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Euclid preparation. Simulations and nonlinearities beyond CDM. 2. Results from non-standard simulations
No full textInternational audienceThe Euclid mission will measure cosmological parameters with unprecedented precision. To distinguish between cosmological models, it is essential to generate realistic mock observables from cosmological simulations that were run in both the standard -cold-dark-matter (CDM) paradigm and in many non-standard models beyond CDM. We present the scientific results from a suite of cosmological N-body simulations using non-standard models including dynamical dark energy, k-essence, interacting dark energy, modified gravity, massive neutrinos, and primordial non-Gaussianities. We investigate how these models affect the large-scale-structure formation and evolution in addition to providing synthetic observables that can be used to test and constrain these models with Euclid data. We developed a custom pipeline based on the Rockstar halo finder and the nbodykit large-scale structure toolkit to analyse the particle output of non-standard simulations and generate mock observables such as halo and void catalogues, mass density fields, and power spectra in a consistent way. We compare these observables with those from the standard CDM model and quantify the deviations. We find that non-standard cosmological models can leave significant imprints on the synthetic observables that we have generated. Our results demonstrate that non-standard cosmological N-body simulations provide valuable insights into the physics of dark energy and dark matter, which is essential to maximising the scientific return of Euclid
Hydrated electron and hydroxyl radical end-of-track yields under proton beam in water
No full textInternational audienceThis article reports on the local variations of the average yields of hydrated electron and • OH induced by 62-MeV proton beams within the final 10 mm of their propagation in liquid water. The dose rate was at least 30 Gy/s in the Bragg peak. The yields were determined by conducting in-situ and real-time acquisitions along the beam track using scavengers in solution, which produce either a fluorescence light or a UV-visible light absorbance. We used Resazurin and AmplexRed as scavengers, that respectively react with the hydrated electron and • OH to form the fluorescent Resorufin. We also performed absorption measurements with the ferro/ferricyanide system to study the combined yields involving these two radicals. Proton irradiations revealed a minimum value of 2.2 × 10 -7 mol/J for • OH yields measured with the ferrocyanide system in the Bragg peak. Yields of the hydrated electron and • OH obtained by fluorescence were significantly lower, probably due to both the dose rate effect that degrades the Resorufin fluorescence and the time resolution limit of the detection. For both absorbance and fluorescence measurements, the yields partially recovered in the distal part of the Bragg peak. The origin of this behavior is difficult to explain. We suggest that it might be related to the longitudinal straggling of the beam associated with the complex track structures found in and after the Bragg peak.</div
Quels leviers pour des trajectoires d’adaptation aux risques côtiers ? L’exemple de la région Occitanie
No full textInternational audienceCet article vise à identifier les leviers facilitant la mise en place d’une action publique progressive en termes de trajectoires d’adaptation face au changement climatique sur le littoral. Il est basé sur 18 entretiens et diverses observations menés dans le cadre d’un projet pluridisciplinaire en région Occitanie. Les principaux leviers identifiés concernent les représentations, les modes de gouvernance et les outils de l’ingénierie territoriale. Plus généralement, l’article met en avant l’importance des effets d’apprentissages collectifs, et de la structuration d’une capacité de pilotage par les acteurs de l’ingénierie territoriale
Acceptation de l’usage de l’échographie en cabinet de médecine générale dans le département des Alpes-Maritimes
No full textIntroduction and objective: the doctor-patient relationship is evolving towards a more participatory approach, where patients are playing an increasingly important role in the organization of care. Clinical ultrasound, already integrated into several medical specialties, could address these new demands by improving diagnostic accessibility in general practice. However, its use remains limited in France due to unclear regulatory frameworks and a lack of uniform training. Our study aims to assess the level of acceptance of ultrasound in general practice among the population of the Alpes-Maritimes and to determine the proportion of people in favor of this practice.Materials and methods: this is an observational, cross-sectional, and quantitative study conducted through an anonymous online self-questionnaire. The calculated sample size was 385 participants to ensure external validity. The participants (≥ 15 years old, residing ≥ 6 months/year in the Alpes-Maritimes, French-speaking, without legal protection) were categorized according to an acceptance score (Likert 0-10), with an optimal threshold determined by receiver operating characteristic (ROC) analysis. The data were analyzed using appropriate statistical tests.Results: among the 403 participants, 75.93% are in favor of ultrasound in general practice, compared to 24.07% who are opposed. The determined threshold (score ≥ 55) shows a sensitivity of 89.7% and a specificity of 77.1% (AUC = 0.866). No significant impact of age, socio-professional category, or ultrasound experience was observed, but a trend in favor of the female gender (p = 0.041) was noted. The main indications for ultrasound are the abdomen (63.03%), the urogenital system (65.76%), and musculoskeletal pathologies (61.29%).Discussion: hte high acceptance rate of ultrasound in general practice reflects the evolution of patient expectations towards more integrated care. However, its development is hindered by the lack of structured training and official recommendations. The limitations of the study include selection bias and limited statistical power. The gradual integration of ultrasound into primary care could draw inspiration from training models in cardiology and emergency medicine. Further reflection and studies on the creation of an educational program starting from the medical curriculum seem necessary.Introduction et objectif : la relation médecin-patient évolue vers une approche plus participative, où les patients jouent un rôle croissant dans l’organisation des soins. L’échographie clinique, déjà intégrée dans plusieurs spécialités médicales, pourrait répondre à ces nouvelles exigences en améliorant l’accessibilité au diagnostic en médecine générale. Cependant, son utilisation reste limitée en France en raison d’un cadre réglementaire flou et d’un manque de formation homogène. Notre étude vise à évaluer le niveau d’acceptation de l’échographie en médecine générale dans la population des Alpes-Maritimes et déterminer la proportion de personnes favorables à cette pratique.Matériel et méthode : il s’agit d’une étude observationnelle, transversale et quantitative, menée via un auto-questionnaire en ligne anonyme. La taille d’échantillon calculée était de 385 participants pour garantir la validité externe. Les participants (≥ 15 ans, résidant ≥ 6 mois/an dans les Alpes-Maritimes, francophones, sans protection juridique) ont été classés selon un score d’acceptation (Likert 0-10), avec un seuil optimal déterminé par analyse de la fonction d'efficacité du récepteur, (ROC). Les données ont été analysées à l’aide de tests statistiques adaptés.Résultats : parmi les 403 participants, 75,93 % sont favorables à l’échographie en médecine générale, contre 24,07 % défavorables. Le seuil déterminé (score ≥ 55) montre une sensibilité de 89,7 % et une spécificité de 77,1 % (AUC = 0,866). Aucun impact significatif de l’âge, de la catégorie socio-professionnelle ou de l’expérience échographique n’est observé, mais une tendance en faveur du genre féminin (p = 0,041) est notée. Les principales indications concernent l’abdomen (63,03 %), l’appareil uro-génital (65,76 %) et les pathologies musculosquelettiques (61,29 %).Discussion : la proportion d’acceptation élevée de l’échographie en médecine générale reflète l’évolution des attentes des patients vers une prise en charge plus intégrée. Toutefois, son développement est freiné par l’absence de formation structurée et de recommandations officielles. Les limites de l’étude incluent un biais de sélection et une puissance statistique limitée. L’intégration progressive de l’échographie en soins primaires pourrait s’inspirer des modèles de formation en cardiologie et médecine d’urgence. Une réflexion et des études complémentaires sur la création d’un programme d’enseignement dès le cursus médical semble nécessaires
Hasards de la naissance ? Devenir Français par le « droit du sol »
No full textInternational audienceLa naissance sur le sol français et, dans son sillage, la détermination de la nationalité d’un individu ne seraient-elles pas une vaste loterie ? « Si je savais une chose utile à ma nation qui fût ruineuse à une autre, je ne la proposerais pas à mon prince, parce que je suis homme avant d’être Français, (ou bien) parce que je suis nécessairement homme, et que je ne suis Français que par hasard », écrivait ainsi Montesquieu. Comment, au fil des siècles, la filiation, la résidence et d’autres critères sont-ils venus s’adjoindre au « droit du sol » pour conditionner l’accès à la nationalité
Kalliope sings rock and metal
No full textInternational audienceAsteroid (22) Kalliope is the densest known asteroid in the main belt, with a density of g cm, suggesting that it is differentiated. Kalliope has recently been identified as the parent body of a family of collisional fragments, which is located in the so-called 'pristine zone' of the outer main belt, between 2.825 and 2.955 au. Kalliope's spectroscopic classification has been uncertain, but it has been broadly associated with iron meteorites. We combined visible reflectance spectra from the Gaia Data Release 3, visible SDSS spectrophotometry, and new near-infrared spectroscopic observations from the SpeX instrument at NASA's Infrared Telescope Facility for 22 Kalliope family members, which were mostly classified as X or Xk-types. Considering the spectral slope and 0.9 absorption band variations, we divided the family members into three spectral groups. By analysing the spectra and geometric visible albedo data, we identified the best matches for Kalliope family members as iron and pallasite meteorites. The absence of crustal material among family members makes the nature of Kalliope's parent body unclear, whether it was a fully or partially differentiated planetesimal and whether it originated in the inner or outer Solar system
exoALMA. XV. Interpreting the Height of CO Emission Layer
