Mougc, Chris, and vijaysaxena:
Thank you all for your support and advice. Yes, I did put up statistics and I was lucky that my work actually can be applied in a broad spectrum of diseases (and that explains the good citation numbers from multiple disciplines). Apparently, the USCIS has no doubt that is "national interest," but as Chris pointed out, the key is to demonstrate you can stand out among people
in your field. Well, usually people use publications and citations to answer that questions, but it seems the combination of a picky adjudicator and my lackbuster number of publications nailed the coffin of my last petition. Of course, strong recos will help, but I remember that at least one of the 2005 AAO decisions dismissed an appeal by saying there was no "objective evidence" to support the claims/appraisals made by the reference letter writers. That's why I feel frustrated because I really emphasized the objective evidence (citations, apparently). I guess unless one's credential is very solid that the adjudicator cannot find any weakness to attack, we just have to accept the reality that there is always a chance that your case could end up with the hands of a tough adjudicatror. By the way, after reading the denial decision more carefully, I found that the adjudicator denying my case is beyond tough - he/she actually either misinterpreted my recos, or did not read them careful enough. Ex: in the RFE, he/she asked me to sumbit evidence showing I made "key contributions" in the two papers that I was not the first author, and I replied with the letter from the PI saying exactly that I did make key contributions to those projects I participated, and I highlighted that phrase in my reply to the RFE. In the denial letter, he/she dismissed that by saying, "....these general comments (i.e. my PI said I made key contributions) cannot overcome the presumption that a junior member (i.e. me) on a team including many senior scientists did not make key contributions."
All right, maybe I am missing something here, but I thought I directly answered his/her question already?
Thank you all for your kind support and advice again!