--- _id: '12312' abstract: - lang: eng text: "Let $\\ell$ be a prime number. We classify the subgroups $G$ of $\\operatorname{Sp}_4(\\mathbb{F}_\\ell)$ and $\\operatorname{GSp}_4(\\mathbb{F}_\\ell)$ that act irreducibly on $\\mathbb{F}_\\ell^4$, but such that every element of $G$ fixes an $\\mathbb{F}_\\ell$-vector subspace of dimension 1. We use this classification to prove that the local-global principle for isogenies of degree $\\ell$ between abelian surfaces over number fields holds in many cases -- in particular, whenever the abelian surface has non-trivial endomorphisms and $\\ell$ is large enough with respect to the field of definition. Finally, we prove that there exist arbitrarily large primes $\\ell$ for which some abelian surface\r\n$A/\\mathbb{Q}$ fails the local-global principle for isogenies of degree $\\ell$." acknowledgement: "It is a pleasure to thank Samuele Anni for his interest in this project and for several discussions on the topic of this paper, which led in particular to Remark 6.30 and to a better understanding of the difficulties with [6]. We also thank John Cullinan for correspondence about [6] and Barinder Banwait for his many insightful comments on the first version of this paper. Finally, we thank the referee for their thorough reading of the manuscript.\r\nOpen access funding provided by Università di Pisa within the CRUI-CARE Agreement. The authors have been partially supported by MIUR (Italy) through PRIN 2017 “Geometric, algebraic and analytic methods in arithmetic\" and PRIN 2022 “Semiabelian varieties, Galois representations and related Diophantine problems\", and by the University of Pisa through PRA 2018-19 and 2022 “Spazi di moduli, rappresentazioni e strutture combinatorie\". The first author is a member of the INdAM group GNSAGA." article_number: '18' article_processing_charge: Yes (via OA deal) article_type: original author: - first_name: Davide full_name: Lombardo, Davide last_name: Lombardo - first_name: Matteo full_name: Verzobio, Matteo id: 7aa8f170-131e-11ed-88e1-a9efd01027cb last_name: Verzobio orcid: 0000-0002-0854-0306 citation: ama: Lombardo D, Verzobio M. On the local-global principle for isogenies of abelian surfaces. Selecta Mathematica. 2024;30(2). doi:10.1007/s00029-023-00908-0 apa: Lombardo, D., & Verzobio, M. (2024). On the local-global principle for isogenies of abelian surfaces. Selecta Mathematica. Springer Nature. https://doi.org/10.1007/s00029-023-00908-0 chicago: Lombardo, Davide, and Matteo Verzobio. “On the Local-Global Principle for Isogenies of Abelian Surfaces.” Selecta Mathematica. Springer Nature, 2024. https://doi.org/10.1007/s00029-023-00908-0. ieee: D. Lombardo and M. Verzobio, “On the local-global principle for isogenies of abelian surfaces,” Selecta Mathematica, vol. 30, no. 2. Springer Nature, 2024. ista: Lombardo D, Verzobio M. 2024. On the local-global principle for isogenies of abelian surfaces. Selecta Mathematica. 30(2), 18. mla: Lombardo, Davide, and Matteo Verzobio. “On the Local-Global Principle for Isogenies of Abelian Surfaces.” Selecta Mathematica, vol. 30, no. 2, 18, Springer Nature, 2024, doi:10.1007/s00029-023-00908-0. short: D. Lombardo, M. Verzobio, Selecta Mathematica 30 (2024). date_created: 2023-01-16T11:45:53Z date_published: 2024-01-26T00:00:00Z date_updated: 2024-02-05T12:25:00Z day: '26' department: - _id: TiBr doi: 10.1007/s00029-023-00908-0 external_id: arxiv: - '2206.15240' intvolume: ' 30' issue: '2' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/2206.15240 month: '01' oa: 1 oa_version: Preprint publication: Selecta Mathematica publication_identifier: eissn: - 1420-9020 issn: - 1022-1824 publication_status: epub_ahead publisher: Springer Nature quality_controlled: '1' scopus_import: '1' status: public title: On the local-global principle for isogenies of