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Braiding Vineyards
No full textFull version of a paper accepted to SODA26In this work, we introduce and study what we believe is an intriguing and, to the best of our knowledge, previously unknown connection between two fundamental areas in computational topology, namely topological data analysis (TDA) and knot theory. Given a function from a topological space to R, TDA provides tools to simplify and study the importance of topological features: in particular, the l th -dimensional persistence diagram encodes the topological changes (or l-homology) in the sublevel set as the function value increases into a set of points in the plane. Given a continuous one-parameter family of such functions, we can combine the persistence diagrams into an object known as a vineyard, which track the evolution of points in the persistence diagram as the function changes. If we further restrict that family of functions to be periodic, we identify the two ends of the vineyard, yielding a closed vineyard. This allows the study of monodromy, which in this context means that following the family of functions for a period permutes the set of points in a non-trivial way.Recent work has studied monodromy in the directional persistent homology transform, demonstrating some interesting connections between an input shape and monodromy in the persistent homology transform for 0-dimensional homology embedded in R^2 . In this work, given a link and a value l, we construct a topological space (based on the given link) and periodic family of functions on this space (based on the Euclidean distance function), such that the closed l-vineyard contains this link. This shows that vineyards are topologically as rich as one could possibly hope, suggesting many future directions of work. Importantly, it has at least two immediate consequences we explicitly point out: • Monodromy of any periodicity can occur in a l-vineyard for any l. This answers a variant of a question by Arya and collaborators [4]. To exhibit this as a consequence of our first main result we also reformulate monodromy in a more geometric way, which may be of interest in itself. • Topologically distinguishing closed vineyards is likely to be difficult (from a complexity theory as well as a practical perspective) because of the difficulty of knot and link recognition, which have strong connections to many NP-hard problems
ATREIDES 1: Embarking on a trek across the exo-Neptunian landscape with the TOI-421 system
No full textInternational audienceThe distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. The Desert, Ridge, and Savanna (respectively a lack, overoccurence, and mild deficit of Neptunes with increasing periods) illustrate the sensitivity of these worlds to such processes, making them ideal targets to disentangle their roles. Determining how many Neptunes are brought close-in by early disk-driven migration (DDM; expected to maintain primordial spin-orbit alignment) or late high-eccentricity tidal migration (HEM; expected to generate large misalignments) is essential to understanding how much atmosphere they lost. In this paper, we propose a unified view of the exo-Neptunian landscape to guide its exploration and speculate that the Ridge is a hot spot for evolutionary processes. Low-density Neptunes would mainly undergo DDM, becoming fully eroded at shorter periods than the Ridge. This is in contrast to denser Neptunes, which would be brought to the Ridge and Desert by HEM. We embark on this exploration via the ATREIDES (Ancestry, Traits, and Relations of Exoplanets Inhabiting the Desert Edges and Savanna) collaboration, which relies on spectroscopic and photometric observations of ~60 close-in Neptunes, their reduction with robust pipelines, and their interpretation through internal structure, atmospheric, and evolutionary models. We carried out a systematic Rossiter-McLaughlin census with VLT/ESPRESSO to measure the distribution of 3D spin-orbit angles, correlate its shape with the system properties (orbit, density, evaporation), and thus relate the fraction of aligned-misaligned Neptunian systems to DDM, HEM, and atmospheric erosion. The first ATREIDES target, TOI-421 c, lies in the Savanna with a neighboring sub-Neptune TOI-421 b. We measured for the first time their 3D spin-orbit angles ( ψ b = 57 −15 +11∘ ; ψ c = 44.9 −4.1 +4.4∘ ). Together with the eccentricity and possibly large mutual inclination of their orbits, this hints at a chaotic dynamical origin that could result from DDM followed by HEM. Our program will provide the community with a wealth of constraints for formation and evolution models, and we welcome collaborations that will contribute to pushing our understanding of the exo-Neptunian landscape forward
Créer ou réveler l'inclusion là où on ne l'attend pas ? Pratiques de (dés)engagement des travailleurs musulmans sur les plateformes de livraison
No full textInternational audienceCe chapitre met en lumière les dynamiques d'engagement des travailleurs musulmans pratiquants dans les plateformes de livraison de nourriture, en suggérant que les opportunités d'expression religieuse contribuent à la pérennisation du modèle économique de ces plateformes. Alors que les travailleurs migrants musulmans ont historiquement été victimes de discrimination dans les organisations traditionnelles, travailler sur des plateformes médiées par des algorithmes leur permet d'exprimer leur religiosité et de développer des pratiques autonomes, pour trouver une forme d'inclusion construite. Nos résultats nous permettent d’esquisser une typologie des différentes formes de conciliation entre identité et professionnalité des livreurs musulmans sur les plateformes, qui les perçoivent soit comme un espace de travail par défaut, un refuge temporaire, un espace de réalisation de soi inclusif ou une transition vers de meilleures conditions de travail. Enfin, nous soutenons que cette conciliation entre identités personnelle et professionnelle contribue au maintien du statu quo dans une économie des plateformes inégalitaire, car les plateformes se légitiment à travers un travail institutionnel auprès des autorités publiques, mais aussi en fidélisant leurs communautés de travailleurs
