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We present high resolution measurements of the ultrafast temporal dynamics of the critical surface in moderately overdense, hot plasma by using two-color, pump-probe Doppler spectrometry. Our measurements clearly capture the initial inward motion of the plasma inside the critical surface of the pump laser which is followed by outward expansion. The measured instantaneous velocity and acceleration profiles are very well reproduced by a hybrid simulation that uses a 1D electromagnetic particle-in-cell simulation for the initial evolution and a hydrodynamics simulation for the later times. The combination of high temporal resolution and dynamic range in our measurements clearly provides quantitative unraveling of the dynamics in this important region, enabling this as a powerful technique to obtain ultrafast snapshots of plasma density and temperature profiles for providing benchmarks for simulations.
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http://dx.doi.org/10.1103/PhysRevLett.105.105002 | DOI Listing |
J Am Soc Echocardiogr
September 2025
Department of Cardiology, University Hospital of Ghent, Ghent University, Ghent, Belgium.
Background: The shape of the continuous wave Doppler (CWD) envelope in functional tricuspid valve regurgitation (fTR) results from the dynamic interplay between flow, pressure gradient and impedance. Although the v-wave cut-off shape in fTR is a well-recognized feature of severe TR, the complete spectrum of TR CWD shapes across the different fTR severity ranges has not been thoroughly explored, which is the scope of the present study.
Methods: In 245 patients with fTR, TR was graded with transthoracic echocardiography using the corrected proximal isovelocity surface area method and CWD shapes were scored, both qualitatively (using visual scoring into parabolic, triangular or v-wave cut-off categories) and quantitatively using a novel Vmax/Vmean parameter and time-to-peak velocity corrected for TR duration (TTP/TRD).
Nature
September 2025
Department of Physics, University of California, Berkeley, CA, USA.
Trapped-ion applications, such as in quantum information processing, precision measurements, optical clocks and mass spectrometry, rely on specialized high-performance ion traps. The last three of these applications typically use traditional machining to customize macroscopic 3D Paul traps, whereas quantum information processing experiments usually rely on photolithographic techniques to miniaturize the traps and meet scalability requirements. Using photolithography, however, it is challenging to fabricate the complex 3D electrode structures required for optimal confinement.
View Article and Find Full Text PDFPflugers Arch
September 2025
Research Institute for Medicines (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto, 1649-003, Lisbon, Portugal.
Post-occlusive reactive hyperemia (PORH) is a physiological response marked by a transient increase in microvascular perfusion following ischemia. While cutaneous perfusion during PORH has been extensively characterized using optical approaches such as Doppler-based techniques, low-cost alternatives like photoplethysmography (PPG), videocapillaroscopy (VC) and near-infrared reflectance imaging (NIRI) may provide complementary insights into both microvascular and venous dynamics. However, their role in quantifying PORH remains underexplored.
View Article and Find Full Text PDFNMR Biomed
October 2025
High Field MR Center, Department for Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
Dynamic deuterium (H)-MRSI enables mapping of metabolic fluxes in vivo, but its sensitivity is hampered by the low H gyromagnetic ratio and H-labelled metabolite concentrations. Low-rank denoising can enhance MRSI sensitivity by separating signal from noise. Several methods have been proposed, but the optimal approach for dynamic H-MRSI remains unclear.
View Article and Find Full Text PDFAnal Bioanal Chem
August 2025
Institute of Bioanalytics and Agro-Metabolomics, Department of Agricultural Sciences, BOKU University, Konrad-Lorenz-Straße 20, 3430, Tulln, Austria.
Metabolomics, the study of small molecule metabolites in biological systems, is essential for disease diagnosis and biomarker discovery. A key consideration in developing targeted metabolomics methods using HPLC-MS/MS for human or animal plasma is whether to employ derivatization of amino acids, amino acid-related compounds, and biogenic amines. Derivatization with phenyl isothiocyanate (PITC) enhances ionization and LC-separation, but complicates sample preparation and introduces potential errors.
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