@article{20192, abstract = {We study the physical origin and spectroscopic impact of extreme nebular emission in high-redshift galaxies. The nebular continuum, which can appear during an extreme starburst, is of particular importance as it tends to redden UV slopes and has a significant contribution to the UV luminosities of galaxies. Furthermore, its shape can be used to infer the gas density and temperature of the interstellar medium. First, we provide a theoretical background, showing how different stellar populations (SPS models, initial mass functions (IMFs), and stellar temperatures) and nebular conditions impact observed galaxy spectra. We demonstrate that, for systems with strong nebular continuum emission, 1) UV fluxes can increase by up to 0.7~mag (or more in the case of hot/massive stars) above the stellar continuum, which may help reconcile the surprising abundance of bright high-redshift galaxies and the elevated UV luminosity density at z>10, 2) at high gas densities, UV slopes can redden from \beta<-2.5 to \beta\sim-1, 3) observational measurements of \xi_{\rm ion} are gross underestimates, and 4) UV downturns from two-photon emission can masquerade as damped Ly\alpha systems. Second, we present a dataset of 58 galaxies observed with NIRSpec on JWST at 2.510 galaxies, finding that UV slopes and UV downturns are in some cases redder or steeper than expected from SPS models, which may hint at more exotic (e.g. hotter/more massive stars or AGN) ionizing sources.}, author = {Katz, Harley and Cameron, Alex J. and Saxena, Aayush and Barrufet, Laia and Choustikov, Nicholas and Cleri, Nikko J. and De Graaff, Anna and Ellis, Richard S. and Fosbury, Robert A.E. and Heintz, Kasper E. and Maseda, Michael and Matthee, Jorryt J and Mcconachie, Ian and Oesch, Pascal A.}, issn = {2565-6120}, journal = {The Open Journal of Astrophysics}, publisher = {Maynooth Academic Publishing}, title = {{21 Balmer Jump Street: The nebular continuum at high redshift and implications for the bright galaxy problem, UV continuum slopes, and early stellar populations}}, doi = {10.33232/001c.142570}, volume = {8}, year = {2025}, } @article{20193, abstract = {Understanding the rapid formation of supermassive black holes in the early Universe requires insights into stellar mass growth in host galaxies. Here we present NIRSpec rest-frame optical spectra and NIRCam imaging from JWST of two galaxies at z > 6, both hosting moderate-luminosity quasars. These galaxies exhibit Balmer absorption lines, like low-redshift post-starburst galaxies. Our analyses of the medium-resolution spectra and multiband photometry show that the bulk of the stellar mass (log(M*/M☉) ≥ 10.6) formed in starburst episodes at redshift 9 and 7. One of the galaxies shows a clear Balmer break and lacks spatially resolved Hα emission. It falls well below the star-formation main sequence at z = 6, indicating quiescence. The other is transitioning to quiescence; together, these massive galaxies are among the most distant post-starburst systems known. The blueshifted wings of the quasar [O iii] emission lines indicate quasar-driven outflow, which possibly influences star formation. Direct stellar velocity dispersion measurements reveal that one galaxy follows the local black hole mass versus σ* relation whereas the other is overmassive. The existence of massive post-starburst galaxies hosting billion-solar-mass black holes in short-lived quasar phases indicates that supermassive black holes and host galaxies played a principal role in each other’s rapid early formation.