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Complex physical systems, from supersonic turbulence to the macroscopic structure of the universe, are governed by continuous multiscale dynamics. While modern machine learning architectures excel at mapping the high-dimensional observables…

Machine Learning · Computer Science 2026-05-04 Mengke Zhao , Guang-Xing Li , Duo Xu , Keping Qiu

Here we introduce the Delaunay Density Estimator Method. Its purpose is rendering a fully volume-covering reconstruction of a density field from a set of discrete data points sampling this field. Reconstructing density or intensity fields…

Astrophysics · Physics 2007-05-23 W. E. Schaap , R. van de Weygaert

Aims. We study the effect of large scale dynamics on the molecular composition of the dense interstellar medium during the transition between diffuse to dense clouds. Methods. We followed the formation of dense clouds (on sub-parsec scales)…

Astrophysics of Galaxies · Physics 2018-04-11 M. Ruaud , V. Wakelam , P. Gratier , I. A. Bonnell

The large-scale structure in cosmology is highly non-Gaussian at late times and small length scales, making it difficult to describe analytically. Parameter inference, data reconstruction, and data generation tasks in cosmology are greatly…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-13 Adam Rouhiainen

The Local Universe (D < 120 Mpc) has been intensely studied for decades, with highly complete galaxy redshift surveys now publicly available. These data have driven density reconstructions of the underlying matter density field, as well as…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-22 Yuxin Huang , Khee-Gan Lee , Noam I. Libeskind , Sunil Simha , Aurélien Valade , J. Xavier Prochaska

We propose a new, efficient multi-scale method to decompose a map (or signal in general) into components maps that contain structures of different sizes. In the widely-used wave transform, artifacts containing negative values arise around…

Instrumentation and Methods for Astrophysics · Physics 2022-04-11 Guang-Xing Li

The cloud-scale density, velocity dispersion, and gravitational boundedness of the interstellar medium (ISM) vary within and among galaxies. In turbulent models, these properties play key roles in the ability of gas to form stars. New high…

Ultraviolet and optical spectra of interstellar gas along the lines of sight to nearby stars have been interpreted by Redfield & Linsky (2008) and previous studies as a set of discrete warm, partially ionized clouds each with a different…

Astrophysics of Galaxies · Physics 2015-10-21 Seth Redfield , Jeffrey L. Linsky

Accurately measuring magnetic field strength in the interstellar medium, including giant molecular clouds (GMCs), remains a significant challenge. We present a machine learning approach using Denoising Diffusion Probabilistic Models (DDPMs)…

Astrophysics of Galaxies · Physics 2025-01-09 Duo Xu , Jenna Karcheski , Chi-Yan Law , Ye Zhu , Chia-Jung Hsu , Jonathan C. Tan

One of the fundamental problems in machine learning is the estimation of a probability distribution from data. Many techniques have been proposed to study the structure of data, most often building around the assumption that observations…

Machine Learning · Statistics 2013-02-22 Oren Rippel , Ryan Prescott Adams

Molecular clouds (MC) are structures of dense gas in the interstellar medium (ISM), that extend from ten to a few hundred parsecs and form the main gas reservoir available for star formation. Hydrodynamical simulations of varying complexity…

Many recent models consider the structure of individual interstellar medium (ISM) clouds as a way to explain observations of large parts of galaxies. To compare such models to observations, one must understand how to translate between…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Adam K. Leroy , Cheoljong Lee , Andreas Schruba , Alberto Bolatto , Annie Hughes , Jerome Pety , Karin Sandstrom , Eva Schinnerer , Fabian Walter

Diffusion models are at the vanguard of generative AI research with renowned solutions such as ImageGen by Google Brain and DALL.E 3 by OpenAI. Nevertheless, the potential merits of diffusion models for communication engineering…

Information Theory · Computer Science 2023-11-17 Mehdi Letafati , Samad Ali , Matti Latva-aho

We have constructed three-dimensional models for the equilibrium abundance of molecular hydrogen within diffuse interstellar clouds of arbitrary geometry that are illuminated by ultraviolet radiation. The position-dependent photo-…

Astrophysics · Physics 2009-10-30 Marco Spaans , David A. Neufeld

Given the widespread availability of grids of models for stellar atmospheres, it is necessary to recover intermediate atmospheric models by means of accurate techniques that go beyond simple linear interpolation and capture the intricacies…

Instrumentation and Methods for Astrophysics · Physics 2023-07-26 C. Westendorp Plaza , A. Asensio Ramos , C. Allende Prieto

High-resolution JWST-MIRI images now allow us to resolve in great detail the multi-scale nature of the emission in nearby star-forming galaxies, from compact star-forming regions to large-scale diffuse emission, giving new insights into…

We present an ``equation-free'' multiscale approach to the simulation of unsteady diffusion in a random medium. The diffusivity of the medium is modeled as a random field with short correlation length, and the governing equations are cast…

Numerical Analysis · Mathematics 2007-05-23 Dongbin Xiu , Ioannis Kevrekidis

Point cloud streaming is increasingly getting popular, evolving into the norm for interactive service delivery and the future Metaverse. However, the substantial volume of data associated with point clouds presents numerous challenges,…

Computer Vision and Pattern Recognition · Computer Science 2024-08-16 Yanlong Li , Chamara Madarasingha , Kanchana Thilakarathna

Mutual information (MI) is one of the most general ways to measure relationships between random variables, but estimating this quantity for complex systems is challenging. Denoising diffusion models have recently set a new bar for density…

Machine Learning · Computer Science 2025-11-20 Longxuan Yu , Xing Shi , Xianghao Kong , Tong Jia , Greg Ver Steeg

We propose a simple analytical method for estimating the central volume density of prestellar molecular cloud cores from their column density profiles. Prestellar cores feature a flat central part of the column density and volume density…

Astrophysics of Galaxies · Physics 2015-05-28 Konstantinos Tassis , Harold W. Yorke