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Introduction. Prendre de la distance pour (re)penser la pratique de l’enquête de terrain
No full textInternational audiencePlutôt que d’étudier l’impact des Internet sur la société, ce dossier aborde la question plus prosaïque de la manière dont chercheuses et chercheurs peuvent accéder à, observer et rendre compte de cette expérience en ligne. Nous espérons ainsi contribuer au développement d’une attitude réflexive et critique sur les outils et méthodes de recherche à distance, tout en pensant l’ethnographie en ligne comme un nouveau paradigme de recherche. Ce dossier servira de support pour partager et discuter des récits de recherche qui s’emparent de l’expérience numérique. Il cherchera, à partir de ces récits, à questionner nos méthodologies classiques ou traditionnelles de collecte de données, ancrées dans l’immersion sur le temps long et l’observation directe, quand elles ne font plus sens au regard de nos pratiques
The HDAC inhibitor romidepsin renders liver cancer vulnerable to RTK targeting and immunologically active
No full textInternational audienceHistone deacetylases (HDACs) are epigenetic regulators frequently altered in cancer. Here we report that overexpression of HDAC1/2 occurs in Hepatocellular Carcinoma (HCC) patients, correlating with poor prognosis. We show that romidepsin, a class-I HDAC inhibitor, elicits a combinatorial perturbation of distinct molecular processes in HCC cells, altering lipid composition, mitotic spindle machinery, and levels of cell cycle/survival signals. Collectively, these alterations lead HCC cells to a vulnerable state, conferring dependency to receptor tyrosine kinase (RTK) signalling support. The cytostatic effects of romidepsin alone is converted into cytotoxicity by the RTK inhibitor cabozantinib in HCC models. We document that romidepsin+cabozantibib confers an immune-stimulatory profile in Alb-R26 mouse models, with direct effects on primary human dendritic cell maturation in vitro. Our findings put forward the intricate crosstalk between epigenetics, metabolism, and immune response in cancer. The broad action of romidepsin on distinct cellular functions highlights its therapeutic potential for HCC treatment
Ingénierie quantique de la lumière à l'aide d'atomes de Rydberg en cavité
No full textProducing interactions between optical photons is a critical step for implementing quantum communication protocols and photonic quantum computing. Achieving this goal requires a strongly nonlinear medium. This thesis presents a setup designed to facilitate such interactions, consisting of a small atomic cloud placed inside a medium-finesse optical cavity and driven to a highly excited Rydberg state. The collective nature of the atomic ensemble enhances the coupling between the cloud and the cavity light field, while Rydberg interactions suppress double excitations within the cloud. As a result, the atomic cloud behaves as an effective single tree-level collective “superatom” coupled to the cavity mode. The first part of this thesis addresses imperfections in the ideal superatom model by accounting for multiple Rydberg excitations within the cloud. A new theoretical model is introduced to describe the effects of an imperfect Rydberg blockade, specifically in the regime where up to two Rydberg excitations are possible. This model is then validated through a series of experiments, demonstrating its applicability within the experimental framework. In the second part, the internal state of the superatom is coherently controlled and mapped onto a free-propagating light mode to generate an optical qubit encoded as a quantum superposition of 0 and 1 photons. Photon-correlation measurements reveal the single-photon nature of the emitted states, with a strong antibunching effect and only a residual 0.5% probability of emitting two photons per pulse. The photonics states are generated in the desired spatiotemporal mode with a high 60% efficiency. Using homodyne-tomography measurements, the density matrix of the output states is reconstructed, leading to the Wigner functions. In agreement with theoretical predictions, these functions are quadraturesqueezed for small qubit rotation angles, and develop a negative region when the angle approaches p. In the third part, the experimental setup is upgraded to incorporate an additional atomic cloud within the cavity. Initial experiments focus on introducing an excitation into one superatom and transferring it through the cavity to the second superatom. The