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Double Debiased Machine Learning for Mediation Analysis with Continuous Treatments
No full textInternational audienceUncovering causal mediation effects is of significant value to practitioners seeking to isolate the direct treatment effect from the potential mediated effect. We propose a double machine learning (DML) algorithm for mediation analysis that supports continuous treatments. To estimate the target mediated response curve, our method uses a kernel-based doubly robust moment function for which we prove asymptotic Neyman orthogonality. This allows us to obtain asymptotic normality with nonparametric convergence rate while allowing for nonparametric or parametric estimation of the nuisance parameters. We then derive an optimal bandwidth strategy along with a procedure for estimating asymptotic confidence intervals. Finally, to illustrate the benefits of our method, we provide a numerical evaluation of our approach on a simulation along with an application to real-world medical data to analyze the effect of glycemic control on cognitive functions.</div
Flexibilité, résilience, normes, limites : démarche antécédente et a priori sur le droit
No full textInternational audienc
Vidéos pédagogiques sur les formes du tai chi Sun: Liens vidéos en complément de l’ouvrage « 2. Formes et applications en tai chi Sun »
No full text16 vidéos d’apprentissage des mouvements de la forme des 73 postures du style Sun de tai chi chuan. Accessibles sur YouTube : Durée totale : environ 150 minutesUne tradition vivanteLes anciens traitésEntrer dans les formesMatrice et structureTransfert au quotidienForme des 73 postures Su
Vidéos pédagogiques sur les fondements du style Yang: Liens vidéos en complément de l’ouvrage « Les fondamentaux du style Yang de tai chi »
No full text15 vidéos d’apprentissage des principes et des techniques principales du style Yang de tai chi chuan. Accessibles sur YouTube : Durée totale : environ 5 heures.Exercices préparatoiresQi gong (travail du souffle)Nei Gong (travail intérieur)Wu gong du style Yang (étude des principes)Ba fa (pratique des techniques principales)Forme des 10 postures YangTravail posturalExercices respiratoiresUtilisation de l’imagination activeCapture du mouvement (Université de Mons
Fair leadership and job satisfaction: insights from SMEs
No full textInternational audienceThis study examines how fairness and leadership affect job satisfaction in Lebanese small and medium-sized enterprises (SMEs), drawing on social exchange theory. Analysing responses from 1,127 participants using structural equation modelling, the findings show that interactional justice or fair and respectful treatment by leaders positively influences leader-member exchange and job satisfaction, reinforcing the importance of quality leadership. Contrary to expectations, procedural justice or fairness in processes does not directly improve leader-member relationships, hinting that specific situational factors might play a more crucial role. Furthermore, the anticipated mediating role of leader-member exchange between procedural justice and job satisfaction was not supported, nor was gender found to significantly affect these relationships. These results suggest the need for SMEs to focus on personalised leadership and fair communication to enhance employee relations and satisfaction, regardless of gender. The study highlights the significance of adopting inclusive practices and effective crisis management strategies that prioritise both procedural and interactional justice to build organisational resilience
High-mountain groundwater quality affected by natural acid drainage
No full textInternational audienceGroundwater in high-mountain areas like the Central Chilean Andes is a crucial freshwater source for downstream communities. However, its pristine reputation masks a hidden threat when metallogenic systems exist: Natural Acid Drainage (NAD). This study comprehensively investigates the hydrogeological systems and the impact of NAD on groundwater quality in this copper-rich high-altitude region from an interdisciplinary approach. Specifically, the study area lies in the El Arpa Valley, a site with minimal human influence. Isotopic and hydrogeochemical analyses of groundwater, surface water, and snow samples revealed a groundwater origin between 2900 and 3300 m a.s.l. and the influence of fractures and gullies on recharge mechanisms. Physicochemical parameters exhibit increasing mineralisation downstream (118 to 714 µS/cm) with a pH range of 3.86–7.01. SO42--Ca2+ facies and elevated aluminium (4.59–6349.31 ppb), iron (1.00–7003.24 ppb), and manganese (1.25–1098.41 ppb) contents characterise groundwater composition. Rock geochemistry and mineralogy show that phyllic alteration overprinted by supergene processes contributes to NAD by dissolving pyrite and iron oxyhydroxides. Principal component analysis on Landsat 8 images allows for identifying potential NAD areas over 11.6 % of the high Andes. The widespread occurrence challenges the perception of pristine mountain water, emphasising the potential adverse effects on human health and infrastructure, mainly due to high manganese content (>80 ppb). Findings advance the knowledge on NAD occurrence in remote mountainous regions, urging a reassessment of water quality perceptions in the presence of geogenic pollution sources, particularly considering the current threat of climate change
