Excluding specific blogs

I'm using global posts feed to power the corresponding widget on my front page. I'm running it as an aggregator of sorts that allows visitors to see the latest headlines from the blog network.

The site is WPMU/BP.

There is one blog in particular that doesn't seem to add any value to the headlines list because the blog content is skeletal and generally uninteresting. It is not exactly spam, it is more nonsense. The issue is that the blogger is rather productive and so her posts are constantly present.

I want to remove her blog from the global posts feed, is there some way to exclude certain blogs from this? I still have the BP activity which will still display her content, and give her exposure, but I just need to remove her from the headlines list to improve the quality of the feed. Is there a way to do this?

You can see our usage of it here: http://teatra.de below the main image.