When a plane acoustic wave reaches a medium with an impedance infinite or null, it experiences a phase shift of zero or pi and its amplitude on the edge is maximum or vanishes. The case of a flexion wave (A0 Lamb wave) at a free end is also simple; its amplitude is multiplied by a factor 2 square root 2 and the phase shift is pi/2. The evanescent wave at the origin of these phenomena, perfectly described by the classical flexural plate theory, is identified as the imaginary A1 mode of the exact Rayleigh-Lamb theory. The experiences confirm the theoretical predictions.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1121/1.2749444 | DOI Listing |
Dokl Biochem Biophys
January 2025
Institute of Biomedical Problems, Russian Academy of Sciences, 123007, Moscow, Russia.
One of the most obvious manifestations of the negative impact of space flight factors on the human physiology is osteopenia. With the active development of manned space flights and the increase in the duration of humans' persistence in weightlessness, there is a growing need to understand the mechanisms of changes occurring at the cellular level involved in the replenishment of bone tissue. Using the RNA sequencing method, changes in the transcriptome profile of MMSCs were studied after a 5-day simulation of the microgravity effects.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
Atom interferometry shows high sensitivity for inertial measurements in the laboratory, but it faces difficulties in field applications because of a trade-off between sensitivity and size. Therefore, there is an urgent need to develop a small sensor with high resolution for measuring acceleration and rotation in inertial navigation applications. Presented here is a miniaturized inertial sensor capable of measuring acceleration and rotation simultaneously based on high-resolution dual atom interferometers.
View Article and Find Full Text PDFFront Public Health
January 2025
Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, United States.
Background: High dietary quality can protect against diet-related chronic diseases. In the United States, racial and ethnic minorities and those with lower incomes consistently exhibit lower dietary quality. Independently-owned restaurants are a common prepared food source in minority low-income communities, but there are significant knowledge gaps on how to work with these restaurants to offer healthy food, due to underlying and dynamic complexities associated with providing healthy food options.
View Article and Find Full Text PDFSci Rep
January 2025
School of Opto-electronics Engineering, Xi'an Technological University, Xi'an, 710021, China.
This paper explores a multi-directional (multiple directional) shearing synchronous polarization phase-shifting interferometer that utilizes a birefringent crystal displacer. This design effectively mitigates nonlinear issues and environmental influences commonly encountered in synchronous phase-shifting interferometry. Additionally, it enables the acquisition of shear wavefront information from multiple directions.
View Article and Find Full Text PDFInt J Hyperthermia
December 2025
Department of Mechanical Engineering, Brigham Young University, Provo, UT, USA.
Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) breast therapies, the focal location must be characterized to guide successful treatment. Focal characterization is difficult because heterogeneous breast tissues introduce phase aberrations that blur and shift the focus and traditional guidance methods do not work in adipose tissues. The purpose of this work is to evaluate numerical simulations of MRgFUS that predict the focal location.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!