HAL Portal UPHF (Université Polytechnique Hauts-de-France)
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Mechanisms of DNA Damage Recognition by UDG and PARP1 in the Nucleosome
No full textInternational audienceThe DNA base-excision repair (BER) pathway shares the second part of its enzymatic chain with the single-strand break (SSB) repair pathway. BER is initiated by a glycosylase, such as UDG, while SSBR is initiated by the multifunctional enzyme PARP1. The very early steps in the identification of the DNA damage are crucial to the correct initiation of the repair chains, and become even more complex when considering the realistic environment of damage to the DNA in the nucleosome. We performed molecular dynamics computer simulations of the interaction between the glycosylase UDG and a mutated uracil (as could result from oxidative deamination of cytosine), and between the Zn1-Zn2 fragment of PARP1 and a simulated SSB. The model system is a whole nucleosome in which DNA damage is inserted at various typical positions along the 145-bp sequence. It is shown that damage recognition by the enzymes requires very strict conditions, unlikely to be matched by pure random search along the DNA. We propose that mechanical deformation of the DNA around the defective sites may help signaling the presence of the defect, accelerating the search process.</div
Torsional Rigidity on Metric Graphs with Delta-Vertex Conditions
No full textWe investigate the torsion function or landscape function and its integral, the torsional rigidity, of Laplacians on metric graphs subject to -vertex conditions. A variational characterization of torsional rigidity and Hadamard-type formulas are obtained, enabling the derivation of surgical principles. We use these principles to prove upper and lower bounds on the torsional rigidity and identify graphs maximizing and minimizing torsional rigidity among classes of graphs. We also investigate the question of positivity of the torsion function and reduce it to positivity of the spectrum of a particular discrete, weighted Laplacian. Additionally, we explore potential manifestations of Kohler-Jobin-type inequalities in the context of -vertex conditions
Faber-Krahn inequality for the heat content on quantum graphs via random walk expansion
No full textWe study the heat content on quantum graphs and investigate whether an analogon of the Rayleigh-Faber-Krahn inequality holds. This means that heat content at time among graphs of equal volume would be maximized by intervals (the graph analogon of balls as in the classic Rayleigh-Faber-Krahn inequality). We prove that this holds at extremal times, that is at small and at large times. For this, we employ two complementary approaches: In the large time regime, we rely on a spectral-theoretic approach, using Mercer's theorem whereas the small-time regime is dealt with by a random walk approach using the Feynman-Kac formula and Brownian motions on metric graphs. In particular, in proving the latter, we develop a new expression for the heat content as a positive linear combination of expected return times of (discrete) random walks - a formulation which seems to yield additional insights compared to previously available methods such as the celebrated Roth formula and which is crucial for our proof. The question whether a Rayleigh-Faber-Krahn inequality for the heat content on metric graphs holds at all times remains open
Millimetre wave-based neuromodulation combined with coaching improves quality of life in fibromyalgia patients: A 9-month prospective, multicenter, open, randomized, controlled trial