process achieves an efficiency of approximately 30 %, in close agreement with t heoretical predictions. These results pave the way for future advancements in realizing more complex quantum gates and communication protocols.Produire des interactions entre photons optiques est une étape cruciale pour la mise en œuvre de protocoles de communication quantique et de calcul quantique photonique. Pour atteindre cet objectif, un milieu fortement non linéaire est nécessaire. Cette thèse présente une configuration conçue pour faciliter de telles interactions, consistant en un petit nuage atomique placé à l’intérieur d’une cavité optique de finesse moyenne et excité jusqu’à un état de Rydberg. La nature collective de l’ensemble atomique renforce le couplage entre le nuage et le champ lumineux de la cavité, tandis que les interactions de Rydberg suppriment les doubles excitations au sein du nuage. Par conséquent, le nuage atomique se comporte comme un « superatome » collectif à trois niveaux, couplé au mode de la cavité. La première partie de cette thèse traite des imperfections du modèle idéal de superatome en prenant en compte les multiples excitations de Rydberg au sein du nuage. Un nouveau modèle théorique est introduit pour décrire les effets d’un blocage de Rydberg imparfait, dans le régime se limitant à deux excitations de Rydberg. Ce modèle est ensuite validé à travers une série d’expériences, démontrant sa validité dans le cadre expérimental qui nous intéresse. Dans la deuxième partie, l’état interne du superatome est contrôlé de manière cohérente et transféré à un mode lumineux libre pour générer un qubit optique encodé comme une superposition quantique de 0 et 1 photons. Les mesures de corrélation photonique révèlent la nature unique des états émis, avec un effet de dégroupement marqué et une probabilité résiduelle de 0,5 % d’émettre deux photons par impulsion. Les états photoniques sont générés dans le mode spatiotemporel souhaité avec une efficacité élevée de 60 %. Grâce à la tomographie homodyne, la matrice densité des états produit est reconstruite, permettant de calculer les fonctions de Wigner. En accord avec les prédictions théoriques, ces fonctions présentent une compression des quadratures pour de petits angles de rotation du qubit et développent une région négative lorsque l’angle approche p. Dans la troisième partie, le dispositif expérimental est amélioré pour inclure un deuxième nuage atomique dans la cavité. Les premières expériences se concentrent sur l’introduction d’une excitation dans un superatome et de son transfert, via la cavité, au deuxième superatome. Ce processus atteint une efficacité d’environ 30 %, en accord avec les prédictions théoriques. Ces résultats ouvrent la voie à de futurs progrès pour réaliser des portes quantiques plus complexes et des protocoles de communication quantique
Temporalities in Mesoamerican Ritual Practices
No full textInternational audienceTemporalities in Mesoamerican Ritual Practices examines the time-based dimensions of ritual activities in past and present Mesoamerican societies, including the prehispanic, colonial, and modern periods. The authors explore ritual around three principal categories of action—creating, transforming, and destroying—as significant cultural manifestations of the temporal dimension of transition processes. Based on specific case studies, new analysis of fieldwork data, and long-term collaboration between authors, chapters engage empirically and theoretically with the multiple temporalities of ritual in relation to both the unfolding of ritual performance and its external and symbolic anchors. Taking rituals as a series of specific formalized actions that produce transitory changes within an initial context, the authors examine activities that generate change linked to artifact production, life cycles, healing, conflict resolution, crisis management, the enthronement of rulers and transfers of responsibilities, and practices relating to the occupation, abandonment, reuse, or conversion of socialized spaces. Adopting a multidisciplinary approach in archaeology, ethnohistory, anthropology, and linguistic anthropology, Temporalities in Mesoamerican Ritual Practices offers new insights into ritual time approached through multi-semiotic, material, sensorial, and pragmatic perspectives that encourage further interdisciplinary dialogue
Takashi Tachibana, le populiste qui veut « faire exploser l’audiovisuel public »
