terms of being clear about what you need, four very nice people brought me chocolate muffins, so there's a lot to be said for being clear and i'm going to try and do it more frequently in my life in the future. also now we're going to talk about technical and engineering issues. what are specific tings people have tried and then we'll open it up more broadly. obviously all of these categories are somewhat artificial. we tried give them focus but they touch on each other in many many ways and in some ways that's richest part of the conversation. so we'll spend probably 20 minutes on the technical and engineering and go to this broader discussion. i'll start off by asking david to make some comments about