HAL-CEA
Not a member yet
145450 research outputs found
Sort by
The dark matter content of Milky Way dwarf spheroidal galaxies: Draco, Sextans and Ursa Minor
No full textInternational audienceThe Milky Way Survey of the Dark Energy Spectroscopic Instrument (DESI) has so far observed three classical dwarf spheroidal galaxies (dSphs): Draco, Sextans and Ursa Minor. Based on the observed line-of-sight velocities and metallicities of their member stars, we apply the axisymmetric Jeans Anisotropic Multi-Gaussian Expansion modeling (JAM) approach to recover their inner dark matter distributions. In particular, both the traditional single-population Jeans model and the multiple population chemodynamical model are adopted. With the chemodynamical model, we divide member stars of each dSph into metal-rich and metal-poor populations. The metal-rich populations are more centrally concentrated and dynamically colder, featuring lower velocity dispersion profiles than the metal-poor populations. We find a diversity of the inner density slopes of dark matter halos, with the best constraints by single-population or chemodynamical models consistent with each other. The inner density slopes are , and for Draco, Sextans and Ursa Minor, respectively. We also present the measured astrophysical J and D factors of the three dSphs. Our results indicate that the study of the dark matter content of dSphs through stellar kinematics is still subject to uncertainties behind both the methodology and the observed data, through comparisons with previous measurements and data sets
Roadmap on Neuromorphic Photonics
No full textThis roadmap consolidates recent advances while exploring emerging applications, reflecting the remarkable diversity of hardware platforms, neuromorphic concepts, and implementation philosophies reported in the field. It emphasizes the critical role of cross-disciplinary collaboration in this rapidly evolving field
Bridging time-delayed microwave radiometric observations and deep convection characteristics: a machine learning approach for the C²OMODO mission
No full textInternational audienceDeep convective cloud systems are central to the global water and energy cycle, and yet their representation in climate models remains challenging. This study explores the potential of machine learning to classify and characterize cloud structures inside cloud systems using radiometric measurements from the planned C²OMODO (Convective Core Observation through MicrOwave Derivative in the trOpics) mission. The relationships between cloud structure (anvil, stratiform, convective, and deep convective) and geophysical variables such as ice water path as well as integrated vertical ice momentum are investigated using a gradient boosting algorithm both for classification and regression purposes. The gradient boosting classification method achieves an overall accuracy (True Positive) above 70%. Retrievals of the geophysical variables yield R² ranging from 0.60 to 0.99. Furthermore, it is shown that applying a prior classification of the scenes improves the performances of the retrieval. This study highlights the potential of the forthcoming C²OMODO mission in advancing our understanding of convective systems and paves the way for in-depth studies on alternative or refined classification schemes and inputs, which could deliver even better results
Search for the nonresonant and resonant production of a Higgs boson in association with an additional scalar boson in the final state in proton-proton collisions at = 13 TeV
No full textInternational audienceThe results of a search for the production of two scalar bosons in final states with two photons and two tau leptons are presented. The search considers both nonresonant production of a Higgs boson pair, HH, and resonant production via a new boson X which decays either to HH or to H and a new scalar Y. The analysis uses up to 138 fb of proton-proton collision data, recorded between 2016 and 2018 by the CMS experiment at the LHC at a center-of-mass energy of 13 TeV. No evidence for signal is found in the data. For the nonresonant production, the observed (expected) upper limit at 95% confidence level (CL) on the HH production cross section is set at 930 (740) fb, corresponding to 33 (26) times the standard model prediction. At 95% CL, HH production is observed (expected) to be excluded for values of outside the range between 12 (9.4) and 17 (15). Observed (expected) upper limits at 95% CL for the XHH cross section are found to be within 160 to 2200 (200 to 1800) fb, depending on the mass of X. In the X Y()H() search, the observed (expected) upper limits on the product of the production cross section and decay branching fractions vary between 0.0591.2 fb (0.0870.68 fb). For the X Y()H() search the observed (expected) upper limits on the product of the production cross section and Y branching fraction vary between 0.6915 fb (0.738.3 fb) in the low Y mass search, tightening constraints on the next-to-minimal supersymmetric standard model, and between 0.6410 fb (0.707.6 fb) in the high Y mass search
Structure studies of Db through combined α, γ and internal-conversion-electron spectroscopy
No full textInternational audienceThis work reports on the study of the decay properties along the Db decay chain using the GABRIELA setup. The first observation of a high-K isomer in Db is presented. In addition, an unreported -decay branch in Md has been evidenced, allowing to constrain the differences in energy of the -decaying levels in Md, Lr and Db. Finally, the combination of the observed fine structure -decay from the high-spin state in Db with the first observation the internal decay in Lr requires a revision of level and decay scheme. In particular, a change of parity for the high-spin state from 9/2 to 9/2 in the Db is suggested, and the implications of such a change are also discussed
