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.
Stationary fronts prolong bad weather. A cold front is the boundary between cool and warm air when the cool air is replacing the warm air. A warm front is the boundary when the warm air is winning the battle. When the pushing is a standoff, the boundary is known as a stationary front. Stationary fronts often bring several days of cloudy, wet weather that can last a week or more. Since neither the warm air nor the cold air are advancing, the stationary front weather map symbols combine both the cold front and the warm front symbols. Maps show stationary fronts with alternating triangles pointing away from the cold air and half circles pointing away from the warm air. Color maps alternate the cold front blue and warm front red. A weather map's frontal position shows where the boundary touches the Earth.