Not sure if this is a silly question, but I just noticed this:
public interface IActivityDao : IDao
{
IList GetAllSinceSe
Parameter names are required in an interface declaration for clarity of implementation and for reference. If someone were using your interface, the names of the method parameters are meant to be self documenting so the consumer of the interface understands what to pass to the method (eg when viewing the method description via IntelliSense)
And yes, when you implement the interface you can name the parameters whatever you want.