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Les "sauvages" des Lumières, II. Enjeux politiques
No full textLes articles composant ce dossier sont issus, comme le précédent publié dans le n° 44 de Lumières (2024/2), d'un colloque international qui s'est tenu aux universités de Cergy et de Paris 1 - Panthéon-Sorbonne en mai 2023.https://shs.cairn.info/revue-lumieres-2025-
A circularly polarized low-frequency radio burst from the exoplanetary system HD 189733
No full textInternational audienceAims. We aim to detect low-frequency radio emission from exoplanetary systems to gain insights into planetary magnetic fields, star–planet interactions, stellar activity, and exo-space weather. The HD 189733 system, hosting a well-studied hot Jupiter, is a prime target for such searches.Methods. We conducted NenuFAR imaging observations in the 15–62 MHz range to cover the entire orbital phase of HD 189733 b. Dynamic spectra were generated for the target and other sources in the field, followed by a transient search in the time-frequency plane. The data processing pipeline incorporated direction-dependent calibration and noise characterization to improve sensitivity. We also searched for periodic signals using a Lomb–Scargle analysis.Results. A highly circularly polarized radio burst was detected at 50 MHz, with a flux density of 1.5 Jy and a significance of 6σ at the position of HD 189733. No counterpart was found in Stokes I, likely because the emission is embedded in confusion noise and remains below the detection threshold. The estimated minimum fractional circular polarization of 38% suggests a coherent emission process. A periodicity search revealed no weaker signals linked to the planet’s orbital period, the star’s rotational period, or the synodic period and harmonic period between them. The burst’s properties are consistent with cyclotron maser instability (CMI) emission, however, the origin remains ambiguous. A comparison with theoretical models suggests star–planet interaction or stellar activity as potential origins. Alternative explanations such as contamination from other sources along the line of sight (e.g. the companion M dwarf) or noise fluctuation are plausible
L’ « Odysée Intestinale » : Éléments de réflexion sur le (non)-usage de la videocapsule grêlique et sur comment le redéfinir au-delà de l’IA”.
No full textInternational audienc
Astronomie pour l’éducation dans l’espace Francophone: Édition 2023
No full textInternational audienceLa seconde édition du colloque AstroEdu-Fr a eu lieu du 9 au 11 no-vembre 2023 au lycée Pierre Mendès France de Tunis et à l’Institut Régional de Formation (IRF) zone Maghreb-Est. Son ambition était de poursuivre la constitution d’une communauté francophone dans le domaine de l’astronomie pour l’éducation, en s’appuyant sur le bureau international de l’astronomie pour l’éducation (OAE) fondé par l’Union astronomique internationale (UAI), et en particulier le nœud francophone (OAENF-CY) hébergé par CY Cergy Paris Univer-sité. Quarante-cinq représentants de 11 pays francophones se sont retrouvés.Le programme du colloque a été constitué de conférences sur des thèmes liés à l’enseignement et la médiation de l’astronomie et sur des sujets d’actualités en astronomie, ainsi que d’ateliers en groupe restreint pour permettre la mise en œuvre et l’analyse de séances avec une participation active de chacun. Ce colloque s’adressait donc aux enseignants et enseignantes, formateurs et formatrices, médiateurs et médiatrices, chercheurs et chercheuses, intéressé.e.s par l’utilisation de l’astronomie pour l’éducation for-melle et informelle. Quarante-cinq représentants de 11 pays fran-cophones se sont retrouvés à Tunis
In Situ Monitoring of A Complex Model Structure Built With Green Wood and submitted to Real Climate Conditions
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Microcausality and Tunneling Times in Relativistic Quantum Field Theory
No full textInternational audienceWe show, in the framework of a space-time resolved relativistic quantum field theory approach to tunneling, that microcausality precludes superluminal tunneling dynamics. More specifically in this work dealing with Dirac and Klein-Gordon fields, we first prove that microcausality holds for such fields in the presence of a background potential. We then use this result to show that an intervention performed on a localized region of an initial wave packet subsequently scattering on a potential barrier does not result in any effect outside the light cone emanating from that region. We illustrate these results with numerical computations for Dirac fermions and Klein-Gordon bosons
In silico and in vitro assessments of thio-linked pyrimidine-based compounds against Leishmania donovani
