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.
That means it is warmer and we have summer. The declination of the Sun on the vernal equinox is 0Â° 00'. On the day of the vernal equinox, day and night are nearly the same amounts of time. In the United States, there are about 12 hours of daylight on this day. March is the traditional start of tornado season in the United States.