No full textInternational audienceBackground: This study assessed the efficacy of a therapy combining a millimeter wave emitting wristband and coaching in improving the quality of life (QoL) of Fibromyalgia (FM) patients, compared to standard care.Methods: An open, randomized clinical trial enrolled 170 patients with FM (2016 American College of Rheumatology criteria, Fibromyalgia Impact Questionnaire score ≥ 39) from 8 French pain centers, and compared Immediate versus Delayed therapy. Therapy was provided at inclusion (D0) and month three (M3) in the Immediate and Delayed groups respectively. Therapy in the Immediate group stopped from month six (M6) to month nine (M9). Randomization was stratified by center, and FM severity, allocation ratio was 1:1. The primary outcome compared the proportion of patients with a Fibromyalgia Impact Questionnaire reduction ≥ 14% (minimal clinically important difference), from D0 to M3 in both groups. Pain (Visual Analogic Scale), sleep (Pittsburg sleep quality index), anxiety and depression (Hospital Anxiety and Depression Scale), fatigue (Multidimensional Fatigue Inventory Questionnaire), patients' and clinicians' impression of change (patient global impression of change & clinician global impression of change), physical activity (Global Physical Activity Questionnaire), generic QoL (euroqol, 5 dimensions, 5 levels), pharmacological and complementary treatment intakes, and healthcare requirements were measured at M3, M6, and M9.Results: At M3, 38/69 (55.1%) and 28/78 (35.9%) patients in the Immediate and Delayed groups respectively achieved the minimal clinically important difference ( P = .021). There were also significant improvements in sleep quality, pain, anxiety, depression, general and physical fatigue in the Immediate versus the Delayed group at M3. These benefits persisted at M6.Conclusion: Our results demonstrate that combined millimeter wave-based neuromodulation and coaching improve the QoL and other symptoms of patients with FM after 3 and 6 months
Fortran Package Manager fpm
No full textPrésentation faite lors de la journée Fortran organisée par le Groupe Calcul du CNRS, le 13 juin 2025 à l'Observatoire de Paris.A l'instar d'autres langages tels que Rust, le langage Fortran dispose désormais d'un gestionnaire de paquets faisant également office d'outil de construction de projet : fpm (Fortran Package Manager). Cet outil est développé par la communauté Fortran-lang.org
A Practical Approach for Internal Energy Tuning in LDI-MS: Porous Silicon Substrates as a Case Study
No full textInternational audienceThis study presents a methodical procedure for optimizing laser desorption/ionization mass spectrometry (LDI-MS) supports using porous silicon (PSi) substrates. The approach involves the use of substituted benzyl-pyridinium salts (thermometer ions) to obtain one metric that assesses analyte fragmentation (the effective temperature of vibration). Porous silicon substrates were synthesized via electrochemical etching of p-type silicon wafers (10-20 mΩ•cm), with etching parameters adjusted to vary porosity while maintaining a layer thickness between 700 and 1200 nm. The results revealed that PSi substrates with 40-60% porosity achieved the lowest fragmentation levels. This finding was validated through the analysis of N-acetyl glucosamine, a carbohydrate, which confirmed the effective temperature trend. Further analysis involving peptides, specifically P14R and a peptide mix (Peptide Calibration Standard II, Bruker), demonstrated that the optimized PSi substrates enabled the desorption and ionization of peptides with a maximum mass at m/z 2465, corresponding to ACTH clip 1-17. These results highlight the critical role of substrate porosity in minimizing analyte fragmentation and enhancing LDI-MS performance.</div
« Les cultures méso-américaines précolombiennes dans Des Caraïbes au Mexique. Journal d’un voyageur (1934) d’Aldous Huxley »
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Analyse des objectifs de la réforme ANC n° 2022-06 et de son impact sur l'information comptable.
