@article{20980, abstract = {Morse decompositions partition the flows in a vector field into equivalent structures. Given such a decomposition, one can define a further summary of its flow structure by what is called a connection matrix. These matrices, a generalization of Morse boundary operators from classical Morse theory, capture the connections made by the flows among the critical structures—such as attractors, repellers, and orbits—in a vector field. Recently, in the context of combinatorial dynamics, an efficient persistence-like algorithm to compute connection matrices has been proposed in Dey, Lipiński, Mrozek, and Slechta [SIAM J. Appl. Dyn. Syst., 23 (2024), pp. 81–97]. We show that, actually, the classical persistence algorithm with exhaustive reduction retrieves connection matrices, both simplifying the algorithm of Dey et al. and bringing the theory of persistence closer to combinatorial dynamical systems. We supplement this main result with an observation: the concept of persistence as defined for scalar fields naturally adapts to Morse decompositions whose Morse sets are filtered with a Lyapunov function. We conclude by presenting preliminary experimental results.}, author = {Dey, Tamal K. and Haas, Andrew and Lipiński, Michał}, issn = {1536-0040}, journal = {SIAM Journal on Applied Dynamical Systems}, number = {1}, pages = {108--130}, publisher = {Society for Industrial & Applied Mathematics}, title = {{Computing a connection matrix and persistence efficiently from a morse decomposition}}, doi = {10.1137/25m1739406}, volume = {25}, year = {2026}, } @article{20986, abstract = {During complex vocal interactions, different features of acoustic stimuli are integrated to produce appropriate vocal responses,1 such as copying sounds during vocal matching behavior in some animals.2,3,4,5,6,7,8,9,10,11,12 However, little is known about the interplay and possible trade-offs between the different temporal and spectral acoustic features during these vocal exchanges.2,13,14 Nightingales can flexibly match the pitch of their tonal “whistle songs” in real time during counter-singing duels.15,16 Here, we show that the syllable duration of whistle playbacks could alter the song responses of wild nightingales, causing their whistle duration distribution to shift toward the presented stimulus duration. When exposed to whistle playbacks featuring unnatural combinations of pitch and duration, nightingales demonstrate a flexible trade-off between pitch matching and temporal imitation, yet they are constrained by their vocal repertoire. They selectively adapted their vocal responses to approximate these novel stimuli, aligning them with their natural whistle repertoire. We developed a computational model of nightingale whistle-matching behavior that revealed a hierarchical organization of acoustic feature production. During whistle matching, the feature integration process is constrained by the duration of syllables, and pitch matching follows within this temporal framework, forcing a trade-off between the two features. Our findings reveal a complex interplay between the spectral and temporal domains that shapes song-matching behavior.}, author = {Calderon Garcia, Juan Sebastian and Costalunga, Giacomo and Vogels, Tim P and Vallentin, Daniela}, issn = {1879-0445}, journal = {Current Biology}, publisher = {Elsevier}, title = {{Interplay between syllable duration and pitch during whistle matching in wild nightingales}}, doi = {10.1016/j.cub.2025.12.025}, year = {2026}, } @article{21001, abstract = {Copper chalcogenides offer high charge mobility and low lattice thermal conductivity but suffer from structural instability due to dynamic Cu+ migration. Here, we report a colloidal hot-injection synthesis of ternary cesium copper selenide (CsCu5Se3) nanocrystals (NCs), achieving precise control over phase, size, and morphology through tailored precursor-ligand modulation. This strategy enabled systematic exploration of stable and metastable Cs–Cu–Se phases and mechanistic investigation of nucleation and growth, providing insight into phase modulation and dimensional control at the nanoscale. CsCu5Se3 NCs exhibit low lattice thermal conductivity (∼0.5 Wm–1K–1) and an experimental zT of 0.27 at 718 K. Complementary first-principles calculations, consistent with experimental electronic and optical responses, predict a zT of 1.05 at 1000 K. These findings elucidate the formation dynamics of CsCu5Se3 and establish ABZ (A = alkali, B = metal, Z = chalcogen) NCs as tunable platforms for advanced functional applications.