NovaStar Financial has taken aim at payment shock on adjustable-rate mortgages through the establishment of a dedicated unit that will monitor borrowers at risk for problems.The so-called “special solutions” unit is an outgrowth of an effort that began last year, when Nova-Star began studying its ARM portfolio to see if it could find ways to mitigate reset risks. As part of that effort, the REIT began making calls in advance to borrowers with…