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 14, 2005

                                        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
                                            ------------------------------------

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