ERC FUNDED PROJECTS

The paradigm of the structure-function relationship in proteins is outdated. Biological macromolecules and supramolecular assemblies are highly dynamic objects. Evidence that their motions are of utmost importance to their functions is regularly identified. The understanding of the physical chemistry of biological processes at an atomic level has to rely not only on the description of structure but also on the characterization of molecular motions. The investigation of protein motions will be undertaken with a very innovative methodological approach in nuclear magnetic resonance relaxation. In order to widen the ranges of frequencies at which local motions in proteins are probed, we will first use and develop new techniques for a prototype shuttle system for the measurement of relaxation at low fields on a high-field NMR spectrometer. Second, we will develop a novel system: a set of low-field NMR spectrometers designed as accessories for high-field spectrometers. Used in conjunction with the shuttle, this system will offer (i) the sensitivity and resolution (i.e. atomic level information) of a high-field spectrometer (ii) the access to low fields of a relaxometer and (iii) the ability to measure a wide variety of relaxation rates with high accuracy. This system will benefit from the latest technology in homogeneous permanent magnet development to allow a control of spin systems identical to that of a high-resolution probe. This new apparatus will open the way to the use of NMR relaxation at low fields for the refinement of protein motions at an atomic scale. Applications of this novel approach will focus on the bright side of protein dynamics: (i) the largely unexplored dynamics of intrinsically disordered proteins, and (ii) domain motions in large proteins. In both cases, we will investigate a series of diverse protein systems with implications in development, cancer and immunity.

1 462 080 €

Start date: 2012-01-01, End date: 2017-12-31

The fundamental 3D-BioMat project aims at providing a biomineralization model to explain the formation of microscopic calcareous single-crystals produced by living organisms. Although these crystals present a wide variety of shapes, associated to various organic materials, the observation of a nanoscale granular structure common to almost all calcareous crystallizing organisms, associated to an extended crystalline coherence, underlies a generic biomineralization and assembly process. A key to building realistic scenarios of biomineralization is to reveal the crystalline architecture, at the mesoscale, (i. e., over a few granules), which none of the existing nano-characterization tools is able to provide. 3D-BioMat is based on the recognized PI’s expertise in the field of synchrotron coherent x-ray diffraction microscopy. It will extend the PI’s disruptive pioneering microscopy formalism, towards an innovative high-throughput approach able at giving access to the 3D mesoscale image of the crystalline properties (crystal-line coherence, crystal plane tilts and strains) with the required flexibility, nanoscale resolution, and non-invasiveness. This achievement will be used to timely reveal the generics of the mesoscale crystalline structure through the pioneering explorations of a vast variety of crystalline biominerals produced by the famous Pinctada mar-garitifera oyster shell, and thereby build a realistic biomineralization scenario. The inferred biomineralization pathways, including both physico-chemical pathways and biological controls, will ultimately be validated by comparing the mesoscale structures produced by biomimetic samples with the biogenic ones. Beyond deciphering one of the most intriguing questions of material nanosciences, 3D-BioMat may contribute to new climate models, pave the way for new routes in material synthesis and supply answers to the pearl-culture calcification problems.

1 966 429 €

Start date: 2017-03-01, End date: 2022-02-28

Label-free optical nanoscopy, free from photobleaching and photochemical toxicity of fluorescence labels and yielding 3D morphological resolution of <50 nm, is the future of live cell imaging. 3D-nanoMorph breaks the diffraction barrier and shifts the paradigm in label-free nanoscopy, providing isotropic 3D resolution of <50 nm. To achieve this, 3D-nanoMorph performs non-linear inverse scattering for the first time in nanoscopy and decodes scattering between sub-cellular structures (organelles). 3D-nanoMorph innovatively devises complementary roles of light measurement system and computational nanoscopy algorithm. A novel illumination system and a novel light collection system together enable measurement of only the most relevant intensity component and create a fresh perspective about label-free measurements. A new computational nanoscopy approach employs non-linear inverse scattering. Harnessing non-linear inverse scattering for resolution enhancement in nanoscopy opens new possibilities in label-free 3D nanoscopy. I will apply 3D-nanoMorph to study organelle degradation (autophagy) in live cancer cells over extended duration with high spatial and temporal resolution, presently limited by the lack of high-resolution label-free 3D morphological nanoscopy. Successful 3D mapping of nanoscale biological process of autophagy will open new avenues for cancer treatment and showcase 3D-nanoMorph for wider applications. My cross-disciplinary expertise of 14 years spanning inverse problems, electromagnetism, optical microscopy, integrated optics and live cell nanoscopy paves path for successful implementation of 3D-nanoMorph.

