Science & Mathematics

Background: Using the Cap Analysis of Gene Expression technology, the FANTOM5 consortium provided one of the most comprehensive maps of Transcription Start Sites (TSSs) in several species. Strikingly, ∼ 72% of them could not be assigned to a specific gene and initiate at unconventional regions, outside promoters or enhancers. Results: Here, we probe these unassigned TSSs and show that, in all species studied, a significant fraction of CAGE peaks initiate at short tandem repeats (STRs) corresponding to homopolymers of thymidines (T). Additional analyses confirm that these CAGEs are truly associated with transcriptionally active chromatin marks. Furthermore, we train a sequence-based deep learning model able to predict CAGE signal at T STRs with high accuracy (∼ 81%). Extracting features learned by this model reveals that transcription at T STRs is mostly directed by STR length but also instructions lying in the downstream sequence. Excitingly, our model also predicts that genetic variants linked to human diseases affect this STR-associated transcription. Conclusions: Together, our results extend the repertoire of non-coding transcription associated with DNA tandem repeats and complexify STR polymorphism. We also provide a new metric that can be considered in future studies of STR-related complex traits.

This paper presents a comparison between piezoelectric filtering and passive LC filtering integrated into an HF class L−Piezo inverter. This L−Piezo inverter is a variant of class φ2 where the filtering of the second harmonic is carried out by a piezoelectric resonator. Piezoelectric filters are well known in the signal domain (RF filtering), but their use in the field of power electronics, as a temporary energy storage element, is rather recent. In power electronics, piezoelectricity has mainly been used as a transformer, in particular, to greatly increase voltages (backlight applications). A class L−Piezo inverter with Lithium Niobate (LNO) piezoelectric resonator is designed for a switching frequency of 10.4 MHz, an input voltage of 30 V, and an output power of 15 W. To compare these two filtering methods, two prototypes are built, one with piezoelectric filtering and one with passive LC filtering. Measurements show a reduction of 60% of the losses in the filter, while the volume of the filter is reduced by a factor of 50.

Communication présentée au colloque « Femmes, féminismes et recherches, trente ans après », Manifestation jeunes chercheurs, Université de Toulouse 2, 14-15 décembre 2012. Je voudrais présenter, dans le cadre de ce colloque, le panorama des recherches sur l'emploi domestique en Amérique Latine, et plus particulièrement en Colombie (mon terrain d'étude), des années 1970 à nos jours. Ce panorama me permettra de montrer comment ont été analysées les migrations dans les recherches sur l'emploi domestique ainsi que le passage d'une analyse marxiste à une réflexion en termes féministes puis de genre. Dans une première partie, je m'attacherai à comprendre « la naissance d'un champ de recherche », puis, dans une seconde partie, je traiterai des années 2000 et du renouveau des recherches sur l'emploi domestique, et enfin, dans un troisième temps, je montrerai comment coexistent et s'entrecroisent les réflexions sur les migrations internes et les migrations internationales en reprenant l'exemple des études sur la famille et l'emploi domestique.

Metasomatic iron and alkali-calcic (MIAC) mineral systems form district-scale metasomatic footprints in the upper crust that are genetically associated with iron oxideapatite (IOA), iron oxide and iron sulfide copper-gold (IOCG, ISCG), skarn, and affiliated critical and precious metal deposits. The development of MIAC systems is characterized by series of alteration facies that form key mappable entities in the field and along drill cores. Each facies can precipitate deposit types specific to the facies or host deposits formed at a subsequent facies. Defining the spatial and temporal relations between alteration facies and host rocks as well as with pre, syn, and post MIAC magmatic, tectonic, and mineralization events is essential to understanding the evolution of a MIAC system and to evaluating its overall mineral prospectivity. This paper proposes an ontology for MIAC systems that frames the key characteristics of the main alteration facies described and links it to a taxonomy and descriptive lexicons that allow the user to build an efficient data collection system tailored to the description of MIAC systems. The application developed by the Geological Survey of Canada for collecting field data is used as an example. The data collection system, including the application for collecting field data and the lexicons, are applicable to regional-and deposit-scale geological mapping as well as to drill core logging. They respond to the need for the metallogenic mapping of mineral systems and the development of more robust mineral prospectivity maps and exploration strategies for the discovery of critical and precious metal resources in MIAC systems

