766 results match your criteria: "centre d'études de Saclay[Affiliation]"

We propose a neural networks method to estimate extreme Expected Shortfall, and even more generally, extreme conditional tail moments as functions of confidence levels, in heavy-tailed settings. The convergence rate of the uniform error between the log-conditional tail moment and its neural network approximation is established leveraging extreme-value theory (in particular the high-order condition on the distribution tails) and using critically two activation functions (eLU and ReLU) for neural networks. The finite sample performance of the neural network estimator is compared to bias-reduced extreme-value competitors using synthetic heavy-tailed data.

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Neuroimaging Insights into Brain Mechanisms of Early-onset Restrictive Eating Disorders.

medRxiv

November 2024

Institut Pasteur, Université de Paris, CNRS UMR 3571, Human Genetics and Cognitive Functions, 25 rue du Dr. Roux, Paris, France.

Article Synopsis
  • Early-onset restrictive eating disorders (rEO-ED), including early-onset anorexia nervosa (EO-AN) and avoidant restrictive food intake disorders (ARFID), have unknown impacts on brain development.
  • A study comparing brain features through MRI in children under 13 with EO-AN, ARFID, and typically developing peers revealed differing brain structures despite similar BMI, indicating unique brain mechanisms for each disorder.
  • Findings suggest EO-AN is linked to thinner cortex structures, while ARFID patients showed reduced surface area and subcortical volume, highlighting the need for further research on the relationship between low BMI and neurodevelopmental impacts in eating disorders.
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On the Origin of fMRI Species.

J Magn Reson Imaging

November 2024

NeuroSpin, Frédéric Joliot Institute for Life Sciences (Commissariat à l'Energie Atomique, CEA), Centre d'études de Saclay, Paris-Saclay University, Gif-sur-Yvette, France.

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ECM1 attenuates hepatic fibrosis by interfering with mediators of latent TGF-β1 activation.

Gut

October 2024

Department of Medicine II, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany

Objective: Extracellular matrix protein 1 (ECM1) serves as a gatekeeper of hepatic fibrosis by maintaining transforming growth factor-β1 (TGF-β1) in its latent form. ECM1 knockout (KO) causes latent (L) TGF-β1 activation, resulting in hepatic fibrosis with rapid mortality. In chronic liver disease (CLD), ECM1 decreases with increasing CLD severity.

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Ribosome biogenesis is a complex process requiring multiple precursor ribosomal RNA (rRNA) cleavage steps. In archaea, the full set of ribonucleases (RNases) involved in rRNA processing remains to be discovered. A previous study suggested that FAU-1, a conserved protein containing an RNase G/E-like protein domain fused to a domain of unknown function (DUF402), acts as an RNase in archaea.

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The Nucleic Acid InfraRed Data Bank (NAIRDB) serves as a comprehensive public repository dedicated to the archival and free distribution of Fourier transform infrared (FTIR) spectral data specific to nucleic acids. This database encompasses a collection of FTIR spectra covering diverse nucleic acid molecules, including DNA, RNA, DNA/RNA hybrids and their various derivatives. NAIRDB covers details of the experimental conditions for FTIR measurements, literature links, primary sequence data, information about experimentally determined structures for related nucleic acid molecules and/or computationally modeled 3D structures.

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Article Synopsis
  • The Letter reports the most accurate measurement so far of the matter-antimatter imbalance during Pb-Pb collisions at a high energy level of 5.02 TeV.
  • It utilizes the Statistical Hadronization framework to determine precise values for the electric charge and baryon chemical potentials, μ_{Q} and μ_{B}.
  • The analysis of antiparticle-to-particle yield ratios shows that the collisions create a system that is generally baryon-free and electrically neutral at midrapidity.
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Realization of a gas puff imaging system on the Wendelstein 7-X stellarator.

Rev Sci Instrum

September 2024

Laboratoire de Physique des Plasmas, Ecole Polytechnique-CNRS-Univ Paris-Sud-UPMC, Rte de Saclay, 91128 Palaiseau, France.

A system for studying the spatiotemporal dynamics of fluctuations in the boundary of the W7-X plasma using the "Gas-Puff Imaging" (GPI) technique has been designed, constructed, installed, and operated. This GPI system addresses a number of challenges specific to long-pulse superconducting devices, such as W7-X, including the long distance between the plasma and the vacuum vessel wall, the long distance between the plasma and diagnostic ports, the range of last closed flux surface (LCFS) locations for different magnetic configurations in W7-X, and management of heat loads on the system's plasma-facing components. The system features a pair of "converging-diverging" nozzles for partially collimating the gas puffed locally ≈135 mm radially outboard of the plasma boundary, a pop-up turning mirror for viewing the gas puff emission from the side (which also acts as a shutter for the re-entrant vacuum window), and a high-throughput optical system that collects visible emission resulting from the interaction between the puffed gas and the plasma and directs it along a water-cooled re-entrant tube directly onto the 8 × 16 pixel detector array of the fast camera.

