In our paper titled "Lamb Waves and Adaptive Beamforming for Aberration Correction in Medical Ultrasound Imaging" [1], we mentioned that the superposition of the different symmetric (S) modes in the frequency-wavenumber (f-k) domain results in a high intensity region where its slope corresponds to the longitudinal wave speed in the slab. However, we have recently understood that this high intensity region belongs to the propagation of a wave called lateral wave or head wave [2-5]. It is generated if the longitudinal sound speed of the aberrator (i.e. the PVC slab) is larger than that of water and if the incident wavefront is curved. When the incidence angle at the interface between water and PVC is near the critical angle, the refracted wave in PVC re-radiates a small part of its energy into the fluid (i.e. the head wave). As discussed in [4], if the thickness of the waveguide is larger than the wavelength, the first arriving signal is the head wave. This is also the case in our study [1] where the ultrasound wavelength of a compressional wave in PVC was close to 1 mm, and a PVC slab with a thickness of 8 mm was used.
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http://dx.doi.org/10.1109/TUFFC.2020.3045936 | DOI Listing |
Med J Armed Forces India
January 2024
Professor & Head, Department of Internal Medicine, Armed Forces Medical College, Pune, India.
Vitamin D deficiency is commonly seen in the general population, likely due to lack of adequate exposure to sunlight as well as lack of sufficient dietary intake. However, severe hypocalcemia secondary to vitamin D deficiency, manifesting as seizures is uncommon. We present a series of such cases encountered by us in the time frame of June 2020 to Dec 2021 (the first wave of the Covid-19 pandemic associated with a lockdown) during which patients of varying age groups presented with seizures.
View Article and Find Full Text PDFUltrasound Med Biol
January 2025
School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan ROC; Center of Physical Therapy, National Taiwan University Hospital, Taipei, Taiwan ROC. Electronic address:
Objective: This study aimed to validate the ultrasound speckle tracking (UST) algorithm, determine the optimal probe location by comparing normalized cross-correlation (NCC) values of muscle displacement at two locations (proximal vs. middle) of the biceps femoris long head (BFlh) using the UST, and investigate the effects of Nordic hamstring curl exercise (NHE) training on BFlh displacement.
Methods: UST efficacy was verified with ex vivo uniaxial testing of porcine leg muscles.
Aerosp Med Hum Perform
January 2025
Introduction: In space, under weightlessness conditions, human brain activity is changed due to the shifting of body fluid and blood toward the cephalic region. This shifting leads to changes in cerebral hemodynamics and, consequently, neurophysiological function, which impacts mental functions like cognition and decision-making capabilities of space travelers. The present study reports the effect of acute exposure to simulated microgravity on cognitive functions and event-related potentials.
View Article and Find Full Text PDFBrain Sci
January 2025
Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Zurich, University of Zurich, 8006 Zurich, Switzerland.
The brainstem auditory-evoked response (BAER) is an established electrophysiological measure of neural activity from the auditory nerve up to the brain stem. The BAER is used to diagnose abnormalities in auditory pathways and in neurophysiological human and animal research. However, normative data for BAERs in sheep, which represent an adequate large animal model for translational and basic otological research, are lacking.
View Article and Find Full Text PDFJ Ultrason
December 2024
Department of General and Pediatric Radiology, Wrocław Medical University, Wrocław, Poland.
Aim: Chronic hepatitis C virus infections can lead to liver fibrosis. Appropriate treatment of chronic hepatitis C may result in significant fibrosis reversal. The best method to assess liver fibrosis is an invasive hepatic biopsy.
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