Best Times to Go to Florence, Italy. Avoid summers if you can, it's hot and packed with sweating tourists in July and August. That said, there's hardly a time you won't encounter tourists in Florence. If you must go in summer, make hotel reservations early.
Helical. Helical (adjective) is having a spiral form of many rounds. Helical can be a hairstyle curl, loop fold of a ribbon that serves as pony and a repeated dialogue of an actor that gives twist to the audience.
The A-DNA structure. A-DNA is one of the possible double helical structures which DNA can adopt. A-DNA is thought to be one of three biologically active double helical structures along with B-DNA and Z-DNA. It is a right-handed double helix fairly similar to the more common B-DNA form, but with a shorter, more compact helical structure whose base pairs are not perpendicular to the helix-axis as in B-DNA.