Document:

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                                                                   EXHIBIT 10.45

                                (NRG LETTERHEAD)

December 18, 2002

Mr. George P. Schaefer
11 High Mountain Drive
Boonton, NJ 07005

RE:   LETTER OF UNDERSTANDING REGARDING SEVERANCE BENEFITS

Dear George:

NRG Energy, Inc. (the "Company") is delighted with your acceptance of the
position of Vice President and Treasurer of the Company effective December 18,
2002 (the "Effective Date"). This letter reflects the Company's contractual
obligation to you regarding the severance benefits to which you would be
entitled in the event of your termination of employment under the circumstances
described herein. However, it is not a contract of employment. You will be
classified as an "employee at will" and your employment will be subject to
termination at any time, with or without cause.

o     In consideration of your acceptance of employment with the Company, your
      execution of this letter agreement and your performance of the obligations
      hereunder, the Company will provide you with severance pay under the
      following circumstances: (i) in the event that the Company involuntarily
      terminates your employment without Cause (as defined below) or (ii) you
      resign your employment with Good Reason (as defined below) after the
      Effective Date, you will receive severance pay in the amount of one times
      your annual base salary (as in effect on your termination date). The
      severance pay will be paid in the form of a single lump sum payment,
      commencing as soon as practicable after your termination date. In addition
      the Company will pay a lump sum for all costs associated with your health
      benefits under COBRA for a period of 12 months from the effective date of
      your separation. The employee will be responsible for making the COBRA
      payments to the applicable COBRA third party administrator.

o     For purposes of this agreement, the term "Cause" shall mean a termination
      of your employment which is the result of any of the following: (i) your
      felony conviction or your plea of "no contest" to a felony; (ii) any fraud
      by you in connection with the performance of your duties as an employee of
      the Company; (iii) any act of gross negligence or gross misconduct by you
      in the performance of your duties as an employee of the Company; (iv) your
      repeated and continued neglect of your duties as an employee of the
      Company (other than your neglect resulting from your incapacity due to a
      physical or mental illness); provided, however, that an event described in
      item (iv) above shall not constitute Cause unless it is communicated by
      the Company in writing thirty (30) days from the date the Chief Executive
      Officer knows of such event and is not corrected by you in a manner which
      is reasonably satisfactory to the Company within thirty (30) days of your
      receipt of such written notice from the Company.

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                                                                 George Schaefer
                                                               December 18, 2002
                                                                          Page 2

o     For purposes of this agreement, "Good Reason" shall mean your resignation
      of your employment as a result of a material and adverse change in the
      scope of your position that results in (i) duties and responsibilities
      that are not substantially equivalent to those of the position for which
      you were hired and (ii) a reporting relationship below executive senior
      management (i.e., below a CEO, CFO, COO); provided, however, that a change
      described above shall not constitute Good Reason unless it is communicated
      by you to the Company in writing thirty (30) days from the date you know
      of such event and is not corrected by Company in a manner which is
      reasonably satisfactory to you within thirty (30) days of the Company's
      receipt of such written notice from you.

o     In the event your employment ends at any time as a result of your
      resignation without Good Reason, the Company shall pay you the full amount
      of the accrued but unpaid Salary you have earned through the date of your
      termination, plus a cash payment (calculated on the basis of your rate of
      Salary then in effect) for all unused vacation time which you may have
      accrued as of the date of termination, and any unpaid reimbursement for
      relocation, business or living expenses to which you are entitled.

o     You will not be entitled to receive severance benefits if you die, retire
      or become disabled while employed by the Company.

o     Severance payment(s) hereunder shall be an obligation of, and paid by, the
      Company.

o     All of the Company's obligations under this Agreement and your Employment
      letter shall be binding upon the Company.

o     The severance benefits specified in this agreement are in lieu of any
      other severance benefit to which you may be entitled under any other plan
      or program of the Company including, without limitation, benefits
      otherwise available under the NRG Energy, Inc. Involuntary Severance Plan.

o     This agreement and all the terms hereof are confidential. You may not
      disclose, publicize, or discuss any of the terms or conditions hereof with
      anyone, except your spouse, attorney and/or accountant. In the event that
      you disclose this agreement or any of its terms or conditions to your
      spouse, attorney and/or accountant, it shall be your duty to advise said
      individual(s) of the confidential nature of this agreement and to direct
      them not to disclose, publicize, or discuss any of the terms or conditions
      of this agreement with any other person. Violation of this confidentiality
      provision shall result in immediate termination of this agreement, loss of
      all severance benefits and, to the extent determined by the Company in its
      sole and absolute discretion, termination of employment for Cause.

