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AGENT Guidelines for dataflow
No full textThe AGENT project aims at integrating data from different sources (genebanks, research institutes, international archives) and types (passport, phenotypic, genomic data). These guidelines have been developed to explain the data flow within the AGENT project and should be useful for other projects
Preservation of δ<sup>13</sup>C signatures in oak charred wood: Application to the "forest" of Notre-Dame de Paris
No full textInternational audienceThe fire of the Notre-Dame de Paris’s cathedral (NDP) in 2019 brought a unique opportunity to study the past environmental conditions in the region during the High Middle Ages through the charred oak beams of the “Forest” (name given to its framework). However, as a preamble, there is a need to evaluate the preservation of the stable carbon isotope signatures (δ13C) in response to changes in molecular composition, occurring with carbonisation. To this end, experimental studies were conducted on modern and NDP oak wood at both inter- and intra-annual levels. Laser ablation was used for the first time on burnt wood. Results show that regardless of the charring duration, at temperatures above 500 °C, carbonisation‑induced 13C fractionation shows a consistent decrease (Δ13C) of approximately 1 ‰ relative to uncharred values. Despite a slight decrease in variance, a strong and significant correlation (rmean = 0.9, p < 0.01) was observed between the uncharred time series and the carbonised counterpart, showing that the C isotopic variability is preserved. This study paves the way to use the charcoal remains from the Notre-Dame de Paris framework as a unique paleoenvironmental archive
DESI 2024 V: Full-Shape Galaxy Clustering from Galaxies and Quasars
No full textInternational audienceWe present the measurements and cosmological implications of the galaxy two-point clustering using over 4.7 million unique galaxy and quasar redshifts in the range $0.
Characterization of DESI fiber assignment incompleteness effect on 2-point clustering and mitigation methods for DR1 analysis
No full textInternational audienceWe present an in-depth analysis of the fiber assignment incompleteness in the Dark Energy Spectroscopic Instrument (DESI) Data Release 1 (DR1). This incompleteness is caused by the restricted mobility of the robotic fiber positioner in the DESI focal plane, which limits the number of galaxies that can be observed at the same time, especially at small angular separations. As a result, the observed clustering amplitude is suppressed in a scale-dependent manner, which, if not addressed, can severely impact the inference of cosmological parameters. We discuss the methods adopted for simulating fiber assignment on mocks and data. In particular, we introduce the fast fiber assignment (FFA) emulator, which was employed to obtain the power spectrum covariance adopted for the DR1 full-shape analysis. We present the mitigation techniques, organised in two classes: measurement stage and model stage. We then use high fidelity mocks as a reference to quantify both the accuracy of the FFA emulator and the effectiveness of the different measurement-stage mitigation techniques. This complements the studies conducted in a parallel paper for the model-stage techniques, namely the -cut approach. We find that pairwise inverse probability (PIP) weights with angular upweighting recover the "true" clustering in all the cases considered, in both Fourier and configuration space. Notably, we present the first ever power spectrum measurement with PIP weights from real data
Exploring HOD-dependent systematics for the DESI 2024 Full-Shape galaxy clustering analysis
No full textInternational audienceWe analyse the robustness of the DESI 2024 cosmological inference from fits to the full shape of the galaxy power spectrum to uncertainties in the Halo Occupation Distribution (HOD) model of the galaxy-halo connection and the choice of priors on nuisance parameters. We assess variations in the recovered cosmological parameters across a range of mocks populated with different HOD models and find that shifts are often greater than 20% of the expected statistical uncertainties from the DESI data. We encapsulate the effect of such shifts in terms of a systematic covariance term, , and an additional diagonal contribution quantifying the impact of our choice of nuisance parameter priors on the ability of the effective field theory (EFT) model to correctly recover the cosmological parameters of the simulations. These two covariance contributions are designed to be added to the usual covariance term, , describing the statistical uncertainty in the power spectrum measurement, in order to fairly represent these sources of systematic uncertainty. This approach is more general and robust to choices of model free parameters or additional external datasets used in cosmological fits than the alternative approach of adding systematic uncertainties at the level of the recovered marginalised parameter posteriors. We compare the approaches within the context of a fixed CDM model and demonstrate that our method gives conservative estimates of the systematic uncertainty that nevertheless have little impact on the final posteriors obtained from DESI data
Large quadrupole deformation in Ne challenges rotor model and modern theory: urging for clusters in nuclei
