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BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20250611T130000
DTEND;TZID=Europe/Brussels:20250611T140000
DTSTAMP:20260405T182203
CREATED:20250602T090330Z
LAST-MODIFIED:20250605T133044Z
UID:2387-1749646800-1749650400@www.naxys.be
SUMMARY:Arash Rahimi-Iman (Justus-Liebig-Universität Gießen)
DESCRIPTION:Title : Machine learning optimization of chiral photonic metasurface: evolution-based algorithm and deep learning approach \nAbstract : \n\n\n\n\nChirality of light in the simplest case is given by the handedness of circular polarization\, for which handedness preserving or nonpreserving optics can be developed [1]. Chiral photonics has been receiving increased attention due to prospects of delivering tailored metamaterials with strong ‘chiroptical’ responses at predesignated wavelengths [2]\, as interactions between chiral light and matter could be attractive for applications ranging from chemistry to information processing. \nCircularly polarized electromagnetic waves incident on a nanopatterned metasurface can experience frequency-dependent filtering effects in reflection and/or transmission geometry. Such structures can be produced in thin-film dielectrics or metallic sheets. In a comparison of two machine learning optimization approaches\, the predicted chiral patterns (here in GaP) feature an increased circular dichroism [3]\, which resulted in a stronger reflectivity of right circularly than left circularly polarized waves compared to a simpler human-designed pattern. Outcomes from the multi-epoch design improvement procedure – through an evolution- and neural network-based algorithm – are discussed for a frequency-range-neutral comparative consideration promising for both (nano)printing or ablating of surface patterns\, and indicating further improvements potentials with more advanced algorithms. \nReferences: \n[1] E. Plum\, N. I. Zheludev (2015): Chiral Mirrors\, Appl.Phys.Lett. 106\, 221901. \n[2] W. Ma\, F. Cheng\, Y. Liu (2018): Deep-Learning-Enabled On-Demand Design of Chiral Metamaterials\, ACS Nano 12\, 6326. \n[3] O. Mey\, A. Rahimi-Iman (2021): Machine Learning-Based Optimization of Chiral Photonic Nanostructures: Evolution- and Neural Network-Based Designs\, Phys.Stat.Sol. RRL 16\, 202100571. \nThis seminar will take place in Room 266 at the Faculty of Sciences.
URL:https://www.naxys.be/event/arash-rahimi-iman-justus-liebig-universitat-giesen/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20250910T130000
DTEND;TZID=Europe/Brussels:20250910T140000
DTSTAMP:20260405T182203
CREATED:20250827T124235Z
LAST-MODIFIED:20251016T135515Z
UID:2404-1757509200-1757512800@www.naxys.be
SUMMARY:Denis Langevin (Université Clermont Auvergne)
DESCRIPTION:Title: Global optimization for inverse design in nanophotonics \nAbstract: \n\n\n\n\nGlobal optimization algorithms for the inverse design of nanophotonic structures is a tool which is providing increasingly convincing results – even though the wave nature of photonic behaviours makes them particularly complex. In the meantime\, the field of global optimization itself is rapidly evolving but is prone to reproducibility problems\, making it harder to identify the right algorithms to use. \nIn this talk\, I will provide a physicist’s insight into the specificities about photonic problems\, and how they help or hinder us when using optimisation tools. I will present “observables” – such as spontaneous emergence of regularity or consistency curves – which are relevant for judging the reliability of an optimization and the quality of the generated solution. To support this discussion\, I will draw on benchmark examples covering a broad range of topics\, including 1D\, 2D\, 3D problems. \nReferences: \n[1] Barry\, M. A.\, Berthier\, V.\, Wilts\, B.. D.\, Cambourieux\, M.-C.\, Bennet\, P.\, Pollès\, R.\, Teytaud\, O.\, Centeno\, E.\, Biais\, N.\, and Moreau\, A.\, “Evolutionary algorithms converge towards evolved biological photonic structures\,” Scientific reports 10(1)\, 1–10 (2020). \n[2] Sörensen\, K.\, “Metaheuristics—the metaphor exposed\,” International Transactions in Operational Research 22(1)\, 3–18 (2015). \n[3] Bennet\, P.\, Langevin\, D.\, Essoual\, C.\, Khaireh-Walieh\, A.\, Teytaud\, O.\, Wiecha\, P.\, and Moreau\, A.\, “An illustrated tutorial on global optimization in nanophotonics\,” (2023). \nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/denis-langevin-universite-clermont-auvergne/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20251016T130000