No full textInternational audienceThe availability of exquisite data and the development of new analysis techniques have enabled the study of emitting heights in protoplanetary disks. In this paper, we introduce a simple model linking the emitting height of CO to the disk surface density and temperature structure. We then apply the model to measurements of the emitting height and disk temperature conducted as part of exoALMA, integrated with additional legacy measurements from the MAPS Large Programme, to derive CO column densities and surface density profiles (assuming a CO abundance) for a total of 14 disks. A unique feature of the method we introduce to measure surface densities is that it can be applied to optically thick observations, rather than optically thin as conventionally done. While we use our method on a sample of well-studied disks where temperature structures have been derived using two emission lines, we show that reasonably accurate estimates can be obtained also when only one molecular transition is available. With our method, we obtain independent constraints from 12CO and 13CO, and we find they are in general good agreement using the standard 12C/13C isotopic ratio. The masses derived from our method are systematically lower compared with the values derived dynamically from the rotation curve if using an interstellar matter (ISM) CO abundance, implying that CO is depleted by a median factor ∼20 with respect to the ISM value, in line with other works that find that CO is depleted in protoplanetary disks
Ageing exacerbates the adverse effects of respiratory muscle fatigue on vascular function, locomotor muscle fatigue and exercise performance in males
No full textInternational audienceThis study investigated the effect of respiratory muscle fatigue on cardiovascular function, locomotor muscle fatigue and exercise performance in young and master athletes, a model of successful ageing. Ten young male (YA, 27.4 ± 4.4 years) and 11 male master endurance athletes (MA, 65.0 ± 5.1 years) performed, on separate days, two constant workload cycling tests at 90% of peak power to exhaustion (CWT) following a fatiguing inspiratory loading task at 60% (ILT 60% ) and a sham task at 2% (ILT 2% ) of their maximal inspiratory pressure. On a third day, the sham task was replicated but CWT was interrupted at the time equal to that performed during CWT ILT60% (CWT ILT2%-ISO ). Quadriceps fatigue was assessed by changes in maximal voluntary isometric contraction (MVC), potentiated twitch force (QT SINGLE ) and voluntary activation (VA) from 15 s to 15 min post-exercise. Mean arterial pressure (MAP) was measured using finger pulse photoplethysmography. Blood flow (Q˙L) and limb vascular conductance (LVC) were measured using Doppler ultrasound.During ILT 60% , MA demonstrated reduced Q˙L (P = 0.036), a greater increase in MAP (P < 0.001) and a larger decrease in LVC (P = 0.044) compared to YA. During CWT ILT60% , MA experienced a larger decrease in time to exhaustion (-39.7 ± 14.0%) than YA (-15.5 ± 13.9%, P = 0.010). Exercise-induced reductions in MVC and QT SINGLE (both P < 0.039) were also more pronounced during CWT ILT60% compared to CWT ILT2%-ISO in MA. Ageing exacerbates the adverse effects of respiratory muscle fatigue on limb vascular function and locomotor muscle fatigue during subsequent exercise, resulting in greater impairments in exercise performance.</p
Spiking Neural Models for Decision-Making Tasks with Learning
No full textIn cognition, response times and choices in decision-making tasks are commonly modeled using Drift Diffusion Models (DDMs), which describe the accumulation of evidence for a decision as a stochastic process, specifically a Brownian motion, with the drift rate reflecting the strength of the evidence. In the same vein, the Poisson counter model describes the accumulation of evidence as discrete events whose counts over time are modeled as Poisson processes, and has a spiking neurons interpretation as these processes are used to model neuronal activities. However, these models lack a learning mechanism and are limited to tasks where participants have prior knowledge of the categories. To bridge the gap between cognitive and biological models, we propose a biologically plausible Spiking Neural Network (SNN) model for decision-making that incorporates a learning mechanism and whose neurons activities are modeled by a multivariate Hawkes process. First, we show a coupling result between the DDM and the Poisson counter model, establishing that these two models provide similar categorizations and reaction times and that the DDM can be approximated by spiking Poisson neurons. To go further, we show that a particular DDM with correlated noise can be derived from a Hawkes network of spiking neurons governed by a local learning rule. In addition, we designed an online categorization task to evaluate the model predictions. This work provides a significant step toward integrating biologically relevant neural mechanisms into cognitive models, fostering a deeper understanding of the relationship between neural activity and behavior
Gromov-Wasserstein Bound between Reeb and Mapper Graphs
No full textSince its introduction as a computable approximation of the Reeb graph, the Mapper graph has become one of the most popular tools from topological data analysis for performing data visualization and inference. However, finding an appropriate metric (that is, a tractable metric with theoretical guarantees) for comparing Reeb and Mapper graphs, in order to, e.g., quantify the rate of convergence of the Mapper graph to the Reeb graph, is a difficult problem. While several metrics have been proposed in the literature, none is able to incorporate measure information, when data points are sampled according to an underlying probability measure. The resulting Reeb and Mapper graphs are therefore purely deterministic and combinatorial, and substantial effort is thus required to ensure their statistical validity. In this article, we handle this issue by treating Reeb and Mapper graphs as metric measure spaces. This allows us to use Gromov-Wasserstein metrics to compare these graphs directly in order to better incorporate the probability measures that data points are sampled from. Then, we describe the geometry that arises from this perspective, and we derive rates of convergence of the Mapper graph to the Reeb graph in this context. Finally, we showcase the usefulness of such metrics for Reeb and Mapper graphs in a few numerical experiments