}, author = {Patil, Niraj Nitish and Wu, Ruiqi and Fiedler, Christine and Kapuria, Nilotpal and Nan, Bingfei and Navita, Navita and Cabot, Andreu and Ibáñez, Maria and Ryan, Kevin M. and Ganose, Alex M. and Singh, Shalini}, issn = {2380-8195}, journal = {ACS Energy Letters}, number = {1}, pages = {481--488}, publisher = {American Chemical Society}, title = {{Layered alkali-copper selenides: Deciphering thermoelectric properties and reaction pathways for nanostructuring β-CsCu5Se3}}, doi = {10.1021/acsenergylett.5c02909}, volume = {11}, year = {2026}, } @article{21002, abstract = {The Davenport–Heilbronn method is a version of the circle method that was developed for studying Diophantine inequalities in the paper (Davenport and Heilbronn, J. Lond. Math. Soc. (1) 21 (1946), 185–193). We discuss the main ideas in the paper, together with an account of the development of the subject in the intervening 80 years.}, author = {Browning, Timothy D}, issn = {1469-7750}, journal = {Journal of the London Mathematical Society}, number = {1}, publisher = {Wiley}, title = {{The Davenport–Heilbronn method: 80 years on}}, doi = {10.1112/jlms.70371}, volume = {113}, year = {2026}, } @article{21008, abstract = {C(sp2)–heteroatom couplings operating via NiI/NiIII catalysis have emerged as an alternative to canonical Pd0/PdII systems that require complex ligand architectures. Despite intensive research efforts during the past decade, catalytic methods employing this approach are still mostly confined to activated starting materials and require high catalyst loadings due to the low catalytic activity of NiI and undesired catalyst deactivation events. This article highlights recent advances in the field toward solving these long-standing challenges. We survey strategies that streamline the generation of catalytically competent NiI species from bench-stable NiII precatalysts, and discuss mechanistic studies that shed light on deactivation pathways and the rate-determining oxidative addition of aryl halides. In the final section, we highlight recently developed synthetic methodologies, which provide evidence that limitations can indeed be addressed by working at elevated temperatures, employing alternative electrophiles, harnessing the benefits of additives, or fine-tuning the metal’s reactivity through the ligand field.}, author = {Bena, Aleksander and Pieber, Bartholomäus}, issn = {2155-5435}, journal = {ACS Catalysis}, number = {2}, pages = {866--881}, publisher = {American Chemical Society}, title = {{Advances in NiI/NiIII-catalyzed C(sp2)–heteroatom cross-couplings}}, doi = {10.1021/acscatal.5c07964}, volume = {16}, year = {2026}, } @article{21012, abstract = {In certifiable machine learning, AI systems produce not only results but also verifiable certificates that the results can be trusted.}, author = {Barrett, Clark and Henzinger, Thomas A and Seshia, Sanjit A.}, issn = {1557-7317}, journal = {Communications of the ACM}, number = {1}, pages = {66--75}, publisher = {Association for Computing Machinery}, title = {{Certificates in AI: Learn but verify}}, doi = {10.1145/3737447}, volume = {69}, year = {2026}, } @article{21013, abstract = {We have addressed convective self‐aggregation (CSA) in steady and oscillating sea surface temperature (SST) and solar radiation (SOLIN) cloud‐resolving model simulations in a non‐rotating radiative‐convective equilibrium (RCE) framework. Our experiment designs are motivated by land‐ocean heterogeneity of atmospheric convection. The steady and oscillating forcings are idealizations of ocean and land conditions, respectively, based on their differences in heat capacities. In both kinds of simulations, the diurnal mean SST and SOLIN are the same, and both SST and SOLIN are only varied in time (i.e., they are spatially homogeneous at any given time). We find that diurnally oscillating forcing accelerates CSA. Stronger long‐wave cooling in dry regions at night and during the warm SST phase (late afternoon) both allow the long‐wave feedback, known to favor aggregation, to intensify compared to steady forcing simulations. In addition to the long‐wave, reduced short‐wave warming in dry regions (during the day) further enhances radiative cooling there compared to moist regions. Overall, the radiative cooling is enhanced in dry regions compared to neighboring moist convective regions. A dry subsidence is driven by this net radiative (short‐wave plus long‐wave) cooling, consistent with earlier work on CSA. Stronger radiative cooling allows stronger subsidence which allows low‐level circulation to more efficiently transport moisture and energy up‐gradient, driving convection to aggregate faster. We also note a sensitivity of our experimental setup to initial conditions, more so at warmer SST. This stochastic behavior might be critical in reconciling the differences of opinion regarding the response of convection aggregation to oscillating SST forcing.