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Quantifying bacterial Chemotaxis in controlled and stationary chemical gradients with a microfluidic device
No full textInternational audienceChemotaxis refers to the ability of organisms to detect chemical gradients and bias their motion accordingly. Quantifying this bias is critical for many applications and requires a device that can generate and maintain a constant concentration field over a long period allowing for the observation of bacterial responses. In 2010, a method was introduced that combines microfluidics and hydrogel to facilitate the diffusion of chemical species and to set a linear gradient in a bacterial suspension in the absence of liquid flow. The device consists of three closely parallel channels, with the two outermost channels containing chemical species at varying concentrations, forming a uniform, stationary, and controlled gradient between them. Bacteria positioned in the central channel respond to this gradient by accumulating toward the high chemoattractant concentrations. Video-imaging of bacteria in fluorescent microscopy followed by trajectory analysis provide access to the key diffusive and chemotactic parameters of motility for the studied bacterial species. This technique offers a significant advantage over other microfluidic techniques as it enables observations in a stationary gradient. Here, we outline a modified and improved protocol that allows for the renewal of the bacterial population, modification of the chemical environment, and the performance of new measurements using the same chip. To demonstrate its efficacy, the protocol was used to measure the response of a strain of Escherichia coli to gradients of -methylaspartate across the entire response range of the bacteria and for different gradients
Checkpointing Optimisation to Prepare Future Exascale Plasma Turbulence Simulations
No full textInternational audienceThe advent of exascale computing has revolutionized high-performance computing (HPC) and enabled unprecedented advancements in nuclear fusion research. Simulations of plasma turbulence dynamics, such as the GYSELA code, now achieve unparalleled precision and complexity. However, this progress is accompanied by significant challenges in managing the exponential growth of data generated by these simulations. Traditional input/output (I/O) methods struggle to handle the massive data volumes, heightened concurrency, and fault-tolerance requirements inherent to exascale systems.This paper investigates the I/O bottlenecks inherent in exascale computing, with a particular focus on the checkpointing mechanisms of GYSELA. These mechanisms are critical for ensuring fault tolerance and must handle several terabytes of data efficiently to avoid undermining computational performance. We analyze the current implementation of GYSELA's checkpointing mechanism managed via the PDI data interface, identifying its limitations and proposing two alternative approaches aimed at enhancing scalability and resilience. Experiments conducted on pre-exascale architectures validate the efficiency of these methods through both strong and weak scaling benchmarks. We reduced the checkpointing execution time by a factor of four, achieving near-optimal bandwidth utilisation, and we have identified implementations well-suited for exascale architectures. Our findings suggest the potential for notable performance improvements and offer insights that could help optimise I/O operations in exascale simulations
Three-pion Bose-Einstein correlations measured in proton-proton collisions
No full textInternational audienceA study on the Bose-Einstein correlations for triplets of same-sign pions is presented. The analysis is performed using proton-proton collisions at a centre-of-mass energy of = 7 TeV, recorded by the LHCb experiment, corresponding to an integrated luminosity of 1.0 fb. For the first time, the results are interpreted in the core-halo model. The parameters of the model are determined in regions of charged-particle multiplicity. This measurement provides insight into the nature of hadronisation in terms of coherence, showing a coherent emission of pions
SCCS – Opinion on Prostaglandin Analogues: Methylamido-Dihydro-Noralfaprostal (MDN), Isopropyl Cloprostenate (IPCP), Dechloro Dihydroxy Difluoro Ethylcloprostenolamide (DDDE) - SCCS/1680/25 - Preliminary Opinion
