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Objective: High‐resolution esophageal manometry (HRM) is the gold standard for the diagnosis of esophageal motility disorders. HRM is typically performed in the office with local anesthesia only, and many patients find it unpleasant and painful. The aim of this study was to examine the effects of the use of a virtual reality (VR) headset on pain and anxiety outcomes in patients with dysphagia undergoing HRM. Methods: Patients with dysphagia were prospectively recruited and randomized to undergo HRM with and without VR distraction. Data collected included the State‐Trait Anxiety Inventory‐6 (STAI‐6), the Short‐Form McGill Pain Questionnaire, heart rate, and galvanic skin response (GSR) tracings. Results: Forty subjects completed the study, including 20 subjects in the intervention arm and 20 in the control arm. There was evidence of a significant positive effect of VR on calmness (p = 0.0095) STAI‐6 rating, as well as on physiologic measures of pain with significantly decreased GSR rise time (p = 0.0137) and average rate of change of conductance change (p = 0.0035). Conclusion: The use of VR during HRM catheter insertion increased calmness compared to control. Change of skin conductance was also reduced in the VR group, suggesting decreased physiologic pain. This study supports the consideration of the use of VR as a distraction tool to improve patient comfort during HRM. Level of Evidence: 2 Laryngoscope, 134:1118–1126, 2024 [ABSTRACT FROM AUTHOR]

Both endometriosis and irritable bowel syndrome (IBS) are commonly found in young women and the diagnosis of either is challenging. Alarm symptoms can exclude the diagnosis of IBS, but their onset may be insidious and often no evidence of organic disease may be found. We present a patient with a 4-year history of presumed IBS, absent gynecological symptoms, negative gastrointestinal as well as gynecological testing who developed the only alarm symptom of weight loss and was eventually found to have endometriosis of the small intestine. This case illustrates the need for constant vigilance in patients with IBS.

This work is concerned with developing radar signaling strategies and algorithms that enhance the ability of a synthetic aperture radar (SAR) to image targets in the presence of digital radio frequency memory (DRFM) repeat jammers. The approach is based on a manipulation/alteration of the transmitted signal and/or its parameters in the fast-time domain at every position of the synthetic aperture (pulse repetition interval (PRI)); this scheme is known as pulse diversity. In particular, we utilize a modulated form of the transmitted chirp signal and/or vary the rate of the chirp at each PRI; the modulation and/or the rate is varied from one PRI to another, and these variations are only known to the user. The merits of these pulse diversity methods are studied using the autocorrelation and cross-correlation of these signals. We also present a signal processing method for penalizing a DRFM jammer that tries to repeat the radar signal.

This paper addresses change detection in averaged multilook synthetic aperture radar (SAR) imagery. Averaged multilook SAR images are preferable to full-aperture SAR reconstructions when the imaging algorithm is approximation-based (e.g., polar format processing) or when motion data are not accurate over a long full aperture. We examine the application of a SAR change-detection method, known as signal subspace processing, which is based on the principles of two-dimensional adaptive filtering, and we use it to recognize the addition of surface landmines to a particular area under surveillance. We describe the change-detection problem as a trinary hypothesis testing problem, and define a change signal and its normalized version to determine whether: 1) there is no change in the imaged scene; 2) a target has entered the imaged scene; or 3) a target has exited the imaged scene. A statistical analysis of the error signal is provided to show its properties and merits. Results are presented for averaged noncoherent multilook and coherent single-look X-Band SAR imagery. Index Terms--Change detection, multiiook processing, signal subspace processing (SSP), synthetic aperture radar (SAR).

The results of three-dimensional (3-D) imaging of a T-72 tank using its angular azimuthal (turntable) and linear elevation synthetic aperture data at X band are presented. This is achieved using an accurate and computationally efficient wavefront (Fourier-based) reconstruction algorithm for elevation and circular (E-CSAR) data. The E-CSAR 3-D images are then used to synthesize 2-D spotlight and stripmap slant plane synthetic aperture radar (SAR) images of the target at a desired range and squint angle. For this purpose, a procedure is introduced that incorporates the spatially varying azimuthal and elevation Doppler signatures of individual reflectors on the target as well as the mean range, azimuth, and elevation of the flight path. Results using the E-CSAR images of the T-72 tank are provided.

Moving target detection and imaging results for an X band spotlight synthetic aperture radar (SAR) system that utilizes an along-track monopulse configuration for its data collection is presented. The theoretical foundation of the processing that is used on these data is based on our earlier work in which a two-dimensional signal subspace processing (adaptive filtering) method was used to calibrate the monostatic and bistatic radars of the monopulse SAR system. The blind calibration of the two channels enables the user to null the stationary scene, and detect the moving targets. Next, a measure that we call SAR ambiguity function is used to estimate the relative speed of a detected moving target. The resultant estimate is then used to image the moving target.