}, author = {Onoue, Masafusa and Ding, Xuheng and Silverman, John D. and Matsuoka, Yoshiki and Izumi, Takuma and Strauss, Michael A. and Ward, Charlotte and Phillips, Camryn L. and Ito, Kei and Andika, Irham T. and Aoki, Kentaro and Arita, Junya and Baba, Shunsuke and Bieri, Rebekka and Bosman, Sarah E.I. and Eilers, Anna Christina and Fujimoto, Seiji and Habouzit, Melanie and Haiman, Zoltán and Imanishi, Masatoshi and Inayoshi, Kohei and Iwasawa, Kazushi and Jahnke, Knud and Kashikawa, Nobunari and Kawaguchi, Toshihiro and Kohno, Kotaro and Lee, Chien Hsiu and Li, Junyao and Lupi, Alessandro and Lyu, Jianwei and Nagao, Tohru and Overzier, Roderik and Schindler, Jan Torge and Schramm, Malte and Scoggins, Matthew T. and Shimasaku, Kazuhiro and Toba, Yoshiki and Trakhtenbrot, Benny and Trebitsch, Maxime and Treu, Tommaso and Umehata, Hideki and Venemans, Bram and Vestergaard, Marianne and Volonteri, Marta and Walter, Fabian and Wang, Feige and Yang, Jinyi and Zhang, Haowen}, issn = {2397-3366}, journal = {Nature Astronomy}, pages = {1541--1552}, publisher = {Springer Nature}, title = {{A post-starburst pathway for the formation of massive galaxies and black holes at z > 6}}, doi = {10.1038/s41550-025-02628-1}, volume = {9}, year = {2025}, } @phdthesis{20203, abstract = {Tribocharging, or contact electrification, is the phenomenon in which two initially neutral materials exchange electric charge through contact and subsequent separation. While it is widely observed in everyday life and crucial to numerous natural processes, even the most basic aspects of tribocharging are still a mystery—what are the charge carriers involved and what drives their exchange? This work spans three separate projects that address different aspects of tribocharging. First, we introduce a novel strategy combining Finite Element Method (FEM) simulations with Kelvin Probe Force Microscopy (KPFM) to quantitatively extract surface charge density from surface voltage maps. Second, we present a simple theoretical model that allows for the existence of triboelectric cycles, under the assumption that multiple charge carrying species are involved. Third, we present experimental evidence that identical materials can spontaneously evolve into a triboelectric series, driven by contact history. Modeling this behavior enables the replication of experimental results with simulations, and even experimentally forcing the appearance of a pre-designed series by manipulating contact history. Together, the findings from these projects challenge traditional views on tribocharging, provide new tools for probing it, and open up new avenues of research—all with the hopes of bringing us closer to understanding this puzzling phenomenon.}, author = {Sobarzo Ponce, Juan Carlos A}, isbn = {978-3-99078-062-6}, issn = {2663-337X}, pages = {96}, publisher = {Institute of Science and Technology Austria}, title = {{Tribocharging of identical insulators : Triboelectric series, triboelectric cycles and surface charges}}, doi = {10.15479/AT-ISTA-20203}, year = {2025}, } @phdthesis{20206, abstract = {The internal structure of biomolecules and their organization in higher-order arrangements are key factors governing the working principles of biological systems. Bioimaging has successfully revealed arrangements across relevant spatial scales. For example, cryo-electron tomography has become widely used for analyzing biomolecular structures in situ due to its comprehensive structural visualization of near-natively preserved samples, and its capability of sub-nm resolution via averaging. However, the identification of molecules within crowded cellular environments is often hindered by low contrast. Fluorescence microscopy, on the other hand, routinely visualizes specifically labeled targets at single-molecule contrast against essentially zero background. Moreover, it provides comparatively high throughput and is amenable to multiplexing. Due to this complementarity, combining datasets from both modalities acquired on the same region via correlative light and electron microscopy can reveal novel types of information. The spatial scale at which information can be extracted depends on imaging resolution and correlation accuracy. Since diffraction of light limits the resolution of conventional fluorescence microscopy to few hundreds of nanometers, reaching the full potential of correlative imaging requires super-resolution approaches. Performing imaging at cryogenic temperature preserves structures in a near-native state and minimizes distortions between the fluorescence and the electron microscopy datasets. Implementations of this concept have achieved correlation on the scale of cellular organelles or bacterial domains. We have worked