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http://dx.doi.org/10.21037/jtd.2017.06.72 | DOI Listing |
Phys Rev Lett
December 2024
Universität Heidelberg, Kirchhoff-Institut für Physik, Im Neuenheimer Feld 227, 69120 Heidelberg, Germany.
We experimentally study cosmological particle production in a two-dimensional Bose-Einstein condensate, whose density excitations map to an analog cosmology. The expansion of spacetime is realized with tunable interactions. The particle spectrum can be understood through an analogy to quantum mechanical scattering, in which the dynamics of the spacetime metric determine the shape of the scattering potential.
View Article and Find Full Text PDFDue to mode coupling, a high signal-to-noise ratio (SNR) is required in orbital angular momentum (OAM) modular division multiplexing (MDM) systems to improve transmission performance. In this paper, a cascade delta-sigma modulation (CDSM) scheme is proposed for OAM-MDM intensity modulation and direct detection (IM/DD) transmission. Different from the traditional DSM (TDSM) scheme, the scheme is divided into signal modulation and in-band noise modulation, in which the in-band noise modulation is used to further decrease the quantization noise generated in the signal modulation.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia.
This study investigates the motion of an electron in a Coulomb potential driven by an intense linearly polarized XUV laser pulse analyzed using Gordon-Volkov wave functions. The wave function is decomposed into spherical partial waves to model the scattered electron wave packet after the recollision with a proton. This interaction triggers high harmonic generation, producing coherent X-ray pulses with frequencies that are integer multiples of the XUV field.
View Article and Find Full Text PDFJ Cardiovasc Magn Reson
January 2025
Department of Radiology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA. Electronic address:
Background: Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) shows promise for quantifying mitral regurgitation (MR) by allowing for direct regurgitant volume (RVol) measurement using a plane precisely placed at the MR jet. However, the ideal location of a measurement plane remains unclear. This study aims to systematically examine how varying measurement locations affect RVol quantification and determine the optimal location using the momentum conservation principle of a free jet.
View Article and Find Full Text PDFJ Biomech
January 2025
Stevens Institute of Technology, Hoboken, NJ, USA. Electronic address:
This study revealed how high school pitchers generated momenta during fastballs and changeups at a whole-body level. Baseball pitchers control ground reaction forces to generate whole-body momentum. Pitchers attempt to throw as fast and accurately as possible during fastballs but also need to throw off-speed pitches like changeups to deceive batters.
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