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  • Biogeographic gradients of picoplankton diversity indicate increasing dominance of prokaryotes in warmer Arctic fjords 

    Hörstmann, Cora; Hattermann, Tore; Thomé, Pauline C.; Buttigieg, Pier Luigi; Morel, Isidora; Waite, Anya M.; John, Uwe (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-03-02)
    limate change is opening the Arctic Ocean to increasing human impact and ecosystem changes. Arctic fjords, the region’s most productive ecosystems, are sustained by a diverse microbial community at the base of the food web. Here we show that Arctic fjords become more prokaryotic in the picoplankton (0.2–3 µm) with increasing water temperatures. Across 21 fjords, we found that Arctic fjords had ...
  • Linear codes associated to symmetric determinantal varieties: Even rank case 

    Beelen, Peter; Johnsen, Trygve; Singh, Prasant (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-20)
    We consider linear codes over a finite field Fq, for odd q, derived from determinantal varieties, obtained from symmetric matrices of bounded ranks. A formula for the weight of a codeword is derived. Using this formula, we have computed the minimum distance for the codes corresponding to matrices upperbounded by any fixed, even rank. A conjecture is proposed for the cases where the upper bound is ...
  • Exceptionally simple super-PDE for F (4) 

    Santi, Andrea; The, Dennis (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-02-01)
    For the largest exceptional simple Lie superalgebra F(4), having dimension (24|16), we provide two explicit geometric realizations as supersymmetries, namely as the symmetry superalgebra of super-PDE systems of second and third order respectively.
  • ODEs whose Symmetry Groups are not Fiber-Preserving 

    Kruglikov, Boris Serafimovich; Schneider, Eivind (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
    We observe that, up to conjugation, a majority of higher order ODEs (ordinary differential equations) and ODE systems have only fiber-preserving point symmetries. By exploiting Lie's classification of Lie algebras of vector fields, we describe all exceptions to this in the case of scalar ODEs and systems of ODEs on a pair of functions. The scalar ODEs whose symmetry algebras are not fiber preserving ...
  • Decomposable (5, 6)-solutions in eleven-dimensional supergravity 

    Chi, Hanci; Chrysikos, Ioannis; Schneider, Eivind (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-08)
    We present decomposable (5, 6)-solutions M<sup>1,4</sup>×M<sup>6</sup> in eleven-dimensional supergravity by solving the bosonic supergravity equations for a variety of non-trivial flux forms. Many of the bosonic backgrounds presented here are induced by various types of null flux forms on products of certain totally Ricci-isotropic Lorentzian Walker manifolds and Ricci-flat Riemannian manifolds. ...
  • Power availability of PV plus thermal batteries in real-world electric power grids 

    Foldvik Eikeland, Odin; Kelsall, Colin C.; Buznitsky, Kyle; Verma, Shomik; Bianchi, Filippo Maria; Chiesa, Matteo; Henry, Asegun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-25)
    As variable renewable energy sources comprise a growing share of total electricity generation, energy storage technologies are becoming increasingly critical for balancing energy generation and demand.<p> <p>In this study, a real-world electricity system was modeled rather than modeling hypothetical future electric power systems where the existing electricity infrastructure are neglected. In ...
  • The expressive power of pooling in Graph Neural Networks 

    Bianchi, Filippo Maria; Lachi, Veronica (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
    In Graph Neural Networks (GNNs), hierarchical pooling operators generate local summaries of the data by coarsening the graph structure and the vertex features. While considerable attention has been devoted to analyzing the expressive power of message-passing (MP) layers in GNNs, a study on how graph pooling affects the expressiveness of a GNN is still lacking. Additionally, despite the recent advances ...
  • Total Variation Graph Neural Networks 

    Hansen, Jonas Berg; Bianchi, Filippo Maria (Journal article; Tidsskriftartikkel, 2023-07)
    Recently proposed Graph Neural Networks (GNNs) for vertex clustering are trained with an unsupervised minimum cut objective, approximated by a Spectral Clustering (SC) relaxation. However, the SC relaxation is loose and, while it offers a closed-form solution, it also yields overly smooth cluster assignments that poorly separate the vertices. In this paper, we propose a GNN model that computes cluster ...
  • On C-class equations 

    Čap, Andreas; Doubrov, Boris; The, Dennis (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-29)
    The concept of a C-class of differential equations goes back to E. Cartan with the upshot that generic equations in a C-class can be solved without integration. While Cartan’s definition was in terms of differential invariants being first integrals, all results exhibiting C-classes that we are aware of are based on the fact that a canonical Cartan geometry associated to the equations in the class ...
  • Double Schubert polynomials do have saturated Newton polytopes 