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                                                                 George Schaefer
                                                               December 18, 2002
                                                                          Page 3

George, if you are in agreement with the terms of this Letter of Understanding,
please indicate your acceptance thereof by signing the enclosed copy of this
letter and returning it to me.

Sincerely,

/s/ RICHARD C. KELLY

Richard C. Kelly
President & COO
NRG Energy, Inc.

ACCEPTED:

/s/ GEORGE SCHAEFER                                      2/21/03
--------------------------------------                  ----------
George Schaefer                                            Date<PAGE>
                                                                   EXHIBIT 10.11

                             AMENDMENT ONE TO LEASE

                  THIS AMENDMENT ONE TO LEASE ("Amendment") is made by and
between University Research Park, Inc., a Wisconsin non-stock corporation
(hereinafter referred to as "URP" or "Landlord"), as successor by merger to
University Research Park Facilities Corp. (hereinafter referred to as "URPFC"),
and Third Wave Technologies, Inc., a Wisconsin corporation (hereinafter referred
to as "Tenant").

A.       On September 1, 2001, URPFC entered into an Amended and Restated Lease
         Agreement (the "Lease Agreement") with Tenant for approximately 94,726
         square feet of space in a building located at 502 South Rosa Road,
         Wisconsin 53711 (the "Leased Premises").

B.       Effective December 31, 2001, URPFC and URP merged, with URP as the
         surviving corporation and successor to all of URPFC's rights and
         obligations, including as Landlord under the Lease Agreement.

C.       Landlord and Tenant wish to modify certain provisions of the Lease
         Agreement.

                  NOW, THEREFORE, in consideration of the foregoing, and other
good and valuable consideration, the receipt and sufficiency of which are
acknowledged by each party, the following amendments to the Lease Agreement are
hereby agreed to, effective September 1, 2002 (the "Effective Date").

                  1. Section 1.4 of the Lease Agreement is deleted in its
entirety.

                  2. Section 1.5 of the Lease Agreement is deleted in its
entirety and restated as follows:

                SECTION 1.5 SECURITY DEPOSIT. Tenant shall maintain with
        Landlord a security deposit in the form of a cash (or equivalent)
        deposit or acceptable letter of credit, in the amount of the lesser of
        $1,300,000 or the amount which is then payable as the Improvement
        Prepayment amount, as shown on Exhibit C, attached. This security shall
        secure all of the Tenant's obligations under this Lease Agreement or
        arising in the event of the Tenant's default.

                The cash deposit shall consist of one, or a combination of, (i)
        deposit accounts, certificates of deposit or banker's acceptances issued
        by an bank organized under the laws of the U.S. or any state thereof,
        with capital and undivided surplus of no less than $100,000,000.00 and a
        rating by Moody's of its unsecured debt securities of no less than A,
        provided that such obligations mature within 365 days from the date of
        acquisition thereof; (ii) Investments in United States treasury
        securities, provided that such securities mature within 365 days from
        the date of acquisition thereof; (iii) investments in commercial paper
        given the highest rating by a credit rating agency of recognized
        national standing and maturing not more than 270 days from the date of
        creation thereof; (iv) investments in mutual funds which are required to
        invest only in the foregoing. In each case the deposit shall be the
        subject of a pledge or security interest in favor of Landlord, and no
        other

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         security interests or encumbrances, in form and substance satisfactory
         to Landlord.

                The letter of credit shall be issued by a bank organized under
        the laws of the U.S. or any state thereof, with capital and undivided
        surplus of no less than $100,000,000.00 and a rating by Moody's of its
        unsecured debt securities of no less than A, shall have an initial term
        of no less than one year, and shall enable the Landlord to draw upon it
        to satisfy any obligations of the Tenant under this Lease Agreement or
        to establish a cash security deposit account if the Landlord is not
        furnished with a renewal of the letter of credit within fifteen (15)
        days before the expiration date of the letter of credit then held.