}, author = {GOSWAMI, BIDYUT B and Lu, Ziyin and Muller, Caroline J}, issn = {1942-2466}, journal = {Journal of Advances in Modeling Earth Systems}, number = {1}, publisher = {Wiley}, title = {{Convective self‐aggregation in diurnally oscillating sea surface temperature and solar forcing experiments}}, doi = {10.1029/2024ms004576}, volume = {18}, year = {2026}, } @article{21018, abstract = {In this paper, we review recent results on stability and instability in logarithmic Sobolev inequalities, with a particular emphasis on strong norms. We consider several versions of these inequalities on the Euclidean space, for the Lebesgue and the Gaussian measures, and discuss their differences in terms of moments and stability. We give new and direct proofs, as well as examples and discuss the stability of a logarithmic uncertainty principle. Although we do not cover all aspects of the topic, we hope to contribute to establishing the state of the art.}, author = {Brigati, Giovanni and Dolbeault, Jean and Simonov, Nikita}, issn = {2730-9657}, journal = {La Matematica}, publisher = {Springer Nature}, title = {{Logarithmic Sobolev Inequalities: A review on stability and instability results}}, doi = {10.1007/s44007-025-00180-y}, volume = {5}, year = {2026}, } @article{21035, abstract = {According to the scientific consensus, tropical convection must decrease with global warming. This decrease is manifested by a decrease of the mass transported in the upward branch of the atmospheric overturning circulation – the convective mass flux – and a connected decrease of high clouds in the tropics, with implications for climate sensitivity. By using kilometer-scale simulations in radiative-convective equilibrium and a convective tracking algorithm, we show that no such decrease occurs in storms when taken individually and that the mass transport per storm increases instead. Storms can achieve this result by aggregating more surface of the convective cores – the inner part of the storm doing the vertical transport – so that the decrease of tropical convection is actually explained by a decrease in the total number of storms. There is little variation of the mean pressure velocity in the cores of the storms, a robust finding of this study. This remarkable invariance of the mean pressure velocity points to an emerging property of convection that should receive more attention in future studies.}, author = {Bolot, Maximilien and Roca, Rémy and Fiolleau, Thomas and Muller, Caroline J}, issn = {2397-3722}, journal = {npj Climate and Atmospheric Science}, publisher = {Springer Nature}, title = {{No decrease of tropical convection in individual deep convective systems with global warming}}, doi = {10.1038/s41612-025-01285-5}, volume = {9}, year = {2026}, } @article{21036, abstract = {Forests under livestock grazing sustain important ecosystem services but face potential trade-offs between production and ecological integrity. While the effects of grazing on individual forest attributes are well documented, their integrated consequences remain poorly understood, particularly in temperate forest ecosystems. We evaluated the combined influence of livestock grazing intensity and canopy cover on individual attributes and ecosystem multifunctionality in native Nothofagus forests of Tierra del Fuego, Argentina. Across eight ranches spanning two agroecological regions (Ecotone and Mountain Range), we quantified forest regeneration, understorey richness and biomass, and soil properties, integrating them into a multifunctionality index. Using generalized linear mixed models, we found strong context-dependence: in the Mountain Range, higher grazing intensity reduced seedling and sapling density, organic matter content, coarse woody debris, and overall multifunctionality. In the Ecotone, these effects of livestock use intensity were attenuated, and canopy cover diminished sapling density and multifunctionality, but moderate cover enhanced understorey. Our results extend multifunctionality research from grazed grasslands to grazed temperate forests and show that ecological responses and trade-offs vary across landscape units. We conclude that the Mountain Range is more vulnerable to grazing, requiring stricter management, whereas the Ecotone retains greater capacity to sustain multifunctionality under controlled livestock use intensity. These findings underscore the importance of region-specific silvopastoral strategies that reconcile food production with forest conservation in southern Patagonia and comparable temperate forest landscapes worldwide.