How referrals work. A referral from your primary care physician can cover a period from 90 days to one year. Referrals for oncology, rheumatology and renal management are issued for one year. Your primary care physician will let you know when your referral is approved, or Blue Care Network will send you a letter in the mail.
Infinite impulse response (IIR) filters. IIR filters are the most efficient type of filter to implement in DSP (digital signal processing). They are usually provided as biquad filters. For example, in the parametric EQ block of a miniDSP plugin, each peak/notch or shelving filter is a single biquad.
The higher the MERV rating, the higher the effectiveness of the air filter Microparticle Performance Rating, or MPR for short, is a filter rating system developed by 3M to rate a filters ability to cature the smallest airborne particles. The higher the MPR rating the better the filters ability to capture particles from the air.