Ten percent of the brain myth 20th century. For example, the functions of many brain regions (especially in the cerebral cortex) are complex enough that the effects of damage are subtle, leading early neurologists to wonder what these regions did. The brain was also discovered to consist mostly of glial cells, which seemed to have very minor functions. James W. Kalat, author of the textbook "Biological Psychology", points out that neuroscientists in the 1930s knew about the large number of "local" neurons in the brain. The misunderstanding of the function of local neurons may have led to the ten percent myth. The myth might have been
Electrically powered spacecraft propulsion for a prescribed duration) or unsteady (pulsed firings accumulating to a desired impulse). However, these classifications are not unique to electric propulsion systems and can be applied to all types of propulsion engines. Electrically-powered rocket engines provide lower thrust compared to chemical rockets by several orders of magnitude because of the limited electrical power possible to provide in a spacecraft. A chemical rocket imparts energy to the combustion products directly, whereas an electrical system requires several steps. However, the high velocity and lower reaction mass expended for the same thrust allows electric rockets to run for a long time. This