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The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high p_{T}) hadron trigger in proton-proton and central Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions.

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We propose the angular distribution of lepton pairs produced in ultrarelativistic heavy-ion collisions as a probe of thermalization of the quark-gluon plasma. We focus on dileptons with invariant masses large enough that they are produced through quark-antiquark annihilation in the early stages of the collision. The angular distribution of the lepton in the rest frame of the pair then reflects the angular distribution of quark momenta.

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K^{+}K^{-} pairs may be produced in photonuclear collisions, either from the decays of photoproduced ϕ(1020) mesons or directly as nonresonant K^{+}K^{-} pairs. Measurements of K^{+}K^{-} photoproduction probe the couplings between the ϕ(1020) and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere.

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In this work, we introduce a compartmental model of ovarian follicle development all along lifespan, based on ordinary differential equations. The model predicts the changes in the follicle numbers in different maturation stages with aging. Ovarian follicles may either move forward to the next compartment (unidirectional migration) or degenerate and disappear (death).

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For air quality management, while numerical tools are mainly evaluated to assess their performances on absolute concentrations, this study assesses the impact of their settings on the robustness of model responses to emission reduction strategies for the main criteria pollutants. The effect of the spatial resolution and chemistry schemes is investigated. We show that whereas the spatial resolution is not a crucial setting (except for NO), the chemistry scheme has more impact, particularly when assessing hourly values of the absolute potential of concentrations.

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Article Synopsis
  • - This Letter discusses the measurement of ridge yields from charged hadron angular correlations in proton-proton collisions at a high energy of 13 TeV, specifically within certain pseudorapidity and transverse momentum ranges.
  • - The research extends ridge yield measurements to low charged-particle multiplicity regions, where typically a strong interacting medium is not expected to form during collisions.
  • - Findings indicate that ridge yields in pp collisions are significantly higher than those observed in e^{+}e^{-} collisions, suggesting that processes in e^{+}e^{-} annihilations do not significantly influence long-range correlations in proton-proton interactions.
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Article Synopsis
  • The ALICE detector measured the cross section for incoherent photonuclear production of J/ψ vector mesons, focusing on the Mandelstam |t| variable, during ultraperipheral collisions of Pb nuclei at a very high energy of 5.02 TeV.
  • The measurement was conducted within a rapidity interval of |y|<0.8 and covers a specific range of Bjorken-x values.
  • Analysis showed that models without quantum fluctuations in the gluon density predicted a much steeper |t|-dependence than observed, but including these fluctuations improved the models' alignment with the data.
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[F]2-fluoro-2-deoxy-sorbitol ([F]FDS) PET imaging repurposed for quantitative estimation of blood-brain barrier permeability in a rat model of Alzheimer's disease.

Ann Pharm Fr

September 2024

Service hospitalier Frédéric-Joliot, laboratoire d'imagerie biomédicale multimodale (BioMaps), Inserm, CNRS, CEA, université Paris-Saclay, 91401 Orsay, France. Electronic address:

Numerous studies suggest that blood-brain barrier (BBB) dysfunction may contribute to the progression of Alzheimer's disease (AD). Clinically available neuroimaging methods are needed for quantitative "scoring" of BBB permeability in AD patients. [F]2-fluoro-2-deoxy-sorbitol ([F]FDS), which can be easily obtained from simple chemical reduction of commercial [F]2-fluoro-2-deoxy-glucose ([F]FDG), was investigated as a small-molecule marker of BBB permeability, in a pre-clinical model of AD using in vivo PET imaging.

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A stochastic model for neural progenitor dynamics in the mouse cerebral cortex.

Math Biosci

June 2024

Institut Polytechnique de Paris, Inria, Centre de Mathématiques Appliquées, 91120, Palaiseau, France. Electronic address:

We have designed a stochastic model of embryonic neurogenesis in the mouse cerebral cortex, using the formalism of compound Poisson processes. The model accounts for the dynamics of different progenitor cell types and neurons. The expectation and variance of the cell number of each type are derived analytically and illustrated through numerical simulations.