1 499 999 €

Start date: 2019-07-01, End date: 2024-06-30

Several observed anomalies in neutrino oscillation data can be explained by a hypothetical fourth neutrino separated from the three standard neutrinos by a squared mass difference of a few eV2. This hypothesis can be tested with a PBq (ten kilocurie scale) 144Ce antineutrino beta-source deployed at the center of a large low background liquid scintillator detector, such like Borexino, KamLAND, and SNO+. In particular, the compact size of such a source could yield an energy-dependent oscillating pattern in event spatial distribution that would unambiguously determine neutrino mass differences and mixing angles. The proposed program aims to perform the necessary research and developments to produce and deploy an intense antineutrino source in a large liquid scintillator detector. Our program will address the definition of the production process of the neutrino source as well as its experimental characterization, the detailed physics simulation of both signal and backgrounds, the complete design and the realization of the thick shielding, the preparation of the interfaces with the antineutrino detector, including the safety and security aspects.

1 500 000 €

Start date: 2012-10-01, End date: 2018-09-30

"The A2C2 project treats two major challenges in climate and atmospheric research: the time dependence of the climate attractor to external forcings (solar, volcanic eruptions and anthropogenic), and the attribution of extreme climate events occurring in the northern extra-tropics. The main difficulties are the limited climate information, the computer cost of model simulations, and mathematical assumptions that are hardly verified and often overlooked in the literature. A2C2 proposes a practical framework to overcome those three difficulties, linking the theory of dynamical systems and statistics. We will generalize the methodology of flow analogues to multiple databases in order to obtain probabilistic descriptions of analogue decompositions. The project is divided into three workpackages (WP). WP1 embeds the analogue method in the theory of dynamical systems in order to provide a metric of an attractor deformation in time. The important methodological step is to detect trends or persisting outliers in the dates and scores of analogues when the system yields time-varying forcings. This is done from idealized models and full size climate models in which the forcings (anthropogenic and natural) are known. A2C2 creates an open source toolkit to compute flow analogues from a wide array of databases (WP2). WP3 treats the two scientific challenges with the analogue method and multiple model ensembles, hence allowing uncertainty estimates under realistic mathematical hypotheses. The flow analogue methodology allows a systematic and quasi real-time analysis of extreme events, which is currently out of the reach of conventional climate modeling approaches. The major breakthrough of A2C2 is to bridge the gap between operational needs (the immediate analysis of climate events) and the understanding long-term climate changes. A2C2 opens new research horizons for the exploitation of ensembles of simulations and reliable estimates of uncertainty."

1 491 457 €

Start date: 2014-03-01, End date: 2019-02-28

The rupture of an Aortic Aneurysm (AA), which is often lethal, is a mechanical phenomenon that occurs when the wall stress state exceeds the local strength of the tissue. Our current understanding of arterial rupture mechanisms is poor, and the physics taking place at the microscopic scale in these collagenous structures remains an open area of research. Understanding, modelling, and quantifying the micro-mechanisms which drive the mechanical response of such tissue and locally trigger rupture represents the most challenging and promising pathway towards predictive diagnosis and personalized care of AA. The PI's group was recently able to detect, in advance, at the macro-scale, rupture-prone areas in bulging arterial tissues. The next step is to get into the details of the arterial microstructure to elucidate the underlying mechanisms. Through the achievements of AArteMIS, the local mechanical state of the fibrous microstructure of the tissue, especially close to its rupture state, will be quantitatively analyzed from multi-photon confocal microscopy and numerically reconstructed to establish quantitative micro-scale rupture criteria. AArteMIS will also address developing micro-macro models which are based on the collected quantitative data. The entire project will be completed through collaboration with medical doctors and engineers, experts in all required fields for the success of AArteMIS. AArteMIS is expected to open longed-for pathways for research in soft tissue mechanobiology which focuses on cell environment and to enable essential clinical applications for the quantitative assessment of AA rupture risk. It will significantly contribute to understanding fatal vascular events and improving cardiovascular treatments. It will provide a tremendous source of data and inspiration for subsequent applications and research by answering the most fundamental questions on AA rupture behaviour enabling ground-breaking clinical changes to take place.

