A monochromatic, i.e. fixed frequency, back-scattering kernel measured at all angles does not uniquely determine the index of refraction in an inhomogeneous medium, nor can it guarantee any upper bound on the support of the inhomogeneity. We show that it is possible to associate with any such kernel its convex back-scattering support, a convex set which must be a subset of the convex hull of th...

Introduction In an environment of ultrahigh field (UHF) MRI, B1 + inhomogeneity causes contrast difference and spatially varying image signal in region-ofinterest (ROI). Recently, several designs of radiofrequency (RF) coils have been suggested to compensate this B1 + inhomogeneity. Using parallel transmission system [1-2] is also meaning for compensating B1 + inhomogeneity. However, most of av...

Water/fat separation in the presence of B 0 field inhomogeneity is a problem of considerable practical importance in MRI. This article describes two complementary methods for estimating the water/fat images and the field inhomogeneity map from Dixon-type acquisitions. One is based on variable projection (VARPRO) and the other on linear prediction (LP). The VARPRO method is very robust and can b...

We consider the Gierer-Meinhardt system with small inhibitor diffusivity, very small activator diffusivity and a precursor inhomogeneity. For any given positive integer k we construct a spike cluster consisting of k spikes which all approach the same nondegenerate local minimum point of the precursor inhomogeneity. We show that this spike cluster can be linearly stable. In particular, we show t...

Spiral wave propagation in oscillatory media with a disk-shaped inhomogeneity is examined. Depending on the properties of the medium as well as the inhomogeneity (different frequencies in two regions), distinct spiral waves including sinklike spirals and dense-sparse spirals, are able to emerge. We find that, unlike the previously found outward group velocity for spiral waves (normal spirals or...

Lung brachytherapy using high-dose rate (192)Ir technique is a well-established technique of radiation therapy. However, many commercial treatment planning systems do not have the ability to consider the inhomogeneity of lung in relation to normal tissue. Under such circumstances dose calculations for tissues and organs at risk close to the target are inaccurate. The purpose of the current stud...

BACKGROUND Atrial fibrillation (AF) is common after cardiac surgery. Abnormal conduction is an important substrate for AF. We hypothesized that atrial inflammation alters atrial conduction properties. METHODS AND RESULTS Normal mongrel canines (n=24) were divided into 4 groups consisting of anesthesia alone (control group); pericardiotomy (pericardiotomy group); lateral right atriotomy (atrio...

PURPOSE To evaluate age-related Meibomian gland (MG) changes by in vivo laser scanning confocal microscopy (LSCM). METHODS Asymptomatic healthy subjects (n=100, age range 20-83 years) with an Ocular Surface Disease Index score of less than 13 were consecutively enrolled. Two additional groups, one composed of subjects under 40 years of age (n=12) and one composed of subjects over 65 years (n=...

Aside from primordial gravitational instability of the cosmological fluid, various mechanisms have been proposed to generate large-scale structure at relatively late times, including, e.g., “late-time” cosmological phase transitions. In these scenarios, it is envisioned that the universe is nearly homogeneous at the time of last scattering and that perturbations grow rapidly sometime after the ...

A RE(rare earth)Ba2Cu3Ox (REBCO) high-temperature superconducting (HTS) coil is a promising candidate to achieve a nuclear magnetic resonance (NMR) magnet operated at a magnetic field >23.5 Tesla (T), i.e. 1 H NMR frequency of 1 GHz. We developed and tested a 400 MHz (9.39 T) NMR magnet using an REBCO inner coil. The system included a low-temperature superconducting (LTS) shim coil inside the R...