Network structures and development dynamics - from the Industrial Revolution to the Energy Transition
Networks are crucial components of complex societies and underlie successful climate-energy strategies. Nevertheless they remain relatively understudied and insufficiently understood in their dynamics as well as in their relation to resource consumption and economic prosperity.
In this doctoral project, several historical cases of physical network will be explored from an industrial ecology standpoint and in relation to energy consumption. The project will address complexity in sociotechnical network structures and uses based on a complex systems modelling approach associating statistical physics (graph theory), geography and economic history. The project will mainly focus on the transportation and energy networks and their entanglement.
A first target will be railway networks that progressively grew during the 19th century in relation to coal extraction, trade and use. Railway networks are intertwined with early-industrial sociotechnical development and paved the way to the development of road networks in the 20th century in particular on the basis of complex oil networks. The study will address the dual role of railways and road networks in the transportation of both passengers and freight of energy and materials. The growth rates, interconnections and key metrics of these networks will be jointly analyzed and compared to an equivalent analysis of electricity grids which are currently under study by members of the PhD proposal team.
Methods for the Rapid Detection of Gravitational Events from LISA Data
The thesis focuses on the development of rapid analysis methods for the detection and characterization of gravitational waves, particularly in the context of the upcoming LISA (Laser Interferometer Space Antenna) space mission planned by ESA around 2035. Data analysis involves several stages, one of the first being the rapid analysis “pipeline,” whose role is to detect new events and to characterize them. The final aspect concerns the rapid estimation of the sky position of the gravitational wave source and their characteristic time, such as the coalescence time in the case of black hole mergers. These analysis tools constitute the low-latency analysis pipeline.
Beyond its value for LISA, this pipeline also plays a crucial role in the rapid follow-up of events detected by electromagnetic observations (ground or space-based observatories, from radio waves to gamma rays). While fast analysis methods have been developed for ground-based interferometers, the case of space-borne interferometers such as LISA remains an area to be explored. Thus, a tailored data processing method will have to consider the packet-based data transmission mode, requiring event detection from incomplete data. From data affected by artifacts such as glitches, these methods must enable the detection, discrimination, and analysis of various sources.
In this thesis, we propose to develop a robust and effective method for the early detection of massive black hole binaries (MBHBs). This method should accommodate the data flow expected for LISA, process potential artifacts (e.g., non-stationary noise and glitches), and allow the generation of alerts, including a detection confidence index and a first estimate of the source parameters (coalescence time, sky position, and binary mass); such a rapid initial estimate is essential for optimally initializing a more accurate and computationally expensive parameter estimation.
Influence of a nano-antenna on the intersystem crossing rate of a single molecule
As part of the continuation of the ANR JCJC PlasmonISC project, we propose a thesis subject mainly experimental in nano-photonics. The objective of the thesis is to study the influence of a nano-antenna (plasmonic, magnetic or dielectric) on the rate governing the photophysics of fluorescence emission from a single molecule, with a particular interest in the intersystem crossing rate. We have developed a dedicated optical bench combining optical and atomic force microscopy, an experimental procedure, as well as signal processing tools, showing encouraging first results with a dielectric tip. We wish to continue to explore the single molecule/nano-antenna interaction with other types of tips generating other physical effects. The ability to control the transition to the triplet state is of great interest for single photon sources, organic light emitting diodes, and in chemistry.
Unveiling the Universal Coupling Between Accretion and Ejection: From Microquasars to Extragalactic Transients
This PhD project investigates the universal coupling between accretion and ejection, the fundamental processes through which black holes and neutron stars grow and release energy. Using microquasars as nearby laboratories, the project will study how variations in accretion flows produce relativistic jets, and how these mechanisms scale up to supermassive black holes in tidal disruption events (TDEs).
Accretion–ejection coupling drives energy feedback that shapes galaxy formation and evolution, yet its physical origin remains poorly understood. The candidate will combine multi-wavelength observations—from SVOM (X-ray/optical) and new radio facilities (MeerKAT, SKA precursors)—to perform time-resolved analyses linking accretion states to jet emission.
Recent missions such as Einstein Probe and the Vera Rubin Observatory (LSST) will greatly expand the sample of transients, including jetted TDEs, enabling new tests of jet-launching physics across mass and time scales.