1 499 783 €

Start date: 2015-04-01, End date: 2020-03-31

The emergence of life is one of the most fascinating and yet largely unsolved questions in the natural sciences, and thus a significant challenge for scientists from many disciplines. There is growing evidence that ribonucleic acid (RNA) polymers, which are capable of genetic information storage and self-catalysis, were involved in the early forms of life. But despite recent progress, RNA synthesis without biological machineries is very challenging. The current project aims at understanding how to synthesize RNA in abiotic conditions. I will solve problems associated with three critical aspects of RNA formation that I will rationalize at a molecular level: (i) accumulation of precursors, (ii) formation of a chemical bond between RNA monomers, and (iii) tolerance for alternative backbone sugars or linkages. Because I will study problems ranging from the formation of chemical bonds up to the stability of large biopolymers, I propose an original computational multi-scale approach combining techniques that range from quantum calculations to large-scale all-atom simulations, employed together with efficient enhanced-sampling algorithms, forcefield improvement, cutting-edge analysis methods and model development. My objectives are the following: 1 • To explain why the poorly-understood thermally-driven process of thermophoresis can contribute to the accumulation of dilute precursors. 2 • To understand why linking RNA monomers with phosphoester bonds is so difficult, to understand the molecular mechanism of possible catalysts and to suggest key improvements. 3 • To rationalize the molecular basis for RNA tolerance for alternative backbone sugars or linkages that have probably been incorporated in abiotic conditions. This unique in-silico laboratory setup should significantly impact our comprehension of life’s origin by overcoming major obstacles to RNA abiotic formation, and in addition will reveal significant orthogonal outcomes for (bio)technological applications.

1 497 031 €

Start date: 2018-02-01, End date: 2023-01-31

Actanthrope intends to promote a neuro-robotics perspective to explore original models of anthropomorphic action. The project targets contributions to humanoid robot autonomy (for rescue and service robotics), to advanced human body simulation (for applications in ergonomics), and to a new theory of embodied intelligence (by promoting a motion-based semiotics of the human action). Actions take place in the physical space while they originate in the –robot or human– sensory-motor space. Geometry is the core abstraction that makes the link between these spaces. Considering that the structure of actions inherits from that of the body, the underlying intuition is that actions can be segmented within discrete sub-spaces lying in the entire continuous posture space. Such sub-spaces are viewed as symbols bridging deliberative reasoning and reactive control. Actanthrope argues that geometric approaches to motion segmentation and generation as promising and innovative routes to explore embodied intelligence: - Motion segmentation: what are the sub-manifolds that define the structure of a given action? - Motion generation: among all the solution paths within a given sub-manifold, what is the underlying law that makes the selection? In Robotics these questions are related to the competition between abstract symbol manipulation and physical signal processing. In Computational Neuroscience the questions refer to the quest of motion invariants. The ambition of the project is to promote a dual perspective: exploring the computational foundations of human action to make better robots, while simultaneously doing better robotics to better understand human action. A unique “Anthropomorphic Action Factory” supports the methodology. It aims at attracting to a single lab, researchers with complementary know-how and solid mathematical background. All of them will benefit from unique equipments, while being stimulated by four challenges dealing with locomotion and manipulation actions.

2 500 000 €

Start date: 2014-01-01, End date: 2018-12-31

"Computer vision is concerned with the automated interpretation of images and video streams. Today's research is (mostly) aimed at answering queries such as ""Is this a picture of a dog?"", (classification) or sometimes ""Find the dog in this photo"" (detection). While categorisation and detection are useful for many tasks, inferring correct class labels is not the final answer to visual recognition. The categories and locations of objects do not provide direct understanding of their function i.e., how things work, what they can be used for, or how they can act and react. Such an understanding, however, would be highly desirable to answer currently unsolvable queries such as ""Am I in danger?"" or ""What can happen in this scene?"". Solving such queries is the aim of this proposal. My goal is to uncover the functional properties of objects and the purpose of actions by addressing visual recognition from a different and yet unexplored perspective. The main novelty of this proposal is to leverage observations of people, i.e., their actions and interactions to automatically learn the use, the purpose and the function of objects and scenes from visual data. The project is timely as it builds upon the two key recent technological advances: (a) the immense progress in visual recognition of objects, scenes and human actions achieved in the last ten years, as well as (b) the emergence of a massive amount of public image and video data now available to train visual models. ACTIVIA addresses fundamental research issues in automated interpretation of dynamic visual scenes, but its results are expected to serve as a basis for ground-breaking technological advances in practical applications. The recognition of functional properties and intentions as explored in this project will directly support high-impact applications such as detection of abnormal events, which are likely to revolutionise today's approaches to crime protection, hazard prevention, elderly care, and many others."

