Filters








62,069 Hits in 3.5 sec

Understanding and Accelerating Particle-Based Variational Inference [article]

Chang Liu, Jingwei Zhuo, Pengyu Cheng, Ruiyi Zhang, Jun Zhu, Lawrence Carin
2019 arXiv   pre-print
Particle-based variational inference methods (ParVIs) have gained attention in the Bayesian inference literature, for their capacity to yield flexible and accurate approximations.  ...  We propose an acceleration framework and a principled bandwidth-selection method for general ParVIs; these are based on the developed theory and leverage the geometry of the Wasserstein space.  ...  Recently, particle-based variational inference methods (ParVIs) have been proposed.  ... 
arXiv:1807.01750v4 fatcat:zm73eyeyo5fvxic33qiq6a4i7e

Quarks and the Cosmos

Michael S. Turner
2013 Quest for the Origin of Particles and the Universe  
Quarks and the Cosmos www.sciencemag.org (this information is current as of January 28, 2008 ): The following resources related to this article are available online at  ...  Speculations about the earliest moments of creation and possible answers to all the big questions, based on bold ideas about how the fundamental particles and forces of nature are unified, burst forth.  ...  [Image: NASA/WMAP Science Team] Because the scientific agendas of cosmology and particle physics have converged, as we deepen our understanding of the universe, we will advance our understanding of the  ... 
doi:10.1142/9789814412322_0010 fatcat:cdisquvdsbae3mlxhnypzef5ou

High-Energy Polarimetry - a new window to probe extreme physics in AGN jets [article]

B. Rani, H. Zhang, S. D. Hunter, F. Kislat, M. Böttcher, J. E. McEnery, D. J. Thompson, D. Giannios, F. Guo, H. Li, M. Baring, I. Agudo (+20 others)
2019 arXiv   pre-print
The constantly improving sensitivity of ground-based and space-borne observatories has made possible the detection of high-energy emission (X-rays and gamma-rays) from several thousands of extragalactic  ...  Enormous progress has been made in measuring the continuum flux enabling us to perform imaging, spectral and timing studies.  ...  , we need to achieve a through physical understanding of the plasma jet dynamics, particle acceleration, and radiation processes.  ... 
arXiv:1903.04607v1 fatcat:ch2bi3qg4zgfhng5oqejwrfdbm

Transport and Acceleration of Solar Energetic Particles from Coronal Mass Ejection Shocks

David Ruffolo
2004 Proceedings of the International Astronomical Union  
After a brief overview of solar energetic particle (SEP) emission from coronal mass ejection (CME) shocks, we turn to a discussion of their transport and acceleration.  ...  Important progress has also been made on the transport of low energy SEP from very strong events, which can display exhibit interesting saturation effects and compositional variations.  ...  However, this limit to the acceleration process is an important component of our understanding of SEP acceleration, and should be understood physically.  ... 
doi:10.1017/s1743921305000803 fatcat:dsqxjz7xejhk5ci2blbom7n5zq

Energetic Particle Observations [chapter]

B. Klecker, H. Kunow, H. V. Cane, S. Dalla, B. Heber, K. Kecskemety, K. -L. Klein, J. Kota, H. Kucharek, D. Lario, M. A. Lee, M. A. Popecki (+5 others)
2006 Space Sciences Series of ISSI  
In this paper we review the measurements of energetic particles in interplanetary space and discuss their implication for our understanding of the sources, and of acceleration and propagation processes  ...  The characteristics of solar energetic particles (SEP) as observed in interplanetary space provide fundamental information about the origin of these particles, and the acceleration and propagation processes  ...  Based on these and other observations SEPs were classified as 'impulsive' and 'gradual', following a classification of flares based on the duration of soft Xrays (Pallavicini et al., 1977) .  ... 
doi:10.1007/978-0-387-45088-9_11 fatcat:6ys7pgunzrbcbhxcpbho4n2oei

Energetic Particle Observations

B. Klecker, H. Kunow, H. V. Cane, S. Dalla, B. Heber, K. Kecskemety, K.-L. Klein, J. Kota, H. Kucharek, D. Lario, M. A. Lee, M. A. Popecki (+5 others)
2006 Space Science Reviews  
In this paper we review the measurements of energetic particles in interplanetary space and discuss their implication for our understanding of the sources, and of acceleration and propagation processes  ...  The characteristics of solar energetic particles (SEP) as observed in interplanetary space provide fundamental information about the origin of these particles, and the acceleration and propagation processes  ...  Based on these and other observations SEPs were classified as 'impulsive' and 'gradual', following a classification of flares based on the duration of soft Xrays (Pallavicini et al., 1977) .  ... 
doi:10.1007/s11214-006-9018-9 fatcat:khiwjyl7f5alzewirqjrphk2ea

Gamma-ray bursts and collisionless shocks

E Waxman
2006 Plasma Physics and Controlled Fusion  
I review in this talk the phenomenological considerations, based on which these characteristics are inferred, and the challenges posed to our current models of particle acceleration and magnetic field  ...  the acceleration of particles to a power-law energy spectrum, d n/d E -2, possibly extending to 10^20eV.  ...  Our current understanding of, and open questions related to, particle acceleration are discussed in § III B.  ... 
doi:10.1088/0741-3335/48/12b/s14 fatcat:v4wiesa7fnftph5twi6ybuorxi

