JOINT FILING AGREEMENT

                                                                       EXHIBIT 1

                             JOINT FILING AGREEMENT

     The undersigned hereby agree to the joint filing of the Schedule 13G to
which this Agreement is attached.

Dated: February 26, 2004

                                           OBERWEIS ASSET MANAGEMENT, INC.


                                           By:  /s/ Xxxxxxx X. Xxxxx
                                                --------------------------------
                                                    Xxxxxxx X. Xxxxx
                                                    Executive Vice President

                                                 XXXXX X. XXXXXXXX


                                                 /s/ Xxxxx X. Xxxxxxxx
                                                 -------------------------------


                                                 XXXXX X. XXXXXXXX


                                                 /s/ Xxxxx X. Xxxxxxxx
                                                 -------------------------------

                               Page 10 of 10 pages