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DESI EDR: Calibrating the Tully-Fisher Relationship with the DESI Peculiar Velocity Survey
No full textInternational audienceWe calibrate the Tully-Fisher relation (TFR) with data from the DESI Peculiar Velocity (PV) Survey taken during the Survey Validation (SV) period of the DESI galaxy redshift survey. Placing spectroscopic fibers on the centers and major axes of spatially-extended spiral galaxies identified in the 2020 Siena Galaxy Atlas using the DESI Legacy Surveys, we measure the rotational velocities at 0.33R26 for 1163 (1136 + 27 dwarf) spiral galaxies observed during SV. Using 41 spiral galaxies observed in the Coma Cluster, we find a slope for the TFR of -7.96+/-0.13 AB mag in the r-band, with a scatter about the TFR of 1.07+/-0.02 AB mag. We calibrate the zero-point of the TFR using galaxies with independent distances measured using type Ia supernovae via the cosmological distance ladder. From the SN Ia distances, we measure a zero-point of -19.34(+0.30,-0.29) AB mag in the r-band. We produce a public catalog of the distances to these 1136 spiral galaxies observed during DESI SV as part of the DESI PV Survey with our calibrated TFR. This is, to our knowledge, the first catalog of TFR distances produced with velocities measured at a single point in the disk
General theory of slow non-Hermitian evolution
No full textNon-Hermitian systems are widespread in both classical and quantum physics. The dynamics of such systems has recently become a focal point of research, showcasing surprising behaviors that include apparent violation of the adiabatic theorem and chiral topological conversion related to encircling exceptional points (EPs). These have both fundamental interest and potential practical applications. Yet the current literature features a number of apparently irreconcilable results. Here we develop a general theory for slow evolution of non-Hermitian systems and resolve these contradictions. We prove an analog of the adiabatic theorem for non-Hermitian systems and generalize it in the presence of uncontrolled environmental fluctuations (noise). The effect of noise turns out to be crucial due to inherent exponential instabilities present in non-Hermitian systems. Disproving common wisdom, the end state of the system is determined by the final Hamiltonian only, and is insensitive to other details of the evolution trajectory in parameter space. Our quantitative theory, leading to transparent physical intuition, is amenable to experimental tests. It provides efficienttools to predict the outcome of the system’s evolution, avoiding the need to follow costly timeevolution simulations. Our approach may be useful for designing devices based on non-Hermitian physics and may stimulate analyses of classical and quantum non-Hermitian-Hamiltonian dynamics, as well as that of quantum Lindbladian and hybrid-Liouvillian systems
Competing effects of charge-carrier and impurity scattering limiting phonon heat conduction in heavily-doped silicon
No full textWith respect to undoped semiconductors, thermal transport by phonons is limited by two additional mechanisms when doping increases: charge-carrier and impurity scattering. Previous works provided contradicting conclusions on the dominant doping-induced scattering mechanism in silicon. In this work, we clarify the competing roles of impurity and charge-carrier scatterings of phonons in the reduction of the lattice thermal conductivity in n-and p-doped silicon, by comparing experimental results obtained with the 3ω method and predictive DFT-based calculations for a large set of doping concentrations and a wide temperature range. The analysis allows delimiting the doping and temperature ranges where (i) extrinsic scattering surpasses intrinsic (phonon-phonon and phonon-isotope) one and (ii) one of the two doping-induced mechanisms plays the dominant role. We observe that the experimental setup impacts both the thermal conductivity value and the critical doping concentration at which the thermal conductivity is reduced by half
Windows, fans, and solar shadings during summer and heatwave: Occupant behavior and potential for improvement in heat-mitigation practices
