Portail HAL de l’Université Claude Bernard Lyon
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Topological data analysis of human vowels: Persistent homologies across representation spaces
No full textInternational audienceTopological Data Analysis (TDA) has been successfully used for various tasks in signal/image processing, from visualization to supervised/unsupervised classification. Often, topological characteristics are obtained from persistent homology theory. The standard TDA pipeline starts from the raw signal data or a representation of it. Then, it consists in building a multiscale topological structure on the top of the data using a pre-specified filtration, and finally to compute the topological signature to be further exploited. The commonly used topological signature is a persistent diagram (or transformations of it). Current research discusses the consequences of the many ways to exploit topological signatures, much less often the choice of the filtration, but to the best of our knowledge, the choice of the representation of a signal has not been the subject of any study yet. This paper attempts to provide some answers on the latter problem. To this end, we collected real audio data and built a comparative study to assess the quality of the discriminant information of the topological signatures extracted from three different representation spaces. Each audio signal is represented as i) an embedding of observed data in a higher dimensional space using Taken's representation, ii) a spectrogram viewed as a surface in a 3D ambient space, iii) the set of spectrogram's zeroes. From vowel audio recordings, we use topological signature for three prediction problems: speaker gender, vowel type, and individual. We show that topologically-augmented random forest improves the Out-of-Bag Error (OOB) over solely based Mel-Frequency Cepstral Coefficients (MFCC) for the last two problems. Our results also suggest that the topological information extracted from different signal representations is complementary, and that spectrogram's zeros offers the best improvement for gender prediction
The alpha rhythm: from physiology to behaviour
No full textInternational audienceThe alpha rhythm, first identified by Hans Berger 100 years ago, is the dominant non-invasive electrophysiological signature of the healthy human brain in the awake state. For decades, it was believed that the alpha rhythm reflected rest or idling; however, this perspective changed in the 2000s when researchers found that alpha oscillations increase with cognitive demands. This discovery led to a paradigm shift, demonstrating that alpha oscillations reflect the functional inhibition of brain regions that are not needed for a specific task, thereby directing information to task-specific areas. We have reviewed the physiological mechanisms involved in generating alpha oscillations, which has informed computational models explaining how these oscillations emerge within physiologically realistic networks. At the behavioural level, alpha oscillations are strongly modulated across nearly all cognitive paradigms tested in humans, reflecting the allocation of computational resources within the active brain network. Research in individuals with attention-related issues has highlighted their impaired ability to modulate alpha oscillations, which is associated with performance deficits. Therefore, further exploration of alpha oscillations has the potential to uncover causal mechanisms underlying attention problems, such as those related to ADHD and ageing. Lastly, advancements in technology are opening new avenues for characterising alpha oscillations in ecologically valid settings and across the lifespan. This progress sets the stage for exploring the role of alpha oscillations in cognitive development and their functioning in natural environments
Effects of deep brain stimulation on non motor fluctuations in Parkinson’s disease (assessed with the NMF severity scale)
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Metabolic acidosis causes a Fanconi-like syndrome with intracellular trafficking defects and proximal tubule dysfunction
No full textInternational audiencePatients suffering from distal renal tubular acidosis (dRTA) are sometimes diagnosed with proximal tubule dysfunction with leaks of phosphate, uric acid, amino acids, and low–molecular weight proteins, a condition also known as Fanconi-like syndrome. The underlying molecular basis is largely elusive. We previously reported on ATPase H + transporting V0 subunit a4 ( Atp6v0a4 ) knockout (KO) mice, which exhibit severe metabolic acidosis in combination with proximal tubule dysfunction as evidenced by phosphaturia and proteinuria. Here, we show that ras analog in brain 7 (Rab7), a key regulator of endolysosomal trafficking and lysosomal biogenesis, was diminished, and the number of abnormal lysosomal-associated membrane protein 1 (Lamp1)–positive vesicles labeled for increased sodium tolerance 1 (Ist1) was increased