towards pushing correlative imaging to the single-molecule scale by improving cryo-super-resolution microscopy, and devising a refined image correlation workflow. As part of this project, I constructed a microscopy setup and adopted it for super-resolution fluorescence microscopy at room temperature and cryogenic conditions. I explored different cryo-stages and acquisition strategies. Specifically, I developed a new scheme for correcting sample drift, thus increasing mechanical stability during microscopy acquisitions. }, author = {Vorlaufer, Jakob}, issn = {2663-337X}, pages = {107}, publisher = {Institute of Science and Technology Austria}, title = {{Construction of a cryo-super-resolution microscope to guide in situ structure analysis}}, doi = {10.15479/AT-ISTA-20206}, year = {2025}, } @phdthesis{20212, author = {Miranda, Osvaldo}, isbn = {978-3-99078-063-3}, issn = {2663-337X}, keywords = {Pten, mtor, cortical development, MADM, Mapk}, pages = {119}, publisher = {Institute of Science and Technology Austria}, title = {{Unraveling the role of Pten in cortical stem cell lineage progression using MADM}}, doi = {10.15479/AT-ISTA-20212}, year = {2025}, } @article{20217, abstract = {We present Virgil, a Mid-Infrared Instrument (MIRI) extremely red object detected with the F1000W filter as part of the MIRI Deep Imaging Survey observations of the Hubble Ultra Deep Field. Virgil is an Lyα emitter (LAE) at zspec = 6.6312 ± 0.0019 (from the Very Large Telescope/MUSE) with a rest-frame UV-to-optical spectral energy distribution (SED) typical of LAEs at similar redshifts. However, MIRI observations reveal an unexpected extremely red color at rest-frame near-infrared (NIR) wavelengths, F444W − F1000W = 2.33 ± 0.06. Such a steep rise in the NIR, completely missed without MIRI imaging, is poorly reproduced by models including only stellar populations and hints toward the presence of an active galactic nucleus, although alternative explanations such as extreme dust obscuration and strong nebular continuum and emission lines contribution due to young stellar ages cannot be completely ruled out. According to the shape of its overall SED, Virgil belongs to the recently discovered population of little red dots but displays an extended rest-frame UV-optical wavelength morphology following a 2DSérsic profile with an average index of n = 0.93+0.85_0.31 and re = 0.49+0.05_0.11 pkpc. Only at MIRI wavelengths, Virgil is unresolved due to the coarser point-spread function. This discovery demonstrates the crucial importance of deep MIRI surveys to reveal the true nature and properties of high-z galaxies that otherwise would be misinterpreted and raises the question of how common Virgil-like objects could be in the early Universe.}, author = {Iani, Edoardo and Rinaldi, Pierluigi and Caputi, Karina I. and Annunziatella, Marianna and Langeroodi, Danial and Melinder, Jens and Pérez-González, Pablo G. and Álvarez-Márquez, Javier and Boogaard, Leindert A. and Bosman, Sarah E.I. and Costantin, Luca and Moutard, Thibaud and Colina, Luis and Östlin, Göran and Greve, Thomas R. and Wright, Gillian and Alonso-Herrero, Almudena and Bik, Arjan and Gillman, Steven and Crespo Gómez, Alejandro and Hjorth, Jens and Kendrew, Sarah and Labiano, Alvaro and Pye, John P. and Tikkanen, Tuomo V. and Walter, Fabian and Güdel, Manuel and Henning, Thomas and Van Der Werf, Paul P.}, issn = {1538-4357}, journal = {The Astrophysical Journal}, number = {2}, publisher = {IOP Publishing}, title = {{MIDIS: MIRI uncovers Virgil, the first Little Red Dot with clear detection of its host galaxy at z ≃ 6.6}}, doi = {10.3847/1538-4357/ade5a6}, volume = {989}, year = {2025}, } @article{20218, abstract = {Humanity has long sought inspiration from nature to innovate materials and devices. As science advances, nature-inspired materials are becoming part of our lives. Animate materials, characterized by their activity, adaptability, and autonomy, emulate properties of living systems. While only biological materials fully embody these principles, artificial versions are advancing rapidly, promising transformative impacts in the circular economy, health and