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Neuroimaging and Pathology Biomarkers in Parkinson's Disease and Parkinsonism
No full textInternational audienceThe "Neuroimaging and Pathology Biomarkers in Parkinson's Disease" course held on 12-13 September 2025 in Milan, Italy, convened an international faculty to review state-ofthe-art biomarkers spanning neurotransmitter dysfunction, protein pathology and clinical translation. Here, we synthesize the four themed sessions and highlights convergent messages for diagnosis, stratification and trial design. The first session focused on neuroimaging markers of neurotransmitter dysfunction, highlighting how positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI) provided complementary insights into dopaminergic, noradrenergic, cholinergic and serotonergic dysfunction. The second session addressed in vivo imaging of protein pathology, presenting recent advances in PET ligands targeting αsynuclein, progress in four-repeat tau imaging for progressive supranuclear palsy and corticobasal syndromes, and the prognostic relevance of amyloid imaging in the context of mixed pathologies. Imaging of neuroinflammation captures inflammatory processes in vivo and helps study pathophysiological effects. The third session bridged pathology and disease mechanisms, covering the biology of α-synuclein and emerging therapeutic strategies, the clinical potential of seed amplification assays and skin biopsy, the impact of co-pathologies on disease expression, and the "brain-first" versus "body-first" model of pathological spread. Finally, the fourth session addressed disease progression and clinical translation, focusing on imaging predictors of phenoconversion from prodromal to clinically overt stages of synucleinopathies, concepts of neural reserve and compensation, imaging correlates of cognitive impairment, and MRI approaches for atypical parkinsonism. Biomarker-informed pharmacological, infusion-based, and surgical strategies, including network-guided and adaptive deep brain stimulation, were discussed as examples of how multimodal biomarkers may inform personalized management. Across all sessions, the need for harmonization, longitudinal validation, and pathology-confirmed outcome mea
Salvage of Failed Patellofemoral Arthroplasty Due to Instability: Combined Medial Patellofemoral Ligament Reconstruction, Tibial Tubercle Osteotomy, and Vastus Medialis Obliquus Advancement - Case Report and Algorithm-Based
No full textInternational audienceIntroduction/Objectives: Patellofemoral arthroplasty (PFA) is a joint-sparing alternative to total knee arthroplasty (TKA) for isolated patellofemoral osteoarthritis, offering symptom relief while preserving tibiofemoral compartments and bone stock compared with TKA, particularly in younger and active patients. However, persistent anterior knee pain and patellar instability remain leading causes of early failure, even when prosthetic components are stable and tibiofemoral degeneration is absent. This study aimed to describe a combined, non-prosthetic surgical strategy for symptomatic PFA failure due to patellar instability and to propose an algorithm-based framework for clinical decision-making. Methods: A 54-year-old woman presented with chronic anterior knee pain and recurrent instability four years after isolated PFA. Imaging confirmed stable and well-aligned prosthetic components with preserved tibiofemoral compartments but consistent lateral patellar subluxation. The patient was treated using a joint-preserving approach combining medial patellofemoral ligament (MPFL) reconstruction with hamstring autograft, anteromedial tibial tubercle osteotomy, and vastus medialis obliquus (VMO) advancement. Clinical outcomes were assessed with the Kujala and International Knee Documentation Committee (IKDC) scores at six weeks and three months. Results:At three months, the Kujala score improved from 54 to 78, and the IKDC subjective score increased from 38 to 69. The patient reported significant pain reduction, restoration of patellar stability, and functional recovery. No recurrent instability, surgical complications, or implant-related problems were observed. Radiographs confirmed correct alignment and congruent prosthetic components.Conclusion:A combined approach addressing soft-tissue, bony, and dynamic stabilizers may provide an effective, joint-preserving alternative to total knee arthroplasty in selected patients with symptomatic PFA failure caused by instability. The algorithm presented may assist in surgical decision-making and optimize patient outcomes
An intense peak of paraglacial dismantlement of mountain slopes: Insights from dating and volume quantification of rock-slope failure deposits in the Icelandic Westfjords (Dýrafjörður and Önundarfjörður)
