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                 Schedule
                  13D 
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                 CUSIP
                  No. 918284100 
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                 Page 2 of 6
                  Pages 
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                 1. 
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                 Names
                  of Reporting Persons. 
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| Calvin S. Koonce | ||||
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                 I.R.S.
                  Identification Nos. of above persons (entities only). 
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                 2. 
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                 Check
                  the Appropriate Box if a Member of a Group (See
                  Instructions) 
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                 (a) 
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                 £ 
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                 (b) 
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                 £ 
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                 3. 
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                 SEC
                  Use Only 
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                 4. 
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                 Source
                  of Funds (See Instructions) 
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                 PF 
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                 5. 
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                 Check
                  if Disclosure of Legal Proceedings Is Required Pursuant to Items
                  2(d) or
                  2(e) 
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              £ | ||
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                 6. 
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                 Citizenship
                  or Place of Organization 
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                 United
                  States  
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                 Number
                  of 
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                 7. 
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                 Sole
                  Voting Power: 833,909 
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                 Shares 
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                 Beneficially 
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                 8. 
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                 Shared
                  Voting Power: 0 
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                 Owned
                  by 
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                 Each 
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                 9. 
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                 Sole
                  Dispositive Power: 833,909 
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                 Reporting 
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                 Person With 
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                 10. 
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                 Shared
                  Dispositive Power: 0 
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                 11. 
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                 Aggregate
                  Amount Beneficially Owned by Each Reporting Person 
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                 833,909 
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                 12. 
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                 Check
                  if the Aggregate Amount in Row (11) Excludes Certain
                  Shares  (See Instructions) £ 
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                 13. 
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                 Percent
                  of Class Represented by Amount in Row (11) 
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                 16.5% 
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                 14. 
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                 Type
                  of Reporting Person (See Instructions) 
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                  IN 
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                 SCHEDULE
                  13D 
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                 CUSIP
                  No. 918284100 
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                 Page
                  3 of 6 Pages 
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                 Item
                  1. 
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                 Security
                  and Issuer 
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                 Item
                  2. 
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                 Identity
                  and Background 
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                 Item
                  3. 
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                 Source
                  and Amount of Funds or Other
                  Consideration 
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                 Item
                  4. 
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                 Purpose
                  of Transaction 
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                 SCHEDULE
                  13D 
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                 CUSIP
                  No. 918284100 
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                 Page 4 of
                  6 Pages 
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                 Item
                  5. 
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                 Interest
                  in Securities of the
                  Issuer 
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                 (c) 
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                 Set
                  forth on Schedule A is a list of all the transactions in the Issuer's
                  Common Stock since the most recent filing on Schedule 13D by the
                  Reporting
                  Person.  All such transactions were made in the open market
                  except as set forth on such
                  schedule. 
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                 (d) 
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                 No
                  Person other than the Reporting Person is known to have the right
                  to
                  receive or the power to direct the receipt of dividends from, or
                  the
                  proceeds from the sale of, such shares of Common Stock beneficially
                  owned
                  by the Reporting Persons. 
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                 (e) 
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                 Not
                  Applicable. 
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                 Item
                  6. 
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                 Contracts,
                  Arrangement, Understandings or Relationships with Respect to Securities
                  of
                  the Issuer 
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                 Item
                  7. 
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                 Materials
                  to be Filed as Exhibits 
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                 SCHEDULE
                  13D 
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                 CUSIP
                  No. 918284100 
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                 Page 5 of
                  6 Pages 
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                 Date: 
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                 December
                  11, 2007 
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                 /s/
                  Calvin S. Koonce  
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                 Calvin
                  S. Koonce  
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                 SCHEDULE
                  13D 
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                 CUSIP
                  No. 918284100 
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                 Page 6 of 6
                  Pages 
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                 Date
                  of Transaction 
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                 Number
                  of Shares of the Common Stock 
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                 Buy/Sell/Other
                  Transaction 
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                 Price
                  Per Share 
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                 11/29/2007 
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                 3000 
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                 Sell 
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                 51.626 
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                 11/29/2007 
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                 1656 
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                 Sell 
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                 51.8483 
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                 11/30/2007 
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                 2616 
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                 Sell 
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                 52.6867 
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                 12/03/2007 
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                 3691 
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                 Sell 
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                 51.8302 
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                 12/03/2007 
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                 3000 
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                 Sell 
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                 51.6952 
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                 12/04/2007 
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                 3809 
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                 Sell 
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                 52.1003 
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                 12/05/2007 
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                 5802 
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                 Sell 
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                 51.0645 
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                 12/06/2007 
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                 2352 
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                 Sell 
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                 50.5622 
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                 12/07/2007 
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                 2605 
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                 Sell 
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                 50.213 
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                 12/07/2007 
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                 2746 
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                 Sell 
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                 49.5547 
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                 12/10/2007 
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                 2395 
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                 Sell 
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                 51.1687 
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                 12/10/2007 
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                 12500 
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                 Sell 
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                 52.6608 
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                 12/11/2007 
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                 5081 
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                 Sell 
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                 53.3796 
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