No full textIn Japan, the House of Councillors elections concluded on July 20, resulting in Prime Minister Shigeru Ishiba losing his majority in the upper house for the first time in fifteen years. Against a backdrop of rising rice prices, U.S. customs tariffs, and numerous political scandals, far-right, populist, and anti-immigration parties made significant gains. Although he failed to win a seat in this election, candidate Takashi Tachibana and his movement, the “Party to Protect the People from NHK,” embody some of the new trends shaping Japan’s political landscape.Au Japon, les élections à la Chambre des conseillers se sont achevées le 20 juillet, se soldant pour le premier ministre Shigeru Ishiba par une perte de sa majorité à la Chambre haute, une première depuis quinze ans. Dans un contexte d'inflation du prix du riz, de taxes douanières américaines et de nombreux scandales politiques, les partis d'extrême droite, populistes et anti-immigration, ont réalisé une percée. S'il n'a pas réussi à obtenir de siège lors de cette élection, le candidat Takashi Tachibana et son mouvement, le « Parti qui protège la population de la NHK », incarnent certaines des nouvelles tendances qui marquent le monde politique japonais
The Galaxy Activity, Torus, and Outflow Survey (GATOS). VII. The 20–214 μm Imaging Atlas of Active Galactic Nuclei Using SOFIA
No full textInternational audienceWe present a 19.7–214 μ m imaging atlas of local (4–181 Mpc; median 43 Mpc) active galactic nuclei (AGN) observed with FORCAST and HAWC+ on board the SOFIA telescope with angular resolutions ~3 ″ –20 ″ . This atlas comprises 22 Seyferts (17 Type 2 and five Type 1) with a total of 69 images, 41 of which have not been previously published. The AGN span a range of luminosities of log 10 ( L bol [ erg s - 1 ] ) = [ 42 , 46 ] with a median of log 10 ( L bol [ erg s − 1 ] ) = 44.1 ± 1.0 . We provide the total fluxes of our sample using aperture photometry for point-source objects and a 2D Gaussian fitting for objects with extended host galaxy emission, which was used to estimate the unresolved nuclear component. Most galaxies in our sample are pointlike sources; however, four sources (Centaurus A, Circinus, NGC 1068, and NGC 4388) show extended emission in all wavelengths. The 30–40 μ m extended emission in NGC 4388 is coincident with the narrow-line region at PA ~ 50°, while the dusty extension at longer wavelengths arises from the host galaxy at PA ~ 90°. Our new observations allow us to construct the best-sampled parsec-scales (spectral energy distributions, SEDs) available between 30 and 500 μ m for a sample of nearby AGN. We estimate that the average peak wavelength of the nuclear SEDs is ~40 μ m in νF ν , which we associate with an unresolved extended dusty region heated by the AGN
Shock-driven heating in the circumnuclear star-forming regions of NGC 7582 : insights from JWST NIRSpec and MIRI/MRS spectroscopy
No full textInternational audienceWe present combined James Webb Space Telescope (JWST) NIRSpec and MIRI/MRS integral field spectroscopy data of the nuclear and circumnuclear regions of the highly dust obscured Seyfert 2 galaxy NGC 7582, which is part of the sample of active galactic nucleaus (AGN) in the Galaxy Activity, Torus and Outflow Survey (GATOS). Spatially resolved analysis of the pure rotational H lines (S(1)–S(7)) reveals a characteristic power-law temperature distribution in different apertures, with the two prominent southern star-forming regions exhibiting unexpectedly high molecular gas temperatures, comparable to those in the AGN powered nuclear region. We investigate potential heating mechanisms including direct AGN photoionization, UV fluorescent excitation from young star clusters, and shock excitation. We find that shock heating gives the most plausible explanation, consistent with multiple near- and mid-IR tracers and diagnostics. Using photoionization models from the PhotoDissociation Region Toolbox, we quantify the ISM conditions in the different regions, determining that the southern star-forming regions have a high density ( cm) and are irradiated by a moderate UV radiation field ( Habing). Fitting a suite of Paris-Durham shock models to the rotational H lines, as well as rovibrational 1-0 S(1), 1-0 S(2), and 2-1 S(1) H emission lines, we find that a slow ( km s−1) C-type shock is likely responsible for the elevated temperatures. Our analysis loosely favours local starburst activity as the driver of the shocks and circumnuclear gas dynamics in NGC 7582, though the possibility of an AGN jet contribution cannot be excluded