No full textInternational audienceAvec l'application obligatoire depuis le 0 1/01/2025 du règlement n°2022-06 de l'ANC, le normalisateur comptable français déclare poursuivre des objectifs de simplification et de modernisation des normes comptables et des documents comptables. Cet article propose d'apprécier ces objectifs à partir d'une présentation des points essentiels de la réforme, d'analyser les enjeux de cette dernière dans un contexte de convergence du PCG vers le référentiel I AS/IFRS, et enfin d'estimer l'impact de celle-ci sur l'information comptable. L'analyse des statistiques descriptives, basée sur un échantillon composé de 109 sociétés cotées sur Euronext-Growth, prévoit un impact significatif de la réforme sur le résultat d'exploitation
Caractérisation avancée des interfaces de transistors HEMT pour l'électronique de puissance : corrélation entre propriétés chimiques, structurales et électriques
No full textGallium nitride (GaN) is a well-suited material particularly for the manufacture of high-performance integrated circuits operating at high frequencies. In particular, GaN technology makes it possible to improve the power level, efficiency and compactness of HEMTs (High Electron Mobility Transistors), giving access to new functionalities for terrestrial and space telecommunication applications in the military field (radars with active antennas for target detection) and in the civilian field (5G telecommunications). However, there is still room for improvement in the performance and stability of these devices, and we need to move towards transistor even shorter gate lengths dimension. The aim of this thesis work is to investigate, using a multi-technique approach combining XPS / nano-AES / STEM-EDS and electrical measurements, the origin of the limited electrical performance of HEMTs and their degradation over time. An XPS data processing procedure is proposed to enable accurate quantification of GaN-based materials, which requires separating the N 1s contribution from the Ga LMM bulk and considering the formation of metallic gallium during profiling by ion abrasion. Localized Auger probe analysis (nano-AES) is carried out directly on transistors prepared by FIB in thin wafers, providing complementary information to the chemical and structural measurements obtained by STEM-EDX. This original approach has been successfully used to guide HEMT fabrication towards an optimized structure, and to study and understand the drift in electrical behavior under stress, linking it to a chemical and/or structural origin.Le nitrure de gallium (GaN) est un matériau particulièrement adapté à la fabrication de circuits intégrés hautes performances fonctionnant à haute fréquence. La technologie GaN permet notamment d'améliorer le niveau de puissance, le rendement et la compacité des transistors HEMTs (Transistors à Haute Mobilité d'Electrons), donnant accès à des fonctionnalités nouvelles pour des applications en télécommunication terrestres et spatiales dans le domaine militaire (radars à antenne active pour la détection de cibles) et dans le domaine civil (télécommunications 5G). Cependant, une marge d'amélioration des performances et de la stabilité de ces composants reste possible et nécessaire pour aller vers des dimensions de transistors avec des longueurs de grille encore plus courtes. Ces travaux de thèse ont pour objectif d'investiguer par une approche multi-techniques combinant XPS / nano-AES / STEM-EDS et mesures électriques l'origine de la limitation des performances électriques de HEMTs et de leur dégradation dans le temps. Une procédure de traitement des données XPS est proposée pour permettre de réaliser une quantification précise des matériaux à base de GaN qui nécessite de séparer la contribution N 1s du massif Ga LMM et de prendre en compte la formation de gallium métallique lors du profilage par abrasion ionique. Des analyses Auger en sonde localisée (nano-AES) sont réalisées directement sur les transistors préparés par FIB en lames minces permettant d'apporter des informations complémentaires aux mesures chimiques et structurales obtenues par STEM-EDX. Cette approche originale a été employée avec succès pour guider la fabrication du HEMT vers une structure optimisée, étudier et comprendre la dérive de comportement électrique sous stress en le reliant à une origine chimique et/ou structurale
Adhesion at the glass/metal interface probed by Brillouin oscillations in colored picosecond acoustics
No full textInternational audienceGlass is a common material already employed in everyday applications, which has gained considerable interest for electronic components, due to its attractive electrical, physical, and chemical properties, as well as its prospects for a cost-efficient solution. Adhesion of thin metal film on glass is especially critical and bonding between glass and metal can broaden the applications of glass in many industrial areas. Numerous methods have been developed to assess the adhesion of thin films to substrates. Among these, acoustic waves and particularly ultra-high frequency acoustic waves, are highly sensitive to adhesion defects. At a poor interface, acoustic waves are much more reflected than expected and therefore much less transmitted. In this work, we use picosecond acoustics to measure both the thickness of metal film and the acoustic transmission coefficient at the interface with a glass substrate. Picosecond acoustics is an ultrafast laser technique that implements a nanoscale pulseecho technique. By making measurements at various wavelengths, we detect subtle changes in the photoacoustic response, which can be used to improve measurement accuracy. The methodology demonstrated here can be readily extended to any system comprising a metal film on a transparent substrate. This versatility allows for potential applications in various fields, including flexible electronics and space mirrors.☆ This article is part of a Special issue entitled: 'ICMCTF 2025 (SCT)' published in Surface & Coatings Technology.</p