This research is concerned with multidimensional signal processing and image formation with FOliage PENetrating (FOPEN) airborne radar data which were collected by a Navy P-3 ultra wideband (UWB) radar in 1995 [6, 11, 12]. The digital signal processors that were developed for the P-3 data commonly used a radar beamwidth angle that was limited to 35 deg [2, 8]. Provided that the P-3 radar beamwidth angle (after slow-time FIR filtering and 6:1 decimation) was 35 deg, the P-3 signal aperture radar (SAR) system would approximately yield alias-free data in the slow-time Doppler domain. We provide an analysis here of the slow-time Doppler properties of the P-3 SAR system. This study indicates that the P-3 database possesses a 50 deg beamwidth angle within the entire [215, 730] MHz band of the P-3 radar. We show that the 50-degree beamwidth limit is imposed by the radar (radial) range swath gate; a larger beamwidth measurements would be possible with a larger range swath gate. The 50-degree beamwidth of the P-3 system results in slow-time Doppler aliasing within the frequency band of [444,730] MHz. We outline a slow-time processing of the P-3 data to minimize the Doppler aliasing. The images which are formed via this method are shown to be superior in quality to the images which are formed via the conventional P-3 processor [2]. In the presentation, we also introduce a method for converting the P-3 deramped (range-compressed) data into its alias-free baseband echoed data; the utility of this conversion for suppressing radio frequency interference (RFI) signals is shown.

A time-saving method is described for obtaining image data collection, based on a Fourier approach for image formation. The process is applicable to both near-field and far-field scenarios, and requires no restrictions on target area size, aperture size, or radiation frequency.

The use of spiral scan data eliminates problems in the multiresolution representation of dynamic images. Experiments confirming this finding were performed using spatial sampling on uniform density and foveal methods of spiral scan data collection. The target motion and spiral scan data acquisition system were modeled on two fast-time and slow-time variables to capture a moving target. Moreover, the forward and backward spiral scans are recommended to enhance the repetition rate of the spiral data acquisition system.

Experimentation with a system model for airborne synthetic acoustic (SAA) image which incorporates the vehicle's speed produced improved accuracy compared to the synthetic aperture radar model. The model uses wave propagaton concepts to account for the speed of the vehicle relative to the target region while the inversion uses spectral decomposition of spherical phase functions. The principles used in this airborne SAA system can also be used for passive SAA systems.

A method is presented for detecting moving targets which are hidden in foliage. Finding moving targets is difficult because the image of the target is weak compared to the surrounding foliage which cannot be filtered out. The method involves two Synthetic Aperture Radar Systems (SAR) being fixed onto a single aircraft and they have a common range and altitude. The monopulse SAR images enable difference and interferometric images to be built up.

A phased array system for spatial-velocity imaging of mobile targets is examined. It repetitively illuminates the target area with a transmit beam which may hold a quadratic delay across the array aperture for area focusing. A linear delay is introduced on the array aperture for beam steering in the receive mode at every pulse transmission. The procedure is also employed to image stationary targets.

An interferometric processing of an airplane's monostatic and bistatic inverse synthetic aperture radar (ISAR) signatures for automatic landing is shown. The airplane's squint angle is almost 90 degrees. This extreme squint angle is ably handled by the ISAR Fourier-based reconstruction algorithm. The airplace can be imaged accurately without any erroneous shifts in the cross-range domain, within the imposed theoretical resolution.

A slant plane circular synthetic aperture radar system is able to extract three dimensional imaging information of a target scene. The two types of ultra wideband ultrahigh frequency radar signatures, foliage penetrating and ground penetrating, vary with the radar's aspect angle. The concerned model is based on the Fourier analysis of the slant plane Green's function. Advantages of the model can be demonstrated by using an aircraft as a simulated target. However, a reconstruction based on partial segment of the circular synthetic aperture gives limited shape information.

Noninvasive vibration diagnostic techniques are implemented to assess the mechanical condition of power circuit breakers. A diagnostic system, the Prototype Commercial Portable Diagnostic System (PCPDS) has been developed. Hardware of the PCPDS includes a portable computer, and a data acquisition unit and computer communication canis. Signal processing techniques include the discrete energy statistics envelope, short-time power spectrum, tinting extraction algorithm and chi-square based shape test. Decision-making is carded out via a voter program, to which individual results from the timing and shape analysis programs are passed. Statistical and empirical thresholds have been established, that classify the circuit breaker as being in Normal-Transitional-Abnormal (Green-Yellow-Red) condition.

Two iterative alogrithms with their own varying coefficient help reconstruct a band-limited function from the unevenly spaced sampled data. Minimization of error energy reduction of the data and of error energy of the signal help determine the varying coefficients for the two iterative algorithms, respectively. The reconstructed signal displays convergence in the presence of a sampling set that allows the nonharmonic Fourier functions to develop into a complete set in the subspace of the signal.