climate resilience within a generation. This roadmap presents authoritative perspectives on animate materials across different disciplines and scales, highlighting their interdisciplinary nature and potential applications in diverse fields including nanotechnology, robotics and the built environment. It underscores the need for concerted efforts to address shared challenges such as complexity management, scalability, evolvability, interdisciplinary collaboration, and ethical and environmental considerations. The framework defined by classifying materials based on their level of animacy can guide this emerging field to encourage cooperation and responsible development. By unravelling the mysteries of living matter and leveraging its principles, we can design materials and systems that will transform our world in a more sustainable manner.}, author = {Volpe, Giorgio and Araújo, Nuno A.M. and Guix, Maria and Miodownik, Mark and Martin, Nicolas and Alvarez, Laura and Simmchen, Juliane and Leonardo, Roberto Di and Pellicciotta, Nicola and Martinet, Quentin and Palacci, Jérémie A and Ng, Wai Kit and Saxena, Dhruv and Sapienza, Riccardo and Nadine, Sara and Mano, João F. and Mahdavi, Reza and Beck Adiels, Caroline and Forth, Joe and Santangelo, Christian and Palagi, Stefano and Seok, Ji Min and Webster-Wood, Victoria A. and Wang, Shuhong and Yao, Lining and Aghakhani, Amirreza and Barois, Thomas and Kellay, Hamid and Coulais, Corentin and Van Hecke, Martin and Pierce, Christopher J. and Wang, Tianyu and Chong, Baxi and Goldman, Daniel I. and Reina, Andreagiovanni and Trianni, Vito and Volpe, Giovanni and Beckett, Richard and Nair, Sean P. and Armstrong, Rachel}, issn = {1361-648X}, journal = {Journal of Physics Condensed Matter}, number = {33}, publisher = {IOP Publishing}, title = {{Roadmap for animate matter}}, doi = {10.1088/1361-648X/adebd3}, volume = {37}, year = {2025}, } @article{20219, abstract = {Reproduction is a fundamental biological process, with organisms reproducing sexually, asexually, and, in some cases, utilizing both modes of reproduction within the same population. Does the ability to reproduce through a combination of asexual and sexual modes offer an evolutionary advantage over relying on either mode alone? Here, we introduce an empirically driven theoretical model to examine the dynamics and interplay between sexual and asexual reproduction in stick insect populations. We analyse it using a novel phase transition approach and corroborate it using published experimental data. We find that the presence of males can either increase or decrease the overall population size. However, maintaining an optimal ratio of parthenogenetic to sexual reproduction is crucial for male resilience, effectively delaying male extinction. Conversely, extreme levels of parthenogenetic reproduction—whether too high or too low—can lead to male extinction, emphasizing the need for a balanced number of virgin females to ensure the persistence of males. Our model also explains male absence in Carausius morosus and persistence in Extatosoma tiaratum. Our findings provide valuable insights into the interplay of reproductive strategies and contribute to broader discussions on the transitions between sexual and asexual reproduction.}, author = {Ayalon, Oran and Rajendran, Harikrishnan}, issn = {1742-5662}, journal = {Journal of the Royal Society Interface}, number = {229}, publisher = {The Royal Society}, title = {{Interplay of asexual and sexual reproduction in bifunctional insects}}, doi = {10.1098/rsif.2025.0202}, volume = {22}, year = {2025}, } @article{20220, abstract = {Stress granules (SG) are biomolecular condensates that represent an adaptive response of cells to various stresses, including heat. However, the cell type–specific function and relevance of SG formation, especially during reproductive development, are largely not understood. Here, we show that the meiotic A-type cyclin TARDY ASYNCHRONOUS MEIOSIS (TAM) is recruited to SGs in male meiocytes of Arabidopsis after exposure to heat. We find that the amino terminus of TAM is necessary and sufficient for the localization of proteins to meiotic SGs. Swapping the amino terminus of TAM with the one of its sister protein CYCA1;1 resulted in a separation-of-function allele of TAM, which prevents the partitioning of TAM to SGs while restoring a wild-type phenotype in a tam mutant background under nonheat stress conditions. Notably, plants expressing this TAM version prematurely terminate meiosis under heat resulting in unreduced gametes. Thus, the formation of TAM-containing SGs is necessary for genome stability under heat stress.