    Castillo, Federico; Cid-Ruiz, Yairon; Mohammadi, Fatemeh; Montaño, Jonathan (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-11-03)
    We prove that double Schubert polynomials have the saturated Newton polytope property. This settles a conjecture by Monical, Tokcan and Yong. Our ideas are motivated by the theory of multidegrees. We introduce a notion of standardization of ideals that enables us to study nonstandard multigradings. This allows us to show that the support of the multidegree polynomial of each Cohen–Macaulay prime ...
  • Bianchi type cosmological models in f(T) tele-parallel gravity 

    van den Hoogen, Robert; Coley, Alan; McNutt, David Duncan (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-12)
    Symmetry assumptions on the geometrical framework have provided successful mechanisms to develop physically meaningful solutions to many problems. In tele-parallel gravity, invariance of the frame and spin-connection under a group of motions defines an affine symmetry group. Here, we assume there exists a three-dimensional group of affine symmetries acting simply transitively on a spatial hypersurface ...
  • Associations and predictive power of dietary patterns on metabolic syndrome and its components 

    Moe, Åse Mari; Ytterstad, Elinor; Hopstock, Laila Arnesdatter; Løvsletten, Ola; Carlsen, Monica Hauger; Sørbye, Sigrunn Holbek (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-31)
    Background and aims: Metabolic syndrome (MetS) defines important risk factors in the development of cardiovascular diseases and other serious health conditions. This study aims to investigate the influence of different dietary patterns on MetS and its components, examining both associations and predictive performance.<p> <p>Methods and results: The study sample included 10,750 participants from ...
  • Probabilistic Load Forecasting With Reservoir Computing 

    Guerra, Michele; Bianchi, Filippo Maria; Scardapane, Simone (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-15)
    Some applications of deep learning require not only to provide accurate results but also to quantify the amount of confidence in their prediction. The management of an electric power grid is one of these cases: to avoid risky scenarios, decision-makers need both precise and reliable forecasts of, for example, power loads. For this reason, point forecasts are not enough hence it is necessary to adopt ...
  • Probabilistic load forecasting with Reservoir Computing 

    Guerra, Michele; Bianchi, Filippo Maria; Scardapane, Simone (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-15)
    Some applications of deep learning require not only to provide accurate results but also to quantify the amount of confidence in their prediction. The management of an electric power grid is one of these cases: to avoid risky scenarios, decision-makers need both precise and reliable forecasts of, for example, power loads. For this reason, point forecasts are not enough hence it is necessary to adopt ...
  • Numerical evaluation of line, surface and toroidal integrals on level sets of toroidally symmetric functions 

    Wiesenberger, Matthias; Gerrú, Raul; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-05)
    We investigate strategies to numerically integrate closed lines and surfaces that are implicitly defined by level sets (iso-contours) of continuously differentiable toroidally symmetric functions. The “grid-transform” approach transforms quantities given in non-surface-aligned coordinates onto a numerically constructed surface-aligned grid. Here, line and surface integrals, as well as so-called ...
  • Interplay between advective, diffusive and active barriers in (rotating) Rayleigh-Bénard flow 

    Aksamit, Nikolas Olson; Hartmann, Robert; Lohse, Detlef; Haller, George (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-08-22)
    Our understanding of the material organization of complex fluid flows has benefited recently from mathematical developments in the theory of objective coherent structures. These methods have provided a wealth of approaches that identify transport barriers in three-dimensional (3-D) turbulent flows. Specifically, theoretical advances have been incorporated into numerical algorithms that extract ...
  • A finite volume flux coordinate independent approach 

    Wiesenberger, Matthias; Held, Markus (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-03)
    We present a novel family of schemes as the merging between a one-dimensional advection scheme with the flux coordinate independent approach. The scheme can be used to discretize the field-aligned NavierStokes equations in three dimensions. Our approach consists of three major steps: (i) the formulation of the one-dimensional scheme in a locally field-aligned coordinate system, (ii) a numerical ...
  • Evaluating Deep Q-Learning Algorithms for Controlling Blood Glucose in In Silico Type 1 Diabetes 

    Angel, Tejedor H Miguel; Hjerde, Sigurd; Myhre, Jonas Nordhaug; Godtliebsen, Fred (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-07)
    Patients with type 1 diabetes must continually decide how much insulin to inject before each meal to maintain blood glucose levels within a healthy range. Recent research has worked on a solution for this burden, showing the potential of reinforcement learning as an emerging approach for the task of controlling blood glucose levels. In this paper, we test and evaluate several deep Q-learning algorithms ...
  • Generalized Teleparallel de Sitter geometries 

    Coley, Alan; Landry, Alexandre; van den Hoogen, Robert; McNutt, David Duncan (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-30)
    Theories of gravity based on teleparallel geometries are characterized by the torsion, which is a function of the coframe, derivatives of the coframe, and a zero curvature and metric compatible spin-connection. The appropriate notion of a symmetry in a teleparallel geometry is that of an affine symmetry. Due to the importance of the de Sitter geometry and Einstein spaces within General Relativity, ...
  • The poset of Specht ideals for hyperoctahedral groups 

    Debus, Sebastian; Moustrou, Philippe; Riener, Cordian Benedikt; Verdure, Hugues (Journal article; Tidsskriftartikkel, 2023)
    Specht polynomials classically realize the irreducible representations of the symmetric group. The ideals defined by these polynomials provide a strong connection with the combinatorics of Young tableaux and have been intensively studied by several authors. We initiate similar investigations for the ideals defined by the Specht polynomials associated to the hyperoctahedral group <i>B<sub>n</sub></i>. ...

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