Ramsey

Hi. I recently got into the PhD program in a top university in US. Before application period, I mailed 3 professors and none of them got back to me. Now I am admitted to the program and I do not know which of the professors should I contact again. Does anyone have any ideas? I think one of them might have been interested in my application that they have admitted me, and if I mail the wrong person, there will be a total mess.