We study the problem of distributed statistical learning. More specifically, we consider the distributed training and inference setting. In the considered scenario, multiple nodes need to work together to predict some quantity of interest/event at a central node. Some nodes observe data related to the target quantity, while others do not; however, the nodes that do not have access to data form a link between the central node and the nodes that observe data. We consider the case in which a directed acyclic graph can model such a network. We study how one can train such a complex network in a distributed manner, i.e., without the exchange of raw data, for the case in which each node is equipped with a neural network to process the data. Inspired by the famous information bottleneck problem, we first use rate-distortion theory to derive an achievable trade-off between the network's performance under logarithmic loss and the rate of the messages passed between the nodes. Then, using the obtained trade-off, we showcase how one can derive a loss function that can jointly train the neural networks at the nodes in a distributed manner. We also study the problem of scheduling and power allocation for the proposed model for the star network topologies, i.e., in which the data observing nodes are connected directly to the central node making the prediction. Due to the distributed nature of the data and the lack of a known prior, no node can provide a definitive picture of the system and correctly decide the allocation of the resources. To overcome this issue, Prof. Abdellatif Zaidi patented a solution in which 1. Each device measures its own local assessment of how relevant is the data it holds for the inference task at hand and transmits it to the decision node. 2. That device also simultaneously sends the output activation values to the decision node. 3. The decision node combines all received information (activation values from the various devices as well as their individual local assessments) and then forms its own (global) assessment of how relevant each device's observation is. 4. The central nodes used the obtained assessments for scheduling for power allocation. In this thesis, we build upon the patent by presenting a method for computing the local and global assessments and proposing new scheduling and power allocation algorithms

Building mesostructured biomaterials is a challenging and exciting task that has attracted much attention because of their use as drug carriers or drug delivery systems. In the case of bioactive materials, the mesostructuration can also deeply impact their physico-chemical properties and the reactivity. In this study, we show how highly ordered mesoporosity influence the early steps of biomineralization process and the reactivity in binary (SiO2-CaO) and ternary (SiO2-CaO-P2O5) bioactive glasses. Conventional porous sol-gel glasses were synthesized using a classical route, while mesostructured glasses were elaborated using a non-ionic surfactant. Textural properties of these materials have been characterized. The in vitro biomineralization process was followed, using Particle Induced X-ray Emission (PIXE) associated to Rutherford Backscattering, Spectrometry (RBS), which are efficient methods for a highly sensitive multi-elemental analysis. Elemental maps of silicon, calcium and phosphorus were obtained at a micrometer scale and revealed for the first time a bulk reactivity for mesostructured glasses. This is a major advantage over conventional glasses, for which the first steps of biomineralization are limited to the periphery of the material. Their enhanced bioactivity combined with their possible use as drug-delivery systems make them promising candidates for bone regeneration.

Interventional C-arm systems are real-time X-ray imaging systems, that can perform tomographic acquisitions by rotating the C-arm around the patient ; however, C-arm cone-beam computed tomography (CBCT) achieves a lower contrast resolution than diagnostic CT, which is necessary in order to benefit from the clinical information of soft tissues in the brain. We propose a new C-arm CBCT acquisition and reconstruction framework to increase low-contrast detection in brain soft-tissue imaging. In order to emulate a bow-tie filter, a dualrotation acquisition is proposed. To account for all the specificities of the dual-rotation acquisition, a dedicated iterative reconstruction algorithm is designed, that includes the ramp filter in the cost function. By switching from filtered backprojection (FBP) to backprojection-filtration (BPF) reconstruction methods, we propose an alternative, direct reconstruction method for dual-rotation acquisitions. For single-rotation acquisitions, the method ensures to perform as good as FBP with arbitrarily coarse angular sampling in planar geometries, and provides a different approximation from the Feldkamp-Davis-Kress (FDK) algorithm in the cone-beam geometry. Although we used it to emulate a virtual bow-tie, our dual-rotation acquisition framework is intrinsically related to region-of-interest (ROI) imaging through the truncated acquisition. With few or no modification of the proposed reconstruction methods, we successfully addressed the problem of ROI imaging in the context of dual-rotation acquisitions.

