Under the Securities Exchange Act of 1934
(Amendment No. 4)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box x

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §13d-7 (b) for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

2

3

SCHEDULE 13D

4

(a)-(b)     Mr. Knott and Dorset: See Rows 7 through 11 and 13 on pages 2-3.  Of the aggregate number of securities reported by Dorset in each of Rows 7 through 11 on page 3 of this Schedule 13D, 6,222 are shares of common stock underlying directors’ stock options.  Of the securities reported as beneficially owned by Mr. Knott in each of Rows 7 through 11 on page 2 of this Schedule 13D,an additional 9,555 are shares of common stock underlying directors’ stock options. At each annual meeting of the shareholders of the Company since he joined the board of directors of the Company, Dr. Sabba received grants of restricted shares of Common Stock and/or stock options to purchase shares of Common Stock of the Company, each of which grants vests in twelve successive equal monthly installments from the date of grant or immediately upon a change in control or hostile takeover of the Company.  All such shares and options are included on pages 2 and 3, to the extent the grants have vested as of the date of this filing.  As a director of the Company, Mr. Knott also received such awards, which shares and options are included on page 2 only to the extent the grants have vested as of the date of this filing.

Mr. Knott individually has the sole power to vote 1,518,311 shares of Common Stock and dispose of 1,519,977 shares of Common Stock beneficially owned by Mr. Knott, the Partnerships, KPSRI and the Managed Accounts.  As President of Dorset, Mr. Knott shares with certain of Dorset’s clients the power to vote 1,666 shares of Common Stock beneficially owned, in the aggregate, by such clients, and is for the purposes of this Schedule 13D deemed to share with Dr. Sabba the power to dispose of the 16,222 shares of Common Stock beneficially owned by Dr. Sabba.  Mr. Knott does not have nor does he share with Dr. Sabba the power to vote any shares owned by Dr. Sabba.

None of the Partnerships, KPSRI or the Managed Accounts (except through Mr. Knott) either holds or shares with any person the power to vote or to dispose of the Company’s Common Stock.

(c)           No transactions in the class of securities reported on were effected during the past sixty days, except for those on the following days and at the following per share prices:

* The price reported for 8-19-11 in the table above is a weighted average price. The daily total of shares represented in that column was purchased in two transactions: (a) 12,800 shares at $11.9592 and (b) 15,000 shares at $11.9540.

(d)           The Partnerships, Knott Partners Offshore Master Fund, KPSRI and the Managed Accounts have the right to receive dividends and proceeds from the sale of the shares of Common Stock that may be deemed to be beneficially owned by the Reporting Parties. No individual person or entity has such right with regard to greater than five percent of the Common Stock.

5

(e)           As part of the Reverse Stock Split, the Company’s Certificate of Amendment of the Amended and Restated Certificate of Incorporation (the “Certificate of Amendment”) became effective.  The Certificate of Amendment, among other things, reduced the number of authorized shares of the Company’s common stock on a proportional basis from 200,000,000 shares to 33,333,333 shares.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

6