Formate Production from Simulated Quasi‐Flue Gas Combining a Molecular Catalyst and a Modified Electrode
No full textInternational audienceMolecular metal complexes form an important class of catalysts for the electroreduction of CO 2 (CO 2 RR) to carbon monoxide (CO) or formic acid (HCOOH), key processes in the context of the requested exploration of novel sources of carbon, alternative to fossil fuels. Research studies are most generally carried out with pure gas streams of CO 2 , while the available real sources of CO 2 are gases coming out from industrial plants and containing a low share of CO 2 , and a great diversity of impurities including nitrogen and sulfur oxides. Herein, it is shown that a molecular catalyst, [Rh(bpy)(Cp*)Cl]Cl (bpy = bipyridine, Cp* = pentamethylcyclopentadienyl), catalyzes CO 2 RR to formic acid using a quasi‐flue gas (5–10% CO 2 and 100 ppm NO 2 or 50 ppm SO 2 ) with substantial selectivity. This is made possible thanks to the modification of the cathode surface with a positively charged imidazolium layer, which greatly favors CO 2 RR over competing reactions, proton, NO 2 , and SO 2 reductions. These results highlight the potential of combining molecular catalysis and electrode surface modification for the electroreduction of diluted CO 2 without prior carbon capture or purification
Breakpoint electrochlorination in ammonia removal: Unveiling the impact of convective mass transfer
No full textInternational audienceBreakpoint chlorination, the point at which ammonia is completely oxidized by chlorine to nitrogen gas, may occur during electrochemical water treatment due to the simultaneous abundance of inorganic nitrogen species and chloride ions in many water matrices. Nevertheless, little is known about the difference between the chemical breakpoint chlorination and electrochemical ammonia abatement as well as the impact of the electrode-electrolyte interface that drives the breakpoint electrochlorination. This study investigates the influence of the interface on ammonia oxidation by comparing indirect breakpoint electrochlorination with chemical approach and by examining the impact of varying convective mass transfer on breakpoint electrochlorination. Our results revealed that, under identical conditions and bulk pH, breakpoint electrochlorination releases much lower residual chlorine species in the bulk solution before ammonia is oxidized, as compared to chemical breakpoint chlorination. It was observed that lower convective mass transfer not only accelerates ammonia removal but also increases the chlorine evolution reaction. Results from a closed divided cell experiment confirmed that chlorine evolution is enhanced under lower convective mass transfer, which suggests a relevant role of species distribution within electrodeelectrolyte interface. We hypothesize that this effect may be due to a more acidic local pH under lower mass transfer conditions, which favors chlorine evolution over oxygen evolution reaction. These findings provide insights into the fundamental differences of chemical breakpoint chlorination and indirect breakpoint electrochlorination. The results can guide operating strategies for electrochemical water treatment that can potentially reduce energy consumption by lowering flow speeds, while achieving higher chlorine yield and faster ammonia removal
Heating Dynamics of Correlated Fermions under Dephasing
No full textWe study the dissipative dynamics of correlated fermions evolving in presence of a local dephasing bath. To this extent we consider the infinite coordination limit of the corresponding Lindblad master equation, provided by Dynamical Mean-Field Theory for open quantum systems. We solve the resulting quantum impurity problem, describing an Anderson impurity coupled to a local dephasing, using weak-coupling perturbation theory in interaction and dephasing. We show that the dissipative dynamics describes heating towards infinite temperature, with a relaxation rate that depends strongly on interaction. The resulting steady-state spectral functions are however non-trivial and show an interplay between coherent quasiparticle peak and local dephasing. We then discuss how thermalization towards infinite temperature emerges within DMFT, by solving the impurity problem throughout its self-consistency. We show that thermalization under open quantum system dynamics is qualitatively different from the closed system case. In particular, the thermalization front found in the unitary is strongly modified, a signature of the irreversibility of the open system dynamics