1 497 420 €

Start date: 2013-01-01, End date: 2018-12-31

The aim of this project is the realisation of efficient mid-infrared and THz optoelectronic emitters. This work is motivated by the fact that the spontaneous emission in this frequency range is characterized by an extremely long lifetime when compared to non-radiative processes, giving rise to devices with very low quantum efficiency. To this end we want to develop hybrid light-matter systems, already well known in quantum optics, within optoelectronics devices, that will be driven by electrical injection. With this project we want to extend the field of optoelectronics by introducing some of the concepts of quantum optic, particularly the light-matter strong coupling, into semiconductor devices. More precisely this project aims at the implementation of novel optoelectronic emitters operating in the strong coupling regime between an intersubband excitation of a two-dimensional electron gas and a microcavity photonic mode. The quasiparticles issued from this coupling are called intersubband polaritons. The major difficulties and challenges of this project, do not lay in the observation of these quantum effects, but in their exploitation for a specific function, in particular an efficient electrical to optical conversion. To obtain efficient quantum emitters in the THz frequency range we will follow two different approaches: - In the first case we will try to exploit the additional characteristic time of the system introduced by the light-matter interaction in the strong (or ultra-strong) coupling regime. - The second approach will exploit the fact that, under certain conditions, intersubband polaritons have a bosonic character; as a consequence they can undergo stimulated scattering, giving rise to polaritons lasers as it has been shown for excitonic polaritons.

1 761 000 €

Start date: 2010-05-01, End date: 2015-04-30

Fundamental interactions in nature are well described by quantum gauge fields in 4 space-time dimensions (4d). When the strength of gauge interaction is weak the Feynman perturbation techniques are very efficient for the description of most of the experimentally observable consequences of the Standard model and for the study of high energy processes in QCD. But in the intermediate and strong coupling regime, such as the relatively small energies in QCD, the perturbation theory fails leaving us with no reliable analytic methods (except the Monte-Carlo simulation). The project aims at working out new analytic and computational methods for strongly coupled gauge theories in 4d. We will employ for that two important discoveries: 1) the gauge-string duality (AdS/CFT correspondence) relating certain strongly coupled gauge Conformal Field Theories to the weakly coupled string theories on Anty-deSitter space; 2) the solvability, or integrability of maximally supersymmetric (N=4) 4d super Yang-Mills (SYM) theory in multicolor limit. Integrability made possible pioneering exact numerical and analytic results in the N=4 multicolor SYM at any coupling, effectively summing up all 4d Feynman diagrams. Recently, we conjectured a system of functional equations - the AdS/CFT Y-system – for the exact spectrum of anomalous dimensions of all local operators in N=4 SYM. The conjecture has passed all available checks. My project is aimed at the understanding of origins of this, still mysterious integrability. Deriving the AdS/CFT Y-system from the first principles on both sides of gauge-string duality should provide a long-awaited proof of the AdS/CFT correspondence itself. I plan to use the Y-system to study the systematic weak and strong coupling expansions and the so called BFKL limit, as well as for calculation of multi-point correlation functions of N=4 SYM. We hope on new insights into the strong coupling dynamics of less supersymmetric gauge theories and of QCD.

1 456 140 €

Start date: 2013-11-01, End date: 2018-10-31

Arctic sea ice decline is the exponent of the rapidly transforming Arctic climate. The ensuing local and global implications can be understood by studying past climate transitions, yet few methods are available to examine past Arctic sea ice cover, severely restricting our understanding of sea ice in the climate system. The decline in Arctic sea ice cover is a ‘canary in the coalmine’ for the state of our climate, and if greenhouse gas emissions remain unchecked, summer sea ice loss may pass a critical threshold that could drastically transform the Arctic. Because historical observations are limited, it is crucial to have reliable proxies for assessing natural sea ice variability, its stability and sensitivity to climate forcing on different time scales. Current proxies address aspects of sea ice variability, but are limited due to a selective fossil record, preservation effects, regional applicability, or being semi-quantitative. With such restraints on our knowledge about natural variations and drivers, major uncertainties about the future remain. I propose to develop and apply a novel sea ice proxy that exploits genetic information stored in marine sediments, sedimentary ancient DNA (sedaDNA). This innovation uses the genetic signature of phytoplankton communities from surface waters and sea ice as it gets stored in sediments. This wealth of information has not been explored before for reconstructing sea ice conditions. Preliminary results from my cross-disciplinary team indicate that our unconventional approach can provide a detailed, qualitative account of past sea ice ecosystems and quantitative estimates of sea ice parameters. I will address fundamental questions about past Arctic sea ice variability on different timescales, information essential to provide a framework upon which to assess the ecological and socio-economic consequences of a changing Arctic. This new proxy is not limited to sea ice research and can transform the field of paleoceanography.

