EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, we, the signatories of the statement on Schedule 13D to which this joint filing agreement is attached, hereby agree that such statement is, and any amendments thereto filed by any of us will be, filed on behalf of each of us.

Dated: November 19, 2007
	Palo Alto Investors, LLC
	By:
	Name:	William L. Edwards
	Title:	President
	Palo Alto Investors, Inc.
	By:
	Name:	William L. Edwards
	Title:	President
	Palo Alto Small Cap Master Fund, L.P.
	By Palo Alto Investors, LLC, its general partner
	By Palo Alto Investors, Inc., its managing member
	By:
	Name:	William L. Edwards
	Title:	President
	Micro Cap Partners, L.P.
	By Palo Alto Investors, LLC, its general partner
	By Palo Alto Investors, Inc., its managing member
	By:
	Name:	William L. Edwards
	Title:	President
	UBTI Free, L.P.
	By Palo Alto Investors, LLC, its general partner
	By Palo Alto Investors, Inc., its managing member
	By:
	Name:	William L. Edwards
	Title:	President
	WILLIAM L. EDWARDS
	Name:	William L. Edwards