561975 research outputs found
Sort by
Coaxial Dipole Array with Switching Transmit Sensitivities for ultrahigh field MRI
No full textPurpose: To investigate dipole antennas with electronically switchable transmit field patterns to improve flip angle homogeneity in ultra-high field MRI. Methods: Reconfigurable dipole elements that could produce two distinct electronically switchable B+1 field profiles were conceptualized and constructed. Eight such elements were combined into an array. Alteration of the field profiles was accomplished by modulating the currents along the dipoles using a combination of PIN diodes and lumped inductors. The behavior of these reconfigurable elements was studied in numerical electromagnetic simulations and 9.4T MRI measurements, investigating rapid switching of transmit sensitivities during excitation pulses in both single-channel and pTx mode operation. Results: For the simulated dipole elements, modulating the current densities along the dipole's axis causes a ∼ 30% change of the B+1 field between superior and inferior regions of the brain. When rapidly switched during excitation pulses, this degree of freedom can improve flip angle homogeneity, e.g., by a factor of ∼ 2.2 for a two kT points pTx pulse. For the constructed prototype array, the switching effect was observable but weaker, causing ∼ 10% superior-inferior B+1 variation. Conclusions: The proposed coaxial dipole array with switchable transmit sensitivities offers a novel degree of freedom for designing excitation pulses. The approach has the potential to improve flip angle homogeneity without necessitating an expensive increase in the number of independent transmit channels
MMonitor: Software for Real-Time Monitoring of Microbial Communities Using Long Reads
No full textReal-time monitoring of microbial communities offers valuable insights into microbial dynamics across diverse environments. However, many existing metagenome analysis tools require advanced computational expertise and are not designed for monitoring. We present MMonitor, an open-source software platform for real-time analysis and visualization of metagenomic Oxford Nanopore Technologies (ONT) sequencing data. MMonitor includes two components: a desktop application for running bioinformatics pipelines through a graphical user interface (GUI) or command-line interface (CLI) and a web-based dashboard for interactive result inspection. The dashboard provides taxonomic composition over time, quality scores, diversity indices, and taxonomy-metadata correlations. Integrated pipelines enable automated de novo assembly and reconstruction of metagenome-assembled genomes (MAGs). To validate MMonitor, we tracked human gut microbial populations in three bioreactors using 16S rRNA gene sequencing and applied it to whole-genome sequencing (WGS) data to generate high-quality annotated MAGs. We compare MMonitor with other real-time metagenomic tools, outlining their strengths and limitations
Pseudomonas virulence factor SaxA detoxifies plant glucosinolate hydrolysis products, rescuing a commensal that suppresses virulence gene expression
Get PDFLocally imprimitive points on elliptic curves
Get PDFUnder GRH, any element in the multiplicative group of a number field K that is globally primitive (i.e., not a perfect power in K∗) is a primitive root modulo a set of primes of K of positive density. For elliptic curves E/K that are known to have infinitely many primes p of cyclic reduction, possibly under GRH, a globally primitive point P∈E(K) may fail to generate any of the point groups E(kp). We describe this phenomenon in terms of an associated Galois representation ρE/K,P:GK→GL3(Z^), and use it to construct non-trivial examples of global points on elliptic curves that are locally imprimitive
Enhancing thermal stability and mechanical properties in fully-amorphous ZrCu nanolaminates
No full text
Atomic scale configuration of incoherent C36 /C15 phase boundary in an off-stoichiometric Laves phase
No full textPolarization dependence of excess loss of amorphous coating supermirror in optical region for cavity ringdown spectroscopy
No full textA long optical path length is critical in achieving sensitive spectroscopy. For cavity ringdown spectroscopy, a cavity consisting of two supermirrors provides a long path length, where high reflectance of the supermirrors results from their slight excess loss. In the case of a crystal coating supermirror, the excess loss has been suggested to depend on polarization. On the other hand, an amorphous coating supermirror was expected to have a negligible polarization dependence. In this work, we measured the excess loss as a function of mirror rotation around its optical axis in the optical region at 681.2 nm for the three amorphous coating supermirrors produced simultaneously by vapor deposition in the same furnace. The back mirror of the cavity was rotated, and the ringdown time as a function of rotational angle was measured every 10 degrees. As a result, sinusoidal variations in excess loss were observed depending on the rotation. The difference in excess loss between the best and worst rotational angles during the rotation of the back mirror reached a maximum of 5.8 +/- 1.2 ppm. This difference demonstrates the importance of optimizing the rotational angle alignment of supermirrors to achieve high sensitivity via a long path length in cavity ringdown spectroscopy
