Figure skating they may be distinguished. The two categories of jumps are toe jumps and edge jumps. The number of rotations performed in the air determines whether the jump is a single, double, triple, or quadruple (commonly known as a "quad"). The simplest jump begins with a waltz jump which can only be done in a half-leap and is not classified as a single, double, or triple jump. Senior-level male single skaters perform mostly triple and quadruple jumps in competition. Triple jumps other than the Axel are commonly performed by female single skaters. It is extremely rare for a female skater to
Double beta decay or double beta decay are predicted to be very long; hence, quadruple beta decay is unlikely to be realized. The eight candidate nuclei for quadruple beta decay include Zr, Xe, and Nd capable of quadruple beta-minus decay, and Xe, Ba, Gd, and Dy capable of quadruple beta-plus decay or electron capture. In theory, quadruple beta decay may be experimentally observable in three of these nuclei, with the most promising candidate being Nd. Double beta decay In nuclear physics, double beta decay is a type of radioactive decay in which two neutrons are simultaneously transformed into two protons, or vice versa,