HAL-CEA
Not a member yet
145450 research outputs found
Sort by
First observation of ultra-long-range azimuthal correlations in low multiplicity pp and p-Pb collisions at the LHC
No full textInternational audienceThis study presents the first observation of ultra-long-range two-particle azimuthal correlations with pseudorapidity separation of () in proton-proton (pp) and () in proton-lead (p-Pb) collisions at the LHC, down to and below the minimum-bias multiplicity. Two-particle correlation coefficients () are measured after removing non-flow (jets and resonance decays) contributions using the template-fit method across various multiplicity classes, providing novel insights into the origin of long-range correlations in small systems. Comparisons with the 3D-Glauber + MUSIC + UrQMD hydrodynamic model reveal significant discrepancies at low multiplicities, indicating possible dynamics beyond typical hydrodynamic behavior. Initial-state models based on the Color Glass Condensate framework generate only short-range correlations, while PYTHIA simulations implemented with the string-shoving mechanism also fail to describe these ultra-long-range correlations. The results challenge existing paradigms and question the underlying mechanisms in low-multiplicity pp and p-Pb collisions. The findings impose significant constraints on models describing collective phenomena in small collision systems and advance the understanding of origin of long-range correlations at Large Hadron Collider (LHC) energies
Variability of bottom dissolved oxygen on the southern Senegalese shelf at intraseasonal to interannual time scales using a modelling approach
No full textInternational audienc
Biochars improve agricultural production: The evidence base is limited
No full textInternational audienc
Activity of low-mass stars in the light of spot signature in the Fourier domain
No full textInternational audienceContext. Magnetic fields exhibit a wide variety of behaviours in low-mass stars and further characterisation is required to understand these observations. Stellar photometry from space missions such as MOST, CoRoT, Kepler, and TESS (and in the near future PLATO) provide thousands of highly precise light curves (LCs) that can shed new light on stellar activity, in particular through the signature of transiting spots.Aims. We study the impact of star spots on LCs in the Fourier domain, reducing the degeneracies encountered by direct spot modelling in the temporal domain. We use this new formulation to explore the spot properties from the available data.Methods. We propose a model of LC power spectra at low frequency based on a description of spot transits that allows us to retrieve information about the amplitude of their photometric impact ℋ and about the spot mean lifetime over the observation τlife when the power spectrum exibits rotation peaks. We validated this method with simulated LCs and then applied it to the Kepler data to extract global trends over a set of more than 37 755 stars.Results. Our analysis leads to a classification of the sample into ‘peakless’ or ‘with peaks’ spectra and enables the identification of different activity regimes based on ℋ and τlife for different Rossby number ranges. More specifically, we observed an intense regime of activity between Ro = 0.7 and Ro = 1, for stars with masses under 1 M⊙.Conclusions. This new systematic method can be used to provide new observational constraints on stellar activity (and possibly a link with stellar magnetism) when applied to large photometric datasets, such as those from the future PLATO mission
Evaluations of the decay data of Mn, mMn, I and Cs from the Decay Data Evaluation Project (DDEP) – 2021
No full textInternational audienceSince 1995, members of the Decay Data Evaluation Project (DDEP) have evaluated the decay data from different radionuclides of special interest for metrology or practical applications, e.g. nuclear medicine, monitoring and reactor shielding, etc. Since 2004, these evaluations have regularly been published under the auspices of the Bureau International des Poids et Mesures (BIPM) on behalf of the Consultative Committee for Ionizing Radiation (Comité Consultatif des Rayonnements Ionisants, CCRI).DDEP evaluations finalised in 2021 are published with their Tables, which summarise the recommended data of the radionuclides and their decay schemes, and the evaluator’s report describing the evaluation procedure (Comments)
FDSOI spin qubits platform for scalable quantum computing