Nanoscale Mapping of the Structural Relaxation in Microstructured InxGa1−xN Pseudosubstrates by Scanning X-ray Diffraction Microscopy
No full textInternational audienceThe technological advancement of mobile devices for virtual and augmented reality requires displays that are faster, more energy-efficient, and of higher resolution. In x Ga 1− x N-based micro-light-emitting diodes (LEDs) have the potential to realize such advanced displays thanks to their ability to provide emission of red, green, and blue light simply by tuning the In concentration. However, efficient emission in the red still remains a challenge, as it requires high In contents (≈30–40%) that are unobtainable in In x Ga 1− x N epitaxial layers pseudomorphically strained to GaN substrates. Research efforts have therefore focused on achieving elastic relaxation of the active In x Ga 1− x N portion of the LED device to allow greater In incorporation, e.g., through the addition of partially relaxed intermediate In x Ga 1− x N layers in the heterostructure. Herein, the extent of strain relaxation in In x Ga 1− x N pseudosubstrates grown on GaN-on-sapphire substrates as induced by patterning in mesas 10 μm 2 in size is evaluated. Using synchrotron-based scanning X-ray diffraction microscopy, the lattice strain and tilt are mapped in a single mesa as well as in an ensemble of mesas with ≈60 nm spatial resolution, demonstrating the effectiveness of the processing route in producing high-quality, partially relaxed In x Ga 1− x N pseudosubstrates
The rhizobial type III effectors ErnA and Sup3 hijack the SUMOylation pathway to trigger nodule formation in Aeschynomene species
No full textInternational audienceRhizobial type III effectors (T3Es) play a crucial role in the symbiotic relationship between rhizobia and legumes by manipulating host cellular processes to promote nodule formation. Previously, we identified two T3Es, ErnA and Sup3, that trigger nodulation in Aeschynomene spp. in the absence of Nod factors. Here, we further investigate the mode of action of these T3Es during root nodule symbiosis. We employed protein interaction assays, in vitro binding and enzymatic activity assays, mutational analyses, and functional nodulation tests to dissect the roles of ErnA and Sup3 and their interactions with the host Small Ubiquitin‐like MOdifier (SUMO) pathway (SUMOylation). We demonstrate that ErnA contains a SUMO‐interacting motif (SIM) at its C terminus, which promotes its interaction with SUMO proteins in vitro and in plant nuclei. Additionally, we show that Sup3 possesses a C‐terminal SUMO protease domain, which not only interacts with SUMO proteins in vitro and in the nucleus but also exhibits SUMO protease activity. Deletion of the SIM in ErnA or mutation of the catalytic site in Sup3 abolished their ability to trigger nodulation in Aeschynomene indica . These findings suggest that type III secretion system‐dependent symbiosis is regulated by posttranslational modification through SUMOylation and that ErnA and Sup3 modulate this SUMOylation pathway to trigger nodulation
Preliminary results on industrial 28nm FD-SOI phase change memory at cryogenic temperature
No full textInternational audienc
Generic method to assess transmutation feasibility for nuclear waste treatment and application to irradiated graphite
No full textInternational audienceGraphite-moderated nuclear reactors have already produced more than 250000 tons of irradiated nuclear graphite, or i-graphite, world-wide. The sustainability of this technology relies on the end-of-life management of its moderator, which is activated into a long-lived nuclear waste, by neutron fluxes, during operating time. In particular, C14 is created. Nuclear transmutation, enabled by laser-driven particle acceleration, has been envisioned as a potential novel treatment scheme for long-lived nuclear waste. By triggering controlled nuclear reactions with energetic particles, long-lived radionuclides could be transformed into stable isotopes. Such a system could treat the C14 nuclei trapped within the i-graphite matrix, which is difficult to isolate by other means. This work performs a quantitative preliminary study of this transmutation scheme, in order to assess its feasibility at an industrial scale. The method used can be transposed to assess any transmutation scheme using a beam of particles directly sent on the material to be treated. First, a nuclear interaction channel which transmutes C14 nuclei without creating new long-lived radionuclides is identified. It consists in the choice of a type of particle, among which protons, gamma photons and neutrons can all be accelerated by laser-matter interaction; and it is completed by the adequate energy at which this particle must be sent on i-graphite. To that end, the nuclear cross-sections of C12, C13 and C14 are reviewed, neglecting other impurities in i-graphite. Then, based on the interaction channel identification, the energy cost of this scheme is estimated. Protons between 1 and 5 MeV make it possible to transmute C14 without creating any new long-lived activity. However, our result show that, even in this favorable reaction channel, the transmutation energy cost is too high for an i-graphite transmutation scheme to be feasible