in proximal tubules of Atp6v0a4 KO mice. This was accompanied by the accumulation of autophagosomes, autolysosomes, and autophagic substrates. Correction of metabolic acidosis with bicarbonate therapy resolved proximal tubule dysfunction and trafficking defects in Atp6v0a4 KO mice. After 28 days of acid challenge, wild-type mice showed comparable trafficking defects to Rab7 down-regulation and an increase in Ist1-labeled Lamp1-positive vesicles and proximal tubule damage. Acidosis-induced decreases in RAB7-labeled particles and increased numbers of IST1-labeled LAMP1-positive particles also occurred in proximal tubule correlates of human kidney organoids derived from the widely used induced pluripotent stem cell line KOLF2.1J. Together, our data provide insight into why patients suffering from severe dRTA can develop a Fanconi-like syndrome, which may contribute to the progression of chronic kidney failure
Approches psychothérapeutiques du jeu d'argent pathologique
No full textInternational audienceLa place du jeu d'argent pathologique (JAP) est aujourd'hui établie dans le champ des troubles addictifs. Cependant, le repérage précoce de ce trouble est encore limité. Les prises en charge proposées dans cette addiction rejoignent celles qui sont généralement utilisées dans les troubles de l'usage de substance (TUS), mais des aménagements sont nécessaires afin de correspondre aux caractéristiques propres aux addictions comportementales. Dans cette revue narrative, les principales approches psychothérapeutiques utilisées dans le traitement des addictions sont décrites et analysées en fonction de leur adaptation aux spécificités du JAP. L'entretien motivationnel (EM), les thérapies comportementales et cognitives (TCC), et les approches groupales sont fréquentes dans le traitement des addictions, et leur application au JAP suppose des aménagements particuliers. La fréquence de la comorbidité entre JAP et trouble du stress post traumatique (TSPT) est importante. Cette comorbidité peut avoir un impact sur la sévérité du trouble et le maintien du comportement. Ainsi, il peut être pertinent de proposer un traitement capable de prendre en charge cette association. L'Eye Movement Desensitization et Reprocessing (EMDR) permet une prise en charge prometteuse de cette comorbidité. Des travaux supplémentaires pourraient permettre de mieux cibler les interventions proposées en fonction des différents profils de joueurs pathologiques.</div
Elementary blocks of Loop Quantum Gravity
No full textInternational audienceWe embark on the vast program of integrating the dynamics of Loop Quantum Gravity (LQG). Adopting the strategy of decomposing spin network states into small blocks of (quantum) geometry which can later be glued back together, we focus on the more modest objective of studying the Hamiltonian dynamics on the {\it candy graph}, that is two nodes linked together by an arbitrary number of edges and also having open edges. This elementary setting allows both for curvature to develop around the bulk loops and both non-trivial boundary data and dynamics on the open edges. We study this system at the classical level and leave the detailed of its quantum regime for future investigation. Working on a single loop with two external legs, we show how the LQG Hamiltonian ansatz reduces to a pair of non-linear differential equations, similar to the cubic Schrödinger equation, on the areas carried by the bulk links. We provide analytical solutions to this evolution equation, identifying oscillatory modes (bounded modes) and divergent modes (similar to bouncing cosmological trajectories). This provides an explicit template for future investigations of LQG dynamics on more sophisticated spin network architecture built as arrays of candy graphs
Amélioration du diagnostic moléculaire de l’insuffisance ovarienne prématurée (IOP) grâce à un modèle poisson médaka
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Euclid: Early Release Observations. A combined strong and weak lensing solution for Abell 2390 beyond its virial radius
No full textInternational audienceEuclid is presently mapping the distribution of matter in the Universe in detail via the weak lensing (WL) signature of billions of distant galaxies. The WL signal is most prominent around galaxy clusters, and can extend up to distances well beyond their virial radius, thus constraining their total mass. Near the centre of clusters, where contamination by member galaxies is an issue, the WL data can be complemented with strong lensing (SL) data which can diminish the uncertainty due to the mass-sheet degeneracy and provide high-resolution information about the distribution of matter in the centre of clusters. Here we present a joint SL and WL analysis of the Euclid Early Release Observations of the cluster Abell 2390 at z=0.228. Thanks to Euclid's wide field of view of 0.5 deg^2, combined with its angular resolution in the visible band of 0."13 and sampling of 0."1 per pixel, we constrain the density