A system model is presented for a synthetic aperture radar (SAR)/inverse SAR system employed in imaging a moving target in a stationary background. It characterizes the relationship between the radar signal and moving target such that a spatial Fourier decomposition of the SAR signal leads to the estimation of the moving target's velocity via a spatial Doppler technique. This facilitates a squint-mode SAR imaging solution to the original SAR imaging problem.

A system model and a procedure are proposed for inversion of phased array scan data to facilitate simplified array imaging in the two-dimensional spatial domain. The method employs either time domain sampling of the beam-steered data or temporal frequency sweep instead of range focusing to obtain the spatial Fourier transform reflectivity function. Factors relating to the method's implementation, sampling restrictions and imaging resolution are also discussed.

Two types of multiplicative noise in synthetic aperture radar (SAR) imaging are encountered by methods which involve the reconstruction of phase from amplitude. The wave-derived perturbation solution properties of SAR data serve as the basis of the methods. This perturbation solution is transformed into a noniterative analytical solution in the context of moments and powers of the log amplitude function. Other methods involve the consideration of multiplicative noise with a complex phase which differs linearly with reference to the radar signal temporal frequencies. The complex phase error function is reconstructed using two wave equations which govern the SAR signal.

Inverse techniques for ground plane and slant plane synthetic aperture radar (SAR)/inverse SAR imaging are presented in a study that employs a system model. The latter takes into account the spherical radiation pattern of a radar signal at far field. The method subsequently developed carries out Doppler processing on signals depending on the coordinates of the SAR or ISAR. An analysis of the outcome on imaging resolution, reconstruction and sampling constraints by a finite aperture is also shown.

Monitoring whole body composition (fat mass and fat-free mass) in preterm infants may assist in optimizing nutrition and promoting growth and neurodevelopment in the neonatal intensive care unit. Currently, body composition assessment is not part of routine clinical evaluation of premature infants. Instead, weight and length are used to assess growth but are known to be poor predictors of adiposity shortly after birth. Although body composition methods, such as magnetic resonance imaging, stable-isotope dilution, and dual-energy x-ray absorptiometry, have been examined in infants, they involve exposure to radiation and are invasive, expensive, and/or unsuitable for repeated measurements in a medically fragile population. Several body composition methods with potential for clinical use have been explored in premature infants, including air displacement plethysmography, bioimpedance, skinfold measurements, and ultrasound. In this review, we examine each method and evaluate its feasibility for incorporation into clinical care. Although these methods show promise for use in premature infants, further research is needed before they can be recommended for routine body composition assessment in the clinical setting. [ABSTRACT FROM AUTHOR]

A mathematical model for analyzing the problem of fusing information in uncalibrated sensors is presented. The model is able to develop a signal subspace processing for fusing uncalibrated sensors by relating one image to a linear combination of the other image, its powers and their spatially transformed versions. Experimental results showed that the model is applicable for moving target detection using a monopulse synthetic aperture radar with uncalibrated radars.

Coherent signal processing methods for combining the data that are collected via a multi-channel airborne radar system for moving target detection and image formation, are examined. Methods that convert multi-channel radar data into dual along-track monopulse synthetic aperture radar (SAR) signals of the radiated scene, are studied. A two-dimensional adaptive filtering method that projects the data in one synthesised SAR channel into the signal subspace of the other, is used for blind calibration of the monopulse SAR signals and generation of the moving target indication statistic. The merits of these algorithms are studied using the data from the multi-channel airborne radar measurement system that has been developed by the Air Force Research Laboratory at Rome, New York. [ABSTRACT FROM AUTHOR]

This letter describes the extension of signal subspace processing (SSP) to the arena of anomaly detection. In particular, we develop an SSP-based, local anomaly detector that exploits the rich information available in the multiple bands of a hyperspectral (HS) image. This SSP approach is based on signal processing considerations, and its entire formulation reduces to a straightforward (and intuitively pleasing) geometric and algebraic development. We extend the basic SSP concepts to the HS anomaly detection problem, develop an SSP HS anomaly detector, and evaluate this algorithm using multiple HS data files [ABSTRACT FROM PUBLISHER]

A scanning laser acoustic microscope (SLAM) is described. The SLAM achieves a resolution of about 10 μm and is capable of imaging subsurface features at depths up to several millimeters, using appropriate reconstruction algorithms. The various components of the apparatus, both acousto-optical and electronic, are described. A major feature of the SLAM is a digital data-acquisition system capable of storing and processing the complex acoustic field in images with 256×256-pixel resolution. An array processor enables most floating-point operations to be completed in a few seconds. Examples of acoustic images obtained from a test sample are presented. [ABSTRACT FROM AUTHOR]