Embodied Virtual Instruments in Web-Based Multi-User VR: A Case Study with a 3D Drum Kit and Web Audio Modules
No full textInternational audienceWAM Jam Party is a web-based, multi-user VR application that enables participants to collaboratively build musical experiences by visually manipulating an audio signal chain composed of interactive audio nodes. Users can create, modify, and route sound by adding or connecting these nodes, each being a WAM (Web Audio Module) plugin with a 3D GUI. WAMs are often described as the web equivalent of VST plugins. Available 3D WAMs include synthesizers, samplers, audio effects, and pattern-based music note generators such as piano rolls or step sequencers, though traditional instrument metaphors have not yet been incorporated.This article explores our efforts to enhance interactivity within this environment by introducing embodied virtual instruments -interfaces designed to replicate real-world instrumental interaction as closely as possible. Our initial focus is the development of a virtual drum kit (composed of several 3D meshes) that generates MIDI notes (including velocity), connected to a 3D drum sampler WAM and implemented using the Havok physics engine used in many AAA video games, for realistic collision detection with the virtual drumsticks that follow the user's movements. We aimed to simulate a drummer's physical gestures using VR controllers, while also addressing audio responsiveness, haptic feedback, and synchronized visual cues (i.e animating the 3D meshes during impacts) to reinforce the sense of embodied performance. During the demonstration, participants will be equipped with VR headsets to interact directly with the virtual drum kit environment. A secondary display will mirror the VR user's viewpoint, enabling observers to monitor the real-time immersive experience.</p
Role of platinum-free interval (PFI) and maintenance therapies in recurrent ovarian cancer to explain survival. An analysis from the French real-world ESME Ovarian Database
No full textInternational audienceObjective: Approximately 70 % of patients with epithelial ovarian cancer (EOC) will relapse. Beyond the platinum-free interval (PFI), predictive factors for efficacy of subsequent therapies are poorly understood. We evaluated the impact of the PFI on progression-free survival (PFS), overall survival (OS) and the role of therapies used at relapse.Methods: This retrospective study using the French ESME Ovarian Database included patients with first relapse of EOC after front-line platinum-based chemotherapy (PBCT). The impact of prognostic factors on survival was analyzed using multivariate Cox regression, with results expressed as hazard ratios, adjusted for patient and tumor characteristics, including a subgroup analysis of high-grade serous cancer.Results: 5558 patients, treated between 2010 and 2019 were included (median age 65 IQR 57-71). Median second- and third line PFS and OS were proportionally higher with PFI prolongation. Other factors influencing PFS and OS were BRCA mutation, FIGO stage, chemotherapy and maintenance regimens, and PS. PBCT was more effective than single-agent chemotherapy, even with a PFI < 6 months (PFSn2: adjusted HR = 0.48 95 %IC [0.43;0.53], OSn2: HR = 0.51 95 %IC [0.46;0.57]). Use of PARP inhibitors (PARPi) in second line seems to reduce outcomes in the third line. Findings were consistent in the HGSC subgroup.Conclusion: PFI remains an important prognostic factor but should no longer be the sole consideration for treatment selection at relapse in EOC, particularly in HGSC. The potential impact of prior PARPi maintenance on subsequent PBCT warrants investigation in prospective trials
Metropolitan quantum key distribution using a GaN-based room-temperature telecommunication single-photon source
No full textInternational audienceSingle-photon sources (SPS) hold the potential to enhance the performance of quantum key distribution (QKD). QKD systems using SPS often require cryogenic cooling, while recent QKD attempts using SPS operating at room-temperature have failed to achieve long-distance transmission due to the SPS not operating at telecommunication wavelength. In this work, we have successfully demonstrated QKD using a room-temperature SPS at telecommunication wavelength. The SPS used in this work is based on point defects hosted by gallium nitride (GaN) thin films grown on sapphire substrates. We employed a time-bin and phase encoding scheme to perform the BB84 and reference-frame-independent QKD protocols over a 33 km fiber spool, achieving a secure key rate of per pulse. Moreover, we also implemented a metropolitan QKD experiment over a 30 km deployed fiber, achieving a secure key rate of per pulse. These results broaden the prospects for future use of SPS in commercial QKD applications
Intégrales asymptotiques, sur le disque, du champ magnétique généré par une aimantation rémanente
No full textA sample carrying a remanent magnetization produces a magnetic field around it. We establish asymptotic expressions of some integrals related to this field, assuming that it is measured on a horizontal disk above the sample, with a radius much bigger than the characteristic size of the sample. These integrals allow one to obtain estimates of the net magnetic moment of the sample.Un échantillon porteur d'une aimantation rémanente génère un champ magnétique tout autour de lui. En supposant que le champ est mesuré sur un disque horizontal situé au dessus de l'échantillon et dont le rayon est grand par rapport aux dimensions caractéristiques de ce dernier, nous établissons les expressions asymptotiques de certaines intégrales reliées au champ magnétique. Ces intégrales permettent d'obtenir une estimation du moment magnétique net de l'échantillon