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Pseudopaline-mediated zinc uptake by Pseudomonas aeruginosa drives clinically relevant phenotypes and infection outcomes
No full textInternational audienceBiological metals are vital trace elements required by metalloproteins, which are involved in virtually every cellular, structural, and catalytic function of the bacterial cell. Bacterial pathogenesis involves a tug-of-war between the host's nutritional immunity sequestering essential metals and the invading pathogens that deploy adapted high-metal affinity uptake strategies, such as metallophores, in order to efficiently circumvent these defense mechanisms. Pseudopaline is a metallophore produced and secreted by Pseudomonas aeruginosa to acquire zinc when the bioavail ability of this metal is severely restricted, as in the presence of a strong metal che lator such as EDTA, or during infections when the nutritional immunity of the host is active. We show that when facing strong metal chelation, the general Znu zinc uptake pathway becomes ineffective and only the pseudopaline pathway is capable of supplying the bacteria with the necessary zinc to maintain their growth, establishing that the pseudopaline pathway is the last-resort pathway for the bacteria to acquire zinc under such restricted growth conditions. Based on this statement, the present study explores the pleiotropic role of pseudopaline-mediated zinc acquisition on clinically relevant phenotypes such as biofilm formation and associated antibiotic tolerance, as well as its capacity to determine infection outcomes using cell-culture and murine models. The expression of pseudopaline-dependent phenotypes in such a diversity of biological contexts demonstrates the essentiality of this specific metal uptake system for P. aeruginosa pathogenicity during infection. We therefore identify this machinery as a promising therapeutic target for P. aeruginosa infections
Postdoc report (PO3.1): Symptomatic response to network attacks
No full textThis report summarizes the research efforts of the postdoctoral project PO3.1, which was part of Lot 3 within the Superviz project (ANR-22-PECY-0008) supported by the French National Research Agency under the France 2030 label. The primary objective of PO3.1 was to design and implement a prototype of an AI-based intrusion response system capable of reacting to ongoing network attacks in real time. The motivation for pursuing this line of research lies in the growing difficulty of providing timely and effective responses to such attacks within modern, complex network environments
New insight on the properties of the superconducting iron spin ladder BaFe<sub>2</sub>S<sub>3</sub>
No full textInternational audienceBaFe2S3 and BaFe2Se3 are the only two quasi-one-dimensional iron-based compounds that become superconductors under pressure. Interestingly, these two compounds exhibit different symmetries and properties. While more detailed and recent studies on BaFe2S3 using single crystals have advanced the field towards a more universal description of this family, such a study is still lacking for the compound BaFe2S3 . Here, we present a detailed study of the crystalline and magnetic structures performed on single crystals using X-ray and neutron diffraction. We demonstrate a polar structure at room temperature within the Cm2m followed by a structural transition at TS = 130 K to the polar Pb21m space group, space group. This space group remains unchanged across the magnetic transition at TN = 95 K, revealing multiferroic characteristics with a weak magnetoelastic coupling. The determined magnetic structure is monoclinic (Pam ), with non-collinear Fe magnetic moments, tilted from the rung axis. This reexamination of the temperature-dependent properties of BaFe2S3 provides new insights into the physics of this system from multiple key perspectives
Proton Pandemonium: A first look at the Cl()P decay scheme
No full textInternational audiencePositron decays of proton-rich nuclides exhibit large values, producing complex cascades which often involve various radiations, including protons and rays. Often, only one of the two are measured in a single experiment, limiting the accuracy and completeness of the decay scheme. An example is Cl, for which protons and rays have been measured in detail individually but never with substantial sensitivity to proton- coincidences. The purpose of this work is to provide detailed measurements of Cl -delayed proton decay including -- sequences, extract spectroscopic information on S excited states as well as their feeding, and compare to shell-model calculations. A fast, fragmented beam of Cl provided was deposited in the Gaseous Detector with Germanium Tagging (GADGET) system. GADGET's gas-filled Proton Detector was used to detect -delayed protons, and the Segmented Germanium Array (SeGA) was used to detect -delayed rays. Up to 18 previously unobserved -delayed proton transitions have been discovered, most of which populate excited states of P. Here present the first detailed Cl()P decay scheme and find improved agreement with theoretical calculations of the Gamow-Teller strength distribution for S excitation energies MeV. The present work demonstrates that the capability to detect -delayed protons and rays in coincidence is essential to construct accurate positron decay schemes for comparison to theoretical nuclear structure calculations. In some respects, this phenomenon for -delayed protons resembles the pandemonium effect originally introduced for -delayed rays
Slowly rotating Black Holes in DHOST Theories
No full textInternational audienceWe study slowly rotating black hole solutions within Degenerate Higher Order Scalar Tensor (DHOST) theories. Starting from a static, spherically symmetric metric solution of a DHOST theory, we employ the Hartle-Thorne ansatz to model a slowly rotating spacetime. We show that the differential equation governing the frame-dragging function (which is supposed to depend on the radial coordinate only) is integrable for any DHOST theory allowing us to obtain its explicit form. We also consider angular dependence in and show that regularity at the horizon and at infinity forbids it, as in General Relativity. As an illustration of the formalism introduced here, we study the slowly-rotating version of black hole solutions with primary hair obtained recently, examining the influence of the rotation on the Innermost Stable Circular Orbit (ISCO) and on the circular light trajectories in the equatorial plane
