the propagation of these three waves in a linear elastodynamics framework...
October 17, 2016: Soft Matter
Molly A B Blank, James F Antaki
In this systematic review and meta-analysis, we report measured elasticities of benign and malignant breast pathologies from shear wave elastography (SWE), quantitatively confirm the effect of the selected region of interest (ROI) on these measures and test the hypothesis that a metric of heterogeneity based on the mean and maximum elasticity can improve specificity of diagnosis. The elasticities of benign, malignant and specific pathologic states are reported from 22 publications encompassing 2989 patients, identified from a structured search of the literature from May to September 2015...
October 14, 2016: Ultrasound in Medicine & Biology
David Taylor
Experiments and observations were carried out to investigate the response to impact of the shells of the limpet Patella vulgata. Dropped-weight impact tests were conducted, creating damage which usually took the form of a hole in the shell's apex. Similar damage was found to occur naturally, presumably as a result of stones propelled by the sea during storms. Apex holes were usually fatal, but small holes were sometimes repaired, and the repaired shell was as strong as the original, undamaged shell.The impact strength (energy to failure) of shells tested in situ was found to be 3...
October 14, 2016: Journal of Experimental Biology
Sébastien Aubry, Jean-Philippe Nueffer, Mathieu Carrié
In highly anisotropic biological tissues such as muscle or tendons, calculating Young's modulus from the shear wave speed (csw) by using shear wave elastography (SWE) involves a complex transversally isotropic rheological model not yet used in common practice. To our knowledge, the effect of muscle anisotropy on csw of intra-muscular lesions has not yet been investigated. The objective of our study was to define the effect of an anisotropic medium on csw of intra-muscular gelatinous inclusions. We conducted a prospective monocentric, in vitro study in order to examine the quantitative and qualitative SWE behavior of a 9-mm gelatinous intra-muscular implant depending on the orientation of the probe relative to the muscle fibers...
October 11, 2016: Ultrasound in Medicine & Biology
Yan-Lin Liu, Guo-Yang Li, Ping He, Ze-Qi Mao, Yanping Cao
Determining the mechanical properties of brain tissues is essential in such cases as the surgery planning and surgical training using virtual reality based simulators, trauma research and the diagnosis of some diseases that alter the elastic properties of brain tissues. Here, we suggest a protocol to measure the temperature-dependent elastic properties of brain tissues in physiological saline using the shear wave elastography method. Experiments have been conducted on six porcine brains. Our results show that the shear moduli of brain tissues decrease approximately linearly with a slope of -0...
September 21, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Mainak Mookherjee, David Mainprice, Ketan Maheshwari, Olle Heinonen, Dhenu Patel, Anant Hariharan
Albite (NaAlSi3O8) is an aluminosilicate mineral. Its crystal structure consists of 3-D framework of Al and Si tetrahedral units. We have used Density Functional Theory to investigate the high-pressure behavior of the crystal structure and how it affects the elasticity of albite. Our results indicate elastic softening between 6-8 GPa. This is observed in all the individual elastic stiffness components. Our analysis indicates that the softening is due to the response of the three-dimensional tetrahedral framework, in particular by the pressure dependent changes in the tetrahedral tilts...
October 13, 2016: Scientific Reports
Shiteng Zhao, Bimal Kad, Bruce A Remington, Jerry C LaSalvia, Christopher E Wehrenberg, Kristopher D Behler, Marc A Meyers
Solid-state shock-wave propagation is strongly nonequilibrium in nature and hence rate dependent. Using high-power pulsed-laser-driven shock compression, unprecedented high strain rates can be achieved; here we report the directional amorphization in boron carbide polycrystals. At a shock pressure of 45∼50 GPa, multiple planar faults, slightly deviated from maximum shear direction, occur a few hundred nanometers below the shock surface. High-resolution transmission electron microscopy reveals that these planar faults are precursors of directional amorphization...
October 12, 2016: Proceedings of the National Academy of Sciences of the United States of America
Harald Kramer, Perry J Pickhardt, Mark A Kliewer, Diego Hernando, Guang-Hong Chen, James A Zagzebski, Scott B Reeder
OBJECTIVE: The purpose of this study was to prospectively evaluate the accuracy of proton-density fat-fraction, single- and dual-energy CT (SECT and DECT), gray-scale ultrasound (US), and US shear-wave elastography (US-SWE) in the quantification of hepatic steatosis with MR spectroscopy (MRS) as the reference standard. SUBJECTS AND METHODS: Fifty adults who did not have symptoms (23 men, 27 women; mean age, 57 ± 5 years; body mass index, 27 ± 5) underwent liver imaging with un-enhanced SECT, DECT, gray-scale US, US-SWE, proton-density fat-fraction MRI, and MRS for this prospective trial...
October 11, 2016: AJR. American Journal of Roentgenology
S Murphy, A Scala, A Herrero, S Lorito, G Festa, E Trasatti, R Tonini, F Romano, I Molinari, S Nielsen
The 2011 Tohoku earthquake produced an unexpected large amount of shallow slip greatly contributing to the ensuing tsunami. How frequent are such events? How can they be efficiently modelled for tsunami hazard? Stochastic slip models, which can be computed rapidly, are used to explore the natural slip variability; however, they generally do not deal specifically with shallow slip features. We study the systematic depth-dependence of slip along a thrust fault with a number of 2D dynamic simulations using stochastic shear stress distributions and a geometry based on the cross section of the Tohoku fault...
October 11, 2016: Scientific Reports
Aditya B Singaraju, Kyle Nguyen, Abhay Jain, Rahul V Haware, Lewis L Stevens
The tableting performance for p-aminobenzoic acid (PABA) and a series of its benzoate esters with increasing alkyl chain length (methyl-, ethyl- and n-butyl) was determined over a broad range of compaction pressures. The crystalline structure of methyl benzoate (Me-PABA) exhibits no slip systems and does not form viable compacts under any compaction pressure. The ethyl (Et-PABA) and n-butyl (Bu-PABA) esters each have a similar, corrugated-layer structure that displays a prominent slip plane and improves material plasticity at low compaction pressure...
October 10, 2016: Molecular Pharmaceutics
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