Working within the CEA/IRFU team, a major SVOM partner, the student will participate in real-time transient detection and multi-wavelength follow-up, while also exploiting archival data to provide long-term context. This project will train the candidate in high-energy astrophysics, radio astronomy, and data-driven discovery, contributing to a unified understanding of accretion, jet formation, and cosmic feedback.
Explainable AI for interpretation of Small Angle Scattering
The PhD will be conducted in two laboratories at Paris-Saclay: one group with expertise in artificial intelligence developed over many years, MIA-PS (INRAE), and another in the physics of matter – soft matter, biology – MMB-LLB (CEA/CNRS).
Small-Angle Scattering techniques (X-rays, neutrons, light) involve a constantly growing community, particularly active in France, especially in soft matter and biology. The transition of data from reciprocal space to real space is achieved via different models – in which the MMB group is an expert – whether concerning shape – sphere, rod, platelet, polymer chain – or interactions – attraction, aggregation, repulsion, arrangement. Furthermore, more complex structures, such as proteins or irregular aggregates, require computational or empirical approaches. In all cases, the results are not unequivocal. This is particularly challenging for research groups new to the technique.
In this thesis, thanks to MIA-PS's expertise in AI (machine learning, optimization, visualization), the focus will be on developing explainable AI methods. Part of the modeling involves explained mathematical and physical models, while another part relies on so-called "black box" models, which will be progressively explained. The doctoral candidate will have access to data from three use cases provided by the LLB, and to their experts, to develop a generic methodology. A first step could be based on the globally shared software SasView, a treasure trove of explicit models. We have already received a positive response from the SasView developers, which could therefore serve as a dissemination tool. A valuable contribution will be the access to complementary DPA measurements via the LLB platforms and the SOLEIL and ESRF synchrotrons.
Subsequently, a component focusing on human-computer interaction—ensuring that users remain fully responsible for constructing a physico-chemical-biological explanation—can be implemented. MIA-PS is also an expert in advanced interactive visualization methods.
This project therefore combines highly advanced developments in computer science with a wealth of real-world systems chosen for their originality and, of course, their potential applications.
Aurorae are well known optical phenomena in the Solar System planets. Aurorae have great diagnostic value, as their emissions reveal the planets’ atmospheric compositions, the occurrence of magnetic fields and the solar wind conditions at the planet’s orbit. Looking for aurorae on exoplanets and brown dwarfs is the next frontier. A first breakthrough in this direction has occurred recently, with the detection of a CH4 emission attributed to auroral excitation on the brown dwarf W1935. This detection, and the prospects of observing other auroral features with existent and upcoming telescopes, is what motivates this project. In particular, we will build the first model dedicated to investigate CH4 and H3+ auroral emission on exoplanets and brown dwarfs. The model will be used to investigate the conditions at W1935, and to predict the detectability of aurorae on other sub-stellar objects.
New concepts for cold neutron reflectors
The CEA and the CNRS have launched an initiative to design a new neutron source using low-energy proton accelerators, the ICONE project [1]. The goal is to build a facility that will provide an instrumental suite of about ten spectrometers available to the French and European scientific community. Alongside ICONE, the LLB is also participating in HiCANS R&D work on the construction of a platform in Bilbao to facilitate European collaborations.Neutron scattering experiments require thermal and cold neutrons. The design of the moderator is therefore a crucial component of the project to maximize the source's performance.
One avenue for improving the moderator performances is to enhance the efficiency of the reflector, and more specifically, the cold neutron reflector. In this study, we propose to investigate the specific scattering properties of cold neutrons on nanostructured materials. Indeed, cold neutrons have long wavelengths (> 0.4 nm) and can therefore be coherently scattered by nanostructured materials. Scattering efficiency is not only amplified by coherent scattering effects, but it is potentially possible to direct this scattering if the reflecting material is anisotropic. This control over the scattering direction can further increase the moderator's brightness.
The first part of the work will consist of identifying the most promising nanostructured materials and modeling their cold neutron reflectivity performance. In a second step, these materials will be shaped and their properties characterized using neutron scattering devices at neutron scattering facilities such as the ILL in Grenoble or the PSI in Switzerland.
Toughening random lattice metamaterials with structure heterogeneities
To reduce the environmental and/or the energetic impact of vehicles, a favored method is to decrease the mass of prime materials used to build them, that being done without hindering their mechanical performances. In this field, the use of mechanical metamaterials has been a major breakthrough. These metamaterials, generally created using additive manufacturing techniques, have a microscopic truss structure. They are porous by design, and thus very lightweight, and the distribution of their microscopic beams or tubes (i.e. their architecture) can be chosen to make them as stiff as possible, making them choice candidates for high technology applications where the rigidity-density ratio is paramount, such as aerospatial research (https://en.wikipedia.org/wiki/Metallic_microlattice).
