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Resolving structural variations missed by short-read sequencing uncovers their pathogenicity
No full textInternational audienceBackground: Short-read genome sequencing (sr-GS) affords efficient and accurate characterisation of apparently balanced chromosomal rearrangement (ABCR) breakpoints except in 9%-11% of cases that remain undetectable.Methods: Among 117 ABCR that we studied in patients with abnormal phenotype, 14 (11.9%) could not be detected by our current strategy including sr-GS, alignment against the GRCh38 reference genome and structural variant (SV) detection using Breakdancer V.1.4.5. These were all reciprocal translocations, 10 of which implicated constitutive heterochromatin, acrocentric short arms or pericentromeric regions. We re-aligned the sequencing data against the T2T-CHM13 V.2.0 reference genome and re-analysed them using five other SV callers (DELLY, GRIDSS, LUMPY, Manta and SvABA). In addition, 11 ABCRs were further characterised using FISH, linked-read sequencing, long-read sequencing or optical genome mapping, either isolated or combined.Results: We were able to characterise the breakpoints at the bp level for 12 translocations and identify specific breakpoint patterns using Integrative Genome Viewer (IGV). In each translocation, at least one breakpoint involved highly repetitive elements such as alpha-satellites, segmental duplications, satellite repeats or other poorly mapped regions. For six out of 12 patients, one of the breakpoints could explain the phenotype either by gene disruption (CAMTA1, DYRK1A, NLGN4X) or position effect (BMP2, DIAPH2, SIX3).Conclusion: Failure of sr-GS is due to highly repetitive genomic regions at SV breakpoints, either absent from the reference genome or not attributed to a unique position. The resolution of ABCRs is essential to patients' care since it allowed us to conclude to a pathogenic variant in 50% of patients
Subcycling Strategy for Finite‐Volume Updated‐Lagrangian Methods Applied to Fluid–Structure Interaction
No full textInternational audienceIn this article, we propose and investigate an explicit partitioned method for solving shock dynamics in fluid–structure interaction (FSI) problems. The method is fully conservative, ensuring the local conservation of mass, momentum, and energy, which is crucial for accurately capturing strong shock interactions. Using an updated‐Lagrangian finite‐volume approach, the method integrates a subcycling strategy to decouple time steps between the fluid and structure, significantly enhancing computational efficiency. Numerical experiments confirm the accuracy and stability of the method, demonstrating that it retains the key properties of monolithic solvers while reducing computational costs. Extensive validation across 1D and 3D FSI problems shows the method's capability for large‐scale, fast transient simulations, making it a promising solution for high‐performance applications
High frequency piezoelectric DC/DC converter
No full textInternational audienceToday, one of the challenges in power electronics is the increase of the power-density, mainly done by the increase of the switching frequency. With new semiconductor technologies like GaN HEMT devices, we can push further the switching frequency allowing more power-density. Nevertheless, limits are reached with passive materials such as inductors. In this context, piezoelectric resonators (PR) are used to offer an interesting alternative compare to inductor beyond MHz switching frequency. However, using PR impacts both topologies and control. This paper shows how such a component can be used in power electronics, as well as the main challenges that must be overcome to make it truly competitive compared to the inductor
Rheology of bituminized waste products
No full textInternational audienceThe French nuclear industry has produced a large diversity of waste, some of which is embed inside bitumen that is used as a confinement matrix. Understanding the rheology of bituminous waste products (BWP) is important as it influences their behavior under thermal stress, under ionizing radiation or under leaching conditions. BWPs are non brownian dispersions of various inorganic salts presenting a spread granulometry inside a 70/100 pure bitumen matrix. Proportions are 60% in weight of bitumen and of 40% in salts, representing a volume rate between 20% and 30%. Rheology of pure bitumen and synthetized model BWPs, containing various volume fraction of salts, was characterized as a function of the temperature. Several sequences were considered such as creep, flow curve and shear rate step. Pure bitumen behaves as a viscoelastic matrix highly thermodependant, with a short time constant (under a second), thus behaving mostly as a newtonian fluid in most of the shear rate ranges considered. In the range of 20-200°C, its viscosity loses 7 decades. Including salts increases the viscosity following Newton’s law, until a point where BWPs with the higher load of salts behave as a yield stress fluid. A Herschel Bulkley model was used to successfully fit experimental points, with parameters varying with volume fraction of salts and temperature as power laws. These results were then introduced inside a thermo-mechanical model to assess the influence of rheological properties on the convective flow of a BWP undergoing a thermal stress. We will first examine the mechanisms behind the appearance of yield stress effects related to adhesive forces. Then we will show how convective flows are reduced, partially or completely blocked depending on the strength of buoyancy relative to viscous or yield stresses
Hearing the Shape of a Cuboid Room Using Sparse Measure Recovery
No full textInternational audienceThis article explores a variant of Kac's famous problem, ‘‘Can one hear the shape of a drum?'', by addressing a geometric inverse problem in acoustics. Our objective is to reconstruct the shape of a cuboid room using acoustic signals measured by microphones placed within the room. By examining this straightforward configuration, we aim to understand the relationship between the acoustic signals propagating in a room and its geometry. This geometric problem can be reduced to locating a finite set of acoustic point sources, known as image sources. We model this issue as a finite-dimensional optimization problem and propose a solution algorithm inspired by super-resolution techniques. This involves a convex relaxation of the finite-dimensional problem to an infinite-dimensional subspace of Radon measures. We provide analytical insights into this problem and demonstrate the efficiency of the algorithm through multiple numerical examples
Tailoring structural and optical properties of Ta2O5 thin films via radio frequency magnetron sputtering for high-refractive index transparent materials