No full textInternational audienceSCCS – Opinion on Prostaglandin Analogues: Methylamido-Dihydro-Noralfaprostal (MDN), Isopropyl Cloprostenate (IPCP), Dechloro Dihydroxy Difluoro Ethylcloprostenolamide (DDDE) - SCCS/1680/25 - Preliminary OpinionPreliminary Opinion open for comments - Deadline for comments: 18 August 2025Adopted on: 28 May 2025 (227 pages)Mis en ligne : 6 June 2025U. Bernauer, L. Bodin, Q. Chaudhry, P.J. Coenraads, J. Ezendam, E. Gaffet, C. L. Galli, E. Panteri, V. Rogiers, Ch. Rousselle, M. Stepnik, T. Vanhaecke, S. Wijnhoven, E. Benfentati, N. Cabaton, E. Corsini, Ch. Delmaar, A. Koutsodimou, H. Louro, W. Uter, N. von Goetzhttps://health.ec.europa.eu/publications/sccs-prostaglandin-analogues-methylamido-dihydro-noralfaprostal-mdn-isopropyl-cloprostenate-ipcp_enhttps://health.ec.europa.eu/document/download/55295a0e-1aa8-4380-a8db-84ecf85b711c_en?filename=sccs_o_302.pdfDetailsPublication date : 6 June 2025Author : Scientific Committee on Consumer Safety (SCCS)DescriptionSCCS members: U. Bernauer, L. Bodin, Q. Chaudhry, P.J. Coenraads (Chairperson), J. Ezendam (Rapporteur), E. Gaffet, C. L. Galli, E. Panteri, V. Rogiers (Rapporteur), Ch. Rousselle, M. Stepnik (Rapporteur), T. Vanhaecke, S. WijnhovenSCCS external experts: E. Benfenati, N. Cabaton, E. Corsini, Ch. Delmaar, A. Koutsodimou, H. Louro, W. Uter, N. von Goetz, Contact: [email protected] request from: European CommissionSCCS Number: SCCS/1680/25Adopted on: 28 May 2025Conclusion of the opinion:(1) In light of the data provided and taking under consideration the concerns raised by the SCCS in Opinion SCCS/1635/21,a) does the SCCS consider Ethyl Tafluprostamide safe when used in eyelash and eyebrow products up to a maximum concentration of 0.018 %?b) does the SCCS consider Methylamido-Dihydro-Noralfaprostal safe when used in eyelash and eyebrow products up to a maximum concentration of 0.03 %?c) does the SCCS consider Isopropyl Cloprostenate safe when used in eyelash and eyebrow products up to a maximum concentration of 0.005 %?Having evaluated all the evidence provided by the Applicants to support the safe use of the three prostaglandin analogues (PGAs) - Isopropyl Cloprostenate, Norbimatoprost and Dechloro Dihydroxy Difluoro Ethylcloprostenolamide - the SCCS is of the opinion that none of them can be considered safe for use in cosmetic products intended for promoting the growth of eyelashes and eyebrows.The SCCS’ conclusion is based on the potent pharmacological activity of the PGAs, even at low concentrations, and the lack of acceptable data that would make it possible to exclude any potential adverse effects resulting from reproductive/developmental toxicity. The latter is crucially important for PGAs in view that users of the PGA-containing cosmetic products will most likely be young women.More details on the SCCS concerns regarding safety of the PGAs are given in the section 8.(2) Alternatively, what is according to the SCCS the maximum concentration considered safe for use of Ethyl Tafluprostamide, Methylamido-Dihydro-Noralfaprostal and Isopropyl Cloprostenate, respectively, in eyelash and eyebrow products?/(3) Does the SCCS have any further scientific concerns regarding the use of Ethyl Tafluprostamide, Methylamido-Dihydro-Noralfaprostal and Isopropyl Cloprostenate in cosmetic products?/Keywords:SCCS, scientific opinion, prostaglandin analogues, PGAs, Ethyl Tafluprostamide, Methylamido-Dihydro-Noralfaprostal, Isopropyl Cloprostenate, Regulation 1223/2009Opinion to be cited as:SCCS (Scientific Committee on Consumer Safety), Opinion on prostaglandin analogues used in cosmetic products, preliminary version of 28 May 2025, SCCS/1680/25
Circuits électroniques à températures cryogéniques pour la lecture massive de qubits de spin
No full textSemiconductor spin qubits are a promising platform for large-scale quantum computing as they benefit from a small footprint and fabrication processes compatible with the established semiconductor industry. While spin qubits are operated at cryogenic temperatures, the electronic circuits ensuring their operation are usually kept at room temperature. Therefore, more than thousands of signals must be conveyed through the cryostat.Moving the control electronics inside the cryostat would improve the system scalability, reducing the connections between room temperature and cryogenic stages to fewer low-frequency cables. This thesis aims to develop cryogenic integrated circuits designed to perform the impedancemetry readout of spin qubits and adapted to large scale readout. Impedancemetry is a readout method similar to the established method of reflectometry, but in which the impedance of the resonator connected to the qubit is measured directly, avoiding the need for complex impedance matching of the resonator. On the other hand, the readout circuits and resonators must be placed in close proximity.First, we present a theoretical study comparing the performances of impedancemetry and reflectometry readout. Impedancemetry demonstrates an improved phase sensitivity since it is limited only by the internal quality factor of the resonator. However, placing the resonator at a higher temperature stage increases its thermal noise, limiting the Signal-to-Noise Ratio (SNR).We perform simulations showing that impedancemetry is compatible with frequency multiplexing, allowing to read several qubits with a single readout chain. Then, we design a circuit in the industrial Fully-Depleted Silicon-On-Insulator (FDSOI) 28nm technology to demonstrate the readout concept. The tests are performed at 4.2K, although the circuit is compatible with an operation at 500mK. During the circuit characterization, an additional discrete SiGe LNA is used. It was also designed during this Ph.D. to be used as the second amplification stage of an impedancemetry or reflectometry readout. At 4.2K, the integrated circuit consumes 590µW for a bandwidth of 500MHz. A digital capacitance is used to emulate the behavior of a qubit and evaluate the sensitivity of the readout chain. The sensitivity is of 35 aF.