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Multi-method constraints on late Pleistocene glacier fluctuations in the Ossau valley (SW France), with wider implications for the Pyrenean icefield during the last glacial maximum
No full textInternational audienceCurrent evidence throughout the Pyrenees indicates that the local last glacial maximum (LLGM) of the Late Pleistocene occurred earlier than the globally recognised LGM period (26-19 ka). Some LGM glaciers subsequently grew to sizes similar to those of their LLGM predecessors, but others fell short. These apparent differences have been attributed either to peculiar palaeoprecipitation patterns across the mountain range or to artifacts among the different dating methods underpinning the glacier fluctuation chronologies. Here we test these two alternatives by presenting 33 new ¹⁰Be and ³⁶Cl surface exposure ages from the terminal moraines of the Ossau valley, by elaborating 3D glacial reconstructions fitted to successive generations of landforms, and by discussing the data in light of published ¹⁴C ages from the nearby Estarrès threshold-lake glaciolacustrine sequence and from several archaeological sites. Results indicate that a first major glacier advance occurred at some time before 35 ka cal BP, after which the Ossau glacier receded by 4 km between 34-30 ka and 31-27 ka cal BP. A subsequent readvance generated LLGM moraines ca. 22.7 ka, followed by post-LLGM recessional moraines (age: 20.2 ka) positioned 2 km to the south. Around 19 ka cal BP, the glacier retreated by a further 30 km. By revealing an interval of maximum glacier growth during the LGM, this new chronology suggests that the distinction between LGM and LLGM in the Pyrenees may increasingly become obsolete as multi-method approaches help to refine Late Pleistocene icefield fluctuation patterns in other valleys
Involutions de Möbius
No full textWe revisit and extend the classical theory of M\"obius involutions, presenting a unified geometric framework that highlights their ubiquity and utility in similarity geometry and mathematical physics. We analyze compositions of spiral similarities, clarifying how dilation factors, rotation angles, and the often‑overlooked relations among fixed points interact under composition. Reinterpreting these phenomena via M\"obius involutions yields simpler proofs and sharper structural insights. We treat indirect involutions (inversions), give a complete account of three pairwise commuting inversions, and prove Ramondou’s recent conjecture on elliptic and hyperbolic pencils of circles. Finally, we introduce a novel similarity geometry on pairs of points exchanged by a fixed M\"obius involution, define collinearity and concyclicity in this setting, and present applications that simultaneously exchange multiple classical point pairs. The results synthesize historical sources with new observations and demonstrate that M\"obius involutions are both fundamental and practically powerful in geometry
Initiation of Regularized Cracks is Explained by the Coupled Criterion
No full textInternational audienceMatched asymptotic expansions and phase-field regularization are combined to propose an implementation of the coupled criterion that accounts for the presence of an initial process zone. The initial process zone is introduced by prescribing phase-field Dirichlet boundary conditions around the crack initiation location, which allows us to study either sharp or regularized crack initiation through an initial process zone. An increase in the initially prescribed phase-field value enlarges the effective process zone and progressively reduces the stress singularity at the V-notch tip, showing that even a partially developed process zone can mitigate singular stresses through non-uniform stiffness, without requiring plastic regularization. Furthermore the process zone tends to decrease the incremental energy release rate, thus resulting in a higher initiation generalized stress intensity factor than the one obtained without an initial process zone. The findings reveal that, unlike Griffith's singular formulation, the phase-field model remains intrinsically regularized -even in the vanishing-length limit -raising the fundamental question of whether truly sharp cracks can exist or if a finite process zone always emerges through local structural rearrangement. The proposed approach thus extends the coupled criterion to study crack initiation and propagation in quasi-brittle materials
Purified and biocompatible magnetoliposomes highly loaded with superparamagnetic iron oxide nanoparticles (SPIONs)
No full textInternational audienc