2 615 858 €

Start date: 2019-08-01, End date: 2024-07-31

A massive and ever growing amount of digital image and video content is available today, on sites such as Flickr and YouTube, in audiovisual archives such as those of BBC and INA, and in personal collections. In most cases, it comes with additional information, such as text, audio or other metadata, that forms a rather sparse and noisy, yet rich and diverse source of annotation, ideally suited to emerging weakly supervised and active machine learning technology. The ALLEGRO project will take visual recognition to the next level by using this largely untapped source of data to automatically learn visual models. The main research objective of our project is the development of new algorithms and computer software capable of autonomously exploring evolving data collections, selecting the relevant information, and determining the visual models most appropriate for different object, scene, and activity categories. An emphasis will be put on learning visual models from video, a particularly rich source of information, and on the representation of human activities, one of today's most challenging problems in computer vision. Although this project addresses fundamental research issues, it is expected to result in significant advances in high-impact applications that range from visual mining of the Web and automated annotation and organization of family photo and video albums to large-scale information retrieval in television archives.

2 493 322 €

Start date: 2013-04-01, End date: 2019-03-31

The field of disordered quantum gases is developing rapidly. Dramatic progress has been achieved recently and first experimental observation of one-dimensional Anderson localization (AL) of matterwaves has been reported using Bose-Einstein condensates in controlled disorder (in our group at Institut d'Optique and at LENS; Nature, 2008). This dramatic success results from joint theoretical and experimental efforts, we have contributed to. Most importantly, it opens unprecedented routes to pursue several outstanding challenges in the multidisciplinary field of disordered systems, which, after fifty years of Anderson localization, is more active than ever. This theoretical project aims at further developing the emerging field of disordered quantum gases towards novel challenges. Our aim is twofold. First, we will propose and analyze schemes where experiments on ultracold atoms can address unsolved issues: AL in dimensions higher than one, effects of inter-atomic interactions on AL, strongly-correlated disordered gases and quantum simulators for spin systems (spin glasses). Second, by taking into account specific features of ultracold atoms, beyond standard toy-models, we will raise and study new questions which have not been addressed before (eg long-range correlations of speckle potentials, finite-size effects, controlled interactions). Both aspects would open new frontiers to disordered quantum gases and offer new possibilities to shed new light on highly debated issues. Our main concerns are thus to (i) study situations relevant to experiments, (ii) develop new approaches, applicable to ultracold atoms, (iii) identify key observables, and (iv) propose new challenging experiments. In this project, we will benefit from the original situation of our theory team: It is independent but forms part of a larger group (lead by A. Aspect), which is a world-leader in experiments on disordered quantum gases, we have already developed close collaborative relationship with.

985 200 €

Start date: 2011-01-01, End date: 2015-12-31

Applied electrochemistry plays a key role in many technologies, such as batteries, fuel cells, supercapacitors or solar cells. It is therefore at the core of many research programs all over the world. Yet, fundamental electrochemical investigations remain scarce. In particular, electrochemistry is among the fields for which the gap between theory and experiment is the largest. From the computational point of view, there is no molecular dynamics (MD) software devoted to the simulation of electrochemical systems while other fields such as biochemistry (GROMACS) or material science (LAMMPS) have dedicated tools. This is due to the difficulty of accounting for complex effects arising from (i) the degree of metallicity of the electrode (i.e. from semimetals to perfect conductors), (ii) the mutual polarization occurring at the electrode/electrolyte interface and (iii) the redox reactivity through explicit electron transfers. Current understanding therefore relies on standard theories that derive from an inaccurate molecular-scale picture. My objective is to fill this gap by introducing a whole set of new methods for simulating electrochemical systems. They will be provided to the computational electrochemistry community as a cutting-edge MD software adapted to supercomputers. First applications will aim at the discovery of new electrolytes for energy storage. Here I will focus on (1) ‘‘water-in-salts’’ to understand why these revolutionary liquids enable much higher voltage than conventional solutions (2) redox reactions inside a nanoporous electrode to support the development of future capacitive energy storage devices. These selected applications are timely and rely on collaborations with leading experimental partners. The results are expected to shed an unprecedented light on the importance of polarization effects on the structure and the reactivity of electrode/electrolyte interfaces, establishing MD as a prominent tool for solving complex electrochemistry problems.

