Can a search activity on the internet, or the entry of data into a database via an interface, be considered a User Task?
It depends, what the purpose of your modelling is. If your purpose were to model the design of an IT supported process for a workflow engine, you would probably want to answer the question "is this activity going to show up as a task in the inbox of a user/role participating in the workflow?" If yes, it would be a user task. If this role would perform some other IT-supported things at the same time before the workflow moves on to the next role, performing the research activity might be too granular. You would drive your users nuts, if they keep on completing tasks from their inbox leading to new tasks popping up immediately that concern the same topic. This would be like "micro management". In this case it would make more sense to have a single user task - maybe with a comprehensive user interface allowing the search for articles among other useful things in the same context.