French National Centre for Scientific Research
Recent publications
An Ikeda map iterative numerical model completed with an analytical Gaussian analysis and experimental measurements of complex pulse profile and phase noise performance at 10 GHz are proposed. This work aims to study and optimize the chromatic dispersion of a fibered mode-locked laser (MLL) based on a semiconductor optical amplifier (SOA) as part of a coupled optoelectronic oscillator (COEO). We will demonstrate that a close to zero anomalous dispersion regime is preferred as it allows the generation of optical picosecond pulses with minimum full width at half maximum (FWHM) and maximizes the absolute value of chirp and peak power. This guarantees the generation of narrow and diffraction-limited optical pulses after the chromatic dispersion compensating stage prior photodetection in order to lower the phase noise of the microwave signal generated at 10 GHz but also for high-order microwave harmonics synthesis.
Reconfigurable intelligent surfaces (RISs) are expected to play a crucial role in reaching the key performance indicators (KPIs) for future 6G networks. Their competitive edge over conventional technologies lies in their ability to control the wireless environment propagation properties at will, thus revolutionizing the traditional communication paradigm that perceives the communication channel as an uncontrollable black box. As RISs transition from research to market, practical deployment issues arise. Major roadblocks for commercially viable RISs are i) the need for a fast and complex control channel to adapt to the ever-changing wireless channel conditions, and ii) an extensive grid to supply power to each deployed RIS. In this paper, we question the established RIS practices and propose a novel RIS design combining self-configuration and energy self-sufficiency capabilities. We analyze the feasibility of devising fully-autonomous RISs that can be easily and seamlessly installed throughout the environment, following the new internet-of-surfaces (IoS) paradigm, requiring modifications neither to the deployed mobile network nor to the power distribution system. In particular, we introduce ARES, an Autonomous RIS with Energy harvesting and Self-configuration solution. ARES achieves outstanding communication performance while demonstrating the feasibility of energy harvesting (EH) for RISs power supply in future deployments.
The IEEE 1687 standard, commonly called ITAG, introduced several innovations. While the hardware-related ones, most notably mux-enabled dynamic topologies, are clearly successful and are widely adopted, several pans of the standard are still unsupported by the EDA vendors and are little known to the general public. In particular, the Procedural Description Language (PDL) theoretically allows for interactive routines whose outputs and control flow can be modified by the data retrieved from the System Under Test. However, the traditional Test Flow and Execution backend are not able to really support such features. In this paper, we present an in-depth analysis of these limitations and propose a fully-functional solution able to support true interactive behavior, whose features are demonstrated through a Proof-of-Concept.
Physical Unclonable Functions (PUFs) are integral for generating unique signatures, secret keys, and device identification, leveraging inherent manufacturing process variability. Mathematically defined as functions linking inputs (challenges) to outputs (responses), PUFs exhibit random properties. Key properties for high-quality PUFs include intra-device entropy (random distribution of responses within the same circuit), inter-device entropy (random distribution across different circuits for identical challenges), and reliability (response consistency for identical challenges and the same circuit). Inter-device entropy and reliability may be influenced by design discrepancies, systematic variability, noise, and aging. This paper addresses the correlation between entropy and reliability, providing evidence from an extensive set of circuits featuring diverse Ring Oscillators supplied by Infineon.
The increasing integration of renewable energies, while beneficial for environmental and economic sustainability through decarbonization, poses challenges to frequency stability due to the intermittent nature of renewable power supply. To facilitate smoother integration into the main grid, this study proposes a resilient distributed load frequency control (RDLFC) strategy with a hierarchical structure. At the lower level, wind energy integration is managed using a model predictive control framework enhanced by an improved event-triggered scheme, which can effectively trigger key feedback signals at critical points and tolerates imperfect event modeling and generator dysfunctions. Plug-in electric vehicles are also utilized for fast frequency regulation. At the higher level, the linearized model is improved with an uncertain parameter matrix to account for variations in steady-state operating points due to renewable integration. A robust performance index is incorporated to derive stability conditions, even in the presence of temporary faults in phasor measurement units (PMUs). Validation results confirm the effectiveness of the proposed RDLFC strategy in handling temporary PMU faults.
