Related papers: T2 Relaxation during Radiofrequency (RF) pulses
A wide variety of nuclear magnetic resonance experiments rely on the prediction and analysis of relaxation processes. Recently, innovative approaches have been introduced where the sample travels through a broad range of magnetic fields in…
Terahertz (THz) communication ensures the provision of ultra-high data rates owing to its abundant bandwidth; however, its performance is impeded by complex propagation mechanisms. In particular, molecular absorption induces a temporal…
The nuclear magnetic resonance signal from sodium (23Na) nuclei demonstrates a fast bi-exponential T2 decay in biological tissues (T2,short = 0.5-5 ms and T2,long = 10-30 ms). Hence, blurring observed in sodium images acquired with…
Time reversal (TR) focusing of ultrasound in granular packings is experimentally investigated. Pulsed elastic waves transmitted from a compressional or shear transducer source are measured by a TR mirror, reversed in time and…
Purpose: Designing a new T2 preparation (T2-Prep) module in order to simultaneously provide robust fat suppression and efficient T2 preparation without requiring an additional fat suppression module for T2-weighted imaging at 3T. Methods:…
Pulsar timing has enabled some of the strongest tests of fundamental physics. Central to the technique is the assumption that the detected radio pulses can be used to accurately measure the rotation of the pulsar. Here we report on a…
Purpose: To evaluate safety of MRI in patients with fragmented retained leads (FRLs) through numerical simulation and phantom experiments. Methods: Electromagnetic and thermal simulations were performed to determine the worst-case RF…
This study presents a comparison of quantitative MRI methods based on an efficiency metric that quantifies their intrinsic ability to extract information about tissue parameters. Under a regime of unbiased parameter estimates, an intrinsic…
We collect 133 Fast Radio Bursts (FRBs), including 110 non-repeating and 23 repeating ones, and systematically investigate their observational properties. To check the frequency dependence of FRB classifications, we define our samples with…
Pulsed electron paramagnetic resonance measurements of donor electron spins in natural phosphorus-doped silicon (Si:P) and isotopically-purified 28Si:P show a strongly temperature-dependent longitudinal relaxation time, T1, due to an Orbach…
I describe a method for generating "shim pulses" for NMR spectroscopy and imaging (MRI) by taking advantage of the inherent inhomogeneity in the static and radiofrequency (RF) fields of a one-sided NMR system. The RF inhomogeneity here is…
Low-field T2 mapping MRI can democratize neuropediatric imaging by improving accessibility and providing quantitative biomarkers of brain development. \textbf{Purpose:} To evaluate the feasibility of high-resolution T2 mapping using a…
New, fundamental resonant properties of laser resonators are theoretically predicted and experimentally demonstrated. These resonances occur either in the time dependence of the beam width and that of beam radius of curvature of the…
We show that ultrashort pulses can be focused, in a particular instant, to a spot size given by the wavelength associated with its spectral width. For attosecond pulses this spot size is within the nanometer scale. Then we show that a…
The photoresponse of YBa2Cu3O7-d thin film microbridges with thicknesses between 15 and 50 nm was studied in the optical and terahertz frequency range. The voltage transients in response to short radiation pulses were recorded in real time…
Diffraction-before-destruction imaging with single ultrashort X-ray pulses has the potential to visualise non-equilibrium processes, such as chemical reactions, at the nanoscale with sub-femtosecond resolution in the native environment…
A post-processing adjustment technique which aims for enhancement of dual-frequency SURF (Second order UltRasound Field) reverberation-noise suppression imaging in medical ultrasound is analyzed. Two variant methods are investigated through…
Since the inception of magnetization transfer (MT) imaging, it has been widely assumed that Henkelman's two spin pools have similar longitudinal relaxation times, which motivated many researchers to constrain them to each other. However,…
This paper presents a study of the radiofrequency (RF) characteristics and beam dynamics of an X-band photogun (Xgun) operating in the transient state. The photoinjector is designed to operate with short RF pulses (9 ns) to achieve high…
The following results of dissertation are submitted for defense: 1. Precise measurements of coordinates and proper motion of the pulsar PSR 0329+54 using the VLBI method. 2. Establishing of the reason for the discrepancy between the…