No full textInternational audienceParaglacial rock slope failures (RSFs) are prominent processes of landscape evolution in deglaciated terrains, such as the Westfjords of Iceland. This study aims to provide chronological and volumetric data on RSF deposits in the Dýrafjörður and Önundarfjörður fjords, in order to document the magnitude, duration, and geomorphic impact of the intense peak of Early and Middle Holocene paraglacial denudation. By refining the timing of a paraglacial signal, this work contributes to a better understanding of sedimentary production and landscape evolution during the Holocene.A total of 17 RSFs was studied, described and mapped using the Schmidt-hammer exposure-age dating method, calibrated with radiocarbon dating. Surficial block morphometry and volumetric estimates of RSF deposits were derived from field measurements, orthophotography, and high-resolution digital elevation models.RSF ages are concentrated in the Early to Middle Holocene. The vast majority of this activity occurred between 12 and 6 cal. ka BP. During this 6000-year interval, ~83 million m3 of debris were deposited, which accounts for approximately 90% of the total volume (~92.5 M m3) from all 17 RSF sites. This indicates a primary paraglacial adjustment phase characterized by high sediment delivery efficiency. Slope reactivations occurred over periods up to 3400 years, with superimpositions of deposits: these are multi-phased RSFs.Finally, a significant lag of approximately 3000 years is observed between the deglaciation (~10.2 cal. ka BP) and the peak in rock-slope failure activity (8–6 cal. ka BP), which coincides with the Holocene Thermal Maximum climax in Iceland (8.6–5.2 cal. ka BP). The subsequent cessation of major RSFs activity after ~4 cal. ka BP marks the transition to a stable, non-glacial equilibrium
Promesses et limites des big data pour l’étude des pratiques sportives : le cas des applications de course à pied
No full textInternational audienceFor the past decade, editors of running apps have been exploiting the activity data generated by these digital devices, enriching it with questionnaires and publishing surveys on their users' practices. Based on enormous amounts of diverse data, the ambition is legitimate at first glance. However, several questions arise regarding the authority that tends to emanate from massive amounts of information, the volume of which does not guarantee its relevance. Combining documentary analysis and interviews, we examined the methodological validity of these studies, as well as the subsidiary contribution of this big data in relation to socio-demographic surveys on sports practices. This empirical work highlights significant weaknesses in terms of rigor and representativeness, as well as limited revelatory effects in relation to pre-existing knowledge. This does little to alter the belief in the informative potential of big data, which is considered meaningful by virtue of its massive scale. They allow for an overinterpretation marked by performativity, revealing the informational and communicational facet of data, which becomes a medium for narrative processes emphasizing rupture and novelty. Positioning oneself as a resource, or even a reference in terms of studies, statistics, and market data on running and its (r)evolutions takes precedence over the reliability of analyses and interpretive caution. Therefore, having access to large amounts of data, emphasizing its robustness, and then backing it up with descriptions that amplify real developments leads to taking on the elegant role of a pioneering descriptor of major trends of change.Résumé Depuis une dizaine d’années, des créateurs d’applications de course à pied exploitent les données d’activité générées par ces dispositifs numériques, les enrichissent de questionnaires et publient des enquêtes sur les pratiques de leurs utilisateurs. S’appuyant sur d’énormes quantités de données plurielles, l’ambition semble de prime abord légitime. Plusieurs questions se posent néanmoins quant au caractère d’autorité qui tend à émaner d’informations massives dont le volume ne garantit pas la pertinence. En combinant analyse documentaire et entretiens, nous nous sommes penchés sur la validité méthodologique de ces études, ainsi que sur l’apport subsidiaire de ces big data par rapport aux enquêtes socio-démographiques sur les pratiques sportives. Ce travail empirique met en évidence d’importantes fragilités en termes de rigueur et de représentativité, ainsi que des effets de révélation limités au regard des connaissances préexistantes. Cela n’altère guère la croyance dans le potentiel informatif des big data , considérées comme parlantes en vertu de leur dimension massive. Elles permettent une surinterprétation empreinte de performativité, révélant la facette info-communicationnelle de data devenant support de processus narratifs soulignant la rupture et la nouveauté. Se positionner comme une ressource, voire une référence en termes d’études, de statistiques et de données de marché sur la course à pied et ses (r)évolutions prend le dessus sur la fiabilité des analyses et la prudence interprétative. Dès lors, disposer de chiffres volumineux, asséner leur robustesse, puis y adosser des descriptions amplifiant les évolutions réelles conduisent à endosser l’élégant costume de descripteur pionnier de tendances lourdes de changement
