Who is the owner of this information?

The owner of the website is Yrjö Engeström. Several clues come together to confirm this. First, the Current Activities, Short Biography, etc. are written in first person ("I am interested"). Second, this is a university site: the University of Helsinki. Oftentimes, but not always, a tilde ( ~ ) denotes a personal folder. If a tilde is not used, pay attention to context clues. If you do some checking around on the page, you'll find other files that are in this professor's folder (/people/engestro/).