                  3. Section 2.1 of the Lease Agreement is deleted in its
entirety and restated as follows:

                  SECTION 2-1 BASE RENT, PREPAYMENT. Tenant shall pay to
         Landlord at its office in Madison, Wisconsin, or such other place as
         Landlord may designate in writing, and without any deduction or offset
         whatsoever, as base rent, the amounts on or in advance of the first day
         of each calendar month as shown on the rent schedule attached hereto as
         Exhibit C.

                  In the event that the interest rate on the Landlord's
         financing for the improvements covered by the Improvements rent, which
         is now 5.04% per annum, increases at its scheduled adjustment date, in
         March, 2005, the Landlord may give written notice to the Tenant,
         transmitting a revised Exhibit C, reflecting an increase in the
         Improvement rent. The increase in the amount of rent shall be equal to
         the increase in the amount of the Landlord's payments on its underlying
         financing for the improvements, using the same period of amortization
         as now applicable to the financing. Upon giving such notice the
         Improvement rent shall be deemed adjusted to the amount shown on the
         revised Exhibit C.

                  The Tenant may prepay all, but not less than all of the
         portion of base rent denominated on Exhibit C as the Improvement rent
         and the Deferred Base rent by paying the discounted amount shown on
         Exhibit C as the Improvement Prepayment Amount and the Deferred Base
         Prepayment Amount on or before September 1 of the year for which such
         prepayment amount is indicated. On and after the date of such
         prepayment no further Deferred Base or Improvement rent payments, as
         applicable, shall be required. The Improvement rent may not be
         so-prepaid unless the Deferred Base rent has previously been or is
         concurrently being repaid.

Exhibit C of the Lease Agreement is deleted in its entirety and restated as
Exhibit C in the form attached hereto.

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                  4. Section 4.3 of the Lease Agreement ii deleted in its
entirety and restated as follows:

                  SECTION 43 ASSIGNMENT OR SUBLETTING. Tenant agrees not to

         sell, assign, mortgage, pledge or in any manner transfer this Lease or
         any estate or interest there under and not to sublet the Leased
         Premises or any part or parts thereof without the prior written consent
         of Landlord in each instance which consent shall not be unreasonably
         withheld. Consent by Landlord to one assignment of this Lease or to one
         licensing or subletting of the Leased Premises shall not be a waiver of
         Landlord's rights hereunder as to subsequent assignment or subletting.
         Landlord's rights to assign this Lease are and shall remain
         unqualified. For any assignment or sublease of 20,000 square feet or
         more in a single or series of related transactions, (i) the Landlord
         shall not be required to consent in any event unless the Tenant shall
         concurrently pay the applicable Improvement Prepayment Amount and
         Deferred Base Prepayment Amount (or a comparably calculated amount for
         an assignment date that is in a month other than during a month for
         which a prepayment amount is shown), as shown on Exhibit C, attached,
         and (ii) the Landlord shall have the option to elect to enter into a
         new lease, directly with the proposed assignee or subtenant, on the
         same terms and conditions as the proposed sublease or assignment.

                  5. This Amendment shall not be effective until Tenant
establishes the security deposit provided for in section 1.5, as amended. If the
security deposit ii not established on or before December 30, 2002, this
amendment shall be void and of no effect.

                  6. Tenant shall promptly upon request reimburse Landlord for
all of its costs and expenses incurred in connection with this Amendment.

                  7. ALL OTHER TERMS AND CONDITIONS OF THE LEASE AGREEMENT, AS
AMENDED, SHALL

LANDLORD:                           UNIVERSITY RESEARCH PARK, INC.

                                    BY:      /s/ Mark D. Bugher
                                             -----------------------------------
                                             Mark D. Bugher, Assistant
                                             Secretary/Treasurer

                                    Date:    12/20/2002

TENANT:                             THIRD WAVE TECHNOLOGIES, INC.

                                    BY:      /s/ John Comerford
                                             -----------------------------------
                                             John Comerford, Vice President,
                                             General Counsel & Secretary

                                    Date:    12/23/2002

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