}, author = {De Jaeger-Braet, Joke G and Hartmann, Merle and Böttger, Lev and Yang, Chao and Hamada, Takahiro and Hoth, Stefan and Feng, Xiaoqi and Weingartner, Magdalena and Schnittger, Arp}, issn = {2375-2548}, journal = {Science Advances}, number = {32}, pages = {eadr5694}, publisher = {AAAS}, title = {{The recruitment of the A-type cyclin TAM to stress granules is crucial for meiotic fidelity under heat}}, doi = {10.1126/sciadv.adr5694}, volume = {11}, year = {2025}, } @article{20221, abstract = {We describe the design, synthesis, and single-molecule junction conductance of π-electron molecules bearing both radial and linear π-conjugation pathways, whereby cycloparaphenylene (CPP) radial cores are π-extended linearly with aryl alkyne substituents as models for previously reported CPP-arylene ethynylene conjugated polymers. Although radially and linearly conjugated molecules have been studied previously in isolation as junction-bridging molecular electronic units, this is the first study to examine molecules where both topologies are operative. Our results reveal that the presence of radial CPP components within the junction-spanning pathway leads to a reduction in the conductance of the backbone compared to model linear phenyl substituents. Through tight-binding and DFT-based calculations, we attribute this conductance change to intramolecular van der Waals (vdW) interactions between the CPP ring and the junction-spanning arylene-ethynylene molecular backbone. These interactions induce changes in the dihedral angles of the backbone, leading to a reduced overlap of π orbitals within the molecular junction.}, author = {Shi, Wanzhuo and Wang, Mengjiao and Venkataraman, Latha and Tovar, John D.}, issn = {1530-6992}, journal = {Nano Letters}, number = {31}, pages = {12101--12106}, publisher = {American Chemical Society}, title = {{Single-molecule conductance through hybrid radially and linearly π-conjugated macromolecules reveals an unusual intramolecular π-interaction}}, doi = {10.1021/acs.nanolett.5c03693}, volume = {25}, year = {2025}, } @article{20222, abstract = {Let X be a smooth projective hypersurface defined over Q. We provide new bounds for rational points of bounded height on X. In particular, we show that if X is a smooth projective hypersurface in Pn with n 4 and degree d 50, then the set of rational points on X of height bounded by B have cardinality On,d,ε (Bn−2+ε ). If X is smooth and has degree d 6, we improve the dimension growth conjecture bound. We achieve an analogue result for affine hypersurfaces whose projective closure is smooth.}, author = {Verzobio, Matteo}, issn = {1687-0247}, journal = {International Mathematics Research Notices}, number = {16}, publisher = {Oxford University Press}, title = {{Counting rational points on smooth hypersurfaces with high degree}}, doi = {10.1093/imrn/rnaf249}, volume = {2025}, year = {2025}, } @article{20223, abstract = {The first influential hypothesis for sex chromosome evolution was proposed in 1914 by H. J. Muller, who argued that once recombination was suppressed between the X and Y chromosomes, Y-linked genes become “sheltered” from selection, leading to accumulation of recessive loss-of-function (LOF) mutations and decay of Y-linked genes. The hypothesis fell out of favor in the 1970s because early mathematical models failed to support it and data on the dominance of lethal mutations were viewed as incompatible with the hypothesis. We reevaluate the main arguments against Muller's hypothesis and find that they do not conclusively exclude a role for sheltering in sex chromosome evolution. By relaxing restrictive assumptions of earlier