A hybrid quantum state is a combination of the Hartle-Hawking state for the physical particles and the Boulware state for the nonphysical ones (such as ghosts), as was introduced in our earlier work [Y. Potaux et al., Phys. Rev. D 105, 025015 (2022).PRVDAQ2470-001010.1103/PhysRevD.105.025015]. We present a two-dimensional example, based on the Russo-Susskind-Thorlacius model, when the corresponding backreacted spacetime is a causal diamond, geodesically complete and free of the curvature singularities. In the static case it shows no presence of the horizon while it has a wormhole structure mimicking the black hole. In the dynamical case, perturbed by a pulse of classical matter, there appears an apparent horizon while the spacetime remains to be a regular causal diamond. We compute the asymptotic radiation both in the static and dynamical case. We define entropy of the asymptotic radiation and demonstrate that as a function of the retarded time it shows the behavior typical for the Page curve. We suggest interpretation of our findings.
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Sensors (Basel)
December 2024
Institute of Communications Engineering, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan.
A core dielectric cylindrical rod wrapped in a dielectric circular pipe whose outer surface is enclosed by a helical conducting strip grating that is skewed along the axial direction is herein analyzed using the asymptotic strip boundary conditions along with classical vector potential analysis. Targeted for use as a cylindrical holographic antenna, the resultant field solutions facilitate the aperture integration of the equivalent cylindrical surface currents to obtain the radiated far fields. As each rod section of a certain skew angle exhibits a distinct modal attribute; this topology allows for the distribution of the cylindrical surface impedance via the effective refractive index to be modulated, as in gradient-index (GRIN) materials.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185, USA.
Magnetic insulation of electrons prevents losses and can be applied to generating radiation or electron sources for high current and high power applications. Ion emission from the anode may degrade magnetic insulation. We develop equilibrium theory, self-consistently coupling magnetically insulated electron flow with free-flowing injected ions.
View Article and Find Full Text PDFJ Acoust Soc Am
December 2024
Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton, Alberta, Canada.
Accurately characterizing bone properties using quantitative ultrasound remains a significant challenge due to the dispersive nature of guided waves, limited observations, irregularity of bone structure, and heterogeneity of bone tissues. In this paper, an inversion technique is proposed that combines weighted mean absolute criteria and the simulated annealing algorithm to extract the thicknesses and elastic properties of a bilayer bone model. By utilizing the L1 norm with an appropriate weighting parameter, this method effectively reduces the influence of outliers and noises commonly encountered in ultrasonic data, leading to more accurate estimation.
View Article and Find Full Text PDFSci Rep
November 2024
Department of Statistics, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami Ku, Hiroshima City, 732-0815, Japan.
In estimating radiation-related risk of cancer and other diseases based on the RERF Life Span Study (LSS), joint analyses can be performed where multiple health outcome endpoints are combined in the same model, allowing some parameters to be estimated in common among all endpoints with possible increase in precision of radiation risk and other model parameter estimates. Using as a basis excess relative risk (ERR) and excess absolute risk (EAR) models of the type commonly used in analysis of LSS data at RERF, we use maximum likelihood theory to compute the asymptotic relative standard error of endpoint-specific radiation effect and other parameter estimates using joint analyses as compared to traditional independent analysis. We show that some gains in precision of endpoint-specific radiation risk parameter estimates can be achieved by sharing effect modifier and other model parameters, but only small or negligible gains in precision are achieved for endpoint-specific background modifying or effect modifying parameters when other model parameters are shared.
View Article and Find Full Text PDFSci Rep
October 2024
Physics Department & Energetic Cosmos Laboratory, Nazarbayev University, 010000, Astana, Qazaqstan, Kazakhstan.
A confined, non-relativistic, accelerating electron is shown to emit thermal radiation. Since laboratories face spatial constraints when dealing with rectilinear motion, focusing on a finite total travel distance combines the benefits of simple theoretical analysis with prospects for table-top experimentation. We demonstrate an accelerated moving charge along an asymptotically static worldline with fixed transit distance and non-relativistic maximum speed, emitting self-consistent analytic power, spectra, and energy.
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