1 588 769 €

Start date: 2018-04-01, End date: 2023-03-31

I propose to use large clouds of cold Ytterbium atoms to observe Anderson localization of light in three dimensions, which has challenged theoreticians and experimentalists for many decades. After the prediction by Anderson of a disorder-induced conductor to insulator transition for electrons, light has been proposed as ideal non interacting waves to explore coherent transport properties in the absence of interactions. The development in experiments and theory over the past several years have shown a route towards the experimental realization of this phase transition. Previous studies on Anderson localization of light using semiconductor powders or dielectric particles have shown that intrinsic material properties, such as absorption or inelastic scattering of light, need to be taken into account in the interpretation of experimental signatures of Anderson localization. Laser-cooled clouds of atoms avoid the problems of samples used so far to study Anderson localization of light. Ab initio theoretical models, available for cold Ytterbium atoms, have shown that the mere high spatial density of the scattering sample is not sufficient to allow for Anderson localization of photons in three dimensions, but that an additional magnetic field or additional disorder on the level shifts can induce a phase transition in three dimensions. The role of disorder in atom-light interactions has important consequences for the next generation of high precision atomic clocks and quantum memories. By connecting the mesoscopic physics approach to quantum optics and cooperative scattering, this project will allow better control of cold atoms as building blocks of future quantum technologies. Time-resolved transport experiments will connect super- and subradiant assisted transmission with the extended and localized eigenstates of the system. Having pioneered studies on weak localization and cooperative scattering enables me to diagnostic strong localization of light by cold atoms.

2 490 717 €

Start date: 2019-10-01, End date: 2024-09-30

"During the past twenty years, we have witnessed profound technological changes, summarised under the terms of digital revolution or entering the information age. It is evident that these technological changes will have a deep societal impact, and questions of privacy and security are primordial to ensure the survival of a free and open society. Cryptology is a main building block of any security solution, and at the heart of projects such as electronic identity and health cards, access control, digital content distribution or electronic voting, to mention only a few important applications. During the past decades, public-key cryptology has established itself as a research topic in computer science; tools of theoretical computer science are employed to “prove” the security of cryptographic primitives such as encryption or digital signatures and of more complex protocols. It is often forgotten, however, that all practically relevant public-key cryptosystems are rooted in pure mathematics, in particular, number theory and arithmetic geometry. In fact, the socalled security “proofs” are all conditional to the algorithmic untractability of certain number theoretic problems, such as factorisation of large integers or discrete logarithms in algebraic curves. Unfortunately, there is a large cultural gap between computer scientists using a black-box security reduction to a supposedly hard problem in algorithmic number theory and number theorists, who are often interested in solving small and easy instances of the same problem. The theoretical grounds on which current algorithmic number theory operates are actually rather shaky, and cryptologists are generally unaware of this fact. The central goal of ANTICS is to rebuild algorithmic number theory on the firm grounds of theoretical computer science."

1 453 507 €

Start date: 2012-01-01, End date: 2016-12-31

"In plants, receptor kinases form the largest family of plasma membrane (PM) receptors and they are involved in virtually all aspects of the plant life, including development, immunity and reproduction. In animals, key molecules that orchestrate the recruitment of signaling proteins to membranes are anionic phospholipids (e.g. phosphatidylinositol phosphate or PIPs). Besides, recent reports in animal and yeast cells suggest the existence of PM nanodomains that are independent of cholesterol and lipid phase and rely on anionic phospholipids as well as electrostatic protein/lipid interactions. Strikingly, we know very little on the role of anionic phospholipids in plant signaling. However, our preliminary data suggest that BKI1, an inhibitory protein of the steroid receptor kinase BRI1, interacts with various PIPs in vitro and is likely targeted to the PM by electrostatic interactions with these anionic lipids. These results open the possibility that BRI1, but also other receptor kinases, might be regulated by anionic phospholipids in plants. Here, we propose to analyze the function of anionic phospholipids in BRI1 signaling, using the root epidermis as a model system. First, we will ask what are the lipids that control membrane surface charge in this tissue and recruit BR-signaling component to the PM. Second, we will probe the presence of PIP-enriched nanodomains at the plant PM using super-resolution microscopy techniques and investigate the roles of these domains in BRI1 signaling. Finally, we will analyze the function of the BKI1-related plant-specific family of anionic phospholipid effectors in plant development. In summary, using a transversal approach ranging from in vitro studies to in vivo validation and whole organism physiology, this work will unravel the interplay between anionic phospholipids and receptor signaling in plants."