Photoactivatable fluorescent probes are valuable tools in bioimaging for tracking cells down to single molecules and for single molecule localization microscopy. For the latter application, green emitting dyes are in demand. We herein developed an efficient green‐emitting photoactivatable furanyl‐BODIPY (PFB) and we established a new mechanism of photoactivation called Directed Photooxidation Induced Activation (DPIA) where the furan is photo‐oxidized in a directed manner by the singlet oxygen produced by the probe. The efficient photoconverter (93‐fold fluorescence enhancement at 510 nm, 49 % yield conversion) is functionalizable and allowed targeting of several subcellular structures and organelles, which were photoactivated in live cells. Finally, we demonstrated the potential of PFB in super‐resolution imaging by performing PhotoActivated Localization Microscopy (PALM) in live cells.
Recently, the control of dynamic chirality has emerged as a powerful strategy to design chiral functional materials. In this context, we describe herein a molecular design in which a tethered configurationally stable binaphthyl chiral unit efficiently controls the dynamic chirality of donor‐acceptor fluorophores, involving diverse indolocarbazoles as electron donors and terephthalonitrile as an electron acceptor. The high conformational discrimination in such a molecular system suggested by density functional theory calculations is experimentally probed using electronic and vibrational circular dichroism and confirmed by the crystallization of these chiral molecules in gel and their single crystal X‐ray diffraction analysis. This work also highlights the positive effect of the configurationally stable chiral unit on the magnitude of the dissymmetry factors of the active dynamically chiral fluorophores, both in ground and excited states, through chiral perturbation.
Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents suitable for this modality remains very scarce. In this work, we have synthesized and fully characterized, including theoretical calculations, a series of dimeric LnIII/GaIII metallacrowns bearing RuII polypyridyl complexes, LnRu‐3 (Ln=YIII, YbIII, NdIII, ErIII). Relaxed structures of YRu‐3 in the ground and the excited electronic states have been calculated using dispersion‐corrected density functional theory methods. Detailed photophysical studies of LnRu‐3 have demonstrated that characteristic emission signals of YbIII, NdIII and ErIII in the NIR‐II range can be sensitized upon excitation in the visible range through RuII‐centered metal‐to‐ligand charge transfer (MLCT) states. We have also showed that these NIR‐II signals are unambiguously detected in an imaging experiment using capillaries and biological tissue‐mimicking phantoms. This work opens unprecedented perspectives for NIR‐II multiplex imaging using LnIII‐based molecular compounds.
The acoustic repertoires of long-finned pilot whales (Globicephala melas) in the Mediterranean Sea are poorly understood. This study aims to create a catalogue of calls, analyse acoustic parameters, and propose a classification tree for future research. An acoustic database was compiled using recordings from the Alboran Sea, Gulf of Lion and Ligurian Sea (Western Mediterranean Basin) between 2008 and 2022, totalling 640 calls. Using a deep neural network, the calls were clustered based on frequency contour similarities, leading to the identification of 40 distinct call types defining the local population’s vocal repertoire. These categories encompass pulsed calls with varied complexities, from simplistic to highly intricate structures comprising multiple elements and segments. This study marks the initial documentation of the vocal catalogue of long-finned pilot whales in the Mediterranean Sea. Subsequent research should delve deeper into this multifaceted communication system and explore its potential linkages with social structures.
Light dragging phenomena in accelerated media have classically been modelled neglecting the effect of inertia on the dielectric response of the media. Here, we show that the inertial corrections due to a rotating motion can have a profound impact on light-dragging manifestations, leading notably to birefringence in media that are isotropic at rest. By applying these findings to a rotating unmagnetized plasma, we further reveal how inertia plays, in this case, a dominant role, offering unique opportunities to expose these new effects. Inertia is notably demonstrated to be the source of non-zero drag and enhanced polarization drag, pointing to fundamental differences between linear and angular momentum coupling. In taking advantage of the singular properties of plasmas, this work more generally underlines how rest-frame properties are affected by an accelerated motion, and how these modifications can carry over to wave dynamics.
