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We apply a recently developed framework for analyzing the convergence of stochastic algorithms to the general problem of large-scale nonconvex composite optimization more generally, and nonconvex likelihood maximization in particular. Our…

Optimization and Control · Mathematics 2024-01-25 D. Russell Luke , Steffen Schultze , Helmut Grubmüller

Numerical simulation codes are very common tools to study complex phenomena, but they are often time-consuming and considered as black boxes. For some statistical studies (e.g. asset management, sensitivity analysis) or optimization…

Statistics Theory · Mathematics 2017-08-14 Vincent Moutoussamy , Simon Nanty , Benoît Pauwels

In the new precision era for cosmic ray astrophysics, theoretical predictions cannot content themselves with average trends, but need to correctly take into account intrinsic uncertainties. The space-time discreteness of the cosmic ray…

High Energy Astrophysical Phenomena · Physics 2017-04-05 Yoann Genolini , Pierre Salati , Pasquale Serpico , Richard Taillet

We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray (CR) origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron…

Astrophysics · Physics 2009-10-31 I. V. Moskalenko , A. W. Strong

Cosmic-ray transport in astrophysical environments is often dominated by the diffusion of particles in a magnetic field composed of both a turbulent and a mean component. This process, which is two-fold turbulent mixing in that the particle…

High Energy Astrophysical Phenomena · Physics 2021-12-14 P. Reichherzer , L. Merten , J. Dörner , J. Becker Tjus , M. J. Pueschel , E. G. Zweibel

Stochastic economic dispatch models address uncertainties in forecasts of renewable generation output by considering a finite number of realizations drawn from a stochastic process model, typically via Monte Carlo sampling. Accurate…

Computational Engineering, Finance, and Science · Computer Science 2015-08-24 Cosmin Safta , Richard L. -Y. Chen , Habib N. Najm , Ali Pinar , Jean-Paul Watson

Recently, learned image compression has attracted considerable attention due to its superior performance over traditional methods. However, most existing approaches employ a single entropy model to estimate the probability distribution of…

Computer Vision and Pattern Recognition · Computer Science 2026-03-31 Chunhang Zheng , Zichang Ren , Dou Li

Several cosmological measurements have attained significant levels of maturity and accuracy over the last decade. Continuing this trend, future observations promise measurements of the statistics of the cosmic mass distribution at an…

Astrophysics · Physics 2008-11-26 Salman Habib , Katrin Heitmann , David Higdon , Charles Nakhleh , Brian Williams

In order to increase the efficiency of the computer simulation of biological molecules, it is very common to impose holonomic constraints on the fastest degrees of freedom; normally bond lengths, but also possibly bond angles. However, as…

Chemical Physics · Physics 2011-12-19 Pablo Echenique , Claudio N. Cavasotto , Pablo García-Risueño

We present a new parametrization of the cosmic-ray flux and its mass composition over an energy range from 10 GeV to $10^{11}$ GeV. Our approach is data-driven and relies on theoretical assumptions as little as possible. We combine…

High Energy Astrophysical Phenomena · Physics 2017-12-01 Hans Dembinski , Ralph Engel , Anatoli Fedynitch , Thomas Gaisser , Felix Riehn , Todor Stanev

The observations of the total electronic component and the positron fraction in cosmic rays by the FERMI, HESS, ATIC, and PAMELA instruments are studied with analytical propagation models, both for a set of discrete sources and for a…

Cosmology and Nongalactic Astrophysics · Physics 2009-06-15 R. Cowsik , B. Burch

Accurate prediction of the radio emission from cosmic ray air showers relies on computationally demanding Monte Carlo simulations such as CoREAS. We aim to expedite this process via a semi-analytical synthesis model while maintaining high…

High Energy Astrophysical Phenomena · Physics 2019-08-27 David Butler , Tim Huege , Ralph Engel , Olaf Scholten

The unprecedented quality of the data collected by the AMS-02 experiment onboard the International Space Station allowed us to address subtle questions concerning the origin and propagation of cosmic rays. Here we discuss the implications…

High Energy Astrophysical Phenomena · Physics 2019-06-05 Carmelo Evoli , Roberto Aloisio , Pasquale Blasi

This work introduces two Monte Carlo (MC)-based sampling methods, known as line sampling and subset simulation, to improve the performance of standard MC analyses in the context of asteroid impact risk assessment. Both techniques sample the…

Earth and Planetary Astrophysics · Physics 2020-09-28 Matteo Romano , Matteo Losacco , Camilla Colombo , Pierluigi Di Lizia

Observations of diffuse radio emission in galaxy clusters indicate that cosmic-ray electrons are accelerated on $\sim$Mpc scales. However, protons appear to be accelerated less efficiently since their associated hadronic $\gamma$-ray…

High Energy Astrophysical Phenomena · Physics 2016-12-14 Denis Wittor , Franco Vazza , Marcus Brüggen

Aims. Numerical test-particle simulations are a reliable and frequently used tool to test analytical transport theories and to predict mean-free paths. The comparison between solutions of the diffusion equation and the particle flux is used…

High Energy Astrophysical Phenomena · Physics 2016-02-17 R. C. Tautz , J. Bolte , A. Shalchi

Electron capture (EC) isotopes are known to provide constraints on the low energy behavior of cosmic rays (CRs), such as re-acceleration. Here we study the EC isotopes within the framework of the dynamic spiral-arms CR propagation model in…

High Energy Astrophysical Phenomena · Physics 2017-12-27 David Benyamin , Nir J. Shaviv , Tsvi Piran

The spatial distribution of cosmic ray (CR) particles in the interstellar medium (ISM) is of major importance in radio astronomy, where its knowledge is essential for the interpretation of observations, and in theoretical astrophysics,…

Astrophysics of Galaxies · Physics 2023-06-28 Devika Tharakkal , Andrew P. Snodin , Graeme R. Sarson , Anvar Shukurov

We derive explicit, algebraic expressions for the steady-state number density of cosmic ray electrons as a function of position and energy using Green's function of the diffusion equation with energy losses for an axisymmetric distributions…

Astrophysics of Galaxies · Physics 2026-04-28 Anvar Shukurov , Charles Jose

Much scientific work has focused on the generation of random numbers as well as the distribution of said random numbers for use as a cryptographic key. However, emphasis is often placed on one of the two to the exclusion of the other, but…

Classical Physics · Physics 2020-08-14 Nicholas Bornman , Andrew Forbes , Achim Kempf