You need your PI and other professors to send the letter by themselves. I have a NAS member did it for me and he did over 30 schools (actually his secretary did it for him). I swear that majorities of my interviews are because his name. I did give a thank you gift to his secretary for her trouble.
it seems that left and right faces have been beaten, rabbit general (UTK ?) and levis (not MIT) both... so general hope to move on to social media science faculty just ago... http://www.mitbbs.com/article_t/Faculty/31555533.html
Well, I know English is my weakness that's why I have private grant editors. You be surprised how many PIs are in denial about their English abilities especially for native speakers.