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Università della Svizzera italiana

Network theory and switching behaviors : a user guide for analyzing electronic records databases

Gronchi, Giorgio ; Raglianti, Marco ; Giovannelli, Fabio

In: Future internet, 2021, vol. 13, no. 9, p. 12

As part of studies that employ health electronic records databases, this paper advocates the employment of graph theory for investigating drug-switching behaviors. Unlike the shared approach in this field (comparing groups that have switched with control groups), network theory can provide information about actual switching behavior patterns. After a brief and simple introduction to...

Università della Svizzera italiana

Block-enhanced precision matrix estimation for large-scale datasets

Eftekhari, Aryan ; Pasadakis, Dimosthenis ; Bollhöfer, Matthias ; Scheidegger, Simon ; Schenk, Olaf

In: Journal of computational science, 2021, vol. 53, p. 13

The ℓ1-regularized Gaussian maximum likelihood method is a common approach for sparse precision matrix estimation, but one that poses a computational challenge for high-dimensional datasets. We present a novel ℓ1- regularized maximum likelihood method for performant large-scale sparse precision matrix estimation utilizing the block structures in the underlying computations. We identify the...

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...

Università della Svizzera italiana

Multigrid methods for fractional diffusion equations

Trotti, Ken ; Krause, Rolf (Dir.) ; Donatelli, Marco (Codir.)

Thèse de doctorat : Università della Svizzera italiana, 2021 ; 2021INFO013.

Recent years have seen the rapid growth in interest towards fractional calculus. Fractional calculus plays an important role in modelling anomalous diffusion phenomena, however closed-form analytical solutions of such equations are rarely available, hence numerical estimates are needed. In this thesis we consider various fractional diffusion equations (FDEs), where different fractional ...

Consortium of Swiss Academic Libraries

The computational structure of environmental life cycle costing

Moreau, Vincent ; Weidema, Bo

In: The International Journal of Life Cycle Assessment, 2015, vol. 20, no. 10, p. 1359-1363

Consortium of Swiss Academic Libraries

Dictionary Learning for Fast Classification Based on Soft-thresholding

Fawzi, Alhussein ; Davies, Mike ; Frossard, Pascal

In: International Journal of Computer Vision, 2015, vol. 114, no. 2-3, p. 306-321

Consortium of Swiss Academic Libraries

Fast Update of Conditional Simulation Ensembles

Chevalier, Clément ; Emery, Xavier ; Ginsbourger, David

In: Mathematical Geosciences, 2015, vol. 47, no. 7, p. 771-789

Consortium of Swiss Academic Libraries

FACTS: Fully Automatic CT Segmentation of a Hip Joint

Chu, Chengwen ; Chen, Cheng ; Liu, Li ; Zheng, Guoyan

In: Annals of Biomedical Engineering, 2015, vol. 43, no. 5, p. 1247-1259