By some reports, the word samurai first appeared in the 12th century. For a long time, the samurai provided the main military force used against emishi and other clans. In the 1100s, two powerful clans served the emperor of Japan: the Taira clan, and the Minamoto clan. These two families became bitter rivals, and in 1192, Minamoto Yoritomo led his clan to victory over the Taira.
EEG measures brain activity and must demonstrate regular wave patterns to be considered valid. Therefore, by this rule the onset of life would be the time when fetal brain activity begins to exhibit regular wave patterns, which occurs fairly consistently around week 25. Previous to that time, the EEG only shows small bursts of activity without sustained firing of neurons.
The fetal period of prenatal development begins on the last day of the eighth week after fertilization and continues until birth. This stage is characterized by the exponential growth of the embryo, now called a fetus, and the development of fully differentiated organs and tissues.etween weeks 13 and 16, the baby begins to move with regularity. Lanugo, a fine, downy hair, begins to grow on the head. Meconium, a thick, dark green waste substance, is produced in the fetus' bowels and remains there (in most cases) until after birth.