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Many questions in physical cosmology regarding the thermal and ionization history of the intergalactic medium are now successfully studied with the help of cosmological hydrodynamical simulations. Here we present a numerical method that…

Astrophysics · Physics 2009-10-31 Tom Abel , Michael L. Norman , Piero Madau

In tomographic reconstruction, the goal is to reconstruct an unknown object from a collection of line integrals. Given a complete sampling of such line integrals for various angles and directions, explicit inverse formulas exist to…

Numerical Analysis · Mathematics 2018-01-18 Tristan van Leeuwen , Simon Maretzke , K. Joost Batenburg

The recent implementation of radiative transfer algorithms in numerous hydrodynamics codes has led to a dramatic improvement in studies of feedback in various astrophysical environments. However, because of methodological limitations and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Jordan Mirocha , Stephen Skory , Jack O. Burns , John H. Wise

Waveform inversion is theoretically a powerful tool to reconstruct subsurface structures, but a usually encountered problem is that accurate sources are very rare, causing the computation unstable and divergent. This challenging problem,…

Geophysics · Physics 2024-07-12 Han Yu

Emission line spectra from HII regions are often used to study properties of the gas in star-forming regions, as well as temperatures and luminosities of the ionising sources. Empirical diagnostics for the interpretation of observational…

Astrophysics · Physics 2007-05-23 Barbara Ercolano , Nate Bastian

3D face reconstruction from a single image is a classical and challenging problem, with wide applications in many areas. Inspired by recent works in face animation from RGB-D or monocular video inputs, we develop a novel method for…

Computer Vision and Pattern Recognition · Computer Science 2018-08-01 Luo Jiang , Juyong Zhang , Bailin Deng , Hao Li , Ligang Liu

How do diffusion generative models convert pure noise into meaningful images? In a variety of pretrained diffusion models (including conditional latent space models like Stable Diffusion), we observe that the reverse diffusion process that…

Computer Vision and Pattern Recognition · Computer Science 2024-03-27 Binxu Wang , John J. Vastola

We propose to use multiphoton interferences of photons emitted from statistically independent thermal light sources in combination with linear optical detection techniques to reconstruct, i.e., image, arbitrary source geometries in one…

In many biological situations, a species arriving from a remote source diffuses in a domain confined between two parallel surfaces until it finds a binding partner. Since such a geometric shape falls in between two- and three-dimensional…

Chemical Physics · Physics 2019-11-05 Denis S. Grebenkov , Diego Krapf

Creating virtual models of real spaces and objects is cumbersome and time consuming. This paper focuses on the problem of geometric reconstruction from sparse data obtained from certain image-based modeling approaches. A number of elegant…

Computational Geometry · Computer Science 2010-03-19 Eleanor G. Rieffel , Don Kimber , Jim Vaughan

We apply the dimensional regularization procedure to treat an ultraviolet divergence occurring in the framework of the nuclear many-body problem. We consider the second--order correction (beyond the mean-field approximation) to the equation…

Nuclear Theory · Physics 2015-06-04 Kassem Moghrabi , Marcella Grasso

One of the most powerful approaches to imaging at the nanometer or subnanometer length scale is coherent diffraction imaging using X-ray sources. For amorphous (non-crystalline) samples, the raw data can be interpreted as the modulus of the…

Numerical Analysis · Mathematics 2020-04-02 Alexander Barnett , Charles L. Epstein , Leslie Greengard , Jeremy Magland

The most important systematical errors in determination of level density and radiative strength functions for deformed nuclei have been estimated from the gamma-ray spectra in nuclear reactions like the stripping or pickup reactions.

The use of fully or partially absorbing boundary conditions for diffusion-based problems has become paradigmatic in physical chemistry and biochemistry to describe reactions occurring in solutions or in living media. However, as chemical…

Statistical Mechanics · Physics 2022-12-13 Francesco Piazza

Some inverse problems in high-energy physics, neutron diffraction and NMR spectroscopy are discussed. To solve them, the Fourier integrated transformation method and the Maximum Entropy Technique (MENT) were used. The integrated images of…

High Energy Physics - Experiment · Physics 2007-05-23 B. Z. Belashev , M. K. Suleymanov

The prediction of cross sections for nuclei far off stability is crucial in the field of nuclear astrophysics. In recent calculations the nuclear level density -- as an important ingredient to the statistical model (Hauser-Feshbach) -- has…

Astrophysics · Physics 2016-08-30 T. Rauscher , F. -K. Thielemann , K. -L. Kratz

Associated Particle Imaging (API) utilizes the inelastic scattering of neutrons produced in deuterium-tritium fusion reactions to obtain 3-D isotopic distributions within an object. The locations of the inelastic scattering centers are…

Instrumentation and Detectors · Physics 2023-10-26 Caroline Egan , Ariel Amsellem , Daniel Klyde , Bernhard Ludewigt , Arun Persaud

We study the three-dimensional (3D) spatially-resolved distribution of the energy density of light in a 3D scattering medium upon the excitation of open transmission channels. The open transmission channels are excited by spatially shaping…

It was recently shown that the phase retrieval imaging of a sample can be modeled as a simple convolution process. Sometimes, such a convolution depends on physical parameters of the sample which are difficult to estimate a priori. In this…

Numerical Analysis · Mathematics 2017-02-20 Eduardo X. Miqueles , Nathaly L. Archilha , Marcelo R. Dos Anjos , Harry Westfahl , Elias S. Helou

Modern technology for producing extremely bright and coherent X-ray laser pulses provides the possibility to acquire a large number of diffraction patterns from individual biological nanoparticles, including proteins, viruses, and DNA.…

Methodology · Statistics 2018-07-11 Stefan Engblom , Carl Nettelblad , Jing Liu
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