DTEND;TZID=Europe/Brussels:20251016T140000
DTSTAMP:20260405T182203
CREATED:20250909T084321Z
LAST-MODIFIED:20251016T135220Z
UID:2407-1760619600-1760623200@www.naxys.be
SUMMARY:Alessandro Moirano (LPAP\, ULiège)
DESCRIPTION:Title: Io\, a natural probe for Jupiter’s atmosphere and magnetosphere – (Some of) Juno’s results on the moon-magnetosphere interaction. \nAbstract: \n\n\n\n\n\nJupiter hosts persistent and bright auroras\, which are driven by the precipitation of particles into its atmosphere\, mostly electrons. The presence of Io orbiting in the inner Jovian magnetosphere produce a specific auroral emission on Jupiter\, called “footprint”\, whose details are determined by the atmosphere and the energy of the precipitating electrons. The latter\, in turn\, depends on the physical  magnetospheric process(es) that accelerates the particles along the magnetic field and towards the planet. Therefore\, the footprint – and the aurora in general – wraps information about the atmospheric structure and the energy spectrum of the precipitation. During this talk\, we will discuss the recent analyses of the observations performed by Juno\, which has been orbiting Jupiter and providing an unprecedented vantage point on its polar regions since 2016.  To begin with\, the position of the Io footprint is affected by the Io plasma torus\, a dense and variable plasma cloud around Io’s orbit that is ultimately produced by the volcanic activity on the moon. We were able to constrain the spatial distribution of plasma near Io thanks to several years of observations with Juno. Moreover\, during some of the closest-approach to Jupiter\, Juno was able to observe the Io footprint near the planetary limb\, which provided a unique opportunity to investigate the relation between the spectrum of the precipitating electrons and the vertical profile of the auroral emission. Lastly\, by looking at the absorption in the far-ultraviolet recorded with the Ultraviolet Spectrograph onboard Juno\, we aim at estimating the hydrocarbon abundances in the upper layers of Jupiter’s atmosphere. \n\n\nThe seminar mostly presents results driven by observations\, interpreted in light of current theoretical models. Infrared\, ultraviolet and radio observations\, as well as in-situ particle measurements\, are the backbone of the talk\, although the moon-magnetosphere interaction welcome all types of expertise and observations. \n\nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/alessandro-moirano-uliege/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20251021T130000
DTEND;TZID=Europe/Brussels:20251021T140000
DTSTAMP:20260405T182203
CREATED:20250923T065604Z
LAST-MODIFIED:20250924T152429Z
UID:2411-1761051600-1761055200@www.naxys.be
SUMMARY:Isao Ishikawa (Kyoto University)
DESCRIPTION:Title: Finite dimensional approximations of push-forwards on analytic functionals \nAbstract: \nIn this talk\, we will introduce JetEDMD\, a new theoretical framework as a finite-dimensional approximation of the push-forward on the spaces of analytic functionals.\nJetEDMD provides a reasonable modification of Extended Dynamic Mode Decomposition (EDMD) and elucidates new mathematical machinery by combining the structure of reproducing kernel Hilbert spaces with the jet spaces on the state space of the dynamical system.\n\nAs applications\, I will present methods for the data-driven estimation of equilibrium points and the reconstruction of vector fields from discrete trajectory data with a rigorous convergence result. Finally\, I will discuss some current mathematical challenges and future research directions within this framework.