Aim The Mediterranean Sea is one of the most anthropized seas in the world but also a marine biodiversity hotspot with many fish species under threat. The main goal of the study is to test whether on the heavily fished and anthropized Mediterranean coast, the less impacted Corsica and Balearic Islands, can be considered as refugia for threatened and elasmobranch fishes independently of protection by marine reserves. Location The French Mediterranean coast and three north‐western Mediterranean islands: Corsica and also Mallorca and Minorca from the Balearic archipelago. Methods We performed 187 fish surveys using environmental DNA metabarcoding on three islands and 109 along the continental coast. Of the 78 surveys on islands 22 correspond to no‐take marine reserves and of the 109 continental surveys 26 were carried out within reserves. After eDNA filtration, extraction, amplification, and sequencing we estimated the number of fish species but also the number commercial, threatened and elasmobranch fish species on each sample. We then performed an ANOVA by permutation to test the effect of insularity and protection on these four biodiversity metrics. We also modelled these four biodiversity metrics as a function of protection and human pressure but also environmental, habitat and sampling conditions. We also built species accumulation curves to obtain asymptotes representing the potential regional pools for each species category on both island and continental coasts. Results We obtained a total of 175,982,610 reads over the 187 eDNA samples that were assigned to 153 fish species including 17 elasmobranch species among which 7 were only detected on islands. We observed a higher total fish richness on continental than island surveys regardless of protection but a higher threatened and elasmobranch fish richness on the island than on continental surveys. We obtained a significant, negative and predominant human gravity impact on the diversity of elasmobranch species. The modelled asymptote reached 148 teleostean fish species on islands and 196 on the continental coastline with a very similar rate of diversity increase with sampling effort but the shape of the species accumulation curves differed markedly for elasmobranchs with a stronger increase in diversity with sampling effort on islands. Main Conclusions Our findings highlight that Mediterranean islands can be refugia for sharks and rays but also threatened fishes in this overexploited region. Our results also suggest that reducing or banning trawling activities may play a key role for conserving vulnerable fishes, beyond the benefits of no‐take marine reserves, which appear limited on these large home‐range species.
Time‐gated or time‐resolved FRET (TR‐FRET) assays are important tools in biosensing, bioimaging, drug screening, and molecular diagnostics. Efficient TR‐FRET assays require stable lanthanide complexes with high absorption cross sections, high quantum yields, and long photoluminescence lifetimes. Owing to their challenging synthesis, such complexes are relatively rare and new components are of potential interest when developing TR‐FRET probes. Here, we evaluate the recently developed Tb complex CoraFluor‐1 concerning its analytical performance in terbium‐to‐quantum dot FRET and terbium‐to‐gold nanoparticle NSET assays using the prototypical biological recognition system of streptavidin and biotin. Biological binding was quantifiable at sub‐picomolar concentrations in small sample volumes, with broad applicability demonstrated across three commercial fluorescence plate readers used for time‐resolved, spectrally‐resolved, and clinical bioanalysis. Overall, CoraFluor‐1 provided excellent analytical performance as both FRET and NSET donor, validating its potential for developing new TR‐FRET probes for biosensing and bioimaging.
Chiral 1D coordination compounds formed by association of either of the enantiomers of [ML(MeOH)Cl]Cl (with M=MnII or FeII; L stands for either R or S enantiomer of a pentadentate macrocycle) and NBu4[FeIII(bpb)(CN)2], namely: 1D‐[{FeIII(bpb)(CN)2}{MII(LR)}](PF6) and 1D‐[{FeIII(bpb)(CN)2}{MII(LS)}](PF6) with M=Mn (2R, 2S) and Fe (3R, 3S). The bis(triphenylphosphine)iminium salt of the metallo‐ligand, PNP[FeIII(bpb)(CN)2]⋅2H2O, 1 b, is also described. Their preparations, crystal structures, optical and magnetic properties are reported. Mössbauer spectroscopy confirmed the oxidation state in the [FeII−FeIII] chain, for which AC susceptibility suggests SCM behavior, but for very low T.
This paper explores the microfabrication process of plasma reactors, from the production of micro-reactors to the addition of through silicon vias (TSV) using proprietary etching techniques and on site cleanroom facilities. The investigation focuses on both newly fabricated closed and open-cavity micro-hollow cathode discharge (MHCD) reactors, with particular emphasis on electrical and optical diagnostics to characterize their plasma properties. All experiments, including those on closed-cavity reactors, were specifically conducted for this study under identical conditions to ensure a rigorous comparison between reactor types. When electrical diagnostics were carried out in helium at various pressures, interesting phenomena such as the evolution of voltage breakdown were observed. These diagnostics also provided new insights into the impact of surface electrode and overall geometry properties and pressure on reactor performance. Additional investigation into instability mechanisms revealed self-pulsing oscillations, with different reactor types having different oscillation amplitudes for similar operating conditions. Optical emission spectroscopy (OES) emerged as a strong tool for spatial plasma analysis, revealing consistent gas temperature distributions across reactor diameters. The Inglis-Teller series provided an estimate of the upper limit of electron density, while the Stark broadening analysis of Hα offered valuable insights into electron density variations, particularly in the self-pulsing regime.