µV/√Hz at 4.2K, limited by the resonator thermal noise, with an improvement by a factor 3 predicted at 500mK.Les qubits de spin sur semi-conducteurs constituent une plateforme prometteuse pour le calcul quantique à grande échelle, car ils bénéficient d’une taille réduite et de procédés de fabrication compatibles avec l’industrie des semi-conducteurs. Bien que les qubits de spin fonctionnent à des températures cryogéniques, les circuits électroniques assurant leur contrôle sont généralement placés à température ambiante. Plusieurs milliers de câbles doivent donc traverser le cryostat.Placer l’électronique de contrôle à l’intérieur du cryostat permettrait de limiter les connexions reliant l’étage à température ambiante avec les étages cryogéniques à un petit nombre de câbles portant des signaux basses fréquences. Cette thèse vise à développer des circuits intégrés à températures cryogéniques conçus pour réaliser la lecture par impédancemétrie de qubits de spin et adaptés à une lecture à grande échelle. L’impédancemétrie est une méthode de lecture similaire à la méthode éprouvée de la réflectométrie, mais dans laquelle l’impédance du résonateur connecté au qubit est mesurée directement, ce qui permet d’éviter une optimisation complexe de l’adaptation d’impédance du résonateur. En contrepartie, les circuits de lecture doivent être placés à proximité immédiate des résonateurs.Tout d’abord, nous présentons une étude théorique comparant les performances des lectures par impédancemétrie et par réflectométrie. L'impédancemétrie présente une sensibilité en phase améliorée, étant limitée uniquement par le facteur de qualité interne du résonateur. Cependant, placer le résonateur à une température plus élevée augmente son bruit thermique, limitant le rapport signal sur bruit (SNR). Nous réalisons des simulations montrant que l'impédancemétrie est compatible avec le multiplexage fréquentiel, permettant la lecture de plusieurs qubits par la même chaîne de lecture. Nous concevons ensuite un circuit sur la technologie Fully-Depleted Silicon-On-Insulator (FDSOI) 28nm pour démontrer le principe de lecture. Les tests sont effectués à 4.2K, bien que le circuit soit compatible avec une utilisation à 500mK. Pendant la caractérisation du circuit, un deuxième LNA discret en SiGe est utilisé. Ce LNA a également été conçu au cours de cette thèse pour être utilisé comme second étage d’amplification d’une lecture par impédancemétrie ou réflectométrie. À 4.2K, le circuit intégré consomme 590µW pour une bande passante de 500MHz. Une capacité numérique est utilisée pour émuler le comportement d’un qubit et évaluer la sensibilité de la chaîne de lecture. La sensibilité est de 35 aF.µV/√Hz à 4.2K, limitée par le bruit thermique du résonateur, avec une amélioration d’un facteur 3 prévue à 500mK
Microwells as Minimalistic Niches to Study Heterotypic Interactions of Stromal and Hematopoietic Stem Cells
No full textInternational audienceHematopoietic stem and progenitor cells (HSPCs) can migrate and reside within the bone marrow in distinct microenvironments or niches. The niches organize around specific stromal cells, such as endothelial cells at the capillary or sinusoid walls, and osteoblasts along the bone matrix. Within each niche, a specific combination of external cues, including secreted and diffusible factors, cell-matrix, and cell-cell interactions, controls HSPCs behavior and fate. Deciphering the interplay between HSPCs and stromal cells of the niches is challenging: in vivo, it is hindered by the opacity of the bone matrix; in vitro, classical co-culture models only poorly recapitulate essential features of the physiological niches. The difficulty is moreover amplified by the exceptional migration capacity of HSPCs.In this chapter, we present a method to overcome these limitations by producing arrays of microwells designed to mimic bone marrow niches in a functional manner. These "microniches" promote a long-term interaction between the HSPC and a stromal cell of interest. We describe their microfabrication based on a maskless photolithography method allowing the production of arrays of microwells with reproducible volume and geometry, and the iterative improvement of the geometric design of the wells. We describe the loading and culture of stromal cells with HSPCs. We discuss the potentiality of microwells, in basic and applied research, as a platform to investigate molecular mechanisms involved in direct cell-cell interactions and local effects of diffusible factors, for any adherent and non-adherent cells of interest
A comparative study on ray-tracing and physical-optics methods for the analysis of transmitarray antennas
