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Thanks to space-borne experiments of cosmic-ray (CR) detection, such as the AMS and PAMELA missions in low-Earth orbit, or the Voyager-1 spacecraft in the interstellar space, a large collection of multi-channel and time-resolved CR data has…

High Energy Astrophysical Phenomena · Physics 2019-07-01 Nicola Tomassetti , Fernando Barão , Bruna Bertucci , Emanuele Fiandrini , Miguel Orcinha

We extend the diffusion-map formalism to data sets that are induced by asymmetric kernels. Analytical convergence results of the resulting expansion are proved, and an algorithm is proposed to perform the dimensional reduction. In this work…

Machine Learning · Computer Science 2024-01-24 Alvaro Almeida Gomez , Antonio Silva Neto , Jorge zubelli

In time-distance helioseismology, information about the solar interior is encoded in measurements of travel times between pairs of points on the solar surface. Travel times are deduced from the cross-covariance of the random wave field.…

Solar and Stellar Astrophysics · Physics 2014-09-05 Damien Fournier , Laurent Gizon , Thorsten Hohage , Aaron C. Birch

Context. The frequencies, lifetimes, and eigenfunctions of solar acoustic waves are affected by turbulent convection, which is random in space and in time. Since the correlation time of solar granulation and the periods of acoustic waves…

Solar and Stellar Astrophysics · Physics 2020-11-25 P. -L. Poulier , D. Fournier , L. Gizon , T. L. Duvall

Millimter (mm) frequencies are primarily sensitive to thermal emission from layers across the stellar chromosphere up to the transition region, while metrewave (radio) frequencies probe the coronal heights. Together the mm and radio band…

Solar and Stellar Astrophysics · Physics 2025-10-16 Atul Mohan

Time-distance helioseismology is the method of the study of the propagation of waves through the solar interior via the travel times of those waves. The travel times of wave packets contain information about the conditions in the interior…

Solar and Stellar Astrophysics · Physics 2019-02-20 David Korda , Michal Švanda

Selecting an appropriate kernel is a central challenge in kernel-based spectral methods. In \emph{Kernelized Diffusion Maps} (KDM), the kernel determines the accuracy of the RKHS estimator of a diffusion-type operator and hence the quality…

Machine Learning · Statistics 2026-04-21 Othmane Aboussaad , Adam Miraoui , Boumediene Hamzi , Houman Owhadi

Kernel theorems, in general, provide a convenient representation of bounded linear operators. For the operator acting on a concrete function space, this means that its action on any element of the space can be expressed as a generalised…

Functional Analysis · Mathematics 2024-05-22 Dimitri Bytchenkoff , Michael Speckbacher , Peter Balazs

Optimal frequency identification in astronomical datasets is crucial for variable star studies, exoplanet detection, and asteroseismology. Traditional period-finding methods often rely on specific parametric assumptions, employ binning…

Instrumentation and Methods for Astrophysics · Physics 2024-06-12 F. Stoppa , C. Johnston , E. Cator , G. Nelemans , P. J. Groot

Kernel smoothing is a highly flexible and popular approach for estimation of probability density and intensity functions of continuous spatial data. In this role it also forms an integral part of estimation of functionals such as the…

Methodology · Statistics 2017-07-24 Tilman M. Davies , Jonathan C. Marshall , Martin L. Hazelton

Anomalous heat transport observed in low dimensional classical systems is associated to super-diffusive spreading of space-time correlation of the conserved fields in the system. This leads to non-local linear response relation between the…

Statistical Mechanics · Physics 2023-09-29 Anupam Kundu

We use a support vector regressor based on a projected quantum kernel method to predict the density structure of 1D fermionic systems of interest in quantum chemistry and quantum matter. The kernel is built on with the observables of a…

Quantum Physics · Physics 2025-09-01 Francesco Perciavalle , Francesco Plastina , Michele Pisarra , Nicola Lo Gullo

Using a high cadence imaging spectropolarimetric observation of a sunspot and its surroundings in magnetically sensitive (FeI 6173 A) and insensitive (FeI 7090 A) upper photospheric absorption lines, we map the instantaneous wave phases and…

Solar and Stellar Astrophysics · Physics 2010-09-14 S. P. Rajaguru , R. Wachter , K. Sankarasubramanian , S. Couvidat

In this paper we investigate the long-time behavior of the subordination of the constant speed traveling waves by a general class of kernels. We use the Feller--Karamata Tauberian theorem in order to study the long-time behavior of the…

Probability · Mathematics 2021-04-02 Yuri Kondratiev , José Luís da Silva

Using a fully Bayesian approach, Gaussian Process regression is extended to include marginalisation over the kernel choice and kernel hyperparameters. In addition, Bayesian model comparison via the evidence enables direct kernel comparison.…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-13 Namu Kroupa , David Yallup , Will Handley , Michael Hobson

Extreme-ultraviolet and X-ray jets occur frequently in magnetically open coronal holes on the Sun, especially at high solar latitudes. Some of these jets are observed by white-light coronagraphs as they propagate through the outer corona…

Solar and Stellar Astrophysics · Physics 2017-03-15 Vadim M. Uritsky , Merrill A. Roberts , C. Richard DeVore , Judith T. Karpen

It is well known that the observed amplitude of solar oscillations is lower in sunspots than in quiet regions of the Sun. We show that this local reduction in oscillation amplitudes combined with the phase-speed filtering procedure in…

Astrophysics · Physics 2009-11-11 S. P. Rajaguru , A. C. Birch , T. L. Duvall , M. J. Thompson , J. Zhao

Flare ribbons form when energy released by coronal magnetic reconnection is deposited in the low solar atmosphere, so by studying the dynamics of flare ribbons, one obtains an indirect measurement of reconnection. Our aim is to quantify the…

Solar and Stellar Astrophysics · Physics 2026-05-13 Hannah Collier , Säm Krucker , Laura A. Hayes , Emil Kraaikamp , David Berghmans , Daniel F. Ryan

About 1/3 of X-ray-luminous clusters show smooth, Mpc-scale radio emission, known as giant radio haloes. One promising model for radio haloes is Fermi-II acceleration of seed relativistic electrons by compressible turbulence. The origin of…

High Energy Astrophysical Phenomena · Physics 2017-01-11 Anders Pinzke , S. Peng Oh , Christoph Pfrommer

This article presents a general framework for the transport of probability measures towards minimum divergence generative modeling and sampling using ordinary differential equations (ODEs) and Reproducing Kernel Hilbert Spaces (RKHSs),…

Machine Learning · Statistics 2024-02-14 Biraj Pandey , Bamdad Hosseini , Pau Batlle , Houman Owhadi
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