abelian surfaces type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 30 year: '2024' ... --- _id: '14930' abstract: - lang: eng text: In this paper we investigate locally free representations of a quiver Q over a commutative Frobenius algebra R by arithmetic Fourier transform. When the base field is finite we prove that the number of isomorphism classes of absolutely indecomposable locally free representations of fixed rank is independent of the orientation of Q. We also prove that the number of isomorphism classes of locally free absolutely indecomposable representations of the preprojective algebra of Q over R equals the number of isomorphism classes of locally free absolutely indecomposable representations of Q over R[t]/(t2). Using these results together with results of Geiss, Leclerc and Schröer we give, when k is algebraically closed, a classification of pairs (Q, R) such that the set of isomorphism classes of indecomposable locally free representations of Q over R is finite. Finally when the representation is free of rank 1 at each vertex of Q, we study the function that counts the number of isomorphism classes of absolutely indecomposable locally free representations of Q over the Frobenius algebra Fq[t]/(tr). We prove that they are polynomial in q and their generating function is rational and satisfies a functional equation. acknowledgement: Special thanks go to Christof Geiss, Bernard Leclerc and Jan Schröer for explaining their work but also for sharing some unpublished results with us. We also thank the referee for many useful suggestions. We would like to thank Tommaso Scognamiglio for pointing out a mistake in the proof of Proposition 5.17 in an earlier version of the paper. We would like also to thank Alexander Beilinson, Bill Crawley-Boevey, Joel Kamnitzer, and Peng Shan for useful discussions. article_number: '20' article_processing_charge: No article_type: original author: - first_name: Tamás full_name: Hausel, Tamás id: 4A0666D8-F248-11E8-B48F-1D18A9856A87 last_name: Hausel - first_name: Emmanuel full_name: Letellier, Emmanuel last_name: Letellier - first_name: Fernando full_name: Rodriguez-Villegas, Fernando last_name: Rodriguez-Villegas citation: ama: Hausel T, Letellier E, Rodriguez-Villegas F. Locally free representations of quivers over commutative Frobenius algebras. Selecta Mathematica. 2024;30(2). doi:10.1007/s00029-023-00914-2 apa: Hausel, T., Letellier, E., & Rodriguez-Villegas, F. (2024). Locally free representations of quivers over commutative Frobenius algebras. Selecta Mathematica. Springer Nature. https://doi.org/10.1007/s00029-023-00914-2 chicago: Hausel, Tamás, Emmanuel Letellier, and Fernando Rodriguez-Villegas. “Locally Free Representations of Quivers over Commutative Frobenius Algebras.” Selecta Mathematica. Springer Nature, 2024. https://doi.org/10.1007/s00029-023-00914-2. ieee: T. Hausel, E. Letellier, and F. Rodriguez-Villegas, “Locally free representations of quivers over commutative Frobenius algebras,” Selecta Mathematica, vol. 30, no. 2. Springer Nature, 2024. ista: Hausel T, Letellier E, Rodriguez-Villegas F. 2024. Locally free representations of quivers over commutative Frobenius algebras. Selecta Mathematica. 30(2), 20. mla: Hausel, Tamás, et al. “Locally Free Representations of Quivers over Commutative Frobenius Algebras.” Selecta Mathematica, vol. 30, no. 2, 20, Springer Nature, 2024, doi:10.1007/s00029-023-00914-2. short: T. Hausel, E. Letellier, F. Rodriguez-Villegas, Selecta Mathematica 30 (2024). date_created: 2024-02-04T23:00:53Z date_published: 2024-01-27T00:00:00Z date_updated: 2024-02-05T12:58:21Z day: '27' department: - _id: TaHa doi: 10.1007/s00029-023-00914-2 intvolume: ' 30' issue: '2' language: - iso: eng month: '01' oa_version: None publication: Selecta Mathematica publication_identifier: eissn: - 1420-9020 issn: - 1022-1824 publication_status: epub_ahead publisher: Springer Nature quality_controlled: '1' scopus_import: '1' status: public title: Locally free representations of quivers over commutative Frobenius algebras type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 30 year: '2024' ... --- _id: '14885' abstract: - lang: eng text: The near-surface boundary layer can mediate the response of mountain glaciers to external climate, cooling the overlying air and promoting a density-driven glacier wind. The fundamental processes are conceptually well understood, though the magnitudes of cooling and presence of glacier winds are poorly quantified in space and time, increasing the forcing uncertainty for melt models. We utilize a new data set of on-glacier meteorological measurements on three neighboring glaciers in the Swiss Alps to explore their distinct response to regional climate under the extreme 2022 summer. We find that synoptic wind origins and local terrain modifications, not only glacier size, play an important role in the ability of a glacier to cool the near-surface air. Warm air intrusions from valley or synoptically-driven winds onto the glacier can occur between ∼19% and 64% of the time and contribute between 3% and 81% of the total sensible heat flux to the surface during warm afternoon hours, depending on the fetch of the glacier flowline and its susceptibility to boundary layer erosion. In the context of extreme summer warmth, indicative of future conditions, the boundary layer cooling (up to 6.5°C cooler than its surroundings) and resultant katabatic wind flow are highly heterogeneous between the study glaciers, highlighting the complex and likely non-linear response of glaciers to an uncertain future. acknowledgement: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 101026058. The authors acknowledge the invaluable field assistance of Marta Corrà, Achille Jouberton, Marin Kneib, Stefan Fugger, Celine Ducret and Alexander Groos. The authors would also like to thank Luca Carturan for advice regarding AWS setup and maintenance and Simone Fatichi for provision and support in the use of the Tethys-Chloris model. Open access funding provided by ETH-Bereich Forschungsanstalten. article_number: e2023JD040214 article_processing_charge: Yes (in subscription journal) article_type: original author: - first_name: Thomas full_name: Shaw, Thomas id: 3caa3f91-1f03-11ee-96ce-e0e553054d6e last_name: Shaw orcid: 0000-0001-7640-6152 - first_name: Pascal full_name: Buri, Pascal id: 317987aa-9421-11ee-ac5a-b941b041abba last_name: Buri - first_name: Michael full_name: Mccarthy, Michael id: 22a2674a-61ce-11ee-94b5-d18813baf16f last_name: Mccarthy - first_name: Evan S. full_name: Miles, Evan S. last_name: Miles - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti orcid: 0000-0002-5554-8087 citation: ama: 'Shaw T, Buri P, McCarthy M, Miles ES, Pellicciotti F. Local controls on near-surface glacier cooling under warm atmospheric conditions. Journal of Geophysical Research: Atmospheres. 2024;129(2). doi:10.1029/2023JD040214' apa: 'Shaw, T., Buri, P., McCarthy, M., Miles, E. S., & Pellicciotti, F. (2024). Local controls on near-surface glacier cooling under warm atmospheric conditions. Journal of Geophysical Research: Atmospheres. Wiley. https://doi.org/10.1029/2023JD040214' chicago: 'Shaw, Thomas, Pascal Buri, Michael McCarthy, Evan S. Miles, and Francesca Pellicciotti. “Local Controls on Near-Surface Glacier Cooling under Warm Atmospheric Conditions.” Journal of Geophysical Research: Atmospheres. Wiley, 2024. https://doi.org/10.1029/2023JD040214.' ieee: 'T. Shaw, P. Buri, M. McCarthy, E. S. Miles, and F. Pellicciotti, “Local controls on near-surface glacier cooling under warm atmospheric conditions,” Journal of Geophysical Research: Atmospheres, vol. 129, no. 2. Wiley, 2024.' ista: 'Shaw T, Buri P, McCarthy M, Miles ES, Pellicciotti F. 2024. Local controls on near-surface glacier cooling under warm atmospheric conditions. Journal of Geophysical Research: Atmospheres. 