No full textInternational audienceOccupant behavior during summer and heatwaves has a strong impact on overheating in free-running residential buildings. Yet, the use of windows, solar shadings, and fans remains poorly studied. This study addresses this gap through the largest monitoring campaign of its kind in France on this topic, covering 76 dwellings across three regions in summer 2023. Window states, solar shading positions, fan use, and indoor and outdoor conditions were systematically monitored for four months. Behaviors were analyzed individually and in combination to better understand real behavior in this context and assess the adoption of heat-mitigation practices and their potential for improvement.Results reveal substantial diversity across dwellings and through summer periods. General tendencies are consistent with previous datasets from other countries and contexts, with two main differences. Fan use is over four times lower at similar indoor and outdoor conditions, likely reflecting cultural factors. Unlike air-conditioned buildings, no cutoff temperature is observed for night-time window opening, reflecting a distinct night cooling strategy. During heatwaves, adaptive behaviors are adopted, yet the potential for improvement averages 40 % and ranges from 15 % to 75 % across dwellings. The largest potential of improvement lies in closing windows during the day when outdoor temperatures exceed indoor ones, whereas heat-mitigation practices are more consistently adopted at night.These findings provide a foundation for developing needed, more realistic occupant behavior models for French residential context during summer and heatwave. These results provide guidance for future awareness campaigns promoting passive heat-mitigation practices of occupants, emphasizing their importance
First intercomparison of 241Am activity measurements using primary methods including magnetic micro-calorimeters
No full textInternational audienceLow-temperature detectors, such as Magnetic Micro-calorimeters (MMCs), exhibit several characteristics that make them strong candidates for primary activity standardization of various radionuclides. As a relatively new technique, however, many aspects of MMC-based measurements still require validation. For this purpose, ²⁴¹Am was selected to conduct an intercomparison of activity measurements between MMCs and other well-established conventional methods. The alpha-particle emitter ²⁴¹Am is well-suited to such comparisons, as it can be standardized with low uncertainty using a variety of techniques, including defined solid angle counting, coincidence counting, ionization chambers, and liquid scintillation counting (LSC). A key challenge in this context is the preparation of sources compatible with both MMCs and traditional standardization methods. An 241Am source was prepared by electro-precipitation in a specially designed geometry compatible with both multi-channel MMC spectrometry and conventional methods. This source was measured by four metrology institutes - LNE-LNHB, CIEMAT, CHUV, and PTB - using different primary methods. Subsequently, the original source was divided into 21 secondary sources, which were integrated into 11 absorbers of a multi-channel MMC spectrometer for the final activity determination.Activity measurements using MMCs will be presented, along with the results of the intercomparison between different laboratories and techniques. The reported uncertainties are relatively high, in the range of a few percent, due to the rather low activity of the source and a potential loss of activity during the exercise. However, this first intercomparison provides insights and opportunities for improvement, which will be implemented in the future
An all-Mach cell-centered multi-dimensional nite volume numerical scheme for the Euler equations
No full textInternational audienceIn the context of the numerical approximation of Euler equations, great efforts have been devoted to developing schemes that can accurately reproduce solutions in low Mach number ows. Solutions of classic Finite Volume (FV) schemes are usually plagued by an excessive diusion as the numerical scheme is not consistent with the limit equations for the Mach number that tends to zero. Instead, a numerical scheme that satises such a property is called Asymptotic-Preserving (AP). In this paper, we propose an AP FV scheme for the multi-dimensional Euler equations. In classic FV methods, the numerical approximation of the face ux is obtained by means of a two-state 1D approximate Riemann Solver (RS) in the normal direction to the face. Here, we rely on a node-based ux approximation that exploits a particular RS involving a nodal quantity which depends on all the cells around a given node. Such an idea has been exploited by Barsukow et al. (2023) for the linear acoustic equations. Their method is vorticity-preserving, but its extension to the Euler equations proved to be far from trivial. For such a reason, a change of perspective is needed in the denition of the RS
Tailoring aluminosilicates for optimized cesium removal through curing control strategy