Valoriser la production fruitière écologique du Pilat un projet de recherche-action
No full textThis work describes the co-design process for a fruit-growing region, aimed at promoting the ecological nature of fruit production, enabling farmers to earn a good income and offering them good working conditions, while promoting biodiversity, preserving natural resources and contributing to food security in the surrounding areas.Ces travaux décrivent les démarches de co-conception d'un territoire de production fruitière, visant à valoriser le caractère écologique de la production fruitière, permettant de bien rémunérer les agriculteurs et de leur offrir des bonnes conditions de travail tout en favorisant les biodiversité et préservant les ressources naturelles et en participant à la sécurité alimentaire des bassins de vie
Intrinsic training dynamics of deep neural networks
No full textA fundamental challenge in the theory of deep learning is to understand whether gradient-based training in high-dimensional parameter spaces can be captured by simpler, lower-dimensional structures, leading to so-called implicit bias. As a stepping stone, we study when a gradient flow on a high-dimensional variable implies an intrinsic gradient flow on a lower-dimensional variable , for an architecture-related function . We express a so-called intrinsic dynamic property and show how it is related to the study of conservation laws associated with the factorization . This leads to a simple criterion based on the inclusion of kernels of linear maps which yields a necessary condition for this property to hold. We then apply our theory to general ReLU networks of arbitrary depth and show that, for any initialization, it is possible to rewrite the flow as an intrinsic dynamic in a lower dimension that depends only on and the initialization, when is the so-called path-lifting. In the case of linear networks with the product of weight matrices, so-called balanced initializations are also known to enable such a dimensionality reduction; we generalize this result to a broader class of {\em relaxed balanced} initializations, showing that, in certain configurations, these are the \emph{only} initializations that ensure the intrinsic dynamic property. Finally, for the linear neural ODE associated with the limit of infinitely deep linear networks, with relaxed balanced initialization, we explicitly express the corresponding intrinsic dynamics
On the parameterized complexity of the Maker-Breaker domination game
No full textSince its introduction as a Maker-Breaker positional game by Duchêne et al. in 2020, the Maker-Breaker domination game has become one of the most studied positional games on vertices. In this game, two players, Dominator and Staller, alternately claim an unclaimed vertex of a given graph G. If at some point the set of vertices claimed by Dominator is a dominating set, she wins; otherwise, i.e. if Staller manages to isolate a vertex by claiming all its closed neighborhood, Staller wins. Given a graph G and a first player, Dominator or Staller must have a winning strategy. We are interested in the computational complexity of determining which player has such a strategy. This problem is known to be PSPACE-complete on bipartite graphs of bounded degree and split graphs; polynomial on cographs, outerplanar graphs, and block graphs; and in NP for interval graphs. In this paper, we consider the parameterized complexity of this game. We start by considering as a parameter the number of moves of both players. We prove that for the general framework of Maker-Breaker positional games in hypergraphs, determining whether Breaker can claim a transversal of the hypergraph in k moves is W[2]-complete, in contrast to the problem of determining whether Maker can claim all the vertices of a hyperedge in k moves, which is known to be W[1]-complete since 2017. These two hardness results are then applied to the Maker-Breaker domination game, proving that it is W[2]-complete to decide if Dominator can dominate the graph in k moves and W[1]-complete to decide if Staller can isolate a vertex in k moves. Next, we provide FPT algorithms for the Maker-Breaker domination game parameterized by the neighborhood diversity, the modular width, the P4-fewness, the distance to cluster, and the feedback edge number