URL:https://www.naxys.be/event/isao-ishikawa-kyoto-university/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20251022T150000
DTEND;TZID=Europe/Brussels:20251022T163000
DTSTAMP:20260405T182203
CREATED:20251016T135626Z
LAST-MODIFIED:20251016T140440Z
UID:2585-1761145200-1761150600@www.naxys.be
SUMMARY:Laura Gagliardi (University of Chicago)
DESCRIPTION:Title: Reticular frameworks after the Nobel prize: their application for catalysis and CO2 capture \nAbstract: \n\n\n\n\n\nFollowing reflection on the 2025 Nobel Prize in Chemistry awarded for advances in metal– organic frameworks (MOFs)\, this lecture explores how state-of-the-art quantum chemical and classical simulations are driving the discovery of reticular materials. Computation today is not only a tool to rationalize experiments\, but increasingly a predictive engine for tailoring functional frameworks. \nIn the first part of the presentation\, I will highlight our integrated computational and experimental study of catalytic MOFs\, where post-synthetic modification introduced metal– sulfur active sites [1]. Quantum chemical calculations elucidated how sulfur incorporation modulates the electronic structure and catalytic reactivity of the frameworks. These insights provided a mechanistic understanding of hydrogenation catalysis and guided the design of MOFs with tunable properties. \nThe second part will focus on covalent organic frameworks (COFs). Thanks to their modular architectures and tunable functionalities\, COFs offer a highly versatile platform for CO2 direct air capture. We performed a multiscale investigation of COF-999 and its amine- functionalized precursor COF-999-NH₂\, integrating density functional theory\, molecular dynamics\, and grand canonical Monte Carlo simulations with experimental validation [2]. Our findings highlight subtle energy differences in laterally shifted stackings\, intrinsic stacking heterogeneity\, and pronounced layer buckling. We found that extensive amine– nitrile hydrogen bonding and persistent pore water lead to undesired polymerization that undermines CO₂ uptake. The predicted presence of water is confirmed by subsequent experiments. These insights point to a single\, actionable design rule: exclude retained water by introducing hydrophobic pore environments to maximize CO2 capture efficiency. \n[1] H. Xie\, M. A. Khoshooei\, M. Mandal\, S. M. Vornholt\, J. Hofmann\, L. M. Tufaro\, K. O. Kirlikovali\, D. A. Grimes\, S. Lee\, S. Su\, S. Reischauer\, D. Sengupta\, K. Fahy\, K. Ma\, X. Wang\, F. Sha\, W. Gong\, Y. Che\, J. G. Vitillo\, J. S. Anderson\, J. M. Notestein\, K. W. Chapman\, L. Gagliardi\, and O. K. Farha\, Introducing Metal–Sulfur Active Sites in Metal–Organic Frameworks Via Post-Synthetic Modification for Hydrogenation Catalysis\, Nature Chemistry\, 2025. DOI: 10.1038/s41557-025-01876-y \n[2] H. Daglar\, Z. Zhou\, R. Zhu\, P. Parihar\, J. I. Siepmann\, O. M. Yaghi\, L. Gagliardi Discovery of Stacking Heterogeneity\, Layer Buckling\, and Residual Water in COF-999-NH₂ and Implications on CO2 Capture Submitted (2025) \n\nThis seminar will take place in Room S05 at the Faculty of Sciences.