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Assessment of the tritium analysis performance of a nonylphenol-ethoxylate-free liquid scintillator by interlaboratory comparison
No full textInternational audienceWith a view to using liquid scintillators compliant with the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulations, some laboratories have expressed an interest in testing the ProSafe LT+ , a liquid scintillator without nonylphenol-ethoxylates (NPE). In order to evaluate the impact of using this new liquid on the analysis results, the CETAMA consortium organised two interlaboratory comparisons. Two ranges of tritium activity were selected to meet the needs of environmental and waste monitoring. 23 laboratories took part in these exercises, comparing results obtained with Prosafe LT+ to those obtained with NPE-containing liquid scinitllators. From the results it was seen that the background and the background noise obtained with the nonylphenol-ethoxylates-free liquid scintillator are not significantly different from that of the usual liquid scintillator, whether for the waste or environmental domain, over short (15 min) or long (200 min) counting times. Furthermore, the decision threshold and the detection limit values estimated with ProSafe LT+ were no different from those of usual scintillators. However, for the measurement of samples, and particularly for samples with a tritium activity above 15 Bq/kg, the ProSafe LT+ presented a reduced measurement quality compared to the nonylphenol-ethoxylates-containing LS i.e. the measurement uncertainty obtained with ProSafe LT+ is systematically higher. In light of the results obtained through this study, the authors recommend the use of the ProSafe LT+ with the proviso that the deterioration in measurement uncertainty be taken into account and found to be compatible with a laboratory’s individual needs
Understanding Charge Radii with Machine Learning: Discovering Physics Expressions
No full textInternational audienceWe introduce a robust, interpretable machine learning (ML) framework that combines numerical regression for high-accuracy predictions with symbolic regression to uncover the underlying physics. This hybrid approach effciently derives analytical expressions by leveraging the smoothed predictions of optimized ML models, a significant acceleration over direct symbolic regression on raw experimental data. We apply this framework, as an example, to nuclear charge radii across the nuclear chart, notably including light nuclei that are often excluded from such studies. We employ Light Gradient Boosting Machine (LGBM) and Gaussian Process Regression (GPR) models to map correlations between charge radii and key physical features: mass and proton number dependencies, total binding energy, and for the first time, the pairing gap. Our models are rigorously trained using four-fold cross-validation with automated hyperparameter optimization, ensuring robustness and generalizability, which is critical for the typically small and skewed datasets in nuclear physics. Finally, we distill the knowledge from the initial LGBM and GPR models into simplified, interpretable mathematical expressions via symbolic regression, white-boxing these ML models. The derived formulas provide physical insights comparable to traditional many-body models and demonstrate a powerful pathway for physics expression discovery guided by ML
Autoantibodies neutralizing type I IFNs in patients with fulminant herpes simplex virus hepatitis
No full textInternational audienceFulminant viral hepatitis (FVH) is a devastating condition caused by hepatotropic viruses such as hepatitis A virus (HAV), hepatitis B virus (HBV), and HSV-1/2. We studied 149 FVH patients (73 males and 76 females, aged 1–76) for blood autoantibodies (auto-Abs) neutralizing type I interferons (IFNs; IFN-α2, -β, -ω). Six of 16 (37.5%) HSV-triggered FVH patients carried such auto-Abs on admission, including three with a previously known autoimmune disease. These patients contrasted with 133 HAV- (n = 46) or HBV-triggered (n = 87) patients, none of whom had such detectable auto-Abs. Odds ratios for HSV-triggered FVH in individuals with auto-Abs ranged from 35.3 (95% CI: 13.0–96.2; P < 10–7) for those neutralizing only 100 pg/ml IFN-α/ω to 1,895 (CI: 448.5–8,002; P < 10–12) for those neutralizing both IFN-α and IFN-ω at 10 ng/ml. Over one third of HSV-triggered FVH cases in this international cohort were due to preexisting auto-Abs. This finding highlights auto-Abs against type I IFNs as a major determinant of HSV-FVH and paves the way for targeted preventive or therapeutic interventions