Exploring 3D elastic-wave scattering at interfaces using high-resolution phased-array system.

The elastic-wave scattering at interfaces, such as cracks, is essential for nondestructive inspections, and hence, understanding the phenomenon is crucial. However, the elastic-wave scattering at cracks is very complex in three dimensions since microscopic asperities of crack faces can be multiple scattering sources. We propose a method for exploring 3D elastic-wave scattering based on our previously developed high-resolution 3D phased-array system, the piezoelectric and laser ultrasonic system (PLUS).

Universal Electrocardiographic Screening for Long QT Syndrome in Hospitalized Neonates.

Objective: Long QT syndrome (LQTS) is a known cause of unexpected death, leading some to recommend routine neonatal electrocardiographic (ECG) screening. We used continuous electronic heart rate corrected QT interval (QTc) monitoring to screen for interval prolongation in a cohort of hospitalized neonates to identify those at a risk of having LQTS. We hypothesized that this screening method would yield an acceptable positive predictive value (PPV).

Stress corrosion crack depth investigation using the time reversed elastic nonlinearity diagnostic.

Evidence of the ability to probe depth information of stress corrosion cracking (SCC) are presented using the time reversed elastic nonlinearity diagnostic (TREND). Depth estimation of SCC is important to determine when a stainless steel canister has been breached. TREND is a method to focus elastic energy to a point in space in order to probe that point for damage and its' depth penetration is used here to study depth information about SCC.

Three-dimensional time reversal communications in elastic media.

This letter presents a series of vibrational communication experiments, using time reversal, conducted on a set of cast iron pipes. Time reversal has been used to provide robust, private, and clean communications in many underwater acoustic applications. Here the use of time reversal to communicate along sections of pipes and through a wall is demonstrated to overcome the complications of dispersion and multiple scattering.

Predictive Ability of Direct Antibody Testing in Infants Born to Mothers with Rh(D) and Other Minor Red Blood Cell Antibodies.

Objective: Hemolytic disease of the newborn (HDN) most commonly occurs in neonates whose mothers carry nonpassively acquired antibodies directed against red blood cell (RBC) antigens. Because affected neonates may develop severe hyperbilirubinemia, early identification of at-risk neonates is critically important. We hypothesized that use of the direct antibody test (DAT) would be of high predictive value in identifying those neonates most likely to meet treatment criteria for hyperbilirubinemia.

Emergent thrombectomy in a neonate with an upper extremity arterial thrombus.

Case This case report is of a 39 (4/7)weeks infant who presented at the time of birth with an immobile, cyanotic right upper extremity consistent with ischemia but without evidence of gangrene. Doppler examination identified pulses in the axillary but not the brachial or radial arteries. Extremity arterial ultrasound confirmed the diagnosis of an arterial thrombosis extending from the right axillary artery to the brachial artery bifurcation.

Heart-rate-corrected QT interval evolution in premature infants during the first week of life.

Automated monitoring of the QT interval is increasingly common in a variety of clinical settings. A better understanding of how the heart-rate-corrected QT interval (QTc) evolves in early postnatal life is needed before its clinical utility in neonates can be determined. This study aimed to use real-time bedside monitoring as a tool to describe the QTc evolution of premature neonates during the first week of life.

Comparison and visualization of focusing wave fields from various time reversal techniques in elastic media.

This Letter presents a series of time reversal experiments conducted on the surface of a fused silica glass block. Four different time reversal techniques are compared using three different imaging conditions. The techniques include two classical time reversal experiments: one with a pulse waveform source and one with an impulse response generated from a chirp signal.

QTc interval prolongation and severe apneas associated with a change in infant positioning.

For more than a decade there has been considerable interest in the role of QT interval prolongation in the pathogenesis of sudden infant death syndrome. It has been proposed that the QT interval is a surrogate marker for autonomic instability and can be used to identify infants at risk for significant morbidity and mortality, including sudden infant death syndrome. We present the case of an infant that experienced a significant increase in his QTc, as detected by continuous QTc monitoring in the NICU after repositioning from a supine to prone position.

Time reversal reconstruction of finite sized sources in elastic media.

The ability of the time reversal process to reconstruct sources of finite size relative to a wavelength is investigated. Specifically the quality of the spatial reconstruction of a finite sized source will be presented through the use of time reversal experiments conducted on an aluminum plate. The data presented in the paper show that time reversal can reconstruct a source equally well regarding less of its size, when the source is a half wavelength or less in size.

Experimental implementation of reverse time migration for nondestructive evaluation applications.

Reverse time migration (RTM) is a commonly employed imaging technique in seismic applications (e.g., to image reservoirs of oil).