}, author = {Rodríguez, Paula and Cruz Alonso, Verónica and Romano, Silvina and Bustamante, Gimena and Soler Schaller, Rosina Matilde}, issn = {0167-8809}, journal = {Agriculture, Ecosystems and Environment}, publisher = {Elsevier}, title = {{Context-dependent effects of livestock grazing on forest attributes and ecosystem multifunctionality in Nothofagus forests}}, doi = {10.1016/j.agee.2026.110219}, volume = {400}, year = {2026}, } @article{21037, abstract = {The oxygen reduction reaction (ORR) remains a critical bottleneck in fuel cells and metal-air batteries due to the lack of highly efficient electrocatalysts. Here, we report a simple strategy for synthesizing a palladium-based heterostructured electrocatalyst supported on a carbon nitride matrix (PdH-Pd@CN), which exhibits remarkable ORR activity with a half-wave potential of 0.91 V and excellent durability in 0.1 M KOH. Within the heterostructure, hydrogen intercalation expands the Pd lattice, while interstitial hydrogen doping facilitates charge transfer from Pd to H owing to their electronegativity difference. These synergistic effects modulate the electronic structure, thereby enhancing both activity and stability. When employed in Zn-air batteries, PdH-Pd@CN delivers a maximum power density of 176 mW cm− (Liu et al., 2025) and capacity of 805 mAh g− (Sun et al., 2021) Zn. These findings demonstrate the strong potential of PdH-Pd@CN as an efficient ORR electrocatalyst for next-generation metal-air batteries and related energy technologies.}, author = {Shi, Changwei and Horta, Sharona and Ibáñez, Maria and Kallio, Tanja and Martínez-Alanis, Paulina R. and Wang, Xiang and Cabot, Andreu}, issn = {0009-2509}, journal = {Chemical Engineering Science}, publisher = {Elsevier}, title = {{Hydrogen induced palladium-based heterojunction electrocatalysts to enhance the oxygen reduction reaction performance}}, doi = {10.1016/j.ces.2026.123348}, volume = {324}, year = {2026}, } @article{21038, abstract = {Little Red Dots (LRDs) are compact sources at z > 5 discovered through James Webb Space Telescope spectroscopy. Their spectra exhibit broad Balmer emission lines (>~1000 km s^−1), alongside absorption features and a pronounced Balmer break – evidence for a dense, neutral hydrogen medium, in which the n = 2 state is significantly populated. When interpreted as arising from active galactic nucleus broad-line regions, inferred black hole masses from local scaling relations exceed expectations given their stellar masses, challenging models of early black hole–galaxy co-evolution. However, radiative transfer effects in dense media may also impact the formation of hydrogen emission lines. We model three scattering processes shaping hydrogen line profiles: resonance scattering by hydrogen in the n = 2 state, Raman scattering of ultraviolet (UV) radiation by ground-state hydrogen, and Thomson scattering by free electrons. Using 3D Monte Carlo radiative transfer simulations, we examine their imprint on line shapes and ratios. Resonance scattering produces strong deviations from Case B flux ratios, clear differences between Hα and Hβ, and encodes gas kinematics in line profiles but cannot broaden Hβ due to conversion to Paα. While Raman scattering can yield broad wings, scattering of the UV continuum is disfavoured given the absence of strong full width at half-maximum variations across transitions. Raman scattering of higher Lyman-series emission can produce Hα/Hβ wing width ratios of >~1.28, agreeing with observations. Thomson scattering can reproduce the observed >~ 1000 km s^−1 wings under plausible conditions – e.g. Te ∼ 10^4 K and Ne ∼ 10^24 cm^−2 – and lead to black hole mass overestimates by factors 10. Our results provide a framework for interpreting hydrogen lines in LRDs and similar systems.