1 797 840 €

Start date: 2014-02-01, End date: 2019-01-31

The onset of the systematic consumption of marine resources is thought to mark a turning point for the hominin lineage. To date, this onset cannot be traced, since classic isotope markers are not preserved beyond 50 - 100 ky. Aquatic food products are essential in human nutrition as the main source of polyunsaturated fatty acids in hunter-gatherer diets. The exploitation of marine resources is also thought to have reduced human mobility and enhanced social and technological complexification. Systematic aquatic food consumption could well have been a distinctive feature of Homo sapiens species among his fellow hominins, and has been linked to the astonishing leap in human intelligence and conscience. Yet, this hypothesis is challenged by the existence of mollusk and marine mammal bone remains at Neanderthal archeological sites. Recent work demonstrated the sensitivity of Zn isotope composition in bioapatite, the mineral part of bones and teeth, to dietary Zn. By combining classic (C and C/N isotope analyses) and innovative techniques (compound specific C/N and bulk Zn isotope analyses), I will develop a suite of sensitive tracers for shellfish, fish and marine mammal consumption. Shellfish consumption will be investigated by comparing various South American and European prehistoric populations from the Atlantic coast associated to shell-midden and fish-mounds. Marine mammal consumption will be traced using an Inuit population of Arctic Canada and the Wairau Bar population of New Zealand. C/N/Zn isotope compositions of various aquatic products will also be assessed, as well as isotope fractionation during intestinal absorption. I will then use the fully calibrated isotope tools to detect and characterize the onset of marine food exploitation in human history, which will answer the question of its specificity to our species. Neanderthal, early modern humans and possibly other hominin remains from coastal and inland sites will be compared in that purpose.

1 361 991 €

Start date: 2019-03-01, End date: 2024-02-29

Cellular organelles are continuously remodelled by numerous cytosolic proteins that associate transiently with their lipid membrane. Some distort the bilayer, others change its composition, extract lipids or bridge membranes at distance. Previous works from my laboratory have underlined the importance of membrane sensors, i.e. elements within proteins that help to organize membrane-remodelling events by sensing the physical and chemical state of the underlying membrane. A membrane sensor is not necessarily of well-folded domain that interacts with a specific lipid polar head: some intrinsically unfolded motifs harboring deceptively simple sequences can display remarkable membrane adhesive properties. Among these are some amphipathic helices: the ALPS motif with a polar face made mostly by small uncharged polar residues, the Spo20 helix with several histidines in its polar face and, like a mirror image of the ALPS motif, the alpha-synuclein helix with very small hydrophobic residues. Using biochemistry and molecular dynamics, we will compare the membrane binding properties of these sequences (effect of curvature, charge, lipid unsaturation); using bioinformatics we will look for new motifs, using cell biology we will assess the adaptation of these motifs to the physical and chemical features of organelle membranes. Concurrently, we will use reconstitution approaches on artificial membranes to dissect how membrane sensors contribute to the organization of vesicle tethering by golgins and sterol transport by ORP proteins. We surmise that the combination of a molecular ¿switch¿, a small G protein of the Arf family, and of membrane sensors permit to organize these complex reactions in time and in space.

1 997 321 €

Start date: 2011-05-01, End date: 2015-04-30

The project ARTHUS aims at determining the physical origin of Dark Energy: in addition to the energy sources of the standard model of cosmology, effective terms arise through spatially averaging inhomogeneous cosmological models in General Relativity. It has been demonstrated that these additional terms can play the role of Dark Energy on large scales (but they can also mimic Dark Matter on scales of mass accumulations). The underlying rationale is that fluctuations in the Universe generically couple to spatially averaged intrinsic properties of space, such as its averaged scalar curvature, thus changing the global evolution of the effective (spatially averaged) cosmological model. At present, we understand these so- called backreaction effects only qualitatively. The project ARTHUS is directed towards a conclusive quantitative evaluation of these effects by developing generic and non-perturbative relativistic models of structure formation, by statistically measuring the key-variables of the models in observations and in simulation data, and by reinterpreting observational results in light of the new models. It is to be emphasized that there is no doubt about the existence of backreaction effects; the question is whether they are even capable of getting rid of the dark sources (as some models discussed in the literature suggest), or whether their impact is substantially smaller. The project thus addresses an essential issue of current cosmological research: to find pertinent answers concerning the quantitative impact of inhomogeneity effects, a necessary, worldwide recognized step toward high-precision cosmology. If the project objectives are attained, the results will have a far-reaching impact on theoretical and observational cosmology, on the interpretation of astronomical experiments such as Planck and Euclid, as well as on a wide spectrum of particle physics theories and experiments.

