Imaging the features of a sample using Positron Annihilation Spectroscopy (PAS) is currently achieved by rastering, i.e. by scanning the sample surface with a sharply focused positron beam. However, a beam of arbitrary shape (sculpted beam) would allow the application of more versatile single-pixel imaging (SPI) techniques. I introduce the design of a microelectronic device employing a 2D array of Zener diodes as an active positron moderator, capable of sculpting positron beams with [Formula: see text] resolution. The re-emitted positrons are accelerated towards the sample through a miniaturized electrostatic lens system and reaching [Formula: see text] resolution. The fast switch-on ([Formula: see text]) and switch-off ([Formula: see text]) time of the device would enable state-of-the-art positron annihilation lifetime spectroscopy (PALS) and PAS imaging with high spatial and temporal resolution.
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http://dx.doi.org/10.1038/s41598-025-89630-9 | DOI Listing |
Philos Trans A Math Phys Eng Sci
March 2025
Department of Statistics, University of Oxford, Oxford, UK.
During infectious disease outbreaks, delays in case reporting mean that the time series of cases is unreliable, particularly for those cases occurring most recently. This means that real-time estimates of the time-varying reproduction number, [Formula: see text], are often made using a time series of cases only up until a time period sufficiently far in the past that there is some confidence in the case counts. This means that the most recent [Formula: see text] estimates are usually out of date, inducing lags in the response of public health authorities.
View Article and Find Full Text PDFPhilos Trans A Math Phys Eng Sci
March 2025
School of Engineering, Computing and Mathematics, Oxford Brooks University, Oxford, UK.
This study introduces an adaptive three-dimensional (3D) image synthesis technique for creating variational realizations of fibrous meniscal tissue microstructures. The method allows controlled deviation from original geometries by modifying parameters such as porosity, pore size and specific surface area of image patches. The unbiased reconstructed samples matched the morphological and hydraulic properties of original tissues, with relative errors generally below 10%.
View Article and Find Full Text PDFSci Rep
March 2025
Department of Materials Science and Engineering, University of North Texas, Denton, TX, 76207, USA.
Direct-write additively manufactured (AM) high-performance lithium titanate (LiTiO) microwave RF ceramic with comparable density, dielectric constant, dielectric loss, and quality factor to traditionally made equivalents is demonstrated. Increasing the surface-to-volume ratio and interfacial free energy in designed electrosteric slurries is shown to be effective for driving pressureless sintering and porosity elimination. A relative density as high as 96.
View Article and Find Full Text PDFSci Rep
March 2025
Department of Laser and Optical Engineering, University of Bonab, Bonab, 5551395133, Iran.
The magneto-optical device based on a periodic array of metal nanopyramids embedded in a film of Bi:YIG coated on the surface of a silver substrate, is optimized utilizing a computational simulation technique (CST Microwave Studio). Under coupling conditions through the two-dimensional grating, the TM-guided modes with narrow resonance are excited in the Bi:YIG film by the incident light, increasing hence the light-matter interaction. Such coupling results as the dips in the reflectance spectrum.
View Article and Find Full Text PDFNat Commun
March 2025
Boulder Research Labs, IMRA America, Inc., 1551 S Sunset St. Suite C, Longmont, CO, USA.
Optical-based terahertz sources are important for many burgeoning scientific and technological applications. Among such applications is precision spectroscopy of molecules, which exhibit rotational transitions at terahertz frequencies. Stemming from precision spectroscopy is frequency discrimination (a core technology in atomic clocks) and stabilization of terahertz sources.
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