Ergodic encoding for single-element ultrasound imaging in vivo

Conventional ultrasound imaging relies on the computation of geometric time delay from multiple sensors to detect the position of a scatterer. In this paper, we present Ergodic Relay Ultrasound Imaging (ERUI), a method that utilizes an ergodic cavity down to a single ultrasonic sensor for ultrasound imaging. With the proposed method, the ergodic cavity creates a unique temporal signature that encodes the position of a scatterer. When compared to standard approaches, ERUI enables the generation of images of comparable quality while utilizing fewer detector elements. Our results suggest that ERUI has the potential to achieve image resolution similar to that of traditional imaging techniques, shifting the complexity from hardware to sofware. The demonstrated feasibility offers a promising path towards ultrasound probes with reduced costs and complexity for more portable scanning devices.Comment: 5 pages, 4 figures, Lette

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements