March 9th, 2021

лошадь, диаграмма, Фейнман

Самодельное МРТ в домашних условиях???

A Fast 0.5T Prepolarizer Module for Preclinical Magnetic Resonance Imaging:
J.P. Rigla, J. Borreguero, C. Gramage, E. Pallás, J.M. González, R. Bosch, J.M. Algarín, J.V. Sanchez-Andres, F. Galve, D. Grau-Ruiz, R. Pellicer, A. Ríos, J.M. Benlloch, J. Alonso
We present a magnet and high power electronics for Prepolarized Magnetic Resonance Imaging (PMRI) in a home-made, special-purpose preclinical system designed for simultaneous visualization of hard and soft biological tissues. PMRI boosts the signal-to-noise ratio (SNR) by means of a long and strong magnetic pulse which must be rapidly switched off prior to the imaging pulse sequence, in timescales shorter than the spin relaxation (or T1) time of the sample. We have operated the prepolarizer at up to 0.5 T and demonstrated enhanced magnetization, image SNR and tissue contrast with PMRI of tap water, an ex vivo mouse brain and food samples. These have T1 times ranging from hundreds of milli-seconds to single seconds, while the preliminary high-power electronics setup employed in this work can switch off the prepolarization field in tens of milli-seconds. In order to make this system suitable for solid-state matter and hard tissues, which feature T1 times as short as 10 ms, we are developing new electronics which can cut switching times to ~300 us. This does not require changes in the prepolarizer module, opening the door to the first experimental demonstration of PMRI on hard biological tissues.
Comments: 8 pages, 10 figures, 2 tables, comments welcome
лошадь, диаграмма, Фейнман

Бразильцы продолжают...

Particle Physics in High School Part I: Quantum Electrodynamics:
Glauber Carvalho Dorsch, Thaisa Carneiro da Cunha Guio
This is the first paper of a series aiming to present a new teaching sequence for Particle Physics in high school. We propose a systematic discussion of the subject, covering not only the understanding of its key concepts, but also of the very nature of Science, of the factors that surround its practice and of its relations to technology, society and the environment, in a framework towards scientific literacy. In this work we present the first part of this teaching sequence, focused on the quantum theory of electromagnetism: Quantum Electrodynamics. We analyze the potentialities of the material proposed here, when applied in a dialogic manner by the teacher, by evaluating the presence of scientific literacy and engagement indicators throughout interventions at a full-time public school in Espirito Santo, Brazil.
Comments: 32 figures, in Portuguese