For the most part however, metamaterials that have been designed up to now present periodical architectures. As a consequence, their mechanical behavior is inherently anisotropic, which makes them difficult to model using material mechanics conventional approaches, and strongly limits their usage in various possible fields of applications. In recent works, we have developped a new class of microlattice metamaterials with a random spatial distribution of beams, generated with a combination of random close packing and Delaunay triangulation algorithm then 3D-manufactured. These metamaterials show an isotropic mechanical behavior, and their stiffness-density ratio reaches the theoretical limit for porous materials. They are neverheless still fragile and subject to fracture and yielding.
The aim of this PhD project is to toughen these metamaterials based on techniques and mechanisms from polymer and soft matter physics. Our hypothesis is that including in a controlled statistical way structure heterogeneities, at the node level by modulating the connectivity or at the beam level by changing their section or shape, can allow toughening of the metamaterial. Indeed, localized heterogeneities can introduce mechanical dissipations in the network at various scales. The work of this project will consist in experiementally characterizing the mechanical properties of the metamaterials and to compare them to their homogeneous equivalent, and to describe their fracture resistance. Mechanical tests will be performed on an experimental setup conceived in the SPHYNX group. Analysis of the local and global deformation will be performed using different experiemental methods, in order to detect micro crack events with precision. An additionnal theoretical approach completed by numerical simulations based on fuse network and random beam models can also be discussed.
A strong interest for instrumentation and teamwork is requested for this project with a major experimental component. Proficiencies in experimental mechanics, material sciences and/or statistical physics are desirable. Some knowledge in modelization and numerical simulations are a bonus without being required. This project has both fundamental and applied interests and can help the student find prospects both in academia and in industrial opportunities.
CONTEXT: strain - texture neutron instrumentation for ICONE
The CEA and the CNRS have launched an initiative to design a new neutron source using low-energy proton accelerators, the ICONE project. The objective is to build a facility that will offer an instrumental suite of about ten spectrometers available to the French and European scientific community. The project is currently in the Preliminary Design phase, with the aim of refining as much as possible all technical aspects.
We are proposing a PhD thesis on the modeling and development of a new neutron scattering spectrometer for measuring textures and stresses in materials. This technique makes it possible to probe residual stresses in materials after machining, heat treatment, and/or use, and to measure the crystallographic anisotropy of alloys to exploit the induced mechanical properties.
Part of the work will take advantage of the start-up of the DREAM and MAGIC spectrometers at ESS in Sweden, in which the LLB participated in the construction, so that the candidate can become familiar with time-of-flight neutron scattering techniques (measurements and data analysis).
In the second part of this work, we propose to implement statistical modulation techniques for the construction of an instrument, CONTEXT, on ICONE, which will allow to best exploit the potential of ICONE's long pulses. The objective will be to create a digital twin of the future instrument using various Monte Carlo simulation tools.
Endothelial-fibroblast interactions in diabetic foot ulcer: deciphering the intercellular communication responsible for the chronic wound persistence
Diabetic foot ulcer (DFU), a severe complication of diabetes affecting approximately 18.6 million people worldwide each year, is associated with high rates of amputation and mortality. Like other chronic wounds, DFUs exhibit impaired healing due to a dysregulated cascade of cellular signalling and behavioural events that normally ensure rapid closure of the skin barrier. Among the key cellular players, fibroblasts and endothelial cells are central to the proliferative and remodelling phases of wound repair – processes that are notably dysfunctional in chronic wounds. Although endothelial-fibroblast crosstalk is recognized as an essential driver of normal skin healing, the specific mechanisms governing their interaction in DFU is poorly understood.
The main objective of this PhD project is to decipher the intercellular communication between endothelial cells and fibroblasts that underlies the chronicity of DFU. Particular attention will be devoted to extracellular vesicle-associated microRNAs (miRNAs), which are pivotal regulators of intercellular communication through modulation of gene expression in recipient cells. By characterizing the repertoire of pro- and anti-healing miRNAs exchanged between endothelial cells and fibroblasts, this project seeks to uncover novel molecular targets and therapeutic strategies to promote wound repair in diabetic foot ulcers.