## 4 Methodology
ISO-alpha3 country codes are used ([[https://unstats.un.org/unsd/methodology/m49/](https://unstats.un.org/unsd/methodology/m49/)]([https://unstats.un.org/unsd/methodology/m49/](https://unstats.un.org/unsd/methodology/m49/)), accessed on 8 January 2022). In particular, in graph (a) the analyzed scholars are colored by country, in fact, by the country of their affiliation institution. Furthermore, grouping data by country, dots with the same color are not uniformly distributed. Considering the most represented countries, a significant anti-correlation can be observed, similarly to the general case. Considering, for example, the most represented countries, the following important values of anti-correlation can be observed: United States, \(-0.6826\); UK, \(-0.72154\); China, \(-0.51519\). Graph (b) also shows the average values of the Radius of Gyration and the H-index, grouping scholars by country. While the values are distributed over a smaller region than Figure 5, the graph shows that slight differences also exist among countries and, also, in this case, average values are scattered approximately along a line with a negative slope. These differences may signal the influence of geographical and cultural factors, but also of different organizational structures, national policies and research programs. For example, the Netherlands has many universities ranked among the best in the world, and thus the high impact its top research results do not come as a surprise. However, researchers in Dutch universities are also those with the lowest mobility (RoG). This may be influenced by a formal definition of strategic themes and research themes in each university, corresponding to precise groups of researchers. This kind of rigid structure often drives the assignment of local funds and benefits. One of the goals of recent reforms (2016-2017) is to create larger domains in which interdisciplinary research would be more

Figure 5: Scatter plot of single scholars (**a**) and their average values when grouped by research subject (**b**). Radius of Gyration is on the \(x\)-axis. H-index is on the \(y\)-axis. Labels are associated with the corresponding number of instances. easily accommodated ([[https://www.dejongeakademie.nl/shared/resources/documents/Abeginnersguide.pdf](https://www.dejongeakademie.nl/shared/resources/documents/Abeginnersguide.pdf)]([https://www.dejongeakademie.nl/shared/resources/documents/Abeginnersguide.pdf](https://www.dejongeakademie.nl/shared/resources/documents/Abeginnersguide.pdf)), accessed on 8 January 2022). Switzerland is instead at the opposite side of the spectrum of mobility (RoG). The Swiss research and higher education system is characterized by a strong focus on interdisciplinary, which facilitates mobility across research topics ([[https://www.usi.ch/sites/default/files/storage/attachments/press-higher-education-and-research-switzerland-sefri.pdf](https://www.usi.ch/sites/default/files/storage/attachments/press-higher-education-and-research-switzerland-sefri.pdf)]([https://www.usi.ch/sites/default/files/storage/attachments/press-higher-education-and-research-switzerland-sefri.pdf](https://www.usi.ch/sites/default/files/storage/attachments/press-higher-education-and-research-switzerland-sefri.pdf)), accessed on 8 January 2022). The same kind of interdisciplinary research context, favorable for mobility across research topics, characterizes large research venues, such as CERN. ### Scholars' Mobility Pattern

Modeling the authors' research activities as travel in a semantic space enables investigating another kind of result, related to the emergent patterns in the authors' trips in this space over the time. In particular, we looked for a mobility pattern considering the displacements between visited locations in consecutive years (_flight length_) by each author. Understanding these patterns may be of interest for different stakeholders because it is possible to estimate the probability that a change of a topic occurs among the top scholars analyzed.