No full textInternational audienceSilicon (Si) and germanium (Ge) semiconductor spin qubits are promising candidates for large-scale, fault-tolerant quantum computing due to their compatibility with established microelectronics fabrication and their long spin coherence times using isotopically enriched materials [1]. Achieving the million-qubit scale required for full error correction necessitates low device variability [2]. CEA-Leti's FDSOI spin qubit platform addresses this by employing industrial processes [3-5]. This work presents CEA-Leti's latest progress in fabricating scalable linear quantum dot (QD) arrays, prioritizing fabrication yield and uniformity for reliable operation at room and cryogenic temperatures. We also introduce new room-temperature parametric tests specific to these devices and highlight the benefits of using the back-gate for independent control of QD readout and exchange regimes. This work is partly funded by the EU through the H2020 QLSI project and the European Research Council (ERC) Synergy QuCube project
Annotating Bioconductor packages using the EDAM ontology
No full textInternational audienceBackground. EDAM is an ontology defining and standardising terms for the analysis and management of data in life sciences, including topics, operations, data types and formats. It allows the annotation of digital resources, improving their FAIRification. Bioconductor, an open-source project providing 2,000 packages for a wide range of bioinformatics applications, uses the biocViews vocabulary for the description of package metadata. However it is not defined and structured like an ontology and is made for internal use only, limiting the interoperability of the packages with other resources. In order to increase the visibility and interoperability of Bioconductor packages, we aim for their metadata annotation using the EDAM ontology, and their automated integration into the ELIXIR bio.tools registry and Research Software Ecosystem.Results. In order to shift from biocViews annotations to EDAM annotations, we mapped the existing vocabulary against the ontology and manually curated the results, mostly consisting of “topics” and “operations”. We developed scripts that extract Bioconductor package metadata and automatically incorporate them into the ELIXIR Research Software Ecosystem and bio.tools registry. Finally, we are working on the automated annotation of packages using LLM-based methods in order to further describe their input and output data types, to be synchronised with the ecosystem as well. Conclusions. This project improves the FAIRification of software resources for life science, and further extends the ELIXIR ecosystem. Beyond advancing the EDAM standard, this initiative builds a collaborative bridge between the Bioconductor and ELIXIR communities
Germanium atoms exceed the tetrahedral coordination in MFI zeolite
No full textInternational audienceGermanium is known to occupy tetrahedral sites by substituting silicon in germanosilicate zeolites. In this study, we present pioneering findings regarding the synthesis of zeolites with an MFI structure (GeMFI) incorporating a high germanium amount (16% Ge). Remarkably, the germanium atoms feature a slight electron deficiency with respect to GeO2, and the typical coordination number of 4, as usually reported for the germanosilicate zeolites, is exceeded, giving rise to Ge dimers in a double-bridge configuration. Notably, the compensation of the ammonium template is achieved not through fluorine ions in the [456] cages of the framework, as conventionally considered, but rather through oxygen. The GeMFI zeolite with the high Ge content reported in this work demonstrated exceptional thermal and hydrothermal stability, surpassing up to 1050 °C, thanks to both the double-bridge configuration and the defect-free structure. The unexpected role of germanium in MFI zeolite challenges previous assumptions, representing a paradigm shift in the understanding of porous germanosilicate structures, paving the way for a reevaluation of their synthesis, hydrolysis, and potential applications
Zeolite composite prepared by quasi in-situ interzeolite conversion approach
No full textInternational audienceThe design of zeolites with optimized textural properties is a continuous goal. Here we report a composite comprising mesoporous ultra stable zeolite Y (USY) and nanosized ZSM-5 with enhanced acid site accessibility and pore connectivity through quasi in-situ interzeolite conversion in a solvent-free medium. It begins with a spatial and elemental-biased dissolution of USY with impregnated TPAOH. This results in a hierarchical zeolite with increased mesopore volume and improved pore connectivity. Simultaneously, the solute provides all the necessary nutrients for the growth of ZSM-5 zeolite. Due to the constrained mass transfer during the quasi-solid-state dissolution, the resulting ZSM-5 crystals are as small as 10 nm and intimately connected with the USY zeolite. The advantageous synergy between zeolites Y and ZSM-5 in the composite was demonstrated through the methanol-to-olefin reaction and the cracking of n-hexane