}, author = {Chang, Seok Jun and Gronke, Max and Matthee, Jorryt J and Mason, Charlotte}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {4}, publisher = {Oxford University Press}, title = {{Impact of resonance, Raman, and Thomson scattering on hydrogen line formation in Little Red Dots}}, doi = {10.1093/mnras/staf2131}, volume = {545}, year = {2026}, } @article{21039, abstract = {Cellular plasticity, the ability of a differentiated cell to adopt another phenotypic identity, is restricted under basal conditions, but can be elicited upon damage. However, the molecular mechanism enabling such plasticity remains largely unexplored. Here, we report damage-induced cellular plasticity of secretory enteroendocrine cells (EEs) in the adult Drosophila midgut. Ionizing radiation induces EE fate conversion and activates stress-responsive programs in EE lineages, accompanied by the induction of the stress-inducible transcription factor Xrp1 and the cytokine gene upd3. Xrp1 and upd3 are both necessary for radiation-induced EE plasticity. Under basal conditions, EE-specific Xrp1 overexpression triggers ectopic expression of progenitor-specific genes, which is necessary for Xrp1 to drive EE plasticity. Our work identifies Xrp1 as a crucial regulator that coordinates damage-induced signaling and transcriptional reprogramming, enabling the reactivation of cellular plasticity in differentiated cells.}, author = {Qian, Qingyin and Nagai, Hiroki and Sanaki, Yuya and Hayashi, Makoto and Kimura, Kenichi and Nakajima, Yu Ichiro and Niwa, Ryusuke}, issn = {1477-9129}, journal = {Development}, number = {2}, publisher = {The Company of Biologists}, title = {{Xrp1 drives damage-induced cellular plasticity of enteroendocrine cells in the adult Drosophila midgut}}, doi = {10.1242/dev.205225}, volume = {153}, year = {2026}, } @article{21040, abstract = {Formation during the first cycles of Li-rich layered oxide (LRLO) cathode materials consolidates the interphase and leads to structural changes that are decisive for long-term cyclability. However, the nature and effect of the changes are material-dependent and unknown for the important class of Co-free, Ni-poor LRLOs. Here, we analyze the processes during the tailored formation procedure of a typical class member, Li1.28Ni0.15Mn0.57O2, and demonstrate that it remarkably changes lattice composition and structure as a prerequisite for stable cycling. We combine electrochemistry, operando mass spectrometry, X-ray diffraction, and X-ray absorption spectroscopy with density functional theory simulations. Activation most prominently compresses the layer spacing along the c-axis and increases reversible structural breathing. The large capacity of ∼250 mAh g–1 originates from the Ni2+/Ni4+ and O2–/O– redox couples. Electron exchange during O-redox is smeared over the entire anionic sublattice rather than localized on specific oxygen atomic sites. This redox mechanism is reversible without detrimental oxygen evolution, avoiding continued degradation common in conventional LRLOs. Sequential Ni- and O-redox during activation irreversibly distorts the coordination of the redox-inactive Mn4+ centers. This structural evolution of the MnO6 octahedra appears to enable the superior electrochemical performance of this LRLO phase. These findings define an activation pathway for the important class of Co-free, Ni-poor LRLOs, offering potential guidance for the rational design of high-performance, more sustainable cathode materials.}, author = {Busato, Matteo and Tuccillo, Mariarosaria and Celeste, Arcangelo and Tofoni, Alessandro and Silvestri, Laura and D’Angelo, Paola and Freunberger, Stefan Alexander and Brutti, Sergio}, issn = {2574-0962}, journal = {ACS Applied Energy Materials}, number = {1}, pages = {686--697}, publisher = {American Chemical Society}, title = {{Structural rearrangements of a Cobalt-free Lithium-rich layered oxide cathode during formation}}, doi = {10.1021/acsaem.5c03511}, volume = {9}, year = {2026}, } @article{21041, abstract = {It is common for programmers to assemble their programs from a combination of trusted and untrusted components. In this context, a trusted program component is said to be robustly safe if it behaves safely when linked against arbitrary untrusted code. Prior work has shown how various encapsulation mechanisms (in both high- and low-level languages) can be used to protect code so that it is robustly safe, but none of the existing work has explored how robust safety can be achieved in a patently unsafe language like C. In this paper, we show how to bring robust safety to a simple yet representative C-like language we call Rec. Although Rec (like C) is inherently ”dangerous” and thus not robustly safe, we can ”save” Rec programs via compilation to Cap, a CHERI-like capability machine. To formalize the benefits of such a hardening compiler, we develop Reckon, a separation logic for verifying robust safety of Rec programs. Reckon is not sound under Rec’s unsafe, C-like semantics, but it is sound when Rec programs are hardened via compilation and linked against untrusted code running on Cap. As a crucial step in proving soundness of Reckon, we introduce a novel technique of semantic back-translation, which we formalize by building on the DimSum framework for multi-language semantics. All our results are mechanized in the Rocq prover.