129(2), e2023JD040214.' mla: 'Shaw, Thomas, et al. “Local Controls on Near-Surface Glacier Cooling under Warm Atmospheric Conditions.” Journal of Geophysical Research: Atmospheres, vol. 129, no. 2, e2023JD040214, Wiley, 2024, doi:10.1029/2023JD040214.' short: 'T. Shaw, P. Buri, M. McCarthy, E.S. Miles, F. Pellicciotti, Journal of Geophysical Research: Atmospheres 129 (2024).' date_created: 2024-01-28T23:01:42Z date_published: 2024-01-28T00:00:00Z date_updated: 2024-02-06T08:44:02Z day: '28' ddc: - '550' department: - _id: FrPe doi: 10.1029/2023JD040214 file: - access_level: open_access checksum: cad5b93caadb40c14e5faedc34f7bba7 content_type: application/pdf creator: dernst date_created: 2024-02-06T08:38:27Z date_updated: 2024-02-06T08:38:27Z file_id: '14943' file_name: 2024_JGRAtmospheres_Shaw.pdf file_size: 7481087 relation: main_file success: 1 file_date_updated: 2024-02-06T08:38:27Z has_accepted_license: '1' intvolume: ' 129' issue: '2' language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '01' oa: 1 oa_version: Published Version publication: 'Journal of Geophysical Research: Atmospheres' publication_identifier: eissn: - 2169-8996 issn: - 2169-897X publication_status: published publisher: Wiley quality_controlled: '1' related_material: record: - id: '14919' relation: research_data status: public scopus_import: '1' status: public title: Local controls on near-surface glacier cooling under warm atmospheric conditions tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 129 year: '2024' ... --- _id: '14938' abstract: - lang: eng text: High elevation headwater catchments are complex hydrological systems that seasonally buffer water and release it in the form of snow and ice melt, modulating downstream runoff regimes and water availability. In High Mountain Asia (HMA), where a wide range of climates from semi-arid to monsoonal exist, the importance of the cryospheric contributions to the water budget varies with the amount and seasonal distribution of precipitation. Losses due to evapotranspiration and sublimation are to date largely unquantified components of the water budget in such catchments, although they can be comparable in magnitude to glacier melt contributions to streamflow. 
Here, we simulate the hydrology of three high elevation headwater catchments in distinct climates in HMA over 10 years using an ecohydrological model geared towards high-mountain areas including snow and glaciers, forced with reanalysis data. 
Our results show that evapotranspiration and sublimation together are most important at the semi-arid site, Kyzylsu, on the northernmost slopes of the Pamir mountain range. Here, the evaporative loss amounts to 28% of the water throughput, which we define as the total water added to, or removed from the water balance within a year. In comparison, evaporative losses are 19% at the Central Himalayan site Langtang and 13% at the wettest site, 24K, on the Southeastern Tibetan Plateau. At the three sites, respectively, sublimation removes 15%, 13% and 6% of snowfall, while evapotranspiration removes the equivalent of 76%, 28% and 19% of rainfall. In absolute terms, and across a comparable elevation range, the highest ET flux is 413 mm yr-1 at 24K, while the highest sublimation flux is 91 mm yr-1 at Kyzylsu. During warm and dry years, glacier melt was found to only partially compensate for the annual supply deficit. article_processing_charge: Yes article_type: original author: - first_name: Stefan full_name: Fugger, Stefan id: 86698d64-c4c6-11ee-af02-cdf1e6a7d31f last_name: Fugger - first_name: Thomas full_name: Shaw, Thomas