Currently, ∼70 % of the occupationally exposed persons in Germany are working in pulsed radiation fields, mainly in the medical sector. It has been known for a few years that active electronic dosemeters exhibit considerable deficits or can even fail completely in pulsed fields. Type test requirements for dosemeters exist only for continuous radiation. Owing to the need of a reference field for pulsed photon radiation and accordingly to the upcoming type test requirements for dosemeters in pulsed radiation, the Physikalisch-Technische Bundesanstalt has developed a novel X-ray reference field for pulsed photon radiation in cooperation with a manufacturer. This reference field, geared to the main applications in the field of medicine, has been well characterised and is now available for research and type testing of dosemeters in pulsed photon radiation.
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http://dx.doi.org/10.1093/rpd/ncs043 | DOI Listing |
Sleep Breath
January 2025
Department of Pulmonary and Critical Care Medicine, Beijing Hospital, National Center of Gerontology, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, No.1 Da Hua Road, Dong Dan, Dongcheng District, Beijing, 100730, PR China.
Purpose: To investigate the relationship between obstructive sleep apnea hypopnea syndrome (OSAHS) severity and fat, bone, and muscle indices.
Methods: This study included 102 patients with OSAHS and retrospectively reviewed their physical examination data. All patients underwent polysomnography, body composition analysis, dual-energy X-ray absorptiometry, computed tomography (CT) and blood test.
Nanotechnology
January 2025
Walker Department of Mechanical Engineering, The University of Texas at Austin, 204 E. Dean Keeton St., Austin, Texas, 78712-1139, UNITED STATES.
Sapphire is an attractive material in photonic, optoelectronic, and transparent ceramic applications that stand to benefit from surface functionalization effects stemming from micro/nanostructures. Here we investigate the use of ultrafast lasers for fabricating nanostructures in sapphire by exploring the relationship between irradiation parameters, morphology change, and selective etching. In this approach an ultrafast laser pulse is focused on the sapphire substrate to change the crystalline morphology to amorphous or polycrystalline, which is characterized by examining different vibrational modes using Raman spectroscopy.
View Article and Find Full Text PDFNat Methods
January 2025
Department of Electrical and Computer Engineering, Boston University, Boston, MA, USA.
Super-resolution imaging of cell metabolism is hindered by the incompatibility of small metabolites with fluorescent dyes and the limited resolution of imaging mass spectrometry. We present ultrasensitive reweighted visible stimulated Raman scattering (URV-SRS), a label-free vibrational imaging technique for multiplexed nanoscopy of intracellular metabolites. We developed a visible SRS microscope with extensive pulse chirping to improve the detection limit to ~4,000 molecules and introduced a self-supervised multi-agent denoiser to suppress non-independent noise in SRS by over 7.
View Article and Find Full Text PDFAn intelligent controlled spatiotemporal mode-locked (STML) fiber laser based on a photonic lantern (PL) is proposed and experimentally demonstrated. A pair of in-house developed PLs is spliced into the cavity in a back-to-back structure. This PL-based structure functions as a mode multiplexer/demultiplexer to generate higher-order spatial modes.
View Article and Find Full Text PDFWe propose and demonstrate a photonic compressive sensing (PCS) scheme for microwave signals using optical pulse random mixing, significantly enhancing both the compression ratio and operating frequency range. Unlike continuous-wave laser-based PCS systems, our approach mitigates the non-ideal characteristics of the pseudo-random binary sequence (PRBS), such as sloped edges and amplitude jitters, resulting in a more ideal compression process. Additionally, the high harmonic components of the optical pulses further facilitate wideband downconversion, improving the system's operating frequency range.
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