Methods for resolving invoice obligations are disclosed that include: a) providing at least one sales invoice, wherein each sales invoice comprises a credit value, b) providing at least one purchase invoice, wherein each purchase invoice comprises a debit value, and c) offsetting at least part of the debit value of a purchase invoice with at least part of the credit value of a sales invoice. The retracting mechanisms may be ganged together to form a multiple cord retraction mechanism. The stream is then cryogenically compressed in a first compressor to form a first pressurized gas stream. Each plane is separated by the partition wall. The preferred embodiment further includes a bi-directional serial data connection for transmitting data for transmission connected between the Mobile Station Modem and the Bluetooth radio frequency unit and a synchronous detector and transmit enabling serial data connection for receiving an enabling indication valid data at said radio frequency unit from the Mobile Station Modem. Covalent attachment of certain analogues of N-acyl L-homoserine lactones onto a medical device may provide the advantage of slowing biofilm formation in a manner that is targeted to the surface of the medical device and not the patient.