2 091 000 €

Start date: 2017-09-01, End date: 2022-08-31

Recent trends in computing have prompted users and organizations to store an increasingly large amount of sensitive data at third party locations in the cloud outside of their direct control. Storing data remotely poses an acute security threat as these data are outside our control and could potentially be accessed by untrusted parties. Indeed, the reality of these threats have been borne out by the Snowden leaks and hundreds of data breaches each year. In order to protect our data, we will need to encrypt it. Functional encryption is a novel paradigm for public-key encryption that enables both fine-grained access control and selective computation on encrypted data, as is necessary to protect big, complex data in the cloud. Functional encryption also enables searches on encrypted travel records and surveillance video as well as medical studies on encrypted medical records in a privacy-preserving manner; we can give out restricted secret keys that reveal only the outcome of specific searches and tests. These mechanisms allow us to maintain public safety without compromising on civil liberties, and to facilitate medical break-throughs without compromising on individual privacy. The goals of the aSCEND project are (i) to design pairing and lattice-based functional encryption that are more efficient and ultimately viable in practice; and (ii) to obtain a richer understanding of expressive functional encryption schemes and to push the boundaries from encrypting data to encrypting software. My long-term vision is the ubiquitous use of functional encryption to secure our data and our computation, just as public-key encryption is widely used today to secure our communication. Realizing this vision requires new advances in the foundations of functional encryption, which is the target of this project.

1 253 893 €

Start date: 2015-06-01, End date: 2020-05-31

A major part of the physical and chemical processes occurring in the atmosphere involves the turbulent transport of tiny particles. Current studies and models use a formulation in terms of mean fields, where the strong variations in the dynamical and statistical properties of the particles are neglected and where the underlying fluctuations of the fluid flow velocity are oversimplified. Devising an accurate understanding of the influence of air turbulence and of the extreme fluctuations that it generates in the dispersed phase remains a challenging issue. This project aims at coordinating and integrating theoretical, numerical, experimental, and observational efforts to develop a new statistical understanding of the role of fluctuations in atmospheric transport processes. The proposed work will cover individual as well as collective behaviors and will provide a systematic and unified description of targeted specific processes involving suspended drops or particles: the dispersion of pollutants from a source, the growth by condensation and coagulation of droplets and ice crystals in clouds, the scavenging, settling and re-suspension of aerosols, and the radiative and climatic effects of particles. The proposed approach is based on the use of tools borrowed from statistical physics and field theory, and from the theory of large deviations and of random dynamical systems in order to design new observables that will be simultaneously tractable analytically in simplified models and of relevance for the quantitative handling of such physical mechanisms. One of the outcomes will be to provide a new framework for improving and refining the methods used in meteorology and atmospheric sciences and to answer the long-standing question of the effects of suspended particles onto climate.

1 200 000 €

Start date: 2009-11-01, End date: 2014-10-31

By enabling the conversion of forces into measurable displacements, mechanical oscillators have always played a central role in experimental physics. Recent developments in the PI group demonstrated the possibility to realize ultrasensitive and vectorial force field sensing by using suspended SiC nanowires and optical readout of their transverse vibrations. Astonishing sensitivities were obtained at room and dilution temperatures, at the Atto- Zepto-newton level, for which the electron-electron interaction becomes detectable at 100µm. The goal of the project is to push forward those ultrasensitive nano-optomechanical force sensors, to realize even more challenging explorations of novel fundamental interactions at the quantum-classical interface. We will develop universal advanced sensing protocols to explore the vectorial structure of fundamental optical, electrostatic or magnetic interactions, and investigate Casimir force fields above nanostructured surfaces, in geometries where it was recently predicted to become repulsive. The second research axis is the one of cavity nano-optomechanics: inserting the ultrasensitive nanowire in a high finesse optical microcavity should enhance the light-nanowire interaction up to the point where a single cavity photon can displace the nanowire by more than its zero point quantum fluctuations. We will investigate this so-called ultrastrong optomechanical coupling regime, and further explore novel regimes in cavity optomechanics, where optical non-linearities at the single photon level become accessible. The last part is dedicated to the exploration of hybrid qubit-mechanical systems, in which nanowire vibrations are magnetically coupled to the spin of a single Nitrogen Vacancy defect in diamond. We will focus on the exploration of spin-dependent forces, aiming at mechanically detecting qubit excitations, opening a novel road towards the generation of non-classical states of motion, and mechanically enhanced quantum sensors.

2 067 905 €

Start date: 2019-09-01, End date: 2024-08-31