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.
Cold fronts are represented by blue triangles on a weather map, and stationary fronts are represented by interchanging the symbols for warm and cold fronts on weather maps. Warm Front. A warm front is the surface boundary between a warm air mass and a cold air mass it is overtaking. The warm air moves into an area of colder, drier air. The air masses do not readily mix; therefore the warm air rises slowly over the colder air because it is less dense.