No full textInternational audienceCaused by Leishmania parasites, leishmaniases are a group of pathologies acknowledged by the World Health Organization as neglected tropical diseases. Current therapies for treating these infections count on a limited arsenal of drugs with several downsides that restrict their use, namely the development of drug resistance. Innovative medicines with improved efficacy, safety, and a lower tendence for resistance development are imperatively needed.1 Trypanothione reductase (TR) critical function in sustaining the parasite's redox machinery, converting the disulfide bond of trypanothione disulfide (TS2) into reduced trypanothione T(SH)2, makes it a promising biomolecular target in the search for novel antileishmanial compounds. This di-thiol is crucial for scavenging reactive species for Leishmania2,3, offering a potential avenue for drug development. Furthermore, TR offers several advantages, highlighting its structural resemblance to all Trypanosomatidae parasites and its absence in the mammalian host.4 In the search for improved antileishmanial options, a study discovered the potential of aryl sulfides in deactivating TR.3,5 Based on these findings, we unveil the synthesis of a library of novel thio-linked pyrimidine-based compounds applying the Buchwald–Hartwig reaction that leads to the formation of different products by changing the reaction time. Our findings from the computational studies show that all compounds interact with the residues from the NADPH-binding site, thus limiting the interaction between TR and its cofactor, NADPH. We also provide the results of all compounds' in vitro antileishmanial activity against L. donovani axenic and intramacrophage amastigotes, and their cytotoxicity against Raw 264.7 cells. Compounds IC69 and IC90 were the most effective against both forms of Leishmania, exhibiting IC50 values lower than the control, miltefosine (Figure 1)
Contre l'extractivisme épistémique : prévenir l'exploitation des savoirs en Amérique latine
No full textInternational audienceEn tant que laboratoire politique, économique et social, l’Amérique latine est un terrain d’investigation privilégié, notamment pour les chercheurs étrangers. Depuis une quinzaine d’années cependant, ces derniers ont pu être accusés de contribuer à un « extractivisme épistémique » décrié. Ce concept désigne la quête effrénée d’informations brutes par des chercheurs peu sensibilisés à la nécessité de se montrer reconnaissants vis-à-vis des interlocuteurs auprès desquels et grâce auxquels ils ont conduit leurs recherches. Loin des faux-semblants que peuvent constituer les comités d’éthique universitaires, nous proposons de privilégier une forme de contrat moral personnel. Ainsi nous paraît-il nécessaire de s’engager à exprimer notre reconnaissance à nos interlocuteurs, d’une manière ou d’une autre, via un « retour » sur les conditions d’exercice de la recherche, qui pourra se faire, par exemple, sous la forme d’un rapport a minima oral. Nous qualifions ce type de communication de « rétrospective »
ODDITY : Entretien avec Alessandro Bavari
No full textInternational audienceMV : Alessandro, comment êtes-vous arrivé à ce type de création numérique ? AB : Comment êtes-vous arrivé à ce type de création numérique ? Pour répondre à cette question il faudrait remonter plusieurs décennies en arrière, à la manière de Benjamin Button. Depuis que je suis enfant, j’ai été attiré par les « bizarreries » de toutes sortes. J’étais attiré par le bizarre et par tout ce qui résidait dans les plis de la pénombre. Alors je me suis retrouvé à soulever de grosses pierres pour voir ce qui se cachait dessous, j’ai creusé dans les algues de la mer ou des ruisseaux, j’ai fendu les pierres pour regarder à l’intérieur. Et systématiquement, j’ai été surpris par cet univers parallèle que j’y ai trouvé..
From Hostility to Inclusivity for Migrants in Eastern Europe: Digital and Media Literacy Against Online Hate Speech
No full textInternational audienceSince the official launch of online social networks in the 1990s, the number of users and offered services has risen progressively, affecting societies and daily life. In some cases, these online platforms have been a breeding ground for radical groups to share their point of view on migrants, leading to incidents of disinformation. On that note, the current research paper aims to examine the digital literacy rates in Bulgaria and Romania, the two EU Member States in Eastern Europe that recently entered the Schengen Area, and monitor the shift of public opinion towards migrants inrecent years. Eventually, the paper demonstrates how the ability to track and report misleading information on migrant stories and integration policies in digital platforms can be a significant factor in reducing the spread of hate speech across different social groups. By utilizing a mixed-methods approach, namely investigating national reports on digital and media literacy, and tracking down the changes in public perception, this study sheds light on the initiatives implemented in those countries to combat hate speech and discrimination against migrants. Additionally, through the finding analysis, the paper concludes with key remarks on how policy recommendations can be formed based ondecisions on regional and transnational levels. Ultimately, the study results can be the basis for future research on the correlation between education level and media interpretation