Protected areas (PAs) have expanded rapidly in recent decades to help mitigate the ongoing biodiversity crisis but are under increasing human pressures that jeopardize their conservation effectiveness. Tourism in PAs may galvanize efforts towards biodiversity conservation, but it can also be a major source of threats, leading to multiple adverse social and ecological impacts. Considering the recent Kunming‐Montreal Global Biodiversity Framework, which aims to protect at least 30% of terrestrial ecosystems by 2030, understanding and assessing how and which PAs shape the spatial distribution of tourism is of great importance to biodiversity management and policy. In this study, we used a geospatial data set that describes the location and capacity of tourism accommodation in 81,185 local administrative units (LAUs) covering over 28 countries across rural Europe. After estimating the number of nights spent per LAU, we modelled the influence of PAs on the distribution of tourism throughout Europe while controlling for other social, economic and environmental covariates, but also for spatial autocorrelation. We reveal a positive link between highly protected PAs and the number of nights spent by tourists in LAUs. The attractiveness of these PAs for tourists may pose a conservation paradox, that is, highly protected PAs, which aim to safeguard nature tend to attract a disproportionate number of tourists, which may lead to nature degradation. Read the free Plain Language Summary for this article on the Journal blog.
Phylodynamics is central to understanding infectious disease dynamics through the integration of genomic and epidemiological data. Despite advancements, including the application of deep learning to overcome computational limitations, significant challenges persist due to data inadequacies and statistical unidentifiability of key parameters. These issues are particularly pronounced in poorly resolved phylogenies, commonly observed in outbreaks such as SARS-CoV-2. In this study, we conducted a thorough evaluation of PhyloDeep, a deep learning inference tool for phylodynamics, assessing its performance on poorly resolved phylogenies. Our findings reveal the limited predictive accuracy of PhyloDeep (and other state-of-the-art approaches) in these scenarios. However, models trained on poorly resolved, realistically simulated trees demonstrate improved predictive power, despite not being infallible, especially in scenarios with superspreading dynamics, whose parameters are challenging to capture accurately. Notably, we observe markedly improved performance through the integration of minimal contact tracing data, which refines poorly resolved trees. Applying this approach to a sample of SARS-CoV-2 sequences partially matched to contact tracing from Hong Kong yields informative estimates of superspreading potential, extending beyond the scope of contact tracing data alone. Our findings demonstrate the potential for enhancing phylodynamic analysis through complementary data integration, ultimately increasing the precision of epidemiological predictions crucial for public health decision making and outbreak control.
What challenges must be overcome to achieve parity democracy in twenty-first century Europe? In view of the political participation crisis, most visible in the disaffection of citizens with elections and their mistrust of elected representatives, coupled with the rise of populism, Europe has a role to play in reviving the political debate, particularly in the defence and enforcement of fundamental rights. To address these issues, we analyse how Europe can participate in the advent of a more egalitarian democracy, in keeping with its role in redefining democracy through the lens of parity. We then examine the current challenges that need to be overcome to address this issue from two angles: the connection between descriptive and substantive representation, and the overlap between inequalities and demands from an intersectional perspective.