PITSZI: Probing intra-cluster medium turbulence with Sunyaev–Zel’dovich imaging: Application to the triple merging cluster MACS J0717.5+3745
No full textInternational audienceTurbulent gas motions are expected to dominate the non-thermal energy budget of the intracluster medium (ICM). The measurement of pressure fluctuations from high angular resolution Sunyaev–Zel’dovich imaging opens a new avenue to study ICM turbulence, complementary to X-ray density fluctuation measures. We developed a methodological framework designed to optimally extract information on the ICM pressure fluctuation power spectrum statistics, and publicly released the associated software named PITSZI (Probing ICM Turbulence from Sunyaev–Zel’dovich Imaging). We applied this tool to the New IRAM KIDs Array (NIKA) data of the merging cluster MACS J0717.5+3745 to measure its pressure fluctuation power spectrum at high significance, and to investigate the implications for its non-thermal content. Depending on the choice of the radial pressure model and the details of the applied methodology, we measured an energy injection scale Linj ∼ 800 kpc. The power spectrum normalization corresponds to a characteristic amplitude reaching AδP/P̄(kpeak) ∼ 0.4. These results were obtained assuming that the ICM of MACS J0717.5+3745 can be described as pressure fluctuations on top of a single (smooth) halo, and were dominated by systematics due to the choice of the radial pressure model. Using simulations, we determined that fitting a radial model to the data can suppress the observed fluctuations by up to ∼50%, while a poorly representative radial model can induce spurious fluctuations, which we also quantified. Assuming standard scaling relations between the pressure fluctuations and turbulence, we find that MACS J0717.5+3745 presents a turbulent velocity dispersion σv ∼ 1200 km/s, a kinetic to kinetic plus thermal pressure fraction Pkin/Pkin + th ∼ 20%, and we estimate the hydrostatic mass bias to bHSE ∼ 0.3 − 0.4. Our results are in excellent agreement with alternative measurements obtained from X-ray surface brightness fluctuations, and in agreement with the fluctuations being adiabatic in nature
L'ouverture des données foncières, une utopie du passé ?
No full textNational audienceSe replonger dans la lecture d'Edgar Pisani rappelle tout le chemin qui a été parcouru pour l'ouverture des données foncières depuis 50 ans. À une époque où l'idée d'un grand « livre foncier » recensant l'ensemble des informations relatives à la propriété foncière était une utopie, cette ambition reposait sur un objectif fort : lutter contre la spéculation, protéger les terres agricoles et naturelles, et garantir une gestion publique juste et rationnelle du sol. Aujourd'hui, l'accès aux données foncières n'a jamais été aussi facile, mais paradoxalement, l'idéal d'une gestion collective du foncier ne semble pas être un horizon désirable pour les pouvoirs publics. Dès lors, quelle nouvelle utopie est sous-tendue par la massification contemporaine des données foncières
Sensitivity Analysis of Global Kinematics on Mantle Structure Using Automatically Generated Adjoint Thermochemical Convection Codes
No full textInternational audienceWithin the past 30 years, numerical models of mantle convection have been able to predict observations on Earth and planets, and among them tectonics. The possibility of building inverse problems in global geodynamics became concrete, and often involve the development of adjoint codes. Such tools provide efficient ways to estimate sensitivities of misfit functions relative to control parameters, like errors on predicted velocities relative to mantle 3D structure. One issue to build an adjoint code is that such code is problem specific in many cases, while forward codes are versatile. We propose here a way to build adjoint codes that are exact adjoints of forward codes through an automated process. Using the automatic differentiation translator TAF \cite{giering2003} and incorporating specific implementations for MPI communications, we generate two adjoint codes of the 3D spherical thermomechanical mantle convection code StagYY \cite{tackley2008}. We first present a benchmarking example computing the sensitivities of a thermal state to initial conditions with a 3D spherical thermochemical model. We then compute the sensitivities of present-day plate velocities relative to guessed temperature distribution in the mantle. The sensitivities reflect either the intrinsic sensitivity of the problem (sensitivity to upper mantle structure) and the errors made in reconstructing the thermal structure of the mantle (deepest mantle structure). Both codes successfully pass the rigorous and demanding gradient test, also called Taylor test. We show that our workflow for automatic generation of adjoint codes for StagYY provides a sustainable and adaptive method to engage in inverse modelling and sensitivity computations of 3D global geodynamics