profile in a wide range of radii, 30 kpc < r < 2000 kpc, from the inner region near the brightest cluster galaxy to beyond the virial radius of the cluster. We find consistency with earlier X-ray results based on assumptions of hydrostatic equilibrium, thus indirectly confirming the nearly relaxed state of this cluster. We also find consistency with previous results based on weak lensing data and ground-based observations of this cluster. From the combined SL+WL profile, we derive the values of the viral mass M_{200} = (1.48 \pm 0.29)\times10^{15}\, \Msun, and virial radius ), with error bars representing one standard deviation. The profile is well described by an NFW model with concentration c=6.5 and a small-scale radius of 230 kpc in the 30 kpc < r < 2000 kpc range that is best constrained by SL and WL data. Abell 2390 is the first of many examples where Euclid data will play a crucial role in providing masses for clusters
Black Hole Spectroscopy and Tests of General Relativity with GW250114
No full textInternational audienceThe binary black hole signal GW250114, the loudest gravitational wave detected to date, offers a unique opportunity to test Einstein’s general relativity (GR) in the high-velocity, strong-gravity regime and probe whether the remnant conforms to the Kerr metric. Upon perturbation, black holes emit a spectrum of damped sinusoids with specific, complex frequencies. Our analysis of the postmerger signal shows that at least two quasinormal modes are required to explain the data, with the most damped remaining statistically significant for about one cycle. We probe the remnant’s Kerr nature by constraining the spectroscopic pattern of the dominant quadrupolar (ℓ=m=2) mode and its first overtone to match the Kerr prediction to tens of percent at multiple postpeak times. The measured mode amplitudes and phases agree with a numerical-relativity simulation having parameters close to GW250114. By fitting a parametrized waveform that incorporates the full inspiral-merger-ringdown sequence, we constrain the fundamental (ℓ=m=4) mode to tens of percent and bound the quadrupolar frequency to within a few percent of the GR prediction. We perform a suite of tests—spanning inspiral, merger, and ringdown—finding constraints that are comparable to, and in some cases 2–3 times more stringent than those obtained by combining dozens of events in the fourth Gravitational-Wave Transient Catalog. These results constitute the most stringent single-event verification of GR and the Kerr nature of black holes to date, and outline the power of black-hole spectroscopy for future gravitational-wave observations
Intraoperative Assessment of Kinematics Using Robotic-Assisted Total Knee Arthroplasty Is Reliable: A Cadaver-Based Study
No full textInternational audienceAbstract Computed tomography–based robotic-arm-assisted total knee arthroplasty (RATKA) enables three-dimensional surgical planning and intraoperative adjustment of implant positioning based on ligament laxity. Stability and kinematic assessments may offer enhanced insight into multiplanar knee laxity, but their reproducibility remains underexplored. This study evaluated the reliability of intraoperative knee kinematic (dynamic), sagittal and transverse stability assessments in a cadaver setting under different support conditions. Cruciate-retaining RATKA was performed on five fresh-frozen cadaver knees by three experienced surgeons. Medial and lateral anteroposterior translation (MAP, LAP) and internal–external rotation (IE) were measured at 10, 45, and 90 degrees of flexion before and after component implantation. Dynamic assessments across the full range of motion were used to calculate the average medial contact position (AMCP) and medial pivot ratio (MPR). Inter- and intra-rater reliability were determined using intraclass correlation coefficients (ICC: poor < 0.4, good 0.4 to 0.74, and excellent ≥ 0.75). Analyses compared a leg-holder-only condition with all surgeons, including manual support. Intra- and inter-rater reliability across all surgeons was generally good to excellent. For intact knees, reliability ranged from ICC 0.52 to 0.84 for MAP, 0.44 to 0.57 for LAP, and 0.48 to 0.62 for IE. With components, reliability remained good to excellent for MAP, LAP, and IE (ICC 0.47 to 0.80). Dynamic AMCP assessments demonstrated excellent inter-rater reliability (ICC 0.84 to 0.93), while MPR showed good reliability (ICC 0.57). The leg holder reduced variance for MAP/LAP and IE, maintaining error within two mm or 5 degrees, respectively. Intra-rater reliability was consistently excellent across nearly all measures (ICC 0.69 to 0.99). Intraoperative stability and kinematic assessments during RATKA are reproducible, particularly for AMCP. The leg holder generally improved consistently across observers and reduced variance. These findings support the reliability of robotic-assisted intraoperative stability and kinematic measures for evaluating knee function and guiding surgical planning