We establish some algebraic properties of the group Diff(Cn,0)Diff(Cn,0)\textrm{Diff}(\mathbb {C}^n,0) of germs of analytic diffeomorphisms of CnCn\mathbb {C}^n at 0, and its formal completion Diff^(Cn,0)Diff^(Cn,0)\widehat{\textrm{Diff}}(\mathbb {C}^n,0). For instance we describe the commutator of Diff(Cn,0)Diff(Cn,0)\textrm{Diff}(\mathbb {C}^n,0), but also prove that any finitely generated subgroup of Diff(Cn,0)Diff(Cn,0)\textrm{Diff}(\mathbb {C}^n,0) is residually finite; we thus obtain some constraints of groups that embed into Diff(Cn,0)Diff(Cn,0)\textrm{Diff}(\mathbb {C}^n,0). We show that Diff^(Cn,0)Diff^(Cn,0)\widehat{\textrm{Diff}}(\mathbb {C}^n,0) is an Hopfian group, and that Diff^(Cn,0)Diff^(Cn,0)\widehat{\textrm{Diff}}(\mathbb {C}^n,0) and Diff(Cn,0)Diff(Cn,0)\textrm{Diff}(\mathbb {C}^n,0) are not co-Hopfian. We end by the description of the automorphism groups of Diff^(C,0)Diff^(C,0)\widehat{\textrm{Diff}}(\mathbb {C},0), and Diff(C,0)Diff(C,0)\textrm{Diff}(\mathbb {C},0).
Stratospheric transit time distributions (age‐of‐air spectra) are estimated using time series of satellite water vapor (H2O) measurements from the Microwave Limb Sounder over 2004 to 2021 assuming stationary transport. Latitude‐altitude dependent spectra are derived from correlations of interannual H2O anomalies with respect to the tropical tropopause source region, fitted with an inverse Gaussian distribution function. The reconstructions accurately capture interannual H2O variability in the “tropical pipe” and near‐global lower stratosphere, regions of relatively fast transport (∼1–2 years) in the Brewer‐Dobson circulation. The calculations provide novel observational estimates of the corresponding “short transit‐time” part of the age spectrum in these regions, including the mode. However, the H2O results do not constrain the longer transit‐time “tail” of the age spectra, and the mean age of air and spectral widths are systematically underestimated compared to other data. We compare observational results with parallel calculations applied to the WACCM chemistry‐climate model and the CLaMS chemistry‐transport model, and additionally evaluate the method in CLaMS by comparing with spectra from idealized pulse tracers. Because the age spectra accurately capture H2O interannual variations originating from the tropical tropopause, they can be used to identify “other” sources of variability in the lower stratosphere, and we use these calculations to quantify H2O anomalies in the Southern Hemisphere linked to the Australian New Years fires in early 2020 and the Hunga volcanic eruption in 2022.
Background Acinetobacter baumannii is a gram-negative, opportunistic pathogen, that is responsible for a wide variety of infections and is a significant cause of hospital-acquired infections. A. baumannii is listed by the World Health Organization (WHO) as a critical priority pathogen because of its high level of antibiotic resistance and the urgent need for alternative treatment solutions. To address this challenge, bacteriophages have been used to combat bacterial infections for more than a century, and phage research has regained interest in recent years due to antimicrobial resistance (AMR). However, although the vast majority of deaths from the AMR crisis will occur in developing countries in Africa and Asia, few phages’ studies have been conducted in these regions. In this study, we present a comprehensive characterization of the bacteriophages vAbBal23 and vAbAbd25, actives against extremely drug-resistant (XDR) A. baumannii. Methods Phages were isolated from environmental wastewaters in Dakar, Senegal. The host-range, thermal and pH stabilities, infection kinetics, one step growth assay, antibiofilm activity assay, sequencing, and genomic analysis, were performed to characterize the isolated phages. Results Comparative genomic and phylogenetic analyses revealed that vAbBal23 and vAbAbd25 belong to the Caudoviricetes class, Autographiviridae family and Friunavirus genus. Both phages demonstrated activity against strains with capsular type KL230. They were stable over a wide pH range (pH 3 to 9) and at temperatures ranging from 25 °C to 40 °C. Additionally, the phages exhibited notable activity against both planktonic and biofilm cells of targeted extremely drug resistant A. baumannii. The results presented here indicate the lytic nature of vAbBal23 and vAbAbd25. This is further supported by the absence of genes encoding toxins, resistance genes and bacterial virulence factors, highlighting their potential for future phage applications. Conclusion Phages vAbBal23 and vAbAbd25 are promising biological agents that can infect A. baumannii, making them suitable candidates for use in phage therapies.
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8,638 members
Kevin Cassou
  • Laboratoire de l'accélérateur linéaire
Jérôme Majimel
  • Institut de Chimie (INC)
Virgile Adam
  • Institut de Biologie Structurale (IBS)
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Alain Dollet