id: 3caa3f91-1f03-11ee-96ce-e0e553054d6e last_name: Shaw orcid: 0000-0001-7640-6152 - first_name: Achille full_name: Jouberton, Achille last_name: Jouberton - first_name: Evan full_name: Miles, Evan last_name: Miles - first_name: Pascal full_name: Buri, Pascal id: 317987aa-9421-11ee-ac5a-b941b041abba last_name: Buri - first_name: Michael full_name: McCarthy, Michael id: 22a2674a-61ce-11ee-94b5-d18813baf16f last_name: McCarthy - first_name: Catriona Louise full_name: Fyffe, Catriona Louise id: 001b0422-8d15-11ed-bc51-cab6c037a228 last_name: Fyffe - first_name: Simone full_name: Fatichi, Simone last_name: Fatichi - first_name: Marin full_name: Kneib, Marin last_name: Kneib - first_name: Peter full_name: Molnar, Peter last_name: Molnar - first_name: Francesca full_name: Pellicciotti, Francesca id: b28f055a-81ea-11ed-b70c-a9fe7f7b0e70 last_name: Pellicciotti orcid: 0000-0002-5554-8087 citation: ama: Fugger S, Shaw T, Jouberton A, et al. Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia. Environmental Research Letters. doi:10.1088/1748-9326/ad25a0 apa: Fugger, S., Shaw, T., Jouberton, A., Miles, E., Buri, P., McCarthy, M., … Pellicciotti, F. (n.d.). Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia. Environmental Research Letters. IOP Publishing. https://doi.org/10.1088/1748-9326/ad25a0 chicago: Fugger, Stefan, Thomas Shaw, Achille Jouberton, Evan Miles, Pascal Buri, Michael McCarthy, Catriona Louise Fyffe, et al. “Hydrological Regimes and Evaporative Flux Partitioning at the Climatic Ends of High Mountain Asia.” Environmental Research Letters. IOP Publishing, n.d. https://doi.org/10.1088/1748-9326/ad25a0. ieee: S. Fugger et al., “Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia,” Environmental Research Letters. IOP Publishing. ista: Fugger S, Shaw T, Jouberton A, Miles E, Buri P, McCarthy M, Fyffe CL, Fatichi S, Kneib M, Molnar P, Pellicciotti F. Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia. Environmental Research Letters. mla: Fugger, Stefan, et al. “Hydrological Regimes and Evaporative Flux Partitioning at the Climatic Ends of High Mountain Asia.” Environmental Research Letters, IOP Publishing, doi:10.1088/1748-9326/ad25a0. short: S. Fugger, T. Shaw, A. Jouberton, E. Miles, P. Buri, M. McCarthy, C.L. Fyffe, S. Fatichi, M. Kneib, P. Molnar, F. Pellicciotti, Environmental Research Letters (n.d.). date_created: 2024-02-05T09:01:11Z date_published: 2024-02-02T00:00:00Z date_updated: 2024-02-06T08:35:39Z day: '02' ddc: - '550' department: - _id: FrPe doi: 10.1088/1748-9326/ad25a0 has_accepted_license: '1' keyword: - Public Health - Environmental and Occupational Health - General Environmental Science - Renewable Energy - Sustainability and the Environment language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1088/1748-9326/ad25a0 month: '02' oa: 1 oa_version: Published Version publication: Environmental Research Letters publication_identifier: issn: - 1748-9326 publication_status: accepted publisher: IOP Publishing quality_controlled: '1' status: public title: Hydrological regimes and evaporative flux partitioning at the climatic ends of High Mountain Asia tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 year: '2024' ... --- _id: '14213' abstract: - lang: eng text: We introduce a method to segment the visual field into independently moving regions, trained with no ground truth or supervision. It consists of an adversarial conditional encoder-decoder architecture based on Slot Attention, modified to use the image as context to decode optical flow without attempting to reconstruct the image itself. In the resulting multi-modal representation, one modality (flow) feeds the encoder to produce separate latent codes (slots), whereas the other modality (image) conditions the decoder to generate the first (flow) from the slots. This