Introduction: In spoiled gradient-recalled echo pulse sequences, the standard RF spoiling scheme uses an ever increasing phase angle of the RF pulse and crusher gradients to spoil the transverse magnetization [1]: φn=φn-1+nφseed. Optimal ideal seed values have been arrived at either from experimentation or simulation for a particular set of imaging parameters or cost function [2,3]. The paramet...

In order to develop a fine angular beam steering technique (milliradian and less), we propose a nematic liquid crystal cell with a continuous gradient of the refractive index. This continuous gradient is controlled by applying the driving voltage to non-patterned indium-tin oxide electrodes. We employed the dual-frequency nematic liquid crystal in the cell with high pretilt alignment. The exper...

Carr-Purcell-Meiboom-Gill train of radiofrequency pulses applied to spins in the constant magnetic field gradient is an efficient variant of the modulated magnetic field gradient spin echo method, which provides information about molecular diffusion in the frequency-domain instead in the time-domain as with the two-pulse gradient spin echo. The frequency range of novel technique is broad enough...

A premature stop codon in ACTN3 resulting in α-actinin-3 deficiency (the ACTN3 577XX genotype) is common in humans and reduces strength, muscle mass, and fast-twitch fiber diameter, but increases the metabolic efficiency of skeletal muscle. Linkage disequilibrium data suggest that the ACTN3 R577X allele has undergone positive selection during human evolution. The allele has been hypothesized to...

Gradient enhanced high resolution NMR has become a standard method in recent years, where B0 gradients are employed to increase the selectivity of conventional magnetic resonance methods. Radio frequency gradient methods permit greater flexibility in experiment design, and this thesis is concerned with developing the necessary theoretical background for understanding and developing RF gradient ...

1. INTRODUCTION When put into the magnetic field, a tiny but detectable fraction of the protons present in water in the body will align with this strong, steady magnetic field. During imaging, the tissue of interest is occasionally subjected to a brief electromagnetic radio-frequency (RF) pulse, essentially tilting the aligned protons off the axis of the main magnetic field. The protons then pr...

Among all forms of routine human activity, the one which produces the strongest gravity-gradient noise in interferometric gravitational-wave detectors ~e.g. LIGO! is the beginning and end of weight transfer from one foot to the other during walking. The beginning and end of weight transfer entail sharp changes ~time scale t;20 msec! in the horizontal jerk ~first time derivative of acceleration!...

Spectroscopic imaging of a sample placed outside of both the radio frequency and the imaging gradient coils is presented. The sample is placed in a field with a permanent one-dimensional inhomogeneity. The imaging gradients used for phase encoding are designed to produce a static field that depends only on the transverse direction, uncoupling the effects associated with the single-sided nature ...

SLAC is studying the feasibility of using an X-band RF photocathode gun to produce low emittance bunches for applications such as a mono-energetic MeV γ ray source (in collaboration with LLNL) and a photoinjector for a compact FEL. Beam dynamics studies are being done for a configuration consisting of a 5.5-cell X-band gun followed by several 53-cell high-gradient X-band accelerator structures....

A multiple-iteration constrained conjugate gradient (MICCG) algorithm and a single-iteration constrained conjugate gradient (SICCG) algorithm are proposed to realize the widely used frequency-domain minimum-variance-distortionless-response (MVDR) beamformers and the resulting algorithms are applied to speech enhancement. The algorithms are derived based on the Lagrange method and the conjugate ...