models, we show that sheltering promotes fixation of LOF mutations with sexually dimorphic fitness effects, resulting in decay of X-linked genes that are exclusively expressed by males and Y-linked genes that are primarily, though not necessarily exclusively, expressed by females. We further show that drift and other processes contributing to Y degeneration (i.e. selective interference and regulatory evolution) expand conditions of Y-linked gene loss by sheltering. The actual contribution of sheltering to sex chromosome evolution hinges upon the distribution of dominance and sex-specific fitness effects of LOF mutations, which we discuss.}, author = {Mrnjavac, Andrea and Vicoso, Beatriz and Connallon, Tim}, issn = {1537-1719}, journal = {Molecular Biology and Evolution}, number = {8}, publisher = {Oxford University Press}, title = {{An extension of Muller's sheltering hypothesis for the evolution of sex chromosome gene content}}, doi = {10.1093/molbev/msaf177}, volume = {42}, year = {2025}, } @inproceedings{20224, abstract = {Traffic in datacenters may follow some pattern: some pairs of servers communicate more frequently than others. Demand-oblivious networks may perform poorly for such workloads, and demand-aware networks optimized for traffic should be used instead. Unfortunately, not all shapes of networks are feasible in real hardware. Practical limitations are usually provided in the form of a topology. For example, a network may be required to be a binary tree, a bounded-degree graph or a Fat tree. In this work, we consider a topology of a binary tree, one of the most fundamental network topologies. We show that already finding an optimal demand-aware binary tree network is NP-hard. Then, we explore how various optimization techniques, including simple local searches, as well as deterministic mutation and crossover operators, cope with generating efficient tree networks on real-life and synthetic workloads.}, author = {Martynov, Pavel and Buzdalov, Maxim and Pankratov, Sergei and Aksenov, Vitaliy and Schmid, Stefan}, booktitle = {Proceedings of the 2025 Genetic and Evolutionary Computation Conference}, isbn = {9798400714658}, location = {Malaga, Spain}, pages = {249--257}, publisher = {Association for Computing Machinery}, title = {{In the search of optimal tree networks: Hardness and heuristics}}, doi = {10.1145/3712256.3726425}, year = {2025}, } @inproceedings{20225, abstract = {We present the first supermartingale certificate for quantitative -regular properties of discrete-time infinite-state stochastic systems. Our certificate is defined on the product of the stochastic system and a limit-deterministic Büchi automaton that specifies the property of interest; hence we call it a limit-deterministic Büchi supermartingale (LDBSM). Previously known supermartingale certificates applied only to quantitative reachability, safety, or reach-avoid properties, and to qualitative (i.e., probability 1) -regular properties.We also present fully automated algorithms for the template-based synthesis of LDBSMs, for the case when the stochastic system dynamics and the controller can be represented in terms of polynomial inequalities. Our experiments demonstrate the ability of our method to solve verification and control tasks for stochastic systems that were beyond the reach of previous supermartingale-based approaches.}, author = {Henzinger, Thomas A and Mallik, Kaushik and Sadeghi, Pouya and Zikelic, Dorde}, booktitle = {37th International Conference on Computer Aided Verification}, isbn = {9783031986789}, issn = {1611-3349}, location = {Zagreb, Croatia}, pages = {29--55}, publisher = {Springer Nature}, title = {{Supermartingale certificates for quantitative omega-regular verification and control}}, doi = {10.1007/978-3-031-98679-6_2}, volume = {15932}, year = {2025}, } @phdthesis{20234, abstract = {Game Theory is the mathematical formalization of social dynamics - systems where agents interact over time and the evolution of the state of the system depends on the decisions of every player. This thesis takes the perspective of a single player and focuses on what they can guarantee in the worst case over the behavior of other players. In other words, we consider that the objective of every other player in the game is exactly the opposite to the player. We focus on sustained interactions over time, where the players repeatedly obtain quantitative rewards over time, and they are interested in maximizing their long-term performance. Formally, this thesis focuses on zero-sum games with the liminf average objective. Two fundamental questions that Game Theory aims to answer are the following. 