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The gut microbiota plays a crucial role in health and is significantly modulated by human diets. In addition to Western diets which are rich in proteins, high-protein diets are used for specific populations or indications, mainly weight loss. In this study, we investigated the effect of protein supplementation on , a Gram-negative gut symbiont.

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ψ(2S) Suppression in Pb-Pb Collisions at the LHC.

Phys Rev Lett

January 2024

INFN, Sezione di Pavia, Pavia, Italy.

The production of the ψ(2S) charmonium state was measured with ALICE in Pb-Pb collisions at sqrt[s_{NN}]=5.02  TeV, in the dimuon decay channel. A significant signal was observed for the first time at LHC energies down to zero transverse momentum, at forward rapidity (2.

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Mathematical modeling of adipocyte size distributions: Identifiability and parameter estimation from rat data.

J Theor Biol

March 2024

Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratory of Computational and Quantitative Biology UMR 7238, 75005 Paris, France; Sorbonne Université, CNRS, Université de Paris, Laboratoire Jacques-Louis Lions UMR 7598, 75005 Paris, France. Electronic address:

Fat cells, called adipocytes, are designed to regulate energy homeostasis by storing energy in the form of lipids. Adipocyte size distribution is assumed to play a role in the development of obesity-related diseases. These cells that do not have a characteristic size, indeed a bimodal size distribution is observed in adipose tissue.

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Biological data show that the size distribution of adipose cells follows a bimodal distribution. In this work, we introduce a Lifshitz-Slyozov type model, based on a transport partial differential equation, for the dynamics of the size distribution of adipose cells. We prove a new convergence result from the related Becker-Döring model, a system composed of several ordinary differential equations, toward mild solutions of the Lifshitz-Slyozov model using distribution tail techniques.

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Mutation of AtPME2, a pH-Dependent Pectin Methylesterase, Affects Cell Wall Structure and Hypocotyl Elongation.

Plant Cell Physiol

February 2024

UMRT INRAE 1158 BioEcoAgro-BIOPI Plant Biology and Innovation, University of Picardie, 33 Rue St Leu, Amiens 80039, France.

Pectin methylesterases (PMEs) modify homogalacturonan's chemistry and play a key role in regulating primary cell wall mechanical properties. Here, we report on Arabidopsis AtPME2, which we found to be highly expressed during lateral root emergence and dark-grown hypocotyl elongation. We showed that dark-grown hypocotyl elongation was reduced in knock-out mutant lines as compared to the control.

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From Black Holes Entropy to Consciousness: The Dimensions of the Brain Connectome.

Entropy (Basel)

December 2023

NeuroSpin, Frédéric Joliot Institute for Life Sciences (Commissariat à l'Energie Atomique, CEA), Centre d'Études de Saclay, Paris-Saclay University, Bâtiment 145, 91191 Gif-sur-Yvette, France.

It has been shown that the theory of relativity can be applied physically to the functioning brain, so that the brain connectome should be considered as a four-dimensional spacetime entity curved by brain activity, just as gravity curves the four-dimensional spacetime of the physical world. Following the most recent developments in modern theoretical physics (black hole entropy, holographic principle, AdS/CFT duality), we conjecture that consciousness can naturally emerge from this four-dimensional brain connectome when a fifth dimension is considered, in the same way that gravity emerges from a 'flat' four-dimensional quantum world, without gravitation, present at the boundaries of a five-dimensional spacetime. This vision makes it possible to envisage quantitative signatures of consciousness based on the entropy of the connectome and the curvature of spacetime estimated from data obtained by fMRI in the resting state (nodal activity and functional connectivity) and constrained by the anatomical connectivity derived from diffusion tensor imaging.

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Introduction: Fetal alcohol spectrum disorders (FASD) range from fetal alcohol syndrome (FAS) to non-syndromic forms (NS-FASD). The neuroanatomical consequences of prenatal alcohol exposure are mainly the reduction in brain size, but also focal abnormalities such as those of the corpus callosum (CC). We previously showed a narrowing of the CC for brain size, using manual measurement and its usefulness to improve diagnostic certainty.

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Article Synopsis
  • Understanding how parton mass and Casimir color factors affect heavy quark emissions is key to studying quantum chromodynamics (QCD).
  • This research presents the first experimental constraint on the charm-quark splitting function, obtained through measurements in proton-proton collisions at 13 TeV.
  • Findings indicate that charm quarks show a steeper splitting function compared to gluons and light quarks, experiencing fewer emissions with a lower likelihood of large-angle emissions.
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