URL:https://www.naxys.be/event/laura-gagliardi-university-of-chicago/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20251127T130000
DTEND;TZID=Europe/Brussels:20251127T140000
DTSTAMP:20260405T182203
CREATED:20251003T151749Z
LAST-MODIFIED:20251126T131919Z
UID:2579-1764248400-1764252000@www.naxys.be
SUMMARY:Serge Nicaise (Université de Valenciennes)
DESCRIPTION:Title: Stability results of dissipative systems via the frequency domain approach \nAbstract: \n\n\n\n\nThe frequency domain approach goes back to J. Prüss [Trans. Amer. Math. Soc. 284 (1984)\, 847-857] and F. L. Huang [Ann. Differential Equations 1 (1985)\, 43-56] that show that a C0 semigroup (etA)t≥0 of contractions in a Hilbert space H is exponentially stable if and only if the resolvent of A is uniformly bounded on the imaginary axis. Afterwards Z. Liu and B. Rao\, [Z. Angew. Math. Phys. 56 (2005)\, 630-644]\, C. J. K. Batty and T. Duyckaerts [J. Evol. Equ. 8 (2008)\, 765-780]\, and A. Bátkai\, K.-J. Engel\, J. Prüss and R. Schnaubelt [Math. Nachr. 279 (2006)\, 1425-1440] have given some sufficient conditions on the behavior of the resolvent of A on the imaginary axis that guarantee an almost polynomial decay of the semigroup. Finally an optimal result about the polynomial decay was found by A. A. Borichev and Yu. V. Tomilov [Math. Ann. 347 (2010)\, 455-478]. This approach is a powerful tool for the study of the decay of the semigroup associated with concrete dissipative systems since it reduces to the study of the resolvent on the imaginary axis. \nIn my talk\, I will first recall these two results and then illustrate them on two particular dissipative systems. \n\nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/serge-nicaise-universite-de-valenciennes/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20260129T130000
DTEND;TZID=Europe/Brussels:20260129T140000
DTSTAMP:20260405T182203
CREATED:20260113T132042Z
LAST-MODIFIED:20260121T154806Z
UID:2609-1769691600-1769695200@www.naxys.be
SUMMARY:session pitch naXys
DESCRIPTION:“Coexistence and stability in ecological systems” (Frederik De Laender)\n“Measuring and implementing sustainability in finance: The need for systemic approaches” (Sophie Béreau)\n“Analysis of the control system mechanisms of robots” (Elio Tuci)\n“Rare trajectories in quantum field theory and classical dynamics” (Yves Caudano)\n“Emergent properties of complex systems. A tale of networks and nonlinearity” (Timoteo Carletti) \nThis seminar will take place in Room S09 at the Faculty of Sciences.
URL:https://www.naxys.be/event/session-pitch-naxys/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20260211T130000
DTEND;TZID=Europe/Brussels:20260211T140000
DTSTAMP:20260405T182203
CREATED:20260205T084741Z
LAST-MODIFIED:20260206T075147Z
UID:2627-1770814800-1770818400@www.naxys.be
SUMMARY:Diego Samuel Rodrigues (University of Campinas\, SP\, Brazil)
DESCRIPTION:Title: Parameter Estimation for Ordinary Differential Equation Models in Cancer Research \nAbstract:  \nInferring parameter values from data is a fundamental problem in quantitative oncology. This seminar offers a concise\, example-driven overview of parameter estimation and experimental design for ordinary differential equation systems\, bridging theoretical foundations with practical applications in cancer research.\n\nThis seminar will take place in Room S0 at the Faculty of Sciences.