}, author = {Mück, Niklas and Georges, Aïna Linn and Dreyer, Derek and Garg, Deepak and Sammler, Michael Joachim}, issn = {2475-1421}, journal = {Proceedings of the ACM on Programming Languages}, pages = {1153--1182}, publisher = {Association for Computing Machinery}, title = {{Endangered by the language but saved by the compiler: Robust safety via semantic back-translation}}, doi = {10.1145/3776682}, volume = {10}, year = {2026}, } @inproceedings{21042, abstract = {Many blockchains such as Ethereum execute all incoming transactions sequentially significantly limiting the potential throughput. A common approach to scale execution is parallel execution engines that fully utilize modern multi-core architectures. Parallel execution is then either done optimistically, by executing transactions in parallel and detecting conflicts on the fly, or guided, by requiring exhaustive client transaction hints and scheduling transactions accordingly. However, recent studies have shown that the performance of parallel execution engines depends on the nature of the underlying workload. In fact, in some cases, only a 60% speed-up compared to sequential execution could be obtained. This is the case, as transactions that access the same resources must be executed sequentially. For example, if 10% of the transactions in a block access the same resource, the execution cannot meaningfully scale beyond 10 cores. Therefore, a single popular application can bottleneck the execution and limit the potential throughput. In this paper, we introduce Anthemius, a block construction algorithm that optimizes parallel transaction execution throughput. We evaluate Anthemius exhaustively under a range of workloads, and show that Anthemius enables the underlying parallel execution engine to process over twice as many transactions.}, author = {Neiheiser, Ray and Kokoris Kogias, Eleftherios}, booktitle = {29th International Conference on Financial Cryptography and Data Security}, isbn = {9783032070234}, issn = {1611-3349}, location = {Miyakojima, Japan}, pages = {307--323}, publisher = {Springer Nature}, title = {{Anthemius: Efficient and modular block assembly for concurrent execution}}, doi = {10.1007/978-3-032-07024-1_18}, volume = {15751}, year = {2026}, } @article{21045, abstract = {The abundant population of little red dots (LRDs), compact objects with red UV to optical colors and broad Balmer lines at high redshift, is revealing new insights into the properties of early active galactic nuclei (AGN). Perhaps the most surprising features of this population are the presence of Balmer absorption and ubiquitous strong Balmer breaks. Recent models link these features to an active supermassive black hole (SMBH) cocooned in very dense gas (NH ∼ 1024 cm−2). We present a stringent test of such models using VLT/MUSE observations of A2744-45924, the most luminous LRD known to date (LHα ≈ 1044 erg s−1), located behind the Abell-2744 lensing cluster at z = 4.464 (μ = 1.8). We detect a moderately extended Lyα nebula (h ≈ 5.7 pkpc), spatially offset from the point-like Hα seen by JWST by ≈1.6 pkpc. The Lyα emission is narrow (FWHM = 270 ± 15 km s−1), and faint (Lyα = 0.07Hα) compared to Lyα nebulae typically observed around quasars of similar luminosity. We detect compact N IV]λ1486 emission, spatially aligned with Hα, and a spatial shift in the far-UV continuum matching the Lyα offset. We discuss that Hα and Lyα have distinct physical origins: Hα originates from the AGN, while Lyα is powered by star formation. In the environment of A2744-45924, we identified four extended Lyα halos (Δz < 0.02, Δr < 100 pkpc). Their Lyα luminosities match the expectations based on Hα emission, and show no evidence for radiation from A2744-45924 affecting its surroundings. The lack of strong, compact, and broad Lyα and the absence of a luminous extended halo, suggest that the UV AGN light is obscured by dense gas cloaking the SMBH with a covering factor close to unity.