No full textInternational audienceThis work investigates the impact of growth conditions, oxygen flow, sputtering power density, and annealing temperature on the optical performance of Ta2O5 thin films grown on Silicon (Si) substrate by RF sputtering. The objective is to determine whether the amorphous or crystalline phase provides the optimal trade-off between high refractive index (n), low optical loss (k), and broad optical transparency window (Esize).A near-stoichiometric Ta/O ratio of 0.38, close to the ideal 0.40 was achieved at a power density of 3.29 W/cm² and oxygen flow of 8 sccm. Crystallization begins at TA=650 °C, resulting in a predominant orthorhombic and a minor hexagonal phase as demonstrated by XRD and confirmed by TEM. This crystallization was accompanied by a densification of 7.85 g.cm-3 at 750 °C, but showed signs of structural degradation at 850 °C.Ellipsometry shows an increase in n during crystallization to 2.24 at 750 °C, before decreases at 850 °C. The onset of k redshifts from 4 to 3 eV, and the optical band gap (Eg) dropped from 4.14 eV to 2.5 eV following crystallization. Transmittance (T), calculated using the transfer matrix method (TMM), showed an average of 80% over 1-4 eV range for amorphous films and narrowed below 3 eV in crystalline films due to defect-induced mid-gap states.Our findings underscore a critical balance where crystallization enhances the refractive index of Ta2O5 thin films at the expense of a restricted transparency window in the NIR-visible range
CO11.2 - Explorer les fonctions cognitives dans UK Biobank avec une analyse de médiation causale
No full textInternational audienceL'inférence causale dans les études d'observation est principalement utilisée pour mesurer l'effet causal d'une exposition sur un résultat. Dans de nombreux domaines, il est tout aussi important de comprendre le mécanisme d'action, car cela permet d'identifier des cibles d'intervention intermédiaires potentielles et, plus généralement, d'approfondir la compréhension des processus qui conduisent au résultat observé. C'est l'objectif de l'analyse de médiation qui vise à séparer l'effet causal total en une composante indirecte, agissant par l'intermédiaire d'un effet sur un troisième groupe de variables d'intérêt appelées médiateurs, et une composante directe, via l'ensemble des autres mécanismes d'action. La validité de cette analyse repose sur des hypothèses d'identifiabilité fortes, pour lesquelles nous présentons des recommandations pratiques
Characterization and modeling of the performance and durability of praseodymium oxide infiltrated oxygen electrodes
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HYDROGEN SUPPLY CHAINS FOR DECARBONIZING DEPLOYABLE MILITARY CAMPS: INSIGHTS FROM THE INDY PROJECT
No full textInternational audienceThe energy transition is a global priority, with military forces seeking to reduce their dependence on fossil fuels. Deployable military camps are almost entirely reliant on fossil fuels, which not only increases their environmental footprint but also poses logistical vulnerabilities. These challenges are further compounded by the increasing energy demands of modern military equipment, thus leading to the research of complex compromises in terms of cost, environment and technology installations.The INDY project aims to address this issue by developing a strategic roadmap to implement energyindependent and efficient solutions for future deployable military camps. A key focus of the project is integrating renewable energy sources (RES) into military operations and leveraging hydrogen for diverse applications, including mobile and nomadic systems, electricity and heat generation, and local storage to manage peak loads. As achieving full energy independence and CO2 free installations for military camps may be challenging, the study explores the potential for long-distance hydrogen supply chains to replace diesel logistics. Three supply chain alternatives are evaluated: compressed hydrogen, liquid hydrogen, and liquid organic hydrogen carriers (LOHC) and compared to diesel supply. The methodology emphasizes a proof-of-concept approach rather than definitive conclusions, as real military consumption data was unavailable, requiring approximated consumption profiles.The study considers all phases of the hydrogen chain-production, storage, transportation, conditioning, and reconditioning-and evaluates its impact on the energy mix of a simplified military camp. Optimization problem is written using a MILP formulation and the PERSEE/CAIRN tool developed by CEA, to minimize costs (Net Present Value) under greenhouse gas (GHG) emission constraints. One case study is proposed taking into account the energy mix (cost and CO2 content) and the impact on the sizing phase. A distance between the production site and the camp is included using, as well as the different lifetime of hydrogen chain components. Key questions addressed include: 1. Can a hydrogen supply chain significantly reduce GHG emissions in military camps? 2. What hydrogen supply chain is best suited for military applications, and under what conditions?Results indicate that compressed and liquid hydrogen are viable external supply options to meet hydrogen demand, particularly when local RES is insufficient. Hydrogen can replace diesel for power generation when supplied efficiently. However, LOHC requires an adjacent heat source for the dehydrogenation process, emphasizing the importance of system design.</div
Toward an Algebraic Multigrid Method for the Indefinite Helmholtz Equation
No full textInternational audienceIt is well-known that multigrid methods are very competitive in solving a wide range of SPD problems. However, achieving such performance for non-SPD matrices remains an open problem. In particular, three main issues may arise when solving a Helmholtz problem: some eigenvalues may be negative or even complex, requiring the choice of an adapted smoother for capturing them, and because the near-kernel space is oscillatory, the geometric smoothness assumption cannot be used to build efficient interpolation rules. Moreover, the coarse correction is not equivalent to a projection method since the indefinite matrix does not define a norm. We present some investigations about designing a method that converges in a constant number of iterations with respect to the wavenumber. The method builds on an ideal reduction-based framework and related theory for SPD matrices to improve an initial least squares minimization coarse selection operator formed from a set of smoothed random vectors. A new coarse correction is proposed to minimize the residual in an appropriate norm for indefinite problems. We also present numerical results at the end of the paper