URL:https://www.naxys.be/event/diego-samuel-rodrigues-university-of-campinas-sp-brazil/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20260226T130000
DTEND;TZID=Europe/Brussels:20260226T140000
DTSTAMP:20260405T182203
CREATED:20251219T105508Z
LAST-MODIFIED:20260220T133944Z
UID:2599-1772110800-1772114400@www.naxys.be
SUMMARY:Federica Garin (Université Grenoble Alpes)
DESCRIPTION:Title: Graphons and opinion dynamics on large graphs. \nAbstract: \nGraphons are the limits of large dense graphs. Graphons can also be used to define families of random graphs (the so-called W-random graphs)\, similar to Erdős-Rényi random graphs but with some inhomogeneity in the edge probabilities. \nGraphons and W-random graphs\, together with their signed counterparts\, can be useful tools to study opinion dynamics on large-scale networks.  \nIn this talk\, I will review some recent work in this direction\, where we explore some infinite-dimensional dynamics associated with the graphon\, and we study how well they can approximate the corresponding dynamics associated with finite but large W-random graphs. \n  \nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/federica-garin-universite-grenoble-alpes/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20260416T130000
DTEND;TZID=Europe/Brussels:20260416T140000
DTSTAMP:20260405T182203
CREATED:20251219T105754Z
LAST-MODIFIED:20260325T102327Z
UID:2603-1776344400-1776348000@www.naxys.be
SUMMARY:Thomas Koffel (Université Claude Bernard Lyon 1)
DESCRIPTION:Title: From Metacommunities to Masting: How Spatial Structure Privatizes Environmental Benefits \nAbstract:  \nIndirect positive interactions\, mediated by environmental modification\, are central to niche construction and cooperation. However\, eco-evolutionary theory predicts that when modified environments are fully public\, the ‘tragedy of the commons’ favors cheaters\, destabilizing such processes. This talk explores how spatial structure overcomes this barrier through two complementary lines of work. First\, using a minimal stochastic model\, we show how competition-colonization dynamics in a patch-structured metacommunity allow cooperators to coexist with or even exclude cheaters. Second\, we demonstrate how environmental privatization at the individual level enables niche construction\, specifically in the context of masting (intermittent\, synchronous fruiting by trees). By satiating and starving seed consumers—a ‘public bad’—masting evolves as a coordinated defense strategy that effectively privatizes the benefits of predator control. Together\, these results underline how the scale of environmental modification fundamentally dictates the scale at which selection acts in ecosystems. \nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/thomas-koffel-universite-claude-bernard-lyon-1/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20260507T130000
DTEND;TZID=Europe/Brussels:20260507T140000
DTSTAMP:20260405T182203
CREATED:20260404T070617Z
LAST-MODIFIED:20260404T070741Z
UID:2653-1778158800-1778162400@www.naxys.be
SUMMARY:Koichiro Yawata (Institute of Science\, Tokyo)
DESCRIPTION:Title: Reduced-Order Control of Coupled Phase Oscillator Populations and Hypergraph-Based Approaches to Combinatorial Optimization Problems\n \nAbstract:  \nIn this seminar\, I will present two recent pieces of work from my research: one on reduced-order control of coupled oscillator populations and another on hypergraph-based approaches to combinatorial optimization. \n1. Reduced-Order Control of Coupled Oscillator Populations via Frequency-Dependent Forcing\nWe propose a frequency-dependent forcing framework for heterogeneous populations of coupled phase oscillators. Using the Ott-Antonsen ansatz\, we derive a low-dimensional description of the collective dynamics and study control methods for the macroscopic phase and synchronization level. \n2. Hypergraph Neural Networks Accelerate MUS Enumeration\nWe propose a hypergraph-neural-network-based method for accelerating MUS enumeration in constraint satisfaction problems. By combining hypergraph modeling with reinforcement learning\, the method reduces satisfiability checks and improves enumeration efficiency. \nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/koichiro-yawata-institute-of-science-tokyo/
CATEGORIES:NAXYS Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=Europe/Brussels:20261001T130000
DTEND;TZID=Europe/Brussels:20261203T140000
DTSTAMP:20260405T182203
CREATED:20260402T100822Z
LAST-MODIFIED:20260402T100906Z
UID:2650-1790859600-1796306400@www.naxys.be
SUMMARY:Nelly Litvak (Eindhoven University of Technology)
DESCRIPTION:Title:  \nAbstract:  \nThis seminar will take place in Room S08 at the Faculty of Sciences.
URL:https://www.naxys.be/event/nelly-litvak-eindhoven-university-of-technology/
CATEGORIES:NAXYS Seminar
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