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Università della Svizzera italiana

Space–time shape uncertainties in the forward and inverse problem of electrocardiography

Gander, Lia ; Krause, Rolf ; Multerer, Michael ; Pezzuto, Simone

In: International journal for numerical methods in biomedical engineering, 2021, vol. 37, no. 10, p. 23

In electrocardiography, the “classic” inverse problem is the reconstruction of electric potentials at a surface enclosing the heart from remote recordings at the body surface and an accurate description of the anatomy. The latter being affected by noise and obtained with limited resolution due to clinical constraints, a possibly large uncertainty may be perpetuated in the inverse ...

Università della Svizzera italiana

A fast direct solver for nonlocal operators in wavelet coordinates

Harbrecht, Helmut ; Multerer, Michael

In: Journal of computational physics, 2021, vol. 428, p. 15 p

In this article, we consider fast direct solvers for nonlocal operators. The pivotal idea is to combine a wavelet representation of the system matrix, yielding a quasi- sparse matrix, with the nested dissection ordering scheme. The latter drastically reduces the fill-in during the factorization of the system matrix by means of a Cholesky decomposition or an LU decomposition, respectively. This...

Université de Fribourg

Twenty-seven Years of Service Research : a Literature Review and Research Agenda

Furrer, Olivier ; Yu Kerguignas, Jie ; Delcourt, Cécile ; Gremler, Dwayne D.

In: Journal of Services Marketing, 2020, vol. 34, no. 3, p. 299-316

Purpose – The growing service sector has experienced several revolutions that have transformed the way services are created and delivered. In parallel, services increasingly pique the interest of scholars, resulting in an expanding body of knowledge. Accordingly, it is time to reflect on extant service research, assess its boundaries, and think about its future. This paper aims to consider...

Université de Fribourg

Ecoregional Governance: Transboundary Environmental Cooperation in the Carpatho-Danubian Area

Voyloshnikova, Daria ; Casasus, Gilbert (Dir.)

Thèse de doctorat : Université de Fribourg, 2020.

The dissertation examines the contemporary environmental governance complex covering the transboundary area of the Carpathians and Danube with a focus on ecoregional approach. The strategic importance of these two geographical objects accounts for an intertwined system of varied institutions and initiatives contributing to addressing ecological challenges in the area through international...

Consortium of Swiss Academic Libraries

Program repair without regret

von Essen, Christian ; Jobstmann, Barbara

In: Formal Methods in System Design, 2015, vol. 47, no. 1, p. 26-50

Université de Fribourg

Geochemical fingerprinting of key lithologies and depositional processes across the upper boundary of the Opalinus Clay (Aalenian, Middle Jurassic, northern Switzerland)

Lauper, Bruno ; Deplazes, Gaudenz ; Vogel, Hendrik ; Jaeggi, David ; Wohlwend, Stephan ; Ariztegui, Daniel ; Foubert, Anneleen

In: The Depositional Record, 2021, vol. 7, no. 1, p. 25-51

The Opalinus Clay is an argillaceous to silty mudstone formation, notable in Switzerland as the selected host rock for deep geological disposal of radioactive waste. Its upper bounding unit (Passwang Formation and eastern equivalents) is composed of successions of mudstone, sandy bioclastic marl and limestone separated by ooidal ironstone beds. The lithostratigraphic transition is diachronous...

Università della Svizzera italiana

Multilevel solution strategies for unfitted finite element methods

Kothari, Hardik ; Krause, Rolf (Dir.)

Thèse de doctorat : Università della Svizzera italiana, 2020 ; 2020INFO009.

In the unfitted finite element methods, traditionally we can use Nitsche's method or the method of Lagrange multipliers to enforce the boundary/interface conditions. In this work, we present tailored multilevel methods for solving the problems stemming from either of these discretizations. Generally, multigrid methods require a hierarchy of finite element (FE) spaces which can be created...

Université de Fribourg

The Holders of Human Rights : The Bright Side of Human Rights?

Besson, Samantha

In: The Oxford Handbook of Global Justice, 2020, p. 99-121

International human rights law and practice reveal an ambivalent approach to the personal scope of human rights: human rights are often less equal or general than they claim and are claimed to be. The inequalities of human rights are of two kinds: some vulnerable individuals are also protected by special rights, thus drawing an internal boundary within the scope of human rights-holders, while...

Université de Fribourg

Collective modes in excitonic insulators: Effects of electron-phonon coupling and signatures in the optical response

Murakami, Yuta ; Golež, Denis ; Kaneko, Tatsuya ; Koga, Akihisa ; Millis, Andrew J. ; Werner, Philipp

In: Physical Review B, 2020, vol. 101, no. 19, p. 195118

We consider a two-band spinless model describing an excitonic insulator (EI) on the two-dimensional square lattice with anisotropic hopping parameters and electron-phonon (el-ph) coupling, inspired by the EI candidate Ta2NiSe5. We systematically study the nature of the collective excitations in the ordered phase which originates from the interband Coulomb interaction and the el-ph coupling. ...

Université de Fribourg

Ideal polyhedral surfaces in Fuchsian manifolds

Prosanov, Roman

In: Geometriae Dedicata, 2020, vol. 206, no. 1, p. 151–179

Let Sg,n be a surface of genus g>1 with n>0 punctures equipped with a complete hyperbolic cusp metric. Then it can be uniquely realized as the boundary metric of an ideal Fuchsian polyhedron. In the present paper we give a new variational proof of this result. We also give an alternative proof of the existence and uniqueness of a hyperbolic polyhedral metric with prescribed curvature in a...