1. How much can a player guarantee to obtain after the interaction? 2. How to act in order to obtain the previously mentioned guarantee? These questions are formalized by the concepts of "value" and "optimal strategies". We study their properties on games that exhibit one or more of the following properties. 1. Partial Observation: the players can not perfectly observe the current state of the system during the game. We consider the model of (finite) Partially Observable Markov Decision Processes and prove that finite-memory strategies are sufficient to approximately guarantee the value. 2. Perturbed Description: the formal description of the game is perturbed by a small parameter. We consider the model of (finite) Perturbed Matrix Games, and provide algorithms to check various robustness properties and to compute the parameterized value and optimal strategies. 3. Stochastic Transitions: the actions of the players determine the behavior of the evolution of the system, described as a probability distribution over the next state. We consider the model of (finite) Perturbed Stochastic Games and provide formulas for the marginal value. 4. Infinite States: the system can be in infinitely many states. We consider the model of Random Dynamic Games on a class of infinite graphs, prove the existence of the value, and quantify the concentration of finite-horizon values.}, author = {Saona Urmeneta, Raimundo J}, issn = {2663-337X}, pages = {125}, publisher = {Institute of Science and Technology Austria}, title = {{Robustness of solutions in game theory : Values and strategies in partially observable, perturbed, stochastic, and infinite games}}, doi = {10.15479/AT-ISTA-20234}, year = {2025}, } @misc{20242, abstract = {This repository contains calculations of carbon footprints of NMR conferences, as described in the article by Lucky N. Kapoor, Natalia Ruzickova, Predrag Živadinović, Valentin Leitner, Maria Anna Sisak, Cecelia Mweka, Jeroen Dobbelaere, Georgios Katsaros, and Paul Schanda Published in Magnetic Resonance, 2025.}, author = {Schanda, Paul}, keywords = {sustainability, conference travel}, publisher = {Institute of Science and Technology Austria}, title = {{Data of: "Quantifying the carbon footprint of conference travel: the case of NMR meetings"}}, doi = {10.15479/AT-ISTA-20242}, year = {2025}, } @article{20249, abstract = {We develop a heuristic for the density of integer points on affine cubic surfaces. Our heuristic applies to smooth surfaces defined by cubic polynomials that are log K3, but it can also be adjusted to handle singular cubic surfaces. We compare our heuristic to Heath-Brown’s prediction for sums of three cubes, as well as to asymptotic formulae in the literature around Zagier’s work on the Markoff cubic surface, and work of Baragar and Umeda on further surfaces of Markoff-type. We also test our heuristic against numerical data for several families of cubic surfaces.}, author = {Browning, Timothy D and Wilsch, Florian Alexander}, issn = {1420-9020}, journal = {Selecta Mathematica New Series}, number = {4}, publisher = {Springer Nature}, title = {{Integral points on cubic surfaces: heuristics and numerics}}, doi = {10.1007/s00029-025-01074-1}, volume = {31}, year = {2025}, } @article{20250, abstract = {Population III stars are possible precursors to early supermassive black holes (BHs). The presence of soft UV Lyman–Werner (LW) background radiation can suppress Population III star formation in minihaloes and allow them to form in pristine atomic-cooling haloes. In the absence of molecular hydrogen (⁠H2⁠) cooling, atomic-cooling haloes enable rapid collapse with suppressed fragmentation. High