design frees the representation from having to encode complex nuisance variability in the image due to, for instance, illumination and reflectance properties of the scene. Since customary autoencoding based on minimizing the reconstruction error does not preclude the entire flow from being encoded into a single slot, we modify the loss to an adversarial criterion based on Contextual Information Separation. The resulting min-max optimization fosters the separation of objects and their assignment to different attention slots, leading to Divided Attention, or DivA. DivA outperforms recent unsupervised multi-object motion segmentation methods while tripling run-time speed up to 104FPS and reducing the performance gap from supervised methods to 12% or less. DivA can handle different numbers of objects and different image sizes at training and test time, is invariant to permutation of object labels, and does not require explicit regularization. article_processing_charge: No author: - first_name: Dong full_name: Lao, Dong last_name: Lao - first_name: Zhengyang full_name: Hu, Zhengyang last_name: Hu - first_name: Francesco full_name: Locatello, Francesco id: 26cfd52f-2483-11ee-8040-88983bcc06d4 last_name: Locatello orcid: 0000-0002-4850-0683 - first_name: Yanchao full_name: Yang, Yanchao last_name: Yang - first_name: Stefano full_name: Soatto, Stefano last_name: Soatto citation: ama: 'Lao D, Hu Z, Locatello F, Yang Y, Soatto S. Divided attention: Unsupervised multi-object discovery with contextually separated slots. In: 1st Conference on Parsimony and Learning. ; 2024.' apa: 'Lao, D., Hu, Z., Locatello, F., Yang, Y., & Soatto, S. (2024). Divided attention: Unsupervised multi-object discovery with contextually separated slots. In 1st Conference on Parsimony and Learning. Hong Kong, China.' chicago: 'Lao, Dong, Zhengyang Hu, Francesco Locatello, Yanchao Yang, and Stefano Soatto. “Divided Attention: Unsupervised Multi-Object Discovery with Contextually Separated Slots.” In 1st Conference on Parsimony and Learning, 2024.' ieee: 'D. Lao, Z. Hu, F. Locatello, Y. Yang, and S. Soatto, “Divided attention: Unsupervised multi-object discovery with contextually separated slots,” in 1st Conference on Parsimony and Learning, Hong Kong, China, 2024.' ista: 'Lao D, Hu Z, Locatello F, Yang Y, Soatto S. 2024. Divided attention: Unsupervised multi-object discovery with contextually separated slots. 1st Conference on Parsimony and Learning. CPAL: Conference on Parsimony and Learning.' mla: 'Lao, Dong, et al. “Divided Attention: Unsupervised Multi-Object Discovery with Contextually Separated Slots.” 1st Conference on Parsimony and Learning, 2024.' short: D. Lao, Z. Hu, F. Locatello, Y. Yang, S. Soatto, in:, 1st Conference on Parsimony and Learning, 2024. conference: end_date: 2024-01-03 location: Hong Kong, China name: 'CPAL: Conference on Parsimony and Learning' start_date: 2024-01-03 date_created: 2023-08-22T14:19:59Z date_published: 2024-01-03T00:00:00Z date_updated: 2024-02-12T08:56:23Z day: '03' ddc: - '000' department: - _id: FrLo external_id: arxiv: - '2304.01430' file: - access_level: open_access checksum: 8fad894c34f1b3d5a14fb8ffb12f7277 content_type: application/pdf creator: dernst date_created: 2024-02-12T08:40:36Z date_updated: 2024-02-12T08:40:36Z file_id: '14978' file_name: 2024_CPAL_Lao.pdf file_size: 8038511 relation: main_file success: 1 file_date_updated: 2024-02-12T08:40:36Z has_accepted_license: '1' language: - iso: eng month: '01' oa: 1 oa_version: Published Version publication: 1st Conference on Parsimony and Learning publication_status: published quality_controlled: '1' status: public title: 'Divided attention: Unsupervised multi-object discovery with contextually separated slots' type: conference user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 year: '2024' ...