A Mnemonic Matrix Rule for (Split) Octonionic Multiplication and its Extension to the Cayley--Dickson Tower
No full textInternational audienceWe present a compact mnemonic device for computing the product of two (split) octonions written in Cayley--Dickson form q+l p with q,p in H. The rule appears as a simple (R+L) pattern of right-ordered and left-ordered (quaternionic) products inside a 2X2 quaternionic matrix model. The pattern extends verbatim to all algebras in the Cayley--Dickson tower, providing an efficient computational tool in non-associative settings. To our knowledge, this explicit ``(R+L)'' mnemonic does not appear in the classical literature on octonions or composition algebras
The Domain Adaptation problem in photometric redshift estimation: a solution applied to the HSC Survey
No full textInternational audienceThe multi-band HSC-CLAUDS survey comprises several sky regions with varying observing conditions, only one of which, the COSMOS Ultra Deep Field (UDF), offers extensive redshift coverage. We aim to exploit a complete sample of labeled galaxies from the COSMOS UDF at i<25 (z<~5) to train a convolutional neural network (CNN) and infer more accurate photometric redshifts in the other regions than those currently available from SED-fitting methods. To address the severe domain mismatch problem we observed when applying the trained CNN to regions other than the COSMOS UDF, we developed an unsupervised adversarial domain adaptation network that we grafted onto the CNN. The method is validated by three tests: the predicted redshifts are compared to the spectroscopic redshifts that are available for limited samples of mostly bright galaxies; the predicted redshift distributions of the entire galaxy population of a given field in several intervals of magnitude are compared to those of the COSMOS UDF, assumed to be representative; the redshifts predicted for a sample of galaxies selected by narrow-band filter observations sensitive to [OII] emitters at z~1.47 are compared to those of confirmed [OII] emission line galaxies. The results show successful domain adaptation: the network is able to transfer its redshift classification capability learnt from the COSMOS UDF to other regions of HSC-CLAUDS. Accuracy varies depending on magnitude and redshift, following that of the labels we used, but far exceeds that of currently available photometric redshifts. The catalogs of CNN redshifts we inferred for the XMM, DEEP2 and ELAIS fields and for the remaining COSMOS region (~4 million sources in total at i<25) are made public
Thermal coupling between a Small Modular Nuclear Reactor and a High-Temperature Steam Electrolysis process: Energy performance mapping of key design options
No full textInternational audienceThis article presents the main results of a three-year R&D program on the coupling of a Small Modular Reactor(SMR) nuclear unit to a hydrogen production process using High-Temperature Steam Electrolysis (HTSE).Different coupling architectures are investigated and their energetic evaluation is performed in comparison witha reference configuration. The separate effects that are considered are comprehensive and include: thermalcoupling (with or without, unidirectional or bidirectional − modulo internal heat recovery effort in the HTSEprocess itself), direct or indirect steam supply, location of the Rankine cycle extraction point, pressurization ofthe HTSE (with or without mechanical energy recovery through gas expansion) and oxygen content (impact ofthe swept gas). Remarkably, the simulation results obtained on the reference configuration show a gain of over13% in hydrogen production compared with the solution involving no thermal coupling between the SMR andthe HTSE process (when HTSE heat is provided through electrical heaters), with a deviation as low as 3 % froman idealized configuration with freely available heat. It even outperforms the heat-pump solution by more than 4%. These key energetic results were supplemented by other technical criteria, such as those relating to safety andtechnological maturity
Présentation de madbot au BioStream
No full textInternational audiencemadbot (Metadata And Data Brokering Online Tool) is a web application that provides a dashboard for managing research data and metadata. Madbot aims to support biologists in handling and publishing their data and metadata while adhering to best practices in the field. This includes raising awareness of and ensuring compliance with the FAIR principles (Findable, Accessible, Interoperable, and Reusable).madbot (Metadata And Data Brokering Online Tool) est une application web qui fournit un tableau de bord pour la gestion des données et des métadonnées de recherche. Madbot a comme objectif d’accompagner les biologistes dans la gestion et la publication de leurs données et métadonnées, en conformité avec les bonnes pratiques en la matière. Cela inclut une sensibilisation et un respect des principes FAIR (Facile à trouver, Accessible, Interopérable et Réutilisable)
Nuclear collectivity and the harmonic spectrum of two-body correlations
No full textInternational audienceHigh-energy nuclear collisions have opened a new experimental method to reveal collective behavior in nuclear ground states through the lens of many-body correlations of nucleons. Using ab initio lattice and variational calculations of Ne and O, we study how emergent phenomena such as deformation or clustering can be identified in these systems from the dependence of their two-body density distributions on the relative azimuthal angle of nucleon pairs. A harmonic analysis of the correlation functions reveals in particular a dominant quadrupole component in Ne, consistent with a bowling-pin picture, and a prominent triangular modulation in O, possibly indicative of alpha-cluster correlations. Given that such structures can be accurately identified in high-energy collider experiments, these findings open a new paradigm for analyzing emergent collective behavior in atomic nuclei, relating their intrinsic shapes to the harmonic spectrum of microscopic correlations