Orgasm men are capable of achieving them is supported by men who have reported having multiple, consecutive orgasms, particularly without ejaculation. Males who experience dry orgasms can often produce multiple orgasms, as the refractory period is reduced. An increased infusion of the hormone oxytocin during ejaculation is believed to be chiefly responsible for the refractory period, and the amount by which oxytocin is increased may affect the length of each refractory period. Another chemical which is considered to be responsible for the male refractory period is prolactin, which represses dopamine, which is responsible for sexual arousal. Because of this, there is
Refractory metals cubic except rhenium which is hexagonal close-packed. Most physical properties of the elements in this group vary significantly because they are members of different groups. Creep resistance is a key property of the refractory metals. In metals, the starting of creep correlates with the melting point of the material; the creep in aluminium alloys starts at 200 °C, while for refractory metals temperatures above 1500 °C are necessary. This resistance against deformation at high temperatures makes the refractory metals suitable against strong forces at high temperature, for example in jet engines, or tools used during forging. The refractory metals show