Class A (type D) CpG ODNs (CpG-A ODNs) contain a central palindromic phosphodiester (PO) CpG sequence and a PS-modified 3â poly-G tail. The poly G tails form intermolecular tetrads that result in high molecular weight ordered structures.
Why does a tornado form when cold and hot air meet? The collision of warm and cold air is not the direct cause of a tornado, nor is it absolutely necessary. When a cold air mass pushes into a warm air mass (this is called a câ¦old front) the warmer, less dense air is forced upwards.
The tornado threat tends to be highest in March in a corridor from the Southern Plains into the Tennessee Valley and Deep South. Central Florida can also be a tornado hot spot in March. According to NOAA's Storm Prediction Center, Texas (11) and Florida (6) lead the way in March tornadoes from 1989-2013.