« Tout le monde le dit, cela doit être vrai » Science et croyances coexistent tout au long de ce manuscrit ainsi que dans notre quotidien. Elles se nourrissent l’une de l’autre et partagent la définition commune d’être ce que l’on tient pour vrai. Pourtant le reste des qualificatifs définissant l’une et l’autre sont diamétralement opposés. Alors que la science est fondée sur des observations objectives vérifiables et une méthodologie rigoureuse (evidence-based medicine), les croyances, sont quant à elles fondées sur des observations subjectives et non vérifiables et empruntes de biais cognitifs. Il semblait donc nécessaire de réaliser une enquête philosophique et scientifique à la recherche de la vérité et ayant pour idéal la connaissance. L’objectif de ce travail de thèse est d’analyser sept croyances populaires issues du domaine de la santé sous le regard de la science à travers une étude narrative de la littérature. Sur les sept croyances présentées dans ce manuscrit, aucune n’a été validée scientifiquement et trois peuvent conduire à des modifications de comportements ayant un impact délétère sur la santé. Outre le rétablissement de la vérité qui à elle seule apparaît comme une raison suffisante, combattre les idées reçues ou les croyances populaires en matière de santé s’avère nécessaire lorsqu’elles conduisent les individus à adopter des comportements ou des attitudes néfastes. Le médecin traitant est un interlocuteur à privilégier. Malgré toutes les sources d’information possibles, il reste le premier vers qui se tourner en cas de question.

We study the zeros sets of functions in the Dirichlet space. Using Carleson formula for Dirichlet integral, we obtain some new families of zero sets. We also show that any closed subset of $E \subset \TT$ with logarithmic capacity zero is the accumulation points of the zeros of a function in the Dirichlet space. The zeros satisfy a growth restriction which depends on $E$.

Introduction : La carence en fer est une comorbidité fréquente dans l'insuffisance cardiaque chronique. La Société Européenne de Cardiologie (ESC) recommande son dépistage systématique et son traitement chez le patient insuffisant cardiaque à fraction d'éjection réduite par supplémentation en fer intraveineux pour améliorer les symptômes d'insuffisance cardiaque et la qualité de vie. Les données de la littérature sur les pratiques des médecins généralistes (MG) concernant le dépistage et la prise en charge de la carence en fer chez le patient insuffisant cardiaque sont insuffisantes. Matériels et méthodes : Nous avons réalisé une étude descriptive transversale observationnelle afin d'étudier les pratiques des médecins généralistes en matière de dépistage et de prise en charge de la carence en fer chez le patient insuffisant cardiaque. Un questionnaire d'enquête a été diffusé aux médecins généralistes exerçant une activité libérale en Loire-Atlantique et les réponses ont été collectées entre le 1er juin 2024 et le 29 septembre 2024. Résultats : Nous avons obtenu 50 réponses. Le dépistage de la carence en fer était insuffisant. Seuls quatre médecins donnaient la bonne définition de la carence en fer. Si la majorité des médecins répondaient traiter la carence en fer chez le patient insuffisant cardiaque, seuls 10% prescrivaient une supplémentation intraveineuse en première intention. La question de la balance bénéfice/risque de la perfusion, la mauvaise adhésion aux recommandations européennes, le coût de la perfusion et le manque de connaissance sont apparus comme des freins à l'application des recommandations. La possibilité de recourir facilement à l'hospitalisation de jour a été proposée par les médecins généralistes répondants. Conclusion : Notre étude a mis en évidence une application insuffisante des recommandations sur le dépistage et la prise en charge de la carence en fer chez le patient insuffisant cardiaque chronique. Une meilleure organisation du parcours de soin, et la résolution des freins à l'application de ces recommandations par les MG sont des pistes d'amélioration de prise en charge.

The framework for this work is the development of a new space propulsion technology. The device is based on the cyclotron resonance phenomenon to heat a plasma using microwaves. This work aims at simulating for the first time the magnetized plasma inside an Electron Cyclotron Resonance (ECR) thruster with self-consistent calculations of the electromagnetic fields to gain insight into the thruster's working principles. An electromagnetic solver for Maxwell's equations was developed based on the Constrained Interpolation Profile (CIP) method to simulate the electron-microwave interaction in a quasi-1D (1D3V) model of the thruster. This semi-Lagrangian method enables the use of large time steps in planar 1D to 3D cases while using an explicit formulation. However, the thruster modeling in a 2D cylindrical coordinate system (2D3V) faced the problem that the scheme was still limited by the Courant-Friedrichs-Lewy (CFL) condition. Therefore, we developed a procedure to overcome this constraint and extend the ability of this method to handle CFL greater than one in 2D axisymmetric domains. A ghost node method was also proposed to deal with boundary conditions such as the singularity on the axis or the perfectly conducting walls. The solvers were integrated into the electrostatic Particle-In-Cell/Monte-Carlo Module (PIC-MCC) code developed at Onera. They allowed the self-consistent electromagnetic full-PIC simulations of the ECR thruster in 1D and 2D axisymmetric. The results provided insight into the mechanisms affecting the plasma, like its heating and confinement, the energy lost by collisions and at the thruster's walls by cross-field diffusion, and the possibility of mode conversion for the microwaves due to its interaction with the plasma. In the 1D3V model, we show that the electron's energy perpendicular to the magnetic field lines increased near the heating zone and has a second unexpected peak in the nozzle due to the confinement of highly energetic electrons and loss at the close end of the thruster of low energy electrons. We carried out a parametric analysis with this model that allowed us to understand better the influence of some of the thruster's parameters on its performance and assess the sensibility of our model to have a more detailed view of the validity of the results. The cross-field diffusion towards the thruster's walls appeared as a dominant mechanism for energy lost over the collisions between the charged particles and the neutral background. The results of this research work will contribute to the efforts of the propulsion community to improve this technology.