No full textInternational audienceThe spectroscopic quadrupole moment of the first excited state, , at 1.634 MeV in Ne was determined from sensitive reorientation-effect Coulomb-excitation measurements using a heavy target and safe energies well below the Coulomb barrier. Particle- coincidence measurements were collected at iThemba LABS with a digital data-acquisition system using the {\sc AFRODITE} array coupled to an annular, doubled-sided silicon detector. A precise value of eb was determined at backward angles in agreement with the only safe-energy measurement prior to this work, eb. This result adopts 1 shell-model calculations of the nuclear dipole polarizability of the 2 state that contributes to the effective quadrupole interaction and determination of . It disagrees, however, with the ideal rotor model for axially-symmetric nuclei by almost . Larger discrepancies are computed by modern state-of-the-art calculations performed in this and prior work, including {\it ab initio} shell model with chiral effective interactions and the multi-reference relativistic energy density functional ({\sc MR-EDF}) model. The intrinsic nucleon density of the 2 state in Ne calculated with the {\sc MR-EDF} model illustrates the presence of clustering, which explains the largest discrepancy with the rotor model found in the nuclear chart and motivates the explicit inclusion of clustering for full convergence of collective properties
Markov spin models for image generation: explicit large deviations with respect to the number of pixels
No full textInternational audienceAbstract For the discrete-time or the continuous-time Markov spin models for image generation when each pixel n = 1 , . . , N can take only two values S n = ± 1 , the finite-time forward propagator depends on the initial and on the final configurations of the N spins only via a single global variable, namely the extensive overlap that counts the number of spins that have the same value or not in the two configurations. The joint probability distribution of the overlap and of the magnetization during the forward noising dynamics can be written for any finite number N of pixels and in the limit N → + ∞ to extract the large deviation properties. The consequences for the backward reconstructive dynamics are then analyzed for various initial conditions, namely (i) a single image, (ii) a mixture of two images, (iii) when the initial condition corresponds to the Curie–Weiss mean-field ferromagnetic model in the microcanonical ensemble as a simple analog of the manifold-hypothesis concerning continuous generative diffusion models
Electrochemical sensors based on amorphous carbon electrode: A review
No full textInternational audienceAmorphous carbon, including diamond-like carbon (DLC) and carbon nitride (CNx), has emerged as a highly promising electrode material for electrochemical sensor development, owing to its exceptional physicochemical and electrochemical properties. These include a wide potential window, minimal background currents, high tolerance to extreme potentials, and enhanced resistance to fouling compared to conventional carbon-based electrodes. A major advantage of these materials is their cost-efficient production methods and the flexibility to synthesize them on a variety of substrates, including metals and polymers. This review aims to provide a comprehensive and up-to-date overview of electrochemical sensors based on amorphous carbon, serving as both a reference and a resource for researchers interested in leveraging these materials. It highlights the unique positioning of amorphous carbon compared to conventional electrode materials, emphasizing its advantages and potential applications. The discussion encompasses the physicochemical, electrochemical, and structural properties of amorphous carbon, with a focus on the influence of various deposition processes. Additionally, the review delves into advanced strategies such as doping and surface treatments that further enhance the performance of amorphous carbon coatings. Lastly, it presents a detailed compilation of electrochemical sensors utilizing amorphous carbon as the electrode material, showcasing their capabilities and the breadth of their applications in sensor technology
Radiation-Reaction and Angular Momentum Loss at
No full textInternational audienceWe point out that the contribution to the angular momentum loss for two-body scattering involving two radiation modes, , is determined by the radiation-reaction contribution to the one-loop waveform. The latter is proportional to the tree-level one, and this reduces the calculation of to cut two-loop integrals. We exploit this simplification, which follows from unitarity, to obtain a closed-form expression for for generic velocities, which resums all fractional post-Newtonian (PN) corrections to the angular momentum loss starting at 1.5PN
Identification of paramagnetic species in silver-doped barium–germanium–gallium glass exposed to electron irradiation
No full textInternational audienceIonizing irradiation was performed on barium-germanium-gallium (BGG) glasses using a 2.5 MeV electron beam. Through electron spin resonance spectroscopy, paramagnetic point defects, such as germanium-and gallium-related electron and hole trap centers, have been identified. The presence of silver in the BGG glass appears to hinder the stability of these defects at lower energy doses (10 4 Gy), with silver becoming the main trapping center. At higher energy doses (10 6 Gy), the glass undergoes structural modifications, hindering the trapping process of silver ions. Additionally, we evidence the importance of alkaline elements such as potassium and sodium on silver ions trapped centers' formation