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In this paper, we provide a novel method for the estimation of unknown parameters of the Gaussian Mixture Model (GMM) in Positron Emission Tomography (PET). A vast majority of PET imaging methods are based on reconstruction model that is…

Signal Processing · Electrical Eng. & Systems 2023-06-30 Tomislav Matulić , Damir Seršić

We present the first application of the isosceles bispectrum to MCMC parameter inference from the cosmic 21-cm signal. We extend the MCMC sampler 21cmMC to use the fast bispectrum code, BiFFT, when computing the likelihood. We create mock…

Cosmology and Nongalactic Astrophysics · Physics 2022-01-19 Catherine A. Watkinson , Bradley Greig , Andrei Mesinger

Gaussian process (GP) predictors are an important component of many Bayesian approaches to machine learning. However, even a straightforward implementation of Gaussian process regression (GPR) requires O(n^2) space and O(n^3) time for a…

Machine Learning · Statistics 2012-11-06 Krzysztof Chalupka , Christopher K. I. Williams , Iain Murray

Gaussian process (GP) models are widely used to emulate propagation uncertainty in computer experiments. GP emulation sits comfortably within an analytically tractable Bayesian framework. Apart from propagating uncertainty of the input…

Methodology · Statistics 2015-01-30 Silvia Montagna , Surya T. Tokdar

We present GPR_calculator, a package based on Python and C++ programming languages to build an on-the-fly surrogate model using Gaussian Process Regression (GPR) to approximate expensive electronic structure calculations. The key idea is to…

Materials Science · Physics 2026-01-30 Isaac Onyango , Byungkyun Kang , Qiang Zhu

The first measurements of the 21 cm brightness temperature power spectrum from the epoch of reionization will very likely be achieved in the near future by radio interferometric array experiments such as the Hydrogen Epoch of Reionization…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-22 Xiaosheng Zhao , Yi Mao , Benjamin D. Wandelt

Folding uncertainty in theoretical models into Bayesian parameter estimation is necessary in order to make reliable inferences. A general means of achieving this is by marginalizing over model uncertainty using a prior distribution…

General Relativity and Quantum Cosmology · Physics 2016-03-04 Christopher J. Moore , Christopher P. L. Berry , Alvin J. K. Chua , Jonathan R. Gair

With a statistical detection of the 21 cm signal fluctuations from the Epoch of Reionization (EoR) expected in the next few years, there is an interest in developing robust and precise techniques to constrain the underlying astrophysical…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Evan Eames , Aristide Doussot , Benoît Semelin

Tomographic three-dimensional 21 cm images from the epoch of reionization contain a wealth of information about the reionization of the intergalactic medium by astrophysical sources. Conventional power spectrum analysis cannot exploit the…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-22 Xiaosheng Zhao , Yi Mao , Cheng Cheng , Benjamin D. Wandelt

Bayesian parameter inference is one of the key elements for model selection in cosmological research. However, the available inference tools require a large number of calls to simulation codes which can lead to high and sometimes even…

Cosmology and Nongalactic Astrophysics · Physics 2024-06-10 Sven Günther

In this paper we propose a novel Bayesian solution for nonlinear regression in complex fields. Previous solutions for kernels methods usually assume a complexification approach, where the real-valued kernel is replaced by a complex-valued…

Machine Learning · Computer Science 2018-03-02 Rafael Boloix-Tortosa , Eva Arias-de-Reyna , F. Javier Payan-Somet , Juan J. Murillo-Fuentes

Neural network (NN) emulators of the global 21 cm signal need emulation error much less than the observational noise in order to be used to perform unbiased Bayesian parameter inference. To this end, we introduce $\texttt{21cmLSTM}$ -- a…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-11 J. Dorigo Jones , S. M. Bahauddin , D. Rapetti , J. Mirocha , J. O. Burns

We compare the predictions of four different algorithms for the distribution of ionized gas during the Epoch of Reionization. These algorithms are all used to run a 100 Mpc/h simulation of reionization with the same initial conditions. Two…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 Oliver Zahn , Andrei Mesinger , Matthew McQuinn , Hy Trac , Renyue Cen , Lars E. Hernquist

We develop a computational procedure to estimate the covariance hyperparameters for semiparametric Gaussian process regression models with additive noise. Namely, the presented method can be used to efficiently estimate the variance of the…

Machine Learning · Computer Science 2022-06-22 Siavash Ameli , Shawn C. Shadden

Gaussian Process Regression (GPR) is a powerful and elegant method for learning complex functions from noisy data with a wide range of applications, including in safety-critical domains. Such applications have two key features: (i) they…

Machine Learning · Computer Science 2024-12-23 Robert Reed , Luca Laurenti , Morteza Lahijanian

Semi-analytic models are a powerful tool for studying the formation of galaxies. However, these models inevitably involve a significant number of poorly constrained parameters that must be adjusted to provide an acceptable match to the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-18 R. G. Bower , I. Vernon , M. Goldstein , A. J. Benson , C. G. Lacey , C. M. Baugh , S. Cole , C. S. Frenk , .

The high redshift 21-cm signal promises to be a crucial probe of the state of the intergalactic medium (IGM). Understanding the connection between the observed 21-cm power spectrum and the physical quantities intricately associated with the…

To accurately reproduce measurements from the real world, simulators need to have an adequate model of the physical system and require the parameters of the model be identified. We address the latter problem of estimating parameters through…

Robotics · Computer Science 2022-03-01 Eric Heiden , Christopher E. Denniston , David Millard , Fabio Ramos , Gaurav S. Sukhatme

This paper explores the application of kernel learning methods for parameter prediction and evaluation in the Algebraic Multigrid Method (AMG), focusing on several Partial Differential Equation (PDE) problems. AMG is an efficient iterative…

Numerical Analysis · Mathematics 2025-10-31 Junyue Luo , Xiaoqiang Yue , Fangfang Zhang , Juan Zhang

Gaussian Mixture Models (GMMs) range among the most frequently used models in machine learning. However, training large, general GMMs becomes computationally prohibitive for datasets that have many data points $N$ of high-dimensionality…

Machine Learning · Statistics 2025-12-12 Sebastian Salwig , Till Kahlke , Florian Hirschberger , Dennis Forster , Jörg Lücke