background LW fluxes from preceding star-formation have been proposed to dissociate H2⁠. This flux can be supplemented by LW radiation from one or more Population III star(s) in the same halo, reducing the necessary background level. Here, we consider atomic-cooling haloes in which multiple protostellar cores form close to one another nearly simultaneously. We assess whether the first star’s LW radiation can dissociate nearby ⁠, enabling rapid accretion on to a nearby protostellar core, and the prompt formation of a second, supermassive star (SMS) from warm, atomically-cooled gas. We use a set of hydrodynamical simulations with the code enzo, with identical LW backgrounds centred on a halo with two adjacent collapsing gas clumps. When an additional large local LW flux is introduced, we observe immediate reductions in both the accretion rates and the stellar masses that form within these clumps. While the LW flux reduces the H2 fraction and increases the gas temperature, the halo core’s potential well is too shallow to promptly heat the gas to >1000 K and increase the second protostar’s accretion rate. We conclude that this internal LW feedback scenario is unlikely to facilitate SMS or massive BH seed formation.}, author = {Sullivan, James and Haiman, Zoltán and Kulkarni, Mihir and Visbal, Eli}, issn = {1365-2966}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {2}, pages = {822--838}, publisher = {Oxford University Press}, title = {{Can supermassive stars form in protogalaxies due to internal Lyman-Werner feedback?}}, doi = {10.1093/mnras/staf1269}, volume = {542}, year = {2025}, } @article{20251, abstract = {The Lane–Emden inequality controls (math. formular) in terms of the L^1 and L^p norms of p. We provide a remainder estimate for this inequality in terms of a suitable distance of p to the manifold of optimizers.}, author = {Carlen, Eric and Lewin, Mathieu and Lieb, Elliott H. and Seiringer, Robert}, issn = {1432-0835}, journal = {Calculus of Variations and Partial Differential Equations}, number = {7}, publisher = {Springer Nature}, title = {{Stability estimate for the Lane–Emden inequality}}, doi = {10.1007/s00526-025-03062-x}, volume = {64}, year = {2025}, } @article{20252, abstract = {Zirconia nanocrystals (ZrO2 NCs) are a stable host material for lanthanides, but their performance lags behind that of the leading NaYF4 nanomaterials. Here, we leverage surface chemistry and core/shell architectures to uncover the contribution of dopants at the nanocrystal surface and of dopants in the nanocrystal bulk. We first assess the doping efficiency by ICP and find that, while Eu is almost quantitatively incorporated, the other lanthanides (La, Ce, Tb, Tm, Er, Yb) have about 50% incorporation efficiency over the studied doping range of 1–10%. We then determine the nanocrystal surface chemistry using NMR spectroscopy, despite the additional spectral line broadening caused by the paramagnetic lanthanide dopants. By varying the surface ligands and measuring the photoluminescence, we resolve the spectroscopic signals that are sensitive to a change in surface chemistry. Time-resolved emission spectra further reinforce the notion of a bulk component with a long luminescent lifetime and a surface component with a fast lifetime. Upon shelling Eu- or Tb-doped zirconia NCs with pure zirconia, the surface component disappears, and the photoluminescence quantum yield increases. We further functionalized the surface of the core/shell particles with oleylphosphonic acid ligands to obtain excellent dispersibility. These results show that lanthanide-doped zirconia NCs can be engineered to eliminate deactivation pathways.}, author = {Reichholf, Nico and Horta, Sharona and Van Der Heggen, David and Seno, Carlotta and Pulparayil Mathew, Jikson and Ibáñez, Maria and Smet, Philippe F. and De Roo, Jonathan}, issn = {1936-086X}, journal = {ACS Nano}, number = {33}, pages = {30371--30382}, publisher = {American Chemical Society}, title = {{Identification and elimination of surface emission in lanthanide (Co)doped zirconia nanocrystals}}, doi = {10.1021/acsnano.5c09137}, volume = {19}, year = {2025}, }