No full textInternational audienceThis study compares the accuracy of two semi-analytical methods based on ray tracing (RT) and physical optics (PO) for the analysis and design of transmitarrays of different sizes. The assessment considers multiple focal-to-diameter ratios and eight unit cells implementing 3-bit uniform phase quantization at 30 GHz. The results, validated by full-wave simulations, demonstrate that both the RT and PO methods yield excellent agreement in standard-profile configurations. However, the RT approach, which assumes the transmitarray to be in the far-field region of the primary feed, provides a wrong evaluation of the gain of low-profile antennas, with errors up to 1.5 dB at 34 GHz. In contrast, the PO method accounts for near-field effects and accurately predicts the transmitarray performance even when the focal distance is comparable to the wavelength. Additionally, the PO method enables the analysis of large antennas with computational efficiency comparable to RT, requiring approximately four minutes for transmitarrays with diameters of 30 wavelengths
Euclid: Early Release Observations -- The surface brightness and colour profiles of the far outskirts of galaxies in the Perseus cluster
No full textInternational audienceThe Perseus field captured by Euclid as part of its Early Release Observations provides a unique opportunity to study cluster environment ranging from outskirts to dense regions. Leveraging unprecedented optical and near-infrared depths, we investigate the stellar structure of massive disc galaxies in this field. This study focuses on outer disc profiles, including simple exponential (Type I), down- (Type II) and up-bending break (Type III) profiles, and their associated colour gradients, to trace late assembly processes across various environments. Type II profiles, though relatively rare in high dense environments, appear stabilised by internal mechanisms like bars and resonances, even within dense cluster cores. Simulations suggest that in dense environments, Type II profiles tend to evolve into Type I profiles over time. Type III profiles often exhibit small colour gradients beyond the break, hinting at older stellar populations, potentially due to radial migration or accretion events. We analyse correlations between galaxy mass, morphology, and profile types. Mass distributions show weak trends of decreasing mass from the centre to the outskirts of the Perseus cluster. Type III profiles become more prevalent, while Type I profiles decrease in lower-mass galaxies with cluster centric distance. Type I profiles dominate in spiral galaxies, while Type III profiles are more common in S0 galaxies. Type II profiles are consistently observed across all morphological types. While the limited sample size restricts statistical power, our findings shed light on the mechanisms shaping galaxy profiles in cluster environments. Future work should extend observations to the cluster outskirts to enhance statistical significance. Additionally, 3D velocity maps are needed to achieve a non-projected view of galaxy positions, offering deeper insights into spatial distribution and dynamics
Assessing bioinformatics software annotations: bio.tools case-study
No full textNational audienceReproducibility and reuse of digital bioinformatics resources are essential for the developmentof open and cumulative science, in line with FAIR principles. To search and reuse bioinformatics tools, scientists need to be confident enough with the reliability of their annotations. Our study focuses on the quantitative and qualitative evaluation of semantic annotations in the bio.tools registry, which serves more than 30,000 bioinformatics tool descriptions, annotated with the EDAM ontology. In this work we propose to study how the EDAM ontology is used to categorize software based on scientific disciplines and the kind of data processing they allow. We also evaluate how qualitative are the annotations based on Shannon entropy. We emphasize that a particular attention should be given to the whole set of inherited annotations, from the used ontology. Our results underline the need for automatic tools to support annotation curation, reducing the annotation cost for domain experts. This study is a preliminary work aimed designing novel annotation approaches based on the combination of knowledge graphs and large language models towards more findable and reusable bioinformatics tools.</p
Measurement of event shapes in minimum-bias events from proton-proton collisions at = 13 TeV
No full textInternational audienceA measurement of event-shape variables is presented, using a data sample produced in a special run with approximately one inelastic proton-proton collision per bunch crossing. The data were collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 64 b. A number of observables related to the overall distribution of charged particles in the collisions are corrected for detector effects and compared with simulations. Inclusive event-shape distributions, as well as differential distributions of event shapes as functions of charged-particle multiplicity, are studied. None of the models investigated is able to satisfactorily describe the data. Moreover, there are significant features common amongst all generator setups studied, particularly showing data being more isotropic than any of the simulations. Multidimensional unfolded distributions are provided, along with their correlations