With exact three-flavor Boltzmann neutrino transport, we simulate the stellar core collapse, bounce, and postbounce evolution of a 13M star in spherical symmetry, the Newtonian limit, without invoking convection. In the absence of convection, prior spherically symmetric models, which implemented approximations to Boltzmann transport, failed to produce explosions. We consider exact transport to determine if these failures were due to the transport approximations made and to answer remaining fundamental questions in supernova theory. The model presented here is the first in a sequence of models beginning with different progenitors. In this model, a supernova explosion is not obtained.
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http://dx.doi.org/10.1103/PhysRevLett.86.1935 | DOI Listing |
Phys Rev Lett
December 2024
Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland.
We performed the first simulations of accretion onto the compact objects in the Reissner-Nordström (RN) space-time. The results obtained in general relativity are representative of those for spherically symmetric naked singularities and black holes in a number of modified gravity theories. A possible application of these calculations is to the active galactic nuclei with their powerful jets and outflows.
View Article and Find Full Text PDFMed Phys
December 2024
Department of Physics, Lakehead University, Thunder Bay, Ontario, Canada.
Background: This study investigates a multi-angle acquisition method aimed at improving image quality in organ-targeted PET detectors with planar detector heads. Organ-targeted PET technologies have emerged to address limitations of conventional whole-body PET/CT systems, such as restricted axial field-of-view (AFOV), limited spatial resolution, and high radiation exposure associated with PET procedures. The AFOV in organ-targeted PET can be adjusted to the organ of interest, minimizing unwanted signals from other parts of the body, thus improving signal collection efficiency and reducing the dose of administered radiotracer.
View Article and Find Full Text PDFACS Sens
December 2024
York Plasma Institute, School of Physics, Engineering and Technology, University of York, York YO10 5DD, U.K.
Nanogold is an emerging material for enhancing surface-enhanced Raman scattering (SERS), which enables the detection of hazardous analytes at trace levels. This study presents a simple, single-step plasma synthesis method to control the size and yield of Au nanoparticles by using plasma-liquid redox chemistry. The pin-based argon plasma reduces the Au precursor in under 5 min, synthesizing Au spherical particles ranging from ∼20 nm at 0.
View Article and Find Full Text PDFBMC Ophthalmol
December 2024
Ophthalmology Department, Faculty of Medicine, Sohag University, Almohafza St. Mailbox: 82511, Sohag, 82511, Egypt.
Purpose: To evaluate the clinical outcomes of implanting two symmetrical Kerarings via a femtosecond laser in grade three keratoconus.
Patients And Methods: This was a retrospective nonrandomized controlled clinical study. The study included one eye from each of twenty-three patients, all with Grade 3 keratoconus as classified by the Amsler-Krumeich classification.
Nano Lett
December 2024
KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea.
Over the last three decades, colloidal crystallization has provided an easy-to-craft platform for mesoscale engineering of photonic and phononic crystals. Nevertheless, the crystal lattices achieved thus far with commodity colloids are largely limited to symmetric and densely packed structures, restricting their functionalities. To obtain non-close-packed crystals and the resulting complexity of the available structures, directional binding between "patchy" colloids has been pursued.
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