Laser wakefield simulations towards development of compact particle accelerators

C G R Geddes, D Bruhwiler, J R Cary, E Cormier-Michel, E Esarey, C B Schroeder, W A Isaacs, N Stinus, P Messmer, A Hakim, K Nakamura, A J Gonsalves (+8 others)
2007 Journal of Physics, Conference Series  
Realization of this potential requires understanding of accelerator physics to advance beam performance and stability, and particle simulations model the highly nonlinear, kinetic physics required.  ...  Laser driven wakefield accelerators produce accelerating fields thousands of times those achievable in conventional radio-frequency accelerators, offering compactness and ultrafast bunches to potentially  ...  The electron bunch then accelerates , which well matches the experimental spectrum. The close match of experimental parameters and results allows internal dynamics to be inferred.  ... 
doi:10.1088/1742-6596/78/1/012021 fatcat:4nh33lb23fetnk2c3sg5hlobza

Page 544 of Astronomy and Astrophysics Vol. 232, Issue 2 [page]

1990 Astronomy and Astrophysics  
It seems as if the y-ray limb-brightening observations may tell us as much, or more, about the form of the magnetic field and den- sity variations throughout the atmosphere, as they do about particle acceleration  ...  Astrophys. 232, 544-555 (1990) ASTRONOMY AND ASTROPHYSICS Implications of the solar flare y-ray limb-brightening observations for particle acceleration and the flare magnetic environment II.  ... 

A Tale of Cosmic Rays Narrated in γ Rays by Fermi

Luigi Tibaldo
2014 Brazilian journal of physics  
Because cosmic rays are charged particles scrambled by magnetic fields, combining direct measurements with other observations is crucial to understanding their origin and propagation.  ...  As energetic particles traverse matter and electromagnetic fields, they leave marks in the form of neutral interaction products.  ...  These include NASA and DOE in the US, CEA/Irfu and IN2P3/CNRS in France, ASI and INFN in Italy, MEXT, KEK, and JAXA in Japan, and the K. A.  ... 
doi:10.1007/s13538-014-0221-y fatcat:w4zamsarmfdbjbxgfdrhxpxe4e

SPATIAL OFFSETS OF INTERPLANETARY ION AND ELECTRON SOURCE REGIONS

E. E. Chollet, J. Giacalone, R. M. Skoug, J. T. Steinberg, J. T. Gosling
2009 Astrophysical Journal  
We present Advanced Composition Explorer (ACE) observations of interplanetary energetic ion and suprathermal electron events with intensity variations related to connection or lack thereof to the particle  ...  Observations of impulsive solar energetic particles provide unique insight into the process of particle acceleration in the solar atmosphere.  ...  INTRODUCTION Though acceleration of charged particles is ubiquitous in the universe, a detailed understanding of the mechanisms involved remains a great puzzle.  ... 
doi:10.1088/0004-637x/705/2/1492 fatcat:ahr6kliwjvegddmy45mmakozyi

Gamma Radiation from Flare-Accelerated Particles Impacting the Sun [chapter]

2006 Solar Eruptions and Energetic Particles  
We discuss how remote observations of gamma-ray lines and continua provide information on the population of electrons and ions that are accelerated in solar flares.  ...  maintaining the data needed, and completing and reviewing the collection of information.  ...  This work was supported by NASA DPR 10049 and NNG04ED1 81, and by the Office of Naval Research.  ... 
doi:10.1029/165gm17 fatcat:tqtclzyqbfc77dscr4b2gj3uji

What causes the variations of the peak intensity of CIR accelerated energetic ion fluxes?

E. Keppler
1998 Annales Geophysicae  
The variation of the peak intensity of energetic ions accelerated at CIR related shocks in the interplanetary medium as observed by instruments on board of ULYSSES during its pass towards the south polar  ...  Therefore ULYSSES data is compared with earlier observations by the PIONEER and VOYAGER spacecraft and concluded that the major part of the observed variation of the peak intensity seems to be due to a  ...  Roelof and another referee for their help in evaluating this paper.  ... 
doi:10.1007/s00585-998-1552-1 fatcat:nd3zqjwzsvbsdjwgfllqbtl43a

The high-energy Sun - probing the origins of particle acceleration on our nearest star

S. A Matthews, H. A. S. Reid, D. Baker, D. S. Bloomfield, P. K. Browning, A. Calcines, G. Del Zanna, R. Erdelyi, L. Fletcher, I. G. Hannah, N. Jeffrey, L. Klein (+13 others)
2021 Experimental astronomy (Print)  
AbstractAs a frequent and energetic particle accelerator, our Sun provides us with an excellent astrophysical laboratory for understanding the fundamental process of particle acceleration.  ...  Current X-ray and γ-ray spectroscopy provides only a basic understanding of accelerated particle spectra and the total energy budgets are therefore poorly constrained.  ...  The Sun as a laboratory for understanding particle acceleration. 2. What is the transition between plasma heating and particle acceleration? 3.  ... 
doi:10.1007/s10686-021-09798-6 fatcat:pawnjy5ubzgjdienyr7vhtdgpq

What causes the variations of the peak intensity of CIR accelerated energetic ion fluxes?

E. Keppler
1998 Annales Geophysicae  
The variation of the peak intensity of energetic ions accelerated at CIR related shocks in the interplanetary medium as observed by instruments on board of ULYSSES during its pass towards the south polar  ...  Therefore ULYSSES data is compared with earlier observations by the PIONEER and VOYAGER spacecraft and concluded that the major part of the observed variation of the peak intensity seems to be due to a  ...  Roelof and another referee for their help in evaluating this paper.  ... 
doi:10.1007/s005850050722 fatcat:rajrvq24kfhpjfquu2vknd4h2m
« Previous Showing results 1 — 15 out of 62,069 results