}, author = {Torralba Torregrosa, Alberto and Matthee, Jorryt J and Pezzulli, Gabriele and Urrutia, Tanya and Gronke, Max and Mascia, Sara and D’Eugenio, Francesco and Di Cesare, Claudia and Eilers, Anna Christina and Greene, Jenny E. and Iani, Edoardo and Ishikawa, Yuzo and Mackenzie, Ruari and Naidu, Rohan P. and Navarrete, Benjamín and Kotiwale, Gauri}, issn = {1432-0746}, journal = {Astronomy and Astrophysics}, publisher = {EDP Sciences}, title = {{A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded supermassive black hole growth}}, doi = {10.1051/0004-6361/202555596}, volume = {705}, year = {2026}, } @inbook{21056, abstract = {In 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^𝑡⁢ℎ-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 tracks 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: 1. Monodromy of any periodicity can occur in a 𝑙-vineyard for any 𝑙. This answers a variant of a question by Arya and collaborators. 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. 2. Topologically distinguishing closed vineyards is likely to be difficult (from a complexity theory as well as from a practical perspective) because of the difficulty of knot and link recognition, which have strong connections to many NP-hard problems.}, author = {Chambers, Erin W. and Fillmore, Christopher D and Stephenson, Elizabeth R and Wintraecken, Mathijs}, booktitle = {Proceedings of the 2026 Annual ACM-SIAM Symposium on Discrete Algorithms}, editor = {Green Larsen, Kasper and Saha, Barna}, pages = {6240--6263}, publisher = {Society for Industrial and Applied Mathematics}, title = {{Braiding Vineyards}}, doi = {10.1137/1.9781611978971.225}, year = {2026}, } @inproceedings{21113, abstract = {Causal discovery from i.i.d. observational data is known to be generally ill-posed. We demonstrate that if we have access to the distribution induced by a structural causal model, and additional data from (in the best case) only two environments that sufficiently differ in the noise statistics, the unique causal graph is identifiable. Notably, this is the first result in the literature that guarantees the entire causal graph recovery with a constant number of environments and arbitrary nonlinear mechanisms. Our only constraint is the Gaussianity of the noise terms; however, we propose potential ways to relax this requirement. Of interest on its own, we expand on the well-known duality between independent component analysis (ICA) and causal discovery; recent advancements have shown that nonlinear ICA can be solved from multiple environments, at least as many as the number of sources: we show that the same can be achieved for causal discovery while having access to much less auxiliary information.}, author = {Montagna, Francesco}, booktitle = {The 14th International Conference on Learning Representations}, location = {Rio de Janeiro, Brazil}, publisher = {OpenReview}, title = {{On the identifiability of causal graphs with multiple environments}}, year = {2026}, } @article{21115, abstract = {Quantifying cell morphology is central to understanding cellular regulation, fate, and heterogeneity, yet conventional image-based analyses often struggle with diverse or irregular shapes. We present a computational framework that uses topological data analysis to characterise and compare single-cell morphologies from fluorescence microscopy. Each cell is represented by its contour together with the position of its nucleus, from which we construct a filtration based on a radial distance function and derive a persistence diagram encoding the shape’s topological evolution. The similarity between two cells is quantified using the 2-Wasserstein distance between their diagrams, yielding a shape distance we call the PH distance. We apply this method to two representative experimental systems—primary human mesenchymal stem cells (hMSCs) and HeLa cells—and show that PH distances enable the detection of outliers in those systems, the identification of sub-populations, and the quantification of shape heterogeneity. We benchmark PH against three established contour-based distances (aspect ratio, Fourier descriptors, and elastic shape analysis) and show that PH offers better separation between cell types and greater robustness when clustering heterogeneous populations. Together, these results demonstrate that persistent-homology-based signatures provide a principled and sensitive approach for analysing cell morphology in settings where traditional geometric or image-based descriptors are insufficient.}, author = {Bleile, Yossi and Yadav, Pooja and Koehl, Patrice and Rehfeldt, Florian}, issn = {1553-7358}, journal = {PLoS Computational Biology}, publisher = {Public Library of Science}, title = {{Persistence diagrams as morphological signatures of cells: A method to measure and compare cells within a population}}, doi = {10.1371/journal.pcbi.1013890}, volume = {22}, year = {2026}, }