Diversity in personalized news recommender systems is often defined as dissimilarity, and operationalized based on topic diversity (e.g., corona versus farmers strike). Diversity in news media, however, is understood as multiperspectivity (e.g., different opinions on corona measures), and arguably a key responsibility of the press in a democratic society. While viewpoint diversity is often considered synonymous with source diversity in communication science domain, in this paper,we take a computational view.We operationalize the notion of framing, adopted from communication science. We apply this notion to a re-ranking of topic-relevant recommended lists, to form the basis of a novel viewpoint diversification method. Our offline evaluation indicates that the proposed method is capable of enhancing the viewpoint diversity of recommendation lists according to a diversity metric from literature. In an online study, on the Blendle platform, a Dutch news aggregator, with more than 2000 users, we found that users are willing to consume viewpoint diverse news recommendations.We also found that presentation characteristics significantly influence the reading behaviour of diverse recommendations. These results suggest that future research on presentation aspects of recommendations can be just as important as novel viewpoint diversification methods to truly achieve multiperspectivity in online news environments.

We have developed explicit expressions and the corresponding computer code for all homogeneous space Green’s functions for coupled electromagnetic fields and poroelastic waves. The Green’s functions are derived from the basic equations in closed form in the wavenumber- and space-frequency domains. They are given for point sources of any type. This adds several Green’s functions to what has been published before. These Green’s functions can be used in integral equation formulations, for numerical model validation, and for studying earthquake-related electrokinetic effects. The wavenumber domain code for all Green’s functions is given with the numerical test on the basic equations to demonstrate correctness. The numerical codes to compute them in the space-frequency domain are also given. A numerical inverse fast Fourier transformation routine is used to provide space-time domain results. At seismic frequencies, the fast P-wave is radiated with the largest amplitude in all fields, except for the magnetic fields where no P-waves are generated. At ultrasonic frequencies and in the particle and filtration velocity fields generated by an electric current source, the slow P-wave has the strongest amplitude. In the filtration velocity and particle velocity, the slow P-wave is, respectively, three orders and one order of magnitude stronger than the fast P-wave.