When Curvature Counts: Hyperbolic Geometry in Prototype-Based Image Classification
No full textInternational audiencePrototype Learning offers an interpretable and efficient classification framework by mapping data into an embedding space structured around class prototypes. Recent research has explored non-Euclidean geometries, such as hyperspherical and hyperbolic spaces, to more effectively model latent hierarchical structures and complex data relationships. While these geometries have shown potential, leveraging them within an image classification context is not trivial. To address this, we propose HypPNet, a hyperbolic prototypical model on the Poincaré ball that integrates Riemannian optimization and norm-based regularization to perform effectively without prior data knowledge. Experiments on three benchmark datasets and multiple embedding dimensions show that HypPNet outperforms its competitors across alternative geometries, improving classification performance over various metrics
High-Pressure High-Temperature Nanodiamond-Modified ZnO Nanocomposites as Promising Photocatalysts: Synthesis and Characterization
No full textInternational audienceZinc oxide (ZnO) nanostructures suffer from fast electron–hole recombination, limiting their applicability in photocatalytic environmental remediation, and carbon additives such as detonation nanodiamonds (DNDs) are constrained by their high defect density. To address this, ZnO nanocomposites modified with high-pressure, high-temperature nanodiamonds (HPHT NDs) were synthesized to evaluate whether their intrinsically lower defect density—evidenced by a dominant diamond Raman peak at 1330 cm−1 and a low sp2 carbon fraction of 6.6% compared to oxidized DNDs with strong D/G bands (~1350/1580 cm−1) and ~25–35% sp2 carbon—can enhance charge separation and improve photocatalytic activity. Oxidized HPHT NDs bearing carbonyl, carboxyl, and hydroxyl groups enabled covalent attachment to ZnO, and the resulting ND–ZnO composites were characterized by SEM/EDX, ATR-FTIR, Raman spectroscopy, XPS, and cathodoluminescence (CL). EDX confirmed increasing carbon incorporation from 13.0 to 52.9 at.%, while XPS revealed a 0.5 eV shift in the Zn 2p3/2 peak and an increase in Zn–O–Zn lattice oxygen from 31.3% to 61.6% in ND–ZnO 10. CL showed enhanced near-band-edge emission and reduced Zni-related luminescence (~3.0 eV). ND–ZnO 10 achieved a nearly threefold-higher degradation rate constant (0.0251 min−1) than pristine ZnO (0.0087 min−1) and retained 88% efficiency after five cycles, demonstrating strong potential for durable wastewater treatmen
CVRPLIB BKS challenge : The MAMUT approach
No full textInternational audienceCVRPLIB BKS challenge : The MAMUT approac
Review of "Fracture Toughness of Periodic Beam Lattices"
No full textOpen Review of "Fracture Toughness of Periodic Beam Lattices" publised in JTCAM
Breaking the 3D Dataset Bottleneck: Fast Scalable Generation of Aligned 3D Assets from Scratch for Category 6D Pose Estimation and Robotic Grasping
No full textInternational audienceWhile 2D vision has been revolutionized by large-scale datasets like ImageNet, 3D vision remains constrained by the scarcity of high-quality, canonically aligned data. We introduce the first scalable, automated framework that generates complete category-level 6D pose datasets directly from text prompts, bypassing the need for existing 3D assets. Our method overcomes key challenges by: (1) ensuring reliable, scalable asset generation via a controlled text-to-image-to-3D pipeline; (2) enforcing built-in canonical alignment through depth-conditioned generation, achieving a 96\% pose consistency rate; and (3) enabling large-scale 6D annotation via mixed reality rendering. The pipeline produces high-quality, aligned 3D meshes in under 3 minutes per object—a 5–20 speedup over traditional scanning. We generate over 1,000 instances for each of the 153 categories in the Omni6Dpose benchmark, culminating in 153,000 aligned meshes—a >40 increase in instances per category over previous aligned real-world datasets. Extensive evaluation demonstrates competitive zero-shot sim2real transfer on the NOCS 6D pose benchmark and superior robotic grasping performance in both simulation and real-world zero-shot transfer, where aligned meshes prove essential for success. We release the largest publicly available aligned 3D mesh dataset, largest category-level 6D pose dataset, grasping simulation environments, and open-source pipeline, providing a critical step toward foundation models for 3D understanding and enabling efficient, unlimited generation of task-specific 3D data from scratch