1,721,066 research outputs found
Tracing the ICME plasma with a MHD simulation
Full text linkThe determination of the chemical composition of interplanetary coronal mass ejection (ICME) plasma is an open issue. More specifically, it is not yet fully understood how remote sensing observations of the solar corona plasma during solar disturbances evolve into plasma properties measured in situ away from the Sun. The ambient conditions of the background interplanetary plasma are important for space weather because they influence the evolutions, arrival times, and geo-effectiveness of the disturbances. The Reverse In situ and MHD APproach (RIMAP) is a technique to reconstruct the heliosphere on the ecliptic plane (including the magnetic Parker spiral) directly from in situ measurements acquired at 1 AU. It combines analytical and numerical approaches, preserving the small-scale longitudinal variability of the wind flow lines. In this work, we use RIMAP to test the interaction of an ICME with the interplanetary medium. We model the propagation of a homogeneous non-magnetised (i.e. with no internal flux rope) cloud starting at 800 km s−1 at 0.1 AU out to 1.1 AU. Our 3D magnetohydrodynamics (MHD) simulation made with the PLUTO MHD code shows the formation of a compression front ahead of the ICME, continuously driven by the cloud expansion. Using a passive tracer, we find that the initial ICME material does not fragment behind the front during its propagation, and we quantify the mixing of the propagating plasma cloud with the ambient solar wind plasma, which can be detected at 1 AU
Discovery of Small-scale Flows in the Void of a Coronal Mass Ejection with High-cadence Images Acquired by the Metis Coronagraph on Board Solar Orbiter
No full textBemporad, Alessandro et al.-- Full list of authors: Bemporad, Alessandro; Abbo, Lucia; Albert, Kinga; Amato, Emanuele; Andretta, Vincenzo; Biondo, Ruggero; Burtovoi, Aleksandr; Calchetti, Daniele; Da Deppo, Vania; De Leo, Yara; Fineschi, Silvano; Frassati, Federica; Grimani, Catia; Jerse, Giovanna; Landini, Federico; Mancuso, Salvatore; Naletto, Giampiero; Nicolini, Gianalfredo; Pancrazzi, Maurizio; Blanco Rodríguez, Julian; Romoli, Marco; Russano, Giuliana; Sasso, Clementina; Spadaro, Daniele; Stangalini, Marco; Strecker, Hanna; Orozco Suárez, David; Susino, Roberto; Teriaca, Luca; Uslenghi, Michela; Valori, GherardoOn 2022 March 26, the ESA Solar Orbiter mission observed the early evolution of a coronal mass ejection (CME). On that day, the spacecraft was at a heliocentric distance of 0.32 au and a longitude separation from Earth of 74 .° 5. The CME source region, observed with the Solar Orbiter Polarimetric and Helioseismic Imager magnetometer, shows no preexisting filament or flux rope. The event was first observed in the inner corona by the Solar Orbiter Extreme Ultraviolet Imager instrument with the Full Sun Imager telescope, showing the initial propagation of a flux rope seen face-on in the EUV, and formed during the eruption. Higher up, the event was observed by Metis with the Visible Light channel with an unprecedented time cadence of 20 s and a spatial resolution of 20" corresponding to about 4600 km bin‑1. The sequence of total brightness images shows the existence of small-scale circular flows inside the expanding flux rope, surrounded by multiple nested arch-shaped features. These motions, never reported so far, occur inside the void of the CME, with projected speed ∼40% higher than the CME propagation speed. The formation of the flux rope during the eruption suggests that these motions can be interpreted as a signature of conversion of magnetic writhe into twist, starting from the shearing of a preexisting arcade. © 2025. The Author(s).Solar Orbiter is a space mission of international collaboration between ESA and NASA, operated by ESA. We are grateful to the ESA SOC and MOC teams for their support. Metis was built and operated with funding from the Italian Space Agency (ASI), under contracts to the National Institute of Astrophysics (INAF) and industrial partners. Metis was built with hardware contributions from Germany (Bundesministerium für Wirtschaft und Energie through DLR), from the Czech Republic (PRODEX), and from ESA. The Metis team thanks the former PI, Ester Antonucci, for leading the development of Metis until the final delivery to ESA. The EUI instrument was built by CSL, IAS, MPS, MSSL/UCL, PMOD/WRC, ROB, LCF/IO with funding from the Belgian Federal Science Policy Office (BELSPO/PRODEX PEA 4000112292 and 4000134088); the Centre National d'Etudes Spatiales (CNES); the UK Space Agency (UKSA); the Bundesministerium für Wirtschaft und Energie (BMWi) through the Deutsches Zentrum für Luft- und Raumfahrt (DLR); and the Swiss Space Office (SSO). The German contribution to SO/PHI is funded by the BMWi through DLR and by MPG central funds. The Spanish contribution to SO/PHI is funded by AEI/MCIN/10.13039/501100011033/ and European Union "NextGenerationEU/PRTR" (RTI2018-096886-C5, PID2021-125325OB-C5, PCI2022-135009-2, PCI2022-135029-2) and ERDF "A way of making Europe"; "Center of Excellence Severo Ochoa" awards to IAA-CSIC (SEV-2017-0709, CEX2021-001131-S); and a Ramón y Cajal fellowship awarded to DOS. The French to SO/PHIcontribution is funded by CNES. F. Frassati acknowledges support from INAF grant CUP C63C23000810005 "IDEA-SW—Integrating Data and Expertise to Advance Space Weather forecasting of Catastrophic Events" and from the Project "Supporto per la realizzazione degli strumenti Metis, SWA DPU e STIX" CUP F86C18000570005. A. Bemporad, R. Biondo, S. Mancuso, and R. Susino acknowledge support by the Italian PRIN 2022, project 2022294WNB entitled "Heliospheric shocks and space weather: from multispacecraft observations to numerical modeling". Finanziato da Next Generation EU, fondo del Piano Nazionale di Ripresa e Resilienza (PNRR) Missione 4 "Istruzione e Ricerca" - Componente C2 Investimento 1.1, 'Fondo per il Programma Nazionale di Ricerca e Progetti di Rilevante Interesse Nazionale (PRIN).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S).With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (SEV-2017-0709).Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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