(portion of unused NOL generated while taxpayer taxed as U.S. resident that would have been allocated and apportioned to gross income of taxpayer's wholly-owned LLC business activity had taxpayer been taxed on the income as a nonresident alien may be used to offset gross income that is effectively connected to LLC's business activity in the U.S.; taxpayer can carry over an unused NOL from the business activity to apply against business gross income after reacquiring U.S. residency; any remaining amount can offset taxpayer's gross income).