Les succès cliniques rencontrés par les thérapies visant CTLA-4 et PD1 ont ouvert une nouvelle voie thérapeutique ciblant les checkpoints immunitaires et constituent une avancée scientifique majeure dans le traitement des cancers. Afin d’étudier in vivo ces nouvelles thérapies pour poursuivre leur développement, il est nécessaire de déterminer des paramètres permettant de caractériser la réponse immunitaire induite suite à l’administration d’inhibiteurs de ces checkpoints immunitaires (ICI). Dans ce projet, les analyses se sont portées sur trois modèles de tumeur, à savoir 4T1, EMT-6 et CT26 et les checkpoints immunitaires ciblés sont PD1, PD-L1, 4-1BB et CTLA-4. Les paramètres évalués sont principalement l’infiltration lymphocytaire intratumorale et intranodale et le profil d’expression de 25 cytokines et chimiokines circulantes. L’efficacité des traitements administrés est réelle et semble être corrélée à un ratio T CD8+ effecteurs / T CD4+ FoxP3+ régulateurs élevé au sein des tumeurs. Toutefois, comme en clinique, cette efficacité est individu et tumeur-dépendante. En effet, les animaux d’un même groupe et les trois modèles entre eux ne réagissent pas de la même manière, notamment 4T1 qui est particulièrement résistant. De plus, les animaux porteurs spécifiquement de cette tumeur présentent un risque élevé de mortalité suite à des injections répétées d’anticorps ciblant PD-L1, PD1 ou CTLA-4. Cette létalité semble être corrélée à un relargage massif de cytokines induisant une réaction de type anaphylaxie qui aboutit à la mort de l’animal. Afin de dépasser cette résistance et de diminuer la mortalité, plusieurs combinaisons d’ICI ont été testées dans ce modèle. Il en ressort principalement que les combinaisons associant un ICI avec un anticorps anti-4-1BB induisent très peu de mortalité comparées aux monothérapies. Ce bénéfice est associé à une augmentation de l’infiltration lymphocytaire pulmonaire et à une modulation du profil d’expression cytokinique des monothérapies. Les comparaisons entre EMT-6 et 4T1, deux modèles relativement proches du point de vue histologique, permettent de mettre en évidence des profils d’expression cytokinique différents impliquant une réponse dépendante de la tumeur. Dans les deux cas, l’anticorps anti-4-1BB module la réponse immunitaire pour la rendre plus efficace. La poursuite de la caractérisation de ces réponses est longue et difficile en raison de la complexité du système immunitaire et nécessite une capacité d’analyse importante. Ce projet apporte sa pierre à l’édifice dans la compréhension des mécanismes mis en jeu et notamment dans l’intérêt porté sur 4-1BB. La poursuite des investigations pourrait permettre à terme, dans le cadre d’un essai clinique, de maintenir les patients sous immunothérapie grâce à l’administration d’un anticorps anti-4-1BB dès l’apparition d’effets secondaires importants.

Polycrystalline samples of a Fe-Mn-Si-Cr-Ni shape memory alloy containing a 70% fraction of thermal [MATH]-martensite have been studied by H.R.E.M. Images taken along a [MATH] axis clearly show, at the atomic level, the layered substructure of larger [MATH]-bands. By analysing numerically processed images of elementary [MATH]-laminate tips, the [MATH] interface could be described by a periodic array of 30° and 90° Shockley partials in a 2:1 ratio, leading to self-accommodation of thermal [MATH]-martensite at the finest scale.